Large-scale Landslides Research Articles

Study on Optimal Pile Length in Load Section of Double-Row Buried Pile under Overtopping Failure Mode

An anti-slide pile is a common landslide control measure. Compared with the full-length pile whose top extends to the ground, the buried pile is more optimal in internal force distribution, saves material and has remarkable economic benefits. At present, there is a lack of in-depth theoretical analysis on the pile length of the load section of double-row buried piles. In order to establish the design calculation method of pile length in the load section of double row buried piles, this paper is based on the failure mode of overtopping. The design equation of load section pile length is obtained by using the transfer coefficient and limit equilibrium method. Taking a landslide in Yan’an City, Shaanxi Province, China, as an example, the reliability and economics of double-row buried piles are verified by comparing the treatment effects of single-row, double-row and double-row buried piles, and the engineering design is completed. The results show that the landslide control project using the design calculation method can meet the requirements of slope stability and at the same time save a quarter of the material compared with the double row of full-length piles. The engineering example proves the rationality and practicability of the design method and provides engineering reference value for the use of the double-row buried anti-slide pile structure in large-scale landslide treatment.

Probing multi-physical process and deformation mechanism of a large-scale landslide using integrated dual-source monitoring

The implementation of isolated heterologous monitoring systems for spatially distant borehole deployments often comes with substantial equipment costs, which can limit the effectiveness of geohazard mitigation and georisk management efforts. To address this, we have developed a novel monitoring system that integrates fiber Bragg grating (FBG) and microelectromechanical system (MEMS) techniques to capture soil moisture, temperature, sliding resistance, strain, surface tilt, and deep-seated inclination. This system enables real-time, simultaneous data acquisition and cross-validation analyses, offering a cost-effective solution for monitoring critical parameters in geohazard-prone areas. We successfully applied this integrated monitoring system to the Xinpu landslide, an active super-large landslide located in the Three Gorges Reservoir Area (TGRA) of China. The resulting strain profile confirmed the presence of two shallow secondary sliding surfaces at depths of approximately 7 m and 12 m, respectively, in addition to the deep-seated sliding surface at a depth of ∼28 m. The lower secondary sliding surface was activated by extreme precipitation, while the upper one was primarily driven by significant changes in reservoir water levels and secondarily triggered by concentrated rainfalls. Anti-slide piles have remarkably reinforced the upper moving masses but failed to control the lower ones. The gap between the pile heads and the soil amplified the rainwater erosion effect, creating a preferential channel for rainwater infiltration. Multi-physical measurements revealed a mixture of seepage-driven and buoyancy-driven behaviors within the landslide. This study offers an integrated dual-source multi-physical monitoring paradigm that enables collaborative management of multiple crucial boreholes on a large-scale landslide, and contributes to the evaluation and improvement of engineering measures in similar geological settings.

Analyzing vegetation recovery and erosion status after a large Landslide at Mt. Hakusan, Central Japan

A large-scale landslide occurred in 2015 in Senninvalley, Mt. Hakusan, Central Japan, releasing large amounts of sediment. To mitigate continuous erosion in the landslide area and its downstream adverse effects, reforestation activities were implemented from 2016 to 2021. This study assessed the status of vegetation recovery and erosion condition after 7 years using aerial photographs, light detection and ranging data, satellite imagery, and published documents. The results show that the greenery (herbaceous and woody plants) is mainly recovering on the upper slope of the landslide area where reforestation works were implemented, while the lower slope, where no reforestation activities have been applied, still lacks greenery. The lower slope suffered nearly 1–4 m of continued erosion from 2016 to 2022, while upper slope has no significant erosion. Within this 7-year period, the vegetation coverage on the upper slope of the landslide, where artificial restoration was applied, increased significantly from 10 to 43%.

