Numerical Investigation of Passive Loads on Piles in Soft Soils

Abstract

If piles are installed in slopes or next to heavy loads, especially in soft cohesive soils, piles are often loaded by horizontal ground displacements. In this case the pile shafts are stressed by shear forces and bending moments. Initially, a structured overview of existing analytical methods for estimating passive loading on piles by horizontal movement of surrounding soil is presented. While one component of passive load is determined by the shear strength of the soil, the other often negligible component depends on the relative velocity between the pile and surrounding soil. For mobilizing the maximum passive load on pile, the soil often has to undergo large deformations. In classical Lagrangian Finite Element Method these deformations distort the finite element mesh which might lead to inaccurate results or the numerical analysis does not converge to a stable solution. Hence, numerical study of pile soil interaction needs more sophisticated modelling techniques like the Arbitrary Lagrangian-Eulerian (ALE) method, the Coupled Eulerian-Lagrangian (CEL) method or the Material Point Method (MPM) to minimize numerical problems caused by distorted mesh. These methods are discussed briefly and their potential is shown for a simple 2D plane strain problem of a single passive loaded pile.