Abstract:
A large number of China's large shield tunnel project is located in strong earthquake area so it is very necessary to study the seismic response of large shield tunnel under earthquake. As far as the crossing-river shield tunnel built in Sanyang road, Wuhan city was concerned, a two-dimensional numerical model of nonlinear tunnel free field of the shield and shield tunnel overall fine longitudinal beam spring model were built. Opening value between ring intersegments along the longitudinal was studied in the different intensity and different spectrum characteristics of earthquake motion. Results demonstrate that the shield tunnel adjacent opening value extreme along the longitudinal trend has similarity under different conditions, and opening value extreme increases nonlinear with the increase of intensity in the same earthquake motion. The seismic frequency spectrum has great influence on the longitudinal seismic response of the tunnel, and the opening value extreme exhibits high frequency reduction and low frequency amplification. In the sand layer and the bedrock surface at the junction, the opening value shows the phenomenon of abnormal mutation. In the Darfield wave, PGA=0.4 conditions, the local position exceeds the general waterproof measures to allow the opening limit. The calculation results provide a reference for the longitudinal seismic design of shield tunnel structure.