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Correlation between ground failure and soil conditions in Adapazari, Turkey
Abstract
Ground failure in Adapazari, Turkey during the 1999 Kocaeli earthquake (Mw=7.4) was severe. In four central downtown districts, where more than 1200 buildings collapsed or were heavily damaged, hundreds of structures tilted and penetrated into the ground due in part to liquefaction and ground softening. Based on a multi-institutional subsurface investigation program, soil conditions along four lines in which ground failure was surveyed after the earthquake are classified into four generalized subsurface site categories. This classification is primarily based on the presence or absence of shallow and intermediate depth liquefiable soils. Observations of ground failure are found to correlate well with site categories that are susceptible to liquefaction according to current state-of-the-art methods without strict adherence to the Chinese criteria. Soils that liquefied were found to meet the liquid limit and liquidity index conditions of the Chinese criteria. However, soils that liquefied did not typically meet the clay-size condition for liquefiable soils by the Chinese criteria.
... Especially in the studies performed after the Izmit earthquake, it was emphasized that the soil liquefaction triggered the building damage. For this reason, the Sakarya region, a natural laboratory in terms of liquefaction, has been an important data source for theoretical liquefaction studies [26][27][28]. The mentioned liquefaction assessment studies after the earthquake focused on the central Adapazari region and were limited to plot-based studies in some parts of the Sapanca district [29]. ...
... These earthquakes produce effective surface rupture and displacement [35]. The maximum horizontal ground acceleration (amax) in the 1999 Izmit earthquake was measured as 0.41 g [26] at the 5401 Sakarya station. This value was used in this study. ...
... The surface damage predicted areas for the Izmit scenario have concentrated on the Quaternary alluvium in the north and east (riverside) of the study area (Figure 9b). After the 1999 Izmit earthquake, Bakir et al. [56] and Sancio et al. [26] emphasized that the mentioned soft soil deposits played a critical role in the damage. In these locations, LPI≥15 and LSI≥35 values are dominant on the maps. ...
The focus of this study is to examine the soil properties and liquefaction potential of the Erenler center district in a critical tectonic zone that can produce large earthquakes, such as the North Anatolian Fault Zone (NAFZ). In this sense, 40 surface wave measurements and 52 geotechnical drillings were employed. Accordingly, the liquefaction potential index (LPI), liquefaction severity index (LSI), Ishihara boundary (IB) curve, and Ishihara-inspired index (LPIISH) liquefaction approaches from geotechnical and geophysical methods were used as integrated. All liquefaction analyses were examined for two scenarios, Mw: 7.4 1999 Izmit (amax: 0.41 g) and Mw: 7.0 1967 (amax: 0.28 g) Mudurnu. According to the analyses, almost all of the study area showed liquefaction risk in the Izmit scenario. In the Mudurnu scenario, liquefaction risk distribution decreased parallel to acceleration. The LPI, LPIISH, and IB liquefaction risk results for both scenarios support each other. On the other hand, it was determined that the probability of liquefaction was lower in the LSI evaluation. The spatial distribution of the liquefaction potential of the Vs-based and SPT-based LPI assessments had a similar pattern. These results show that the LPI approach, originally SPT-based, can also be calculated based on Vs. In addition, according to Vs30-based (average shear wave velocity at 30 m depth) soil classification criteria, low-velocity character E and D soil groups dominate the Quaternary alluvial basin. This indicates that deformation-induced failures may occur even in areas with a low probability of liquefaction in similar strong ground motions. In addition, the evaluation of liquefaction with many approaches in two different bases within the scope of the study constitutes a novelty for the study area and liquefaction analyses. While performing diversified liquefaction analyses and approaches will contribute to obtaining more reliable soil liquefaction results, more case studies are needed to elucidate these comparisons.
... A large number of reinforced concrete structures, most of which were 3-5 story buildings, penetrated the bearing ground soil and sunk down into the earth or tilted due to liquefaction and loss of soil strength. Most of these buildings also had significant structural damage [2]. ...
... The average shear wave velocity in upper 30 m in soil profile was Vs = 470 m/s. Downtown Adapazari is located around 7 km away from the fault plane (R rup ) [2,13] and because of soft soil conditions, long-period ground motion amplification is expected. The ground motions of the major shock wave which recorded at similar site-to-source distances indicated peak ground acceleration values of 0.3 g-0.4g were reasonable estimates for downtown Adapazari [2]. ...
... Downtown Adapazari is located around 7 km away from the fault plane (R rup ) [2,13] and because of soft soil conditions, long-period ground motion amplification is expected. The ground motions of the major shock wave which recorded at similar site-to-source distances indicated peak ground acceleration values of 0.3 g-0.4g were reasonable estimates for downtown Adapazari [2]. ...
Determination of shear modulus along with damping ratio values in the field when shear strains exceeds those maximum strains obtained from laboratory tests has a crucial importance in the seismic design of structures whose interaction with soil is more pronounced. In this study, shear modulus of undisturbed samples, obtained from Adapazarı city center during drilling works conducted within the scope of the geotechnical investigation following the 1999 Kocaeli earthquake, were determined. Elasticity of undisturbed Adapazarı samples was measured using a cyclic triaxial test rig. The aim is to obtain relationships between the elasticity moduli from the stress–strain relations of specimens in dynamic and static loading setups, and the axial strains following termination of dynamic tests. Minimum and maximum shear moduli were determined for non-plastic soils and for soils with the plasticity index of PI = 40%. The elasticity modulus ratio (EN=20/EN=1) for samples with plasticity index of PI = 40% is higher than those with PI = 20% at the same level of deformation. As the plasticity increases at the same deformation level, both of the Eds/EN=1 and Eds/EN=1 ratios increase. Moreover, seismic performance of a reinforced concrete frame is evaluated for both fixed and soil-structure system. Seismic demand in soil-structure model with the frame and soil profile considered in this study is observed to be higher as compared to fixed-base frames.
... As shown on the right side of the figure, the soils in the upper 7 m of the site would be considered potentially susceptible to liquefaction on the basis of the liquid limit (LL) and water content (w n ) components of the widely used Chinese criteria, which state that the soil is susceptible if LL , 35 and w n /LL . 0.9 [10,11] (the clay fraction component of these criteria is neglected per the recommendations of [11] and observations from the Chi -Chi earthquake). Thus, given the water table depth of 1 m, the critical zone in the profile from the standpoint of liquefaction susceptibility is from 1 to 7 m. ...
... As shown on the right side of the figure, the soils in the upper 7 m of the site would be considered potentially susceptible to liquefaction on the basis of the liquid limit (LL) and water content (w n ) components of the widely used Chinese criteria, which state that the soil is susceptible if LL , 35 and w n /LL . 0.9 [10,11] (the clay fraction component of these criteria is neglected per the recommendations of [11] and observations from the Chi -Chi earthquake). Thus, given the water table depth of 1 m, the critical zone in the profile from the standpoint of liquefaction susceptibility is from 1 to 7 m. ...
... SPT-based liquefaction triggering threshold curve of Youd et al.[9] along with data from a liquefaction site (W-P-C) and a non-ground failure site (W-P -A-E) in Wufeng. Both of these sites are susceptible to liquefaction on the basis of the modified Chinese criteria[10,11].SDEE 2788-2/7/2004-12:03-SPRIYA-109840-MODEL 5 -pp. 1-11 D.B. Chu et al. / Soil Dynamics and Earthquake Engineering xx (0000) xxx-xxx 8 ...
... The soil section was taken from the study of Sancio et al. [56] in which typical soil sections of Adapazari (Türkiye) were created. As a result of the boring and laboratory studies carried out on the area, the generated sections and soil classes are given in Fig. 1. ...
... The city was surrounded by soil liquefaction manifestations during and after the earthquake. By many researchers, the extent of structural damages in Adapazari city after this earthquake has been investigated and the devastating effects caused by the soils there were revealed [56,[58][59][60][61]. In a study, by the aid of a back propagation neural network model, typical cross sections of soils here were predicted [62]. ...
Industrialization and population growth have made surface areas more valuable, thereby the multi-story buildings have become an absolute necessity. At this point, numeric models became the fastest and simplest way to evaluate the response of soils and structures. The issued factor in the current paper is related to the way of transferring the multi-story building loads to an alluvial stratum and evaluate the accuracy of different cases, in order to save time and economy. For load transfer, the first case ( case i) includes uniform distributed load, the second case ( case ii) includes the transfer from the basement columns and walls, and the third case ( case iii) includes modeling the real state of the building. Mainly, all three cases gave close results in terms of settlement magnitudes of 2.21, 1.96, and 1.81 cm, respectively. It was inspected that case (i) showed 12.8% more deformation than case (ii) and 22.1% more deformation than case (iii). However, the situation is not the same for the settlement pattern, and the under-column and corner effects are neglected in uniform load. Additionally, the bending moments, which is a critical parameter for the design of a reinforced concrete foundation, have developed different results. In case (ii) and (iii) a bending moment of 500 kNm/m is observed in the center column, while in case (i) the moments converge to 0. Therefore, this study highlights the importance of outstanding decision making when assessing the load-transferring mechanism in modeling with numerical methods. The necessity of the determination of the convenient load transfer way depending on the parameter that is crucial in the evaluation of the soil–structure interaction comes to the fore with current paper.
