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Freeze-thaw cycles and rainfall as triggering factors of mass movements in a warm Mediterranean region: The case of the Tramuntana Range (Majorca, Spain)
Abstract
Between 2008 and 2010, the island of Majorca (Spain) experienced the coldest and wettest winters of the last 40 years. Accumulated
rainfall was twice the average and values of intense rainfall up to 296 mm/24 h were recorded, very similar to those calculated
for a return period of 100 years. Additionally, high precipitation coincided with anomalous, low temperatures, with abundant
snowfall and freezing in the highest zones of the Tramuntana Range, in the northwest sector of the island. As a result, 34
mass movements were recorded on the range, which seriously affected the road network in an area of great importance for tourism,
as it welcomes 8.5 million visitors each year. Fourteen rockfalls, 1 rock avalanche, 15 landslides and 4 karstic collapses
were inventoried. The geological structure, formed by a series of NW overlapping thrusts, determines the distribution as well
as the failure pattern of the movements. Thus, the northern face of the range registered 68% of the mass movements: nine rockfalls
with planar failure took place as well as all the landslides recorded. Likewise, south-facing slopes have been affected by
longer runout rockfalls with a wedge-type failure. The thorough analysis of the meteorological data shows that most of the
movements have taken place after antecedent rainfall over 800 mm. Additionally, the rockfalls have also occurred after several
freeze–thaw cycles, being a determining and unusual factor in this warm region. Intense rainfall >90 mm/24 h also caused rockfalls
as well as exceptional very intense rainfall >120 mm/24 h caused landslides. The results aim to contribute to the design of
an early warning system coordinating emergency, infrastructure services and meteorological centres in a region of high risk.
... Additionally, water percolation within the rock joints can cause a loss of cohesion by removing clayey material and facilitating the dissolution of minerals. Several authors argue that rockfalls are more frequent when temperatures oscillate around 0 o C (Mateos et al. 2012;D'Amato et al. 2016;Matsuoka 2019;Hales and Roering 2007). ...
... In both study areas rockfalls are more common when at least four freezethaw cycles or three hot-cold cycles have been observed during the week before, regardless of the accumulated effective water inputs. This contrasts with the findings by Mateos et al. (2012) the rock mass, and the subsequent occurrence of rockfalls. However, defining thresholds for regional-scale early warning of rockfalls with the available data is still challenging. ...
This paper evaluates the relation between rockfall events and weather conditions for two regions in Norway – Romsdalen and Gudbrandsdalen and explores how rockfall frequency might change with future climate conditions. Our analysis focuses on understanding the relationship between rockfall occurrence and effective water inputs, including rainfall and snow melt, and temperature oscillations both in cold conditions (freeze-thaw cycles) and in warm conditions (hot-cold cycles). To accomplish this, regional weather data and rockfall information in the Norwegian Mass Movement Database have been employed. Our results indicate that temperature oscillations might be better suited than effective water input to depict the occurrence of rockfalls in the two study areas in Norway. Freeze-thaw cycles are most frequent during winter and spring, and hot-cold cycles are most frequent during summer. Climate change will affect rockfall seasonality and the frequency in which freeze-thaw cycles and hot-cold cycles are observed. Thus, altering the exposure of population and infrastructures to rockfalls.
... Many damaging rockfall events have been recently recorded in the Tramuntana region, such as the one in Banyalbufar, in 1993, or in Valldemossa, in 2005, that affected fishing huts and archeological sites, respectively [23,24]. During 2008 and 2010, an extraordinary cold and wet winter occurred on the island of Mallorca, resulting in daily rainfall values of up to 300 mm, annual accumulated rainfall that doubled the average [9] and freezing processes in the Tramuntana range [50]. These climatic conditions triggered 15 rockfalls with no fatalities but caused several damages to dwellings, power stations, and the road network. ...
... Analyzing this seasonality in tourism, in conjunction with the seasonality of rockfalls, has provided valuable insights into this natural phenomenon within the study region. It is well-documented that rockfalls in the Serra de Tramuntana are notably more frequent during the winter months [50], which coincide with the low tourist season. This observation is further affirmed by our updated inventory, which reveals that 52 % of rockfall events with known dates (Fig. 4B) occurred during the low season, in contrast to 27 % and 21 % during the middle and high seasons, respectively. ...
... For rock that contains natural fractures (e.g., veins, fissures, joints, flaws, and faults, etc.) in cold regions, the influence of repeated freeze-thaw (F-T) and disturbed stress on rock damage evolution is crucial to the long-time stability of rock structures (Mateos et al., 2012;Wang et al., 2020bWang et al., , 2020cWang et al., , 2020d. When rock mass experiences repeated F-T cycles, water-ice phase transformation occurs within the natural fractures, and rock volume will expand by 9% due to the generation of frost heaving force (Niu et al., 2019;Tan et al., 2011;Wang et al., 2020b;Zhou et al., 2019a). ...
... However, almost all those studies are focused on intact rock subjected to freezethaw treatment, and the freeze-thaw responses of the naturally fractured rocks are not well understood. Actually, it has been proved that fractures are more sensitive to freeze-thaw than rock matrix, water-ice phase transformation easily occurs within the natural fractures (Mateos et al., 2012;Tan et al., 2011). Huang et al. (2018) carried out laboratory tests on rock-like materials with a single crack under F-T and uniaxial compression conditions, and studied the crack growth characteristics and frost heaving cracking behavior. ...
The naturally fractured rock in the open pit slope is susceptible to irreversible damage caused by fatigue loads related to freeze-thaw weathering, blasting vibration, earthquakes and tramcar traffic. To ensure the safety of rock mass and reveal how natural fracture affects the damage modelling characteristics is of great concern. Hence, this work aims at investigating the fatigue damage evolution of rock from volumetric deformation caused by F-T and cyclic loads. The rock structural deterioration and damage accumulation were investigated as well as the stimulated natural fracture pattern. Results show the frost heaving force acted on natural fracture results in the rock volumetric changes. The damage variable expressed by volumetric strain presents a linear relationship with freeze-thaw cycles. In addition, the axial, lateral and volumetric strain of marble exposed to cyclic loads present a two-stage pattern, they first increase quickly and then get to steady and last for a long time. A new fatigue damage model was established by considering the freeze-thaw damage and mechanical damage simultaneously. The proposed coupling damage model can well describe rock damage accumulation. Moreover, the CT images further reveal the influence of the natural fracture on rock volumetric deformation and the final damage accumulation. It is suggested that the opening-mode natural fractures contribute a lot to rock freeze-thaw deformation and fatigue deformation.
... Hard rocks predominate, especially Jurassic limestone and dolostone, which constitute the framework of the mountains. These conditions determine frequent rockfalls, which have caused significant damage, specifically to the road network [18,30,126]. The Ma-10 road is a strategic road and constitutes the main transportation corridor on the northern face of the Tramuntana range. ...
... During the spanning period 2009-2017, the rockfall inventory collected by the Road Maintenance Service of Mallorca showed a total of 22 significant rockfalls in the area where the wildfire took place (Figure 12). Before the wildfire in 2013, 7 rockfalls were recorded in the burned section of the road between 2009 and 2013; 4 of them took place in 2010 when the island of Mallorca experienced the coldest and wettest winters of the last 40 years [126]. After the 2013 wildfire, between 2013 and 2017, a considerable increase in rockfalls was observed in the same section; a total of 15 rockfalls, which double the number of events for the pre-fire period (2009)(2010)(2011)(2012)(2013). ...
Understanding processes and conditions that lead to rockfalls during and after a wildfire in different geological contexts is crucial since this phenomenon is one of the major hazards in mountainous regions across Europe. Spain is one of the European countries with the highest rate of wildfires, and rockfalls cause high economic and social impact, with many fatalities every year. The increase of rockfalls during and after wildfires is connected with the merging of different factors, not only in the detached area but also in the propagation and potentially affected area. When wildfire occurred, many actions take place: changes in the mechanical conditions of the rocks, the loss of protective capacity from vegetation, the effect induced by firefighting activities and/or the impact by the high temperatures in the adopted protective measures. After the wildfire, there is an increase in frequency and intensity of rockfalls in the burned area, causing a major impact of rockfalls on not only road networks and built-up areas but also people living. Additionally, the removal of vegetation by wildfires causes an increase in the risk perception, related not only to detached blocks but also to the general appearance of the rock mass. In this review, the main factors that influence the occurrence of rockfalls after a wildfire are analyzed, and three actual case studies in Spain are presented to support the variety of conclusions obtained.
... These phenomena can progressively lead to the development of weak sectors within the rock mass that have the potential to evolve into failures. In fact, small-size failures usually originate from highly jointed rock masses that have been stressed by recurrent forcing, such as rainfalls and daily thermal cycles that can induce freezing and thawing events (Matsuoka and Sakai 1999;Gunzburger et al. 2005;Mateos et al. 2012;Collins and Stock 2016;Dietze et al. 2017;Matsuoka 2019). All of these factors are responsible for the accumulation of inelastic deformations within the rock mass, leading to permanent damage, i.e., the non-negligible reduction of mechanical strength. ...
... Similar outcomes were noted by Arosio et al. (2018), who analysed a three-year-long micro-seismic record collected on a limestone cliff. Regarding thermal forcing, the relevance of daily temperature variations and freeze-thaw cycles in the predisposition of rock falls has been widely documented (Mateos et al. 2012;Walbert et al. 2015;D'Amato et al. 2016). Additionally, the analysis of micro-seismic and acoustic emission datasets can help in monitoring ongoing damaging processes at a smaller scale (from metric to centimetric) (Xu et al. 2014a;Zhou et al. 2018;Colombero et al. 2018) since the inelastic strain associated with thermal oscillations is released as micro-seismic and acoustic emissions (Occhiena et al. 2012;Collins et al. 2014;Weber et al. 2018). ...
This study reports a comparative analysis of the environmental conditions and micro-seismicity recorded on a rock wall resulting from an intense meteorological event. The findings are focused on a quarry wall located in the Acuto Field Laboratory (Central Italy), where multi-parametric environmental monitoring is operating and an Artificial intelligence Camera Prototype has been placed to detect rock falls reaching a railway target. Six accelerometers were installed to detect micro-seismic events caused by the expected strong thermal transient caused by the Buran storm on February 2018. Within a few hours, a steep decrease in the average air and rock mass temperature down to 8 °C was recorded, and −4 °C and −8 °C were reached for the rock and air temperatures, respectively. A total of 103 micro-seismic events were analysed with respect to both rainfall and thermal forcing: while no correlation with rainfall was reported, the steep thermal transient was responsible for the strain effect that occurred during the heating phase of the rock mass following the Buran storm. An elastic deformation event with a maximum daily amplitude of 165 μ strain was recorded by the strain gages installed on the mm-joints due to the rock heating and cooling caused by the variation in temperature. The collected evidences show the relevance of short thermal transients in modifying stress conditions within rock masses and their relationship to a peculiar micro-seismic response. The main outcomes established the key role played by integrated monitoring systems to better understand the relationship between vibrational behaviour and environmental forcings in terms of understanding the precursors to rock failure.
... Observations in the field indicate that frost wedging is a significant contributor to rockfall in rocky cliffs located in cold regions ( Fig. 1) (Tharp 1987;Frayssines and Hantz 2006;Amitrano et al. 2012;Mateos et al. 2012;Lai et al. 2014;Liu and Wang 2024). Rock mass is a complex natural medium that contains different types of rock materials and various geological structures and defects, such as joints, cracks, and pores (Li 2013;Li et al. 2014Li et al. , 2015Li et al. , 2023Mu et al. 2017;Yang et al. 2022;Fan et al. 2024). ...
To explore the characteristics of cracking induced by frost wedging in hard rock, freezing tests of granite specimens that contained prefabricated slots filled with water were conducted in the laboratory. The freezing-driven crack initiation and propagation were numerically simulated by the extended finite element method (XFEM). The effects of tensile strength, slot depth, slot width and model size on the crack initiation and propagation were investigated in the numerical study. It was found that for a given freezing condition, a higher rock tensile strength and a larger model resulted in shorter crack lengths, while wider and deeper slots led to longer crack lengths. The crack growth rate increased with increasing in the slot depth and width, but decreased with increasing in rock tensile strength and model size. Furthermore, it was observed in the two-slot model that the crack growth was affected by the distance of the slot to the free side boundary of the model. Quantitative relationships between the crack growth length and the influencing factors were established for granite. The findings of this study provide insights into the mechanism of frost cracking in hard rock.
... Over time, the repetitive process of freezing and thawing leads to cyclic opening and closing of these fractures, which eventually decreases the rock strength and promotes the occurrence of landslides. Many researchers have studied the effect of freeze-thaw cycles as a landslide trigger on rock slopes (Krautblatter and Moser 2009;Mateos et al. 2012;Arosio et al. 2013;Guo et al. 2014;Macciotta et al. 2015;Macciotta et al. 2017a;Pratt et al. 2019). Yuan et al. (2021) investigated the degree of soil damage under freeze-thaw cycles and showed that the voids are expanded and further interconnected as the number of freeze-thaw cycles increases. ...
