Stability Analysis Of Surrounding Rock-Supports Structure Of Fractured Weak Zone In Highway Tunnel

The stability analysis of supporting structure of tunnel surrounding rock is an extremely important study of the safe construction of tunnel. During each stage of the highway tunnel construction, monitoring and analyzing of the displacement of surrounding rock and support body, forecasting of the risky areas of surrounding rock and timely and accurate evaluation of the stability of supporting structure are indispensable prerequisite of reasonable choice of tunnel excavation, support programs and rapid construction. Therefore, it has theoretical and realistic significance for accurately determining the stability of supporting structure of the weak and broken areas.Based on the application of convergence confinement principle in judging of the stability of tunnel displacement, the paper present the concept of ultimate displacement of the tunnel initial support and get the ultimate displacement of the tunnel initial support using the methods of numerical calculation and site monitoring measurement, finally, judge the stability analysis of supporting structure of tunnel surrounding rock of Zhongxing Tunnel. Major work and results achieved are as follows:1)The spatial effect is very obvious during the construction of fractured weak zone. There is a clear deformation in just 20m far from the front working face of the tunnel. What's more, displacement of part of the measuring points could not be measured due to lagging laid. Therefore, it has a certain gap between true value u and measured value um of surrounding rock deformation. If it is at the three measuring points laid far from the working face, u≈1.6 um.2)Based on the analysis of numerical simulation results and monitoring data of Zhongxing Tunnel, the paper indicates that the top and spring of arch are the risk regions during the construction of fractured weak zone and displacement criterion of the stability analysis of supporting structure of tunnel surrounding rock is presented.3)Based on the analysis of numerical simulation results and monitoring data of Zhongxing Tunnel, the paper indicates that pre-design reserved deformation (10cm) of fractured weak zone is not enough, it should be adjusted to a more reasonable value (20cm).