| Much has been done to study the theory and test methods of rocks.But due to the limitations of actual conditions on site,the field test is difficult to carry out and it is difficult to analyze each specific problem in theory.Together with the progress of society and the development of science and technology,the rock The research methods are not limited to theoretical analysis and experimental testing.Numerical simulations begin to play an important role in the rock research process,and numerical simulation is a more effective means to explore the microscopic fracture and damage of rocks.Therefore,the study of numerical simulation methods of rock can not only make up for the deficiency of theory and experiment,but also better explain the mechanism of rock internal rupture.It is of great significance for the study of rock engineering mechanical properties.This paper relies on the National Natural Science Foundation of China,“Deep-buried hard rock dominant structure and unloading rupture synergistic time-varying mechanism research?Y611021A01?”,the rock fracture behavior of intact marble direct shear test and deep hard rock excavation process was studied by establishing a new Bonded Block Model?BBM?.Based on the random block generation technique?Neper?and the block discrete element theory?3DEC?,a new bonded block model method?BBM?is established;by studying the influence law between the mesoscopic parameters and the macroscopic parameters of the plane strain BBM model and the three-dimensional BBM model,the influence law of the mesoscopic parameters on the macroscopic parameters in the BBM model method is obtained.The BBM method was applied to the simulation of the intact marble direct shear test and the simulation of the 7#hole and 8#hole excavation process in the underground laboratory of Jinping.It is discussed that the rock failure mechanism during the process of direct shear testing of intact marble and deep hard rock excavation.The main research results are as follows:?1?Based on the random block generation technique?Neper?and the block discrete element theory?3DEC?,the following six models are established:plane strain single-axis BBM model,plane strain Brazilian split BBM model,plane strain triaxial BBM model,three-dimensional single Axis BBM model,3D Brazilian split BBM model and 3D triaxial BBM model.?2?It is obtained that the law of the impact of five mesoscopic parameters?BBM model contact normal stiffness?kn?,contact normal-tangential stiffness ratio?kn/ks?,contact tensile strength?J?T?,contact cohesion?Jc?and contact internal friction angle?J???on eight macro parameters(BBM model uniaxial compressive strength??p?,Brazilian splitting tensile strength??T?,elastic modulus?E?,Poisson's ratio?v?,cracking stress(?CI)and damage stress(?CD),model viscosity Cohesion?c?,internal friction angle???.of the model.?3?Through the direct shear test of intact marble,the shear failure characteristics and shear stress-shear displacement curves of intact marble under the five normal stresses of 1MPa,2MPa,5MPa,10MPa and 15MPa are obtained.The following four stages of shear failure of intact marble are described:initial shear stage,shear damage stage,shear stage,and secondary shear shear.?4?The BBM method was applied to the simulation of the intact marble direct shear test,and the shear failure characteristics and shear stress-shear displacement curves of the BBM model under the five normal stresses of 1MPa,2MPa,5MPa,10 MPa and 15MPa were obtained.The four stages of shear failure of the BBM model are described:the initial shear stage,the shear damage stage,the shear stage,and the secondary shear shear,which explains the fracture mechanism of the intact marble direct shear test.?5?The BBM method was applied to the simulation of the excavation process of the 7#hole and 8#hole in the underground laboratory of Jinping.The behavioral characteristics of deep hard rock under the action of high ground stress were obtained,and the deformation ability of the surrounding rock of the tunnel was described.Also it is explained the fracture mechanism of surrounding rock in deep hard rock under high ground stress. |
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