Improvement Of Integral Forced Response Displacement Method And Its Application In The Seismic Analysis Of Shield Tunnel

With the rapid development of underground engineering at home and abroad,the seismic problems of underground structures have received more and more attention.it has become a concern for scholars at home and abroad to explore an easy-to-operate and applicable seismic method for underground structures.Based on the integral forced response displacement method proposed by Chen Zhiyi and others,this paper studies the applicability of this method in the seismic analysis of shield tunnel structure,and puts forward the improvement methods for the defects of this method.The main contents and achievement are below:Taking an underground shield tunnel in Tianjin as an example,this paper adopts the integral forced response displacement method to analyze and calculate the seismic analysis of subway shield tunnel structure.In order to verify the applicability of this method in seismic analysis of shield tunnel structures under the complex soft soil field,the internal force diagram and internal force peaks of the shield tunnel are calculated by three methods including the integral forced response displacement method,the response displacement method and the time-history analysis method,and the results are compared and analyzed on the basis of the results of the time-history analysis method.The results show that the integral forced response displacement method has better applicability when it is applied to the seismic analysis of shield tunnel structure in complex soft soil site.Compared with the response displacement method,the integral forced response displacement method has great advantages in Computation accuracy and facilitating the initial stress caused by the permanent load.The calculated deviation of the integral response displacement method comes from the fact that the influence of underground structure is not considered in the process of equivalent seismic load,and the whole seismic time history is difficult to be considered in the process of quasi-static force.In view of the defect of the integral forced response displacement method,the forced displacement of the integral forced response displacement method is improved by the free field displacement correction value,and the method is verified by the homogeneous field.In order to verify the applicability of the improved method in practical engineering,the internal force peak,the diameter change rate and joint opening amount of the shield tunnel are calculated by three methods including the integral forced response displacement method,the improved integral forced response displacement method and the time-history analysis method,and the results are compared and analyzed.The results show that in the three aspects of peak value of internal force,diameter change rate and joint opening of shield tunnel,the computational results of the improved integral forced response displacement method is closer to the calculated results of time history analysis method,and the improved effect is good.This method can be used as a reference for seismic design of engineering.In the aspect of the internal force peak of the shield tunnel,the improved method has a good effect on the bending moment and shear force peak of the shield tunnel,but the improved effect on the axial force peak of the shield tunnel is not obvious.