Study On Mechanical Properties Of Granite Under Unloading Condition

The excavation of underground engineering rock mass is caused by the radial stress and tangential stress unloading load, under the condition of study and unloading rock mass mechanics behavior has important theoretical significance. Based on the granite as the research object, this paper has carried on the indoor uniaxial compression test and cyclic unloading test, the rock failure process analysis software RFPA is used for uniaxial compression and uniaxial cyclic unloading, conventional triaxial compression under different confining pressure and uninstall numerical simulation, analyzes the strength and deformation of rock specimen, acoustic emission characteristics and failure modes, etc. Paper has obtained the following results:(1) In uniaxial compression test basis, the constant lower limit cyclic loading and unloading and cyclic loading and unloading constant difference uniaxial cyclic loading and unloading test under two different paths, the analysis process of loading and unloading granite strength and deformation characteristics of impact track the variation of the elastic modulus and Poisson’s ratio, and analyzes the effect of acoustic emission Kaiser and Felicity effect.(2) Using rock failure process analysis software RFPA2D, uniaxial compression of rock mass and the constant limit cycle and uninstall numerical simulation analysis, reappear the initiation, development, expansion of rock crack until the whole process of penetration, the failure process of rock mass acoustic emission Kaiser effect.(3) The specimen model was different confining pressure triaxial compression simulation, analyze the relationship between the peak strength, residual strength and confining pressure between failure modes and different confining pressures model.(4) Using rock failure process analysis software simulate the RFPA2D unloading confining pressure, stress, acoustic emission and rock mass failure mode analysis the law of the change with confining pressure, is analyzed and unloading trigger mechanism of instability of rock mass.In this paper, based on one-dimensional and unloading mechanics test, the one-dimensional and add uninstall numerical simulation analysis of rock specimens under confining pressure, recreating the crack initiation, extension and penetration process, as the rock and unloading mechanical properties research provides a new method.