Research On The Seismic Response Of Immersed Tunnel With Simplified Calculation

With the development of economy and modern transportation construction in our country,many large-scale subsea tunnels,such as cross-channel project over Qiongzhou strait and Hongkong-Zhuhai-Macao immersed tube tunnel project have been built or under constructionplanning.There may exist some high seismic intensity areas in which these engineering arebuilt,so sufficient attention has to been paid to the investigation on their seismic behaviors.Nowadays,in the research on seismic behavior of subsea tunnel structure,the use of three-dimensional solid model in calculation can be closer to the actual situation,but the use of this model requires the finite element software,artificial modeling workload is large,and its calculation process and result data processing are more complex.It is very necessary to establish a large immersed tunnel model quickly and easily and to extract and process a large number of result data in a targeted and efficient manner.This paper relies on a large underwater immersed tunnel project,combined with the immersed tunnel earthquake resistance theory,based on the ABAQUS finite element software embedded Python script language and pre-processing interface for the secondary development of ABAQUS.The integral finite element model of the immersed tunnel was established,and the influence of the hydrodynamic pressure was considered.The influence of the non-uniform excitation of the ground motion and the input direction of different earthquakes on the structural dynamic response of the immersed tunnel was studied.The main work of this paper as follows:(1)Sums up and summarizes the common analysis models and analysis methods of the longitudinal seismic calculation of immersed tunnel,compares with the characteristics and conditions of immersed tunnel,selectes the suitable analysis models and methods which suitable for this project.(2)After the secondary development of the ABAQUS software pre-processing and post-processing,according to the actual situation of an immersed tunnel,the ABAQUS pre-processing was firstly used for secondary development using Matlab,and the overall finite element model of the immersed tunnel was programmed to be established and analyzed.However,the secondary development of ABAQUS post-processing was done in Python,and a large number of calculations after the analysis of the immersed tunnel were processed.Designed to provide reference and help for the procedural modeling and analysis of long immersed tunnels.(3)Relies on a large underwater immersed tunnel project,an approximate two-dimensional model of the cross-section of the ground soil and structure is taken and the relevant parameters are input.Under the premise of relevant assumptions,using the ABAQUS software to calculate the stiffness of the foundation spring at different cross-sections.(4)Using ANSYS/LS-DYNA software,builds the three dimensional finite element models of soil in tunnel,analyzes the displacement time history response of soil,gives the displacement response to the longitudinal beam-spring model of shield tunnel by the stratum spring.(5)Using response displacement method to calculate the seismic response of the structure of the approximate model of immersed tunnel,and the immersed tunnel is subjected to the consideration of hydrodynamic pressure,non-uniform excitation of ground motion,and the overall longitudinal seismic response under different earthquakes.