Buried Surrounding Rock Deformation Characteristics And Control Methods

In view of the new problems of surrounding rock support in deep coal mining, taking the Wangfenggang and Zhuji Coal Mine in Huainan Mining Area for examples, the regional geological tectonic features are analysed and the general rules of tectonic stress field are aquired.The mechanical indexes of mud rock and sand rock in Wangfenggang Coal Mine are obtained by one dimensional and triaxial mechanical properties tests, such as the strength, poission ratio, cohesion, internal firction angle and so on. Triaxial unloading shear tests and creep tests are done to get the original creep threshold of stress and creep failure critical stress of the layered interface rock mass.The deformation and rupture of deep tunnel surrounding rock are measured by borehole digital panoramic imaging techniques and installing convergency meter, multipoint extensometer, anchor shank tension meter, ultrasonic detecting instrument in roadway surface.According to the displacement difference analysis of geostress effect on different strtum, the computational formulas of ruptre breadth are deduced by elastopastic theory with the consideration of rock mass expansion.As to the supporting structure, the expressions of bonding length and the bearing capacity of bolted rock mass are derived.It's found that the primary rupture zone is induced by construction techniques and the others are aroused by the displacement difference effect of layered surrounding rock under geostress.The mechanisms as well as the conditions of floor heave are discussed, and the calculation formulas of floor heave depth are suggested.The influences of rock mass compound mode on the surrounding rock deformation of deep tunnel are analyzed so as to probe the feasibility of semirigid lattice steel frame and steel bar mesh bolted shotcrete support.Then the support parameters of central water pumping room passage in-960m level are designed for Wangfenggang Coal Mine second auxilary shaft.Finally,the numerical simulation for the supporting structure is performed by using FLAC-3D software.And it turned out that the support pattern accords with the actual needs of the in-situ project very well.