| This article takes the Shaofang Yakou Tunnel as the engineering background,aiming at the frequent occurrence of geological hazards during the construction of long and large tunnels in complex geological conditions and special environments during the rainy season.Based on a large number of references,a summary of the fault structure fracture zone Genesis and structural characteristics,the factors influencing the stability of the surrounding rock of the tunnel excavation in the Shaofang Yakou fault structural fracture zone are proposed.By analyzing the numerical simulation results,the safety warning distance of the tunnel face from the bad geological body of the fault structure fracture zone is proposed,and the optimal grouting ring thickness of the tunnel construction under the high water and rainy season environment is proposed according to the tunnel plastic zone range optimization.The main research results obtained are as follows:(1)On the basis of the research status of the stability of tunnel excavation of a large number of fault structure fracture zones and the research status of the advance reinforcement technology of the tunnel fault structure fracture zone,the current factors affecting the stability of the tunnel surrounding rock and the tunnel are summarized The method and effect of the advance reinforcement technology have a clear and comprehensive understanding of the current stability factors affecting tunnel excavation and the advance reinforcement technology of the tunnel.(2)According to the fine survey of the geological conditions of the fractured zone of the Shaofang Yakou fault structure and the physical and chemical characteristics of the sandstone water in the fractured zone of the Shaofang Yakou tunnel,the micro structure test(environmental electron microscope test)was adopted to break the fault structure The microscopic analysis of the sample with rock mass is carried out to obtain its water physical and chemical characteristics.The test results provide a basis for analyzing the deformation of the surrounding rock and the safety warning distance when the deep and long tunnel passes through the fault structurefracture zone.(3)The MIDAS/GTS numerical simulation software was used to calculate and analyze the impact of the fault structure fracture zone on the stability of the tunnel excavation under the three working conditions of dry season,normal rainfall and high rain season.Under certain conditions such as the spatial relationship between the tunnel and the fracture zone of the fault structure,the tunnel excavation method and the supporting conditions,the deformation and deformation characteristics and stress-strain characteristics of the surrounding rock of the tunnel are obtained through numerical simulation calculation,and the displacement of the surrounding rock of the tunnel under three working conditions is obtained.The positional relationship between the critical point where large deformation occurs and the fracture zone of the fault structure.(4)Based on the existing advance reinforcement technology of the tunnel,advance reinforcement grouting is proposed for the characteristics of the tunnel construction instability under the special environment of high water and rainy season in the Shaofang Yakou tunnel.Combined with the characteristics of tunnel construction,three thicknesses of grouting reinforcement ring are proposed.By comparing and analyzing the displacement law and stress analysis of surrounding rock under the three grouting ring thicknesses,the economic benefits and construction environment of the tunnel when the grouting ring thickness is 6m Optimal.(5)Through comparative analysis of the monitoring measurement data of the tunnel surrounding rock displacement under the thickness of the 6m grouting reinforcement ring actually used on the tunnel site,it can be seen that there is a slight difference between the simulated tunnel monitoring measurement and the site construction monitoring measurement data.This is because the site geological conditions are complex,and the factors considered in the simulation of the tunnel are less than the actual ones,but the numerical simulation results can guide the tunnel construction. |
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