Experimental Research Of Mechanical Properties Of Granite Under Water-Rock Interaction

The special property of the deep surrounding rock under high confining pressure and high pore water pressure conditions has troubled deep coal excavation, also is the chief issues that rock mechanics need to solve. Granite is selected as the research object. The strength and deformation characteristics of granite are studied through laboratory tests simulated water-rock coupling conditions with coal deep excavation. Based on the test results, the deformation and failure process of granite is analysed by the principle of energy, the chief study job are as follows:Through comparison test results of four confining pressure and four pore water pressure, the effect of confining pressure on the strength of granite is much larger than the pore water pressure. The effective peak strength of granite increasing with the effective coupling pressure in the relationship of a quadratic function.The relationship between the effective shear strength and effective normal stress conforms to the Mohr-Coulomb strength criterion.Through the analysis of the relationship between bulk strain and stress of granite under water-rock interaction,the starting point of expansion occurs hysteresis with the enlargement of confining pressure, with the increase of pore water pressure the starting point of expansion comes early.Take strain softening parameters as media to study mechanical parameters of strain softening stage of granite under water-rock interaction.The generalized friction angle keeps unaltered, while generalized cohesion decreases with the increasing of strain softening parameters.After having a preliminary understanding to the mechanical properties of granite under water-rock interaction, the whole deformation and failure process of granite under water -rock interaction is explained in the energy principle.Then the failure criterion based on energy principle is amended for granite under water - rock interaction. Comparing the theoretical calculation values with the test results and the empirical strengh criteria calculation values, the failure criterion based on energy principle after amended is derived to be security for future engineering applications.