Dynamic Response Characteristics of Joint between Working Shaft and Tunnel under Train Vibration Loads

The Shi Ziyang tunnel is the first underwater tunnel for high speed railways in China. It is constructed by the open cut method and shield method. The joint between the working shaft and two side tunnels (shield tunnel and open cut tunnel) is a special space crossing structure, and dynamic response characteristics of the joint are quite complicated under train vibration loads. Therefore, a three dimensional numerical model of the joint is established. Vibrating response analysis on the complicated structure under train loads is conducted with FLAC3D. The displacement and stress response rule of key points in the joint are obtained. In the process of train loads excitation, vertical and horizontal convergence displacement of the joint between the working shaft and open cut tunnel are respectively 0.402mm and 0.109mm, and vertical and horizontal convergence displacement of the joint between the working shaft and shield tunnel are respectively 0.293mm and 0.235mm. Peak values of tensile stress and compressive stress of all key points are all less than the strength design value of concrete. Thus, in further analysis, which is presented here, the joint has a better anti-vibration ability. The research results have important reference value not only on the dynamic stability evaluation of tunnel structures but also on the tunnel construction design of high speed railways.