ANALYSIS OF VIBRATION CAUSED BY PASSING TRAINS IN SUBWAY OVERLAPPING RUNNING TUNNELS WITH SEVERAL TYPES OF CROSS-SECTIONS

The vibration loads caused by passing trains was established from a wheel-track model. According to a subway project, three shapes of cross-sections, a single-tunnel section with two tubes of double-layer partition, a single-tunnel section with two tubes of single-layer partition and a double-tunnel section, were adopted respectively to simulate the process of the tunnel construction and obtain the static stress field. The FEM models for the three types of tunnels were established to study the dynamic behaviour of the tunnel-mass systems. The dynamic responses of the subway tunnels to the vibration caused by trains running in the upper tube, the lower tube and both tubes at the same time, were Studied with Newmark implicit time integration method. The results indicated that, compared to the static stresses, the lining stresses produced by trains vibration loads played a less leading role at the top of lining, but they were prominent at the feet of the invert arch and the interface of the wall and the partition. The displacements caused by passing trains on the lining partitions were not very big, and could meet the requirements of subway design.