Static liquefaction modelling of a landslide with the material point method

Abstract

Flow-like landslides may occur when excess pore water pressures develop in liquefiable materials under saturated or partially saturated conditions, causing rapid movement of the failed mass and long run-out distances. Its modelling requires a numerical method able to deal with large deformations combined with an advanced constitutive model to simulate the liquefac-tion process of mobilized mass during landsliding. This study focuses on the Ta-Ger constitutive model, based on critical state theory, to demonstrate its capabilities to capture characteristic features of sand behaviour including the liquefaction potential under saturated and partially saturated conditions. The model is incorporated into a large deformations numerical code based on the Material Point Method (MPM) and verified by reproducing undrained triaxial test paths of loose and dense soils. The numer-ical tool proposed is, then, applied to investigate a real case of flow-slide induced by static liquefaction. Data from field and laboratory tests confirmed the liquefaction susceptibility and the contractive tendency of the material involved and allowed to calibrate Ta-Ger model parameters. The results contribute to understand the complex behaviour of a natural flow-slide, charac-terized by transient generation and dissipation of excess pore pressures that affect the evolution of soil shear strength in the post-failure stage.