... The extensive damage in the center of Adapazarı can be directly related to top soil conditions. Local variations in the characteristics of alluvial sediments in Adapazarı appear to have played an integral role in the occurrence and non-occurrence of soil failure and associated building damage [2][3][4]. These observations revealed that determining the soil properties and taking them into account provides an important contribution to understand the real response of buildings subjected to heavy ground motions. ...
... Also Bol [23] and Seed et al. [24] confirmed that dense/very dense sand layers are available in different depths in Adapazari in the regions where abandoned channels of Sakarya River are encountered. Moreover, Sancio et al. [4] showed that three of four typical sections in Adapazari have these dense/very dense sand layers (Fig. 5). ...
The effects of the basement storey on the seismic behavior of RC buildings built on near-surface alluvial soft soil are studied in this study. Numerical building models with and without a basement and with different numbers of stories are developed. Time-history dynamic analysis of the structure–soil models was performed using the specialized geotechnical software package PLAXIS-2D. In the first phase of the finite element analysis, the settlement on the soil under the static loads of the building was determined. In the second phase, the earthquake responses of RC buildings with and without a basement storey in terms of lateral displacement were examined by considering the determined stresses after the static loading. The results of the numerical models demonstrate that when the height of the RC buildings is increased, the seismic response of RC buildings without basement storey is detrimentally affected.
... Regarding the causes of ground fissures, previous studies have validated that the formation of ground fissures is mainly due to excessive extraction of groundwater, earthquakes, heavy rainfalls, or other activities (Ayalew et al. 2004;Budhu and Adiyaman 2012;Peng et al. 2016;Sancio et al. 2002;Wang et al. 2010). For example, Sancio et al. (2002) investigated the development of ground fissures under earthquake and found that tectonic movements were their primary cause. ...
... Regarding the causes of ground fissures, previous studies have validated that the formation of ground fissures is mainly due to excessive extraction of groundwater, earthquakes, heavy rainfalls, or other activities (Ayalew et al. 2004;Budhu and Adiyaman 2012;Peng et al. 2016;Sancio et al. 2002;Wang et al. 2010). For example, Sancio et al. (2002) investigated the development of ground fissures under earthquake and found that tectonic movements were their primary cause. However, some researchers had different opinions. ...
This paper presents an experimental and numerical study on the dynamic performance of an RC frame structure crossing a ground fissure. Shake table tests were conducted with a 1/15-scale model of an RC frame structure crossing a ground fissure and the same structure on unfissured ground under earthquake excitations. Both surface and bedrock waves were taken into account in the study. Dynamic characteristics and seismic responses of the structure were recorded. Using LS-Dyna software, numerical analyses were conducted to investigate the influence of ground fissure on the structure considering the soil-structure-interaction (SSI). Good agreement was observed between the simulation and the test results. The results showed that the presence of a ground fissure changed the propagation characteristics of seismic waves for the common site, formatting the nonuniform excitation for the structure crossing the ground fissure. Moreover, structural members on the hanging wall suffered more serious damage than those on the footwall, because the dynamic amplification effect of the hanging wall was greater than that of the footwall. It was also found that the uneven settlement caused by the ground fissure moderately increased the seismic response of the structure. Furthermore, the settlement had a limited influence on the structural response, but the synthesis of the settlement and the earthquake had a more evident influence on it.
... This kind of study is called the site amplification. There are some investigators who have surveyed the effect of local site conditions on structure defects in literature [Çetin et al. 2002;Tezcan et al. 2002;Sancio et al. 2002;Ozel and Sasatani 2004;Fırat et al. 2009]. Pertinent investigations have revealed that site effects may be noticed to detect the behaviour of structures under the effect of the seimic load. ...
... Basic judgement of site data offers that type and width of buildings has no clearly affect the degree of ground defects. Neverthless, localization of noticed displacements around structures, the relatively scarce notice of liquefaction in around, and the higher rate of strong ground defects for higher structures offers that ground strains joined with soil-structure interaction could have contributed to the triggering and intensity of ground defect [Sancio et al., 2002]. ...
The book is addressed to the scientists connected with construction project management discipline as well as to those who are responsible for creating risk registers for construction projects. A presented matter can become a source of inspiration for the academics involved in the optimization processes in the building sector and for those who are looking for some new solutions and more efficient management strategies for construction projects.
... Bray and Stewart, 2000) and follow-on studies (e.g. Sancio et al., 2002), clearly found ample evidence of liquefaction and ground softening at sites where critical soil layers contained more than 15% particles finer than 5 mm. As suggested in Bray et al. (2001), Sancio et al. (2002), and Sancio et al. (2003), the percent "clay-size" criterion of the Chinese criteria and Andrews and Martin (2000) criteria is misleading, because it is not the percent of "clay-size" particles that is important. ...
... Sancio et al., 2002), clearly found ample evidence of liquefaction and ground softening at sites where critical soil layers contained more than 15% particles finer than 5 mm. As suggested in Bray et al. (2001), Sancio et al. (2002), and Sancio et al. (2003), the percent "clay-size" criterion of the Chinese criteria and Andrews and Martin (2000) criteria is misleading, because it is not the percent of "clay-size" particles that is important. Rather, it is the percent of clay minerals present in the soil and their activity that are important. ...
... It was observed that free fields far from the residential regions are less prone to liquefaction while the regions with tall and heavy buildings are much more susceptible to be liquefied [9]. ...
... Also, the C S correction is applied if the standard sampler is not used. Using the untypical sampler without liners causes shaft friction reduction which 9 reduces the penetration resistance, thus an increasing multiplier of C S in ranges of 1.1 to 1.3 is applied (Eq.14) [12]. ...
... Turkey. [1][2][3][4][5][6][7][8] It is commonly known that the earth fissure hazards are caused by excessive exploitation of underground water and other tectonization activities such as earthquakes. [9][10][11][12] These earth fissures lead to damages of the buildings, farmland destruction, road deformation, and pipeline rupture, which seriously affected people's lives, factory production, and safety. ...
... To avoid distortion of the model behavior, scale factors of the model soil were determined on the basis of Buckingham π law as indicated in Equation (1). ...
To investigate the behavior of a reinforced concrete (RC) frame structure across earth fissure under strong earthquake, a series of shaking table tests on a scaled model were designed and conducted. Three earthquake motion records were selected as input excitations, and the Jiangyou motion has a dramatically greater dynamic effect on the structure mainly due to its inherent rich low‐frequency component. The structural acceleration amplification factor gradually decreased as the peak ground acceleration of input motions increased, implying the progressive degradation of the structure stiffness. The results indicated that the earth fissure site has amplification effect on acceleration of the soil, and the displacement response of frame across the earth fissure was different to that of a typical RC frame structure. The ground floor was the most vulnerable story of the RC frame across the earth fissure.
... Bu doğrultuda da 20,000'den fazla can kaybı yaşanmıştır. Deprem sonrası yapılan araştırmalar basen içerisinde bazı alanlarda 5 m'ye yakın bir yer değiştirmenin olduğu [2,3] ve zeminde meydana gelen sıvılaşmanın etkisinde [5,6,7,8] yapılarda, yıkımın yanında yan yatma ve ötelenme meydana geldiği gözlenmiştir. ...
... Bunlaradan kuvaterner yaşlı çakıllı ve siltli kum içeren alüvyon malzeme, Adapazarı bölgesinin büyük bir bölümünde gözlenmektedir. Bölgedeki bu alüvyon istif Sakarya ve Mudurnu nehirlerinin taşıdığı malzemeden oluşmuştur [5]. Havza içerisindeki sedimanlar kil, silt, kum ve çakıl ardalanmaları şeklinde görülebileceği gibi bazen tek başına belirli bir seviyede yer alabilmektedir [4,7]. ...
