On deformation of bridge pile foundations adjacent to excavations

Abstract

The unloading effect of excavations can cause a change in the stress field and displacement field of surrounding strata, which may seriously influence the existing bridge pile foundations adjacent to excavations. Based on a foundation pit excavation in Kunshan, Jiangsu Province, the finite element method considering the small strain of soil is adopted to study behavior of the excavation and its influence on deformation of the nearby pile foundations. The major calculation parameters of HS-Small model are determined to well describe the deformation characteristics of the soil. Through numerical calculation and simplified analysis, the influence zones for deformation of bridge pile foundations adjacent to the excavation are divided into three types, considering various deformation controlling criteria for existing pile foundations as well as the relative spatial relationship of the pile foundation and the excavation. Dividing lines between these types of zones are the allowable displacement line and the warning displacement line. Accordingly, the adjacent piles are divided into three types. During the construction of foundation pit, it is useful to take corresponding measures depending on which influence zone that the bridge pile foundations in.