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Rapid flow-like landslides frequently occur in mountainous regions. To mitigate the disasters caused by these landslides, it is crucial to develop robust numerical models that can accurately predict their run-out processes. Models based on the material point method (MPM) offer significant advantages in simulating large deformation issues in geomaterials, including landslides. However, applying these models to accurately simulate real-world rapid flow-like landslides remains a challenge, primarily due to the complexities involved in handling the three-dimensional (3D) sliding bed boundary. This paper introduces a novel 3D MPM model specifically designed for simulating rapid flow-like landslides that propagate across curved beds. The constraints of the sliding bed on the landslide are imposed by the boundary nodes close to the bed. These boundary nodes carry information about the normal vector of the sliding bed, derived directly from the digital terrain model (DTM). Furthermore, the model integrates a hybrid formulation that combines the Full Lagrangian Implicit Particle (FLIP) method with the Particle In Cell (PIC) method, facilitating a stable solution for the velocity and position of material points. The effectiveness of the proposed model is confirmed through a numerical analysis of a rigid block sliding down an inclined plane and an experiment of sand flow on a curved bed. The simulation results from these two benchmark scenarios align closely with both analytical and experimental data, attesting to the validity of the model. The model is then applied to analyze a rapid flow-like landslide that occurred in Gansu Province, China, characterized by a curved sliding bed. The outcomes illustrate the model's capability to efficiently capture the landslide's climbing and turning motions induced by the meandering topography. Moreover, it successfully reproduces the main deposition characteristics observed in the field, demonstrating the model's strong suitability for simulating the propagation of rapid flow-like landslides on naturally curved beds. [ABSTRACT FROM AUTHOR]

Entrainment is a key factor that often alters the mobility of landslides, particularly in rapid flow-like loess landslides (RFLL). Despite its significance, the entrainment process in RFLL is not well understood due to the scarcity of detailed field data. This study employs an enhanced material point method (MPM) model to investigate the entrainment process of RFLL. The model's accuracy was first validated through granular column collapse experiments conducted on an erodible bed. Subsequently, three-dimensional (3D) simulations were performed to analyze the run-out behavior of a real RFLL, specifically focusing on the entrainment phenomenon. The simulation results indicate that plowing is the main entrainment pattern of the RFLL. During the entrainment process, the loess landslide remains largely distinct from the disturbed terrace material. Momentum from the loess landslide is transferred to the terrace material, leading to significant upheaval deformation within the terrace. Three deformation structures are formed in the disturbed terrace. In the rear part of the disturbed terrace, an anti-dip zone is formed under the loess-terrace interface, where the strata rotate and dip in the opposite direction to the landslide's motion. A shear zone is formed in the middle part of the disturbed terrace, where the strata bend due to the horizontal compression from the landslide. Shear failure occurs in this zone, leading to undulations in the terrace surface. In the front part, a titling zone is generated, where the strata dip towards the sliding direction, but shear failure has not yet formed. Furthermore, the combined effects of lateral spreading and shear failure result in the formation of multiple arc-shaped ridges within the shear zone of the disturbed terrace. The MPM model can satisfactorily reproduce these geomorphic characteristics of the deformed terrace caused by entrainment, and the simulation results agree reasonably well with field observations. This research sheds light on the entrainment mechanism of the RFLL. [ABSTRACT FROM AUTHOR]

Rockslide-debris flow may cause catastrophic damages because of its high speed and long run-out distance. The influences of slope gradient and gully channel on the entrainment, deposition, and run-out behavior of this type of landslide were not sufficiently investigated by previous studies. To achieve a better understanding toward this type of landslide, a recent rockslide-debris flow that occurred in the Northern Apennines of Italy is studied through field investigation and numerical simulation. The run-out process of this landslide is simulated by an improved depth-averaged model, paying special attention to analyzing the influence of slope gradient and gully channel. The simulation results are compared with the detailed field data of entrainment and deposition distributions. It shows that the depth-averaged model can reasonably simulate the entrainment and deposition characteristic of this landslide by adopting different basal friction strengths for the rockslide region and debris flow region. Entrainment occurs in both high and low slope gradient zones. However, entrainment can only be observed in the high slope gradient zones, while in the low gradient zones, the post-failure topography shows accumulation and deposition. The simulation results also demonstrate that the presence of a gully channel is a key factor in determining landslide mobility and run-out distance. In comparison to a landslide with similar size and geological settings but without a gully channel, the run-out distance is much less, and the landslide does not develop into a flow. [ABSTRACT FROM AUTHOR]

