Passive load estimation on single piles and pile groups from visco-plastic mud-flow

If piles are installed in creeping slopes or next to heavy loads in soft soils (with high water content) they may be loaded due to large, progressive horizontal ground displacements. In such cases pile shafts will be stressed by heavy shear forces and bending moments that may lead to serviceability problems (SLS) or even pile failure (ULS), as that soil squeezes between and around the piles. When modelling such phenomena one should consider the nonlinear material behaviour, as well as the complex nonlinear deformation and contact processes imposed by the horizontally moving ground. The objective of this paper is to give recommendations for estimating passive loads on piles based on numerical simulations, using the visco-plastic material model of Zienkiewicz & Godbole (1974). Additionally, experimental and numerical results of a back analysis of a sophisticated large scale test for the design of a piled foundation of a runway next to a steel yard on alluvium soil in Brazil are presented. Both allow a better understanding of the state of stresses and displacements in the near-field of the piles, as well as a comprehensive understanding of soil-pile interaction; i.e. flow of soil around the pile.