Ovaling deformations of circular urban tunnels under seismic wave propagation

The urban tunnels under severe earthquake excitations are very important lifelines because of the number of facilities and the beneficiaries in progressive countries. Historically, underground facilities have experienced a lower rate of damage than surface structures. Nevertheles some underground structures have experienced significant damage in recent large earthquakes, including the 1995 Kobe, Japan earthquake, the 1999 Chi-Chi, Taiwan earthquake and the 1999 Kocaeli, Turkey earthquake.In This study the analytical solutions for the thrust and moment in the lining of a circular tunnel due to seismic induced ovaling deformation Is considered . The discrepancy among the existing solutions in the thrust and moment for interface with Different conditions is investigated . The analytical solutions are compared to numerical analyses using finite element method with Plaxis to validate which of the solutions providethe correct solution.The three circular tunnels with different thickness for finite element modeling have been developed .Comparison of the solution methods shows that the calculated forces and displacements are identical for the condition of full slip between the tunnel lining and ground. However, the calculated lining thrusts differ by an order of magnitude when assuming no-slip between the tunnel lining and the ground.

Keywords:

Ovaling deformation , seismic loading tunnel wave propagation