Pile Groups Subjected to Axial and Torsional Loads in Flow-Controlled Geomaterial

Abstract

The pile groups were used as a foundation for complex structures experiencing large axial, lateral, and torsional loads. As a result, they undergo vertical, lateral, and eccentric movements. Moreover, there were several studies on piles and pile groups under axial and lateral loads, but the solutions for pile groups subjected to combined axial and torsional loads were largely elusive. Therefore, a novel numerical scheme was presented to capture the nonlinear pile–soil interaction in a flow-controlled geomaterial to make allowance for the yield effects. Based on the numerical scheme, a three-dimensional finite-element analysis was performed on pile groups subjected to combined axial and torsional loads in the flow-controlled geomaterial using a computational program. The flow potential for the yield surface of the flow-controlled geomaterial is a hyperbolic function of stresses in the meridional stress plane and the smooth elliptic function in the deviatoric stress plane. The load–displacement relationship of a large diameter pile (LDP) and pile groups (1,2 and 2,2) was compared with the experimental pile load test and the numerical results reported in the literature. It was observed that the resultant displacement increases significantly with the torsional load for the LDP and pile groups. Similarly, the twist increases significantly with an increase in the axial load. The displacement and twist parameters were classified based on the plastic strain and dilation angle of the geomaterial.