Toward large-scale fine resolution DEM landslide simulations: periodic granular box for efficient modeling of excavatable slope

Understanding landslide hazards and developing mitigation measures is critical to protecting lives and property. The Discrete Element Method (DEM) has demonstrated its ability to simulate landslides and estimate impact forces on mitigation structures. Such simulations often model slope surfaces as bedrock on which a fixed amount of earth mass is released and slides. Mass entrainment due to local failure of an excavatable slope surface is rarely modeled with sufficient resolution. Fine-resolution modeling of an excavatable slope for simulation is necessary and non-trivial to improve DEM simulations of large-scale landslides. In this study, we present a method based on Periodic Granular (PG) boxes for efficient modeling of excavatable slopes. A PG box is a packing of particles in a quasi-static state inside a virtual unit box, where the periodic boundary conditions are satisfied at the box surfaces. The procedures used to construct a PG box are presented. The quality of PG boxes is analyzed both at the particle contact scale and at the laboratory specimen scale by measuring contact orientation statistics and by performing numerical triaxial tests. As a demonstration, a centimeter resolution slope model constructed using the PG box-based method is presented using topographic data for the Aso Bridge landslide. In addition, landslide simulations to verify the excavation effect were performed on sub-meter resolution slope models. Our simulations show that landscape shape and particle size have a direct effect on the movement and deposition of earth masses. This highlights the need for detailed 3D terrain modeling and further study of particle size effects. By constructing the first excavatable DEM slope model with billions of centimeter-sized particles, this study can be considered a solid step toward fine-resolution DEM simulations of large-scale landslides, which can contribute to both scientific understanding and engineering countermeasures to mitigate the catastrophic consequences of large-scale landslides.

Research on Development Characteristics and Landslide Dam Hazard Prediction of Zhuangfang Landslide in the Upper Reaches of the Nu River

The upper reaches of the Nu River have strong tectonic activities and broken rock mass structures, often causing landslide disasters. The Zhuangfang landslide has apparent signs of surface deformation, and there is a risk of further sliding and blocking of the river. Taking the Zhuangfang landslide as an example, this paper analyzes the development characteristics and stability through geological field surveys, a drone aerial survey, field drilling, and GEO5 geotechnical engineering software. Then through the indoor tests and RAMMS numerical simulation software, the parameters of the landslide are determined, and the risk of a landslide dam is analyzed. Our results demonstrated that the Zhuangfang landslide is a large-scale landslide with a volume of about 4.5 × 106 m3. The front edge of the landslide is seriously deformed and is in an under-stable state, with risks of sliding and river blockage. The numerical simulation results showed that the total movement time of the landslide was 130 s, and the landslide entered the Nu River at 55 s. However, the landslide does not completely block the river and cannot form a landslide dam. The study proposed a parameter inversion method to determine the landslide mass parameters based on RAMMS numerical simulation software. The related results of this study can provide a reference for the sustainable development of the ecological environment in the Nu River Basin.

KEY ROLE OF FOSSIL SEAWATER IN NEOGENE SEDIMENTARY ROCKS FOR LANDSLIDE OCCURRENCES IN THE NORTHERN PART OF CENTRAL JAPAN

The south-western area of Niigata Prefecture has the highest landslide densities in Japan. Saline groundwater emerges from several landslides in this area and is an influential factor in the occurrence of these landslides. The geochemical approaches to groundwaters and application of the electromagnetic surveys for landslide slopes revealed the hydrogeological structure of the large-scale landslides which was located on the outlet of saline waters from deep reservoirs and landslide-prone area where wide zonal distributions of saline water at depths of more than 50–100 m and fresh water at depths of shallower than 50–100 m. It is most likely that the saline groundwater behavior emerging in large-scale landslides is controlled by injections of the geo-pressured saline waters from deep reservoirs. The injection of the geo-pressured waters into the landslide mass likely results in excess pore pressure, which is a possible cause of landslide occurrence. On the other hand, the shallow fresh groundwater is inferred to be meteoric water of origin that replaced the saline groundwater, which likely weakened the shear strength of bedrocks, resulting in landslides. Thus, pore saline water plays an important key role in the occurrence of landslides, both large-scale landslides with low frequency and common landslides.

Method of strain analysis of pipelines under landslides: An improved semi-analytical method for softening bending moment-curvature

The accurate description of the elastic‒plastic stress‒strain of a pipeline is used to evaluate the risk that the pipeline will undergo failure during a landslide. This paper proposes a complete set of refined semi-analytical methods (SAMs) for pipeline elastic-plastic strain to accurately evaluate the safety of pipelines. First, a concise model for the calculation of landslide thrust is established based on the pipe-soil interaction mechanism as load boundaries of the SAMs. Secondly, the plastic softening bending moment-curvature relationship (BMCR) is derived to establish a difference equation for the deformation of the pipeline during the plastic stage based on the principle of internal force balance of the pipe section, and then the bending plastic strain is calculated accurately. Finally, the axial strain is fully calculated considering the interaction between axial force and bending of the pipeline. The comparison of the results of small-scale landslide tests, large-scale landslide tests, and SAM calculations shows that the improved SAM has good applicability, with 20% better accuracy than traditional methods. In conclusion, the SAM proposed in this paper can effectively guide the design and evaluation of the strain-based design pipeline.

