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Introduction: Nepal has witnessed several instances of slope instability associated with Hydroelectric Projects in the recent decades. Despite this, slope instability tends to receive less attention compared to other hazards. Objectives: The objective of this study is to investigate fourteen hydroelectric projects with the aim of identifying the types and causes of slope failures. Additionally, it seeks to offer a comprehensive understanding of slope stability conditions and challenges encountered during construction at project sites. Methods: To accomplish this, the study employs Key Informant Interviews with Questionnaires to delve into the slope stability concerns within Nepal's hydropower projects. The findings are then validated through an extensive review of pertinent literature. To conduct a thorough assessment of slope stability, the study relies on on-site observations, measurements, investigations, and both in-situ and laboratory tests. Results: It becomes evident that the careful selection of study sites, the application of geotechnical methods, and the establishment of regular monitoring are pivotal for ensuring favorable slope stability outcomes. Conclusion: A majority of respondents concur that cutslope is the primary factor causing slope instability with 44.4% answering affirmatively. An independent t-test reveals there is no significant difference between the variables. Moreover, the correlation which is closed to 1 suggests that perception of respondents are interconnected and tend to vary in a synchronized manner. Participants in the study widely acknowledge numerical modeling methods as a means to overcome the limitations of slope stability studies. [ABSTRACT FROM AUTHOR]

Prvić Island (Kvarner area in the NE channel part of the Adriatic Sea) is a part of the Natura 2000 protected area network. A recent tombolo is located on the SW coast of Prvić Island, and much larger submerged tombolos are located on the shoal towards the south. Both phenomena are unique to the Croatian coast of the Adriatic Sea. The inland part of the tombolo was surveyed using an Unmanned Aerial Vehicle, and a 3D point cloud was created using Structure from Motion with Multi-View Stereo photogrammetry. The body of the talus breccia behind the tombolo has a triangular form. Large collapsed rocky blocks form the cape vertex. This cape is in a state of equilibrium in the present oceanographic conditions but might be eroded due to predicted rises in sea level. The submarine zone was explored using scuba-diving equipment and Remotely Operated Vehicles. A large triangle-shaped shoal consists of flysch. Parallel vertical sandstone layers that look like artificially built walls are more than a hundred metres long. The carbonate breccia is located at the end of the shallow zone. The conditions for the final formation of the submerged shoal were created during the sea level stagnation in the Holocene. [ABSTRACT FROM AUTHOR]

The process of rainwater infiltration into unsaturated multi-layered slopes is complex, making it extremely difficult to accurately predict slope behaviors. The hydrological mechanisms in multi-layered slopes could be significantly influenced by the varying hydraulic characteristics of different soils, thus influencing slope stability. A numerical model based on Hydrus 2D was constructed to investigate the hydrological mechanisms of multi-layered slopes under different slope inclinations and rainfall intensities. The results revealed hydraulic processes in response to rainfall in unsaturated multi-layered slopes, in which layered soils retard the advance of wetting fronts and affect seepage paths in the slope. The results also showed the characteristics of hydraulic parameters, including pore water pressure and moisture content, under different conditions, and explained the crucial factors at play in maintaining slope stability. [ABSTRACT FROM AUTHOR]

Mixed turbidite–contourite depositional systems result from interactions between down‐slope turbidity currents and along‐slope bottom currents, comprising excellent records of past oceanographic currents. Modern and ancient systems have been widely documented along the continental margins of the Atlantic Ocean. Yet, few examples have so far been identified on the North‐west African continental margin, limiting understanding of the sedimentary and palaeoceanographic evolution in this area. This work uses two‐dimensional seismic reflection profiles to report, for the first time, the presence of three giant sediment mounds beneath the headwall region of the Sahara Slide Complex. The sediment mounds are elongated and separated by two broad canyons, showing a north‐west/south‐east orientation that is roughly perpendicular to the continental margin. These mounds are 24 to 37 km long and 12 to 17 km wide, reaching a maximum height of ca 1000 m. Numerous slide scarps are observed within and along the flanks of the mounds, hinting at the occurrence of submarine landslides during their development. Based on their geometries, external shapes, internal seismic architecture and stratigraphic stacking patterns, it is proposed that these sediment mounds comprise down‐slope elongated mounded drifts formed in a mixed turbidite–contourite system during four evolutionary stages: onset, growth, maintenance and burial. The significance of this work is that it demonstrates the gradual transition from a turbidite system to a full mixed turbidite–contourite system to be associated, in the study area, with the establishment of strong ocean currents along north‐west Africa. [ABSTRACT FROM AUTHOR]

A method directly using rainfall records to predict a slope's potential instability is devised. The method consists of three sequential steps: identifying the critical suction stress (pore water pressure when soil is saturated) profile of a given slope, developing a rainfall intensity–duration threshold curve for the slope, and using rainfall record to determine if the threshold is reached (failure occurs) or not (no failure). It innovatively uses a slope's strength parameters and slope angle to develop the critical suction stress (tensile) or compressive pore water pressure profile where, at each depth within the slope, the effective stress reaches the failure state. Hydromechanical numerical modeling is then conducted under various rainfall intensities to identify their corresponding duration for slope failure, thus, the rainfall intensity–duration threshold curve of the slope. Two previously well-documented and studied rainfall-induced slope instability cases; one near the town of Edmonds, Washington State, and the other near the village of Rüdlingen in northern Switzerland are used to validate the method. Excellent predictions of the slope failure depth and timing are demonstrated, indicating the effectiveness of the proposed method. Because the suction stress–based rainfall intensity–duration curve is characteristic of a given slope and it can be determined a priori, the method provides a practical way to conduct real-time rainfall monitoring and predict instability for a specific slope, and a pathway to forecast instability of natural slopes in a region. [ABSTRACT FROM AUTHOR]

