YiAn Tunnel Surrounding Rockmass Failure Mechanism And Supporting Optimization

Our country is vast in territory and the terrain is complex. The hilly and mountainousareas have a wide distribution, covering about two-thirds of China’s land area. Because ofthe geographic features, tunnel has become an important component of road traffic indifferent stages. The highway tunnel construction has entered into a flourishing age withthe strategy of developing the West and the improvement and scope of highway. Inaddition, building underground traffic has become a revival in the country with the rapidurbanization. With the increase in tunnel engineering, the accidents in the process ofbuilding gradually increase.The paper is set in JianOu YiAn tunnel, analyze instability failure mechanism ofsurrounding rock, evaluate stability of surrounding rock, and optimize the supportingdesign of surrounding rock. YiAn tunnel is located in Fu Jian province, south of JianOuShiCity, far from NaYa town about3km, which is a hilly area through east-west mountainsand stops in the town of NaYa YiAn village. YiAn tunnel import pile is ZK18+970andthe export pile number is ZK21+075, and the tunnel is2105m long,12.42m wide9.0mhigh, which is a long tunnel. Through field investigation, laboratory experiments, fielddrilling methods, I made a detailed analysis and evaluation of highway tunnel engineeringgeological conditions of surrounding rock.I summarize the characteristics of surrounding rock and the process of analysis andobtain the deformation and failure mechanism of surrounding rock. Through the analysisof factors affecting the stability of surrounding rock, I evaluate engineering geologicalconditions of tunnel surrounding rock. Respectively from the perspective of qualitative andquantitative classification, I grade the tunnel surrounding rock. Through study theanchorage mechanism of surrounding rock, I design the tunnel anchorage. Finally I use theFLAC3D numerical simulation software to optimize the design of tunnel anchorage. Before and after the support displacement are compared in tunnel support FLAC3Dnumerical simulation to result in efficient effect. If we take effective support measures, wecan ensure the integrity of the tunnel, the displacement and deformation of continuity. Andwe analyze the axial force of anchor bolt. When the bolt is reach a certain length, axialforce tends to a constant value. Through comprehensive analysis and comparison ofdifferent length and the diameter of the bolt on the displacement of surrounding rock andthe influence of bolt axial force, we can optimize the bolt length and diameter, thus savingcost to reduce the project cost.