A 500 m long, 60 m high rock slope adjacent to Highway 837 in Alberta, Canada (C018 site) has a long history of landslides, with multiple occurrences of fallen material reaching and blocking the highway. Since 2000, 11 landslides have been reported. Previous studies have shown that a relationship exists between weather conditions and three distinct failure modes at this site: slides of frozen slabs of heavily weathered material, earthflows, and rock falls. Weather data have been analyzed for each recorded landslide, and the corresponding weather signature that led to each landslide has been investigated. Results show that antecedent precipitation, seasonal thawing, and short-term temperature fluctuations all play a significant role in landslide occurrences, and their effect can be quantified from a probabilistic approach. A clear weather signature has been identified for landslides occurring in the winter months. These landslides have occurred after episodes of precipitation that were followed by a decrease in temperature into freezing values with a duration of several days to weeks and subsequently followed by thawing with temperatures fluctuating around 0 °C. Moreover, statistical analyses on landslides occurring in spring and summer showed that if there is more than 20 mm of rainfall in a 14 day period, there is a 6% probability of a landslide, with a 0.1% probability of a landslide if there is less than 20 mm of rainfall in the preceding 14 days. This probabilistic approach provides a means to identify periods when landslide hazard is 60 times higher than the other time periods in spring and summer. Furthermore, the paper illustrates how this knowledge can be used to enhance our understanding of the potential effects of climate change on landslide risk and quantify the increase in landslide hazard based on climatic predictions.
... To assess the impact of MCs on river discharge, to identify floods and estimate their magnitude, we converted all daily discharge values into percentiles and categorized increases in daily discharges and classed them as moderate, severe, or extreme, using the 95th, 99th, and 99.9th percentiles as reference thresholds. We used these percentiles as they are commonly used for the analyses and characterization of floods in Mediterranean regions 87 . ...
Cyclones, whether tropical, extratropical, or of Mediterranean origin, play a crucial role in the Earth’s climate system, affecting environments and populations through strong winds, heavy rainfall, and flooding. While much research has focused on tropical and extratropical cyclones, Mediterranean cyclones have received less attention. These cyclones are generally weaker, smaller, and shorter-lived than their tropical or mid-latitude counterparts. However, recent events, such as Mediterranean cyclone Daniel in 2023, which caused severe flooding and thousands of deaths in Libya, underscore the major threat Mediterranean cyclones pose. In this study, we investigate the role of Mediterranean cyclones in triggering floods in Corsica, a region frequently affected by these storms. By analyzing cyclone tracks, streamflow data, and flood-related damage records from Corsica, we reveal a notable rise in river discharge linked to Mediterranean cyclones and show that they contributed to some of the most destructive floods recorded in Corsica between 1979 and 2020.
... Freeze-thaw cycles can lead to geological disasters in seasonally frozen regions, including landslides, rockfalls, and debris flows (Brideau et al. 2006;Sass and Krautblatter 2007;Mateos et al. 2012). It is of practical importance to assess the degree and evolution process of damage in rocks subjected to freeze-thaw cycles. ...
Freeze–thaw action is one of the primary factors causing rock damage in seasonally frozen regions. Investigating macroscopic and mesoscopic correlations is essential for examining the damage evolution of rocks subjected to freeze–thaw cycles. As a typical type of rock, sandstone was herein selected to examine the influence of freeze–thaw cycles on its mesoscopic structure and macroscopic mechanical properties. The computed tomography (CT) scanning images indicate that the structural integrity of sandstone is undermined disrupted at the mesoscopic level during freeze–thaw cycles, leading to changes in equivalent radius of the pores, of which the mesopores (i.e., pores with equivalent radii ranging from 100 to 500 μm) are most significantly affected. The results from uniaxial compression tests demonstrate that both the compressive strength and elastic modulus decrease exponentially with the number of freeze–thaw cycles. After 135 freeze–thaw cycles, the degradation rates of compressive strength and elastic modulus are 59.18% and 63.87%, respectively. Based on the macro-mesoscopic results, the macroscopic and mesoscopic damage variables were modified, whereby the freeze–thaw damage evolution functions were proposed. The damage evolution in sandstone subjected to freeze–thaw cycles is characterized by correlating the macroscopic mechanical response with the mesoscopic damage variable, thus deepening the knowledge of rock freeze–thaw damage mechanisms.
... In cold regions, fractured rock masses in highways, railways, tunnel slopes, and mining slopes of large openpit mines experience various disasters due to freeze-thaw cycles and cyclic loading [2][3][4][5]. Examples include freeze cracks in open tunnel sections [6], landslides [7], and rockfalls [8,9], significantly affecting the long-term stability of rock mass engineering in these areas. The primary mechanisms underlying rock freeze-thaw damage include ice volume expansion [10], hydraulic stress from unfrozen water in micropores [11], and internal stress induced by crystal growth [12]. ...
The failure of rock in cold regions due to repeated freeze–thaw (F-T) cycles and periodic load-induced fatigue damage presents a significant challenge. This study investigates the evolution of the multi-scale structure of fractured granite under combined freeze–thaw (F-T) cycles and periodic loading and develops a constitutive damage model. The results indicate that after F-T cycles, network cracks develop around pre-existing cracks, accompanied by block-like spalling. After applying the fatigue load, the nuclear magnetic resonance (NMR) T2 spectrum shifts to the right, significantly increasing the amplitude of the third peak. The freeze–thaw process induces a “liquid–solid” phase transition, weakening the original pore structure of the rocks and leading to meso-damage accumulation. The pores in fractured granite progressively enlarge and interconnect, reducing the rock’s load-bearing capacity and fatigue resistance. The combined effects of F-T cycles and periodic loading induce particle movement and alter fracture modes within the rock, subsequently affecting its macro-damage characteristics. The theoretical curves of the constitutive model align with the experimental data. The findings can serve as a theoretical reference for preventing and controlling engineering disasters in fractured rock masses in cold regions.
... It can be found that the UCS decreases with the increase of freezethawing numbers. For these results, Thaddeus et al (1979), Mateos and I-Azañón (2012), Niu et al (2016), Shervin et al (2021), Jing et al (2022) and Cao et al (2024a, b) concluded the vital role of water/ice phase transition during freezethawing: water/ice phase transition creates expansion force, destroying integrity of inner-structure and generate big pores/fissures in soils, which finally induces the decrease of UCS. Note that the specimens labelled as S1 have higher natural density (ρ n ) and smaller void ratio (e 0 ) comparing to that of S2. ...
In the previous decades, loess landslides with amount of 1992 occurred in Yili valley, Xinjiang autonomous region of China. These landslides have caused a series of engineering disasters. However, comprehensive report regarding the characteristics of these landslides has not been made, and the sliding mechanism is also not thoroughly clarified. In order to address these issues, extensive field surveys and laboratory tests have been conducted. These results conclude that the length/width, sliding thickness, altitude and the gradient of these loess landslides mostly locate in the range of 10–300 m, 0.5–20 m, 1000–2500 m and 10°–50° respectively. Additionally, these loess landslides in Yili belong to the snow-melt landslides, which primarily occurred in the snow-melt season from yearly mid-February to mid-May. For these snow-melt landslides, the sliding mechanism includes following parts: freeze-thawing action notably weakens the shear strength of superficial loess, resulting in the sliding of superficial loess layer. Moreover, freeze-thawing also promotes the inner-fissures growth in superficial loess, increasing its hydraulic conductivity and accelerating the infiltration of melted snow-water or rainfall into lower loess layer. As lower loess becomes saturated, its strength diminishes significantly, further inducing the deep sliding.
... In Mallorca, the island suffered persistent and high precipitation in the period spanning from 2008 to 2010 that caused a large number of slope failures [46]. Ref. [5] carried out a temporal analysis, by means of spectral techniques, using a set of monthly hydrological and meteorological series on the Serra de Tramuntana mountain of Mallorca, where they showed the predominant influence of ENSO, the NAO, and sunspots in the rainiest periods. ...
The island of Mallorca has experienced major interventions and transformations of the territory, with unprecedented urban development related to growing tourism activity. In this paper, we present a spatio-temporal analysis—by using spectral analysis techniques—of climate cycles on the island of Mallorca (Spain) and their correlation with the occurrences of landslides and flash floods. Both geohazards are closely related to wet periods, which are controlled by different, well-known natural cycles: ENSO, the NAO, sunspot, etc. Geostatistical methods are used to map the distribution of rainfall, as well as a spatial representation of the spectral confidence of the different natural cycles, to define the hazardous areas on the island. The cycles with the greatest influence on rainfall in Mallorca are El Niño–Southern Oscillation (ENSO) (5.6 y and 3.5 y), the North Atlantic Oscillation (NAO) (7.5 y), and Quasi-Biennial Oscillation (QBO). Recorded events of both rockfalls and flash floods exhibit a strong correlation with the climate indices of QBO, ENSO, the NAO, and sunspot activity. This correlation is particularly pronounced with QBO, as this cycle has a higher frequency than the others, and QBO is observed as part of the other cycles in the form of increases and decreases during periods of higher ENSO, NAO, and sunspot values. However, the impact of flash floods is also significant in the southeast part of the island, despite its lower levels of rainfall. The most dangerous episodes are related to ENSO (6.4 y) and the NAO. The validation of the methodology employed is strengthened by incorporating information from the flash flood data, as it offers comprehensive coverage of the entire island, compared to the landslide database, which is confined to the Serra de Tramuntana region. The study reveals that the city of Palma and the municipality of Calvià, as well as the central and eastern urban areas of the island, are the most vulnerable regions to intense rainfall and its consequences.
... Freeze-thaw cycles are important triggers for the mass movement [48]. According to Section 2.3, the temperature in the study area is highly variable throughout the year, with peaks at 37 • C and extreme lows at −28 • C. The intense freeze-thaw cycles experienced by the rock mass of the pit slope have resulted in continued structural deterioration and reduced stability of the rock mass. ...
Since the beginning of spring 2022, successive landslides have occurred in the eastern pit slope of the Wolong Coal Mine in Qipanjing Town, Otog Banner, Inner Mongolia, which has adversely affected the mine’s production safety. This study aims to reveal the deformation patterns and failure mechanisms of landslides. Firstly, this study establishes the stratigraphic structure of the eastern pit slope of the Wolong Coal Mine using extensive field geological surveys combined with unmanned aerial vehicle photography, drilling, and comprehensive physical exploration techniques. Indoor geotechnical tests and microscopic experiments reveal that rock mass typically exhibits the characteristics of expansibility and water sensitivity. Moreover, the mechanical parameters of the rock mass were determined using a combination of the window sampling method, the Geological Strength Index, and the Hoek–Brown strength criterion estimation theory. Finally, this study consolidates the previously mentioned insights and employs FLAC3D (7.0) software to assess the stress–strain characteristics of the excavated slope. The results indicate that the deformation mode of the Wolong open pit coal mine is the toppling failure of soft-hard-interbedded anti-inclined layered rock slopes. The unloading effect and rock expansion-induced softening lead to stress concentration at the slope corners and more substantial deformation, thereby accelerating upper slope deformation. The deformation and destabilization process of landslides is categorized into four stages: the initial deformation stage, the development stage of lateral shear misalignment, the development stage of horizontal tensile-shear damage, and the slip surface development to the preslip stage. This research offers valuable references and engineering insights for future scientific investigations and the prevention of similar slope-related geological hazards.
... Under the influence of frost wedging, the opening and length of micro-fissures and natural joints increase, 5,8,9 which is prone to rock overturning ( Fig. 1 in Li et al. 10 ), landslides, collapses rockfall ( Fig. 28 in Harris et al. 11 ) and other disasters. 10,[12][13][14] Additionally, the freeze-thaw cycle fosters the formation of flow channels for water in the ice wedges. 15 Water containing fissures propagate under frost wedging, easily forming a network of fissures and accelerating the loss of surface water and water in geological bodies. ...
The propagation of joints and fissures, included by the frost heaving pressure arising from the water-ice phase transition is considered as frost wedging. This process is widely observed and plays a crucial role in weathering of jointed hard rocks in cold regions. Despite some fundamental results achieved in former experimental studies, a unified theoretical model is still absent, hindering a thorough understanding of this process. To further explore the mechanism of frost wedging during the freezing process, this paper firstly carries out a frost heave test on a rock block bearing a single open fissure. The results indicate that the evolution of frost heaving pressure in the fissure can be divided into four stages: sealing of the open fissure by ice wedge, ice wedge slipping, crack propagation, as well as stabilization of the ice-filled fissure. Based on the laboratory test results, a unified model for the frost heaving pressure in a single open fissure is established, which comprehensively takes into account the mechanical interaction between ice, water and rock. The model is validated by the test result, and it can reasonably describe the formation of the sealing conditions and the process of crack propagation. Fracture of the ice-rock interface near the free surface increases the likelihood of ice wedge slip, while frost wedging mainly damages geological bodies during crack propagation.
... During the years 2008-2010, Mallorca experienced one of the coldest and wettest winters in living memory, with the highest rates of intense rainfall (up to 296 mm/24 h). The result was 34 mass movements triggered, along the Tramuntana Range [26]. Fortunately, there were no deaths but there were numerous cases of damage to dwellings, holiday apartment blocks, barns and power stations, and especially the road network in the Range (a), which caused significant economic losses in the different tourist resorts. ...
... These models have been modified to perform transient seepage-thermal-stability analysis by incorporating unsaturated hydraulic properties [55][56][57], soil thermal properties [58,59], and variable temperatures in the soil profile [60,61]. The improved models have been used for slope stability analysis by considering variable precipitation [62,63], mean annual temperature [59,64], mean climatic conditions for part of the year [61,65], intensity of periodic rainfall [66][67][68], and variation in air and soil temperature [69,70]. To the authors' knowledge, a comprehensive slope stability modeling comprising transient analysis under extreme climatic conditions has not been conducted. ...