The Hasankeyf Antique City contains several historical structures, ancient and new man-made caves. The dolomitic limestone exposed in the area is the main rock, but weak and not durable. The rock is deteriorated under environmental conditions such as wetting–drying and salt crystallization. The area is now partly under reservoir water of Ilısu dam. The aim of this study is to assess geoenvironmental problems of the Hasankeyf Antique City for different environmental conditions and evaluate possible mitigation measures by considering rock properties and archeological values of the site. Field and laboratory studies as well as various slope stability analyses were carried out. This study indicates that there are problems such as erosion and undercutting of the limestone, block failure associated with collapse of the man-made caves, rock weakening due to cyclic environmental conditions, and slope instabilities dominantly in the form of planar failure and rockfall. An engineering fill is constructed to mitigate the effect of harsh environmental conditions and wave effect due to reservoir water. It also works as lateral support for the steep cliffs. Already detached rocks having no archeological values are removed, and a critical block underneath the Small Palace is stabilized. Furthermore, the Small Palace being partly under reservoir level is raised in such a way that the ancient structure is well above the maximum reservoir level. On the other hand, systematic monitoring of the critical historical structures and limestone blocks should be considered to check the long-term behavior of these. [ABSTRACT FROM AUTHOR]

Abstract Introduction Nepal has witnessed several instances of slope instability associated with Hydroelectric Projects in the recent decades. Despite this, slope instability tends to receive less attention compared to other hazards. Objectives The objective of this study is to investigate fourteen hydroelectric projects with the aim of identifying the types and causes of slope failures. Additionally, it seeks to offer a comprehensive understanding of slope stability conditions and challenges encountered during construction at project sites. Methods To accomplish this, the study employs Key Informant Interviews with Questionnaires to delve into the slope stability concerns within Nepal’s hydropower projects. The findings are then validated through an extensive review of pertinent literature. To conduct a thorough assessment of slope stability, the study relies on on-site observations, measurements, investigations, and both in-situ and laboratory tests. Results It becomes evident that the careful selection of study sites, the application of geotechnical methods, and the establishment of regular monitoring are pivotal for ensuring favorable slope stability outcomes. Conclusion A majority of respondents concur that cutslope is the primary factor causing slope instability with 44.4% answering affirmatively. An independent t-test reveals there is no significant difference between the variables. Moreover, the correlation which is closed to 1 suggests that perception of respondents are interconnected and tend to vary in a synchronized manner. Participants in the study widely acknowledge numerical modeling methods as a means to overcome the limitations of slope stability studies.

Backward erosion piping, a soil erosion phenomenon induced by seepage, compromises the stability of water-retaining structures such as dikes. During floods, the seepage in the dike body increases due to high water levels, which directly affects the progression of the piping channel. The formation of the piping channel then impacts the stability of the dike. In this paper, an improved piping model that considers the impact of seepage in the dike body is proposed based on Wewer's model. Specifically, we added a seepage field of the dike body to the original model to account for the impact of dike-body seepage on the evolution of piping. The seepage field of the dike body is solved using Darcy's law and the continuity equation for unsaturated porous media. In addition, this approach also incorporates the coupling effect of seepage stress. The accuracy of the model was verified through comparing the calculated results with the IJkdijk experiment and Wewer's results. The effects of BEP on dike stability were investigated using the proposed improved piping model. The two major conclusions of the study are that (1) the incorporation of unsaturated seepage enhanced the performance of the piping model, allowing it to more accurately simulate the development of pipe length and the changing of pore pressure; and (2) the formation of the pipe impacted dike stability, leading to a substantial reduction in the safety factor of the dike slope. [ABSTRACT FROM AUTHOR]

This paper presents the results of a geotechnical investigation regarding the slope stability in a pit lake, emphasizing the impact of water level variations. Advanced analysis techniques were utilized for this study. The research was performed by using fully coupled flow-deformation analyses. For the fully coupled approach, Bishop's effective-stress equation was used, and for the description of soil hydraulic behavior, the Van Genuchten's model was applied. The analysis of slope stability associated with reservoir water level changes revealed that the slope tended to become unstable as the water level decreased; the stability factor was negatively related to the rate of water level reduction. Concerning the water level fluctuations, the analyses revealed that the soil mass seemed to become less stable as the rate of water level change increased. Under a specific range of rates of water level variation, the safety factor became higher as the number of fluctuations increased. Additionally, the simulation results concerning the water level rising indicate that the pressure due to the external water level acts on the slope surface with a positive impact on the stability factor. The results obtained reflect the effects under a specific site condition, but they can be used as a reference for evaluating slope stability in a pit lake design. [ABSTRACT FROM AUTHOR]

