| Metro construction in China is divided into tunnel construction and metro platform construction.Shield method is the main method for tunnel construction,while open-cut method and mining method are the main methods for metro platform construction.It is difficult to give full play to the advantages of shield construction in the construction process,which also reduces the efficiency of subway construction.Based on the construction idea of shield tunneling method for metro platform abroad,shield method was proposed for metro platform with good self-stability in geological surrounding rock,but without the help of segment lining.The segment-free propulsion of shield tunneling was studied,and the scheme design of shield auxiliary propulsion device was completed.Then the finite element analysis and lightweight design of the device were carried out.Besides,the assembly sequence of the device in the tunnel was planned by genetic algorithm.The main contents of this paper are as follows.1.In view of the subway platform construction with better self-stability of surrounding rock,the shield tunneling without segment is proposed,and the scheme design of shield auxiliary propulsion device is completed.Based on the design scheme,the working principle and components of the device were briefly introduced.Based on the geological parameters of a metro platform in Guangzhou,the device type selection and parameter calculation were carried out.2.Based on the geological analysis of subway platform,three calculation conditions of shield auxiliary propulsion device were determined.Based on ANSYS software,the mechanical properties of key structures such as connecting column components and boot structure were analyzed under three kinds of calculation conditions.Based on the results of finite element analysis,the most dangerous calculation conditions were determined,and the suggestions for improving the structure with stress concentration were put forward.3.Based on the most dangerous calculation condition,the lightweight design of boot structure was carried out by using ANSYS software.The contradiction between the number of steel plates to be lightened and the upper limit of the number of software design variables is solved by using the idea of grouping and phasing lightweight.Compared with the originalstructure,the weight of lightweight boot bracket structure was reduced by 19.7t,and the weight loss ratio was 16.7%.Based on the lightweight results,the steel plate set with the largest proportion of weight reduction was determined.The mechanical properties of the lightweight structure were analyzed,and the relevant lightweight suggestions were given.4.Based on genetic algorithm,the assembly sequence of the device in the tunnel was planned by using MATLAB software.The matrix APRS meaning priority constrained stability between assembly parts was established,and high quality initial population was obtained based on the matrix.Symbolic encoding was used and genetic operator was selected by referring to TSP problem.The evaluation index system of assembly sequence was established,and the TOPSIS evaluation algorithm based on entropy weight was used to design the fitness function.A reasonable combination of genetic operators was obtained by trial calculation of the value of genetic operators.The results showed that the initial population generated by matrix A PRS can greatly improve the convergence speed of the algorithm.And based on the initial population generated by matrix APRS,the optimal assembly sequence of the device in the tunnel was obtained. |
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