Landslide Simulation Research Articles

Evaluating the performance of propagation models of flow-like landslides at regional scale

Propagation models of flow-like landslides can be calibrated by comparing on-site evidence of past occurrences with the propagation paths and the deposition zones resulting from numerical simulations of the phenomena. Most typically, the performance of these models is evaluated considering the events independently from one another and, heuristically, i.e., subjectively assessing the fit between numerical results and available on-site data. At regional scale, however, storms often trigger, within a given area, multiple landslides of the flow type that occur more or less simultaneously. At this scale, a procedure that objectively quantifies the success, or the errors, of the numerical simulations of multiple landslides is lacking. In this study, such a quantitative calibration procedure is proposed, and assessed, considering the debris flows that occurred in Sarno in 1998 (Italy). The numerical model used is called Debris Flow Predictor (DFP), which is able to simulate the propagation paths and the accumulation depths of multiple debris flows, at regional scale, from a series of predefined triggering areas. The model employs a cellular automata method with a probabilistic behavioral rule, which is a function of the adopted digital elevation model and a series of parameters related to the erosional, the depositional, and the spreading capacity of the propagating soil mass. The numerical simulations were evaluated over the study area considering the entire set of debris flow events, as well as the individual debris flows, following a preliminary discretization of both the mapped footprints and the remaining portion of the territory. The relative and total operator characteristic curves, in addition to 6 indicators derived from a confusion matrix, have been used to quantify the performance of the simulations. The results show that the quantitative evaluation of the numerical results is essential to properly calibrate the adopted model, i.e., to discriminate among different simulations arising from different sets of model parameters.

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

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

Coupled CFD-DEM simulation of submarine landslide movement behavior

Submarine landslide is a common disaster geological phenomenon in the ocean, which can be destructive to underwater infrastructure. Therefore, it is necessary to simulate the evolutionary behavior of submarine viscous landslides. In this paper, computational fluid dynamics (CFD) and discrete element method (DEM) are used to establish the fluid-solid coupling model of water-particle interaction. Firstly, the inter-particle cohesion model is introduced to train the coupled CFD-DEM analysis of the kinematic evolution process, and at the same time, two typical cases are carried out to verify the analysis. In the experimental simulation, the kinematic and morphological characteristics of the submarine landslide were simulated considering the viscous effect and initial velocity of the landslide, and the influence mechanism of the landslide motion and evolution process was investigated in depth. The results show that the coupled method can better simulate the motion of submarine landslide, and the viscous effect of the landslide has a significant influence on its kinematic and morphological characteristics, and the initial velocity also significantly affects the evolution and distribution characteristics of the particle flow field of each part of the landslide in the process of motion. This study is important for the simulation and effective prediction of the kinematic evolution process of real submarine landslides.

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

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

Mechanism and numerical simulation of a rapid deep-seated landslide in Van Hoi reservoir, Vietnam

At approximately 5:00 AM on December 16, 2016, a rapid and deep-seated landslide was triggered by intense rainfall in the Van Hoi irrigation reservoir in Binh Dinh province, Vietnam. The landslide generated an impulsive wave with a height of approximately 20 m, resulting in severe damage to the reservoir operation station. This study investigated the mechanisms behind the landslide's initiation and simulated its initiation and motion processes through site surveys, ring shear tests, and the LS-RAPID simulation model. The physical tests were conducted on two soil samples from the sliding zone to examine the landslide mechanism. The results indicated that only sample 2 (a sand sample of completely weathered gneiss rock) showed a high level of landslide mobility due to its liquefaction phenomena resulting in a rapid pore water pressure development and a significant strength loss.
 In contrast, sample 1 (a silty sand sample of residual soils) did not exhibit this behavior due to its high shear resistance value at a steady state. The findings suggest that the sliding plane of the Van Hoi landslide formed in the completely weathered gneiss layer, and the high mobility level of sample 2 is primarily responsible for its rapid movement. Notably, the LS-RAPID model successfully reproduced the landslide process using the geotechnical properties obtained in the ring shear experiments. The simulation showed that the Van Hoi deep-seated landslide was initiated from the lower middle slope at a critical value of 0.55 for the pore water pressure ratio and traveled at a high velocity of approximately 37.0 m/s. The consistency between the computer simulation results and the on-site evidence and recorded data highlights the reliability of the LS-RAPID model as a tool for assessing landslide hazards.