Seasonal weather variations have a profound effect on the integrity of cohesionless soil slopes in the Canadian Prairies owing to the prevalent semi-arid continental climate. The primary contribution of this research is the development of a transient and two-dimensional stability model that is fully coupled with hydraulic and thermal flows. The model was used to predict the factor of safety (FS) for two slope geometries (18 m height and 26 m height) subjected to three weather scenarios (mean, extreme wet, and extreme dry) and four ponding combinations on the upstream and downstream sides of the slopes under no-load and train-load conditions. Results indicated that for mean climate conditions, FS trends fluctuate till April, followed by an increase that remains constant up to November and decreases thereafter. Generally, the FS shows subdued fluctuations and higher values for the high slope compared with the low slope. For wet climate conditions, the FS patterns are similar to mean conditions, albeit with reduced durations of stability during summer. For dry climate conditions, FS values are higher than mean conditions and nearly constant for most of the year. For no ponding and downstream ponding, FS > 1 throughout the year. In contrast, FS > 1 only during the summer (with reduced time in wet climate and extended time in dry climate conditions) for upstream ponding and upstream–downstream ponding. For train loading, FS shows subdued fluctuations and lower values than the corresponding no-loading scenarios for both slopes. The effects of climate conditions and ponding scenarios are further reduced for the high slope. These findings are useful for decision making with regard to the initial design and ongoing performance of natural slopes and embankments in the cohesionless soils of the region.
... Approximately two years after completing the field experiments, owing to F-T action, the bulk density and nutrient content of the vegetation concrete decreased substantially, and the vegetation coverage gradually decreased (Fig. 1b). This indicates that F-T cycling may be an important cause of engineering failures in seasonally frozen soil regions (Mateos et al., 2012;Liu et al., 2016;Fu et al., 2018). Therefore, the F-T resistance and sustainable fertility of vegetation concrete under F-T conditions must be further improved (Fig. 1c). ...
Vegetation concrete has been widely applied for the ecological restoration of bare steep slopes in short-term frozen and non-frozen soil regions in China. However, field experiments conducted in seasonally frozen soil regions have revealed decreases in the bulk density, nutrient content and vegetation coverage. This study aimed to clarify the evolution process and mechanism of the engineering properties of vegetation concrete under atmospheric freeze-thaw (F-T) test conditions. The physical, mechanical, and nutrient properties of vegetation concrete were investigated using six F-T cycles (0, 1, 2, 5, 10 and 20) and two initial soil water contents (18 and 22%). The results revealed decreases in the acoustic wave velocity and cohesive forces and an increase in the permeability coefficient of the vegetation concrete owing to F-T action. X-ray diffraction tests indicated that the decreased cohesive force was closely related to the overall decrease in the content of gelling hydration products in the vegetation concrete. Additionally, the contents of NH4+-N, PO43-P and K+ in the vegetation concrete increased, whereas that of NO3--N decreased. The loss rates of these soluble nutrients increased, indicating that the nutrient retention capacity of the vegetation concrete had decreased. Specifically, the decreased nutrient retention capacity was mainly related to the disintegration and fragmentation of larger aggregates due to F-T action. This study provides theoretical support for future research on improving the anti-freezing capability of ecological slope protection substrates in seasonally frozen soil regions.
... There are also inventories over a more specific spatial scale within a region or country that resulted mainly from the compilation of landslides after catastrophic triggering events (e.g. Hervás and Bobrowsky 2009;Mateos et al. 2012). In the case of Spain, there is a national database of landslides (the Spanish Land Movements Database, BD-MOVES, http:// info. ...
An updated and complete landslide inventory is the starting point for an appropriate hazard assessment. This paper presents an improvement for landslide mapping by integrating data from two well-consolidated techniques: Differential Synthetic Aperture Radar (DInSAR) and Landscape Analysis through the normalised channel steepness index ( k sn ). The southwestern sector of the Sierra Nevada mountain range (Southern Spain) was selected as the case study. We first propose the double normalised steepness ( k snn ) index, derived from the k sn index, to remove the active tectonics signal. The obtained k snn anomalies (or knickzones) along rivers and the unstable ground areas from the DInSAR analysis rapidly highlighted the slopes of interest. Thus, we provided a new inventory of 28 landslides that implies an increase in the area affected by landslides compared with the previous mapping: 33.5% in the present study vs. 14.5% in the Spanish Land Movements Database. The two main typologies of identified landslides are Deep-Seated Gravitational Slope Deformations (DGSDs) and rockslides, with the prevalence of large DGSDs in Sierra Nevada being first revealed in this work. We also demonstrate that the combination of DInSAR and Landscape Analysis could overcome the limitations of each method for landslide detection. They also supported us in dealing with difficulties in recognising this type of landslides due to their poorly defined boundaries, a homogeneous lithology and the imprint of glacial and periglacial processes. Finally, a preliminary hazard perspective of these landslides was outlined.
... Les chutes de blocs débutent généralement dans des zones (sub) verticales (Farvacque et al., 2020;Hantz et al., 2020;Varnes, 1978). La fracturation et la déstabilisation de la roche sont issues de phénomènes naturels tels que l'infiltration et les cycles de gel-dégel de l'eau (Coutard et Francou, 1989;D'Amato et al., 2016;Mateos et al., 2012). La mise en mouvement des blocs déstabilisés est induite par des phénomènes extérieurs, comme la pression interstitielle de l'eau, les racines des végétaux, les séismes, l'érosion glacière. ...
In mountain areas, the risk generated by natural hazards, rockfall in particular, is a significant threat to the population and for the socio-economic assets of these territories. In this context, while taking into account the topographical conditions as well as the volumes and velocities of blocks, forest can be used as an effective solution of protection against this hazard. As such, the maintenance and enhancement of the protective function of this nature-based solution (NBS) is an goal of forest management in these areas. For that purpose, it is mandatory to assess the capacity of trees to alter the trajectory of blocks, as well as their vulnerability to impacts by such projectiles.
In this research work, a numerical model (Discrete Element Method – DEM) dedicated to estimate the energy lost by blocks during the impact against a tree has been developed and successfully tested. This model also allows estimate the damage caused by the impact of a projectile and a tree. The specificity of this model lies in the use of a non-destructive in-situ vibration test (Pull – Release test : PR) for its calibration. The mechanical quantities used to describe the behaviour of the tree during an in situ PR test and during the simulation of an impact are : the stiffness of the trunk, the stiffness of the root system, the first vibration frequency of the tree, its dimensions and its mass distribution.
This model was used to carry out a numerical campaign of impact simulations (380,000 impacts in total) on trees of various dimensions and realistic mechanical behaviours. The results obtained were used to build a classification metamodel using machine learning algorithms, such as the support vector machine – SVM, to predict the vulnerability of the tree to the impact of a block.
The performance criteria of the DEM model were estimated using destructive test data from the literature and vibration tests (PR) carried out during this work on 6 spruce trees (Picea abies (L. Karst)). The amount of energy lost by the projectile during impact with a tree predicted by the model is in accordance with the literature. Two typical cases of impacts are identified: low-energy impacts with rebound of the projectile resulting in low tree damages, and high-energy impacts resulting in tree destruction.
This classification metamodel detects 92% of slightly damaged trees when all variables describing the tree and the impact are known, and 72% of them when the only variables known are the volume of the block and the data from the PR tests. The damage of a tree depends in particular on its diameter (∅𝐷𝑏𝐻), the stiffness of its root system, the speed and volume of the projectile, and the eccentricity of the impact point with the trunk axis.
The results of this work confirm that the dimensional and mechanical characteristics of the tree which can be quantified using non-destructive in-situ measurements (in particular by a PR type test), are sufficient to calibrate a tree model with realistic mechanical response to the impact of a block. Furthermore, it is found that these characteristics, together with the information about the impact and block, are necessary to predict the damage done to the tree after an impact.
Key words: Mountain forests, nature-based solution, natural hazard, rockfall, protective forests, non-destructive testing, Pull – Release modelling, numerical simulations, damage, vulnerability
... The freeze-thaw cycle is a very common phenomenon in seasonal frozen soil areas, which will significantly affect the mechanical properties of rock and soil, and expand the plastic deformation area of rock mass near the potential slip surface, thus reducing the stability of rock slope. Liu et al. (2006), Mateos et al. (2012) and Zhang et al. (2022b)made similar conclusions while investigating the freeze-thaw cycles and rainfall as triggering factors of mass movements, the influence of freeze-thaw cycles on mechanical properties of silty sand and characteristics, and causes of crest cracking on a high core-wall rockfill dam in different regions, respectively. Moreover, Momeni et al. (2016) have also shown an increase in freeze-thaw cycles, leading to a decrease in the uniaxial compressive strength, tensile strength, dry density, and longitudinal wave velocity of the rock mass. ...
The current highest glacial lake outburst floods (GLOFs) risk level is centered in the eastern Himalaya. GLOFs represent a serious threat to downstream inhabitants and ecological environment. In the context of climate warming on the Tibetan Plateau, such GLOFs will continue or even intensify in the future. Remote sensing and statistical methods are often used to diagnose glacial lakes with the highest outburst probability. These methods are efficient in large-scale glacial lake risk assessment but do not take into consideration the complexity of specific glacial lake dynamics and triggering factor uncertainty. Therefore, we explored a novel approach to integrate geophysics, remote sensing, and numerical simulation in glacial lake and GLOF disaster chain assessments. In particular, geophysical techniques are rarely applied to the exploration of glacial lakes. The Namulacuo Lake located in the southeastern Tibetan Plateau is considered as the experimental site. The current status of the lake, including landform construction and identifying potential triggering factors, was first investigated. Secondly, the outburst process and disaster chain effect were evaluated by numerical simulation based on the multi-phase modeling frame proposed by Pudasaini and Mergili (2019) implemented in the open source computational tool r.avaflow. The results allowed verifying that the Namulacuo Lake dam was a landslide dam with an obvious layered structure. Also, the piping-induced flood might have more severe consequences than the short-term ultra-high discharge flood caused by surge. The blocking event caused by a surge disappeared faster than that caused by piping. Therefore, this comprehensive diagnostic approach can assist GLOF researchers to increase their understanding of key challenges they are facing regarding GLOF mechanisms.
... Dilatation of rock mass and partial blocks, together with freeze-thaw cycles, is determined by temperature cycles (Weber et al. 2017 ). Rockfall events can also be triggered by severe rainfall (Maria et al. 2012 ) or high-velocity wind gusts (Sass 2005 ). These can be quantified using weather stations. ...
Rock mass characterization and rockfall/rock slope stability monitoring methods are one of the fastest evolving research areas in the field of geosciences. Traditionally, simple mapping, geodetical or geotechnical methods are used. The ongoing rapid development of monitoring methods is conditioned by engineering challenges when new infrastructure is nowadays being constructed in complicated geological conditions. These are represented by mountainous areas, deep gorges with steep slopes, or even active landslide sites. Traditional methods can be used within these monitoring demanding sites and bring high-quality monitoring results, sometimes with higher precision than modern state-of-art methods. This chapter reviews traditional rock slope stability monitoring methods and discusses their advantages, applicability, and strong/weak sides. Traditional methods are compared against newly introduced, modern state-of-art methods.
... The freeze-thaw cycle is a very common phenomenon in seasonal frozen soil areas, which will significantly affect the mechanical properties of rock and soil, and expand the plastic deformation area of rock mass near the potential slip surface, thus reducing the stability of rock slope. Liu et al. (2006), Mateos et al. (2012) and Zhang et al. (2022b)made similar conclusions while investigating the freeze-thaw cycles and rainfall as triggering factors of mass movements, the influence of freeze-thaw cycles on mechanical properties of silty sand and characteristics, and causes of crest cracking on a high core-wall rockfill dam in different regions, respectively. Moreover, Momeni et al. (2016) have also shown an increase in freeze-thaw cycles, leading to a decrease in the uniaxial compressive strength, tensile strength, dry density, and longitudinal wave velocity of the rock mass. ...
... During this period, the surface soil underwent a freeze-thaw cycle within one day, resulting in crisscross cracks on the slope. Freeze-thaw cracks provided an advantageous channel for the infiltration of rainfall and snowmelt (Mateos et al. 2012). ...
The Lashagou landslide group in Gansu Province, China, is a typical shallow loess landslide group caused by artificial slope cutting. In April 2018, local sliding of the landslide group damaged houses and blocked the G310 highway, leading to the relocation of the Lashagou village, which aroused widespread concern. Unfortunately, the spatiotemporal displacement characteristics and failure modes of the landslide remain unknown. In this study, a method for the estimation of two-dimensional deformation of landslides, based on the local parallel flow model, was presented. This method only needs two orbital synthetic aperture radar (SAR) images with different imaging geometries, and has high accuracy verified by global satellite navigation system (GNSS) observations. In practice, we first obtained the surface velocity and time series deformation of the ascending and descending orbits. The best-fit sliding direction and inclination of the landslide movement were then inverted by combining satellite imaging geometry and surface velocity. Furthermore, the two-dimensional deformation of the Lashagou landslide group in the sliding and normal directions was obtained. We found that the landslide was in the accelerated deformation stage during the wet season and the deformation was mainly concentrated in the northern part of the Lashagou village. The snowmelt and continuous rainfall were the main factors in the landslide deformation. In addition, the landslide surface displacement characteristics and deep stress states can be linked using a combination of two-dimensional deformation, combined deformation, and inclination, which provides evidence that landslide movement is controlled by one or more deep continuous structural planes. Our research shows that the two-dimensional deformation retrieval method can be applied to gravity-driven translational landslides to help prevent and mitigate landslide hazards.
