A novel implicit coupled hydro-mechanical SPFEM approach for modelling of delayed failure of cut slope in soft sensitive clay

Modelling of delayed failure of cut slopes in soft sensitive clays is a significant challenge because of three major features taking place simultaneously: large deformation of the slope up to failure, pore water pressure generation and dissipation in the slope, and complicated time-dependent deformation of sensitive clay. This paper proposes a novel fully hydro-mechanical coupled edge-based strain smoothed particle finite element (ES-PFEM) modelling approach for delayed failure of cut slope with three outstanding features: (1) the particle finite element method with low-order edge-based strain-smoothed element for large deformation analysis, (2) an efficient stabilization method for pore water pressure to circumvent the Babuška-Brezzi stability restriction and (3) the elasto-viscoplastic model considering time-dependency, anisotropy and destructuration of soft sensitive clays. The accuracy and efficiency of the proposed approach are first examined by simulating consolidation test and strip footing. Furthermore, an adaptive substepping algorithm is proposed for the elasto-viscoplastic model. Finally, a typical case of delayed failures of cut slopes with different angles in soft sensitive clays is simulated and analysed, demonstrating the predictive ability of the proposed approach. The relationship between slope angle, sensitivity of clay and time of failure occurring is obtained for predicting the slope failure time in practice.