Deprem esnasında zemin davranışının önceden kestirilmesi, olası bir depremde meydana gelecek can ve mal kayıplarını en aza indirgemede oldukça önem arz etmektedir. 17 Ağustos 1999 İzmit (Mw=7.4) ve 12 Kasım 1999 Düzce (Mw=7.2) depremleri Adapazarı bölgesinde önemli miktarda yapı hasarına ve beraberinde çok sayıda can kaybına neden olmuştur. Özellikle İzmit depremi sonrası Adapazarı bölgesinde yapılan çalışmalar, zemin özelliklerinin etkisiyle bölgede bazı alanlarda yapısal hasarın yanında yapılarda batma ve dönme meydana geldiğini göstermiştir. Bu nedenle Adapazarı ovasında zemin özelliklerinin belirlenmesi önem kazanmıştır. MASW tekniği sığ tabakalara ait kayma dalgası hızını elde etmede geliştirilmiş bir yöntemdir. Yöntem Arifiye ilçesinin zemin özelliklerinin belirlenmesi ve olası sıvılaşma alanlarının tespitinde kullanılmıştır. Bu doğrultuda toplamda 37 noktada veri kazanımı gerçekleştirimiş ve herbir noktanın bir boyutlu derinlik-kayma dalgası hızı belirlenmiştir. Hız bigileri dikkate alınarak 5-10-15-20-25-30 m derinlik seviyesine ait ortalama Vs kat haritaları hazırlanmıştır. Bu veriler neticesinde zemin sınıflaması ve olası sıvılaşma alanları tespit edilmiştir.
... Bray and Stewart, 2000) and follow-on studies (e.g. Sancio et al., 2002), clearly found ample evidence of liquefaction and ground softening at sites where critical soil layers contained more than 15% particles finer than 5 mm. As suggested in Bray et al. (2001), Sancio et al. (2002), and Sancio et al. (2003), the percent "clay-size" criterion of the Chinese criteria and Andrews and Martin (2000) criteria is misleading, because it is not the percent of "clay-size" particles that is important. ...
... Sancio et al., 2002), clearly found ample evidence of liquefaction and ground softening at sites where critical soil layers contained more than 15% particles finer than 5 mm. As suggested in Bray et al. (2001), Sancio et al. (2002), and Sancio et al. (2003), the percent "clay-size" criterion of the Chinese criteria and Andrews and Martin (2000) criteria is misleading, because it is not the percent of "clay-size" particles that is important. Rather, it is the percent of clay minerals present in the soil and their activity that are important. ...
Over the past decade, major advances have occurred in both understanding and practice with regard to assessment and mitigation of hazard associated with seismically induced soil liquefaction. Soil liquefaction engineering has evolved into a sub-field in its own right, and engineering assessment and mitigation of seismic soil liquefaction hazard is increasingly well addressed in both research and practice. This rapid evolution in the treatment of liquefaction has been pushed largely by a confluence of lessons and data provided by a series of major earthquakes over the past dozen years, as well as by the research and professional/political will engendered by these major seismic events. The overall field of soil liquefaction engineering is now beginning to coalesce into an internally consistent and comprehensive framework, and one in which the various elements are increasingly mutually supportive of each other. Although the rate of progress has been laudable, further advances are occurring, and more remains to be done. As we enter a “new millenium”, engineers are increasingly well able to deal with important aspects of soil liquefaction engineering. This paper will highlight a number of important recent and ongoing developments in soil liquefaction engineering, and will offer insights regarding research in progress, as well as suggestions regarding further advances needed.
... Site investigations have revealed the presence of special geological formations featured by laminar stratigraphy structures consisting of alternating interlayered soils with distinct properties in both terrestrial and marine sedimentation conditions [38]. Examples include i) Christchurch silty soil deposits in New Zealand [4,5,8], ii) interbedded clays, silts, and sands in Turkey [6,28], iii) Yangtze River floodplain deposits in China [35], iv) laminated soil in South China Sea [19], and v) varved clay at Connecticut Valley, USA [14], in northern Sweden [25], and in Poland [30]. ...
Stratified soil is a type of widely distributed special soil, consisting of alternating interlayered soils with distinct properties in both terrestrial and marine sedimentation conditions. It is endowed with anisotropic physical properties and mechanical behavior by its unique laminar structure features. So far, its mechanical behavior has not been fully understood. To systematically investigate the laminar structure effects of stratified soil, artificially prepared stratified soil samples of silty clay interlayered by silty sand were studied. First, the laminar structure features of stratified soil in Yangtze River floodplain deposits at Nanjing, China, were summarized. Then, based on the laminar structure features, preparation method for stratified soil samples was proposed by stacking soil layers one by one, which was basically an integration of soil paste plus consolidation method for silty clay layer preparation and water pluviation plus freezing method for silty sand layer preparation. After verification of the sample preparation method, a series of consolidated-undrained triaxial compression tests were carried out to study the mechanical behavior of stratified soil. The effects of thickness of constituent layers, consolidation conditions (isotropic or anisotropic consolidation), and loading paths (conventional triaxial compression, constant-p compression, and lateral extension) were investigated. The results show that the mechanical behavior of stratified soil (including stress–strain curves, excessive pore pressure accumulation, sample failure modes, and strength index) generally falls in between the behavior of the two constituent layers of soil, i.e., a normally consolidated silty clay and a medium-dense silty sand. The silty clay layer thickness (with fixed silty sand layer thickness), consolidation conditions, and loading paths together determine the stratified soil behavior, either silty sand dominant or silty clay dominant. Laminar structure can improve volumetric dilation trend and thus increase undrained shear strength of stratified soil. The presence of silty clay layer would suppress shear banding development in stratified soil. The strength of stratified soil can be underestimated by experiments using disturbed or remolded samples where the laminar structure is partially or completely lost.
... Further finer, the determination of the liquefaction susceptibility of finegrained soils uses the grain size distribution curve, plasticity chart, and Chinese criteria for the liquefaction of clayey soils [1,7]. However, the Chinese criteria and Andrews and Martin [1] criteria do not seem to be reliable as screening tools because the activity of clay minerals present in the soil matrix rather than the ''clay size'' particle fraction plays a critical role in the determination of liquefaction potential [7,39]. ...
This study aims to assess the liquefaction potential of soil deposits where soil boiling and liquefaction have been first observed since the Pohang earthquake in 2017. We use multi-physics techniques for site characterizations and laboratory analysis for in situ soil samples. Depth-dependent engineering soil properties are analyzed using effective stress–depth models, where extensive datasets compiled from previous studies enhance data reliability. A physics-inspired and data-driven framework successfully establishes a lower bound for low plastic clay and upper bound for loose silt for porosity, electrical resistivity, and shear wave velocity data and divides the sediment into four different soil layers. In particular, there may exist a transitional zone from loose silt to low plastic clay (i.e., depth z = 4–10 m), where the silt tends to be contractive when subjected to cyclic events and plays a critical role in the determination of time to pore pressure dissipation, so that this layer may be sensitive to liquefaction. The factor of safety is calculated based on the field test results to verify the liquefaction potential of fine-dominant sediments where clays prevail. The data interpretation approach and physical model framework proposed in this study can be applied to the evaluation of liquefaction susceptibility for fine-dominant soil deposits.
... g as suggested by previous studies (e.g. Sancio et al. 2002;Yakut et al. 2005). Following the 1999 Kocaeli earthquake, the municipality of the Adapazari performed a damage assessment for the buildings in the city . ...
While earthquakes can have a devastating impact on the economic growth and social welfare of earthquake prone regions, probabilistic seismic risk assessment can be employed to assess and mitigate such risks from future destructive events. In a previous study (Sianko et al. in Bull Earthq Eng 18:2523–2555, 2020), a probabilistic seismic hazard analysis (PSHA) tool based on the Monte-Carlo approach, was developed to predict the seismic hazard for high seismicity areas. In this study, a seismic risk assessment framework is developed incorporating the previously developed PSHA tool, with vulnerability functions based on various damage criteria, exposures and casualty models. Epistemic uncertainty is addressed using logic trees and distribution functions. The developed seismic risk assessment framework can estimate human and economic losses for particular return periods using an event-based stochastic procedure. The framework is applied to a case study area, the city of Adapazari in Turkey. Seismic risk assessment is carried out for different return periods to identify the most vulnerable areas of the city. The verification of the developed seismic risk framework is performed by comparing the predicted seismic losses to those observed during the 1999 Kocaeli earthquake that severely affected the city of Adapazari. The results of the study indicate that while overall predictions for extensive and complete damage states demonstrate strong correlation with the observed data, accurate risk predictions at the district level are not achievable without microzonation studies.
... Sancio ve diğ. [28], Adapazarı kent merkezinde, zemin problemlerinin olduğu bölgelerde ve yıkım oranlarının yüksek olduğu eksenler boyunca, toplam 46 noktada sondaj ile birlikte Standart Penetrasyon testi (SPT) ve 135 noktada Koni Penetrasyon testi (CPT) yapmışlar ve çalıştıkları alanlardaki üst 15 m için dört farklı tipte zemin profili sunmuşlardır (Şekil 1). Şekil 1'deki kesitler incelendiğinde, kalınlığı 6 m'yi bulan sıkı kum ve çakıllı kumların varlığı gözlemlenmektedir. ...
