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Soil slopes located in more rainfall region have been damaged significantly in the previous earthquakes due to the earthquake-induced excess pore water pressure (EPWP), which is among primary factors causing slope failure. For the purpose of evaluating seismic behaviors of an unsaturated soil slope at various groundwater levels, we established a simple approach for calculating earthquake-induced EPWP, which is importable to the numerical simulation software through the custom interface. Based on this, we investigate the seismic performance of the unsaturated soil slope. It is observed that the seismic performance of the slope has much difference at various groundwater levels; the slope deformation at a high groundwater level increases greatly while the groundwater reduced the vibration of the slope. Also, it was found that the slope shows different failure processes with the groundwater influence: the failure of slope with high groundwater is mainly the flow slide and tensile crack around the slope toe while the slope presents the collapse and slip failure without the groundwater influence. Moreover, by strict similarity law formula derivation, the shaking table test of two slope models, one without groundwater and one with groundwater, was performed, and the test results show that our calculation results are accurate and reasonable, and our establishment calculation method of EPWP is practical and convenient.

The detachment of large parts of low-angle mountain glaciers resulting in massive ice–rock avalanches have so far been believed to be a unique type of event, made known to the global scientific community first for the 2002 Kolka Glacier detachment, Caucasus Mountains, and then for the 2016 collapses of two glaciers in the Aru range, Tibet. Since 2016, several so-far unrecognized low-angle glacier detachments have been recognized and described, and new ones have occurred. In the current contribution, we compile, compare, and discuss 20 actual or suspected large-volume detachments of low-angle mountain glaciers at 10 different sites in the Caucasus, the Pamirs, Tibet, Altai, the North American Cordillera, and the Southern Andes. Many of the detachments reached volumes in the order of 10–100 million m3. The similarities and differences between the presented cases indicate that glacier detachments often involve a coincidental combination of factors related to the lowering of basal friction, high or increasing driving stresses, concentration of shear stress, or low resistance to exceed stability thresholds. Particularly soft glacier beds seem to be a common condition among the observed events as they offer smooth contact areas between the glacier and the underlying substrate and are prone to till-strength weakening and eventually basal failure under high pore-water pressure. Partially or fully thawed glacier bed conditions and the presence of liquid water could thus play an important role in the detachments. Surface slopes of the detached glaciers range between around 10∘ and 20∘. This may be low enough to enable the development of thick and thus large-volume glaciers while also being steep enough to allow critical driving stresses to build up. We construct a simple slab model to estimate ranges of glacier slope and width above which a glacier may be able to detach when extensively losing basal resistance. From this model we estimate that all the detachments described in this study occurred due to a basal shear stress reduction of more than 50 %. Most of the ice–rock avalanches resulting from the detachments in this study have a particularly low angle of reach, down to around 5∘, likely due to their high ice content and connected liquefaction potential, the availability of soft basal slurries, and large amounts of basal water, as well as the smooth topographic setting typical for glacial valleys. Low-angle glacier detachments combine elements and likely also physical processes of glacier surges and ice break-offs from steep glaciers. The surge-like temporal evolution ahead of several detachments and their geographic proximity to other surge-type glaciers indicate the glacier detachments investigated can be interpreted as endmembers of the continuum of surge-like glacier instabilities. Though rare, glacier detachments appear to be more frequent than commonly thought and disclose, despite local differences in conditions and precursory evolutions, the fundamental and critical potential of low-angle soft glacier beds to fail catastrophically.

The mechanism of land subsidence and soil deformation deals with the dissipation of excess pore water pressure and the compaction of soil skeleton under the effect of natural or man-made factors, which can lead to serious disasters in the process of urbanization. The negative effects of land subsidence include structural and fundamental damages to underground and aboveground infrastructures such as pipelines and buildings, changes in land surface morphology, and creation of earth fissures. Arid and semi-arid countries like Iran are highly prone to land subsidence phenomenon. In these regions, precipitation rate and natural recharges are relatively lower than those of the global average showing the importance of ground waters for agricultural and industrial activities. Land subsidence has already occurred in more than 300 plains in Iran. Semnan Plain is one of the most important areas facing this phenomenon. The purpose of this research was to assess land subsidence susceptibility using random forest machine learning theory. At first, prioritization of conditioning factors was done using random forest method. Results showed that distance from fault, elevation, slope angle, land use, and water table have the greatest impacts on subsidence occurrence. Then land subsidence susceptibility map was prepared in GIS and R environment. The receiver operating characteristic curve was applied to assess the accuracy of random forest algorithm. The area under the curve by value of 0.77 showed that random forest is an acceptable model for land subsidence susceptibility mapping in the study area. The research results can provide a basis for the protection of environment and also promote the sustainable development of economy and society.

The movement of large, slow-moving, deep-seated landslides is regulated principally by changes in pore-water pressure in the slope. In urban areas, drastic reorganization of the surface and subsurface hydrology—for example, associated with roads, housings or storm drainage—may alter the subsurface hydrology and ultimately the slope stability. Yet our understanding of the influence of slope urbanization on the dynamics of landslides remains elusive. Here we combined satellite and (historical) aerial images to quantify how 70 years of hillslope urbanization changed the seasonal, annual and multi-decadal dynamics of a large, slow-moving landslide located in the tropical environment of the city of Bukavu, Democratic Republic of the Congo. Analysis of week-to-week landslide motion over the past 4.5 years reveals that it is closely tied to pore-water pressure changes, pointing to interacting influences from climate, weathering, tectonics and urban development on the landslide dynamics. Over decadal timescales, we find that the sprawl of urbanized areas led to the acceleration of a large section of the landslide, which was probably driven by self-reinforcing feedbacks involving slope movement, rerouting of surface water flows and pipe ruptures. As hillslopes in many tropical cities are being urbanized at an accelerating pace, better understanding how anthropogenic activity influences surface processes will be vital to effective risk planning and mitigation. A large, slow-moving landslide underlying the city of Bukavu in the Democratic Republic of the Congo has accelerated in recent decades due to hydrological modifications related to urbanization, according to an analysis of aerial photographs and remote-sensing data.

