Experimental Study On Mechanical Properties And Acoustic Emission Law Of Heat-treatment Granite Rock Under Triaxial Unloading Confining Pressure

Heat-treatment rock mass is an kind of special and complicated rock mass that encountered frequently in the human engineering activities from shallow to deep. The strength, deformation and failure characteristics of post-high temperature rock under excavation unloading condition will directly influence the safty of the human engineering. In order to study the mechanics and failure characteristics of heat-treatment rock mass under unloading, this paper uses granite as the research object. the main work are as follows:(1) Conduct the tests of quality, volume, density, porosity and sound waves for the post-high temperature(25~900℃) granite samples. The test results show that: with the temperature rises, the quality and density of rock decreased, the volume and porosity rate decreased first and then increased, the wave velocity and main frequency value increased first and then decreased.(2) The loading and unloading experiments of the heat-treatment rocks were performed. Contrast the stress and strain characteristics, strength characteristics and failure pattern under different kind of stress paths. And focus on the analysis of deformation features and deformation parameters of thermal-damage rock under unloading condition. The results show that: Granite rocks undergoing heat-treatment of 300℃ are easiest happened to damage.(3) The real-time AE monitoring for heat-treatment rocks were performed when going on mechanical compression tests under different stress paths by AE signal acquisition system. AE signal can reflect the damage evolution situation of the internal structure of rock. Therefore, the AE signal characteristics for different post-high temperature rocks under the uniaxial compression, general triaxial compression and unloading confining pressure were studied by means of AE technology. Synthetically analysis the deformation and failure rules of heat-treatment rock Combining with macro mechanical properties.(4) Based on test data, study the laws of energy dissipation of heat-treatmentrock under the uniaxial, triaxial compression and unloading. Discuss preliminarily the influence bettwen temperature, stress path and energy dissipation law. And defined the damage variable from the point of energy dissipation, then analysised preliminarily the evolution law of damage in the internal structure of rock.