Landslide Mass Research Articles

Influence of geological and hydrogeological settings in assessing the stability of a landslide slope in the Tutrakan area, Northeastern Bulgaria

The study is focused on the assessment of the stability of the lower part of the right slope of the Danube River. The research area is situated in the town of Tutrakan, Northeastern Bulgaria. The present study investigates the likelihood of activating landslide processes due to construction works on the water supply and sewerage network of the town, as well as the influence of the natural geological and hydrogeological settings of the region. The research area is part of the Danubian Plain. The groundwater level lies between 7 and 26 m below the surface, in the sandy sediments and limestones of the Pliocene that form the semi-confined to unconfined aquifer. They are mainly formed by infiltration of precipitation through the loess layer. The groundwater discharge is carried out naturally and technogenically towards the Danube, through a herringbone system of drains built in the toe of the landslide cirques. The assessment of the slope stability was made for the different hypotheses – natural (momentous – including the existing buildings), constructional (including excavations), primary and specific (including seismic forces) combination of stresses. The different geodynamic models, taking into account the influence of groundwater, the influence of different destabilizing factors and seismic impact, show that the slope, as well as the studied sections of it – the landslide cirques, are in a stabilized state, with safety coefficients (Fs > 1). According to the mechanism of deformation, the landslides are classified as a translational slide, and deep seated according to the depth of the slip zone. They are contemporary and currently active. The study confirms the hypothesis of the origin of the landslide masses in the area, formed as a mixture of loess material and Pliocene clays. The groundwater level is directly related to the current state of the landslide slope stability.

Mechanism Analysis and Process Inversion of the “7.26” Landslide in the West Open-Pit Mine of Fushun, China

Mine landslides are geological disasters with the highest frequency and cause the greatest harm worldwide. This typically causes significant casualties and damage to property. The study of the formation mechanisms and kinematic processes of mine landslides is important for the prevention and control of mine geological disasters and mine production safety. This study examined the “7.26” landslide, which occurred in the West Open-pit Mine of Fushun, China, in 2016, based on detailed investigations, interferometric synthetic aperture radar (InSAR) monitoring, and numerical simulations. The mechanism of landslide formation was explored, its kinematic process was inverted, and its disaster evolution process was summarized. The results indicate that: (1) For the formation mechanism of the “7.26” landslide, in July 2015, the old sliding mass was reactivated and deformed along the dominant joints in the shale. The following year, owing to continuous rainfall during the rainy season, the sliding surface accelerated its connection. Finally, a rainstorm on 25–26 July 2016, triggered slope instability. (2) The process of continued movement after landslide instability was approximately 250 s. It can be divided into the landslide initiation (0–10 s), collision scraping (10–150 s), and accumulation stages (150–250 s). (3) The entire process of landslide disasters includes four stages. During the weak-deformation stage, the maximum deformation of the sliding mass monitored by InSAR was approximately 50 mm. During the strong deformation stage, the tensile cracks at the rear edge of the landslide continued to expand, and shear outlets at the front edge had already formed. During the instability and failure stages, rainstorms trigger slope instability, leading to landslides. During the sliding accumulation stage, the landslide mass transformed into debris flow along the slope surface and accumulated at the bottom of the pit. This study provides a theoretical basis for the subsequent evaluation, treatment, monitoring, and warning of landslides in the Fushun West Open-pit Mine and other deep excavation open-pit mines.

Transition from rock mass creep to progressive failure for rockslide initiation at Mt. Conero (Italy)