Landslides modify the natural landscape and cause fatalities and property damage worldwide. Quantifying landslide dynamics is challenging due to the stochastic nature of the environment. With its large area of ~1 km 2 and perennial motions at ~10–20 mm per day, the Slumgullion landslide in Colorado, USA, represents an ideal natural laboratory to better understand landslide behavior. Here, we use hybrid remote sensing data and methods to recover the four-dimensional surface motions during 2011–2018. We refine the boundaries of an area of ~0.35 km 2 below the crest of the prehistoric landslide. We construct a mechanical framework to quantify the rheology, subsurface channel geometry, mass flow rate, and spatiotemporally dependent pore-water pressure feedback through a joint analysis of displacement and hydrometeorological measurements from ground, air and space. Our study demonstrates the importance of remotely characterizing often inaccessible, dangerous slopes to better understand landslides and other quasi-static mass fluxes in natural and industrial environments, which will ultimately help reduce associated hazards. Landslides are damaging natural hazards and can often lead to unexpected casualties and property damage. Here, the authors conduct geodetic and hydrological data analyses of the Slumgullion landslide, Colorado, and quantify the mass movement to find it fits a power-law flow theory and responds to hydroclimatic variability.

A hard roof implies a large hanging-roof and high-frequency dynamic strata behavior during mining, which poses a great risk to the safety of personnel and equipment. To solve this problem, a water injection softening method was used in the Buertai coal mine in Inner Mongolia, China, which has a hard sandstone roof. Comprehensive experimental tests and numerical simulations were conducted to investigate the water injection softening effect on the hard roof. Uniaxial tests were conducted on water-softened rock specimens to establish the relationship between the water content and mechanical properties, and the permeability was correlated with the pore water pressure and axial stress. A hydromechanical coupling model was developed and implemented in the numerical model by introducing the water-softening elastic modulus and the dynamic porosity model. Numerical modeling of water injection into the hard roof was conducted to characterize the roof behavior and the dynamic flow field under water injection softening. The results showed that (1) the water weakened the strength and elastic modulus of the rock. As the pore water pressure increased, the permeability increased exponentially. However, with increasing axial stress, the permeability decreased exponentially. (2) The Terzaghi effective stress principle and static equilibrium equation were combined to derive the Biot three-dimensional consolidation control equation with the strain tensor and pore water pressure, which can effectively describe the coupling relationship between the pore water flow and the elastic deformation of the elastic body of a porous medium. Expressions for the porosity of the elastic body of the porous medium were determined. Porosity was expressed as a function of the Biot coefficient, volumetric strain, pore water pressure, and bulk modulus, which made the model more comprehensive and reasonable. (3) The pore water pressure, strain, and permeability were higher near the water injection hole. The respective increases in pore water pressure, strain, and permeability were rapid at the beginning and diminished with subsequent water injection.

Excessive rainfall is considered the major landslide triggering mechanism, especially in tropical climate regions. During rainfall, water infiltrates into the subsurface; reducing the matric suction, increasing pore water pressure, and decreasing the shear strength of the soil. The prevailing unfavourable ground and geomorphological conditions can further exacerbate the vulnerability and severity of catastrophic landslides. Hence, it is vital to identify different landslide mechanisms, key drivers for rainfall-induced landslides, and risk assessment methods for adopting appropriate failure mitigation strategies. This study captures a comprehensive review and in-depth analysis based on 200 articles published in literature including authors own case studies to describe the risk management strategies of rain-induced landslides in tropical countries. First, a clear relationship between the rainfall patterns and the landslide events has been proposed through the comprehensive data sets reviewed. Then key influencing factors for landslides in the tropical region have been identified with in-depth discussion from past reported studies. Moreover, landslide risk assessment and management framework are discussed with the key steps involved. The framework provides a better-structured approach to discuss on identifying, analysing, evaluating, and managing risk associated with landslides. The complex geological conditions, lack of rainfall and impact data, and rapid change in land use make quantitative risk assessment challenging in the tropical region. The review finally recommends effective risk mitigation strategies from the authors' experience on past projects and reported literature case studies. The outcomes from the review are beneficial for engineers and authorities for adopting risk mitigation approaches in tropical regions.

During the normal operation of the Huangdeng Hydropower Station's reservoir, many tensile cracks were observed on the surface of the bank slope below the elevation of 1805 m along the highway, causing significant damage to local residents' production and lives. On-site geological investigation, surface and inclinometer displacement monitoring were carried out, and the deformation characteristics of the Cheyiping landslide were analyzed. A controllable intensity rainfall simulator and a reservoir water level variation simulation system were designed in our laboratory. The lower section of the highway along the river in Cheyiping small village was chosen as the prototype, and a centrifuge model test of the reactivation of the Cheyiping ancient landslide induced by rainfall and reservoir water level fluctuations was performed. The characteristics of landslide deformation, pore water pressure, and earth pressure variation under the influence of rainfall and reservoir water level changes are investigated. The thorough analysis revealed that, even if the sliding surface is not deep, the sudden drop in reservoir water level remains the primary controlling factor of slope sliding. Because the permeability of the deposit is low, rainfall has a minor impact on this ancient landslide. The experimental results can be used to guide slope prevention and reservoir management in the Huangdeng Reservoir area.