Depremler sırasında yumuşak alüvyon zeminlerin bulunduğu bölgelerde sıvılaşma kaynaklı hasarlar meydana gelebilmektedir. Bu nedenle bu çalışma, alüvyon kökenli Adapazarı zeminlerini temsil eden tipik bir kesitin sıvılaşma potansiyelinin sayısal analiz yardımıyla değerlendirilmesini konu almaktadır. Analizler, Plaxis 2D yazılımı ile yürütülmüş, zemin kesiti ise UBCSAND malzeme modeli ile modellenmiştir. Ek olarak, sıvılaşma potansiyeli yüksek olan Adapazarı zemin kesitinde, zemin iyileştirmesinin sıvılaşmaya karşı etkisinin belirlenebilmesi adına, yapı yükü uygulanması halinde ve yapı altında jet-grout kolonlarının modellenmesi durumlarında analizler tekrar edilmiştir. Deprem verisi olarak 1999 Marmara Depremi kullanılmıştır. Yapılan analizler sonucunda belirli analiz noktaları seçilerek, bu noktalardaki ivme-zaman, deplasman-zaman ve boşluk suyu basıncı değişimleri incelenmiştir. Söz konusu analiz noktalarında maksimum ivme değerleri incelendiğinde, bazı noktalarda sıvılaşmanın sönümlenememesi ile zemin büyütmelerinin yaşandığı gözlemlenmiştir. Deplasman-zaman değişimlerinde ise iyileştirmenin yatay deplasmanları %59 değerine kadar azalttığı belirlenmiştir. Ek olarak, iyileştirmenin olmadığı durumda boşluk suyu basınçlarının toplam gerilmeye ulaştığı ve sıvılaşmanın gerçekleştiği; iyileştirme durumunda ise boşluk suyu basınçları toplam gerilmeye ulaşmadığından sıvılaşmanın önüne geçildiği gözlemlenmiştir. Sonuçlara dayanarak, modelin sıvılaşma davranışını temsil edip etmediğinin daha detaylı tartışılması gerektiği belirlenmiştir.
... These earthquakes caused effective surface damage and displacement around the study area (Ambraseys and Zatopek 1969, Barka et al. 2002;Müller et al. 2003). On the other hand, the effects of local ground conditions on damage were emphasized in the studies conducted after the 1999 Izmit earthquake (Sancio et al. 2002, Bray et al. 2004. For this reason, these two earthquakes were determined as scenario earthquakes in the ground response analysis. ...
The strong ground motion effect is amplified or de-amplified due to the change in subsoil condition. Local soil properties prediction is critical for earthquake-safe areas and the earthquake hazard assessment of existing structures. This study was carried out with time-domain 1D Nonlinear analysis to understand the soil response characteristics of the Arifiye district. In this sense, geotechnical drilling at 47 points and surface wave analysis at 44 points were performed. Site response profiles in the study area were analyzed with the DeepSoil program for Mw:7.0 1967 Mudurnu and Mw:7.4 1999 Kocaeli earthquake scenarios. Peak spectral acceleration (Pga) and spectral acceleration (Sa) values were determined in the analysis of the Mudunu scenario as 0.11–0.24 g and 0.44–1 g, respectively. The Kocaeli scenario’s Pga and Sa distribution were obtained in a wide range of 0.2–0.56 g and 0.47–2.3 g, respectively, compared to the Mudurnu scenario. Especially in the Mw:7.4 model, high Pga (> 0.3 g) and Sa (> 1 g) values were obtained in the uncemented units located north of the study area. Kocaeli scenario results showed that the spectral accelerations at the surface in soil groups D and E were higher than the Turkish Building Earthquake Code building requirements. It is necessary to update the earthquake design spectra site-specific. The results clearly showed the effect of ground conditions and strong ground motion selection on earthquake-resistant building design.
... as suggested by previous studies (e.g. Sancio et al., 2002;. ...
While earthquakes can have a devastating impact on the economic growth and social welfare of earthquake prone regions, probabilistic seismic risk assessment can be employed to assess and mitigate such risks from future destructive events. In a previous study (Sianko, 2020), a probabilistic seismic hazard analysis (PSHA) tool based on the Monte-Carlo (MC) approach, was developed to predict the seismic hazard for high seismicity areas. In this study, a seismic risk assessment framework is developed incorporating the previously developed PSHA tool, with vulnerability functions based on various damage criteria, exposures and casualty models. Epistemic uncertainty is addressed using logic trees and distribution functions. The developed seismic risk assessment framework can estimate human and economic losses for particular return periods using an event-based stochastic procedure. The framework is applied to a case study area, the city of Adapazari in Turkey. Seismic risk assessment is carried out for different return periods to identify the most vulnerable areas of the city. The verification of the developed seismic risk framework is performed by comparing the predicted seismic losses to those observed during the 1999 Kocaeli earthquake that severely affected the city of Adapazari. The results of the study indicate that while overall predictions for extensive and complete damage states demonstrate strong correlation with the observed data, accurate risk predictions at the district level are not achievable without microzonation studies.
... Although many studies have been conducted on the liquefaction of sands, studies on fine-grained soils' liquefaction are relatively few. As a result of the liquefaction of silt soils in Adapazarı, especially in the 1999 Kocaeli earthquake, studies in this direction began to intensify in Turkey (Sancio et al., 2002;Bray et al., 2004;Bol et al., 2010). ...
Since soil liquefaction is a dimension that increases the amount and severity of losses in an earthquake, it is vital to estimate the liquefaction potential accurately. Traditionally, several analytical inferences were made for the prediction of soil liquefaction. However, it is necessary to use machine learning methods to establish nonlinear relationships of soil physical characteristics and develop an accurate classification model. In this study, the applicability of seven different machine learning algorithms; decision trees, logistic regression, support vector machines, k-nearest neighbors, stochastic gradient descent, random forest, and artificial neural network, were investigated on a data set obtained from field experiments (Standard Penetration Test) on soils in Adapazari region after the 1999 earthquake. Performance metrics such as accuracy, recall, precision, F1 score, and receiver operating characteristic evaluated algorithms. As a result of experimental studies, the decision tree algorithm performed best on the dataset, with an overall accuracy of 90%. The decision tree model provides an easy and effective tool for evaluating ground liquefaction potential to decision-makers. As a result of the decision tree study, it was observed that the mean grain size (D50) soil feature has the most significant effect on the liquefaction potential.
... The Kocalei earthquake occurring on August 17, 1999 affected in various ways many constructions in the city of Adapazari, Turkey. Following observers, some buildings sank vertically into the soil, others tilted, and some even suffered lateral translation over the ground [1][2][3]. This case illustrates well the diversity of damage that earthquake fluidization of soils may cause to man-made structures [4]. ...
We study the behavior of cylindrical objects as they sink into a dry granular bed fluidized due to lateral oscillations. Somewhat unexpectedly, we have found that, within a large range of lateral shaking powers, cylinders with flat bottoms sink vertically, while those with a ''foundation'' consisting in a shallow ring attached to their bottom, tilt besides sinking. The latter scenario seems to dominate independently from the nature of the foundation when strong enough lateral vibrations are applied. We are able to explain the observed behavior by quasi-2D numerical simulations, which also demonstrate the influence of the intruder's aspect ratio. The vertical sink dynamics is explained with the help of a Newtonian equation of motion for the intruder. Our findings may shed light on the behavior of buildings and other man-made constructions during earthquakes.
... Several researchers have analyzed well-documented case histories after major earthquakes, offering valuable evidence on the effects of soil liquefaction on the response of real structures. Sancio et al. 4 studied several cases from the 1999 Kocaeli earthquake, which led to severe damage or even toppling collapse of a multitude of buildings in Adapazari. It was concluded that taller buildings (with a larger number of storeys) were observed to accumulate larger settlement and rotation. ...
This paper studies the effect of structure–soil–structure interaction (SSSI) on the seismic response of neighboring structures with shallow foundations on liquefiable sand. The problem is studied through coupled hydromechanical analyses. Nonlinear soil response is modeled with PM4Sand, calibrated on the basis of soil element tests of Hostun sand. The numerical methodology has been compared against six centrifuge model tests, showcasing its ability to predict the settlements. Three idealized structures of width B are considered, of different aspect ratio and foundation bearing pressure q, founded on two liquefiable layer depths, DL/B = 1 and 2. Initially, the response of a single building is studied, offering insights on the developing failure mechanisms. While the settlement increases with q in the case of a deep (DL/B = 2) layer, this is not the case for the shallow (DL/B = 1) layer, where the increased soil confinement leads to the development of a stiffer soil column, which offers increased support to the structure. Pairs of identical structures are subsequently analysed, revealing the effect of SSSI on settlement (w) and rotation (ϑ). While its effect on w is beneficial, its effect on ϑ is detrimental, leading to a dramatic increase compared to the single structure. The detrimental effect of SSSI on θ is shown to be a function of the gap (s/B) between the buildings and the depth of the liquefiable layer (DL/B). In the case of the shallow layer, the two structures rotate away from each other. This is not the case of the deeper layer, where they may either rotate away or towards each other, depending on s/B.
