Impact of orthogonal lateral loading on the ultimate lateral pile load capacity and lateral flow characteristics of a modeled pile

Past studies have predominantly examined the effects of unidirectional lateral loading on piles, establishing
comprehensive design guidelines. However, real-world lateral loads on pile foundations often exhibit
multidirectional characteristics. This study investigates the behavior of a modeled single pile subjected to loads applied in two orthogonal directions, focusing on the influence of varying loading levels in the x-direction on the pile’s subsequent response to y-direction loading. A custom-built bi-directional lateral loading apparatus was developed to independently apply loads in the x and y directions, enabling lateral loading along diverse paths. Increasing the lateral preloading level in the x-direction reduces the ultimate lateral pile load capacity under subsequent y-direction loading. Furthermore, increasing the load in the y-direction while maintaining the xdirection load constant causes deviations in the pile’s flow characteristics from the y-direction, with these deviations decreasing as the y-direction load increases. These findings suggest that accurately predicting lateral deformation and ultimate lateral pile load capacity under bi-directional loading requires accounting for preloading history and levels.