The Research Of Excavation Simulation And Supporting Optimization Design Of Chenxieling Tunnel

With the rapid development of intercity traffic,the number and mileage of tunnels have increased year by year.Among them,rock tunnels are the main ones.The safety and economy of tunnels are the two core indexes of design.However,at present,the traditional design method is difficult to balance the safety and economy for the rock tunnel,generally speaking,the tunnel safety factor is bigger than this of the standard and the construction cost is higher,the optimum design is not achieved.This paper takes Chenxieling Tunnel as an analysis case,the tunnel is the section of the G318 Fulan Line Zixi Huashanjie to the Nancheng Huangshidu,by actual monitoring and data analysis,finite element numerical simulation,support optimization design based on orthogonal experiment,and engineering application.With the effect analysis,a series of optimization studies of tunnel support are carried out from the safety and economy aspect,which provides reference for the design and construction of similar rock tunnels.the main contents and conclusions are as follows:(1)An overview of the chenxieling tunnel.The design of the tunnel clearance section is used to lay the foundation for the contour of the tunnel in the numerical simulation.The the supporting structure the use of ordinary cement mortar anchors and C25 strength grade shotcrete.Staying the same as a constant factor in support optimization.(2)The surrounding rock displacement is obtained by field measurement and will be compare with the numerical simulation results,and then analyze the data in the regression analysis.by comparison,the exponential function as the optimal fitting function,the final deformation of the surrounding rock is 19.95 mm.The best construction time for secondary lining is the 15 th day after tunnel excavation.(3)Comparing analysis by numerical simulation and actual measurement of the vault settlement displacement the upper and down guide clearance displacement,the data is basically consistent,and the correctness of the model is verified.At the same time,obtained the stress variation regular of the surrounding rock,obtained the internal force and stress variation regular of the supporting structure.(4)Using the thickness of the spray layer,the number of anchor,the length of the anchor,the diameter of the anchor and the longitudinal spacing of the anchor as the optimization parameters,established the safety index formula of the surrounding rock and improved the economic index formula of the anchor spray support.by the comprehensive index to obtain the best support optimization plan by the results of range and variance analysis.The optimal solution is: shotcrete C25 thickness 10 cm,anchor number(single section)11,anchor length 2.5m,anchor diameter 22 mm,anchor longitudinal spacing 0.6m,optimization scheme for engineering application,the result is safe reliable and economical.Providereference and help for the design and construction of the same type of rock tunnel.