FEA Of Double-row Piles Considering The Dimension Effects

A finite element model considering the pile-soil interaction and the dimension effect of retaining structure is proposed in this paper. In this model,the finite element software Abaqus is used ,and soil nonlinearity is modeled using Modified Cam-clay constitutive relationship. The lateral deformation and the moment of the pile at any point can be calculated with this model.Some factors which have influences to the internal stress and deformation of the retaining structure are analyzed , such as the dimension effect of retaining structure(mainly the pile distance and the width of excavation),the pile stiffness,the soil quality,the array pitch of the front pile and the rear pile and the reinforcement of the passive domain soil. The stress characters of the double-row piles of retaining structure are summarized comparing of the analysis results, and some reference results are summarized for engineering practice and theory study.The main conclusions are the following:1. The lateral deformation are not too much with the increase of the pile distance. The pile distance of (2～2.5)d(d is the diameter of the pile) are suggested to be used when there is no strict restrictions to the lateral deformation.2. The influence of width of excavation is remarkable to the lateral deformation.This may be attributed to a larger zone of plastic deformation of soil taking place for a wider excavation and it should be considered carefully.3. The double-row piles retaining structure is similar to the cantilever single-row pile when the array pitch is small. But when the array pitch is large, the rear pile behaves like an anchor to the front pile .Generally speaking, the displacement is smaller as the increase of the array pitch and the array pitch of (3～6)d(d is the diameter of the pile) is suggested considering the total factors.Some project cases are analysed using the method of this paper. The rationality and the applicability of the model are validated.