Analysis of Poplar’s (Populus nigra ita.) Root Systems for Quantifying Bio-Engineering Measures in New Zealand Pastoral Hill Country

Populus nigra ita. is an important tree species for preventing rainfall-triggered shallow landslides and hydraulic bank erosion in New Zealand. However, the quantification of its spatial root distribution and reinforcement remains challenging. The objective of this study is to calibrate and validate models for the spatial upscaling of root distribution and root reinforcement. The data were collected in a 26-year-old “Tasman” poplar stand at Ballantrae Hill Country Research Station in New Zealand. We assessed root distribution at different distances from the stem of four poplar trees and from eleven soil pits along a transect located in a sparse to densely planting poplar stand. 124 laboratory tensile tests and 66 field pullout tests on roots with diameters up to 0.04 m were carried out to estimate root mechanical properties. The results show that the spatial distribution of roots can be well predicted in trenches of individual tree root systems (R2 = 0.78), whereas it tends to overestimate root distribution when planting density was higher than 200 stems per hectare. The root reinforcement is underestimated within single tree root systems (R2 = 0.64), but it performs better for the data along the transect. In conclusion, our study provided a unique and detailed database for quantifying root distribution and reinforcement of poplars on a hillslope. The implementation of these models for the simulation of shallow landslides and hydraulic bank erosion is crucial for identifying hazardous zones and for the prioritization of bio-engineering measures in New Zealand catchments. Results from this study are useful in formulating a general guideline for the planning of bio-engineering measures considering the temporal dynamics of poplar’s growth and their effectiveness in sediment and erosion control.

Underground Displacement Measurement Method Based on Double Mutual Inductance Voltage Contour Model of Optimized Dual Kriging

Landslide is a common geological hazard. Existing displacement monitoring sensors for landslides are classified into surface displacement and underground displacement. However, current underground displacement sensors cannot effectively monitor the vertical displacement caused by soil accumulation of landslides, which cannot meet the needs of landslide monitoring. Therefore, this study has designed a three-dimensional underground displacement measurement sensor based on the double mutual inductance voltage contour method. Since the double mutual inductance voltage measurement model has low measurement accuracy due to low interpolation accuracy and complex location calculation method when solving the spatial position, the improved Dual-Kriging interpolation method based on quantum pigeon inspired algorithm is adopted to improve the original interpolation accuracy. The experimental results show that this method avoids the complex problem of Kriging interpolation calculation and improves the calculation speed. At the same time, the overall accuracy is significantly improved, reducing its fitting error and actual value to a maximum of three ADC12 resolutions. The landslide experiment on the landslide simulation experiment platform shows that the sensor can effectively reflect the displacement of underground soil, and has important application value for slope displacement monitoring.

Modeling probabilistic-based reliability assessment of gridded rainfall thresholds for shallow landslide occurrence due to the uncertainty of rainfall in time and space

Abstract This study aims to model a probabilistic-based reliability assessment of the gridded rainfall thresholds for shallow landslide occurrence (RA_GRTE_LS) to quantify the effect of the uncertainty of rainfall in time and space on the rainfall thresholds under consideration of local soil properties. The proposed RA_GRTE_LS model is developed by coupling the uncertainty analysis with the logistic regression equation using a significant number of the landslide-derived rainfall thresholds of the specific warning times. The 30 historical gridded hourly rainstorms at 10 study grids in the study area (Jhuokou River watershed) are used in 1,000 simulations of rainfall-induced shallow landslides under an assumption of the soil layer of 310 cm. The results reveal that the shallow landslide in the study area probably occurs at the time step of less than the 36th hour around the bottom of the soil layer (about 275 cm) during a rainstorm; also, using the proposed RA_GRTE_LS model, the resulting rainfall thresholds and quantified reliabilities, especially for the warning time of less than 18 h, exhibit a sizeable varying trend in space due to the variations in rainfall and soil properties; accordingly, the short-term rainfall thresholds for shallow landslide occurrence could be locally determined under acceptable reliability.

Modelling large-scale landslide using a GPU-accelerated 3D MPM with an efficient terrain contact algorithm

The material point method (MPM) simulation of large-scale landslides can provide useful information to response to landslide hazards in mountainous regions. However, the structured background meshes commonly adopted in MPM fail to accurately capture the complex terrain above which the sliding mass moves. In this work, a novel terrain contact algorithm is proposed and integrated into a GPU-accelerated 3D MPM to model large-scale landslides. The complex terrain is modelled by a fixed triangular surface mesh generated according to the digital elevation model (DEM) and the interaction between the sliding mass and the basal surface is modelled by a contact algorithm between the triangular surface mesh and the material points. Furthermore, a contact detection algorithm based on level-set functions is developed to improve the contact detection efficiency. The detailed computational formulations and numerical implementation based on GPU parallel computing are presented. After the correctness and the efficiency being verified by two numerical examples, the proposed method is applied to simulate the catastrophic Baige landslide that occurred in China in 2018. The results indicate that the present method is both accurate and efficient and can provide a useful tool for numerical study on landslides.

