| Underground structures,especially tunnels,once are damaged by an earthquake,not only the underground traffic will be paralyzed,but the ground to collapse also may be caused,which will affect the safety of the traffic and buildings on the ground seriously.Therefore,in order to ensure safety enough of the shield tunnel under earthquake action,it is very important to perform seismic response analysis in advance.In this thesis,based on a large-diameter shield tunnel project,a longitudinal equivalent continuous finite element model is established in the nonlinear analysis software TDAPIII.Using the principle of series connection and cooperative deformation between the segment and the ring,the segment ring of the tunnel is simplified as an equivalent stiffness beam.Based on the response displacement method,forced displacement is applied at the far end of the foundation spring.Considering the influence of traveling wave effect,the internal force and deformation of shield tunnel under the earthquake are analyzed and the three-wave average response value is used to evaluate the performance index of shield tunnel.The main work and conclusions are as follows:(1)After defining the applicability of equivalent continuum model and TDAPIII finite element software in establishing the shield tunnel model,it is determined to combine the response displacement method with TDAPIII finite element software by comparing various quasi-static analysis methods.Based on the response displacement method,a simplified longitudinal equivalent continuum model was established,including the soil-structure interaction simulated by the foundation spring,the equivalent stiffness beam simulation segment,and the connection bolt simulated by the equivalent spring.(2)Considering the traveling wave effect or not,the forced displacement is applied to the ground spring in both longitudinal and transverse directions.Combined with the complexity of foundation soil and the asymmetry of tunnel structure,each direction is divided into two input modes: from left to right and from right to left respectively.The differences of axial force,shear force,bending moment and opening amount of connecting bolt in different tunnel materials are analyzed,and the effects of travelingwave effect and segment stiffness are analyzed.(3)The main performance indexes of shield tunnel are evaluated by using the seismic performance evaluation method based on the three-wave average structural response.The results show that the overall seismic performance of the shield tunnel structure is good and meets the main performance requirements.The evaluation takes into account the economy and provides an important reference for the subsequent seismic design work.(4)There is a great difference between the internal force and the displacement of shield tunnel without considering the traveling wave effect,which indicates that the traveling wave effect has a great effect on the shield tunnel.The seismic response of different stiffness segments is different,especially in the connection part of the two kinds of rigid segments,it is easy to destroy because of the sudden change of internal force and displacement.(5)For shield tunnel with different stiffness segments,it is very important to analyze the seismic performance of shield tunnel,but it is also necessary to take into account the efficiency.The longitudinal equivalent continuum model of shield tunnel can simplify the model to a great extent.It can also reflect the internal force and opening of each structural segment and connecting bolt in detail.In this study,the response displacement method is combined with the finite element theory in consideration of the traveling wave effect,and the seismic performance evaluation method based on the three-wave average structural response is applied,which has good practicability in the research of the seismic performance of shield tunnel. |
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