Toward a sound understanding of a large-scale landslide at a mine waste dump, Anshan, China

Toward a sound understanding of a large-scale landslide at a mine waste dump, Anshan, China

Quantitative Evaluation of Suspended Solid Runoff from Large-Scale Landslide Areas Presumed to Be the Source of Turbid Water

In the uppermost stream of the Mimikawa River, in northern Miyazaki Prefecture, the contribution to river turbidity of a huge, collapsed slope alternating sandstone and mudstone layers was qualitatively shown in our previous study. In this study, the water level and turbidity were continuously observed, to obtain a quantitative estimation of this contribution. The conversion equation from the water level to the flow rate is required, but field measurements during the flooding term in the mountainous site are difficult. In this study, a high-resolution survey was conducted, and the relationship was determined via a small-scale hydraulic model shaped using a 3D printer from the survey results, to determine the relationship between the water level and the flow rate. The flow rate time series was reproduced with the distributed runoff model that is verified with the flow rate converted from the water level. The flow rate and turbidity load time series were also estimated from the long-term rainfall. The area of the bare soil surface of each small basin was obtained via satellite image analysis, and the soil yield from each surface condition was calculated. Furthermore, the amount of turbidity produced upstream of Kamishiiba Dam was calculated for each small basin. It was estimated that 24% of the turbidity was generated from the small basin covering 5.7% of the total catchment area. This study showed that it is possible to verify the hydrological model by obtaining the water-level–discharge relationship, even in the mountains, where it is difficult to observe the discharge on-site, via small-scale hydraulic model experiments.

Failure mechanism of large-scale landslide in the central Nepal Himalaya

The geomorphological and geological characteristics of central Nepal reflect the dynamic nature of tectonic and mass movement processes that lead to the occurrence of large-scale landslides (LSLs). The mechanism of the LSL failure process is not well understood due to the different deformation stages controlled by geological structures and causative/ triggering factors. Regional tectonic structures and local rock mass characteristics play a vital role in the formation of LSLs. Engineering geological characterization was performed to evaluate the rock/soil properties, and the associated state of danger (cracks, seepage, etc.). The rock mass rating (RMR) and geological strength index (GSI) methods were used to estimate rock mass quality and strength parameters. The estimated strength parameters together with laboratory test data were used to set up a two-dimensional (2D) landslide surface to simulate the failure scenarios. The simulation of landslide models was iterated under different loading conditions by incorporating geological heterogeneities. The results have demonstrated that the movement of the slope was affected by different stress conditions over time, which were verified using spatiotemporal landslide data. The landslide exhibited a three-stage failure mechanism with the development of tension-induced cracking at the rear and shearing failure of the critical locking section in the middle section. The tension shear and joint-step-path rupture along joint surfaces occurred during different stages of the landslide failure processes. The simulated results showed that the genetic development of LSL is mainly attributed to the geological structures and sudden changes in stress conditions. Thus, the research outcomes can be illustrative to evaluate the role of geological discontinuities, geotechnical parameters and triggering effects by the numerical simulation techniques for the failure mechanism of LSLs.

Slope stability issues of Bukula Landslide in Raghuganga Hydropower Project

Slope stability concerns hold global significance among researchers, professionals, and academicians. Despite various research studies, geological and geotechnical investigations on landslides, there is still a lack of proper and comprehensive landslide hazard study, accurate data acquisition, and effective monitoring mechanism in Nepal. The objective of this present study is to identify the type of failure, causes and effects of landslide and possible mitigation measures of Bukula Landslide located within Raghuganga Hydropower Project in Myagdi. This landslide is a large-scale landslide that spans over 500 meters with vertical relief exceeding 300 m. Based on visual inspection, wedge, toppling, and buckling failures prevail within the landslide. The bedrock is thinly foliated and moderately jointed, while 3 m long tension cracks are observed along the foot trail across the landslide area, indicating that the slope is unstable. Notably, buckling failures are common in highly jointed bedrock with low RQD. Likewise, sheared zones/weak zones were observed within the landslide area. The geological survey, kinematic analysis and numerical simulations of the hillslope revealed that Bukula landslide was triggered by sheared rock mass and river toe cutting. To mitigate the problems caused by the landslide, proper support structure installation and drainage system design are necessary.

