Study On The Stability Of Surrounding Rock And Applying In Engineering Of Shallow Tunnel Under Unsymmetrical Pressure

Through long-term underground structure construction practicing,researchers found that tunnel could have the capacity of self-stability when was in a certain range of surrounding rock around,what is called the theories of self-stabilized hidden arch.Practices showed that when under a certain condition the tunnel surrounding rock can be stable without any supporting structures.In modern days,highway tunnel engineering is under complicated variable situations,and the classification level of surrounding rock of a single span is large,the stability of surrounding rock can't be grasped accurately,leading to the truth that the design scheme of tunnels is conservative.As a result,more research about the stability of surrounding rock need to be done,and more scientific tunnel construction plan need to be designed.Considering the research about stability of surrounding rock at native and abroad,this paper's analyses direction would pay more attention in the field of which deep influencing in the modern engineering projects,which the factors are the shallow and the unsymmetrical pressure.The research was relying on the Yu-xiang tunnel and using numerical simulation method to simulate the stability of the tunnel after excavation hole with focusing on the two indicators of influence about the shallow and the unsymmetrical pressure,by the results,the classification of surrounding rock stability was managed.And with the classification of stability,the method of numerical simulation was been using to optimize the primary supporting scheme according to different classes.With the results above,the resources could be saved and the cost of project could be depressed.The research results show that the two indicators can divide the stability of the tunnel into three levels,with which the tunnel primary support scheme was optimized,among them,the optimization scheme that the amounts of material and the parameters,such as the thickness of the wet shotcrete optimization which is about 20 cm?50 cm thick,bolt is about 2 m?5 m and the steel arch turn 22 beams into 18 beams.The actual monitoring data is closed to the data of optimization scheme,therefore,the optimization scheme is feasible.On the premise of safety construction,the optimization of the primary supporting obtain certain managements.The results can provide reference for the design and construction of the tunnel in the similar geological conditions.