There are many rich water open-pit mines in China and the water inflow is large, if the mine groundwater or slope is not properly treated, it will face the dilemma of “water disaster, difficult strengthening of slope, and difficult mining of mines”. Open pit mines in China have developed a variety of groundwater control technologies such as vertical hydrophobic holes, horizontal hydrophobic holes, large diameter hydrophobic holes under the pit and well group hydrophobic and other pumping and draining methods, drainage alleys at the bottom of the pit, pit precipitation and radiation well draining, as well as water interception curtains and water curtains such as borehole slurry curtains, concrete diaphragm wall curtains, pile-row curtains and impermeable membrane curtains to solve the flooding and slope instability encountered in open pit mines. The effects of groundwater control techniques on groundwater level, changes in geotechnical properties of end-slope, changes in slope stress and slope stability coefficients in open pit mines were studied, and the effects of groundwater level lifting on slope stability under the action of water curtain were analyzed. The research results show that draining or de-watering the groundwater in the open pit can effectively reduce the depth of the groundwater, reduce the water content of the slope geotechnical body, improve the cohesion and internal friction angle of the slope geotechnical body, reduce the hydrostatic pressure and horizontal thrust of the slope body, and improve the overall stability coefficient of the slope; however, de-watering a large amount of groundwater can cause waste of water resources and pollution. The water cut-off curtain can solve the problems of too large a drop in groundwater level, huge volume of water drainage, waste of water resources and pollution caused by water drainage and precipitation. Under the action of water interception curtain, the water level on the outside of water interception curtain in the open pit mine keeps rising, which causes the water content of geotechnical body on the outside of water interception curtain to increase, the cohesion and internal friction angle to decrease, and the hydrostatic pressure and horizontal thrust of slope body to increase; while the water content of geotechnical body on the inside of water interception curtain decreases, the cohesion and internal friction angle to increase, and the hydrostatic pressure and horizontal thrust of slope body to decrease, which causes the stability coefficient of slope in open pit coal mine to slightly decreased. The slope stability coefficient is still within the safe range, and it also protects the groundwater resources of the open pit mine.

The Ethiopian economy is primarily dependent on agriculture, making the construction of water harvesting facilities, such as dams, crucial for improving the productivity of this sector. The ongoing construction of the Gololcha dam on the Kurkura River located in Eastern Ethiopia aims to enhance irrigation schemes in the region. However, the dam site's complex geological and structural conditions pose challenges related to leakage and slope instability. Hence, this study focuses on addressing the abutment slope stability and leakage condition of this dam. This study employed kinematic analysis and the Limit Equilibrium Method (LEM) to assess slope stability. Additionally, engineering geological mapping, discontinuity surveys, seismic refraction tomography (SRT), and in-situ permeability testing were used to evaluate the leakage condition of the dam site. Notably, the permeability and SRT survey results identified potential leakage zones to the depth of 35, 30, and 35 m at the left, right, and central foundations of the dam, respectively. The kinematic method revealed one planar and two wedge modes of failure in the slope section covered by slightly weathered and fractured basalt rock at the right abutment. Further stability analysis of these two modes of failures via LEM analysis indicated slope instability under saturated conditions, emphasizing the role of pore water pressure. Furthermore, LEM modeling was directly utilized using the Slide 6.0 software to analyze the slope stability condition of the left abutment of the dam. This modeling also uncovered instability under saturated conditions. Based on the study findings, this study recommended curtain grouting to address potential leakage, as well as slope flattening and removing unstable rock wedges and loose material to stabilize unstable slope sections.

Slope instability is a common type of damage in embankment dams. Analyzing its microstructural changes during water transport is beneficial to identify the critical damage point in more detail. To this end, we closely link both diffused water molecule and damaged concrete. On the basis of the original research on fractal theory, the fractal permeability model for the pore system is established. At the same time, considering the pore structure characteristics of concrete, the models for fluid–solid coupling inside and outside the embankment are established in this work. The simulated results and experimental data agree well, thus verifying the correctness of the proposed models. The changes of concrete pore structures under different water pressure and different initial porosities are simulated by numerical methods. The results show that: (1) with the increase of the safety factor, the slope of the embankment begins to be damaged at the critical point and then completely destabilized; (2) with the increase of the pressure head, the change of the fractal dimension of the embankment's porosity from the top to the bottom changes from linear to nonlinear. (3) The initial porosity of concrete is proportional to the evolution of concrete pore structure. From a technical point of view, this study can contribute the effective technical guidance for related professional practitioners in the analysis of embankment slope stability from a microscopic point of view. [ABSTRACT FROM AUTHOR]

Landsliding and slope instability pose significant risks to human settlements and infrastructure. This study aims to develop a landslide susceptibility map for the mountainous regions of Tehran province, Iran. The rock engineering approach was employed at a regional scale, utilizing a database of regional landslides. The semi‐quantitative Rock Engineering System method was applied, considering 10 conditioning factors. The model was validated using historical landslide data, showing strong correlation. The majority of landslides occurred within medium and high susceptibility zones. Geological units, particularly the Karaj Formation's claystone layers, displayed a clear association with landslide susceptibility. The rock engineering approach yielded a highly accurate susceptibility map. Findings can inform future territorial planning in the area. [ABSTRACT FROM AUTHOR]

Rainfall is the main factor of slope instability. In order to study the evolution and migration law of slope humidity under rain infiltration under different rainfall intensities. The field tests of slope instability under different rainfall intensities of 75 mm/h, 125 mm/ h, 150 mm/ h and 175 mm/ h were conducted, and the progressive failure characteristics of slope were studied according to the water-time-time and displacement-time curves, and the rainfall time and rainfall threshold of slope instability were proposed. According to the rainfall intensity, the slope instability failure can be divided into four modes: shallow local slide, shallow integral slide and collapse, deep local slide and deep integral slide. The deformation and instability of slopes are mainly located at the foot of the slope, followed by the middle of the slope, and the slope top is the smallest. It last 18 ~ 20 min for the deep slope to slide from significant deformation to instability, while the shallow slope to slide lasts 2 ~135 min. Slope instability and soil boundary water content can be significantly correlated with the failure process of slope instability. When the shallow soil water content of slope rises to 42% ~45%, the slope begins to show signs of instability such as cracking and creep deformation. When the soil moisture content rises to 47% ~ 50%, the soil on the slope begins to collapse and landslides and collapses quickly. [ABSTRACT FROM AUTHOR]

