Trends in large-deformation analysis of landslide mass movements with particular emphasis on the material point method

124

SUMMARYThis paper presents a dynamic fully coupled formulation for saturated and unsaturated soils that undergo large deformations based on material point method. Governing equations are applied to porous material while considering it as a continuum in which the pores of the solid skeleton are filled with water and air. The accuracy of the developed method is tested with available experimental and numerical results. The developed method has been applied to investigate the failure and post-failure behaviour of rapid landslides in unsaturated slopes subjected to rainfall infiltration using two different bedrock geometries that lie below the top soil. The models show different failure and post-failure mechanisms depending on the bedrock geometry and highlight the negative effects of continuous rain infiltrations.

Section: Introductionmentioning

confidence: 99%

Modelling landslides in unsaturated slopes subjected to rainfall infiltration using material point method

Bandara

Ferrari

Laloui

2016

124

“…More recently, MPM has also been extended to considering pore water pressure to simulate hydro‐mechanical coupling problems. Examples reported in the literature include levee and slope failures (see a recent review on MPM by Soga et al ).…”

Section: Introductionmentioning

confidence: 99%

Multiscale modeling of large deformation in geomechanics

Liang

Zhao

2019

Summary Large deformation soil behavior underpins the operation and performance for a wide range of key geotechnical structures and needs to be properly considered in their modeling, analysis, and design. The material point method (MPM) has gained increasing popularity recently over conventional numerical methods such as finite element method (FEM) in tackling large deformation problems. In this study, we present a novel hierarchical coupling scheme to integrate MPM with discrete element method (DEM) for multiscale modeling of large deformation in geomechanics. The MPM is employed to treat a typical boundary value problem that may experience large deformation, and the DEM is used to derive the nonlinear material response from small strain to finite strain required by MPM for each of its material points. The proposed coupling framework not only inherits the advantages of MPM in tackling large deformation engineering problems over the use of FEM (eg, no need for remeshing to avoid mesh distortion in FEM), but also helps avoid the need for complicated, phenomenological assumptions on constitutive material models for soil exhibiting high nonlinearity at finite strain. The proposed framework lends great convenience for us to relate rich grain‐scale information and key micromechanical mechanisms to macroscopic observations of granular soils over all deformation levels, from initial small‐strain stage en route to large deformation regime before failure. Several classic geomechanics examples are used to demonstrate the key features the new MPM/DEM framework can offer on large deformation simulations, including biaxial compression test, rigid footing, soil‐pipe interaction, and soil column collapse.

“…Furthermore, the interaction between fluid nodes and solid nodes requires special treatment in PFEM . Recently, a considerable progress has been made in the application of the MPM in geotechnical engineering problems, although difficulties regarding high computational cost and cell crossing noise are yet to be completely addressed …”

Section: Introductionmentioning

confidence: 99%

Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

Ghaffaripour

Esgandani

Khoshghalb

et al. 2019

Summary This paper presents the first application of an advanced meshfree method, ie, the edge‐based smoothed point interpolation method (ESPIM), in simulation of the coupled hydro‐mechanical behaviour of unsaturated porous media. In the proposed technique, the problem domain is spatially discretised using a triangular background mesh, and the polynomial point interpolation method combined with a simple node selection scheme is adopted for creating nodal shape functions. Smoothing domains are formed on top of the background mesh, and a constant smoothed strain, created by applying the smoothing operation over the smoothing domains, is assigned to each smoothing domain. The deformation and flow models are developed based on the equilibrium equation of the mixture, and linear momentum and mass balance equations of the fluid phases, respectively. The effective stress approach is followed to account for the coupling between the flow and deformation models. Further coupling among the phases is captured through a hysteretic soil water retention model that evolves with changes in void ratio. An advanced elastoplastic constitutive model within the context of the bounding surface plasticity theory is employed for predicting the nonlinear behaviour of soil skeleton. Time discretisation is performed by adopting a three‐point discretisation method with growing time steps to avoid temporal instabilities. A modified Newton‐Raphson framework is designed for dealing with nonlinearities of the discretised system of equations. The performance of the numerical model is examined through a number of numerical examples. The state‐of‐the‐art computational scheme developed is useful for simulation of geotechnical engineering problems involving unsaturated soils.