Fujun Niu

• PhD
• Principal Investigator at Chinese Academy of Sciences

Thermokarst lakes are widely distributed in the Qinghai–Tibet Plateau (QTP) and continuously disturb the permafrost structure. Investigating the permafrost and sublake talik structures is crucial to assessing and predicting the fate of the ecosystem and engineering under climate warming. Until recently, measurements of the permafrost distribution a...

In the context of global warming, landscapes with ice-rich permafrost, such as the Qinghai–Tibet Plateau (QTP), are highly vulnerable. The expansion of thermokarst lakes erodes the surrounding land, leading to collapses of various scales and posing a threat to nearby infrastructure and the environment. Assessing the susceptibility of thermokarst la...

Embankment–bridge transition sections (EBTSs) suffer from diverse engineering diseases that have escalated into one of the most severe issues along the Qinghai‐Tibet Railway (QTR). Nevertheless, the causes and mechanisms of engineering diseases in EBTSs remain limited. This study employed a methodological approach to conduct field surveys in the Tu...

To achieve environmental and economic goals in ground improvement, a one-part geopolymer (OPG), synthesized from binary precursors (fly ash [FA] and granulated blast furnace slag [GGBFS]) and a solid activator (solid sodium silicate [NS]), was used to replace ordinary Portland cement (OPC) for stabilizing high-water-content soft clay. The effects o...

The aggregate breakup of structured soft clay has an important influence on the properties of the soil. In this paper, the aggregate breakup of structured soft clay under one-dimensional compression is investigated based on FESEM images, and the relative breakage Br is used to assess the degree of aggregate breakup, and the results show that: The s...

Thermokarst lakes are shallow bodies of freshwater that develop in permafrost regions, and they are an essential focus of international permafrost research. However, research regarding the mechanisms driving temperature fluctuations in thermokarst lakes and the factors that influence these changes is limited. We aimed to analyze seasonal variations...

Research in geocryology is currently principally concerned with the effects of climate change on permafrost terrain. The motivations for most of the research are (1) quantification of the anticipated net emissions of CO 2 and CH 4 from warming and thaw of near‐surface permafrost and (2) mitigation of effects on infrastructure of such warming and th...

Highways and their surrounding areas in mountainous and plateau regions are particularly susceptible to environmental changes, which can significantly impact their safety. In the context of global warming, the magnitude of environmental changes around highways has been further amplified. These environmental disturbances pose substantial risks to hi...

Ubiquitous and complex avalanche–substrate interactions during rock avalanche emplacement have attracted widespread attention in recent years and are regarded as vital processes influencing mobility and damage potential through rapid changes in avalanche mechanical properties. However, the fundamental interaction mechanisms of avalanche mass on sub...

The tensile strength is an important parameter in engineering. Many engineering-related problems in buildings as well as the damage caused to them during natural disasters occur owing to a lack of tensile strength. The unconfined penetration (UP) test is an indirect method to measure the tensile strength of soil. Analyses of the mechanism of the UP...

In recent years, urban road collapse incidents have been occurring with increasing frequency, particularly in populous cities. To mitigate road collapses, geophysical prospecting plays a crucial role in urban road inspections. Ground Penetrating Radar (GPR), a non-destructive technology, is extensively employed for detecting urban road damage, with...

Machine learning methods have a wide range of applications, including predicting soil compression coefficients for offshore wind power projects. This study compared three machine learning methods (Extreme Gradient Boosting, Random Forest, and Bayes) with traditional empirical formulations. Results revealed distinct spatial distribution characterist...

Freeze–thaw (FT) erosion intensity may exhibit a future increasing trend with climate warming, humidification, and permafrost degradation in the Qinghai–Tibet Plateau (QTP). The present study provides a reference for the prevention and control of FT erosion in the QTP, as well as for the protection and restoration of the regional ecological environ...

Climate warming and anthropogenic disturbances result in permafrost degradation in cold regions, including in the Qilian Mountains. These changes lead to extensive hillslope thermokarst (HT) formation, such as retrogressive thaw slumps, active-layer detachment slides, and thermal erosion gullies. These in turn cause, e.g., degradation of local vege...

The degree of water saturation significantly affects the rate of rock deterioration caused by freeze–thaw weathering, which may trigger serious geological engineering hazards. This study aimed to explore the impacts of water saturation on freeze–thaw-induced deterioration of sandstone, and to improve our understanding of this damage mechanism. Sand...

The effect of K0 consolidation-induced initial stress anisotropy on the mechanical behavior of soft soil and the evolution patterns of structural damage of soil during triaxial loading were investigated. A series of K0 consolidated and isotropically consolidated undrained triaxial compression tests were carried out. Microstructural information of s...

Climate warming and anthropogenic disturbances result in permafrost degradation in cold regions, including in the Qilian Mountains. These changes lead to extensive hillslope thermokarst (HT) formation, such as retrogressive thaw slumps, active-layer detachment slides, and thermal erosion gullies. These in turn cause, e.g., degradation of local vege...