Spatial variability of slope movements in central and western Nepal Himalaya: Evaluating large-scale landslides to cut-slopes

Spatial variability of slope movements is common in the Himalayan terrain of central and western Nepal Himalaya due to the intricate topography, differential geo-environment, and frequent rainstorms. The process of mass movements in the Himalaya has been described in the past by many researchers. The spatial variability of slope movement phenomena is scale dependent and is affected by causative and triggering processes. The limited researchers delivered output to understand the scale-dependent spatial variability resulting from the causative and triggering mechanism of slope movement phenomena. This study has presented a rigorous scientific examination of the spatial variability of slope movements, focusing on large-scale landslides to cut slopes across the central and western regions of the Nepal Himalaya. To achieve this, a multidisciplinary approach was employed, encompassing geospatial analysis, remote sensing, and field investigations. High-resolution satellite imagery was utilized to identify and map slope movement features, while digital terrain analysis techniques aided in quantifying their characteristics. This approach quantitatively analyzed slope movement distribution, frequency, and characteristics in terms of various geo-environmental settings. The findings reveal diverse patterns of slope movements influenced by complex interactions between geological factors, geomorphology, triggering factors, and anthropogenic activities. Geological and geomorphological heterogeneity play roles differently in the spatial distribution of slope movements. Moreover, rainfall distribution and peak ground acceleration act similarly for the scale dependency phenomena of slope movement. The spatial variation concerning the causative and triggering variables signify the scale-dependency nature of slope movement processes. This study has provided insights into the scale dependency and spatially variable nature of slope movement events due to variations in causative and triggering mechanisms in the Nepal Himalaya.

Insights into some large-scale landslides in southeastern margin of Qinghai-Tibet Plateau

The Sichuan–Tibet railway (STR), beginning from Chengdu in Sichuan Province and ending in Lhasa in Tibet Autonomous Region, runs across the southeastern margin of the Qinghai–Tibet Plateau (QTP). Due to intense tectonic activity, deeply incised valleys, high geostress and frequent earthquakes, the STR area is of a typical large landslide-prone area. To gain insights into large landslides along the STR, an area covering 3.34 × 105 km2 that extends 80–150 km on both sides of the railway was used to examine the spatial distribution and corresponding characteristics of landslides. The results showed that the study area contains at least 629 large landslides that are mainly concentrated on 7 zones (zones I–VII). Zones I–VII are in the southern section of the Longmenshan fault zone (with no large river) and sections with Dadu River, Jinsha River, Lancang River, Nujiang River and Yarlung Zangbo River. There are more landslides in the Jinsha River section (totaling 186 landslides) than the other sections. According to the updated Varnes classification, 408 large landslides (64.9%) were recognized and divided into 4 major types, i.e. flows (275 cases), slides (58 cases), topples (44 cases) and slope deformations (31 cases). Flows, which consist of rock avalanches and ice–rock avalanches, are the most common landslide type. Large landslide triggers (178 events, 28.3%) are also recognized, and earthquakes may be the most common trigger. Due to the limited data, these landslide type classifications and landslide triggers are perhaps immature, and further systematic analysis is needed.

Effects of Tectonic Setting and Hydraulic Properties on Silent Large-Scale Landslides: A Case Study of the Zhaobishan Landslide, China