... Rock failure is the main cause to many geological disasters, such as collapse, landsliding and tunnel collapse. Rock failures caused by temperature change and fatigue loading can lead to serious losses (Mateos et al., 2012;Strunden et al., 2015;Cui et al., 2022;Huang et al., 2018;Song et al., 2021). The freeze-thaw deterioration (Nicholson et al., 2000;Bayram, 2012;Freire-Lista et al., 2015;Ghobadi et al., 2015;Gao et al., 2020;Wang et al., 2021;Li et al., 2022) and fatigue (e.g. ...
Acoustic emission and thermal infrared signals are related to the process of rock breaking. In this paper, the acoustic emission and thermal infrared signals of rock are obtained during the loading process of indoor granite freeze-thaw cycle test and uni-axial compression test. Then the acoustic emission signals sent out during rock breaking are analyzed by short-time Fourier transform to get the peak frequency. infrared radiation thermographic sensor is applied to monitor and record the temperature change on the surface of rock so as to get the influence of thermal infrared radiation characteristics during rock materials deformation and breaking. Under the same axial stress, the samples passing through more freeze-thaw cycles have higher surface temperature. Both acoustic emission and thermal infrared temperature show that tensile failure is the main failure factor to granite samples. As freeze-thaw effect results in more micro fissures inside rock, the granite samples develop in the tendency of large breakage increases and small breakage decreases. This phenomenon shows that freeze-thaw cycle could restrict the heat release of granite sample.
... An example of this abnormal situation took place on Mallorca (Spain) in the period 2008-2010, when a combination of persistent precipitation and low temperature caused an unusual number of slope failures. This had a great impact on the regional economy, which revolves exclusively around tourism (Mateos et al., 2012). 18 MORLEs during the past 10 years were reported by 11 Geological Surveys (Mateos et al., 2020), with a total of approximately 150 fatalities and severe economic impacts. ...
Many fields of research relevant to climate-change-related policy are grounded in geological sciences-far more than is generally recognised by the public or policy makers. These fields include management of marine environments, urban development, groundwater , landslide risk, understanding the geochemistry of soils and water, and securing raw materials. Through the concerted collaborative efforts, over many years, of EuroGeoSurveys-the Geological Surveys of Europe-national datasets bearing on these and other areas have been harmonised at European scale and delivered through an online digital platform, the European Geological Data Infrastructure. This vast store of baseline data, information, and knowledge is crucial for informed pan-European decision making and is considered the core of a future Geological Service for Europe. De nombreux domaines de recherche per-tinents pour les politiques liées au change-ment climatique sont fondés sur les sciences géologiques-bien plus que ce qui est géné-ralement reconnu par le public ou les déci-deurs. Ces domaines incluent la gestion des milieux marins, l'aménagement urbain, les nappes phréatiques, les risques de glisse-ment de terrain, la compréhension de la géochimie des sols et de l'eau et la sécurisa-tion des matières premières. Depuis de nom-breuses années, grâce aux nombreux efforts de collaboration concertés des EuroGeoSur-veys-les services géologiques d'Europe-les ensembles de données nationaux portant sur ces domaines (ainsi que d'autres) ont été harmonisés à l'échelle européenne et fournis via une plateforme numérique en ligne-le European Geological Data Infrastructure. Cette vaste banque de données, d'informations et de connaissances est cruciale pour une prise de décision paneu-ropéenne éclairée et est considérée comme le coeur d'un futur service géologique pour l'Europe. Muchos campos de investigación concerni-entes con el cambio climático están relacio-nados con las ciencias geológicas-mucho más de lo que es reconocido por el público o por los responsables de políticas guber-namentales. Estos campos incluyen manejo de ambientes marinos, desarrollo urbano, aguas subterráneas, riesgos de deslizami-entos, la comprensión de la geoquímica de suelos y agua y el aseguramiento de mate-rias primas. A través de esfuerzos colabo-rativos mancomunados por muchos años de EuroGeoSurveys-Servicios Geológicos Europeos-se han integrado a escala euro-pea, bases de datos nacionales, relaciona-das con estos temas y otras áreas, para que estén disponibles en plataformas digitales en línea a través de la agencia Geológica de Datos de Infraestructura Europea. Este gran almacenamiento de datos es base de referencia, información y conocimiento, crucial para la toma de decisiones técni-cas a nivel pan-Europeo y se considera el núcleo central, clave para un futuro Servicio Geológico Europeo. scales, requiring decision-making that is resilient in the face of such rapid changes at local to Pan-European and even global scale.
... Rainfall Rainfall is a major factor for rockfalls in mountainous regions (Mateos et al. 2012). Annual average rainfall of Mogao Grottoes is 39 mm, but the average annual evaporation is 4348 mm, which is 111 times as high as the average annual precipitation (Liu et al. 2020a, b). ...
Hosting precious superb murals and painted sculptures from the fourth to the fourteenth century, the UNESCO word heritage site Mogao Grottoes are one of the most famous sites of Buddhist art. Although several reinforcement projects had been implemented, frequent rockfalls originated from the slope atop the cliff of Mogao Grottoes can be observed, representing a significant risk to both relics and tourists. Therefore, it is important to assess the rockfall hazard of the slope of Mogao Grottoes for the preventive protection as well as to inform future management decisions. In this study, rockfall hazard of the slope of Mogao Grottoes was assessed by using Analytic Hierarchy Process (AHP), Fuzzy-AHP (F-AHP) and AHP-TOPSIS methods and then the performances were evaluated by receiver operating characteristic curve (ROC) and area under curve (AUC). To execute these methods, a high-resolution digital surface model was first captured through UAV digital photogrammetry technology without contact. Belonging to four hazard levels (Very high, high, low and very low), the slope was divided into 10 units based on the slope topography. The hazard assessment result shows that 80% of the total slope units are at low rockfall hazard level and 20% slope units are at very high/high level, respectively. Moreover, loose debris and rainfall are confirmed as the most active causative factors. The result of AUC, ROC and recorded rockfall events reveal that the F-AHP is the most suitable method. Besides, this study also holds the potential applications of the F-AHP in the rockfall assessment for many other grottoes carved in conglomerate strata in Dunhuang.
... Yuan et al. (2021) investigated the degree of soil damage under freeze-thaw cycles and showed that the voids are expanded and further inter-connected as the number of freeze-thaw cycles increases. Many researchers have studied the effect of freeze-thaw cycles as a landslide trigger (Krautblatter and Moser 2009, Mateos et al. 2012, Macciotta et al. 2015, Macciotta et al. 2017a, Pratt et al. 2019. Fahey and Lefebure (1988) monitored the bedrock freeze-thaw at an actively eroding bedrock exposure on the Niagara Escarpment in southern Ontario. ...
Managing the risks associated with landslides requires adequately understanding the factors that affect their state of activity. Of these, weather is a known factor in landslides. Alberta Transportation (AT) is managing the geohazard associated with a 500 m long, 60 m high weak sedimentary rock slope adjacent to Highway 837 (Site C018) in central Alberta with a long history of landslides. Preliminary studies show that a relationship exists between weather and three distinct failure modes at this site: earthflows, rockfalls, and slides of frozen slabs of heavily weathered material. The climatic data at the site have been analyzed for each landslide, and the corresponding weather signature that led to each landslide has been investigated. Results allow for a probabilistic approach to quantify the weather-landslide relationship at this site. RÉSUMÉ La gestion des risques associés aux glissements de terrain nécessite une compréhension adéquate des facteurs qui affectent leur état d'activité. Parmi ceux-ci, la météo est un facteur connu dans les glissements de terrain. Alberta Transportation (AT) gère le géorisque associé à une faible pente rocheuse sédimentaire de 500 m de long et 60 m de haut adjacente à l'autoroute 837 (site C018) dans le centre de l'Alberta avec une longue histoire de glissements de terrain. Des études préliminaires montrent qu'il existe une relation entre les conditions météorologiques et trois modes de défaillance distincts sur ce site: les coulées de terre, les chutes de pierres et les glissements de dalles gelées de matériaux fortement altérés. Les données climatiques sur le site ont été analysées pour chaque glissement de terrain, et la signature météorologique correspondante qui a conduit à chaque glissement de terrain a été étudiée. Les résultats permettent une approche probabiliste pour quantifier la relation météo-glissement de terrain sur ce site.
... Freeze-thaw weathering is an important factor resulting in deterioration of rock structure and the associated stability of rock engineering in cold regions. Various rock mass instability events emerge in high-altitude and alpine regions (Mateos et al. 2012;Zhou et al. 2016;Kong et al. 2018;Forte et al. 2021), and the irreversible freeze-thaw damage of rock mass after repeated freeze-thaws have attract the attention of many scholars and engineers. Generally, a 9% volume expansion occurs when water freezes to ice, while ice exerts multidirectional tensile stress (i.e., frost heaving force) on rock and would lead to pore expansion and new micro-cracks. ...
Rock structural deterioration induced by coupled freeze–thaw and stress disturbance are a great concern for jointed rock mass during rock constructions in cold regions. Previous studies focused on fracture evolution of intact rock or flawed rock under freeze–thaw–static loads, but the coupling effect of freeze–thaw and cyclic loads on the pre-flawed hollow-cylinder rock is not well understood. This work investigated the influence of freeze–thaw on rock microstructure change and fatigue mechanical behaviors. Testing results show that rock strength, volumetric strain, and lifetime decrease with increasing F–T number. The stiffness degradation caused by cyclic loads is also impacted by the previous freeze–thaw damage. Additionally, the AE ring count and energy count decrease with the increase of F–T treatment. Large fracture signals are captured for rock that has smaller F–T cycles and at the stress-increasing moment. The AE b-value increases with F–T cycles, and it decreases rapidly near rock failure. Spectral analysis indicates that large-scaled cracking is prone to form for a sample having high F–T cycles. Moreover, 2D CT images reveal the differential crack network pattern at rock bridge segments and how it is affected by the previous freeze–thaw damage. The crack coalescence and hole collapse patterns and the associated structural deterioration of the rock bridge segment are obviously influenced by the F–T treatment.
... In many civil and mining engineering, repeated freeze-thaw (F-T) weathering results in the deterioration of rock structure and the geomechanical properties, and therefore severely impacts the stability of rock engineering. Plenty of geological hazards have emerged in the cold regions mainly caused by the F-T cycle, such as such as landslides, debris and rockfall etc. [1][2][3][4]. Under freeze thaw conditions, a 9% volumetric expansion occurs when water turns to ice [5][6][7][8], frost heaving pressure promotes the development of new micro-cracks and thus does great damage on rock engineering. ...
... As a last operation, we performed sensitivity analyses to investigate the role of water pressure and seismic actions as potential triggering factors for rockfall events [68]. As regards the first factor, different authors analyzed the water effect on rockfall/rockslide occurrence, evaluating both critical water heights within upslope tension cracks [69,70] and freeze-thaw episodes in cold areas, where ice which forms within cracks can lead to failure [71][72][73]. In this study, water pressure (u) variation was simulated through the "Percentage Filled Fissures" option in Swedge®, which allows to specify the average height of water within joint surfaces as a percentage of the completely water-filled state. ...
Archaeological areas in the mountain region of central Italy can be seriously threatened by geological hazards, and efforts are required to preserve cultural heritage. The Lucus Angitiae is a pre-Roman site located along the western edge of the Fucino Basin, the largest continental depression of central Apennines. The carbonate slope overhanging the area is affected by active rockfall processes from two main rock escarpments. In this paper, rockfall assessment was pursued through a 3D kinematic modelling, performed by adopting a probabilistic approach. Specific attention was dedicated to the choice and calibration of the input data, based on field evidence and a literature review. Two different sizes of wedge-shaped rock blocks were identified on rock escarpments, and specific stability analyses were performed. Sensitivity analyses accounting for possible triggering factors, such as water pressure increase and seismic action, were also carried out, together with an investigation of the seismological characteristics of the area. The results of the numerical simulations were used to design effective countermeasures in the framework of a mitigation plan for protection of the archaeological site. Finally, clues of gravity-driven slope deformations at the slope scale were documented, framing the rockfall process in a wider geological scenario.
... These conditions determine frequent rockfalls, which have caused significant damage during the past decades (Mateos et al., 2016). Special events took place during 2009, 2010 and 2013, when the island of Mallorca experienced very cold and wet winters (Mateos et al., 2012). These freezing, wet conditions triggered numerous rockfalls with severe damages, in special to dwellings and holiday apartment (Fig. 11). ...
Landslides have great socio-economic impacts in urban areas. The increasing consumption of land resources for urban purposes is leading to a large augmentation in people living in prone-locations to landslides. Spain is a clear example of this, where some dramatic, recent cases of landslides in new urban environments are analyzed. We show the methodologies and tools employed for characterizing and monitoring the landslide cases, using preferably remote sensing and numerical modeling. The survey of the three Spanish cases reveals that no adequate previous site investigation studies were carried out and the lack of effective building regulations were major drivers of landslide-damage.
... For example, the loess landslide in Gaoling District of Xi'an, Shaanxi in China is closely related to the seasonal freeze-thaw cycle, which is manifested by the destruction of pore structure and strength deterioration of the loess body under freeze-thaw conditions (Li et al., 2020). Additionally, the rockfalls have also occurred after several freeze-thaw cycles, being a determining factor in the Tramuntana Range, in the northwest sector of the island of Majorca (Spain) (Mateos et al., 2012). Therefore, it is a key scientific problem to evaluate the damage state of soil under long-term freeze-thaw cycles. ...
