Study On Large Deformation Control Technology Of Muzhailing Tunnel In Soft Ground

The soft rock and high stress areas across the deep tunnel often leads to large deformation of soft rock, so the effective control of large deformation is very practical significance.Firstly, the large deformation occurring during the construction of the inclined shafts of Muzhailing tunnel is presented in this paper, and the deformation characteristics of surrounding rock are analysed. And then the feasibility study on the methods to control the large deformation by installing pilot tunnel, pilot heading and advance large-diameter boreholes is carried on according to systematic field tests and a lot of test analysis. Then, the analog computation is carried on with FLAC3D so as to provide theory basis for feasibility of the methods to control the large deformation by installing pilot tunnel, pilot heading and advance large-diameter boreholes. Finally, this paper analyzes large deformation mechanism of Muzhailing tunnel from such aspects as surrounding rock geological conditions, environmental conditions,suport technique, tunnel section shape and excavation method, proposes prediction method and preventive measures of tunnel great deformation.The methods to control the large deformation by installing pilot tunnel, pilot heading and advance large-diameter boreholes are proven feasible according to systematic field tests and numerical analysis. On the one hand further study to perform stress control tests is needed, on the other hand it is also needed to combine stress control tests with other control deformation measures very effectively to realize controllability stress release, and make primary support resistance to the effect of ground stress after the release of the stress so as to achieve the goal to control large deformation.