The full description of rock mass behaviour involved in slope deformation, through its onset and progression until ultimate failure, is still a challenge in numerical simulations. The slope deformation that involved the coastal sector of Mt. Conero (Italy), leading to the rock avalanche of Portonovo, is an impressive example of a multistage creep evolution involving a jointed rock mass towards general failure. A landslide mass for the last event up to 5 Mm3 has previously been estimated from geomorphological analysis. This volume is not consistent with the size of the scar or the landslide deposit, suggesting a history of failures. Moreover, field evidence of pre-failure strain suggests progressive failure of the slope leading up to failure. In this study, a numerical back-analysis was set up using the finite difference method in a stress–strain approach, which applied an uncoupled solution to simulate the creep process and the progressive failure of the slope, as well as the accumulation of damage. The modelling outputs support the hypothesis that the landslide event was marked by two distinct episodes, each with volumes of approximately 20 Mm3, at 56 and 16 ka, which is consistent with the relative dating constraints. Additionally, a numerical back-analysis of the rock mass viscosity was calibrated and validated on the size of the scar area of the Portonovo landslide and on the morphological and structural evidence. The adopted strain-softening models caused significant differences in strain distribution and slope failure evolution. The proposed modelling demonstrated the importance of the creep process in controlling slope evolution and the reliability of the tested analytical approach for the analysis of progressive brittle rock failure, including the three-stage evolution of time-dependent viscous processes.

Modeling and mapping the environmental impact of debris flow hazard on alluvial fans for sustainable development in Bangga and Poi Villages, Sigi, Central Sulawesi

On September 28, 2018, an Mw 7.5 Palu earthquake triggered massive landslides upstream, followed by 24 debris flood events that spread to 15 villages in Sigi from September 2018 to December 2021. Debris flow and flash floods on alluvial fans inundated lowland communities, causing severe property destruction and structural damage to bridges and roadways and resulting in an estimated 900 damaged houses. Understanding their historical occurrence is essential to sustainable fan development and minimizing their threat to infrastructure and human life due to their severe geohazard potential. Poi and Bangga Villages were affected by the disastrous debris flood in Sigi Regency, Central Sulawesi. This study aimed to create a landslide inventory map, a back-analysis model, and a damage and loss assessment (DaLAs) to evaluate the potential hazard and environmental impacts of debris flow on Sigi’s alluvial fans. The result of landslide mapping showed more than 400 mapped landslides within Bangga Village in various sizes and a massive landslide within Poi Village were digitized. Then, the back-analysis model overpredicted flow direction due to vegetation, infrastructure, and road information not covered by the digital elevation model (DEM). Finally, DaLAs shows the losses caused by damaged buildings were estimated at around 65.7 and 7.4 billion rupiah in Bangga and Poi Villages, respectively.

Enhanced Kinematic Inversion of 3‐D Displacements, Geometry, and Hydraulic Properties of a North‐South Slow‐Moving Landslide in Three Gorges Reservoir

AbstractComplete three‐dimensional (3‐D) movements of slow‐moving landslides are critical to enhancing the understanding of the landslide mechanism. Multi‐source synthetic aperture radar (SAR) observations provide an opportunity to derive 3‐D movements. However, deriving the complete 3‐D movements faces potential challenges of incoherent phases and an ill‐posed inverse problem, which may result in incomplete and inaccurate results, especially for slopes facing north/south. Here, we propose a topography‐constrained strain model, which exploits the spatial relationship of 3‐D deformations between neighboring points as well as the assumption of the surface parallel flow of landslide, to derive complete 3‐D movements. Both synthetic and real datasets over the north‐south Xinpu landslide complex are utilized, to assess if the implemented method can overcome the ill‐posed condition and retrieve the complete 3‐D movement field. With the multi‐source SAR datasets, the performance of various datasets and the potential of NISAR in deriving time series and 3‐D movements are assessed. Based on the derived complete 3‐D movements and long‐term InSAR measurements, the landslide metrics, including elementary parameters of landslide geometry, spatial‐temporal patterns of movement, thickness, and hydraulic diffusivity, are derived to reveal that (a) the thickest landslide mass concentrates in the toe of the landslide, and (b) the effects of precipitation are more significant than those of the water level fluctuation in the Xinpu landslide complex, Three Gorges Reservoir areas.

