Slope Collapse Research Articles

Exogenous relief-forming processes and phenomena on the territory of the Chechen Republic

Landslide, also known as landslide, is a geological phenomenon that includes a wide range of ground movements such as rockfalls, deep slope collapse and shallow mudflows. Landslides can occur at sea, on the coast and on land. While gravity is the main driving force behind a landslide, there are other factors that affect the initial stability of the slope. Typically, preconditions create certain subsurface conditions that make the site / slope prone to collapse, while the actual landslide often requires a trigger before being triggered. Landslide studies help identify weak areas, classify hillsides into different categories, and minimize the impact of landslides.

WAVE GENERATION DUE TO DEBRIS FLOW INTO A SMALL AREA OF WATER

It is known that the tsunami is generated by the debris flow due to slope collapse into the sea. The huge waves may cause damage to coastal structures and residents. Because of heavy rain in northern parts of Kyushu Island, Japan, in July 2017, many reservoirs were damaged and were destroyed. It has been reported that the huge waves may have been caused by debris flow due to the heavy rain. Many laboratory experiments and numerical simulations of the landslide-generated tsunami into the sea have been carried out to clarify the process of wave generation. However, there are a few studies of wave generation by debris flow into a small area of water such as a reservoir. In this study, model experiments of debris flow were conducted in a two-dimensional flume and numerical models based on the depth-averaged shallow water equations have been per-formed in order to clarify the hydraulic characteristics of the waves.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/r6r72KtkvL4

The Impact of Agricultural Irrigation on Landslide Triggering: A Review from Chinese, English, and Spanish Literature

Landslides are considered a natural process, with hundreds of events occurring every year in many regions of the world. However, human activities can significantly affect how stable a slope or cliff is, increasing the chances of slope collapses. Moreover, agricultural irrigation has potential to saturate subsurface materials well below ground level and is known to be an important factor that can trigger landslides in many countries. A macroregional literature review of irrigation-induced landslides was developed in this investigation, considering what has been published in Chinese, English, and Spanish. A total of 115 peer-reviewed papers, books and book chapters, graduate and undergraduate theses, and government reports were found, including 82 case studies (23 in Chinese, 26 in English, and 33 in Spanish). Results from this analysis indicate that studies focusing on this important topic have increased exponentially since the 1960s, with most irrigation-induced landslides occurring in dry climates (precipitation less than 600 mm/year), with rainfall concentrated during summer months. The majority of studies have been done in the loess region of China (Asian region), followed by Peru (Latin American region), though cases were found from other macroregions (African, Indian, Russian, Angloamerican, and Indonesian). Based on this global review, new agricultural irrigation projects located in collapsible areas must include a landslide risk analysis. Cultivated areas can follow a series of measures to minimize the chances of triggering a landslide, which would put human lives, ecosystems, food production, and infrastructure at risk.

Different aspects of slope failures considering large deformation: application of smoothed particle hydrodynamics (SPH)

Understanding the insight of slope collapse is necessary for effective hazard mitigation policy. The conventional method may not be able to capture the actual failure mechanics as these methods are based on simplified assumptions of the predetermined slip surface. Highlighting this real engineering problem, an attempt is made in this research to simulate different aspects of slope collapse numerically. Lagrangian particle-based continuum model, namely, smoothed particle hydrodynamics (SPH) has been used to develop a three-dimensional numerical slope model to understand the failure mechanics of unstable slopes. Both homogeneous and non-homogeneous slope models have been simulated, and the time history of naturally occurring failure planes has been tracked. A distinct slip surface has been seen from displacement contour of particles, which portray the innate response of a collapsed slope. The effect of soil properties on the response of slope surface has also been evaluated quantitatively by the different combination of non-homogeneous slope models. Afterwards, two conventional remedial measures have been simulated, and significant reduction of run-out length is seen, which can put a spotlight on future mitigation strategy in geotechnical hazard.

Detection and Assessment of a Large and Potentially Tsunamigenic Periglacial Landslide in Barry Arm, Alaska.

The retreat of glaciers in response to global warming has the potential to trigger landslides in glaciated regions around the globe. Landslides that enter fjords or lakes can cause tsunamis, which endanger people and infrastructure far from the landslide itself. Here we document the ongoing movement of an unstable slope (total volume of 455 × 106 m3) in Barry Arm, a fjord in Prince William Sound, Alaska. The slope moved rapidly between 2010 and 2017, yielding a horizontal displacement of 120 m, which is highly correlated with the rapid retreat and thinning of Barry Glacier. Should the entire unstable slope collapse at once, preliminary tsunami modeling suggests a maximum runup of 300 m near the landslide, which may have devastating impacts on local communities. Our findings highlight the need for interdisciplinary studies of recently deglaciated fjords to refine our understanding of the impact of climate change on landslides and tsunamis.

