Longitudinal Seismic Response of Large Sectional Shield Tunnel

摘要

In this paper,seismic deformation method is applied to analysis the longitudinal seismic re -sponse of the shield tunnel for r the specific project across Yangtze River in Nanjing. The shield tunnel is simplified to a line beam to establish equivalent r continuous model , which has the same longitudinal deformation with the shield tunnel. The axial force and bending moment are r simultaneously considered in calculating and the pre-stress of bolts is also considered. According to the impact of the r inputting angle and the level of strong motion , inputting is divided into the following cases : inputting by PGV=r 0.15m/s(equivalent to 7 degrees seismic fortification intensity)and PGV=0.30m/s(equivalent to 8 degrees seismic r fortification intensity) ,incident angles are respectively 0° ,30° ,45° ,60°. Then,the results by seismic deformation r method are compared with that by the 3-D finite element method ,and the similar results can be obtained. The results indicate r that: (1) Seismic deformation method is a simple and practical tool for engineering application ,e. g. for longitudinal r seismic response analysis of large sectional shield tunnel;(2) Amount of joint opening is directly obtained by seismic r deformation meth -od,as an important parameter for the anti-seismic design of shield tunnel,which is recommended as a dynamic r indicator for evaluation and control of structure response during large earthquake occurring ; (3)Incident angle and level of r inputting strong motion (acceleration, velocity and displacement)have an important effect on longitudinal seismic analysis r ,the most unfavorable load case should be selected as a control condition for design and study of engineering.