In permafrost regions, roads and soil slopes experience freeze–thaw cycles annually and the soil characteristics (such as strength and conductivity) change irreversibly. Several studies have been conducted on the evaluation of soil damage using soil mechanics principles and electrical measurements. Owing to the limitations of previous studies, such as low efficiency and the inapplicability of real-time testing for assessing damages, a real-time quantitative test method for assessing the damage degree of layered soil subjected to freeze–thaw cycles based on electrical measurements is proposed. An electrical measurement device was developed for testing the electrical parameters of multilayer soil. Combined with electrical measurements, freeze–thaw cycle tests were performed. The resistivity of each layer of soil under freeze–thaw cycles was determined. Additionally, microstructural parameters of the multilayered soil were determined through computed tomography to investigate the changes in the soil microstructure during freeze–thaw cycles. The porosity and pore distribution characteristics of the multilayered soil under freeze–thaw cycles were obtained using image processing methods, such as median filter and K-means clustering. As the number of freeze–thaw cycles increased, the soil porosity increased, and the pore structure became less complex. Based on the relationship between the soil resistivity and the microstructural parameters, the soil damage mechanism was described, and a damage factor was introduced in developing the model. Furthermore, the dynamic damage process of the multilayered soil under freeze–thaw cycles was evaluated using the damage model, and the settlement was used to verify the results. And the damage model can be applied to evaluate the damage state of soil in permafrost region
... In mountain and cold plateau areas, gravelly soil, a mixed soil consisting of fine soils and gravel particles, is widely distributed and susceptible to frequent F-T cycles due to high altitude and seasonal variations (Nyberg, 1993;Mateos et al., 2012;Qu et al., 2019). Besides, it also exists extensively in glacial tills, mudflows, landslides and colluvial soil deposits (Dong et al., 2017Luo et al., 2019). ...
Gravelly soils, characterized by a mixture of soil matrix and gravel aggregates, are widely distributed in high mountain and cold plateau areas. These soils are frequently subjected to freeze-thaw actions, and the hydraulic conductivity is crucial for analyzing hydrological processes and geological hazards. This study aims to investigate hydraulic conductivity in gravelly soils containing various contents of gravel particle fraction under cyclic freeze-thaw. The results show that the hydraulic conductivity in gravelly soils significantly depends on gravel content, confining stress, number of F-T cycles and initial water content. The presence of gravel particles modifies the porosity and pore connectivity/tortuosity in soil matrix, as well as affects the clay-gravel interfaces. With increasing gravel content, the overall gravel assembly transforms from a state of floating in the clay matrix to forming a contacted skeleton structure. Thus, the extensively developed loose clay-gravel interfaces due to F-T cycles result in a significant increase in hydraulic conductivity. Increasing confining pressure significantly reduces the clay matrix void ratio and thereby decreases the hydraulic conductivity, while no longer recovers the degradation in clay-gravel interfaces induced by F-T cycles. Different initial compacted water content provides different soil structures, divided by the optimum water content (wopt). A prominent increase of hydraulic conductivity after F-T cycles occurs in samples compacted at the dry side of wopt, while a slighter increase at its wet side.
... Under susceptible conditions, rockfalls occurrence can be determined by a variety of natural processes, acting both over short or long term. Seismic shaking/acceleration or rainfall-induced pore pressure increases can be easily recognised as short-term rockfall triggers, whereas it is more difficult to identify long-term triggers, for example, related to frost and thaw cycles or thermal rock movements and expansions (Luckman, 2013;Mateos et al., 2012). ...
Modelling rockfall phenomena is complex and requires various inputs, including an accurate location of the source areas. Source areas are controlled by geomorphological, geological, or other geoenvironmental factors and may largely influence the results of the modelling. In the Canary Islands, rockfalls are extremely common and pose a major threat to society, costing lives, disrupting infrastructure, and destroying livelihoods. In 2011, the volcanic event on the island of El Hierro triggered numerous rockfalls that affected strategic infrastructures, with a substantial impact on the local population. During the emergency, the efforts performed to map the source areas and to model the rockfalls in the considerably steep landscape characterising the island were not trivial. To better identify the rockfall source areas, we propose a probabilistic modelling framework that applies a combination of multiple statistical models using the source area locations mapped in the field as the dependent variable and a set of thematic data as independent variables. The models use as input morphometric parameters derived from the Digital Elevation Model and lithological data as an expression of the mechanical behaviour of the rocks. The analysis of different training and validation scenarios allowed us to test the model sensitivity to the input data, select the optimal model training configuration, and evaluate the model applicability outside the training areas. The final map obtained from the model for the entire island of El Hierro provides the probability of a given location being a potential source area and can be used as the input for rockfall runout simulation modelling.
... Our study also converges with findings from the Bavarian Alps (Krautblatter and Moser, 2009) where a 5-yr record of rock fragments found in traps shows that 90% of all small-magnitude rockfalls were triggered by rainstorms. At larger scale, a similar dependency of rockfall from precipitation has been reported for non-glaciated cliffs in Burgundy (France; Delonca et al., 2014), the Tatras (Poland; Zielonka and Wronska-Walach, 2019), the Canadian Cordillera (Macciotta et al., 2015), Hong-Kong (Chau et al., 2003), the Tramuntana Range (Spain; Mateos et al., 2012) or the Japanese Alps (Matsuoka, 2019;Imaizumi et al., 2020). In the latter case, based on a coupled geomorphic and microclimatic monitoring, Matsuoka (2019) explains the increasing rockfall frequency by raised water pressure in rock joints or the lubrification of joints after rainfall. ...
To overcome the lack of historical archives at active rockfall environments, dendrogeomorphic techniques have been used extensively on forested slopes since the early 2000s and several approaches developed to extract rockfall signals from tree-ring records. Given the unpredictable nature of rockfall, these reconstructions are, in principle, of great help when it comes to relate fluctuations in rockfall activity to meteorological variables. Yet, so far, dendrogeomorphic time series were only rarely compared with meteorological records. Here, we ascribe this shortfall to the absence of clear guidelines on how to optimize the sampling strategy. In order to test this hypothesis, we capitalize on the extensive dataset of rockfall impacts recorded in trees growing in a mixed forest plot within the French Alps. We designed six different scenarios retrospectively and compared rockfall reconstructions with meteorological records. Our results demonstrate that reconstructions that include trees located in the most active segments of the plot (i.e. close to the cliff and over periods lacking multidecadal trends in the reconstruction) capture summer precipitation as the main driver of rockfall activity more clearly. This result is in line with monitoring studies from calcareous cliffs in the Alps located outside periglacial environments thus confirming the robustness of our approach.
... The number of days to be considered depends on the characteristics of the terrain and climate, which may vary widely depending on the local settings (Aleotti, 2004;Crozier, 1999;Garcia-Urquía, 2016;Glade et al., 2000;Guzzetti et al., 2007;Li et al., 2011;Ma et al., 2016;Wieczorek, 1987). For shallow landslides in slopes covered by permeable colluvium, where the interstitial pressure dissipates rapidly, the antecedent rainfall should not be so important, since the rainfall itself generates the hydrological conditions required for instability (Mateos et al., 2012). Also, the antecedent soil moisture conditions can be important for medium and long duration landslide trigger rainfall events (Zêzere et al., 2015). ...
Deba area is intensely affected by frequent shallow landslides triggered by rainfall. This contribution explores the role of rainfall in landslide activity during a quite long time span (60 years), from a large network of rainfall gauges and a complete inventory of landslides. Out of 1,180 landslides inventoried, more than 50% occurred simultaneously in 6 known dates, corresponding to 6 episodes triggering multiple landslides; 3,241 rainfall episodes have been automatically recognized and characterized in terms of rainfall amount and duration, providing a representative dataset that covers a wide range of movement types and behaviors.The relationship between rainfall episodes driving multiple movements simultaneously has not been explored in depth so far in northern Spain. The extraordinary character of the triggering rainfall has been assessed and empirical rainfall thresholds (total amount, and mean intensity), producing multiple landslides, have been found and compared with others described in the literature. Also, the meteorological conditions associated to those extreme events have been recognized: multiple landslide occurrences are triggered by extreme convective rainfall: intense, short and with limited horizontal extent, as well as a marked summer-autumn seasonality. This weather pattern is more characteristic of Mediterranean areas than of mild marine west-coast climates.
... Rainfall intensity and frequency, snow thickness and snow melting rate can change the soil matric suction and affect the shear strength (Subramanian et al., 2018;Yan Long et al. 2019). The magnitude of temperature, its frequency and duration of periodic changes also have a significant impact on the soil physical and mechanical parameters (Qi et al., 2006;Rosa et al., 2012;Zhou et al., 2016). Field observations and https://doi.org/10.1016/j.coldregions.2020.103181 ...
The instability of irrigation reservoir bank slopes in cold regions has seriously affected the benign development of irrigation areas and agricultural production in recent years. To predict and evaluate the slope failure caused by freeze-thaw cycles, a two-dimensional numerical model of thermo-hydro-mechanical multi physical fields of a reservoir soil bank slope is established based on field investigations, laboratory tests and prototype observations. The relationship between the sliding surface temperature and the soil mechanical parameters is proposed by a secondary development program. The generation of the cracks on the bank slope top is explained from the viewpoint of temperature. The hydrothermal changing process of the bank slope under the external temperature is analyzed and compared with the measured data. The long-term degradation process of the soil bank slope under freeze-thaw cycles is studied, and the evolution law of its safety factors with the hydrothermal variation at the sliding surface is quantitatively revealed. The results show that the freeze-thaw cycles have an obvious accelerating effect on the soil bank slope instability, and the safety factor is decreased by 10.43% after 5 freeze-thaw cycles, which directly leads to the bank slope failure
... At broader scale, similar dependency of rockfall to precipitations have been reported for nonglaciated cli by e.g. Delonca et al. (2014) in Burgundy (France), Zielonka and Wro«ska-Waªach (2019) in the Tatras Mountains (Poland),Macciotta et al. (2015) in the Canadian Cordillera,Chau et al. (2003) in Hong-Kong,Mateos et al. (2012) in the Tramuntana Range (Spain) or byMatsuoka (2019) in the Japanese Alps. The later, based on coupled geomorphological an microclimatic monitoring, explain increasing rockfall frequency by raise water pressure in rock joints or lubrication of joints after rainfalls(Matsuoka, 2019). ...
Rockfalls are one of the most common geomorphological processes in the steeply sloping environments. Despite their limited volumes, rockfalls pose a significant hazard, due to their rapid evolution, high velocity and impact energy, but their unpredictable occurrence hinders detailed investigation of their dynamics and drivers under natural conditions. As the relative influence of rainfall, snowmelt, temperature, or freeze–thaw cycles have long been identified, based on medium-term monitoring methods, as the main drivers of rockfall activity, increasing rockfall hazards triggered by climate change are a major concern expressed both in scientific and non-scientific media.At high altitude sites, unequivocal relationships have been established between heightened rockfall activity, permafrost thawing and global warming. By contrast, below the permafrost limit, in the absence of longer-term assessments of rockfall triggers and possible changes thereof, our knowledge of rockfall dynamics remains still lacunary as a result of the persisting scarcity of exhaustive and precise rockfall databases.Over the last two decades, dendrogeomorphology – based on the analysis of damage inflicted to trees after rockfall impacts – has been used to overcome certain limitations inherent to historical archives and reconstructions of rockfall activity have been developed. Paradoxically, tree-ring reconstructions have only rarely been compared with climatic data to precisely constrain the potential meteorological triggers of process activity or to detect potential influences of global warming mostly due to the absence of clear recommendations to derive reconstructions that optimally capture the climatic signal in rockfall-prone environments.In this context, this PhD thesis first aims at proposing clear methodological guidelines to optimize sampling strategies of trees so as to precisely quantify uncertainties in dendrogeomorphic reconstructions back in time. Our results clearly evidence that the high-resolution mapping of stems on the studied combined with a careful selection of tree-species located at the vicinity of the cliffs improve the robustness of our reconstructions at the Saint-Guillaume (mixed forest stand, Vercors massif, French Alps) and Valdrôme (monospecific planted forest stands, Diois massif, French Alps) studied plots.In the second part, we capitalize on rockfall activity derived from optimized reconstructions and on the high-spatio-temporal resolution of the SAFRAN reanalyses, to precisely identify the meteorological triggers of rockfall events. At the interannual scale, our results evidence that summer precipitations and intense rainfall-events are the main drivers at both sites while no clear impact of temperature or freeze-thaw cycles could be detected.Finally, we compare decadal fluctuations existing in both tree-ring records with climatic series available for the period 1959-2017 with the purpose to detect the potential impacts of global warming on rockfall activity. In the Vercors massif, we explain increasing rockfall activity observed in the reconstruction since 1959 by a rapid forest recolonization and the overrepresentation of young sensitive trees rather than by climate change. In the Diois massif, the absence of significant trend suggests that a premature warning of increasing rockfall hazard, is not supported by the existing data. Yet, the weak robustness of the multiple regression models used here, the limited increase of temperature at the study sites and the incompleteness of our tree-ring reconstructions suggest that these results have to be treated with cautiously. All in all, this PhD thesis clearly demonstrates the added-value of the dendrogeomorphic approach to reconstruct rockfall activity, assess the meteorological driver of past events as well as to detect the potential impacts of environmental changes on the process dynamics.
