Seismic performance of large shield tunnel considering internal structure
WANG Wei1, LIU Ying1, ZHUANG Haiyang1, 2*, ZHAO Kai1, CHEN Guoxing1
(1. Institute of Geotechnical Engineering, Nanjing Tech University, Nanjing 211816, China; 2. School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China)
Abstract: Taking the GIL shield tunnel integrated corridor as an example, the non-linear soil-tunnel structure with and without the π-shaped bracket structure was established as a three-dimensional finite element analysis model for static and dynamic coupling, and the effect of the π-shaped bracket structure on the overall seismic performance of the shield tunnel considering staggered assembly was investigated. The results showed that the tube sheet tension at the bottom of the tunnel was significantly reduced by up to 60% after the π-shaped bracket structure was placed, and the tube sheet tension near the capping block tended to increase under large earthquakes. The acceleration response spectra at the top and bottom of the tunnel and at the π-frame structure-tunnel connection do not change significantly when the input ground shaking peak was small; as the input ground shaking peak increases, the response spectra fluctuate significantly within short periods and the overall response spectra values decrease. On the whole, the tensile damage to the concrete at the top of the tunnel structure was aggravated, while the tensile damage at the bottom was relatively light, and the tensile damage was mainly distributed at and around the tube joints. It was necessary to consider the effect of the tunnel-π-shaped support structure dynamic interaction in the seismic design of large diameter shield tunnels.