Landslides may be triggered by a variety of external factors and can lead to dramatic human and economic consequences. Systematically investigating all possible parameters that could potentially influence the extent of a landslide is costly and generally not practical. In this paper, a methodology to numerically assess the impact of potential landslides is proposed. In this approach the landslide simulations were carried out using finite element model estimates of potential failure volume as an input into a discrete element model which is used to assess run-out and consequences. A statistical design of experiments was implemented to determine the most important factors influencing the landslide extent thereby significantly reducing the number of simulations required. The method is illustrated on a case study of potential failure of an overburden dump at a coal mine. Over the parameter ranges considered, the particle–particle (rock block to rock block) friction coefficient and the volume of failing material were determined to be the most important factors influencing the extent of the landslide. A systematic analysis of varying the particle–particle friction coefficient was then undertaken to better understand the dynamics of the collapse and different types of collapses were identified between low and high inter-particle friction coefficients. The methodology proposed in this paper should be of interest to practitioners as a way to thoroughly yet efficiently identify and assess the main factors influencing a potential landslide on sites at risk. [ABSTRACT FROM AUTHOR]

Various risk management measures have been applied to reduce risks associated with the debris flow; however, only a few studies have adopted the economic benefit to evaluate measure effectiveness. The present study sought to explore debris flow risks at a catchment scale and establish the appropriate risk-reducing measures. The Chengbei Gully debris flow in Shanxi province (China) was selected for the case study. High-resolution topographic data of the drainage basin were obtained using the airborne LiDAR technology. FLO-2D software was used to simulate the debris flow process to perform hazard zonation. Vulnerability was estimated based on the location of elements at risk within the hazard zones and the field survey. Several structural and non-structural measures for controlling risks were proposed based on the risk assessment results, and the benefit–cost ratio was used to analyze their effectiveness. The findings indicated that the rainfall event triggering the Chengbei Gully debris flow had an 80-year return period. The total risk under this rainfall condition was 2.3 × 105 $, which was an unacceptable level according to the criteria of tolerance risk. The findings showed that the engineering measure was the best mitigation approach for the Chengbei Gully debris flow with a benefit of 1.35 million $ and a benefit–cost ratio of 6.43.

Bed entrainment changes the rheology of the sliding mass and the topography of the sliding surface, finally influencing the propagation of flow-like landslides. In previous studies, both empirical methods and physically based methods have been used to simulate bed entrainment. However, the influences of bed entrainment on the rheology and topography of flow-like landslides were not deeply explored. In this paper, the physically based model proposed by Fraccarollo and Capart (J Fluid Mech 461:183–228, 2002) is adopted to calculate the bed entrainment rate, and a new method is proposed to consider the rheology change associated with bed entrainment in flow-like landslides. The new rheology change method and the Fraccarollo and Capart model are incorporated into a quasi-3D finite difference code to analyze an ideal case and two typical flow-like landslides. The two real landslides are the Dabaozi landslide and the Dagou landslide in the Chinese Loess Plateau. They represent two different bed entrainment scenarios: the erodible mass is relatively thick in the Dabaozi landslide, while that of the Dagou landslide is relatively thin. The results show that both the topography and rheology changes have a significant influence on the propagation of flow-like landslides: (1) the rheology change mainly influences the run-out distance of a landslide, while the topography change mainly impacts the lateral spreading; (2) entraining soft materials can significantly increase the run-out distance of a flow-like landslide; (3) the topography change can obviously constrain the lateral spreading of those landslides when the erodible mass is relatively thick. In addition, it shows that the rheology change and topography change influence each other in the propagation of a flow-like landslide, and the proposed rheology change method in this paper can properly reflect this interactive process. [ABSTRACT FROM AUTHOR]

The first part of the paper presents a brief description of the material point method (MPM) including the governing equations, solution scheme and a benchmark problem of soil collapse simulated using the method. In the second and third part of the paper, the post-failure runout process of the Wangjiayan landslide is simulated and analyzed. The landslide's final topography and information from post-failure in-situ survey and laboratory tests are used to constrain the accuracy of computational results. The kinematic behaviors of the failure mass are investigated in terms of displacement, velocity, effective plastic strain fields and topography changes during the movement. Comparisons are made between conditions with and without buildings on the deposition area. Numerical computations demonstrate that the presence of buildings on the sliding path strongly governs the flow regime, run-out distance, velocity, strain field and final deposition topography of the landslide. So it is very essential to incorporate the effects of buildings in the modelling and analyses. Numerical results considering buildings show that the slide lasts about 30 s with the most rapid phase occurring between 6 and 12 s, and that the maximum simulated velocity among the sliding particles in the landslide is 43.5 m/s, indicates that the moving of the landslide mass was very fast. The run-out distance simulated with MPM matches the measured post-earthquake topography well, whereas the shape of the simulated deposition zone is a little differs. The buildings influence the sliding by shortening the overall run-out distance, decelerating the movement of the bottom layer, and increasing the internal deformation and mixing among deposition layers. [ABSTRACT FROM AUTHOR]