Unlike strong earthquake-triggered or heavy rainfall-triggered landslides, silent large-scale landslides (SLL) occur without significant triggering factors and cause unexpected significant disaster risks and mass casualties. Understanding the initiation mechanism of SLLs is crucial for risk reduction. In this study, the mechanism of the Zhaobishan SLL was investigated, and the SLL was jointly controlled by weak-soil (fractured rock mass) and strong-water (abundant water replenishment) conditions under the impact of active tectonism and complex hydraulic properties. Strong tectonic uplift, high fault density, and historical earthquakes led to weak-soil conditions conducive to the Zhaobishan SLL. The combined effect of unique lithology, antiform, and cultivated land contributed to the water replenishment characteristics of extensive runoff confluence (3.16 times that of the landslide body) and supported long-distance groundwater replenishment, thereby forming strong-water conditions for the landslide. The amplified seepage amount caused the strength of the soil mass on the sliding surface to decrease to 0.4 times its initial strength, eventually triggering the Zhaobishan SLL, which occurred 4.6 days after the peak rainfall. Moreover, the landslide deposits have accumulated on the semi-diagenetic clay rock, thereby controlling the subsequent recurring debris flows in the Lengzi Gully. To reduce disaster risk of SLL in vulnerable mountainous regions, the water confluence area behind the main scarp of the landslides and the hysteresis characteristics between landslides and peak rainfall should be further considered, and recurring debris flows following massive landslides also should be focused.

Simulation of shallow landslides induced by typhoon in July 2018 in Gogoshima, Ehime Prefecture, Japan based on a simple model

Every year, many typhoons make landfall in Japan causing disasters on mountain slopes across the country. Rainfall induced landslides in Japan mostly occur at shallow depths. Developing simple models of rainfall-induced landslides provides a practical alternative to finite element methods in large-scale landslide modelling and prediction. Therefore, authors previously developed a simple method to calculate the advance of the wetting front into fine sand slopes subjected rainfall. However, during intense rainfall, the excess rainfall that cannot be absorbed into the soil will generate runoff on the slope surface, which has not been included in the previous model. Thus, this study integrated the model with a surface water modeling module to simulate the disasters more comprehensively. The surface water is controlled by 2D shallow water equations and the digital elevation model depression removal process. The combined model is able to provide the maps of the wetting front, surface water depth, and factor of safety of slope during rainstorms. The newly integrated model was used to simulate rainfall-induced disasters in the Gogoshima Island during the July 2018 typhoon. The simulation results disclosed that both moving of the wetting front and surface water flows contributed to shallow landslides along catchments in this island.

Landslide Hazard Assessment in Highway Areas of Guangxi Using Remote Sensing Data and a Pre-Trained XGBoost Model

This study presents a novel method for assessing landslide hazards along highways using remote sensing and machine learning. We extract geospatial features such as slope, aspect, and rainfall over Guangxi, China, and apply an extreme gradient boosting model pre-trained on contiguous United States datasets. The model produces susceptibility maps that indicate landslide probability at different scales. However, the lack of accurate data on historical landslides in Guangxi challenges the model evaluation and comparison between regions. To overcome this, we calibrate the model to fit the local conditions in Guangxi. The calibrated model agrees with the observed landslide locations, implying its capability to capture regional variations in landslide mechanisms. We apply the model at a 30 m resolution along the Heba Expressway and validate it against reports from July 2021 to March 2022. The model correctly predicts five of seven landslide events in this period with a reasonable alarm rate. This framework has the potential for large-scale landslide risk management by informing transportation planning and infrastructure maintenance decisions. More data on landslide timing and human disturbance events may improve the model’s accuracy across diverse geographical areas and terrains.

Detecting Recent Dynamics in Large-Scale Landslides via the Digital Image Correlation of Airborne Optic and LiDAR Datasets: Test Sites in South Tyrol (Italy)

Large-scale slow-moving deep-seated landslides are complex and potentially highly damaging phenomena. The detection of their dynamics in terms of displacement rate distribution is therefore a key point to achieve a better understanding of their behavior and support risk management. Due to their large dimensions, ranging from 1.5 to almost 4 km2, in situ monitoring is generally integrated using satellite and airborne remote sensing techniques. In the framework of the EFRE-FESR SoLoMon project, three test-sites located in the Autonomous Province of Bolzano (Italy) were selected for testing the possibility of retrieving significant slope displacement data from the analysis of multi-temporal airborne optic and light detection and ranging (LiDAR) surveys with digital image correlation (DIC) algorithms such as normalized cross-correlation (NCC) and phase correlation (PC). The test-sites were selected for a number of reasons: they are relevant in terms of hazard and risk; they are representative of different type of slope movements (earth-slides, deep seated gravitational slope Deformation and rockslides), and different rates of displacement (from few cm/years to some m/years); and they have been mapped and monitored with ground-based systems for many years (DIC results can be validated both qualitatively and quantitatively). Specifically, NCC and PC algorithms were applied to high-resolution (5 to 25 cm/px) airborne optic and LiDAR-derived datasets (such as hillshade and slope maps computed from digital terrain models) acquired during the 2019–2021 period. Qualitative and quantitative validation was performed based on periodic GNSS surveys as well as on manual homologous point tracking. The displacement maps highlight that both DIC algorithms succeed in identifying and quantifying slope movements of multi-pixel magnitude in non-densely vegetated areas, while they struggle to quantify displacement patterns in areas characterized by movements of sub-pixel magnitude, especially if densely vegetated. Nonetheless, in all three landslides, they proved to be able to differentiate stable and active parts at the slope scale, thus representing a useful integration of punctual ground-based monitoring systems.

