Numerical Simulation On The Mechinical Characteristic Of Rock Mass Structure Plane And Its Reinforcement Effect By Rock Bolt

Geological material is different from other materials, for it contains many different size interfaces, which are named structure plane like fault, joint, weakness plane and stratified plane etc. They break the continuous of the rock mass, and control the geological characteristic of rock mass. So it is meaningful to study the mechanical characterisitic of rock mass structure plane, and its mechanical effect induced by the different loading.The mechanical and deformation characterisitic of structure plane, the response of structure plane with bolt reinforcement, joint rock slope stability and joint rock slope with bolt reinforcement are studied in the present thesis, according to the method of theoretical analysis, insitu-test and the numerical calculation method. The results of the present thesis can give some guidance for the real project.The existed model for describing the relationship between shear stress and shear displacement of structure plane can only reflect the type of plastic structure plane, so this model is modified in the present thesis, which can then describe the stress deformation characteristic of both the plastic and brittle stucture plane.The bolt element in FLAC3D can only reflect the effect of axial stress and axial friction stress, but in reality, the bolt also sustains the shear stress in the normal direction. So it is important to consider the shear stress in the normal direction of bolt, especially for structure plane reinforced by bolt. The bolt element in FLAC3D is modiefied by the internal FISH language, to make it more close to the real situation.According to the insitu-test of bolt with tensile stress, the relationship between the bolt head displacement and the tensile stress are analyzed. Then the bolt tensile test is modelled by the numerical calculation method, in which the modified bolt element is used. The comparisons are done for the results obtained from the insitu-test and the numerical analysis method, which validates the correctness of the modified bolt element done in the present thesis. The data transferring program from ANSYS to FLAC3D is compiled, in which the data transferring method is different from those in other papers, the data transferring method can greatly increase the data transffering effeciency, and the complicated suface for structure plane can be modelled by this program.The shear strength, stress-strain relationship and the failure mode of structure plane are analyzed. The theoretical models are founded for them. The method useing interface to model the structure plane is analyzed, the relationship between the normal displacement and shear displacement is studied, which shows the shear dilatant characteristic of structure plane, and the shear dilatant theoretical model is founded. The effect of the shear velocity to the shear strength of structure plane is studied, and there fitting model is built.The relationsip between the shear strength and the joint thickness is analyzed, the fitting equations are founded for them with different roughness angles.The characteristic of stress and deformation of structure plane with bolt reinforcement are seldom studied in the existing material. But in the present thesis, this problem is studied by the numerical simulation method, in which the modified bolt element is used. The strength characteristic and stress-strain characteristic are compared for the situations of structure plane with the without bolt reinforcement of different inclination.In order to do the optimal study for the joint rock slope with bolt reinforcement, the effect of bolt parameters like bolt length, bolt inclination and bolt spacing to the stability of joint slope are studied, whose results can give some guidance for the real project.