An Analytical Calculation Method and Mechanical Response Laws of Buried Pipelines Subjected to the Impact of Transverse Landslides

When the buried gathering and transportation pipelines cross the landslide area transversally, the migration of the landslide mass can cause the pipelines to be subjected to lateral thrust, which can seriously affect the safe operation of the buried pipelines. In order to study the mechanical response laws of the buried pipelines under the impact of transverse landslides, based on the elastic-plastic foundation beam theory, the mechanical models of buried pipelines are established for three situations, and the analytical solution of pipeline displacement is obtained by genetic algorithm. The influences of landslide thrust, landslide width, soil resistance coefficient, the pipe outer diameter and wall thickness on pipeline peak displacement and peak stress are also investigated. The results show that under the impact of the transverse landslide, with the increase of landslide thrust, the maximum displacement and maximum tensile stress of pipeline increase exponentially, and the failure risk of pipe increases. Secondly, with the increase of landslide width, the maximum displacement of pipeline increases in the beginning and then decreases to be constant, and the maximum tensile stress decreases sharply to be constant. Thirdly, with the increase of soil resistance coefficient, the maximum displacement and maximum tensile stress of pipeline decrease in a negative power trend, and the pipeline is safer. Fourthly, when the pipe outer diameter increases to a certain value, the maximum displacement and maximum tensile stress of the pipeline change very little, hence, pipe outer diameter can be optimized when designing pipe structure. Fifthly, the smaller the pipe wall thickness is, the greater the maximum tensile stress of the pipe is, therefore, pipe corrosion protection should be paid attention to. Sixthly, when the landslide thrust is large, the landslide width is small, or the pipeline outer diameter is small, the maximum tensile stress of the pipeline is located at the centre of the landslide, otherwise, it is located at 0.56L ~ 0.7L away from the landslide centre. In order to ensure the safe operation of the pipeline, the stress state of these two positions should be focused on. It is concluded that the study can provide the basis for the evaluation of pipeline safety status and has practical significance for ensuring the safe operation of buried pipelines.

GNSS Real-Time Warning Technology for Expansive Soil Landslide—A Case in Ningming Demonstration Area

Efficient monitoring and early warning are the preconditions of realizing expansive soil landslide hazard prevention and control. Previous early warning of expansive soil landslides was evaluated through soil sampling experiments to analyze the stability coefficient. However, the existing methods lack timeliness and ignore the inconsistent deformation characteristics of different parts of the landslide mass. There are still difficulties in the dynamic numerical early warning of landslides at multiple points. Considering that the degradation of expansive soil landslides’ strength is directly reflected by surface displacement, for the Ningming expansive soil demonstration area and based on the GNSS shallow real-time displacement monitoring sequence, a landslide early-warning method based on the GNSS displacement rate combined with the GNSS displacement tangent angle model was proposed, and we thus designed early-warning thresholds for different warning levels. Combined with multi-source data such as soil moisture, soil pressure, and rainfall, the feasibility of accurate early warning of expansive soil landslides based on GNSS real-time surface displacement was verified. The proposed method does not require numerical calculation of internal stress and achieved two successful early warnings of landslides in the test area, which has a certain promotional value.

Landslides Triggered by the 2016 Heavy Rainfall Event in Sanming, Fujian Province: Distribution Pattern Analysis and Spatio-Temporal Susceptibility Assessment

Rainfall-induced landslides pose a significant threat to the lives and property of residents in the southeast mountainous area. From 5 to 10 May 2016, Sanming City in Fujian Province, China, experienced a heavy rainfall event that caused massive landslides, leading to significant loss of life and property. Using high-resolution satellite imagery, we created a detailed inventory of landslides triggered by this event, which totaled 2665 across an area of 3700 km2. The majority of landslides were small-scale, shallow and elongated, with a dominant distribution in Xiaqu town. We analyzed the correlations between the landslide abundance and topographic, geological and hydro-meteorological factors. Our results indicated that the landslide abundance index is related to the gradient of the hillslope, distance from a river and total rainfall. The landslide area density, i.e., LAD increases with the increase in these influencing factors and is described by an exponential or linear relationship. Among all lithological types, Sinian mica schist and quartz schist (Sn-s) were found to be the most prone to landslides, with over 35% of landslides occurring in just 10% of the area. Overall, the lithology and rainfall characteristics primarily control the abundance of landslides, followed by topography. To gain a better understanding of the triggering conditions for shallow landslides, we conducted a physically based spatio-temporal susceptibility assessment in the landslide abundance area. Our numerical simulations, using the MAT.TRIGRS tool, show that it can accurately reproduce the temporal evolution of the instability process of landslides triggered by this event. Although rainfall before 8 May may have contributed to decreased slope stability in the study area, the short duration of heavy rainfall on 8 May is believed to be the primary triggering factor for the occurrence of massive landslides.

