Experimental Study On Dynamic Behavior Of Thermal Treated Granite

With the development of the economy of our country,the application of rock mechanics is more and more extensive in mining,civil engineering,water conservancy and transportation.At the same time,rock mechanics is also facing challenges.In recent years,with some national major projects carried out,such as deep resource extraction,geothermal energy development and disposal of high-level radioactive nuclear waste in deep formations,there are more and more problems related to physical and mechanical properties of rock after high temperature.Scholars concerned more on the dynamic behavior of rock mass under Multi-Physical-Field coupled excitations.The physical and mechanical properties of rock after high temperature treatment are related to the safety evaluation and reconstruction of rock engineering.In this paper,investigation has been done from four aspects:1.Wave velocity and density of granite were measured by ultrasonic experiment on samples after single heat and repeated heat treatment.The variations of elastic modulus and damage variable were analyzed by changing heat temperature and number of heat times;2.Micro cracks were observed by SEM tests on samples after single heat treatment.And the relation between microstructure and mechanical properties was revealed;3.SHPB tests were carried out to investigate dynamic mechanical properties of granite after single and repeated heat treatment.The failure characteristics of samples were analyzed,and the variations of peak stress and energy absorption were analyzed by changing heat temperature and number of heat times;4.A physical image synchronization analysis system composed of the SHPB and a high speed camera was set up.The results directly reflect the relationship between mechanical properties and the corresponding images information in different stages of the stress-strain curve under impact load.It also demonstrates the mechanical mechanism of deformation and fracture of the rock.In this paper,the macroscopic and microcosmic mechanical experimental methods were used to study the dynamic behavior of thermal treated granite.The research provides a reference for safety evaluation of rock engineering after high temperature.