The research interest in multi-hazard chains lies in the comprehension of how various hazards, such as debris flows, floods, and landslides, can interact and amplify one another, resulting in cascading or interconnected hazards. On 17 June 2020, at approximately 3:20 a.m., a debris flow occurred in Meilong gully (MLG), located in Banshanmen Town, Danba County, in southwest China's Sichuan Province. The debris flow had a discharge volume of approximately 40 x 104 m3 and rushed out to block the Xiaojinchuan (XJC) river, subsequently forming a barrier lake. This event ultimately induced a hazard chain that included heavy rainfall, debris flow, landslides, the formation of a barrier lake, and an outburst flood. The impact of this chain resulted in the displacement of 48 households and affected 175 individuals. Furthermore, it led to the destruction of an 18 km section of National Highway G350, stretching from Xiaojin to Danba County, causing economic losses estimated at 65 million yuan. The objective of this study is to analyze the factors leading to the formation of this hazard chain, elucidate its triggering mechanisms, and provide insights for urban areas in the western mountainous region of Sichuan to prevent similar dam-break type debris flow hazard chains. The research findings, derived from field investigations, remote sensing imagery analysis, and parameter calculations, indicate that prior seismic disturbances and multiple dry-wet cycle events increased the volume of loose solid materials within the MLG watershed. Subsequently, heavy rainfall triggered the initiation of the debris flow in MLG. The cascading dam-break, resulting from three unstable slopes and boulders within the channel, amplified the scale of the hazard chain, leading to a significant amount of solid material rushing into the XJC river, thus creating a dam that constricted the river channel. With the intensification of river scouring, the reactivation and destabilization of the Aniangzhai (ANZ) paleolandslide occurred, ultimately leading to the breach of the dam and the formation of an outburst flood. The research comprehensively and profoundly reveals the causal mechanism of the MLG hazard chain, and proposes measures to disrupt the chain at various stages, which can aid in enhancing monitoring, early warning, forecasting systems, and identifying key directions for ecological environmental protection in urban areas within the western mountainous region of Sichuan. Additionally, it could also serve as a reference for mountainous urban areas such as the Tianshan, Alps, Rocky Mountains, and Andes, among others. [ABSTRACT FROM AUTHOR]

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Recent studies reveal an ongoing worldwide increase in a number of slope instability manifestations and their positive correlation with human activity. The latter involves construction activity as one of the most common trigger or susceptibility raising factors. In this study, we conduct a detailed analysis of an extensive and rapid transformation of a forest-covered mountain landscape and its response. The study area is a mountain sport cluster of the Winter Olympic Games-2014, which developed from scratch to a large tourist resort in just a few years. A time-series of aerospace images were used for a comprehensive mapping of the land cover changes and associated development of slope instabilities over 15 years, from a "pre-construction era" until now. We identify widespread deforestation and the land cover changes in upper chains of the fluvial systems to be the key drivers of the enhanced multiplication and intensification of the slope hazard processes. Completion of the active construction phase leads relatively quickly to a gradual natural stabilisation of the slope-located processes. However, the stream-located processes need several decades to regain a balance, because the increasing energy of small watercourses, due to growth of surface runoff coefficient, led to the transformation of longitudinal profiles of their channels. The obtained results provide a refined look at the anthropogenic influence on the slope instability occurrence and their short-time evolution in a mountain forest landscape. We also discuss the prospective course of events for this resort. [ABSTRACT FROM AUTHOR]

Land degradation in the form of mass movement is a major challenge in the humid tropics, where intense rainfall and tropical cyclones are common. Rainfall increases soil moisture content, which often acts as a triggering factor for mass movement events, particularly in clay soils with expansive minerals, where moisture changes impact structural integrity. Growing evidence suggests that Nature-based Solutions (NbS) can regulate soil moisture levels, which can assist in maintaining cohesion and hence reduce slope instability. This paper examines soil moisture changes due to Coconut Matting (CM), Coconut Matting-Natural Vegetation Hybrid (CMNV), Natural Vegetation (NV), and Vetiver grass (VET) and discusses moisture content regulation as it relates to slope stability, with a particular focus on expansive clays. Soil moisture trends were measured for 90 days at four depths (20 cm, 40 cm, 60 cm, and 100 cm) using soil moisture loggers, while precipitation levels were monitored using a rain gauge. GLM ANOVA analysis showed a significant depth*treatment interaction (P < 0.05) on soil moisture. The Vetiver grass treatment had the lowest soil moisture levels, with a (27.62 %) reduction compared to the control (bare plot). The CMNV treatment had the second-greatest-% soil moisture reduction (7.68 %). Contrastingly, CM and NV resulted in limited moisture reduction (1.99 %) and (0.73 %) respectively. The role of Vetiver grass was therefore highlighted in mitigating water saturation towards preventing potential slope instability.

Traffic along the Mediterranean ring road in northern Morocco is permanently disrupted by ground movements. Several sections of the road are not practicable during each rainy period. The slopes and hillsides that were excavated and remodelled during the construction of the roadway have become unstable and are subject to important landslides. In our present study, we will focus on the section of road located at kilometre point PK 176+800 between Oued Laou and Jebha City. The aim of this study is to evaluate the degree of instability of the studied slope, in the present and also predict it in the future. In situ and laboratory geotechnical tests and geophysical investigations based on Electrical Tomography were carried out to complement the geomatic analyses performed by the research team. The results obtained testify to the effectiveness of the methodology adopted and confirm the threatening instability of the slope studied, in particularly at landslide area.