Rock pores crack and expand subjected to freeze-thaw cycles, resulting in the reduction of their physical and mechanical properties, it is necessary to study its evolution and deterioration mechanism. However, the majority of existing studies employ a singular pore testing methodology, and neglecting the impact of the thawing process on frost heave damage in rocks. To address this, this study employs a combination of non-destructive testing techniques, including nuclear magnetic resonance (NMR) and computed tomography (CT) scanning, to comprehensively analyze the evolution of pores during freeze-thaw cycles. Investigating the migration and redistribution of pore water and its effect on frost heave damage in sandstone during the freeze-thaw process. Finally, the study examines the mechanisms of pores frost heave initiation and propagation in sandstone during freeze-thaw cycles. The results demonstrate that freeze-thaw cycles result in an expansion of pore volume at all scales within the samples. However, the degree of expansion varies, with macropores, mesopores, and micropores exhibiting a less pronounced increase in sequence. During the freeze-thaw process, water in sandstone pores redistributes, moving from larger to smaller pores. The saturation of water increases in micropores, but decreases in mesopores and macropores, thereby rendering micropores more susceptible to frost heave initiation in subsequent freeze-thaw cycles. With repeated freeze-thaw, the expansion of rock pores will continue in the direction of the lowest tensile strength, eventually forming macroscopic cracks. This study provides valuable insights into the mechanisms of freeze-thaw disaster genesis in rock masses.
Freeze-thaw cycles are recognized as one of the key triggers for some major landslides in cold regions around the world. Though the effects of freeze-thaw cycles on the rock strength degradation have been studied extensively, little effort has been made to qualitatively evaluate how it contributes to the evolution from a stable rock slope to a large-scale mass movement. In this study, we use a discrete element-based numerical model to simulate the entire process of the initiation of landslide under the action of freeze-thaw cycles in a slope with randomly distributed initial cracks. The main goal of this work is to quantitatively describe the landslide evolution process regarding the slope displacement, crack propagation, stress chain and load-bearing structure. Our results show the essence of the displacement evolution of a landslide subjected to freeze-thaw cycles; namely frost heave pressure induces the generation of new cracks, leading to the failure and reconstruction of the load-bearing structure of the slope. Deep-seated landslides can occur when the slope is crossed by a fault; otherwise, the slope is prone to surface erosion or shallow landslides.
The mesoscale effect of climate change and engineering activities on a superficial frozen soil–rock mixture (FSRM) in regions is complex. The decrease in strength caused by particle ice film ablation under temperature rise has various effects, such as upper subgrade settlement deformation. However, the internal mechanism of FSRM strength degradation remains unclear. Triaxial and nuclear magnetic resonance tests on FSRM were performed at various temperatures to clarify the mechanism of FSRM internal degradation. The results show that the strength, cohesion, and internal friction angle of FSRM decrease with increasing temperature, and the attenuation is significant in the range of −5 to 0°C. The change in ice–water content can be divided into three stages (i.e., freezing, phase transformation, and complete melting). In the three stages, the maximum free water is only 24%, while the maximum bound water is 100% above 0°C. Based on the microscopic test results, a mesoscopic calculation model for FSRM particles was developed. It was found that the work between particles is consistent with the law of strength degradation, and the friction function by particles gradually changes to bite work with increasing temperature. By introducing the strain energy theory, the strain energy generated by particle shear work is considered the key index to reflect FSRM strength. The particle ice film locking effect is weakened under temperature rise, and the increase in water weakens the strain energy generated by the work of the bite friction between particles during the shear process. At the macro level, the strength of FSRM deteriorates.
Within an international cooperation network (France, Spain and Portugal) involving researchers, first responders and civil protection authorities, a crisis exercise was held simultaneously in Mallorca and Ibiza (Balearic Islands, Spain). The objectives were to test crisis management procedures defined by operational actors, integrating new developed scientific tools related to landslides and rockfalls, as well as the internal relationship with the new created Technical Advisory Committee. The initiative included a training module for all stakeholders before the exercise explaining the scientific tools used for supporting the decision-making process during the exercise, as well as a field trip in the Tramuntana range in Mallorca to gain first-hand knowledge of the geological hazards threatening the region, mainly rockfalls. More than 70 people were involved in the training exercise, including researchers, civil protection, civil guard, municipalities, representants of the autonomous regions, local and regional crisis management managers from different French and Spanish entities, etc. At the end of the exercise, a joint analysis was made of the strengths and weaknesses found during the development of the exercise and propositions of improvements were made. Local and regional authorities concluded that, thanks to the exercise, they are better prepared to deal with georisks induced by extreme weather, mainly landslides and rockfalls. The scientific community understood the type of operational products they should develop for decision support during disaster risk crises. This experience reinforces the need to create stronger links between the scientific community and civil protection stakeholders.
Earthquakes and freeze-thaw cycles are two important causes of landslides, but knowledge of their combined effect is limited. Therefore, a freeze-thaw test and large-scale shaking table tests were carried out to simulate the progressive deformation and failure mode of loess fill slopes. The process of frost-heaving deformation and seismic deformation was observed, and the failure mode was analyzed by comparing with the accelerations. The results showed that the slope stability decreased after freeze-thaw cycles. Freezing and thawing causes the crest and upper portion melted, and settled to the lower portion, creating frost-heaving zones and irreversible cracks. Comparisons between the freezing-thawing slope and nonfreezing-thawing slope allowed to highlight, through the analysis of seismic responses, the possible and not negligible effect of both frost-heaving spatial distribution of slope surface soil and freeze-thaw interface during the seismic shaking in initiation and development of landslides. The peak ground acceleration (PGA) amplification factors of freezing-thawing slope were higher, especially in the frost-heaving zones. Cracks in freezing-thawing slope developed faster and deformation was greater. The freeze-thaw interface became a potential slip surface and a multistep landslide suddenly occurred under 1.2 g seismic loads, while the nonfreezing-thawing slope was stable. The freezing-thawing slope shows a brittle superficial shear failure, and its failure mode is freeze-thaw cycles - forming potential sliding surface and irreversible cracks - slow expansion of cracks - rapid development and penetration of cracks - superficial shear sliding.
This work aims at investigating the fracture and instability behaviors of Xinjiang granite containing hole and fissures under freeze-thaw (FT) and cyclic loads using acoustic emission (AE) monitoring and X-ray computed tomography (CT) imaging. The stress path is sinusoidal load with decreasing frequency and increasing amplitude pattern. The experimental results reveal a sudden increase of volumetric strain and a sudden decrease of AE-b value. Their increasing rate becomes quick as cycle increases reflecting the rapid propagation of damage. The frequency of AE activities displays different proportions that is impacted by the FT cycle. The percentage of the low-frequency and high-frequency signals is relatively high and low respectively for a rock experiencing more FT cycles. The theoretical description of F-T influence coupled with mechanical performance are performed. Based on acoustic emission energy, a damage evolution model considering the coupling effect of freezing-thawing cycle and cyclic load is proposed, which can fit the experimental data well. A series of CT images reveal the influence of freeze-thaw on rock failure modes. Typical failure modes of double shear coalescence, single shear coalescence and single tensile coalescence failure modes were identified from the reconstructured CT images.
Multistage constant-amplitude-cyclic (MCAC) loading experiments were conducted on Tibet interbedded skarn to investigate and characterize fatigue mechanical behavior of the tested rock. Rock volumetric deformation, stiffness change, and fatigue damage evolution were analyzed along with the macroscopic failure morphology. The experimental results demonstrated that the volumetric deformation of the tested skarn was influenced by the interbed structure. Rock damage presented a two-stage pattern. The rock damage increased quickly at the beginning and subsequently became steady for long periods of time within a cyclic loading stage. A new damage evolution model was proposed on the basis of axial strain. Macroscopic failure morphology analysis revealed different fracture mechanisms, combining a tension-splitting mode, shear-sliding, and mixed shear-tension. In this study, the understanding of the anisotropic mechanical properties of interbedded skarn was highlighted, and this could contribute to the ability to predict the stabilities of rock engineering structures.
This work conducted laboratory tests considering the coupled freeze–thaw (FT) and variable-frequency–variable-amplitude cyclic loads on granite containing two fissures and a circular hole. The analysis is dedicated to reveal the deformation and energy rate characteristics. Testing results show that increasing FT cycle and loading level both accelerate rock damage. The rock subjecting to high FT cycle behaves much larger damage rate in terms of volumetric strain and dissipated energy. The warning strength is defined according to the volumetric strain rate and dissipated energy rate which can early issue a warning than the crack damage stress point. In addition, the rock instability precursor is proposed by monitoring the incremental rate of the radial strain and volumetric strain; drastic damage occurs when the volumetric rate exceeds the radial rate. Three typical crack coalescence modes of double shear coalescence, single shear coalescence, and single tensile coalescence were revealed.
For rock engineering in cold regions, rock is often subjected to coupled fatigue conditions of freeze-thaw (F-T) and stress disturbance. Rock fracture evolution and energy mechanism under room temperature and constant stress amplitude loading condition have been widely investigated. Yet the rock energy dissipation and damage evolution characteristics subjected to multiple level cyclic loading conditions are not well understood. In this work, multiple level cyclic compressive loading experiments were conducted using GCTS RTR 2000 rock mechanics system on marble with F-T treatment of 0, 20, 40 and 60 cycles. The fracture evolution and energy dissipation mechanism were analyzed as well as the damage evolution characteristics. The results indicate that F-T treatment strongly influences the fatigue mechanical behaviors of marble, with both fatigue strength and strain energy decreases and irreversible volumetric deformation increases with increasing F-T cycles. The incremental rate of dissipated energy becomes faster as cyclic loading level grows. In addition, a F-T-fatigue loads coupling damage variable was proposed by using the input total strain energy and the dissipated strain energy to describe the rock damage evolution after F-T treatment and experiencing fatigue loading. Moreover, a damage evolution model was first established based on the obtained coupling damage variable to describe the two-phase damage accumulation characteristics. Damage accumulation curve presents a first steady increase and then faster increase trend, the damage evolution model can good fit the experimental data.
Rock mass containing natural fractures is susceptible to freeze-thaw (F-T) weathering in cold regions and could result in the instability of rock engineering and even serious geological hazards. Yet the F-T action on the change of fracture physical characteristics and the associated fracturing evolution of naturally fractured rock is poorly understood. In this work, multi-level compressive cyclic loading experiments were performed to investigate the fracture evolution of naturally fractured granite using real time acoustic emission monitoring and post-test CT scanning. The results show that the aperture change of natural fracture is related to the fracture openness and filling characteristics, the open-type fracture is sensitive to F-T treatment and its aperture increases faster than the close-type and fill-type fractures. In addition, the stress strain curve pattern is impacted by the initial natural fracture volume. The AE activities at fatigue loading stage are weaker than the stress-increasing stage. The proportion of low frequency AE signals increases with increasing natural fracture volume, and the shear-sliding along natural fracture results in the occurrence of low-frequency signals. Moreover, interactions between the natural fracture and stimulated new fracture are visualized using CT scanning and it is found that the initial natural fracture volume impacts the failure mode and fracture network pattern. The testing results are expected to improve the understanding of the influence of natural fractures on rock damage and deformation in cold regions.
We review the range of landslide processes and provide a vocabulary for describing the features of landslides relevant to their classification for avoidance, control or remediation.
El litoral de la Serra de Tramontana de la Isla de Mallorca está afectado por numerosos procesos de inestabi lidad en las laderas y escarpes que forman la costa. La cala de Banyalbufar, con un acantilado rocoso de más de 50 m de altura, es un ejemplo notable de ello, sufriendo frecuentes desprendimientos como el ocurrido en Septiembre de 1993, el último de importancia, en el que se produjo la caída de una cuña rocosa de unos 80 metros cúbicos de volumen. En este trabajo se analizan los procesos de inestabilidad que afectan a los taludes del acantilado, así como los factores condicionantes y desencadenantes que controlan los desprendimientos. A partir del conocimiento de los mecanismos de rotura y de la caracterización de estos diferentes factores, se rea liza una estimación de la peligrosidad y riesgo en el acantilado, como medida preventiva frente a futuros desprendimientos. La propuesta y diseño de medidas estabil izadoras queda fuera del ámbito de este trabajo, centrado en el aná lisis de los procesos naturales que sufre el acantilado.
Resumen: Entre los días 24 y 29 de marzo del año 1721 tuvo lugar en el Predio de Biniarroi, situado en el t.m de Mancor del Vall (Mallorca), un importante deslizamiento que afectó a unos 300.000 m 2 de tierras de labor, modificando totalmente la topografía original de la zona así como la red superficial de drenaje. Este deslizamiento y reactivaciones posteriores en los años 1816, 1857 y 1943 determinaron el abandono de este núcleo de población y de las tierras de cultivo. Gracias a la recuperación de documentos históricos que refieren los hechos ocurridos por testigos presenciales y al estudio y análisis del terreno, se ha podido reconstruir lo acontecido en el deslizamiento original, sus dimensiones y características, la tipología del movimiento y el mecanismo de rotura, así como los factores que desencadenaron dicho fenómeno. Abstract: Between 24 th March and 29 th March 1721, a great landslide took place in Biniarroi, a small village located in the municipality of Mancor del Vall (Majorca). The landslide affected more than 300.000 m 2 of agricultural land, completely modifying the original topography of the area, as well as the superficial drainage network. The occurrence of this landslide, and subsequent reactivations during the years 1816, 1857 and 1943, caused both the village of Biniarroi and the cultivated area to be abandoned. The recovery of historical documents about this event, including eyewitness accounts, and a detailed study of the area, have allowed us to reconstruct the original landslide, its magnitude and characteristics, the type of movement as well as the triggering factors of this natural phenomenon.
