| According to the characteristics of the tunnel entrance is shallow and the upper cladding layer is difficult to form bearing arch during tunnel construction, based on the basic principle of NATM and finite element, using two kinds of means of field monitoring tests and ANSYS three-dimensional simulation method, the status of entrance stability are evaluated and researched of one mountain tunnel in Zhejiang province, China. the rock deformation and stress variation are researched and the effective parameters for design and construction are provided by combining with two methods' results, Specific research work and relating results are as follows:(1)The interaction of tunnel surrounding rocks and support are studied on the basis of NATM theory, and the tunnel portal slope failure mode is also researched.(2) Compare with obtained data which from in-site monitoring and test on the actual project and the related stability index, the stability of the tunnel is judged.Structure deformation and stress characteristics of slope and tunnel supporting structure in the process of tunnel construction are researched, and the project sensitive area affected by the excavation and abnormal area in engineering by the analysis. Some reasonable building suggestions are also put forward.(3) Using the ANSYS finite element software, non-synchronized excavation in the practical engineering are simulated, and the field monitoring results are compared with to verify the reliability of the results. Comprehensive analysis of tunnel surrounding rock deformation and stress variation regular pattern are worked out.(4) Through the comparative analysis, the results of the simulation which changed the strength parameters of the tunnel entrance surrounding rock and tunnel support, the effect of relative displacement and stress variation are studied, and the safety factor of tunnel surrounding rock stability is calculated to provide the theory basis for the tunnel design and construction. |
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