Prvić Island (Kvarner area in the NE channel part of the Adriatic Sea) is a part of the Natura 2000 protected area network. A recent tombolo is located on the SW coast of Prvić Island, and much larger submerged tombolos are located on the shoal towards the south. Both phenomena are unique to the Croatian coast of the Adriatic Sea. The inland part of the tombolo was surveyed using an Unmanned Aerial Vehicle, and a 3D point cloud was created using Structure from Motion with Multi-View Stereo photogrammetry. The body of the talus breccia behind the tombolo has a triangular form. Large collapsed rocky blocks form the cape vertex. This cape is in a state of equilibrium in the present oceanographic conditions but might be eroded due to predicted rises in sea level. The submarine zone was explored using scuba-diving equipment and Remotely Operated Vehicles. A large triangle-shaped shoal consists of flysch. Parallel vertical sandstone layers that look like artificially built walls are more than a hundred metres long. The carbonate breccia is located at the end of the shallow zone. The conditions for the final formation of the submerged shoal were created during the sea level stagnation in the Holocene.

The process of rainwater infiltration into unsaturated multi-layered slopes is complex, making it extremely difficult to accurately predict slope behaviors. The hydrological mechanisms in multi-layered slopes could be significantly influenced by the varying hydraulic characteristics of different soils, thus influencing slope stability. A numerical model based on Hydrus 2D was constructed to investigate the hydrological mechanisms of multi-layered slopes under different slope inclinations and rainfall intensities. The results revealed hydraulic processes in response to rainfall in unsaturated multi-layered slopes, in which layered soils retard the advance of wetting fronts and affect seepage paths in the slope. The results also showed the characteristics of hydraulic parameters, including pore water pressure and moisture content, under different conditions, and explained the crucial factors at play in maintaining slope stability.

The medieval town of San Leo and its fortress have been classified as a "settlement to be consolidated", following the Italian law. They rise on a rocky, steep cliff that is prone to failure, as well as the entire area surrounding the cliff is subject to slope instability phenomena. Over the past seventy years, a series of consolidation works have been conducted on the rock walls. These interventions focused mainly on the south face, where the town and its access road are located, and on the east face, particularly in the area where the fortress is situated. Since the 1980s, efforts to reduce the risk have also focused on the base of the cliff with the aim to prevent its erosion and undermining. The latter is considered the cause of major rock failures, such as the landslide that occurred in 2014. Despite past interventions, however, landslide risk in the San Leo cliff still remains high. The slope failure of 2014 marks a dividing line: after that a comprehensive multidisciplinary study was started. The study involved different investigation and monitoring techniques in order to understand, prevent, and reduce landslide risk. The in-depth knowledge gained through this study was crucial in managing the emergency after the collapse, providing the essential elements for defining risk scenarios and for planning and designing interventions to reduce risk after the emergency phase. These interventions were carried out on the north face of the cliff, where the main landslide occurred in 2014, but also the east and south faces. [ABSTRACT FROM AUTHOR]

The traffic along the Mediterranean ring road in northern Morocco is permanently disrupted by ground movements. Several sections of the road are not available during the rainy period. The slopes and hillsides that were excavated and remodeled during the construction of the roadway have become unstable and are subject to important landslides. In the present study, focused on the section of road located at kilometer point PK 176+800 between Oued Laou and Jebha City. The aim of this study was to evaluate the degree of instability of the studied slope, in the present and to predict it in the future. In situ and laboratory geotechnical tests as well as the geophysical investigations based on Electrical Tomography were carried out to complement the geomatic analyses performed by the research team. The results obtained testify to the effectiveness of the methodology adopted and confirm the threatening instability of the slope studied, in particularly at landslide area. [ABSTRACT FROM AUTHOR]

The purpose of this study is to map and geographically locate areas with a high probability of natural events occurring such as "rockfall". In this context, a multi-method approach is proposed to characterize and evaluate the potential vulnerability of an unstable ground as well as rockfall risk, through morpho-tectonic, geological, and morphometric analysis integrated into a geographic information system (GIS). Several parameters such as slope, lithology, lineaments, morphology, land use, and rainfall have been integrated and indexed in a geographic information system to be able to develop the rockfall risk map that allowed us to detect and geographically delimit the unstable areas in the Korbous cliff. The studied area presents a contrasted territory, from both morphological and geological points of view. The steep slopes' rockfalls are quite frequent and constitute a potential risk to infrastructure and habitats at the bottom of slopes such as Korbous village, Ain Oktor, and MC 128 road. The proposed rockfall risk map, in this study, would serve as a guide and decision-support tool for the choice of preventive measures for reducing disaster risk (RDR). [ABSTRACT FROM AUTHOR]

Long-runout landslides occur frequently in the sandstone and mudstone mountainous areas in southwestern China under heavy rainfall conditions. This has been a key issue in the field of disaster prevention and reduction. Considering the Niuerwan landslide in Wulong, Chongqing, on 13 July 2020, as an example, we employed technical methodologies, including unmanned aerial vehicle (UAV) images, field investigation, geological condition analysis (including geomorphology and topography, stratigraphic structure and formation lithology, etc.), interferometric synthetic aperture radar (InSAR) monitoring and Particle Flow Code 3D (PFC3D) simulations to study failure mechanism and a long-runout motion model of flow-like landslides induced by the heavy rainfall. The results showed that (1) the large differences between the upper and lower strata are the root cause of the instability and long-runout fluidization movement; (2) heavy rainfall is the key driving factor of slope instability and deep-seated landslides, leading to long-distance movement of the upper saturated residual soil; (3) the long-runout fluidization model of bedding landslides is mainly divided into the overall sliding in the lower layer, the mixing of coarse and fine particles in the middle layer, and saturation fluidization in the upper layer; and (4) the long-runout fluidization process of bedding landslides is composed of three stages: overall instability, mixed acceleration, and fluidization accumulation. In view of these findings, in the risk evaluation and prediction of long-runout fluidization landslides in sandstone and mudstone mountainous areas, this particular disaster model can be used to provide quantitative references for disaster prevention and mitigation. [ABSTRACT FROM AUTHOR]

