Vertical responses of capped pile foundations to ground movements induced by tunneling

A simplified method of numerical analysis is developed to estimate the settlement and load distribution of capped pile foundations subjected to ground movements induced by tunneling in layered soil based on a two-stage method. In this method, the Loganathan analytical solution is used to estimate the free-field ground movements induced by tunneling at the first stage. At the second stage, composing the ground movement to the pile, the vertical movements governing equilibrium equations of piles are solved by finite difference method. The interactions between structural members, pile-soil, pile-raft, raft-soil and pile-pile interactions are modeled by means of the method in layered elastic half space though in case study there’s no need to consider the raft-soil interaction. The validity of the proposed method is verified through comparisons with centrifuge tests, some published solutions for a single pile, pile groups and pile rafts subjected to ground movements induced by tunneling. Good agreements between these solutions are demonstrated. Responses of passive piles in layered soils and reduction of pile-soil interaction by pile deformation are analyzed.