Vertical Load Effects on the Lateral Response of Piles in Layered Media

Abstract

This paper presents and discusses the results of a three-dimensional numerical study performed to evaluate the effects of vertical loads on the response of laterally loaded piles in both homogeneous and layered soils. Piles were treated as linear elastic materials, whereas soils were idealized using the Mohr-Coulomb constitutive model with a nonassociated flow rule. Vertical loads, corresponding to several percentages of the ultimate pile load, were imposed prior to the application of lateral loads. In a homogeneous sandy soil, numerical results showed that the lateral resistance of the pile did not vary considerably with vertical loads. However, the presence of vertical loads on a pile embedded in clayey soil was found to be detrimental to its lateral capacity, and it is unconservative to design piles in clays assuming there is no interaction between vertical and lateral loads. In layered soil media, which is the main part of the current study, it was found that the effect of vertical loads depends on not only the characteristics of soil surrounding the piles but also those located beneath their tips.