Changes of the lakes on high-altitude regions of the Tibet Plateau (TP) influence the state of the surrounding permafrost. Due to the climate warming and wetting trend, extreme events including lake outburst has occurred more frequent. In 2011, an outburst event occurred on the Zonag Lake and this event changed the water distribution in the basin,...

The outburst of Zonag Lake in 2011 triggered a series of floods in the continuous permafrost region of the hinterland of the Qinghai-Tibet Plateau. This re-distributed the surface water in the basin and caused rapid expansion of the tail lake (Salt Lake). To avoid potential overflow of the expanding Salt Lake, a channel was excavated to drain the l...

Permafrost areas are sensitive to climate change and have a significant impact on energy and water cycles. Ground ice is a crucial component on the Qinghai–Tibetan Plateau (QTP). Understanding the environmental characteristics of ground ice is vital for accurately modeling its distribution and evolution. In this study, we analyzed 15 environmental...

In cold mountainous regions of China, the construction of highways is challenging, owing to frost damage of weak subgrade soils and the difficulties posed from dealing with waste materials derived from tunnel excavation. In order to address these issues, Wu et al. proposed a new approach of using coarse gravel reclaimed from tunnel excavation as an...

In the mountainous permafrost area, most thaw slumps are distributed in north or northeast-facing shady slope areas. It is commonly known that there is a heterogeneity in permafrost between different slope aspects, but there has been a lack of detailed measured data to quantitatively evaluate their relationships, and in-depth understandings on how...

The Qinghai-Tibet Railway has been operating safely for 16 years in the permafrost zone and the railroad subgrade is generally stable by adopting the cooling roadbed techniques. However, settlement caused by the degradation of subgrade permafrost in the embankment-bridge transition sections (EBTS) is one of the most representative and severe distre...

Retrogressive thaw slumps (RTSs), which frequently occur in permafrost regions of the Qinghai-Tibet Plateau (QTP), China, can cause significant damage to the local surface, resulting in material losses and posing a threat to infrastructure and ecosystems in the region. However, quantitative assessment of ground ice ablation and hydrological ecosyst...

The mechanical behaviors of granular materials are dominated by internal structure, which are related to fabric evolution during loading. This study investigated the fabric evolution of granular materials with different densities and stress paths under true triaxial conditions. A series of discrete element numerical simulations with different inter...

Strength anisotropy is an important feature closely related to soil microstructure characteristics. A new anisotropic failure criterion, extended from the Ogawa failure criterion, was developed to describe the strength anisotropy of cross-anisotropic soils. Nonlinearization of the failure curves of the Ogawa failure criterion was introduced to acco...

In order to research the special embankment (thermosyphon embankment) damages and the distribution of permafrost under the Qinghai–Tibet Highway (QTH) embankment. The section K2952–K2953, which is a typical representative of the QTH, was chosen for the detection and research of the permafrost and embankment damages in order to determine the sources...

This work aims to investigate the influence of structural damage to natural soft clay on its mechanical behavior. K0 consolidated triaxial tests with loading and unloading stress paths were conducted, and field emission scanning electron microscopy (FESEM) and mercury intrusion porosimetry (MIP) were utilized for microstructural investigation. Macr...

The degradation of ice-rich permafrost can form thermokarst landforms such as thermokarst lakes. There are a large number of thermokarst lakes distributed in the ice-rich permafrost region of the Qinghai–Tibet Plateau. However, the effect of the spatial distribution of thermokarst lakes on permafrost degradation at a regional-scale in the Qinghai–T...

With the rapid development of human lunar exploration projects, the lunar base establishment and resource utilization are on the way, and hence it is urgent and significant to reasonably predict engineering properties of the lunar regolith, which remains to be unclear due to limited lunar samples currently accessible for geotechnical tests. In this...

With global climate change and increasingly extreme weather conditions, the water quality of the Lijiang River Basin (LRB) is facing huge threats. At present, there is still a lack of systematic research on water quality indicators and the influence of indirect factors such as meteorological factors on it in the LRB. Therefore, this study is based...

Solifluction terraces are a topographic and sedimentary signature for understanding the mechanism of solifluction occurrence and the past climate (e.g., paleoclimate), and have also impacts on hillslope stability. Traditional field surveys and aerial remote sensing have been primarily employed to map solifluction terraces, but they have challenges...

The formation and development of thermokarst lakes is a key factor causing permafrost degradation, in which the vertical hydraulic conductivity (Kv) of lakebed sediments plays an important role as it affects the water and heat transfer between thermokarst lakes and permafrost. However, the spatial variability of Kv of lakebed sediments in the Qingh...

Cold regional tunnels have been encountering numerous frost damages as a result of dynamic changes in hydrothermal conditions of tunnel structural layers. The climate change is recognized as a major contributor for the problems. In this study, the hydrothermal conditions of a high-speed railway tunnel are evaluated under different climate scenarios...

Due to the increasing air temperatures, retrogressive thaw slumps (RTSs) have become more common on the Qinghai–Tibet Plateau (QTP), but their inventory, frequency, and initiation have not been fully investigated. In satellite imagery for the period 2018–2020, 2669 active RTSs were identified in permafrost regions of the QTP. Most of the RTSs occur...