We review rainfall thresholds for the initiation of landslides world wide and propose new empirical rainfall thresholds for
the Central European Adriatic Danubian South-Eastern Space (CADSES) area, located in central and southern Europe. One-hundred-twenty-four
empirical thresholds linking measurements of the event and the antecedent rainfall conditions to the occurrence of landslides
are considered. We then describe a database of 853 rainfall events that resulted or did not result in landslides in the CADSES
area. Rainfall and landslide information in the database was obtained from the literature; climate information was obtained
from the global climate dataset compiled by the Climate Research Unit of the East Anglia University. We plot the intensity-duration
values in logarithmic coordinates, and we establish that with increased rainfall duration the minimum intensity likely to
trigger slope failures decreases linearly, in the range of durations from 20 minutes to ∼12 days. Based on this observation,
we determine minimum intensity-duration (ID) and normalized-ID thresholds for the initiation of landslides in the CADSES area.
Normalization is performed using two climatic indexes, the mean annual precipitation (MAP) and the rainy-day-normal (RDN).
Threshold curves are inferred from the available data using a Bayesian statistical technique. Analysing the obtained thresholds
we establish that lower average rainfall intensity is required to initiate landslides in an area with a mountain climate,
than in an area characterized by a Mediterranean climate. We further suggest that for rainfall periods exceeding ∼12 days
landslides are triggered by factors not considered by the ID model. The obtained thresholds can be used in operation landslide
warning systems, where more accurate local or regional thresholds are not available.
Large numbers of landslides can be associated with a trigger, for example, an earthquake or a large storm. We have previously hypothesized that the frequency-area statistics of landslides triggered in an event are well approximated by a three-parameter inverse-gamma distribution, irrespective of the trigger type. The use of this general distribution was established using three substantially complete and well-documented landslide event inventories: 11,000 landslides triggered by the Northridge California Earthquake, 4000 landslides triggered by rapidly melting snow cover in the Umbria region of Italy, and 9000 landslides triggered by heavy rainfall associated with Hurricane Mitch in Guatemala. In this paper, we examine further this general landslide distribution by using an inventory of 165 landslides triggered by heavy rainfall in the region of Todi, Central Italy. Our previous studies have shown the applicability of our general landslide distribution to events with 4000-11,000 landslides. This smaller inventory provides a critical step in examining the applicability of the general landslide distribution. We find very good agreement of the Todi event with our general distribution. This also provides support for our further hypothesis that the mean area of landslides triggered by an event is approximately independent of the event size.
Analysis of the spatial distribution of rockfall deposits at a regional scale (over an area of 250 km2 of northern Spain) using a cartographic database supported by a Geographic Information System (GIS) reveals several relationships between rockfall activity and environmental variables. Recent rockfall activity is inferred when recent scree is preserved at the bottom of the rock slopes. In order to identify the slope source areas of the scree we have mapped the deposit's drainage basin, applying topographic criteria, and we have combined these basins with the rock slopes map. A method for setting the basin boundaries automatically will replace manual cartography. This method is based on algorithms available within many commercial software programs and originally planned to analyse the behaviour of fluids over a topographic surface.The results obtained by combining the rockfall area source map with the geology and DTM show the relationships between the distribution of rockfall deposits and lithology, elevation and slope of the rockwall and a strong control of the joint type and density. Elevation influence on rockfall has been associated with climatic variations with elevation. Other variables, such as orientation, show complex influences that are difficult to interpret.
Rainfall-triggered landslides taking place in the Spanish Eastern Pyrenees have usually been analysed on a regional scale. Most research focussed either on terrain susceptibility or on the characteristics of the critical rainfall, neglecting a detailed analysis of individual events. In contrast to other mountainous regions, research on debris flow has only been performed marginally and associated hazard has mostly been neglected.
In this study, five debris flows, which occurred in 2008, are selected; and site specific descriptions and analysis regarding geology, morphology, rainfall data and runout were performed. The results are compared with worldwide data and some conclusions on hazard assessment are presented.
The five events can be divided into two in-channel debris flows and three landslide-triggered debris flows. The in-channel generated debris flows exceeded 10 000 m3, which are unusually large mass movements compared to historic events which occurred in the Eastern Pyrenees. In contrast, the other events mobilised total volumes less than 2000 m3. The geomorphologic analysis showed that the studied events emphasize similar patterns when compared to published data focussing on slope angle in the initiation zone or catchment area.
Rainfall data revealed that all debris flows were triggered by high intensity-short duration rainstorms during the summer season. Unfortunately, existing rainfall thresholds in the Eastern Pyrenees consider long-lasting rainfall, usually occurring in autumn/winter. Therefore, new thresholds should be established taking into account the rainfall peak intensity in mm/h, which seems to be a much more relevant factor for summer than the event's total precipitation.
The runout analysis of the 2008 debris flows confirms the trend that larger volumes generally induce higher mobility. The numerical simulation of the Riu Runer event shows that its dynamic behaviour is well represented by Voellmy fluid rheology. A maximum front velocity of 7 m/s was back-analysed for the transit section and even on the fan velocities larger than 2 m/s were obtained.
This preliminary analysis of the major Eastern Pyrenean debris flows represents the first background for future studies. Additional research on other events is necessary to support the results presented herein, and to properly assess and reduce hazard related to debris flows.
Climate and environmental changes associated with anthropogenic global warming are being increasingly identified in the European Alps, as seen by changes in long-term high-alpine temperature, precipitation, glacier cover and permafrost. In turn, these changes impact on land-surface stability, and lead to increased frequency and magnitude of natural mountain hazards, including rock falls, debris flows, landslides, avalanches and floods. These hazards also impact on infrastructure, and socio-economic and cultural activities in mountain regions. This paper presents two case studies (2003 heatwave, 2005 floods) that demonstrate some of the interlinkages between physical processes and human activity in climatically sensitive alpine regions that are responding to ongoing climate change. Based on this evidence, we outline future implications of climate change on mountain environments and its impact on hazards and hazard management in paraglacial mountain systems.
In Italy, rainfall is the primary trigger of landslides that frequently cause fatalities and large economic damage. Using a variety of information sources, we have compiled a catalogue listing 753 rainfall events that have resulted in landslides in Italy. For each event in the catalogue, the exact or approximate location of the landslide and the time or period of initiation of the slope failure is known, together with information on the rainfall duration D, and the rainfall mean intensity I, that have resulted in the slope failure. The catalogue represents the single largest collection of information on rainfall-induced landslides in Italy, and was exploited to determine the minimum rainfall conditions necessary for landslide occurrence in Italy, and in the Abruzzo Region, central Italy. For the purpose, new national rainfall thresholds for Italy and new regional rainfall thresholds for the Abruzzo Region were established, using two independent statistical methods, including a Bayesian inference method and a new Frequentist approach. The two methods proved complementary, with the Bayesian method more suited to analyze small data sets, and the Frequentist method performing better when applied to large data sets. The new regional thresholds for the Abruzzo Region are lower than the new national thresholds for Italy, and lower than the regional thresholds proposed in the literature for the Piedmont and Lombardy Regions in northern Italy, and for the Campania Region in southern Italy. This is important, because it shows that landslides in Italy can be triggered by less severe rainfall conditions than previously recognized. The Frequentist method experimented in this work allows for the definition of multiple minimum rainfall thresholds, each based on a different exceedance probability level. This makes the thresholds suited for the design of probabilistic schemes for the prediction of rainfall-induced landslides. A scheme based on four probabilistic thresholds is proposed. The four thresholds separate five fields, each characterized by different rainfall intensity-duration conditions, and corresponding different probability of possible landslide occurrence. The scheme can be implemented in landslide warning systems that operate on rainfall thresholds, and on precipitation measurements or forecasts.
The autumn of 2004 was particularly wet in Umbria, with cumulative rainfall in the period from October to December exceeding 600 mm. On 4?6 December and on 25?27 December 2004, two storms hit the Umbria Region producing numerous landslides, which were abundant near the town of Orvieto where they affected volcanic deposits and marine sediments. In this work, we document the type and abundance of the rainfall-induced landslides in the Orvieto area, in south-western Umbria, we study the rainfall conditions that triggered the landslides, including the timing of the slope failures, we determine the geotechnical properties of the failed volcanic materials, and we discuss the type and extent of damage produced by the landslides. We then use the recent event landslide information to test a geomorphological assessment of landslide hazards and risk prepared for the village of Sugano, in the Orvieto area. Based on the results of the test, we update the existing landslide hazards and risk scenario for extremely rapid landslides, mostly rock falls, and we introduce a new landslide scenario for rapid and very rapid landslides, including soil slides, debris flows and debris avalanches.
Tree-ring analysis has been used to reconstruct 22 years of rockfall behavior on an active rockfall slope near Saas Balen (Swiss Alps). We analyzed 32 severely injured trees ( L. decidua , P. abies and P. cembra ) and investigated cross-sections of 154 wounds.
The intra-annual position of callus tissue and of tangential rows of traumatic resin ducts was determined in order to reconstruct the seasonality of past rockfall events. Results indicate strong intra- and inter-annual variations of rockfall activity, with a peak (76%) observed in the dormant season (early October ? end of May). Within the growth season, rockfall regularly occurs between the end of May and mid July (21.4%), whereas events later in the season appear to be quite rare (2.6%). Findings suggest that rockfall activity at the study site is driven by annual thawing processes and the circulation of melt water in preexisting fissures. Data also indicate that 43% of all rockfall events occurred in 1995, when two major precipitation events are recorded in nearby meteorological stations. Finally, data on impact angles are in very good agreement with the geomorphic situation in the field.
A total of more than 140 000 kg of small-magnitude rockfall deposits was measured in eight rockfall collectors of altogether 940 m2 in size between 1999–2003 below a 400–600 m high rock face in the Reintal, German Alps. Measurements were conducted with a temporal resolution up to single days to attribute rockfall intensity to observed triggering events. Precipitation was assessed by a rain gauge and high-resolution precipitation radar. Intense rainstorms triggered previously unreported rockfall intensities of up to 300 000 g/(m2h) that we term "secondary rockfall event." In comparison to dry periods without frost (10−2g/(m2h)), rockfall deposition increased by 2–218 times during wet freeze-thaw cycles and by 56-thousand to 40-million times during secondary rockfall events. We obtained three nonlinear logistic growth models that relate rockfall intensity [g/(m2h)] to rainfall intensity [mm/h]. The models account for different rock wall intermediate storage volumes, triggering thresholds and storage depletion. They apply to all rockfall collector positions with correlations from R2=0.89 to 0.99. Thus, the timing of more than 90% of the encountered rockfall is explained by the triggering factor rainfall intensity. A combination of rockfall response models with radar-supported storm cell forecast could be used to anticipate hazardous rockfall events, and help to reduce the exposure of individuals and mobile structures (e.g. cable cars) to the hazard. According to meteorological recordings, the frequency of these intense rockfall events is likely to increase in response to global warming.
From October 2008 to January 2009, Majorca island was affected by a period of intense rainfall and low temperatures which triggered numerous slope movements, 12 being registered in the Tramuntana Range, some of which seriously affected the road network. On the night 19th December 2008, a rockfall on the eastern slope of the Puig de s'Alcadena (Alaro) took place, generating a rock avalanche with a length of 650 m. The rock avalanche destroyed the pine wood in its path, leaving a tongue of blocks over an area of 60.000 m2 and 300.000 m3 in volume. Some of the blocks have a volume of over 1,500 m3 and are several tones in weight. The wedge failure on the scarp of Puig de s 'Alcadena is produced on two planes which coincide with the main tectonic features of the Range. The fact that heavy and continuous rainfall (150 mm in 24 h and 672 mm of accumulated rainfall) coincided with unusually low temperatures (below O0C), was the triggering factor of the avalanche. Fortunately, no serious damage occurred.
This chapter presents a review of the situation concerning the various geomorphological hazards in the country, including some information about existing programmes for research, control and mitigation. With its great variety of climatic, geological and morphodynamic environments, Spain is subject to every kind of natural hazard: tsunamis, floods, volcanism, and mass movements. The whole of the territory is prone to some kind of geomorphological hazard but it is in the eastern and southern coastal strips that the risks are greatest. One of the main problems for the mitigation of geomorphological hazards in Spain is the lack of an appropriate regulatory framework for the incorporation of natural hazard assessments into land-use planning and management at the macro-, meso- and micro-planning levels. The coverage of hazard mapping is still far from complete or adequate, and much work remains to be done. There has been considerable diversity in the methods used for risk assessment and for the cartographic representation of natural hazards. An urgent need is to establish common, accepted methodologies and criteria, based on indicators defined as clearly as possible, and to standardize map legends and scales for different planning levels. Information programmes for the general public also need to be considerably expanded.
