Study On Surrounding Rock Stability Of Large-span Compressed Tunnel Through Fault And Fracture Zone

With the rapid economic development in the world,no matter from the nationalproduction to people’s life,the demand for transportation capacity is rising,in such a backdrophighway tunnel get rapid development. With the cumulative increase of engineeringexperience, as well as construction technology improvement, the tunnel engineering witch isunable or difficult to achieve even before can now become a reality, and also have a lot ofnew technology and new project. The stability of surrounding rock and constructionmechanics behavior of Large-span flat tunnel crossing the fault fracture zone is studied anddiscussed. Based on the reality of Luwan tunnel, mainly for the following research work:(1) Large-span tunnel and tunnel with fault fracture zone has been built or being built athome and abroad are summarized. In view of the common fault fracture zone in the process oftunnel construction is a typical bad geological condition, from the formation mechanism toform and management measures are analyzed. The stability of surrounding rock under theinfluence of various controlling factors, such as geological environment, own attribute,groundwater function, initial stress, construction load and concrete construction methods, etc.(2) Through the analysis and combined with tunnel engineering actual situation, thetreatment method of leading conduit grouting technology aiming at the fault fracture zone isdetermined. Using ANSYS software, the same geological conditions of Luwan tunnelexcavation simulation is researched and general mechanics characteristic of the tunnelexcavation, including ground stress field is analyzed. Including stress field, displacement,internal force of retaining structure, vault subsidence and peripheral convergence, etc., as thecoMparison basis of large-span flat tunnel crossing the fault fracture zone with advancesupport or not.(3) Through ANSYS software simulated the large-span flat tunnel crossing the faultfracture zone is applying and not applying advanced support, concluded that the existence ofthe fault fracture zone of surrounding rock stability influence is very obvious, it adds to thestress and deformation of surrounding rock, which had the greatest influence on vault,because it promotes the vaults of the stress relaxation phenomenon and the development oftensile stress, thus easy to deform the vault severe further lead to instability. Because of the existence of the fault fracture zone makes the supporting structure of the arch position forcebecome larger, increasing the difficulty of supporting at the same time, but when the tunnelwas made advance ductule, since the stability of surrounding rock ability get promoted,suppress the deformation of the arch, increases the stability of surrounding rock, visibleadvance ductule reinforcement of fault fracture belt tunnel excavation effect is obvious.