Dynamic Response Law and Failure Mechanism of Slope with Weak Interlayer under Combined Action of Reservoir Water and Seismic Force

The southwestern region of China is close to the Eurasian earthquake zone. Many engineering areas in southwestern China are affected by earthquakes and are close to the epicenter of earthquakes that occur in this region. During earthquakes, slopes with weak interlayers are more likely to cause large-scale landslides. In response to the low stability of slopes with weak interlayers in reservoir dam areas, the dynamic response law and failure mechanism of weak interlayered slopes under the combined action of reservoir water and seismic forces were studied through shaking table model tests and finite element numerical simulation software. The height of the water level and the size of the seismic waves were changed during these tests. The research results indicate that seismic waves are influenced by weak interlayers and are repeatedly superimposed between the weak interlayers and the slope surface, resulting in an acceleration amplification effect that increases by approximately 1.8 times compared to homogeneous slopes. Vertical earthquakes have a significant impact on the dynamic response of slopes, and their peak acceleration amplification coefficient can reach 0.83 times the horizontal peak acceleration. The stability of weak interlayers during earthquakes is the worst within the range of the direct action of reservoir water. The failure mode of a slope is as follows: earthquake action causes cracking in the upper part of the slope, and as the earthquake increases in intensity, and the infiltration of reservoir water intensifies, the cracks expand. The soft and muddy interlayer in the front section of the slope forms a sliding surface, and ultimately, the sliding failure forms an accumulation body at the foot of the slope. In reservoir dam areas, the stability of a slope is closely related to the engineering safety of the reservoir dam. Therefore, when a strong earthquake and the water level in a reservoir jointly affect a weak-interlayer slope, the slope is in the stage of plastic deformation and instability. The stability of the slope may be overestimated, and the slope is likely vulnerable to sliding instability, which needs to be monitored and treated.

Quantitative long-term (1922 to 2021) monitoring of a large-scale landslide of a LIA lateral moraine due to glacial debuttressing

Quantitative long-term (1922 to 2021) monitoring of a large-scale landslide of a LIA lateral moraine due to glacial debuttressing

Identifying the Groundwater Sources of Huangtupo Landslide in the Three Gorges Reservoir Area of China

Groundwater plays a crucial role in triggering and reactivating deep-seated landslides. However, classical hydrogeological investigations have limitations in their applicability to deep-seated landslides due to anisotropic and heterogeneous media. The Huangtupo landslide in the Three Gorges Reservoir area has garnered significant attention due to its high hazard potential. Of particular interest is the NO.1 Riverside Sliding Mass (HTP-1), which has shown notable deformation and has become the primary focus of landslide research. The study aims to investigate the sources of water in the HTP-1 landslide through hydrochemical analysis. This was achieved by monitoring the major ion content in the groundwater within the landslide for one year. Furthermore, stable isotope investigations were conducted on the groundwater in and around the landslide area, and an analysis of the mineral composition of the landslide soil was also performed. The results indicate that the groundwater in the landslide area (LGW) is a mixture of karst groundwater (KGW) from the adjacent upslope and local precipitation (LP). The karst groundwater is a major contributor to the recharge of the landslide groundwater system, causing a high component of groundwater that can easily exceed the critical level that causes landside failure during heavy rainfall events. Furthermore, prior to the relocation of residents from the Huangtupo landslide, the landslide groundwater was also impacted by human sewage, which not only affected the chemical composition of groundwater, but also had potential implications for slope stability. These findings provide a more scientific basis for the design and implementation of interception and drainage measures for the Huangtupo landslide and other large-scale landslides with similar geological conditions in the Three Gorges Reservoir area.