Research And Numerical Simulation On Longitudinal Anti-seismic Performance Of Shield Tunnel

Shield tunnel is one of the important lifeline engineering, so the research on its seismic safety has significant influence. Therefore, the research on the anti-seismic performance of shield tunnel is facing a serious shortage, especially on longitudinal. People have gradually realized the limitation of seismic coefficient method that was recommended by relevant standards, when analyzing the seismic response on underground structure. However the seismic deformation method and the dynamic finite element method are considered to be preferable.In this dissertation, elastic foundation model is adopted to simulate the characteristic of shield tunnel, and a longitudinal continuous equivalent model is established. Taking a river-crossing shield tunnel as an example, the seismic deformation method and the dynamic finite element method are used to calculate the maximum tensile stresses of shield segment and longitudinal connecting bolt under7degree earthquake. Hence, some conclusions are obtained.(1) This dissertation recommends that while calculating the maximum stress of shield tunnel, the whole cross section tensile state can be taken into consideration, with the ignorance of part tensile state. Modified equivalent continuous model of longitudinal rigidity of shield tunnel was built based on the longitudinal equivalent continuous model built by Shiba Yukio, with the influence of axial force taken under consideration. A continuous equivalent model with the whole cross section under tensile state is built based on the modified equivalent continuous model. The equivalent elastic flexural rigidity calculated in this dissertation is1/10of universal tunnel, which is1/15calculated by Shiba Yukio and1/5measured by Zang xiaolong. The result shows that the equivalent elastic flexural rigidity in this dissertation is more approximates to reality than the one built by Shiba Yukio. (2) This dissertation recommends that shield tunnel enters plastic stage after the longitudinal connecting plots are under plastic stage. And a calculation formula for axial force under plastic stage caused by earthquake is built.(3) A river-cross shield tunnel is taken as example for longitudinal continuous equivalent finite element model to calculate the anti-seismic performance of shield tunnel and compare with the theoretical analysis result, in order to verify the reliability theoretical analysis result.