... Ground fissure is classified as a kind of active ground fault that impairs the integrity of the site and may expose itself to ground surface. Owing to crustal movements and human activities, ground fissure has become a common geologic hazard widely distributed all over the world [1][2][3][4]. Research on the ground fissure disasters could be dated back to approximately the beginning of the 19th century [5], and it was found that the ground fissure movement would pose serious threats to engineering structures, such as roads, tunnels, railways, pipelines, underground and surface structures. Subsequently, avoidance measures were proposed for the surface structures within the influence range of ground fissures [6]. ...
To investigate the seismic behavior of underground structures in the ground fissure site, a series of shaking-table tests on a subway station intersecting a ground fissure were carried out. Upon investigating the experimental phenomena and test results, propagation of earthquake waves through the soils with ground fissures was characterized and the damage mechanism of the subway station intersecting the ground fissure under earthquakes was studied. The results revealed that the features of wave propagation in soils with ground fissures were different from those in soils without ground fissures, in terms of the intensity, peak instant, and spectrum components. The movement of the subway station intersecting the ground fissure was better controlled by the surrounding soil with a lower input PGA. However, the response of the subway station and surrounding soil was not coordinated under strong earthquakes due to the ground fissure movement. The strain distribution for structural components was related to the position in the soil, and the strains of structural components were generally larger in the hanging-wall than those in the footwall, which was caused by the wave propagation in the ground fissure site. The damage mechanism of subway station intersecting the ground fissure was characterized by the cracks initially produced in the central columns and rapidly developed due to the coupling effect of the shear deformation, compression and bending moment. The bearing capacity of the central columns decreased rapidly, and then the bending moment and shear force at the connections between the slabs and side walls also exceeded the bearing capacity, resulting in the failure of the subway station.
... The effective stress and mechanical parameters of the soil are significantly affected by the fluctuation of the groundwater level of the islands and reefs [11]. Furthermore, the seismic observations in both field and model tests show that the variation in the groundwater level has an important effect on the ground motion and the degree of earthquake-induced damage to structures since the work of Seed et al. [3,7,39,55]. Recently, Yasuda and Hashimoto [53] studied the relationship between the building damage degree and the groundwater level during the 2011 Great East Japan Earthquake, based on the data from 221 existing boreholes and 23 additional boreholes. ...
The changes in groundwater level in coral islands are more common than those in inland areas. In this paper, a series of shaking table tests were performed to investigate the influence of the groundwater level on the seismic response of a coral sand foundation–superstructure system. The responses of excess pore pressure, acceleration, displacement and bending moment of the model structure were measured and analysed in detail. The results illustrate that owing to the rise in the groundwater level, the natural frequency of the coral ground drops, while the damping ratio increases; in addition, the rising groundwater level has a softening effect on the model ground. Moreover, the excess pore pressure ratios of coral sands increase with rising groundwater level, and the increase in the ratios significantly grows with increasing earthquake strength. The amplification factors of the soil–structure acceleration response decrease with the increase in the groundwater level, regardless of whether the ground motion is weak or strong. Furthermore, both the settlement and horizontal displacements of the model structure increase when the groundwater level rises. In terms of the bending moment, the rise in the groundwater level will reduce the response of the column bending moment irrespective of the earthquake strength.
... In many cases, the differential settlement and tilt of the foundations resulted in the demolition of buildings after the CES ]. Other documented case histories such as the 1999 Kocaeli earthquake in Turkey [Bray and Stewart 2000;Sancio et al. 2002;and Bray et al. 2004] and 2010 Maule, Chile, earthquake [Bray and Frost 2010;Bray et al. 2012] also illustrate the catastrophic nature of liquefaction phenomenon and its adverse effects on the superstructures in urban areas. ...
This study explores utilizing helical piles as a countermeasure to reduce liquefaction-induced foundation settlement and investigates their seismic performance in liquefiable grounds. Two large-scale shake table test series, one without any mitigation measures and one using helical piles, were conducted using the shake table facility at the University of California, San Diego. During each test series, the soil and superstructure models were extensively instrumented and subjected to two consistently applied shaking sequences. The model ground included a shallow liquefiable layer aimed at replicating the subsurface ground conditions observed in the past earthquakes in New Zealand, Japan, and Turkey.
... Zemin alt yapı modelleri oluşturulurken yumuşak zemin literatürden [14] seçilmiş ve bu zeminde bulunan yer altı su seviyesi (YASS) dikkate alınmıştır. YASS etkisi dikkate alınırken zeminlerin elastisite modülleri 1/10 oranında azaltılmıştır. ...
zet Bu çalışmada, yumuşak zeminler üzerine inşa edilen betonarme binaların, bodrum katlı yapılması durumunda göstereceği deprem davranışı incelenmiştir. Bu amaçla, 3-10 katlı yapıların yapı-zemin modeli kurularak, sonlu elemanlar prensibine dayalı olarak çalışan SAP2000 programında, sonlu eleman modeli oluşturulmuştur. Yapı-zemin modellerinin tamamının zaman tanım alanında dinamik analizleri gerçekleştirilmiştir. Dinamik analizlerin sonuçlarına göre her katın temel seviyesine göre göreli kat ötelemeleri grafikler halinde sunulmuş, ayrıca her yapının son kat noktalarının yer değiştirme-zaman grafikleri de sunularak yapı performansları değerlendirilmiştir.
... Increased ' vol at higher ' vc have also been observed in several other laboratory investigations (Lee andAlbaisa, 1974, Wu, 2002). This is further corroborated with field observations of the generally greater settlement of buildings with more stories (Sancio, et al. 2002, Yoshida, et al. 2001. As further illustrated in Figure 9, relatively lower ε' vol were found by Shafiee (Shafiee, 2016) in cyclic DSS tests on an overconsolidated (OCR = 1.75) specimen of Sherman Island peat reconsolidated to ' vc = 100 kPa compared to those of this study. ...
Cyclic shearing behavior, dynamic characteristics, and post-cyclic volume change of a peat sublayer from the Port Lands area of Toronto (Ontario, Canada) are investigated in this study. Laboratory specimens are trimmed from block samples collected from a depth of about 4.0 to 4.5 m. Constant-volume cyclic direct simple shear tests indicate an initial reduction of effective stress with number of stress cycles. However, the corresponding excess pore pressure ratios do not exceed 60%, indicating a cyclic mobility behavior in the peat specimens. Maximum shear moduli of the peat samples are also determined from shear wave velocity measurements. Post-cyclic volumetric strain, as well as the variations of secant modulus, modulus reduction, and damping ratio of the peat, are presented in terms of cyclic shear strain and compared with other studies. Empirical relationships are proposed for characterizing the shear modulus and damping ratio of Toronto peat.
... Bu depremler sonrası farklı disiplinlerdeki bilim adamları söz konusu hasarların nedenlerini araştırmışlardır. Bazı bilim adamları bu yıkıcı hasarlar üzerinde zeminin çok önemli etkisi olduğunu savunmuşlar [2][3][4][5]. Diğerleri ise yapısal elemanlardaki ve/veya tasarım yöntemindeki bazı eksiklerden kaynaklandığını belirtmişlerdir [6][7][8][9][10]. 1999 depremlerinin öğrettikleri ve gözlemleri ışığı altında halen birçok çalışma gerçekleştirilmektedir. ...
