Study On Surrounding Rock Stability Of Tunnel By Double-shield TBM Excavion

Compared with the traditional of tunnel excavation method,the double nursing shield TBM method construction on tunnel surrounding rock of disturbance is small and can effectively maintain the stability of surrounding rock of capacity,therefore in tunnel design and construction stage can be effective use of the stability of surrounding rock strength,reduce the design parameters of supporting structure,save engineering material,also can ensure the construction of security,and high quality.However,the main problem of using TBM to excavate tunnels is whether the stability of the surrounding rock can ensure the normal drivage of TBM,avoiding the accidents such as the card machine and the buried machine.Existing methods of classification of surrounding rock are mostly in view of the new Austrian method,drilling and blasting method to judge the tunnel surrounding rock mass,but those in view of the double shield TBM excavation of tunnel surrounding rock quality evaluation methods of study are less and immature.Due to adopt double shield TBM construction method of tunnel surrounding rock by mechanical and segment isolation,construction personnel can not intuitive to get geological conditions of surrounding rock,so the traditional method of classification of surrounding rock in the construction of double shield TBM method is not applicable.This paper on the basis of the existing surrounding rock classification,selected double shield TBM tunneling parameters and the design parameters as indicators of tunnel surrounding rock classification,based on entropy-right method theory calculation that get six indicators weights about TBM thrust,tool through into degrees,TBM torque,tablets-like rock ballast content,block rock ballast content,powder rock ballast content respectively for 0.106,0.273,0.074,0.060,0.358,and 0.129,set up to***classification method of surrounding rock of tunnel engineering,in order to determine the knife dish in front of the rock mass and verify the actual excavation of tunnel surrounding rock level,obtained the result that of surrounding rock classification by theoretical calculation of entropy-right method is same as rock with actual project.So based on the theory of entropy-right method to tunnel surrounding rock classification,in the process of machine excavation of rock mass,can quickly and accurately understand the excavation of rock mass quality,and according to the quality of rock mass level to guide the tunnel construction,adjust the installation segment model.***tunnel is a deep buried tunnel.The biggest problem of the double shield TBM is big deformation of surrounding rock.If the tunnel surrounding rock deformation is bigger,that will squeeze the shields of machine,block machine,eventually led to the card machine.It is better to study of tunnel surrounding rock deformation,combine the basic value of tunnel surrounding rock deformation control to judge the stability of surrounding rock,complete the advance support measures,in order to ensure the double shield TBM tunneling through smoothly.Therefore,this paper using the FLAC3D software to simulate the deformation of the surrounding rock of jamming accident,get the overall characteristics of the tunnel convergence,deformation of the tunnel working face of the space effect on the surrounding rock significantly.When the double shield TBM continuous driving,it will face forward,and the tunnel surrounding rock tunnel face deformation near the initial change.The deformation is much larger than the surrounding rock.Simulation results show that under the condition of support,the maximum subsidence of the surrounding rock can reach 134.87mm,which is much larger than the amount of excavation and makes the rock mechanical shield around the hole to block the advancing of the roadheader.Therefore,it is of great significance to study the deformation law of surrounding rock to guide the construction of double shield.