Monitoring and analysis of Woda landslide (China) using InSAR and Sentinel-1 data

Detecting the slow motions of highly elevated landslides in remote mountain areas has always been a problem. This paper takes the Woda landslide along the Jinsha River as an example to monitor landslide movement. Although some parts of the landslide body have been found to have moved in recent years, the timing and magnitude of motion have not been systematically monitored or interpreted. Here, we apply the SBAS time series strategy using 65-scene Sentinel-1A/B satellite InSAR images and study the spatial distribution and temporal behaviour of landslide movements between July 4, 2018, and August 29, 2020. Our research results show that the cumulative deformation on the left side of the landslide body with concentrated deformation was approximately 200 mm during the 2-year observation period. By calculating the relationship between the InSAR time series and the precipitation around the landslide, it is found that the landslide deformation is closely related to precipitation. GNSS technology is also deployed on the landslide mass and effectively complements InSAR technology. Simultaneously, based on the results of field surveys and hydrological data analysing the landslide's spatial deformation characteristics and deformation factors, the landslide deformation can also be inferred to be related to precipitation.

Scenario deduction of Natech accident based on dynamic Bayesian network: A case study of landslide accident in a liquor storage tank area in Guizhou Province, China

Industrial technical accidents caused by natural disasters are defined as Natech accidents, such as earthquakes and landslides, which can cause tremendous damage to industrial storage tanks, and lead to accidental leakage and even serious fire and explosion accidents. In this study, a landslide-induced storage tank accident model under earthquake disasters was proposed, and the relationship between landslide mass impact and target impact resistance was taken into account. Also, tank failure and the formation of the pool fire were considered to be the consequences of the Natech accident. Through scenario deduction, the dynamic process of landslide Natech was transformed qualitatively into a disaster chain network diagram composed of a scenario state, a disaster-causing factor and emergency management. The Bayesian network was used to learn and deduce the parameters of the network diagram, and in this process, the prior probability and conditional probability of nodes were obtained primarily by Monte Carlo simulation, and by an improved expert scoring method based on the fuzzy set theory. Through visualization software, the sensitivity analysis of landslide Natech was achieved. Finally, a case study of a liquor storage tank area in Guizhou Province, China was carried out, and the results show that a large amount of hazardous material leakage caused by buckling is key to the formation of pool fire accidents, and several prevention measures for earthquake-induced landslide Natech was proposed according to the sensitivity analysis.

A New Stress-reduction Model for Soil Arch in Landslides

Stabilizing piles are extensively used as an effective landslide control treatment, and the soil arching effect is the key element for the performance of the pile system. Most previous studies on soil arching effect and its application in stabilizing piles were conducted with laboratory tests and numerical simulations, while limited efforts have been dedicated to the analytical characterization of such a soil-structure interaction. In this paper, a new stress-reduction model for soil arch in landslides is established by theoretical derivation. Our model calculation has demonstrated an exponential reduction in the stress along the direction of slipping between and behind stabilizing piles and thus justifies the observations of laboratory tests and numerical simulations. Thereafter, the analytical solutions to the two key arch shape parameters, namely the inclination angle at the foothold and the thickness of soil arch, are derived based on the proposed stress-reduction model. Then, the ultimate bearing capacity of soil arch between and behind stabilizing piles is subsequently calculated, and a three-level load sharing model for landslides is thus proposed based on the stress-reduction mode. The load sharing model can well capture the stage characteristics of the interaction between landslide mass and stabilizing piles. Finally, the calculation model of spacing between stabilizing piles is established based on the proposed stress-reduction model, and it turns to be good in field application. The findings of this study can contribute to a better understanding of the soil arching effect as well as a better design of the stabilizing piles.

