Large-deformation finite-element modelling of earthquake-induced landslides considering strain-softening behaviour of sensitive clay

Abstract

Large-scale landslides in sensitive clays cannot be explained properly using the traditional limit equilibrium or Lagrangian-based finite-element (FE) methods. In the present study, dynamic FE analysis of sensitive clay slope failures triggered by an earthquake is performed using a large-deformation FE modelling technique. A model for post-peak degradation of undrained shear strength as a function of accumulated plastic shear strain (strain-softening) is implemented in FE analysis. The progressive development of “shear bands” (the zone of high plastic shear strains) that causes the failure of a number of soil blocks is simulated successfully. Failure of a slope could occur during an earthquake and also at the post-quake stage until the failed soil masses come to a new static equilibrium. Upslope retrogression and downslope runout of the failed soil blocks are examined for varying geometries and soil properties. The present FE simulations can explain some of the conditions required for different types of seismic slope failure (e.g., spread, flowslide or monolithic slides) to be triggered, as observed in the field.

Application of smoothed particle hydrodynamics (SPH) for simulating various geotechnical problems

“…cubic spline function, which has the advantages of the Gaussian one and also compact support, has the form 3 2 h 3 in one, two and three dimensions, respectively. The next step is particle approximation which is represented as with its derivative where where r ij is the distance between particles i and j.…”

“…However, if there is a large deformation that severely distorts the mesh, an entire simulation will eventually blow up. Although some FEM developments found in technical writings incorporate arbitrary Lagrangian behaviors [3], they are not always capable of realistically simulating large deformation processes. In addition, the finite difference method (FDM) has been used in many applications, together with FEM, to capture the entire deformation process.…”

The seismic microzonation study of Pescara del Tronto (Central Italy) during and after the Central Italy earthquake sequence.

“…In fact, in-situ geotechnical tests were almost impossible to collect due to restrictions for safety reasons and this limited the possibility to implement a more sophisticated analysis technique (e.g. Garevski et al 2013;Islam et al 2019) to take in account also dynamic actions on landslides, adopting proper procedures consistent with a complete L3SM study sensu (CTMS 2017). The susceptibility assessment was carried out without considering any seismic action, except for the slope stability analysis of deep-seated landslide that was accomplished including a pseudo-static approach and which results allowed to rule out such deep-seated landslide occurrence (see Appendix 1 for details).…”

Large deformation dynamic analysis of progressive failure in layered clayey slopes under seismic loading using the particle finite element method

“…In this paper, we focus on investigating the slope failure in layered clay of strain softening subjected to seismic loading. Owing to the low permeability of clays, the effects of the dissipation of pore water pressure are limited and thus the total stress analysis is performed which is in line with the studies for landslides in clays in [7,12]. For comparison purpose, a two-layer slopes with and without strain softening are studied using static analysis to determine the corresponding FOS.…”

“…More recent development of numerical techniques for large deformation analysis in geotechnics provides the possibility of simulating both the failure and post-failure stages. Representative numerical approaches of this capability include, but are not limited to, the Arbitrary Lagrangian-Eulerian (ALE) technique [8], the Coupled Eulerian-Lagrangian (CEL) method [12,30], the Material Point Method (MPM) [32], the Particle Finite Element Method (PFEM) [27,46,48], and the Smooth Particle Hydrodynamics (SPH) [9,23,28,38,44,45]. Recently, the CEL method has been adopted to investigate the large deformation behavior of clayey slopes under seismic loading with the weakening of clays being concerned [12].…”