Effect of Vertical Load on Lateral Behavior of Pile in Clay

Abstract

The influence of vertical load on the lateral stiffness and capacity of the pile is merely considered in the current design practice and therefore deserve a further investigation. This study presents detailed centrifuge tests results on the lateral behavior of a single pile in normal (NC) and over consolidated clay (OC), with and without application of vertical loading at the pile head. In the meantime, three-dimensional finite element analyses (FEA) were carried out to offer further insights into the effect mechanism of vertical loads on lateral pile behavior. Both physical and numerical investigation reveal that after applying the vertical load and allowing the dissipation of excess pore pressure in NC, the stress ratio (q/p’) of the soil around the pile decreases while the mobilisable undrained shear strength (s_u) increases, resulting in 10% and 50% increase of the lateral initial stiffness and bearing capacity of the pile, respectively. In contrast, due to application of vertical load to a single pile in the over consolidated clay, the q/p’ prior to lateral loading increases while the mobilisable s_u decreases, consequently leading to 13% and 33% reduction of the lateral initial stiffness and bearing capacity of the pile, respectively.