Study on the Interaction of Metro Shield Tunnel Construction Under-Crossing the Existing Longhai Railway

Based on the construction of Zhengzhou Metro Line 4 (Huozhan Street Station–Hanghai East Road Station) under-crossing Longhai Railway, this paper investigated the interaction between railway train operation and shield tunneling. A three-dimensional coupled finite element model of track-roadbed-soil, using the finite element software MIDAS/GTS NX, was established to simulate the stages of the shield tunnel construction and analyze the influence on the existing railway. During different stages of the shield tunnel construction, the ground subsidence caused by the passing of single train was analyzed by simplifying the train loads as vibration loads, and the numerical simulation results were compared with the field monitoring data. The results show that: (1) the maximum settlement of the railway is about 3.39 mm without train passing, which is less than the control standard range of 6 mm, and so the shield tunnel construction can ensure the normal operation of the upper railway; (2) vehicle-induced vibration will lead to additional subsidence of the railway, which is only 0.20 mm when the upper train has the speed of 160 km/h, so the total settlement is 3.59 mm, which is also less than the control standard range of 6 mm. In conclusion, the upper train doesn’t need to be limited with velocity in the process of shield tunnel construction.