A strong earthquake can stimulate large number of landslides, which can cause serious economic and person loss. Understanding the failure mechanisms of the seismically induced landslide and the resulting landmass runout is crucial. In this paper, two continuum models are examined which allow the simulation of large deformations. The first is performed by coupling a Lagrangian FE with an Eulerian description using the software Abaqus. The coupling procedure allows simulating the rock material as a flow running over rigid base. Material Point Method (MPM) is an innovative mesh-free particle method performs the coupling procedure in an arbitrary form where the natural movement of the material is traced. A frictional contact algorithm is included whereas an artificial damping is introduced in MPM to resemble the material damping. Moreover, a strain smoothening-technique is implemented to relax the numerical problem associated with using low-order tetrahedral element. The potential of applying the two approaches to simulate the failure of rock landslide is presented.

1 Introduction

The stability of slopes is one of the prominent problems in practical engineering. The major causes responsible for triggering a landslide includes heavy rainfall, imposed loads, strength degradation due to weathering and seismic excitation. The earthquake–induced landslides are among the most destructive slope movements, where the excessive failure might take place (Omidvar et al. 2011). In some of the cases, it becomes inevitable to study the behaviour of the slopes even after the failure as the large scale movement over broad areas can result in serious damages and casualties. In these cases, the failures cannot be prevented, but it becomes a primary interest of research to know the extent and probability of an eventual slide to reduce the damage.

Numerical methods based on mesh deformation, e.g. Finite Element Method (FEM), have difficulties in modelling large deformations due to problems of mesh distortion and entanglement. In order to such type of large deformation problems, various methods have been proposed by coupling the two frame of references in a unified approach. Coupled Eulerian-Lagrangian (CEL) method is one of these methods, in which an updated Lagrangian finite element method (FEM) is coupled with the Eulerian description via interface models. The FE-software Abaqus utilised this feature and therefore it has been used in this paper. The Material Point Method (MPM), which is an innovative mesh-free particle method, performs the coupling procedure in an arbitrary form where the natural movement of the material is traced. MPM has been applied for many geotechnical applications involving large deformation of collapsing slopes and landslides (see for example Andersen & Andersen 2010, Hamad et al. 2013). In this paper, a strain-smoothening techniques based on nodal mixed discretisation has been implemented in MPM to relax the mesh locking problem, whereas the frictional contact algorithm is extended so that a prescribed velocity can be assigned directly to one of the two bodies in contact. Moreover in this paper, the two methods (MPM and CEL) have been applied to a landslide progression failure occurred during the 1999 Chi-Chi earthquake of Taiwan. To show the potential of applying the two continuum based models, some results are presented.

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