Study On Marble Mechanics And Fracture Seepage Characteristics

With the continuous development of rock mass engineering to the deep,the geological and stress environment is forced to become more complex and diverse.To master the mechanical properties of rock under the conditions of high in-situ stress and high permeability pressure is the basis for ensuring long-term stability of underground structures.In view of this,two problems occurred in the excavation of the deep-buried diversion tunnel of Jinping II Hydropower Station are the rock burst disaster of surrounding rock under high in-situ stress and the inrush disaster under high water pressure.The laboratory tests of marble mechanics and fracture seepage characteristics are carried out,and the basic mechanical properties of marble are obtained and the seepage characteristics of the structure plane are summarized.The numerical model of marble is established based on voronoi polygon,and the mechanical properties of marble are shown reasonably.The numerical model of the marble is established based on the Voronoi polygon,and the mechanical properties of the marble are reasonably represented.The main contents of this paper are as follows:(1)The wave velocity of the standard cylindrical specimen of marble was measured and the uniaxial compression test and direct shear test were carried out in the laboratory.The conventional uniaxial compressive strength and shear strength of marble are obtained.The whole process curve of stress and strain in uniaxial compression process of marble is drawn.By observing and summarizing the macro-fracture process of marble,the failure characteristics of marble specimen are grasped.(2)The point cloud data of the shear crack surface of cylindrical specimen is obtained by means of three-dimensional scanning equipment,and then the point cloud data is extracted by Geomagic Studio software.The data of fracture surface point cloud are further processed by Matlab software,and the shape parameters of shear fracture surface are quantitatively analyzed and calculated.(3)An experimental device for radial seepage is developed.Different normal loads are placed on the end of the cylindrical fracture surface.By controlling the infiltration flow,the relationship among the seepage flow,infiltration water pressure and normal stress is obtained and discussed,and the relationship between the seepage flow,the infiltration water pressure and the normal stress is discussed.In this paper,the seepage characteristics of marble shear fractures are studied from the view of the shape of shear fracture surface to seepage process.(4)The direct shear test under complex stress path is carried out.The effect and mechanism of the complex stress path on the strength of the rock samples were discussed by comparing with the results of the conventional shear test,and the destruction process and the destruction characteristics of the marble samples under different stress paths were compared and analyzed.(5)Based on the Voronoi convex polygon,the numerical model of the cylindrical and square samples of the marble is established.Based on the discrete element method,the process of deformation and failure of the rock under the conventional uniaxial compression and complex stress path is simulated,and the development process of the fracture is summarized.The process of deformation and failure of marble in different stress paths is discussed with the indoor test.