Permafrost has been warming and thawing globally, with subsequent effects on the climate, hydrology, and the ecosystem. However, the permafrost thermal state variation in the northern lower limit of the permafrost zone (Xidatan) on the Qinghai–Tibet Plateau (QTP) is unclear. This study attempts to explore the changes and variability in this permafr...

Frozen soil is a kind of composite geotechnical material with significant creep properties. To develop a creep constitutive model that can consider the composite properties and internal microcosmic damage mechanism of frozen soil, it is first conceptualized as a binary medium material containing both bonded elements and frictional elements, and the...

Ice-rich permafrost in the Qinghai–Tibet Plateau (QTP), China, is becoming susceptible to thermokarst landforms, and the most dramatic among these terrain-altering landforms is retrogressive thaw slump (RTS). Concurrently, RTS development can in turn affect the eco-environment, and especially soil erosion and carbon emission, during their evolution...

The slope aspect effect is widely distributed on the Qinghai-Tibet Plateau and has an important impact on the permafrost environment. The differences in surface heat exchange characteristics of different slope aspects in the permafrost region of Gu Mountain in the Beiluhe Basin were compared and analyzed based on observations of the south slope (su...

Thermokarst lakes are an important ecosystem component in permafrost terrains; therefore, quantifying changes in these lakes is important for evaluating the water balance and carbon budget on the Qinghai-Tibet Plateau (QTP). In this study, we utilized high spatial resolution aerial and satellite images from 1969, 2010, and 2019 to quantify changes...

XPS board as a good insulator is extensively used in construction and engineering to reduce heat loss. Unfortunately, the performance degradation of XPS board caused by freeze- thaw cycles (FTCs) was poorly studied. In view of this, a series of experiments were carried out in the laboratory. The compressive strength, thermal conductivity and volume...

Cast-in-place pile foundations are widely used in permafrost regions to support buildings. The stability of cast-in-place pile foundations is highly sensitive to permafrost thermal regime changes. Permafrost degradation caused by climate change is increasing the disaster risk of cast-in-place pile foundations. However, proactive cooling methods for...

In this study, a series of three-dimensional small-strain analyses are carried out to explore the combined capacity of bucket foundations in soft-over-stiff clay under general loading. It aims to provide a supplement to existing design codes. Numerical models are generated and validated with existing data in open literature, where good agreements a...

It is proposed to build a high-speed railway through the China‒Mongolia‒Russia Economic Corridor (CMREC) which runs from Beijing to Moscow via Mongolia. However, the frozen ground in this corridor has great impacts on the infrastructure stability, especially under the background of climate warming and permafrost degradation. Based on the Bayesian N...

Highways are the main components of modern transportation hubs, where lots of pavement anomalies have been still occurring with the increasing of the traffic volume and overloading, especially for the coastal developed areas. Rapid nondestructive detection is a necessary means to ensure uninterrupted highway traffic in the road operation period. In...

Permafrost degradation and the development of thermokarst lakes are important factors driving the variability of regional hydrologic processes. Hydrogeochemical and isotopic analyses are important methods for investigating the hydrologic processes of thermokarst lakes. This study focused on comparing the chemical and hydrogeochemical characteristic...

Permafrost has been warming and thawing at a global scale with subsequent effects on the climate, hydrological, ecosystem and engineering system. However, the variation of permafrost thermal state in the northern lower limit of the permafrost zone (Xidatan) on the Qinghai–Tibetan Plateau (QTP) is unclear. To evaluate and project the permafrost chan...

As the climate and the external environment have changed, the environmental factors of the Lijiang River Basin (LRB) have changed, posing new threats to the environmental quality, ecosystem balance, and management and protection of the water environment of the Lijiang River. Water quality indicators and environmental factors vary spatially along th...

Permafrost in Northeastern China has significantly degraded due to global warming, deforestation and urbanization in the last few decades. The frost heave and thaw subsidence induced by freeze-thaw cycles of deep seasonal frozen ground have caused serious damage to infrastructures. The Shiwei-Labudalin (Shi-La) Highway is an important infrastructur...

To establish a strength criterion that can consider the composite properties and internal non-homogeneity of frozen soil, a load sharing model is first defined based on homogenization theory and the binary-medium structure model, and then the strength functions of frozen soil on the p-q plane and the π plane are established, respectively. Finally,...

The purpose of this research is to explore the feasibility of using calcium carbide residue (CCR), a by-product from acetylene gas production, as a solid alkaline activator on the strength development in CCR-Portland cement-stabilized dredged sludge (CPDS). The effects of cement content, CCR content and curing time on the strength development of CP...

As an important indicator of permafrost degradation, surface deformation is often used to monitor the thawing and freezing process in the permafrost active layer. However, due to the large area of the continuous permafrost of the Qinghai–Tibet Plateau (QTP) and the large amount of data processed by conventional time-series InSAR, previous studies h...