The Study Of Construction Methods For Big-span Expressway Tunnelin Soft Ground-The Numerical Simulation And Field Measurement Of Three Step Method

In this paper,the author makes a study on the three step method of tunnel excavation by using the method of integrated test,numerical analysis and practical theory:(1)the strength of surrounding rock is measured by point load meter.Determine the quality index of rock mass,determine the groundwater flow and structure area.Study on the quality of the surrounding rock in the initial state,and constantly adjust,to ensure that the surrounding rock correction is based on the classification of the surrounding rock,to complete the spot load and acoustic wave test,based on the results of the classification of the surrounding rock.(2)consider the side heading excavation method,three step method and two working conditions,established the simulation model of finite element numerical simulation,complete finite element numerical soft rock roadway excavation.The finite element numerical simulation results show that the deformation of surrounding rock is small and the stability of surrounding rock is good.(3)the final construction of the soft rock tunnel construction supervision and quality inspection.The results show that the numerical simulation results are consistent with the finite element numerical simulation of the surrounding rock deformation.The three step construction method is reasonable.