Stabilisation of excavated slopes with piles in soils with distinctly different strain softening behaviour

The majority of existing design procedures for slope stabilization with piles treat the pile only as an additional force or moment acting on the critical slip surface of the un-stabilised slope, effectively ignoring any interaction of the pile with the evolution of the failure mechanism. This paper presents a numerical investigation that challenges this assumption, demonstrating the importance of the soil-pile interaction. Two dimensional plane-strain hydro-mechanically coupled finite element analyses were performed to simulate the excavation of a slope, considering materials with both a strain softening and non-softening response. The impact of pile position and time of pile construction on the stability of a cutting were parametrically examined, comparing and contrasting the findings for the different material types. The results suggest that an oversimplification during design regarding the soil/pile interaction could either entirely miss the critical failure mechanism (unconservative) or provide a conservative stabilisation solution.