Cultural heritage sites can be affected by landslides, often causing damage to their integrity, value, and accessibility. Several studies worldwide were focused on the assessment of the potential threats that landslides can pose to the preservation of cultural heritage sites. This article aims to review landslide studies at cultural heritage sites worldwide, analyzing the publications’ temporal distribution, selected methods, geographical and climate contexts, and investigated landslide types. We analyzed a database of 331 publications from 2000 to 2023 in study areas distributed across 47 countries, compiled through systematic queries of the Web of Science and Scopus catalogs. The results show an increase in the number of publications from 2012 onwards, with most studies performing landslide susceptibility analyses on cultural heritage sites. The majority of the studies deployed a geomorphological approach address slope instability mechanisms that threaten site integrity, with a significant number of publications presenting model-based, multidisciplinary and engineering geological approaches. Europe, North America, and Asia and the Pacific concentrate the majority of studies, with Italy and China having the highest number of case studies. The threats to cultural heritage sites located in Latin America and the Caribbean, and Africa are the least studied. Block slides, earth slides, and rock falls are the most studied processes, with fewer studies dealing with other landslide types.

Backward erosion piping, a soil erosion phenomenon induced by seepage, compromises the stability of water-retaining structures such as dikes. During floods, the seepage in the dike body increases due to high water levels, which directly affects the progression of the piping channel. The formation of the piping channel then impacts the stability of the dike. In this paper, an improved piping model that considers the impact of seepage in the dike body is proposed based on Wewer’s model. Specifically, we added a seepage field of the dike body to the original model to account for the impact of dike-body seepage on the evolution of piping. The seepage field of the dike body is solved using Darcy’s law and the continuity equation for unsaturated porous media. In addition, this approach also incorporates the coupling effect of seepage stress. The accuracy of the model was verified through comparing the calculated results with the IJkdijk experiment and Wewer’s results. The effects of BEP on dike stability were investigated using the proposed improved piping model. The two major conclusions of the study are that (1) the incorporation of unsaturated seepage enhanced the performance of the piping model, allowing it to more accurately simulate the development of pipe length and the changing of pore pressure; and (2) the formation of the pipe impacted dike stability, leading to a substantial reduction in the safety factor of the dike slope.

This paper presents the results of a geotechnical investigation regarding the slope stability in a pit lake, emphasizing the impact of water level variations. Advanced analysis techniques were utilized for this study. The research was performed by using fully coupled flow-deformation analyses. For the fully coupled approach, Bishop’s effective-stress equation was used, and for the description of soil hydraulic behavior, the Van Genuchten’s model was applied. The analysis of slope stability associated with reservoir water level changes revealed that the slope tended to become unstable as the water level decreased; the stability factor was negatively related to the rate of water level reduction. Concerning the water level fluctuations, the analyses revealed that the soil mass seemed to become less stable as the rate of water level change increased. Under a specific range of rates of water level variation, the safety factor became higher as the number of fluctuations increased. Additionally, the simulation results concerning the water level rising indicate that the pressure due to the external water level acts on the slope surface with a positive impact on the stability factor. The results obtained reflect the effects under a specific site condition, but they can be used as a reference for evaluating slope stability in a pit lake design.

The slope has the typical deformation failure and instability characteristics under the interaction of natural and human factors which has been given a lot of attention in geotechnical and mining engineering. During highwall mining, in particular, deformation evolution characteristics and failure mode are more complex under dual influence of open pit mine and underground mine. Physical modelling is an important means to study the characteristics and behavior of deformation and evolution of various types of rock and soil mass, and it is also an important supplement to the field study of large-scale rock and soil mass. It is widely used in mines and geotechnical engineering. The determination of the material used for physical modeling is the foundation and key links of research. Therefore, the article firstly selected river sand/aggregate, lime and gypsum/cemented material as the experimental materials through the relevant literature review and based on the principle of economic and convenience, and adopted two proportioning schemes to make standard specimens. The uniaxial compression test was carried out to compare and analyze the strength of the original rock, and it was determined that the scheme 2 could be used as the research scaling number of the physical modelling; Secondly, on the basis of determining the material proportion, the physical and structural model of highwall mining is established, and the analysis shows that the evolution characteristics of slope deformation and failure in the process of highwall mining can be divided into superficial transformation stage, structural transformation stage and aging deformation stage, the deformed and damaged rock mass can be divided into “vertical three zones”, namely caved zone, fractured zone and continuous bending zone. According to the length of the panel, the coal seam can be divided into three stages: initial stage, middle stage and final stage. The lower coal seam can be divided into two stages: the initial stage and the final stage. The evolution of the slope rock mass due to the extraction of the upper coal seam to the stopping line is characterized by the formation of subsidence faded areas along the center of the goaf to both sides, and finally a symmetrical distribution of semi-“pyramid” shape is formed. The rock mass that is deformed and damaged due to the extraction of the lower seam to the mining stop line is in a semi-curve-like shape; Finally, based on the analysis of physical modelling and field monitoring, it is concluded that when the upper coal seam of the highwall coal seam is mined to about 120 m, the slope shows a slight instability. When the lower coal seam is mined to about 120 m, the goaf between the upper and lower coal seams is connected, and the instability is intensified until the mining reaches the stopping line. In the upper part of the slope, 1400 step forms a local collapse instability zone pointing to the open-pit, while the rest of the step are anti-dip instability pointing to the goaf.