High Steep Rock Slope Instability Mechanism Induced by the Pillar Deterioration in the Mountain Mining Area

In hilly regions, landslides or slope failures are very common phenomena, when underground mineral resources are excavated. In this study, some landslide disasters in a mountain mining area were analyzed. The engineering geological and instability reason were investigated. The numerical simulation of a high steep rock slope disturbed by a room and pillar mine was established. The failure process of a high steep rock slope induced by the pillar deterioration was analyzed to reveal the characteristics of deformation and sliding. The results show that the pillar plays an important role in maintaining the stability of the slope, if the pillar can support the overlying rock mass, only a tiny deformation will be induced. When the pillar fails and the roof caves, the overlying rock mass above the room and pillar goaf will rapidly subside, and the crack evolution of slope is induced, forming the potential slip surface. The landslide mass gradually moves. When the rock mass at the middle and lower of the slope is squeezed out, slope sliding will be induced. The failure process can be divided into four stages as follow: tiny displacement is caused by the mining, roof collapse is caused by the pillar failure, the potential slip surface is formed from the crack evolution; the slope sliding is induced by the fracturing of rock mass at the middle and lower of the slope.

Automatic recognition of slide mass and inversion analysis of landslide based on discrete element method

The slip surface is an important structure for analyzing the landslide mechanism, and it will be deformed by the traction and shear of the slide mass. For the landslide accident without artificial monitoring, if the slip surface can be restored according to the slope morphology before and after the landslide, information such as the safety factor before the damage to the slope and the volume of the slide mass can be obtained by the position of slip surface, which helps engineers to analyze the cause of the landslide. In this paper, an automatic slide mass identification and landslide inversion analysis method based on discrete element simulation is proposed. The method combines Gaussian Mixture Model (GMM), alpha shape algorithm, discrete element simulation, and the morphology of the slope before and after the landslide to invert the slip surface of the slope. This method is suitable for two and three dimensional slope models. In addition, the effect of the slope angle on the deformation of the slip surface is analyzed.

Application of Stress Parameter from Liquefaction Analysis on the Landslide Induced Tsunami Simulation: A Case Study of the 2018 Palu Tsunami

The accuracy of numerical simulations of a landslide-induced tsunami depends on the landslide characteristics, such as landslide geometry and geotechnical parameters. However, owing to the difficulty in sampling and measuring submarine landslides, rough assumptions of landslide parameters typically lead to significant uncertainties. In the 2018 Palu event, the earthquake was followed by immediate cascading disasters of coastal subsidence, both land and submarine landslides and a tsunami. This scenario provides opportunities to analyze landslide phenomena on land to characterize the submarine landslide causing the tsunami. This study proposes a new approach of using shear-stress parameters obtained from liquefaction analyses as input for landslide-induced tsunami simulation. To obtain the submarine landslide parameter, using the finite element method we modeled the liquefaction happened in Jono-Oge located near Palu Valley area. The shear-stress in this area was quite small with the range 1.5–3.5 kPa. We found that tsunami simulation yielded better accuracy by applying the stress value range obtained from the liquefaction analysis on land (1.5 kPa) rather than the typically adopted stress value for general cases (20 kPa). The result from the tsunami simulation using two-layer method with identical landslide location and geometry showed that shear-stress value of landslide mass gave quite a significant effect to the tsunami height.

Landslide susceptibility and risk analysis in Benighat Rural Municipality, Dhading, Nepal

