Displacement-based design procedure for slope-stabilizing piles

Abstract

Vertical piles are widely employed around the world to prevent landslides, and they are commonly designed with the aim of reducing the soil displacement rate well before the activation of the potential failure mechanism. The design strategies usually adopted in engineering practice are often based on oversimplified approaches, not taking into account any realistic interaction mechanism between pile and soil, and they are not suitable for predicting the effectiveness of the mitigation structure in terms of reduction in the soil displacement rate. This paper attempts to address the problem by proposing a simplified displacement-based numerical procedure, providing engineers with a simple, physically based and easy-to-run tool, particularly useful in pre-dimensioning phases for the system. The importance of a correct description of the soil–pile mechanical interaction and even of possible nonlinearities in pile behaviour is quantitatively discussed by means of numerical analyses based on simplified geometries, proving that the soil–structure interaction forces cannot a priori be foreseen, but that their evaluation requires a displacement-based procedure. The proposed approach appears to be very useful even for prediction of the long-term behaviour of the system. This framework allows the capture of even the remarkable influence that the shape of the soil displacement profile has on the mechanical response of the system, thus implying that a reliable on-site monitoring system is necessary for the optimum design of the structure.