Research On Optimizing Tunnel Construction Schemes And Parameters In Water-bearing Fractured Zones

During the construction of a tunnel in Xinjiang,the tunnel site passes through three large-scale fault-breaking zones along Fl,F2 and F3 along the tunnel site.The faults are high-pressure and water-rich and the rock mass is crushing and joints are developed.Water gushing,collapse and other engineering problems easily occur in the construction,which seriously affect the safety of tunnel construction..The paper relied on the tunnel project,combined with geological survey data and site design and construction conditions,using literature research,theoretical analysis,numerical simulation and on-site monitoring data analysis methods to compare the construction methods of the tunnel crossing the F1,F2 water-rich fault zone.And parameter optimization to ensure the safe construction of the tunnel.The main research content of the paper is:1.Research on advance pre-reinforcement scheme of tunnel faceAdvanced pre-grouting:By means of theoretical analysis and numerical simulation,the feasibility of grouting method of " up-plugging,down-draining and down-draining" for water plugging and reinforcement of water-rich and weak broken surrounding rock in front of the tunnel face is studied,and grouting parameters are designed,including the radial grouting range and longitudinal grouting length of the tunnel.Arch pre-support:In the case of pre-grouting construction parameters determined,through theoretical analysis,numerical simulation and other means to advance small pipe support,t76 self-drilling high strength pipe roof support two kinds of support methods were compared,choose the best pre-support scheme,to ensure the safe construction of the tunnel.2.Comparison of tunnel excavation schemes and optimization of parametersOn the basis of advance support scheme and parameter determination,two excavation methods of Ring excavation reserved core soil method and Two-step method are compared,and then parameter optimization is carried out to improve the construction efficiency on the premise of ensuring the construction safety..3.Research on advance support method of pipe shed without workshop in inclined shaftLong pipe shed pre-support is adopted for tunnel main hole.this support method needs to be used as pipe shed working room.expanding and digging pipe shed working room in fault fracture zone increases construction risk and excavation workload,thusprolonging construction period and increasing construction cost therefore,no working room 12m middle pipe shed pre-support method is adopted for tunnel research based on No.1 inclined shaft to safely pass through water-rich fault fracture zone..The dissertation mainly relies on the difficulties encountered by the tunnel engineering in faults,and the research results have been applied in the field with good results and can provide reference for similar projects in the future.