The complex geology and undulating terrain made Nepal vulnerable to natural disasters like landslides. Benighat-Rorang Rural Municipality (RM), in the Dhading district of Nepal's Bagmati province, has experienced several minor to massive landslides that have harmed both nature and civilization. This study examines the factors influencing landslides in the Benighat-Rorang RM by analyzing soil structure, geology, land cover, geomorphology (primarily slopes and aspects), fault lines, drainage density, weather data, and road density to generate a comprehensive Landslide Susceptibility Mapping (LSM). The LSM will help in identifying landslide-prone zones (high to low), which will, in turn, enable stakeholders to implement appropriate mitigation measures across the landslide-induced rural municipality. The current study intends to create Landslide susceptibility zonation mapping within and around the studied area by applying the AHP method while taking into account the optimal set of geo-environmental parameters to identify regions at risk of future landslides. Elevation, Slope, Aspect, Drainage, Geology, Soil Classes, Fault Line, Lineaments, Land-cover, Road Networks, Population, and climatic parameters (Rainfall, Temperature, Relative Humidity, Surface Pressure, and Wind Speed) are among the fourteen geo-environmental elements used for this research. Using the field verification approach, the results of this procedure have been validated, which can be observed in an estimated success rate curve. Meteorological factors, such as temperature, rainfall, relative humidity, surface pressure, and wind speed, have been examined regarding landslide susceptibility. Thus, an integrated assessment of landslide susceptibility was applied to the area to identify inhabited areas vulnerable to or at risk of landslides. Furthermore, the placement of public amenities throughout the research zone was considered while conducting the social vulnerability risk analysis. Finally, landslide susceptibility zonation, climatic factors influencing landslide susceptibility, and social vulnerability assessment results of the study area have been combined to generate a risk map identifying landslide-prone municipal facilities and vulnerable communities. This study will help in building resilient landslide communities through effective spatial urban planning that incorporates regional risks induced by landslides with infrastructure development and management strategies.

Weathering in landslide-prone areas: Evidences from hydrochemistry and sulfur isotopic compositions in the Bailong River, northeastern Qinghai-Tibet Plateau

Investigating weathering processes in landslide-prone areas is important for understanding the carbon budget due to weathering during mountain building. Here, we present the monthly hydrochemistry and sulfur isotopic compositions of SO42− (δ34S–SO42−) in the Bailong River which drained landslide-prone areas in the northeastern Qinghai-Tibet Plateau. Ca2+ and HCO3− were dominant in cations and anions respectively, and δ34S–SO42− values varied over a narrow range, from 5.1‰ to 6.7‰. We constrained the sources of major cations and SO42− through an inverse model and the mass balance model of δ34S–SO42−. The results showed that cations in the Bailong River were mainly from carbonate weathering, and sulfide oxidation was an important source of SO42−. Weathering in the Bailong River catchment showed an CO2 source over geologic timescales due to the reaction of H2SO4. The relationship between weathering fluxes and physical erosion rate indicated that high runoff facilitated physical erosion, and in turn accelerated chemical weathering. However, under the conditions of extreme discharge and physical erosion, SO42− fluxes from sulfide oxidation were not as high as expected, which was ascribed to the transport of old landslide deposits where most sulfides had been exhausted. Therefore, in tectonically active areas with massive landslides, the high erosion rate caused by landslides promoted chemical weathering, but sulfide oxidation did not respond sensitively to strong physical erosion under high runoff conditions. This study helped to understand the relationship among landslides, chemical weathering, and geologic carbon cycle.

EMERALD EXTRACTIVISM: BORDERS, ENERGY, AND DATA INFRASTRUCTURES IN IRELAND

In November 2020, a video surfaced on Twitter showing the earth moving underneath the feet of a local hillwalker. The video documented a massive peat landslide at the border between Ireland and Northern Ireland, caused by the construction of the Meenbog Wind Farm. The landslide destroyed a swathe of active peat bog and polluted a watershed which spanned both sides of the border, prompting governmental and legal action from agencies and organizations in Ireland, Northern Ireland, and UK. A key piece of the puzzle, however, was that the Meenbog Wind Farm had in 2019 sold its future energy to global logistics and cloud giant Amazon to power its data centre operations in Dublin, over 200km away from this wind farm site in rural Donegal. The data infrastructure company’s decarbonization efforts were following fault lines and toxic legacies of colonial expansion, the imagined perpetual growth of data systems having unintended consequences at Ireland's contested internal border. By analyzing data centre and energy policy, public discourse around these infrastructural systems, and drawing upon site-specific fieldwork, this paper will confront the re-organization of political and environmental relations at the border with regards to emerging renewable energy and data entanglements. Engaging with vibrant discourses of “green extractivism” during the transition to renewable energy, the paper will approach bordering mechanisms cutting through Ireland as sites of contestation about what present and future extractive energy and data supply chains will look like, who will bear their burdens, and who will have a voice in shaping them.