ÖZET Deprem yönetmelikleri teknik literatürdeki gelişmelere bağlı olarak belirli aralıklarla güncellenmekte ve değiştirilmektedir. Deprem yönetmeliklerindeki bu güncelleme ve değişiklikler genellikle tasarım yöntemleri üzerinde yapılmaktadır. Bu makalede, istinat duvarlarına ilişkin Türkiye Depreme Yönetmeliği ve Eurocode-8'de önerilen tasarım yöntemleri karşılaştırma için dikkate alınmaktadır. Bu çalışmanın temel amacı istinat duvarlarının depreme göre tasarımında anılan yönetmeliklerdeki farklılıkları incelenmektedir. Bu inceleme istinat duvarlarının tasarımında kullanılan sözkonusu deprem yönetmeliklerindeki bağıntılarla yapılmaktadır. Elde edilen bulguların tartışılmasıyla bahsedilen deprem yönetmeliklerindeki tasarım yöntemlerinin önemli farklılıkları tablolarda ve şekillerde özetlenerek verilmekte ve böylece bazı sonuçlar ve öneriler getirilmektedir. Bu bulgulardan elde edilen sonuçlar, Türkiye Deprem Yönetmeliğine göre istinat duvarlarının depreme göre daha emniyetli tasarımları için tepki (tasarım) spektrumlarındaki zemin parametrelerinin dikkate alınması gerektiğini ortaya koymuştur. ABSTRACT Earthquake codes have been periodically revised and updated depending on the technical literature improvements. This revises and update in earthquake codes has been generally performed on the design methods. In this paper, the design methods which recommended Turkish Earthquake Code and Eurocode-8 related to retaining walls are considered for comparison. The main purpose of this study is to investigate differences in the aforementioned codes in the design according to earthquake of retaining walls. These investigate done with relation in the as mentioned earthquake codes used in the design of retaining walls. The important differences of design methods in the mentioned earthquake codes by discuss of obtained findings are briefly given in tables and figures and thus some conclusions and recommendations are brought. The results obtained from this findings revealed that, should be considered of soil parameters in the response (design) spectrums for the safer designs according to earthquake of retaining walls according to Turkish Earthquake Code.
... Increased ' vol at higher ' vc have also been observed in several other laboratory investigations (Lee andAlbaisa, 1974, Wu, 2002). This is further corroborated with field observations of the generally greater settlement of buildings with more stories (Sancio, et al. 2002, Yoshida, et al. 2001. As further illustrated in Figure 9, relatively lower ε' vol were found by Shafiee (Shafiee, 2016) in cyclic DSS tests on an overconsolidated (OCR = 1.75) specimen of Sherman Island peat reconsolidated to ' vc = 100 kPa compared to those of this study. ...
The presence of organic fibers can induce a very different cyclic liquefaction behaviour in organic soils and peat deposits, compared to that of granular cohesionless soils. This paper investigates the cyclic shearing response and liquefaction behaviour of undisturbed peat samples, collected from a depth of about 4.0 to 4.5 m at the Port Lands area of Toronto, Ontario, Canada. The peat samples contain high water contents (ranging from 180 to 237%) and organic contents (ranging from about 42 to 60%, including a fiber content of 20 to 30%), which are important factors in the shearing behaviour of peat. The cyclic stress-strain, liquefaction, and post-cyclic behaviours of these samples are examined using stress-controlled cyclic direct simple shear tests. Cylindrical samples are trimmed from large block samples of peat and then subjected to different consolidation vertical stresses and cyclic shear loads in these tests. Undrained shearing is replicated by maintaining a constant-volume condition during cyclic shearing. Because of the laterally confined boundary condition with no initial shear stress, the experimental results are applicable to in-situ level-ground conditions below the phreatic surface where liquefaction can occur. The stress-strain behaviour of Toronto peat shows an accumulation of excess pore pressure with the number of stress cycles. The equivalent excess pore pressure ratios remain essentially below 60%, indicating a cyclic mobility type of behaviour in the peat samples. Despite the relatively low excess pore pressures, the cyclic shear strains accumulate to large values with repeated cycles of loading. Large cyclic shear strains could compromise the performance and serviceability of a structure overlying a peat deposit. The results further indicate a more significant effect of the effective overburden stress on the cyclic liquefaction resistance of Toronto peat compared to those found from cyclic triaxial tests on inorganic cohesionless soils. Post-earthquake settlement behaviour of Toronto peat samples is also presented in terms of post-cyclic volumetric strain. It is found that the post-cyclic volumetric strain increases with increasing the level of cyclic loading, cyclic shear strain, and effective vertical stress. However, the strong relationship between the post-cyclic volumetric strain and shear strain is not unique and depends on the effective overburden pressure.
... This table consists of soil relative density D r , mean particle diameter D 50 , fine content FC, modified SPT number (N 1 ) 60 , and soil friction angle φ. Some parameters (relative density or SPT number, mean particle diameter, fine content) were taken from the literature (Adachi et al. 1992;Ishihara and Yoshimine 1992;Sancio et al. 2002). Values of the relative density and (N 1 ) 60 were correlated using the following equation (Kulhawy and Mayne 1990): ...
Assessment of liquefiable soils strength is a challenging task in engineering practice especially when a structure is founded on top of the liquefied soil. While it has been addressed and studied in the literature, the lack of practically feasible approaches to calculate the bearing capacity of soil in such a condition is tangible. In this study, simple analytical equations have been proposed to calculate the bearing capacity of liquefiable soils under shallow foundations. The equations have been developed for two cases, separated based on the thickness of liquefiable soils and width of foundation, each of which acting with different mechanisms. The proposed approach was evaluated versus field observations from the 1964 Niigata, the 1990 Luzon, and the 1999 Adapazari earthquakes, in addition to an assessment against numerical simulations. It was shown that the methodology is capable of estimating the bearing capacity of liquefiable soils under shallow foundations. The obtained results reveal that decreasing the thickness of the liquefiable layer as well as increasing foundation width leads to a higher bearing capacity. Finally, an easy to use design charts and simple equations have been derived for use in engineering practice.
... Since liquefaction occurs under undrained conditions, permeability of the soil is the one of the most influential parameter here -the liquefaction phenomenon majorly depends on the relationship among loading rate and permeability [14]. Besides, it is a very important fact that silts or silty soils are abundant in zones of poor local soil conditions, which are underlain by soils previously exposed to earthquake induced ground shaking, therefore, significant amount of deformations, soil failure and superstructural damage were observed in previous earthquakes [15][16][17][18][19][20]. Post-liquefaction settlement is another problem, settlements occurring due to dissipation of excess pore water pressure after main shock causes large deformations during reconsolidation, along with a significant loss in shear strength and rigidity [21,22]. ...
This study presents an investigation into liquefaction and post-liquefaction behavior of a nonplastic silt under cyclic loading. A systematic approach was adopted for assessment of above-mentioned behavior by performing cyclic triaxial tests on saturated specimens in terms of pore water pressure build-up characteristics, effective stress, number of cycles and double amplitude axial strain. The specimens, consolidated under an effective confining pressure of 100 kPa, were prepared at relative densities ranging among 30–80%. The results revealed that the axial strains of specimens of lower relative densities were increased at higher CSR levels. For prediction of pre- and post-liquefaction behavior, a family of curves for establishing relationships among factor of safety to liquefaction, post-liquefaction volumetric strain and relative density were established. These curves, along with the calculation of post-liquefaction volumetric strain, may be useful in estimation of settlements of silt after being subjected to cyclic loading.
... Site effect studies following the 1999 Marmara earthquake have mainly concentrated east of Adapazarı (Bakır et al. 2002;Komazawa et al. 2002;Sancio et al. 2002;Ansal et al. 2004;Beyen & Erdik 2004;Bray et al. 2004) and western part of Istanbul (Cranswick et al. 2000;Özel et al. 2002Tezcan et al. 2002;Ergin et al. 2004;Sorensen et al. 2006;Parolai et al. 2009, Kurtuluş 2011Picozzi et al. 2009;Ansal et al. 2011). The microzonation project of Istanbul Metropolitan Municipality (IMM 2002(IMM , 2003(IMM , 2007 was carried out to investigate the shallow soil structure by means of Vp and Vs 30 velocity distribution, drilling, resistivity and so on in western Istanbul (the study went on only the areas between Avcılar and Haliç). ...
It has been shown that during the 17 August 1999 Izmit earthquake local site effects affected ground motion in distant areas such as the damage observed in Avcılar, west of İstanbul. Despite efforts to study soil conditions in Istanbul in recent years, site effect problems in the deeper soil are not completely defined. Besides this, the main problems expected in the city of İstanbul will be the result of amplification of ground motion due to an earthquake. To understand these effects, studies were carried out which showed either limited measurements or provided data for shallow depth by obtaining only the depth of engineering bedrock or the average shear wave velocity down to 30 m depth (Vs30).
In this study we determine seismological bedrock depth and the soil properties using microtremor array measurements on 25 sites on the European side of Istanbul. The results are evaluated and compared with previous studies using a joint inversion of the Rayleigh wave dispersion curve and horizontal/to vertical (H/V) spectrum to describe the deeper subsurface and prove the reliability of the resulting models. It has been also proved that the joint inversion approach is more sensitive in predicting the bedrock depth when compared with the Rayleigh wave analysis results.
2-D and 3-D structures of the underground are constructed to define the bedrock depth of the study area. In the south of the study area (sites: Büyükçekmece, Avcılar, Esenyurt, Florya, Yeşilköy, Zeytinburnu and Yedikule) shear wave velocities of the subsurface materials near to the surface are <300 m/s and the engineering bedrock is reached at 200-400 m. The shear velocity models point to a thick sedimentary cover and sediment thickness of 600 m in the south which decreases to the north to 100 m. 3-D shear wave velocity models reflect evidence of different basin structures in the study area, which are of great importance due to resonance effect as well as focusing effects of the seismic waves on the basin edges, non-linear behaviour and phase transition of seismic waves.
