Drag Force on Single Piles in Clay Subjected to Surcharge Loading

Abstract

Piles driven into clay are often subjected to indirect loading as a result of the surcharge applied on the surrounding area. During the drained period, both the piles and the soil undergo downward movements caused by the axial and the surcharge loading, respectively. Depending on the relative movement of the pile–soil system, positive and negative skin friction develop on the pile’s shaft. Negative skin friction is the drag force that may be large enough to reduce the pile capacity and/or to overstress the pile’s material causing fractures or perhaps structural failure of the pile, and/or possibly pulling out the pile from the cap. A numerical model that uses the finite element technique combined with the soil responses according to Mohr–Coulomb criteria was developed for case simulation. The computer program CRISP (developed by Cambridge University) was used in this study. The numerical model was first tested against the results predicted by the bearing capacity theories for pile foundations in clay subj...