Physical and Numerical Simulation of the Mechanism Underpinning Accumulation Layer Deformation, Instability, and Movement Caused by Changing Reservoir Water Levels

Large-scale physical models of landslides can potentially accurately reflect the interactions between many internal and external factors and elucidate the process of slope deformation and failure. In order to reveal the mechanism of deformation of the reservoir bank accumulation layer, in this study, a large-scale physical test model with a similarity ratio of 1:200 was constructed based on the actual engineering geological section. Two reservoir water level cycle fluctuation conditions were simulated, and the reservoir water level drop rate was strictly controlled to be two times the rise rate. This study analyzed pore water pressure and deformation characteristics in the accumulation layer in relation to fluctuating reservoir water levels. The results showed that the rise in reservoir water level will make landslides more stable. The periodic sudden drop in water level seriously endangers the stability of landslides. The deformation and failure of landslides are more likely to occur in the weak interlayer area. The failure mode of the accumulation body in the test was traction failure. It is suggested that the front part of the accumulation body can be reinforced in practical engineering. To reveal the progression of instability and movement during accumulation layer large-scale landslides, a numerical model was constructed using the material point method. The accumulation layer sliding process could be divided into three stages: acceleration sliding, deceleration sliding and stabilization. After destabilization, the river channel may be altered by the landslide mass to form a landslide dam, potentially threatening the integrity of the dam via impulse waves generated during destabilization. The research results provide technical support for reservoir scheduling in major water conservancy and hydroelectric power station reservoirs as well as engineering risk assessment and prevention.

Hysteresis effect and seasonal step-like creep deformation of the Jiuxianping landslide in the Three Gorges Reservoir region

Slow-moving landslides are common in the Three Gorges reservoir (TGR) region. It may evolve into massive landslide hazards due to reservoir level fluctuation and rainfall. The assessment of slow-moving reservoir landslides is critical for the prevention and control of geological hazards. A step-like deformation mechanism for slow-moving landslides is proposed. Here, we use various wavelet tools to process the time series of 16 years continuous monitoring surface displacement of the Jiuxianping landslide at TGR. Then, the methods are used to investigate the correlation and hysteresis between the trigger factors (rainfall and reservoir level fluctuation) and reservoir landslide creep displacement. Owing to the influence of reservoir level fluctuation and rainfall, the triggering factors of displacement in different regions differ and show prominent hysteresis characteristics. Furthermore, the contribution of GPS monitoring points and InSAR fusion technology to creep landslide assessment is discussed, which can effectively reduce the possibility false alarms in landslide prediction. These mechanisms can be used to explain why some sliding bodies can keep stable after very large and long-time deformation. Therefore, these results are crucial for effective and reasonable geological hazard prevention and control in the TGR region.

Genetic mechanisms and a stability evaluation of large landslides in Zhangjiawan, Qinghai Province

It is important to study the instability law of typical landslides to understand the evolution of regional landslides and for disaster prevention. This study uses the Zhangjiawan landslide in Xining City, Qinghai Province, as an example. Through field surveys and an analysis of the geological environmental conditions, the formation and evolution mechanisms of the Zhangjiawan landslide are summarized. The stability of the Zhangjiawan landslide was evaluated using limit equilibrium and numerical simulation methods to provide theoretical support for the susceptibility of the Zhangjiawan landslide. The results show that the main reasons for the occurrence of multi-grade landslides are the steep and gentle terrain changes, the poor permeability of the mudstone lithology, the excavation of the front anti-slide section, and rainfall. The whole deformation and failure mechanism of the landslide is the “unloading rebound-tension deformation-creep deformation.” The results of the numerical simulation and the limit equilibrium methods are nearly the same, and the difference in the stability coefficients is small. Under rainstorm conditions, the displacement and the maximum shear strain increments are mainly concentrated on the rear edge of the landslide mass, and the front edge is pushed, which is a typical push-type landslide.