Study On Mechanical Properties Of Granite Under High Temperature And High Pressure

Dry hot rock resources are renewable and clean energy,and the potential for exploitation is huge.Therefore,the efficient use of dry hot rock resources has an important meaning to energy structure transformation in China.The dry hot rock resources are in the real-time high-temperature and high-pressure interaction environment.The bottleneck of limiting the efficient utilization of dry heat sources lies in the lack of research on the mechanical properties of rocks under real-time high temperature and high pressure.Therefore,real-time high-temperature triaxial tests are carried out for real-time high-temperature and high-pressure environments.The in-depth study of rock mechanical properties under the action is of great significance to China’s energy structure adjustment and sustainable development.The real-time high-temperature true triaxial test system was independently developed to give real-time high-temperature and high-pressure environment to granite.The real-time high-temperature triaxial test of granite was carried out,it’s physical and mechanical properties and microstructure were analyzed and studied.The main work are as follows:(1)A 50×50×100mm granite sample was prepared and its density,thermal conductivity and mineral composition were measured.(2)Using a real-time high-temperature true t:riaxial test system,samples at steady temperature of RT、100、200、300 and 400℃,uniaxial test and confining pressure of 20,40 and 60 MPa conventional triaxial experiment were carried out.The full stress-strain curve,sample failure morphology,mechanical properties and crack propagation of granite under real-time high temperature and tbree-dimensional stress environments are studied and analyzed.(3)The true triaxial tests of the third principal stress(40MPa)and different intermediate principal stresses(40、50 and 60 MPa)at RT and 400°Cwere carried out,and the effects of temperature and intermediate principal stress on the mechanical properties of granite were studied.(4)Through the SEM micro-structural analysis of the samples after real-time high-temperature triaxial test,the failure law of the internal structure and the micro-destruction characteristics of the failure surface of the granite specimen were investigated.By comparing the mechanical properties and microscopic characteristics of the granite under different experimental conditions,the formation mechanism of microfractures in granite was analyzed.