Simulating retrogressive slope failure using two different smoothed particle finite element methods: A comparative study

Various smoothed particle finite element methods (SPFEMs) have been developed to simulate large deformation problems, but their efficiency and accuracy in simulating progressive landslides in sensitive clays have remained unclear. In this study, a series of numerical analyses are carried out to investigate the development of retrogressive landslides by two SPFEMs (an edge-based strain smoothing PFEM, ESPFEM, and a node-based strain smoothing PFEM, NSPFEM) in view of their outstanding performance in large deformation analysis. A strain-softening Mohr–Coulomb (MC) model is adopted to simulate the behaviour of sensitive clays during landslide, assuming a Poisson's ratio of 0.49 to ensure undrained conditions. The influence of mesh density on the development of retrogressive failure is evaluated for two SPFEMs. Numerical analyses of three mesh sizes (0.2 m, 0.15 m and 0.12 m) are carried out sequentially, with all results demonstrating that (1) the spread retrogressive landslides with horsts and grabens can be achieved by both SPFEMs with the adopted soil model, (2) run-out and retrogression distances decrease as mesh density increases for both methods, (3) retrogressive collapse occurs earlier for ESPFEM but is delayed for NSPFEM with increased mesh density, (4) NSPFEM allows faster calculations and reduces mesh dependency problems when compared with ESPFEM and (5) the increase of shape factor can accelerate retrogressive evolution of landslides. Finally, a real landslide in sensitive clay at Sainte-Monique, Quebec, is simulated to demonstrate ESPFEM's computational efficiency and accuracy.