Slope stability evaluation using backpropagation neural networks and multivariate adaptive regression splines

Abstract Slope stability assessment is a critical concern in construction projects. This study explores the use of multivariate adaptive regression splines (MARS) to capture the intrinsic nonlinear and multidimensional relationship among the parameters that are associated with the evaluation of slope stability. A comparative study of machine learning solutions for slope stability assessment that relied on backpropagation neural network (BPNN) and MARS was conducted. One data set with actual slope collapse events was utilized for model development and to compare the performance of BPNN and MARS. Research results suggest that BPNN and MARS models can model the relationship between the safety factor and the slope parameters. Also, the MARS model has the advantages of computational efficiency and easy interpretation.

Composite collapse mechanism of an anti-dip rock slope

Collapse is a common instability mode of anti-dip rock slopes. This type of failure involves a complex geo-mechanical process. This work investigated the collapse mechanism of an anti-dip rock slope in a granite mine in Shanxi Province, China. A detailed field survey was carried out to analyze the inducing factors and failure process of collapse. Then, discrete element numerical simulations were conducted by the Universal Distinct Element Code (UDEC) to determine the microscopic damage and macroscopic failure of collapse. Through these works, the composite collapse failure mechanism of the anti-dip rock slope was investigated comprehensively. Results show that the structural planes perpendicular to the slope surface and the steep anti-dip structural planes are the prerequisites of collapse. Strength softening of the structural planes caused by rainfall is the triggering factor of collapse. The collapse of such a rock slope can be considered as a composite failure composed of shear sliding, block toppling, and flexural toppling. In addition, the numerical results indicate that the composite failure of shear sliding and block toppling occurs at the toe of and the middle of the slope, followed by flexural toppling failure at the rear edge of the slope. Therefore, the monitoring and treatment of such type of collapses should be concentrated on the composite failure zone where shear sliding and block toppling occur. The high consistency between the numerical results and field observations shows the feasibility and rationality of using UDEC to study such collapse from the microscopic damage to macroscopic failure. The results enrich the type of collapse of anti-dip rock slopes and provide a scientific reference to the design treatment for such slopes.

New Landslide Disaster Monitoring System: Case Study of Pingding Village

The Linbeiken area is located in the village of Pingding, Taiwan. Since the Mindulle and Aere Typhoons in 2004, and as a result of the landslide triggered by the continuous heavy rainfall on 9 June 2006, there has been a persistent collapse of side slopes in the area. This paper describes the equipment that was installed to collect on-site topographic and hydrological information in the Linbeiken area upstream of the Pingding River and to monitor changes in the landslide area, as well as the measurements that were collected during the 2008 Typhoon Sinlaku. A case study of a landslide in Pingding, Taiwan was used to monitor the accurate coordinate changes in the potential landslide areas during typhoons. The goal of this study was to establish warning indexes, and to strengthen the software and hardware at the local disaster response center in the hope of gaining a full idea of the surface movement in landslide areas in future flood seasons. This is important for boosting the preparedness to adapt to landslide hazards, for improving disaster warnings, and for reporting efficiently to better protect the lives and property of local residents. The results show that the landslide disaster monitoring and warning system in Taiwan, as applied during Typhoon Sinlaku in 2008, is both effective and comprehensive.

Multi-phase flow simulation of impulsive waves generated by a sub-aerial granular landslide on an erodible slope

This study uses a multi-phase flow model to examine the impulsive waves generated by collapse of steep slopes at a water body. Possible effects of slope’s erodibility on the motion of the landslide and the resulting waves are investigated by comparing a sub-aerial landslide on a rigid slope to that on an erodible slope. Key parameters that are relevant to the generation of the impulsive waves are examined, including the time series of the elevation and location of first wave crest, the location and thickness of granular flow front, submerged granular volume, and potential and kinetic energy for water and granular landslide. Before it is free from the influence of the granular front, the generated wave is a forced wave traveling at the speed of the granular flow front. The first wave crest is about to leave the granular flow front when the speed of the granular front is close to the celerity at which a free long wave can propagate in the water above the granular front, and the maximum height of the first wave crest is reached at the time when the first wave has completed its transition from a forced wave to a free wave. It appears that the erodible slope can increase (1) the volume of the granular material plunged into water, (2) the thickness of granular flow front, and (3) the height of the first wave generated by the landslide. However, the total volume of the granular material plunged into water is not directly related to the height of the first wave.