The research interest in multi-hazard chains lies in the comprehension of how various hazards, such as debris flows, floods, and landslides, can interact and amplify one another, resulting in cascading or interconnected hazards. On 17 June 2020, at approximately 3:20 a.m., a debris flow occurred in Meilong gully (MLG), located in Banshanmen Town, Danba County, in southwest China’s Sichuan Province. The debris flow had a discharge volume of approximately 40 × 104 m3 and rushed out to block the Xiaojinchuan (XJC) river, subsequently forming a barrier lake. This event ultimately induced a hazard chain that included heavy rainfall, debris flow, landslides, the formation of a barrier lake, and an outburst flood. The impact of this chain resulted in the displacement of 48 households and affected 175 individuals. Furthermore, it led to the destruction of an 18 km section of National Highway G350, stretching from Xiaojin to Danba County, causing economic losses estimated at 65 million yuan. The objective of this study is to analyze the factors leading to the formation of this hazard chain, elucidate its triggering mechanisms, and provide insights for urban areas in the western mountainous region of Sichuan to prevent similar dam-break type debris flow hazard chains. The research findings, derived from field investigations, remote sensing imagery analysis, and parameter calculations, indicate that prior seismic disturbances and multiple dry-wet cycle events increased the volume of loose solid materials within the MLG watershed. Subsequently, heavy rainfall triggered the initiation of the debris flow in MLG. The cascading dam-break, resulting from three unstable slopes and boulders within the channel, amplified the scale of the hazard chain, leading to a significant amount of solid material rushing into the XJC river, thus creating a dam that constricted the river channel. With the intensification of river scouring, the reactivation and destabilization of the Aniangzhai (ANZ) paleolandslide occurred, ultimately leading to the breach of the dam and the formation of an outburst flood. The research comprehensively and profoundly reveals the causal mechanism of the MLG hazard chain, and proposes measures to disrupt the chain at various stages, which can aid in enhancing monitoring, early warning, forecasting systems, and identifying key directions for ecological environmental protection in urban areas within the western mountainous region of Sichuan. Additionally, it could also serve as a reference for mountainous urban areas such as the Tianshan, Alps, Rocky Mountains, and Andes, among others.

Cultural heritage sites can be affected by landslides, often causing damage to their integrity, value, and accessibility. Several studies worldwide were focused on the assessment of the potential threats that landslides can pose to the preservation of cultural heritage sites. This article aims to review landslide studies at cultural heritage sites worldwide, analyzing the publications' temporal distribution, selected methods, geographical and climate contexts, and investigated landslide types. We analyzed a database of 331 publications from 2000 to 2023 in study areas distributed across 47 countries, compiled through systematic queries of the Web of Science and Scopus catalogs. The results show an increase in the number of publications from 2012 onwards, with most studies performing landslide susceptibility analyses on cultural heritage sites. The majority of the studies deployed a geomorphological approach address slope instability mechanisms that threaten site integrity, with a significant number of publications presenting model-based, multidisciplinary and engineering geological approaches. Europe, North America, and Asia and the Pacific concentrate the majority of studies, with Italy and China having the highest number of case studies. The threats to cultural heritage sites located in Latin America and the Caribbean, and Africa are the least studied. Block slides, earth slides, and rock falls are the most studied processes, with fewer studies dealing with other landslide types. [ABSTRACT FROM AUTHOR]

• The dual cover system, weight function and displacement function of 3D-NMM are proposed. • The element stiffness matrix, inertial force matrix, loading point matrix, etc. are derived. • The contact detection algorithm is realized based on the cover-based contact theory. • The accuracy of the developed code is verified through two continuous and discontinuous models. • The robustness of the developed code is further verified through the low velocity impacting model. Based on the mathematical grid of 4-node tetrahedral finite element form, the dual cover system, weight function and displacement function of three-dimensional numerical manifold method (3D-NMM) are proposed. The derivation process of element stiffness matrix, inertial force matrix, loading point matrix, etc. are systematically demonstrated in the present work. Based on the cover-based contact theory, the contact detection algorithm among discrete 3D blocks is realized, and the 3D manifold framework is programmed. The accuracy of the developed code is firstly calibrated through two continuum deformation analysis: cantilever beam bending model and axial tensile model of thin plate with circular hole. Then it is applied to three complex discontinuous instability simulation (SHPB, brick wall structure and cliff slope) to verify the effectiveness and accuracy of the proposed contact algorithm. The classic Steven low velocity impact process is also simulated, and the deformation and failure of polymer bonded composites (PBC) are predicted, which further verifies the feasibility and robustness of the developed code in dealing with dynamic impact problems. [ABSTRACT FROM AUTHOR]

Flood season embankment due to long-term high water immersion environment creates situations where its soil properties will deteriorate, quickly triggering bank slope instability and other dangerous situations. In order to study embankment slope soil in the disintegration and permeability characteristics under the long-term water immersion process, disintegration tests and variable head infiltration tests were carried out on embankment-disturbed clays in Jiangxinzhou, Nanjing, Jiangsu Province, China. The results showed that the disintegration rate decreased with increasing dry density. Moreover, the samples gained weight quickly when the water content was low. Moreover, there is a threshold water content of around 20%, and it is assumed that the disintegration pattern of the soil may be significantly different depending on the optimum moisture content. The effect of moisture content on the disintegration of the samples was more significant. There were three main typical disintegration modes of the samples. The primary influencing factors resulting in the various disintegration patterns are the soil matrix suction, the change in consistency following water immersion, and the water membrane on the surface of the clay particles. The coefficient of permeability decreases with increasing dry density, and the variation of the coefficient of permeability with dry density coincides with the exponential function relationship. Long-term immersion conditions will change the permeability of the soil. An electron microscope test of immersed and unimmersed samples shows that the internal structure change is an essential factor affecting the permeability. After water immersion, with the dissolution of cementing material between soil particles, the particles move to fill the intergranular pore space so that the permeability coefficient decreases. [ABSTRACT FROM AUTHOR]