Many landslides can often be characterized as a sort of landslides which move rapidly like flowing fluid and thus have a long run-out. They usually cause large damage and casualties especially when they are trigged by an earthquake or heavy rain. Numerical simulations of flow-like landslides are difficult due to the existence of free surface and large flow deformations. In this work, the smoothed particle hydrodynamics (SPH) method is applied to model two- and three-dimensional flow-like landslides for the run-out analysis. This is because SPH method is a meshfree, Lagrangian particle method, and is believed to be superior to conventional numerical methods in treating free surfaces, moving interfaces, and large deformations; hence, it is ideal in describing the complex fluidization characteristics in flow-like landslides. In this paper, a Bingham flow model and Navier-Stokes equations are incorporated into the SPH frame work, in which fluids are discretized by flow particles, and 3D terrain topography from GIS is represented by surface (or solid wall) particles. An improved SPH method is first applied to simulate the whole run-out processes of three flow-like landslides, which were triggered by Wenchuan earthquake that occurred in China in 2008. The effectiveness of the improved SPH method in modeling flow-like landslides is demonstrated by the good agreement of the 3D profile simulation results obtained from the present SPH simulation with field observation and results from other open sources. The SPH method is then used to predict the run-out area of Jinpingzi landslide. [ABSTRACT FROM AUTHOR]

Abstract: This study presents the run-out analysis of the Daguangbao landslides subjected to near-fault multi-direction earthquake forces using discontinuous deformation analysis (DDA). The Daguangbao landslide is the largest landslide induced by the 2008 Wenchuan earthquake. In order to investigate the effects of near-fault seismic force on landslide run-out, kinematic behavior of sliding mass is simulated by a dynamic discrete numerical analysis method called DDA. In this simulation, based on the shape of failure surface and the feature of slope geology, the whole slope is divided into three parts: base block, upper sliding mass, and lower sliding mass. Then two sliding masses are divided into the smaller discrete deformable blocks based on pre-existing discontinuities. Size effect of the huge landslide is also considered. Baseline corrected real horizontal and vertical ground motions are taken as volume force acting to the base block. The results show that seismic force has a significant influence on the landslide progression, sliding distance, and shape of post-failure. Results of the horizontal-and-vertical situation are in good agreement with those obtained from post-earthquake field investigation, remote sensing image and description from the survivors. [Copyright &y& Elsevier]

Most municipal solid waste (MSW) is disposed of in landfills. Over the past few decades, catastrophic flow slides have occurred in MSW landfills around the world, causing substantial economic damage and occasionally resulting in human victims. It is therefore important to predict the run-out, velocity and depth of such slides in order to provide adequate mitigation and protection measures. To overcome the limitations of traditional numerical methods for modelling flow slides, a mesh-free particle method entitled smoothed particle hydrodynamics (SPH) is introduced in this paper. The Navier–Stokes equations were adopted as the governing equations and a Bingham model was adopted to analyse the relationship between material stress rates and particle motion velocity. The accuracy of the model is assessed using a series of verifications, and then flow slides that occurred in landfills located in Sarajevo and Bandung were simulated to extend its applications. The simulated results match the field data well and highlight the capability of the proposed SPH modelling method to simulate such complex phenomena as flow slides in MSW landfills. [ABSTRACT FROM PUBLISHER]

Flow-like landslides have caused significant damage and casualties worldwide. However, studying such phenomena with traditional simulation methods is made difficult by their complex fluidization characteristics. In this paper, we use smoothed-particle hydrodynamics (SPH) for the run-out analysis of flow-like landslides. Compared with conventional methods, the proposed SPH modeling technique is the combination of a Bingham flow model and Navier-Stokes equations in the framework of computational fluid dynamics. At first, two benchmark problems of dam break and granular flow are simulated and verified to evaluate the accuracy of the SPH model. Then, run-out analyses are performed for flow-like landslides triggered by the Ms 8.0 Wenchuan earthquake that occurred on 12 May 2008 in Sichuan Province, China. Run-out analyses of the Tangjiashan, Wangjiayan, and Donghekou landslides are conducted by the application of SPH models to real flow-like landslides. All simulations show good agreement with characteristics of flow-like landslides observed in the field. We have found that numerical modeling can capture the fundamental dynamic behavior of these flow-like landslides and produce preliminary results for hazard assessment and site selection for reconstruction in earthquake-prone areas. [ABSTRACT FROM AUTHOR]