Prediction model of the collapse of bank slope under the erosion effect of wind-induced wave in the Three Gorges Reservoir Area, China

During the storage period of the Three Gorges Reservoir, the bank erosion caused by wind-induced wave is getting more serious, especially for the crushed stone soil bank. The continuous wave scouring and erosion destabilize the bank slope and even induce the occurrence of landslides. Based on the energy conservation theory, the bank slope will reach a stable state after continuous wave erosion. Regarding this, this paper derives the prediction formula of the stable slope angle and erosion width when the wave erodes the crushed stone soil bank slope. Model tests on bank slopes with different dry densities and different crushed stone contents under the action of waves were conducted to observe the erosion process of wave-induced crushed stone soil bank slope and verify the proposed prediction formula. The results show that under the action of wave erosion, erosion ridge and collapse steep angle would form at the upper edge of the bank slope and the controlling factors of this process are the dry density of the crushed stone soil and the wave energy. When the content of crushed stone soil gradually increases, the ability of the bank slope to resist wave erosion weakens at first and then gradually strengthens. Comparing the erosion stable slope angle obtained from the model tests with the calculated results using the proposed prediction formula, a linear relationship could be observed, indicating that the proposed prediction formula is reliable for further analysis.

Effect of vertical distance of geogrid layers on slope stability

The landslide that occurred on the Meulaboh - Geumpang road section on May 10, 2017, resulted in the interruption of land transportation connecting West Aceh Regency and Pidie Regency, Aceh Province. The landslide on this road had an impact on the obstruction of logistics distribution and other needs from the direction of Meulaboh to Geumpang and vice versa. Based on these problems, the appropriate solution is needed in the prevention and planning of slopes to prevent landslides from happening again. This research was carried out by analyzing the slope stability under natural slope conditions and analyzing the slope stability of the conditions given slope reinforcement in the form of geogrids. Slope stability analysis is performed using the finite element method. The slopes are given alternative geogrid reinforcement with varying vertical distances. The variation of vertical geogrid distance is adjusted to the condition of the curve of the natural slope collapse before reinforcement. Based on the analysis of slope stability for natural conditions without reinforcement (existing condition), the safety factor values (SF) obtained at STA 84 + 280 and STA 84 + 910 were respectively 1.14 and 1.16. The results of the analysis of the slope stability that has been given reinforcement show that the vertical geogrid distance influences the slope safety factor.

Internal Erosion Failure of Uniform Sands under Confinement and Constricted Seepage Exit

Seepage water may move soil particles and cause internal erosion of soils, leading to sinkholes and the collapse of embankments and slopes. To account for the effects of confinement and constricted seepage exit, a test apparatus was developed to study the internal erosion of granular soils under various confining pressures, particle sizes, and sizes of the seepage exit opening. As indicated in the literature, the behavior of internal erosion has been largely studied by laboratory experiments and field investigations, and mechanical models that help describe the failure mechanism of internal erosion are less prevalent. A hydro-mechanical model that incorporates the fluid drag force and the shear strength of soil was therefore developed for quantifying the internal erosion experiments conducted in this study. The experimental results showed that the greater the confining pressure or the particle size, the greater the critical velocity; the greater the seepage exit opening, the smaller the critical velocity. The critical velocity predicted by the proposed hydro-mechanic model compares reasonably well with the experimental data. In addition to the confining pressure, particle size, and size of the seepage exit opening, the proposed model also showed that the friction angle and porosity of the soil are factors influencing the critical velocity, which is consistent with the experimental findings of this study.

Airblasts caused by large slope collapses

AbstractLarge slope collapses have been known to trigger extreme rushes of air loaded with projectiles (airblasts) capable of causing destruction and fatalities far beyond run-out of the rock mass. An appraisal of the likelihood of a destructive airblast should be a component of landslide risk assessments. Yet there is an absence of risk studies directly examining landslide-related airblasts. In this work we back-analyze an unreported airblast in the Sikkim Himalayas (India) and several other airblasts documented around the world. We explore the conditions a large slope collapse should meet to trigger a significant airblast, and we establish a semi-empirical relationship linking the potential energy in a collapse with airborne trajectory and the extent of the related airblast. The collapse of thousands or millions of cubic meters falling from a significant height results in a sudden release of energy (1011J to 1013J) and a high degree of comminution of rocks, causing a violent displacement of air. Average wind speeds of airblasts following impacts with airborne trajectory can be double the speed of rock avalanches. The size of the damage zone depends on the potential energy of the falling rock mass and can be amplified or reduced depending on how confined the valley is where the airblast occurs.