RESUMEN La ladera de la margen izquierda del Torrente de Fornalutx, junto al Valle de Sóller en la isla de Mallorca, ha sufrido una serie de movi-mientos en los años 1924, 1954, 1974 y 2002, todos ellos desencadenados por episodios de lluvias intensas y prolongadas durante varios días. En el año 2002, la posibilidad de taponamiento del torrente por la masa deslizada, puso en alerta a las autoridades de la isla y con-dicionó la realización de un estudio detallado de la zona. Este estudio incluyó la realización de perfiles geofísicos mediante sísmica de refracción y tomografía eléctrica; la ejecución de 4 sondeos mecánicos de reconocimiento, así como numerosos ensayos in situ y de labo-ratorio que tuvieron como objetivo determinar las propiedades hidráulicas y resistentes de los materiales de la ladera. El análisis e inter-pretación de los datos obtenidos pone de manifiesto la existencia de un deslizamiento principal de tipo planar, cuya superficie de rotura coincide con el contacto entre dos tipos de materiales de diferente naturaleza y propiedades resistentes. El deslizamiento (y sucesivas reactivaciones), aunque superficial, involucra un volumen de material de unos 300.000 m 3 y determina que la zona sea una de las de mayor riesgo por este tipo de procesos en la isla, debido a la cercanía del pueblo de Fornalutx. Palabras clave: caracterización geomecánica, deslizamientos, laderas, Mallorca, riesgo Landslides on the left side of the Fornalutx torrent (Majorca, Spain) ABSTRACT The slope on the left hand side of the Fornalutx Torrent, close to the Valley of Soller on the island of Majorca, has been affected by a series of movements in 1924, 1954, 1974 and 2002, all of which were triggered by episodes of intense and continuous rainfall. In 2002, the pos-sibility of the torrent being blocked by the material from the slide, alerted the island authorities to the need for a detailed study of the area. The work included a geophysical study of the slope, using seismic and electrical tomography techniques; the drilling of 4 boreholes as well as numerous in situ and laboratory tests, which aimed to determine the hydraulic and stress properties of the materials of the slope. The analysis of the data obtained clearly shows the existence of a planar main landslide and the breaking surface of which coincides with the contact between two types of materials of different nature and stress properties. The landslide, although very shallow, involves a vol-ume of material of 300,000 m 3 and means that the area is one of those at greatest risk on the island, due to the proximity of the village of Fornalutx.
This paper evaluates the usefulness of press archives as temporal
records of landslides in Asturias, northern Spain. It also shows the
potential for this kind of information in the establishment of
relationships between slope instability events and climatic parameters.
In this way, a search has been made of Asturian regional newspaper
archives, including data from the period between January 1980 and June
1995 (5290 newspapers reviewed). The methodology developed shows some
limitations, due to the low frequency of news items relating to
landslides and the lack of scientific data collected by correspondents.
Moreover, there is a bias towards instability events concerning people,
infrastructures and other human resources. Statistical analysis of 209
news items relating to slope instability is useful to establish the
geological and spatial location of landslides. Fifty-one point two
percent of them are situated in the Central Coal Basin, with a
sedimentary siliceous bedrock. Temporal data are accurate in 83.2% of
the cases. A comparison between climatic and slope instability events
reveals that 79% of the landslides developed during rainfall events,
associated with the monthly 24-h rainfall maximum values. Highest
landslide frequencies are reached in years with more than 1000 mm
rainfall, mainly in December and April.
This study investigates the relationships between climate changes and hillslope evolution in the Dolomites (eastern Alps, Italy), during the Late Quaternary, with particular attention paid to landslide processes. The basic premise is that modifications in landslide frequency may be interpreted as changes in the hydrological conditions of slopes, which are in turn controlled by climate.After the statistical analysis of a data set composed of 73 conventional radiocarbon ages, obtained from 24 landslides, four periods of enhanced landsliding have been identified: I. from 10,700 to 8400cal BP, between Younger Dryas and the Preboreal; II. from 8200 to 6900cal BP, during the older Atlantic; III. from 5800 to 4500cal BP, between Atlantic and Subboreal; and IV. from 4000 to 2100cal BP, between Subboreal and Subatlantic.These periods have been compared with different Lateglacial and Holocene paleoclimatic records, to check the correspondence between periods of enhanced landslide activity and cold and humid spells recognized at different spatial scales. As the records show, in the study areas, slope instability processes can be considered geomorphological indicators of climatic changes and to a certain extent reliable proxies of environmental evolution.
We examined information collected from 395 reports of slope-movement events during about the past 150 years in Yosemite National Park, central Sierra Nevada, California, to identify the most prevalent types of slope movements and their triggering mechanisms. Rock slides and rock falls have been more numerous than debris slides, debris flows, and miscellaneous slumps. Rock falls have produced the largest cumulative volume of deposits. About half of slope movements had unreported or unrecognized triggering events. Earthquakes and rain storms individually accounted for the greatest cumulative volumes of deposits from recognized triggers of all types of historical slope movements; snowmelt, human activities and freeze-thaw conditions accounted for only a small proportion of the volumes from reported triggers. A comparison of the historical and postglacial average annual rates of deposition from slope-movement processes in a portion of the Yosemite Valley indicates that, during the period 1851–1992, slope-movement processes have been producing about half the average rate of deposits than during the past 15,000 years.
The Tramuntana Range on the Island of Majorca has suffered numerous, damaging episodes caused by landslides. The historical inventory of these movements shows a clear correlation between landslide occurrence and intense rainfall. Most of the slides have occurred after short intense storms. The slope movements are mainly shallow failures, debris flows, debris slides and soil slips. Regional hazard assessment is carried out by combining the probability of the landslide rainfall threshold with the landslide susceptibility in the area. The correlation of the known dates of historical landslides since 1956 with rainfall data provided by the rain gauges nearest to the location of the slides, reveals that most of the movements take place when maximum 24-hour rainfall values are around 130 mm or above. This is the triggering threshold considered in the present work. A statistical analysis of intense rainfall has been carried out in the area, using the Gumbel probability distribution function, which allows us to obtain the maximum 24-hour rainfall values that are to be expected for return periods of 5, 10, 25 and 100 years and to locate the areas where the rainfall threshold is exceeded. In order to predict medium-term hazard, we have considered the probability of the occurrence of episodes of intense rainfall, exceeding 130 mm in 24 hours, for a period of 25 years. Prior to this work, a susceptibility study was made on the area, based on the inventory of the movements and the analysis of the different conditioning factors of the instability. A susceptibility map at 1 : 25,000 scale was designed which provides information on the spatial probability of occurrence of the landslides predicted in the area. As our objective was to determine the degree of hazard in the study area, we performed a spatial-temporal superposition on the general map of susceptibility and the probability map of intense rainfall exceeding 130 mm, for a return period of 25 years. This methodology allows us to obtain a hazard map which constitutes a feasible tool for regional hazard assessment.
French
Le Massif de la Tramuntana sur l'île de Majorque a subi de nombreux épisodes dévastateurs du fait de glissements de terrain. L'historique de ces mouvements indique une forte corrélation entre la survenue d'un glissement de terrain et de fortes chutes de pluie. La plupart de ces glissements de terrain sont ainsi survenus à la suite d'intenses orages de courte durée. Les mouvements des versants sont principalement constitués d'effondrements de terrains, avalanches ou glissements de débris, ainsi que d'éboulement des sols. L'une des méthodes d'évaluation des risques régionaux consiste à combiner la probabilité du seuil de chute de pluie avec la sensibilité aux glissements de terrain dans la région. La corrélation entre les dates connues des glissements de terrain historiques depuis 1956 avec les données de chutes de pluie fournies par les pluviomètres situés à proximité des sites des glissements de terrain démontre que la plupart des mouvements ont lieu lorsque les valeurs maximales de chutes de pluie sur une période de 24 heures sont supérieures ou égales à 130 mm. C'est là le seuil de déclenchement pris en compte par la présente étude. Une analyse statistique des fortes chutes de pluie a été menée dans la région, à l'aide de la fonction de distribution de probabilité de Gumbel, qui permet de déterminer les valeurs maximales de chutes de pluie sur une période de 24 heures, à prévoir pour des périodes de récurrence de 5, 10, 25 et 100 ans et permet de localiser les zones où le seuil de chutes de pluie est dépassé. Afin de prévenir le risque pour une zone, sur une période moyenne de temps, nous avons considéré la probabilité de la survenue d'épisodes de fortes chutes de pluie, au-delà de 130 mm en 24 heures, sur une période de 25 ans. Préalablement à la présente étude, une étude de sensibilité a été menée dans cette zone, fondée sur l'inventaire des mouvements et de l'analyse des différents facteurs qui conditionnent l'instabilité. Une carte de sensibilité au 1 : 25.000 a ainsi été conçue, afin de fournir des informations sur la probabilité spatiale de survenue de glissements de terrain dans la région. Dans la mesure où notre objectif était de déterminer le degré de risque dans la zone d'étude, nous avons réalisé une superposition spatio-temporelle sur une carte générale de sensibilité et sur la carte de probabilité de fortes chutes de pluie dépassant les 130 mm, sur une période de récurrence de 25 ans. Cette méthodologie nous permet d'obtenir une carte de risque, qui constitue un outil réalisable d'évaluation des risques dans une zone régionale.
This paper presents results of recent studies on distribution and category of landslides in one section of the Sichuan–Tibet Highway, adjacent to the northern side of the Yarlu Tsangpo Grand Canyon, Tibet, Southwestern China. In the tectonic setting predominated by compression and strike-slipping, active faults are dominant and result in the genesis of the great alpine relief together with fluvial incision and unloading. In this section, with a distance of about 290 km between Ranwu and Lulang, 34 landslides occurred. Among them, the 12 large and super-large landslides comprise the most dangerous part of the highway system to road users over the past 50 years. The landslides usually occurred in slopes comprised of moraine with a large thickness, fluvio-pluvial and lacustrine deposits and fractured rocks. Based on the examination of the physical geography, structural geology, Quaternary geology, stratigraphy and petrography, this paper presents the temporal-spatial distribution of landslides along the section and classification of them into three types with respect to mechanism and composites of landslides. Type 1. Landslide initiated at high elevation and transformed into a distal debris flow damming the river with a long reoccurrence interval
The landslides and rockfalls were studied in this paper from Xiangjiaba to Baihetan in the lower reach of Jinsha river. Their
volume, distribution density and landslide index were studied which indicated that there existed close relationships between
landslides and rockfalls and geological structure, stratum. The fold and faultage influenced on the stability of slope and
offered the geological condition to landslides and rockfalls. The physiognomy controlled their distribution. Slope angles
of landslides were 10°–50° and slope angles of rockfalls were mainly 35°–50° in the valley in the studied area. The results
indicated the geology and physiognomy of distribution area of the landslides and rockfalls in the studied area. They offered
the theoretical foundation to prevent and cure geological disaster and protect the water power engineering.
This paper presents a statistical approach to study the spatial relationship between landslides and their causative factors at the regional level. The approach is based on digital databases, and incorporates such methods as statistics, spatial pattern analysis, and interactive mapping. Firstly, the authors propose an object-oriented conceptual model for describing a landslide event, and a combined database of landslides and environmental factors is constructed by integrating the various databases within such a conceptual framework. The statistical histogram, spatial overlay, and dynamic mapping methods are linked together to interactively evaluate the spatial pattern of the relationship between landslides and their causative factors. A case study of an extreme event in 1993 on Lantau Island indicates that rainfall intensity and the migration of the center of the rainstorm greatly influence the occurrence of landslides on Lantau Island. A regional difference in the relationship between landslides and topography is identified. Most of the landslides in the middle and western parts of the island occurred on slopes with slope angles of 25–35°, while in the eastern part, the corresponding range is 30–35°. Overlaying landslide data with land cover reveals that a large number of landslides occurred in the bareland and shrub-covered area, and in the transition zones between different vegetation types. The proposed approach can be used not only to analyze the general characteristics of such a relationship, but also to depict its spatial distribution and variation, thereby providing a sound basis for regional landslide prediction.
The purpose of this study is to develop and apply the technique for landslide susceptibility analysis using geological structure in a Geographic Information System (GIS). In the study area, the Janghung area of Korea, landslide locations were detected from Indian Remote Sensing (IRS) satellite images by change detection, where the geological structure of foliation was surveyed and analysed. The landslide occurrence factors (location of landslide, geological structure and topography) were constructed into a spatial database. Then, strike and dip of the foliation and the aspect and slope of the topography were compared and the results, which were verified using landslide location data, show that foliation of gneiss has a geometrical relation to the joint or fault that leads to a landslide. Using the geometrical relations, the landslide susceptibility was assessed and verified. The verification results showed satisfactory agreement between the susceptibility map and the landslide location data.
The structural and stratigraphic aspects of the Balearic Islands are described by outlining the geology of the Serra de Tramuntana. This range is part of the southeastern margin of the Valencia trough and has the typical features of thrust tectonic areas. A stratigraphic column, a structural map and three cross-sections show the main features of this range. Thrusts dip to the southeast and are arranged in an imbricate system with a transport direction to the NW. The thrusts recorded involve Upper Paleozoic to Middle Miocene rocks. Imbricates-bearing thin slices and duplexes developed where thin sequences with pronounced competency contrasts exist. Folds are also present: they usually trend NE-SW, except in local areas where they are interpreted as being associated with oblique ramps. Fold axes plunge sub-horizontally and folds face the northwest. Thrust displacements of up to 10 km are deduced from the existence of klippes and windows, and shortening of around 50% is deduced from a comparison of deformed and restored cross-sections. The onset of the main contractional event is pre-Miocene (probably Late Oligocene) in age, but major thrust emplacement occurred during the Middle Miocene.The widespread occurrence of compression structures in the Balearic Islands developed from late Oligocene to Middle Miocene put strong constraints on the models explaining the origin of both the Valencia trough and the Algerian basin. The first must be considered, at least in part, as the Balearic foreland basin and the second could be superimposed on the internal zone of the western Mediterranean orogenic belt.
A chronology of recent landslides in the upper basin of the Llobregat River, Eastern Pyrenees, has been reconstructed from technical reports, field reconnaissance and dendrogeomorphological analysis. The precipitation conditions responsible for triggering and reactivating landslides have been deduced by analysis of rainfall records from two rain gauges located in the area. Two different rainfall patterns relate to landslide occurrence: (i) Without antecedent rainfal