The Classification And Stability Evaluation Of The Surrounding Rock Of Chongqing Tongrong High-speed Zeng Jiashan Tunnel

Since the reform and opening up,the state has paid more and more attention to infrastructure investment and construction,especially in the construction of railways and highways.Along with the development of science and technology and the improvement of the construction method,the development trend of the road tunnel is more and more profound and the development trend is irreversible.This paper takes Chongqing Tong Rong Expressway had Jiashan tunnel project as the basis,using qualitative and quantitative methods of surrounding rock classification and evaluate the stability of tunnel import and export,using COMSOL Multiphysics software to simulate the tunnel after excavation,the surrounding rock stress and displacement of the change,the main research results are as follows:(1)Using the BQ method for surrounding rock classification,Zeng jiashan line around the tunnel surrounding rock is divided into Ⅲ,Ⅳ,Ⅴ three levels.Right line: Ⅲ level of surrounding rock of the largest,length of 687 m,accounted for42.22%;Ⅳ class surrounding rock length of 475 m,accounted for 29.19%;Ⅴ level of surrounding rock of the youngest,a length of 465 m,accounted for 28.58%.Left line: Ⅲ level of surrounding rock of the largest,length of 690 m,accounted for42.38%;Ⅳ class surrounding rock length of 480 m,accounted for about accounted for 29.48%;Ⅴ level of surrounding rock of the youngest,a length of 458 m,accounted for about 28.13%.(2)According to the classification of surrounding rock of highway tunnel design specification evaluation indicators and jiashan the geological conditions of the tunnel using six assessment factors,set up evaluation index system,using the theory of fuzzy mathematics,the tunnel surrounding rock classification,the classification results are consistent with the BQ method.(3)By the method of plane projection diagram section tunnel import and export of stability evaluation: the natural state import and export section of the slope stability is good,but a category Ⅴ,of surrounding rock mass is broken,the bucklingdeformation may occur frequently in the tunnel construction,and need to support in a timely manner.(4)Tunnel five typical sections using COMSOL Multiphysics software to carry on the numerical simulation,analysis of the tunnel after excavation,the surrounding rock stress and displacement distribution characteristics and change law: Ⅲ level section of surrounding rock,the stability of surrounding rock is good,small displacement;Ⅳ level section of surrounding rock,the stability of surrounding rock,large displacement and was positively related with buried depth;Ⅴ level section of surrounding rock,the stability of surrounding rock is poorer,large displacement.