SEISMIC RESPONSES OF LARGE SECTION TUNNEL BASED ON SHAKING TABLE MODEL TEST

This paper is based on the enlargement project of Jinjishan Tunnel in Fuzhou 2nd ring road. A 1/30 downscale model for the large section tunnel is fabricated. The earthquake-simulating tests with 21 loading cases are carried out. The seismic responses of acceleration and normal pressure upon the tunnel model are focused. The PGA amplification coefficient is defined as the ratio between peak seismic acceleration and peak ground acceleration. The PGA amplification coefficients upon tunnel model increase logarithmically with ground elevation. The ground elevation effect distinguishes from other regular grounds. With the augment of ground motion amplitude, the PGA amplification coefficients upon tunnel model decrease gradually, and the influence of frequency characteristic on the ground elevation effect vanishes gradually. The PEP oscillation coefficient is defined as the ratio between peak seismic and static normal pressures. With the augment of ground motion amplitude, the PEP oscillation coefficients upon sidewall and arch increase linearly in general, while the PEP oscillation coefficients upon crown and invert always remain in a small range. In the aseismic design of larger section tunnel, these results can provide some reference to the evaluation of contact pressure between the lining and the ground.