Classification Of Surrounding Rock Of Tunnel And Stability Analysis Of Surrounding Rock Based On Multi-factor Extension Element Method

At present,China’s transportation construction facilities are constantly developing and expanding,especially in the construction of tunnels,light rails and high-speed railways.In general,the construction of highway tunnels presents the following conditions:more and more roads are being built,more and more difficult,longer and deeper.Therefore,the design and construction of highway tunnels should be more refined.In order to better solve the problems encountered in the construction of highway tunnels,it is particularly important to analyze the level of surrounding rock and the stability of surrounding rock.Based on the Xishanying Tunnel Project in Yunnan Province,this paper uses the surrounding rock quality classification correction[BQ]method to classify the surrounding rock,and combines the improved analytic hierarchy process and the extenics evaluation theory to classify the surrounding rock of the tunnel,then comparing the two methods,it is concluded that the theory method of the modified[BQ]method to carry on the classification of surrounding rock is reasonable.The stability of the entrance and exit tunnel slope was evaluated by using the Chiping polar projection method.Using the finite difference method FLAC3D to several kinds of surrounding rock under different excavation are numerically simulated and analyzed when excavation changes,the tunnel vault displacement,collapse will happen,then the tunnel surrounding rock under different excavation supporting numerical simulation and analysis way of excavation and supporting effect on the stability of surrounding rock.The main research results are as follows:（1）According to the improved BQ method of surrounding rock classification results are compared with extension matter-element surrounding rock classification results in addition to 16,21,24,29,31 classification results,the rest of the surrounding rock classification result is the same,but 16,21,24,29,31 segments with extension classification results of the proceeds of the grade of surrounding rock were IV₂、IV₁、IV₁、IV₁、IV₃BQ method of the surrounding rock grade respectively V₁、V₂、V₂、V₁、V_2,BQ method to the income level of surrounding rock are of extension matter-element income level transformation of surrounding rock.By comparing the two methods of surrounding rock classification,the results of the two methods are the same,which verifies the accuracy and rationality of the extension matter-element.（2）According to the graphic projection of the entrance and exit slope of xishanying tunnel,according to the cross-sectional analysis of the entrance and exit section slope,the rock strata trend is beneficial to the stability of the slope,joints and fissures are developed,which has a certain impact on the excavation of the slope.The tunnel should be supported before construction.（3）It is concluded that when the excavation distance of a full section is 2 meters,it is4 meters more stable than that of a full section,and it is more suitable for the excavation of surrounding rock in this project.In the case of abundant groundwater,the tunnel should be timely protected during construction excavation.