NUMERICAL ANALYSIS OF REASONABLE SUPPORT TIMING FOR SECONDARY LINING OF HIGH STRESS SOFT ROCK TUNNEL
Taking a tunnel on the Lanzhou to Chongqing railway as the research object,considering the creep characteristics of carbonaceous shale formations,conduct three-dimensional numerical simulation of the tunnel construction process by using the generalized Nishihara model.Studied the deformation law of initial support and secondary lining under different support timing.The results show that:(1)Pre construction of secondary lining can form a superimposed support system with initial support,effectively restraining soft rock deformation and reducing deformation rate.The earlier the construction time,the better the control effect of surrounding rock deformation.(2)The timing of stress support for initial support and secondary lining is related.The earlier the construction time of the secondary lining,the better the stress state of the initial support,reduce the initial support stress,and share the greater deformation pressure of the surrounding rock,resulting in greater secondary lining stress.
soft rock tunnelhigh geostresssecondary liningviscoelastic plasticitynumerical analysis
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