Simulating Landslide Generated Tsunamis in Palu Bay, Sulawesi, Indonesia

The results of an extensive series of numerical experiments of the GNOM-LS model for modelling the physical and energy characteristics of tsunami waves generated by landslides are presented. Based on the published data on the tsunami on 28 September 2018 in Palu Bay, we analysed the sensitivity of the distribution of wave heights along the coastline formed by the landslide system, depending on the characteristics of these landslides and model parameters. The complexity of the work lies in the lack of a holistic picture of the initial information about landslides, their number and accurate measurement data on the height of the waves of the event. We attempted to restore these conditions by comparing numerical simulations for various initialisations of the landslide system with available observational data. It is revealed that the simulated system has a very high sensitivity to the initial conditions and characteristics of landslides. An essential task of the work is interpreting a complex picture of the nonlinear interaction of tsunami waves with minor changes in the initial characteristics of landslides. Based on the numerical simulation of single landslides and a complete system of landslides, an analysis of the complex structure of the nonlinear interaction of tsunami waves is carried out.

Numerical simulation of submarine landslides and generated tsunamis: application to the on-going Mayotte seismo-volcanic crisis

Since May 2018, Mayotte Island has been experiencing seismo-volcanic activities that could trigger submarine landslides and, in turn, tsunamis. To address these hazards, we use the HySEA numerical model to simulate granular flow dynamics and the Boussinesq FUNWAVE-TVD numerical model to simulate wave propagation and subsequent inundations. We investigate 8 landslide scenarios (volumes from 11.25×10 6 m 3 to 800×10 6 m 3 ). The scenario posing the greatest threat involves destabilization on the eastern side of Mayotte’s lagoon at a shallow depth and can generate sea-surface deformations of up to 2 m. We show that the barrier reef surrounding Mayotte plays a prominent role in controlling water-wave propagation and in protecting the island. The tsunami travel time to the coast is very short (a few minutes) and the tsunami is not necessarily preceded by a sea withdrawal. Our simulation results provide a key to establishing hazard maps and evacuation plans and improving early-warning systems. Supplementary Materials: Supplementary material for this article is supplied as a separate file: crgeos-138-suppl.pdf Depuis mai 2018, l’île de Mayotte connaît une activité sismo-volcanique importante susceptible de déclencher des glissements de terrain sous-marins générant des tsunamis. Pour faire face à ces aléas, nous utilisons deux modèles numériques complémentaires : le modèle HySEA (simulant la dynamique des écoulements granulaires) et le modèle Boussinesq FUNWAVE-TVD (simulant la propagation des vagues et les inondations) pour étudier 8 scénarios de glissements sous-marins potentiels (volumes de 11,25×10 6 m 3 à 800×10 6 m 3 ). Les scénarios ayant le plus d’impact se situent à proximité de Petite Terre et à faible profondeur. Ils peuvent générer une élévation de la surface de la mer jusqu’à 2 m en zone habitée à Petite Terre. Nous montrons que la barrière de corail entourant Mayotte joue un rôle prépondérant dans le contrôle de la propagation des vagues et dans la protection de l’île. Le temps de trajet du tsunami jusqu’à la côte est très court (quelques minutes) et le tsunami n’est pas nécessairement précédé d’un retrait maritime. De telles observations sont essentielles pour construire des cartes d’aléas précises et des plans d’évacuation afin d’aider la population. Compléments : Des compléments sont fournis pour cet article dans le fichier séparé : crgeos-138-suppl.pdf

Time capsule for landslide risk assessment

ABSTRACT Landslides, one of the most common mountain hazards, can result in enormous casualties and huge economic losses in mountainous regions. In order to address the landslide hazards effectively, the geological society is required not only to develop in-depth understanding of landslide mechanism but also to quantify its associated risk. In this article, landslide risk assessment is categorised into two types, hard and soft risk assessments, and reviewed separately. The hard approach focuses on the mechanics and numerical simulations of individual landslides, subsequent consequences, and their uncertainty quantifications and probabilistic analyses while the soft approach explores the quantification of disaster risk components such as hazard and vulnerability at different scales of concern. It is hoped that this article can serve as a time capsule to link the preceding and following of landslide risk assessments and shed some light on future studies.

