Study On The Bearing Capacity Of The Supporting Member In The Tunnel Shotcreting And Bolting Support System

In recent years,with the continuous development of highway traffic in China,the new-built tunnel is becoming more and more mature.The new highway tunnel usually adopts the new Austrian tunneling method,in which the shotcrete bolt support is used as the bearing unit and the secondary lining as the safety reserve unit.From the view of safety,it is necessary to find out the stress characteristics of each supporting member.From the cost point of view,it is also necessary to understand its characteristics to optimize its supporting parameters.Therefore,in this paper the problems which are about the failure characteristics of shotcrete-bolt support,the effectiveness and the bearing capacity of each supporting member have been studied.Based on the model test and numerical simulation,the problems which are about the failure characteristics of shotcrete-bolt support,the effectiveness and the bearing capacity of each supporting member are systematically studied.The research is as follow:(1)According to the research content of this paper,the model test scheme is designed.The similar material of surrounding rock,bolt and shotcrete is developed,and the test equipment and measurement system is completed.It makes the similarity model test go well.(2)Under the condition of IV and V grade rock,the model test which has eight conditions monitored the displacement deformation characteristics under different loading forces,and compared the ultimate bearing capacity of rock bolt and shotcrete.It obtains the bearing capacity of each supporting member.(3)This paper uses the finite difference software FLAC3D.Combine with the elastic-plastic stress characteristics of the surrounding rock,the inter-laminar shear stress transfer characteristics of the full-column binding rock bolt and the deformation coordinate relationship of the contact interface between shotcrete and surrounding rock,the paper gives a in-depth study in the effectiveness and the bearing capacity.(4)Based on the model test and numerical analysis,it obtains the effectiveness and the bearing capacity of each supporting member.It makes the conclusions of the two research methods be verified each other.The conclusions can provide a basis and guidance for the design and construction of the new two lane highway tunnel in the future.