The seismic responses and seismic properties of large section mountain tunnel based on shaking table tests

摘要

Based on the engineering prototype of new Jinjishan Tunnel in Fuzhou 2nd ring road, the 1/30 downscale ground-lining model was fabricated. Then the earthquake-simulating tests were carried out on the shaking table apparatus to explore the seismic responses and seismic properties of large section mountain tunnel. The time-domain analyses on the test results show that the PHA (peak horizontal acceleration) amplification coefficients of ground increase non-linearly with elevation. The elevation effect of ground takes "S" form, which distinguishes itself from other regular ones. The PCP (peak contact pressure) oscillation coefficients at the sidewall and the arch of lining increase almost linearly with the seismic intensity, which implies that the sidewall and arch carry a majority of seismic loading under large ground motion excitation. The frequency-domain analyses on the test results show that the existence of large section tunnel changes the seismic property of original ground significantly. The 1st and 2nd dominant frequencies reflect the seismic properties of original ground and lining structure respectively, and both of them decrease gradually with the repeated excitations. Meanwhile the frequency components around the 2nd dominant frequency are augmented significantly when the seismic wave passing through the model from bottom to surface.