A modified friction-viscous solid boundary of the SPH method for landslide simulation

Bed friction characteristics are important factors controlling landslide movement processes. To address existing boundary condition deficiencies in describing the bed friction characteristics of landslide movements on complex terrain for the SPH method, a modified friction-viscous solid boundary condition is proposed. Within the solid boundary condition, the solid boundary is composed of line segments in 2D conditions and triangular segments in 3D conditions. The solid boundary is treated as a rigid material, and the SPH particle is treated as an elastic particle. The method used to calculate the values and directions of the contact, friction and viscous forces is presented. The proposed solid boundary condition is validated through water and granular material column collapse experiments. The dynamic process of a realistic landslide on complex terrain is simulated to demonstrate the applicability of the proposed solid boundary condition. Compared with the existing solid boundary condition, the proposed solid boundary condition has advantages in embedding friction model and wall function, exerting friction and viscosity force, keeping the stability of contact force, and establishing a complex terrain model.

Application of Smoothed Particle Hydrodynamics (SPH) for the Simulation of Flow-Like Landslides on 3D Terrains

Flow-type landslide is one type of landslide that generally exhibits characteristics of high flow velocities, long jump distances, and poor predictability. Simulation of its propagation process can provide solutions for risk assessment and mitigation design. The smoothed particle hydrodynamics (SPH) method has been successfully applied to the simulation of two-dimensional (2D) and three-dimensional (3D) flow-like landslides. However, the influence of boundary resistance on the whole process of landslide failure is rarely discussed. In this study, a boundary condition considering friction is proposed and integrated into the SPH method, and its accuracy is verified. Moreover, the Navier-Stokes equation combined with the non-Newtonian fluid rheology model was utilized to solve the dynamic behavior of the flow-like landslide. To verify its performance, the Shuicheng landslide event, which occurred in Guizhou, China, was taken as a case study. In the 2D simulation, a sensitivity analysis was conducted, and the results showed that the shearing strength parameters have more influence on the computation accuracy than the coefficient of viscosity. Afterwards, the dynamic characteristics of the landslide, such as the velocity and the impact area, were analyzed in the 3D simulation. The simulation results are in good agreement with the field investigations. The simulation results demonstrate that the SPH method performs well in reproducing the landslide process, and facilitates the analysis of landslide characteristics as well as the affected areas, which provides a scientific basis for conducting the risk assessment and disaster mitigation design.

Research on the Landslide Prediction Based on the Dual Mutual-Inductance Deep Displacement 3D Measuring Sensor

Landslides are frequent and catastrophic geological hazards, and forecasting their movement is an important aspect of risk assessment and engineering prevention. Based on the integrated deep displacement three-dimensional measuring sensor with sensing unit array structure, an improved multivariable grey model based on dynamic background value and multivariable feedback is proposed to build predictive models for the evolutionary condition of landslides. In the modeling process, the traditional grey model was replaced by extracting the trend information of each variable, instead of summing up each independent variable after assigning weights to it, besides, the Whale Optimization Algorithm (WOA) is used to modify the default value in the model’s background variables. By predicting more than 1000 sets of deep displacement monitoring data collected in the landslide simulation test conducted at the landslide simulation test device, the displacement prediction accuracy of our purposed model is 26%, 47%, and 87% respectively higher than the optimizing grey model (OGM) for three sensing units at different depths. Moreover, a new landslide risk assessment approach based on the orientation vector angle is proposed to make stability discriminations which is less susceptible to volatile data than the TOPSIS-Entropy weight theory and avoids the problem of lack of uniform standards due to the complexity of environmental factors.

Two-layer two-phase material point method simulation of granular landslides and generated tsunami waves

Numerical modeling of the entire process of tsunamis generation by granular landslides is very difficult and challenging as it involves the soil–water interaction, large deformation of soil, and the fluidization and sedimentation of sand. In this study, a computational model based on the two-layer two-phase material point method (MPM) is developed to simulate granular-landslide-generated tsunamis, wherein the soil–water interaction, large deformation of soil, and fluidization and sedimentation of sand are well modeled. The soil behavior is described using a Mohr–Coulomb model with a non-associated flow rule, while the water is considered as weakly compressible. Furthermore, three different benchmark problems are simulated. All computed results well agree with the corresponding analytical solution and laboratory test data, verifying the effectiveness of the proposed two-layer two-phase MPM for modeling the subaerial and submerged granular-landslide-generated tsunamis. Additionally, the influence of different soil material parameters on the water wave generated by the subaerial granular landslide is investigated.