Logical Information Model for Prediction of Reservoir Slope Stability in Water Environment Control Project

Zhang, G.Q.; Feng, W.K.; Qi, Y.; Zhou, Y.J., and Yang, J., 2020. Logical information model for prediction of reservoir slope stability in water environment control project. In: Bai, X. and Zhou, H. (eds.), Advances in Water Resources, Environmental Protection, and Sustainable Development. Journal of Coastal Research, Special Issue No. 115, pp. 587-592. Coconut Creek (Florida), ISSN 0749-0208.The complex structure of the bank slope in the reservoir area is combined with the continuous undercut of the river to transform the side slope of the bank slope, which poses a certain threat to its stability. Water environment Treatment Engineering the actual data of typical slope collapse and deformation of reservoir are used as the basis, and a new quantitative theory method, logical information method, is adopted, which realizes higher accuracy by establishing logical information model and fuzzy logic expansion of the model. Through the prediction of the stability of the shoreline slope of the whole reservoir area, the stability of the natural and post-water rainstorm is statistically different. It is best to carry on the experimental analysis to the model, the result shows: the natural condition subordinate the potentially unstable shore section is very few, the vast majority is basically stable. In the case of heavy rains after water storage, the proportion of unstable shore segments rose to 9.4%, and the stable shoreline fell to 19.2%. The results show that the logic information model has a certain guiding effect on the prediction of the stability of reservoir bank slope of water Environment control project.

Impact of land use changes on forest catchment area in Pergau Lake, Kelantan

The Pergau lake basin is a man-made water catchment area comprise of 460 hectares due to the construction of hydroelectric dams in Pergau. It is located about 125 km southwest of Kota Bharu in the Jeli district in Kelantan and managed by Tenaga Nasional Berhad. The lake is rich in natural resources and the forest in the basin acts as a reservoir through water absorption and storage. Forests within the area catchments and basins can control soil erosion and erosion of river banks as well slope collapse is one of the sources of risk floods in terms of damage to property and infrastructure such as bridges and road. However, rapid population growth and urbanisation induced the pressure from human activities have been expanded into the forest catchment area. Therefore this study was conducted in the Pergau Lake (Dam) to safeguard their importance for socio-economic, well-being, ecotourism potential and sustaining its biodiversity. This study aims to predict the land use changes in the study area for 2035, parameterised with satellite images in 1988, 2003 and 2018 and the physical parameter such as slope, road, elevation, distance from built up area, green space edge and waterbody. The integrated approach of remote sensing, Geographical Information System (GIS) and Land Change Modeler-Markov Change Model were used to analyze the changes and their spatial pattern. The results showed that between 1994 and 2004, and between 2004 and 2014 the forest landscape in the Pergau Lake were decreased due to the development of the built-up area. Thus, the results will hopefully take into consideration for land use planning and forest protection for sustainable management planning of the forest catchment area. It is indicated that the spatial effect of green space is influenced by the historical spatial changes, implementation of the previous master planning efforts and uncontrolled land use expansion. This study is designed to provide the novel integrated approach for predicting landscape changes for the forest catchment area to provide the initial guideline for sustainable planning and management of forest catchment area.

Experimental Study on Humidity Structure and p-value of Undisturbed Loess in High-risk Slope

A long-term dry-wet cycle will cause changes in the internal structure of the loess, which will affect its permeability coefficient and slope properties. In this paper, through the dry-wet cycle test, the changes of permeability coefficient P value, porosity and dry density of undisturbed loess and remodelled loess under the action of dry-wet cycle are studied. Under the condition of dry-wet cycle, the permeability coefficient of undisturbed loess in high-risk slope decreases, and the permeability coefficient of remoulded loess increases. Remoulding the original loess of high-risk slopes due to soil erosion is more likely to cause gullies and internal erosion, accelerating the occurrence of original loess landslides and collapse of high-risk slopes.