Key Words: Marmara, NAFZ, İstanbul, Site effects, SPAC, Microtremor, Joint inversion of Rayleigh wave dispersion curve and H/V spectrum, 3-D Shear wave velocity structure, Seismological bedrock, Array Size
... The amplification of ground motion by soft soil deposits played a significant role in the damage distribution, for example, in the 1985 Michoacán Earthquake in Mexico City, the Leninakan earthquake in Armenia (1988), or the Loma Pietà earthquake in California (1989). Recent destructive earthquakes (e.g., an earthquake in California in 1994;Kobe, 1995;Izmit, 1999;Taiwan 1999or Colima, 2003 have confirmed that at large epicentre distances, the distribution of damage is also strongly influenced by site effect problems with other soil problems, such as soil liquefaction and soil settlement that is induced by soil liquefaction [Bakır et al. 2002, Komazawa et al. 2002, Özel et al. 2004, Sancio et al. 2002, Tezcan et al. 2002Bray 2004;Beyen and Erdik 2004;Ansal et al. 2004;Sorensen et al. 2006]. ...
Urban transformation in Turkey occurs in a rapid and disorganized form that causes major problems during disasters. In countries such as Turkey, where natural disasters occur frequently, sensitivity to urban planning and natural disasters should be addressed using geophysical, geotechnical and microzonation maps.
This paper aims to show the results of seismic microzonation maps that define soil problems and interpret results with appropriate approaches that use multiple parameters, including shear wave velocity soil amplification, soil fundamental frequency and electric resistivity, from a series of geophysical measurements made on a 540-ha area in the city of Bursa, NW Turkey. In urban transformation studies, non-destructive techniques generated by geophysical applications have been considered to be a first step when monitoring the ground surface in archaeological buildings and old residential areas, such as in Bursa, which was once the capital city of the Ottoman Empire. In this study, a flowchart in five basic steps, developed for the organization of a successful urban transformation study, based on microzonation. These steps include 1- general properties of the study area (regional tectonic and seismotectonic), 2- characteristics of earthquakes and soils, 3- site characterization and type of soil problems, 4- data availability and quality, and 5- evaluation of results and decision-making. The results are re-organized to achieve systematic criteria for urban transformation. Remarkably, no standard criteria currently exist. This study illustrates that geophysical data provide a useful basis for land-use planning in cities at risk of earthquakes.
... Cyclic softening of the foundation soil has also led to partial bearing failure or limited punching of foundations into the ground. Prime examples of extensive liquefactioninduced damage to buildings on shallow foundations are presented by the 1999 Kocaeli, Turkey earthquake (Sancio et al. 2002) and the 2010 Maule, Chile earthquake (Bertalot et al. 2013). ...
Historical and recent earthquakes often remind the need for taking precautions against earthquake-induced liquefaction damage that structures on shallow foundations can suffer. Air injection technique has the potential to improve the soil supporting new and existing structures. There is, however, little research on its application and performance beneath existing shallow foundations. The aim of this research was to provide a comprehensive view of the air injection technique by conducting well-controlled dynamic centrifuge and 1-g shaking table tests, along with static soil column experiments in the laboratory. Detailed analysis of the test results highlighted that air injection was an effective way of minimising the soil-softening and loss of shear stiffness associated with earthquake-induced liquefaction. A decreasing trend in the magnitude of excess pore pressures and foundation settlements was observed with decreasing degree of saturation. Air injection technique was also found to perform better under increased confining stresses. Injecting air in a controlled manner (e.g. applying low air injection rate and pressure) was shown to be crucial for the safety of foundations. A wider and more uniformly desaturated zone was achieved with increasing air injection pressure, but which concurrently increased the settlements that shallow foundations experienced. It was also found that most of the air could remain entrapped in partially saturated soil under different simulated field conditions for a long period of time, which indicated the long-term reliability of the mitigation accomplished. Particle image velocimetry was utilised to identify deformation mechanisms that develop underneath and in the ground surrounding shallow foundations. It was shown that foundations resting on saturated soil settled excessively. Foundation settlements were predominantly driven by deviatoric strains, and a bearing capacity failure mechanism did form. When air was injected into saturated soil, air reduced the build-up of excess pore pressures as it contracted during dynamic loading but increased soil compressibility. Deviatoric strain-induced deformations significantly reduced, which resulted in much smaller settlements. The observed settlements were principally caused by volumetric strains that arose from increased soil compressibility. Given the depth of liquefaction reduced significantly for air-injected partially saturated soil, a complete bearing capacity failure mechanism could not occur. The lower the degree of saturation, the shallower and more localised the deformations were observed.
... There are a number of experiments and field data analysis that have studied settlement conditions [e.g [4][5][6][7][8].]. Casagrande [9] was the first who represented the tendency of loose saturated sand to reduce the volume under cyclic loadings. ...
Geotechnical design codes have been shifted from classical limit equilibrium analysis toward the performance-based procedures. In foundation design, settlement is the most representative parameter for its performance. Settlement of shallow foundations subjected to earthquake loading and its consequences is one of the most outstanding issues which should be considered in designing different structures. In this study, settlement of shallow footing on two-layered subsoil strata under earthquake loading is of concern. The numerical study presented in this research by means of a 3D dynamic fully coupled u-p analysis, addresses the effect of different parameters on shallow foundation settlement rested on two-layered soil. Results show that the presence of dense layer can mitigate the settlement up to 50% in comparison to uniform liquefiable layer. Putting the results of all the analyzes together, an equation was proposed in order to estimate shallow foundation settlement on two-layered subsoil.
Low-density saturated soils tend to decrease in volume when dynamic or static loads are applied. It causes the phenomenon of liquefaction in the soil. The main criterion in estimating liquefaction potential is based on the comparison of steady state non-drained strength and shear stress of the stimulus. In these methods, first, based on an earthquake, a specific design and according to the seismic characteristics of the bedrock and the effect of soil conditions on the earthquake, the average shear stress induced by the earthquake at any depth is determined. In this study, in order to investigate the possibility of liquefaction on a liquefiable soil, first field and laboratory studies were performed, then using the latest modified relationships by Idriss and Boulanger, liquefaction risk was estimated and then by Seed and Idriss criteria have been compared.
The earthquake in Sivrice, the district of Elazığ, took place at 20:55 (with local time, GMT+3) on January 24, 2020, with a magnitude of 6.8 in Turkey. This earthquake was felt in some districts and villages of Malatya as well as Elazig province and caused loss of life and property. After the earthquake, on-site investigations were carried out in the earthquake area. It was observed that liquefaction and lateral spreading occurred in alluvium soil deposits that are considered to be close to surface at lake shores and reservoir of the dams, but no soil-induced damage was observed in the city center. It is understood that extensive geotechnical investigations should be carried out in order to prevent damage to the structures due to soil problems in case of larger earthquakes. The common observed structural damages in the reinforced concrete (RC) buildings occurred due to short column effect, large and heavy overhangs, beam discontinuity, workmanship defects, and lack of control. Along with the masonry buildings in Elazig center and villages, damages that occurred in traditional stone masonry houses at the villages of Elazığ and Malatya had been examined, and causes had been investigated. Different levels of damage occurred widely in masonry minarets that did not meet adequate engineering service. In this study, geotechnical and structural damages have been investigated, and suggestions have been presented for the preparation of the region in question on active faults for possible earthquakes.
p>Ground improvement has become one of the most effective tools of geotechnical engineering, being adopted for an always larger variety of civil engineering applications. To reduce the role of subjective choices of operators, the use of different techniques tends to be codified by specific guidelines. In the European Union there is an ongoing effort to standardize execution and design within codes continuously reviewed by designated committees. A widespread and systematic standardisation on the ground improvement as a mean to mitigate the effects of liquefaction on buildings and infrastructures is missing. The paper presents and overview of traditional and new ground improvement technologies suitable for this application. The methods are firstly classified by considering their effects on the ground (e.g. densification, stabilization, drainage, desaturation, etc.). Design principles are then outlined for new or pre-existing buildings and infrastructures, considering the ongoing review process of the design Eurocodes.</p
To investigate the distributing disciplinarian of ground motion parameters on the earth fissure site during strong earthquakes, a series of shaking table tests were designed and conducted based on 1:15 scaled models. Test results showed significant differences in the ground motion parameters (including ground motion intensity indices, spectrum characteristics and strong motion duration) between the hanging-wall and footwall caused by the earth fissure. Acceleration response, displacement response and Arias Intensity response on both sides of earth fissure indicated that the earth fissure site on the hanging-wall was destroyed more seriously. The distributing disciplinarian of amplification factors showed clear “hanging-wall and footwall effects”, which were more remarkable nearby the fissure zones. The low-frequency component of the seismic wave was richer after selectively filtering in the soil medium. By comparing the predominant period and mean period of the hanging-wall and footwall, it was found that vibration frequency on the hanging-wall was greater than that on the footwall. Minimum values of strong motion duration were recorded on the hanging-wall close to the fissure and increased from the fissure to both sides.
