A Numeical Investigation Into The Impact Of Tunneling On Piles

Subway tunnels are frequently constructed in locations close to the existing pile foundations. The tunneling causes ground soil movements , which in turn are impact on the adjacent pile foundation. However, the actual impact of tunnel construction on pile is not very understood.The numerical tests are used in this paper to study the deformation features of the ground soil and pile caused by tunneling near the driven pile via the software FINAL. It is considered in the numerical tests with the soil parameters E_s, pile parameters E_P, pile length, and the distance between pile and tunnel. The influence of pile positions to ground settlement induced by tunneling is studied, and the soil around the tunnel is divided into four zone A, B, C and D. then the influence of the different zone on pile displacement is discussed . Then for three typical locations of the double-pile, the influence of tunneling is researched, and the comparison is done between single pile and double-pile. And the main results involve four parts:1) Based on the deformation features of the ground soil caused by tunneling, the surround soil of the tunnel is classified into fours different zones: A,B,C and D .In the A zone, the same settlements simultaneously happen to the pile and nearby soil. In the B zone, the settlement of the pile is the largest. In the C zone, the settlement is the same as that of B zone. In the D zone, the tunneling has few effect on the settlement of the pile.2) The bearing of the friction-pile located in the A zone and B zone is reduced, bytunneling ,and the most decreases happen to the B zone. The stresses of piles located D zone are obviously increased.