Integrated Field Surveying and Land Surface Quantitative Analysis to Assess Landslide Proneness in the Conero Promontory Rocky Coast (Italy)

Rock slopes involved in extensive landslide processes are often characterized by complex morphodynamics acting at different scales of space and time, responsible for different evolutionary scenarios. Mass Rock Creep (MRC) is a critical process for long-term geomorphological evolution of slopes and can likewise characterize actively retreating coastal cliffs where, in addition, landslides of different typologies and size superimpose in space and time to marine processes. The rocky coast at the Conero promontory (central Adriatic Sea, Italy) offers a rare opportunity for better understanding the predisposing role of the morphostructural setting on coastal slope instability on a long-time scale. In fact, the area presents several landslides of different typologies and size and state of activity, together with a wide set of landforms and structural features effective for better comprehending the evolution mechanisms of slope instability processes. Different investigation methods were implemented; in particular, traditional geomorphological and structural field surveys were combined with land surface quantitative analysis based on a Digital Elevation Model (DEM) with ground-resolution of 2 m. The results obtained demonstrate that MRC involves the entire coastal slope, which can be zoned in two distinct sectors as a function of a different morphostructural setting responsible for highly differentiated landslide processes. Therefore, at the long-time scale, two different morphodynamic styles can be depicted along the coastal slopes that correspond to specific evolutionary scenarios. The first scenario is characterized by MRC-driven, time-dependent slope processes involving the entire slope, whereas the second one includes force-driven slope processes acting at smaller space–time scales. The Conero promontory case study highlights that the relationships between slope shape and structural setting of the deforming areas are crucial for reaching critical volumes to induce generalized slope collapse as the final stage of the MRC process. The results from this study stress the importance of understanding the role of morphostructures as predisposing conditions for generalized slope failures along rocky coasts involved in MRC. The findings discussed here suggest the importance of the assessment of the slope instability at the long time scale for a better comprehension of the present-day slope dynamics and its major implications for landslide monitoring strategies and the hazard mitigation strategies.

Research on Data Analysis of a Long Slope Wireless Monitoring

Slope collapse is one of the most important hazards faced by most water conservancy projects. Due to the long transmission distance and unstable data transmission of existing monitoring methods, the slope safety analysis and evaluation have a great impact. Based on slope design and safety monitoring, this paper proposes to use wireless acquisition and transmission technology to carry out safety monitoring on long slopes, to further improve the accuracy of data, expand the application scope of slope monitoring. And it has been successfully applied in slope monitoring of a water conservancy project.

Three-dimensional active earth pressure under transient unsaturated flow conditions

The active earth pressure evaluation was typically conducted assuming dry backfills and/or two-dimensional collapse mechanisms. In practice, retained slope collapse usually shows a three-dimensional (3D) feature and soils are usually unsaturated. The present work develops a framework for evaluating the 3D active earth pressure under transient unsaturated flow conditions. The framework is implemented by using the kinematic approach of limit analysis, in conjunction with a closed-form solution for the transient unsaturated flow. Based on a 3D horn-like failure mechanism, the active earth pressure coefficient is determined. Results for three hypothetical soils of fine sand, silt, and clay are calculated. It emerges that the inclusion of 3D effects and unsaturated transient flow leads to a smaller active earth pressure coefficient. The 3D effects are mainly influenced by the width-to-height ratio of walls; several certain cases analyzed in this paper show that the difference in the active earth pressure coefficient with and without considering 3D effects can be as much as about 27% when the width-to-height ratio equates to 2, whereas this difference decreases to about 10% and 5% when the ratio reaches to 5 and 10. The contribution of transient flow is mainly affected by the soil types; considering the unsaturated flow effect in clay can approximately reduce the active earth pressure of 67%, whereas this difference corresponds to 34% and 22% in silt and fine sand. The obtained results can help to quantitatively understand changes in the active earth pressure due to 3D effects and the presence of transient infiltration.

Physical Modeling Test on Deformation and Failure of Rock Slope with New Support System

In order to explore the monitoring and control method of rock slope, indoor physical model testing of collapse control and monitoring were carried out with the example of a rock slope collapse area project in Jietai Temple in Beijing, China, as the prototype. Based on the similarity theory, in this study, a new structural support with Negative Poisson’s Ratio bolt and flexible anchored net was utilized to reinforce the rock slope. Following a graded loading sequence, the collapse failure characteristics and the overall control effect of energy absorption reinforcement measures were explored. The experimental results demonstrated that the entire process of slope collapse presented four distinct stages of failure: fracture generation, fracture propagation, partial collapse, and overall collapse. The full‐field displacement nephogram and the displacement monitoring point of the collapse area indicated that the large deformation and failure of the collapsed surrounding rock were effectively controlled, while the Negative Poisson’s Ratio bolt and the flexible anchored net had good reinforcement effects. The experimental stress record presented that the change of pressure curve was an apparent regularity in the entire process of slope collapse, which reflects the change state of internal force of surrounding rock; it includes the function of monitoring of slope collapse. It was indicated that the Negative Poisson’s Ratio bolt along with the large‐deformation flexible anchored net had good reinforcement monitoring effect on the rock slope collapse disaster.