Experimental investigation of shield-driven tunnel crossing soil-rock interface under longitudinal excitations
Guo Zhiming1 Li Siming2 Yuan Yong2,3 Xue Guangqiao4
1. Public Works Construction Center, Nanjing 210019, China;
2. College of Civil Engineering, Tongji University, Shanghai 200092, China;
3. State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China;
4. China Railway Siyuan Survey and Design Group Co.，Ltd., Wuhan 430063, China
Abstract：The discrepant responses of a shield-driven tunnel crossing a soil-rock interface are of interest to engineering construction. In this study, a shaking table test was carried out with the geometry similitude ratio of 1∶25. The model soil and model rock were fabricated by considering the dynamic character similarity. According to the equivalent longitudinal stiffness principle, tunnel model rings containing joints were manufactured. A series of synthetic earthquake motions were input from the table, and the vibration direction was parallel to the tunnel axis. The acceleration of the tunnel model, the sectional deformation, and the extension of joints were observed during the shield tunnel model test. The discrepant responses of the tunnel buried in the soil and rock strata were revealed by the transfer function of the acceleration data. The test results indicate that the tunnel in the rock stratum only has translational displacements parallel to the shaking direction. Thus, the joint extension values and the cross-sectional deformation of the tunnel in rock are negligible. The tunnel in soft soil mainly deforms by longitudinal tension and vertical bending. The maximum extension of the joint is located at the soil-rock interface, and should be considered in seismic design. The cross-sectional deformation values of the tunnel are limited, and the sectional deformation is prevailing in the horizontal and vertical directions.