A series of shaking table tests on a scaled model were conducted to investigate the effect of steel braces on reinforced concrete frame structure across earth fissure under earthquake. In the test, a 1/15 scaled model structure taking into account soil–structure interaction was designed on the basis of similarity theorem. Seismic response data, including acceleration responses, displacement responses, shear force distributions, and strain amplitudes of column reinforcement were obtained and analyzed by comparing the results of unbraced and braced structure. Results show that with the peak ground acceleration of input motions increased, maximum of inter‐story drifts, shear forces, and strain amplitudes increased, whereas the acceleration amplification factors decreased. Steel braces could obviously reduce the seismic response of the structure, indicating that this retrofit method is an effective control measure for structures across the earth fissure under earthquake. These results are significant for studying the effect of earth fissure on seismic responses of structures.
A series of cyclic and monotonic direct simple shear experiments was conducted on mixtures of non-plastic silt and bentonite, prepared with two different pore fluids: fresh deionized water, and saline-water with a 35 g/L concentration of NaCl (consistent with sea water). The clay fractions were adjusted to achieve a plasticity index of PI=9, with the fresh-water blend requiring 5% bentonite and the saline water blend requiring 10% bentonite. Though both blends have the same plasticity index, differences in cyclic behavior were observed. The relationship of cyclic stress ratio versus number of cycles and the ratio of cyclic stress to monotonic undrained strength was higher for the saline water blend than for the fresh water blend. Results indicate that plasticity index alone is an insufficient indicator of cyclic strength. Corrections for pore fluid chemistry (and by extension, depositional environment) may be necessary, in addition to possibly other factors, for procedures to assess the potential for liquefaction susceptibility and cyclic softening.
Field observations are particularly important in geotechnical earthquake engineering because it is difficult to replicate in the laboratory the characteristics and response of soil deposits built by nature over thousands of years. Much of the data generated by an earthquake is perishable, so it is critical that it is collected soon after the event occurs. Detailed surveys of damaged and undamaged areas provide the data for the well-documented case histories that drive the development of many of the design procedures used by geotechnical earthquake engineers. Thus, documenting the key lessons learned from major earthquakes contributes significantly to advancing research and practice in geotechnical earthquake engineering. This is one of the primary objectives of the Geotechnical Extreme Events Reconnaissance (GEER) Association. Recent GEER post-earthquake reconnaissance efforts and findings are described. The use of advanced reconnaissance techniques is highlighted, as well as specific technical findings from several earthquakes: 2010 Haiti, 2010 Maule, 2010–2011 Canterbury sequence, 2016 Ecuador, 2016 Central Italy, 2016 Kaikoura, and 2017 Puebla-Mexico City.
The liquefaction potential index (LPI) has been extensively applied to ground liquefaction hazard assessments. In this paper, the Robertson’s unified cone penetration test (CPT) based method was applied to determine the LPIs for case histories in two well-documented investigation areas: Adapazari in Turkey and Yuanlin City in Taiwan. A statistical method was applied to find LPI threshold values for low, medium, and high ground liquefaction potential at LPIs of 5.6, 12.5, and 21.7, respectively. According to an analysis of the various risk levels by applying Bayes’ theorem of conditional probability, the probabilities of liquefaction are 0, 32.3, 85.2, and 100% at the low, medium, high, and extremely high ground liquefaction risk level, respectively.
Definition and DescriptionEvaluation of Liquefaction ResistanceLiquefaction Analysis – Worked ExampleSPT Correlation for Assessing LiquefactionInfluence of Fines ContentEvaluation of Liquefaction Potential of Clay (cohesive) SoilConstruction of Foundations of Structures in the Earthquake Zones Susceptible to LiquefactionReferences
A technique is developed for compiling liquefaction hazard maps by mapping a parameter termed liquefaction severity index (LSI). LSI, a measure of ground failure displacement, is based on the displacement of lateral spreads on gently-sloping late Holocene fluvial deposits such as floodplains and deltas. By selecting a specific geologic environment, LSI is normalized with respect to site conditions. LSIs are evaluated for several earthquakes in the western United States, and an equation is developed between LSI, earthquake magnitude, and distance from the seismic energy source. This equation and a model of seismic energy sources is used with a published seismic risk algorithm to compile probabilistic LSI maps for southern California. The maps show contours of LSI with 90% probability of nonexceedance in periods of 10, 50, and 250 years. LSI maps are useful for determining the relative liquefaction hazard and provide an index of possible maximum ground displacement.
Following disastrous earthquakes in Alaska and in Niigata, Japan in 1964, Professors H. B. Seed and I. M. Idriss developed and published a methodology termed the "simplified procedure" for evaluating liquefaction resistance of soils. This procedure has become a standard of practice throughout North America and much of the world. The methodology which is largely empirical, has evolved over years, primarily through summary papers by H. B. Seed and his colleagues. No general review or update of the procedure has occurred, however, since 1985, the time of the last major paper by Professor Seed and a report from a National Research Council workshop on liquefaction of soils. In 1996 a workshop sponsored by the National Center for Earthquake Engineering Research (NCEER) was convened by Professors T. L. Youd and I. M. Idriss with 20 experts to review developments over the previous 10 years. The purpose was to gain consensus on updates and augmentations to the simplified procedure. The following topics were reviewed and recommendations developed: (1) criteria based on standard penetration tests; (2) criteria based on cone penetration tests; (3) criteria based on shear-wave velocity measurements; (4) use of the Becker penetration test for gravelly soil; (4) magnitude scaling factors; (5) correction factors for overburden pressures and sloping ground; and (6) input values for earthquake magnitude and peak acceleration. Probabilistic and seismic energy analyses were reviewed but no recommendations were formulated.
Shaking table tests were conducted on models of rigid structures placed on saturated sand in order to study the pore pressure development in the sand near the structure and to study the factors which influenced the settlement of the structure. The settlement records of reinforced concrete buildings during the Niigata earthquake of 1964 were reviewed for comparison with the model test results.
The studies showed: (1) The excess pore pressure developed below the center of the model structure was smaller than that away from the structure. (2) The ratio of the excess pore pressure to the initial effective stress below the center of the model structure decreased as the structure became heavier. (3) For both the model and the prototype the settlement of the structure decreased as the width of the structure increased for a given depth of liquefaction. (4) A pair of rigid walls embedded on both sides of the model structure had a considerable effect on reducing the excess pore pressure below the structure and a marked effect on reducing the settlement of the structure.
Earthquake Protection: Past Failure and Present OpportunityEarthquake DisastersEarthquakesEarthquake ProtectionOrganisation of the BookFurther Reading
The purpose of this paper is to clarify the meaning of the values of standard penetration resistance (SPT) used in correlations of field observations of soil liquefaction with values of N//1 measured in SPT tests. The field data are reinterpreted and plotted in terms of a newly recommended standard, (N//1)//6//0, determined in SPT tests where the driving energy in the drill rods is 60% of the theoretical free-fall energy. Energies associated with different methods of performing SPT tests in different countries and with different equipment are summarized and can readily be used to convert any measured N-value to the standard (N//1)//6//0 value. Liquefaction resistance curves for sands with different (N//1)//6//0 values and with different fines contents are proposed.
Eight centrifuge model experiments were conducted to investigate the mechanism of liquefaction-induced settlement of a shallow foundation, as well as the effectiveness of sand densification by vibrocompaction under the footing. Two series of model tests were performed with a surface circular footing placed on a medium-dense saturated sand layer overlying an impervious rigid base. The base of each model was excited in flight by horizontal shaking simulating an earthquake; in all cases this shaking liquefied the sand in the free field. The first series of tests (series C) focused on the effect of the depth of soil compacted under the foundation on the footing acceleration and settlement. It was found that, as the compaction depth increased and approached the total thickness of the soil deposit, the footing acceleration during shaking increased and its settlement decreased. In the second series of tests (series G), the soil was not densified; this series focused on the effect of soil permeability on pore pressure buildup and footing settlement. It was found that, as the soil becomes more impervious, significant negative excess pore pressures develop under the footing during shaking, and the contribution of postshaking foundation settlement increases, while the total foundation settlement does not change very much. The paper includes a discussion of building settlements observed after two earthquakes in liquefied areas of Niigata, Japan in 1964, and Dagupan, Philippines in 1990, as well as comparisons between these field observations and the centrifuge results.
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