Research On Structure Optimization And Control Technology Of Soft Rock Large Deformation Tunnel

Taking haizishan tunnel on Shi Qu to mani wars highway as project background,this paper discusses the large deformation problems during the construction of the weak geological section of haizishan tunnel by means of theoretical analysis,numerical simulation and field monitoring,and studies the construction method,supporting parameters and construction control measures of the large deformation tunnel section.The main research results are as following:(1)The deformation mechanism and types of large deformation of soft rock tunnel are discussed,and analyzes the main causes of large deformation in the construction process combined with practical engineering,and studies the control technology theory and method of large deformation of soft rock tunnel.(2)According to the project geological condition,a three-dimensional numerical model is established,using the finite element software respectively on two steps method,core making,CRD method and so on three different construction methods for the numerical simulation of the vertical displacement of the tunnel vault under three kinds of methods and sidewall horizontal displacement law of development,by the results of numerical simulation and considering construction convenient to select two step method for the optimal construction methods of the tunnel.(3)Combined with the characteristics and mechanism of supporting structure of soft rock tunnel,finite element software is used to discuss the influence of different shotcrete strength and thickness,different bolt transverse spacing and length on the stability of surrounding rock,the optimal supporting parameters and the reasonable secondary lining thicknesses of this tunnel are obtained.(4)The advantages and disadvantages of the technique of controlling the first displacement and the second displacement of the palm face are studied and analyzed.(5)Combined with the field monitoring data,comparative analysis of the numerical simulation is conducted to verify the reliability of the numerical simulation analysis and provide a theoretical basis for the design and construction of similar projects in the future.