Analysis on Disturbance Law and Pile Barrier Effect of Shield Crossing Underground Structures in Composite Strata

Abstract:

Based on a shield tunnel project that simultaneously crosses multiple piles and existing tunnels， a numerical model was built and verified. The laws of surface settlement， convergence of existing tunnels and pile deformation induced by shield tunneling were summarized via the simulation. In addition， the barrier effect of piles on the transmission of disturbance was highlighted. The pile-soil-tunnel interaction mechanism was also revealed with the analysis of stress path of soils. The results show that the existence of pile foundation reduces the surface settlement and the width of settlement trough induced by shield tunneling， and changes the deformation mode of the existing tunnels. All these differences indicate that the pile has obvious barrier effect on the transmission of disturbance. A large lateral displacement occurs at the top part of piles and the lateral inclination of the pile cap undergoes complex trends， which is the results of the existing tunnel and shield tunneling process. The stiffness difference among piles， tunnels and soils is the basic reason for pile-soil-tunnel interactions.

Key words:shield-crossing;composite strata;piles;barrier effect;numerical simulation