Geyser geothermal fields are scenic volcanic landforms that often contain tens to hundreds of thermal spot vents that erupt boiling water or contain bubbling mud pools. The fields are potentially hazardous sites due to boiling water temperatures and changes in vent locations and eruption dynamics, which are poorly understood. Here we report on the rapid and profound changes that can affect such a geyser field and ultimately lead to a dangerous, unanticipated eruption. We studied the Geyser Valley, Kamchatka Peninsula, which is a field of geysers and other thermal features and boiling pools. Using high-resolution tri-stereo satellite data and unmanned aerial systems (UAS) with optical and thermal infrared cameras in 2018 and 2019, we were able to identify a newly emerging explosion site. Structure-from-motion analysis of data acquired before and after the explosion reveals morphological and thermal details of the new vent. The explosion site produced an aureole zone of more than 150 m3 of explosively redeposited gravel and clay, a slightly elliptical crater with a diameter of 7.5 m and a crater rim 0.30 m high. However, comparison with archives of photogrammetric data suggests that this site was thermally active years earlier and contained a crater that was obscured and covered by landslides and river sediments. The results allow us to develop a conceptual model and highlight the hazard potential of thermal features buried by landslides and clastic deposits. Sudden explosions may occur at similar sites elsewhere, highlighting the need for careful assessment and monitoring of geomorphological and hydrological changes at geyser sites in other regions.

Key points Relationship between soil electrical resistivity and hydraulic conductivity were examined for assessment of lithology inducing shallow-landslide. Soil electrical resistivity delineated a boundary between two contrasting resistive and conductive lithologies at 4 m depth. Strong correlation ranged between R2 = 0.9153 to 0.9702 were observed between soil resistivity and hydraulic conductivity for the soil samples examined. The conductive lithology with low hydraulic conductivity below 4 m depth was responsible for the occurrences of the shallow-landslides.

During flood season, embankments are often submerged in high water levels for extended periods, leading to deterioration in their soil mechanics performance and increasing the risk of slope instability and other hazards. In order to investigate the changes in mechanical properties of embankment slopes during long-term water immersion, direct shear tests were conducted. Scanning electron microscopy, chemical composition analysis, and laser particle size analysis were conducted on samples taken at different immersion periods. Clay samples were taken from the embankments at Jiangxinzhou in Nanjing, Jiangsu Province, China. Results showed the shear strength of the soil gradually decreases with the increase of immersion time, while the cohesive force and internal friction angle gradually decrease as well. This suggests that immersion has a softening effect on the shear strength of the soil. As the immersion time increases, the colloidal particles (soluble salt) rapidly dissolves, the microstructure of the soil is destroyed, and sticky particles increases, resulting in a change in the shear strength of the soil. The research results provide a basis for flood control and prevention of embankments immersed in high water levels for long periods during the flood season.

The relationships between hillslope and fluvial processes were studied in a mountainous area of the Northern Apennines (Italy) where intermittent landslide activity has interacted for a long time with river morphodynamics. The aim of the study was to analyse such relationships in two study sites of the Scoltenna catchment. The sites were analysed in detail and monitored through time. A long-term analysis was carried out based on multitemporal photointerpretation of aerial photos. Slope morphological changes and land use modifications since 1954 were detected and compared with the evolution of the channel morphology. A short-term analysis was also performed based on two monitoring campaigns accomplished in 2021 and 2022 in order to detect possible slope displacements and channel-bed-level changes. The techniques used are global navigation satellite systems and drone photogrammetry accompanied by geomorphological surveys and mapping. The multitemporal data collected allowed us to characterise slope surface deformations and quantify morphological changes. The combination of various techniques of remote and proximal sensing proved to be a useful tool for the analysis of the surface deformations and for the investigation of the interaction between slope and fluvial dynamics, showing the important role of fluvial processes in the remobilisation of the landslide toe causing the displacement of a significant volume of sediment into the stream. [ABSTRACT FROM AUTHOR]

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This study analyses the causes and consequences of slope instability around the historical Himalayan town of Joshimath, Uttarakhand, India. The town is in the Higher Himalaya near the Main Central Thrust. The lithology constitutes fissile, shattered and sheared gneiss. Consequently, the slopes are prone to land subsidence and mass wasting. In the last few decades rise in population has led to a surge of infrastructure development, thus causing immense pressure on the finite resources and limited accommodation space on precariously balanced vulnerable slopes. Particularly, the unplanned infrastructure development, lack of adequate drainage and excavation of roads through unstable debris slopes are some of the reasons that seem to have accelerated the ongoing slope instability and land subsidence. [ABSTRACT FROM AUTHOR]

The phenomenon of toppling deformation and failure is common in slopes with anti-dip structures, especially in soft metamorphic rock slopes. This paper aims to explore the instability mechanism of anti-dip layered soft metamorphic rock landslides. Taking the slope of a mining area in the southern Qinling Mountains of China as a geological prototype, a large-scale centrifuge model test and a numerical simulation based on the combined finite and discrete element method (FDEM) were performed. The deformation and failure process, failure mode, and failure path of the slope under rainfall and excavation conditions were simulated. The results show that both the physical centrifuge model test and the new numerical model test can simulate the instability process of anti-dip layered soft metamorphic rock slopes, and the phenomena simulated by the two methods are also very close. Rainfall mainly weakens the mechanical properties of rock, while the excavation at the slope toe mainly changes the stress field distribution and provides space for slope deformation, both of which accelerate the instability of the anti-dip soft metamorphic rock slope. The failure process of an anti-dip layered soft rock slope can be described as follows: bending of the rock layer–tensile fracture along the layer–flexural toppling and cracking perpendicular to the rock layer–extension and penetration of the tensile fracture surface–sliding and instability of the slope. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Asociación Geológica Argentina is the property of Asociacion Geologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)