Simulation of the Vaiont landslide via multi-body material point method with cohesive frictional interfaces

Simulation of the Vaiont landslide via multi-body material point method with cohesive frictional interfaces

Recent Technological and Methodological Advances for the Investigation of Submarine Landslides

Submarine landslides have attracted widespread attention, with the continuous development of ocean engineering. Due to the recent developments of in-situ investigation and modelling techniques of submarine landslides, significant improvements were achieved in the evolution studies on submarine landslides. The general characteristics of typical submarine landslides in the world are analyzed. Based on this, three stages of submarine landslide disaster evolution are proposed, namely, the submarine slope instability evolution stage, the large deformation landslide movement stage, and the stage of submarine landslide deposition. Given these three stages, the evolution process of submarine landslide disaster is revealed from the perspectives of in-situ investigation techniques, physical simulation, and numerical simulation methods, respectively. For long-term investigation of submarine landslides, an in-situ monitoring system with long-term service and multi-parameter collaborative observation deserves to be developed. The mechanism of submarine landslide evolution and the early warning factors need to be further studied by physical modelling experiments. The whole process of the numerical simulation of submarine landslides, from seabed instability to large deformation sliding to the impact on marine structures, and economizing the computational costs of models by advanced techniques such as parallel processing and GPU-accelerators, are the key development directions in numerical simulation. The current research deficiencies and future development directions in the subject of submarine landslides are proposed to provide a useful reference for the prediction and early warning of submarine landslide disasters.

Regional-scale assessment of earthquake-induced slope displacement considering uncertainties in subsurface soils and hydrogeological condition

Realistic prediction of coseismic landslides is crucial for the design of civil infrastructures and geotechnical systems in seismically active regions. Coseismic landslides are complicated nonlinear and large-deformation processes triggered by ground shaking. To date, many gaps still remain in the scientific understanding of the landslides, particularly in areas lacking information on the subsurface stratigraphy. Analytical methods for estimating coseismic landslides have been based on highly simplified models, where many key influential factors have been overlooked, leading to large uncertainty in using empirical models for landslide prediction. In addition, more evidence recently underscores the necessity of modeling coupled effects between topography and soil amplification, which gives rise to complex wave propagation patterns due to scattering and diffracting of waves within the low-velocity near-surface layers. Neglecting topographic amplification and soil layers could result in significantly underpredicted regional-scale hazards of landslides. In this study, a regional-scale coseismic landslide simulation is carried out using the integral Spectral Element Method (SEM)-Newmark method for Hong Kong Island to quantify the coupled effect of 3D topography, subsurface soil condition as well as hydrogeological conditions. By leveraging extensive geological borehole data, a rigorous statistical model that characterizes uncertainties associated with subsurface soils is established. Influence of key factors that are not well considered in previous coseismic landslide studies, such as variation in irregular rockhead and spatially distributed shear-wave velocity are quantitatively analyzed. Numerical results demonstrate that by rigorously incorporating multiple sources of subsurface soil uncertainties, the total area of landslides in the study region can increase up to 30% compared with benchmark model as evidenced in the physics-based numerical simulation. These case studies will provide a valuable opportunity to revisit key factors that influence coseismic landslides using measured field data.

A deformation-dependent coupled Lagrangian/semi-Lagrangian meshfree hydromechanical formulation for landslide modeling

The numerical modelling of natural disasters such as landslides presents several challenges for conventional mesh-based methods such as the finite element method (FEM) due to the presence of numerically challenging phenomena such as severe material deformation and fragmentation. In contrast, meshfree methods such as the reproducing kernel particle method (RKPM) possess unique features conducive to modelling extreme events such as the absence of a structured mesh and the ease of adaptive refinement, among others. While the semi-Lagrangian reproducing kernel (SL-RK) shape functions of RKPM defined in the current configuration have proven to be effective in extreme event modelling, the computational cost for the re-evaluation of the shape functions at every time step is costly. In this work, a deformation-dependent coupling of the Lagrangian reproducing kernel (L-RK) and SL-RK approximations is proposed for the solution of a hydro-mechanical formulation for effective simulations of landslides. The ramp function is constructed based on an equivalent plastic strain as a deformation-dependent transition from L-RK shape functions to SL-RK ones as the deformation progresses. The particular focus of the paper will be on modelling seepage-induced landslides with a mixed u–p formulation to couple the solid and fluid phases. Examples are presented to examine the effectiveness of this coupled Lagrangian/semi-Lagrangian reproducing kernel (L–SL RK) formulation and to highlight its performance in landslide modelling.