Experimental Study On Mechanical Properties And Permeability Of Granite After High Temperature Quenching

In the mining process of dry hot rock,the physical and mechanical properties of the rock are affected by different cooling water temperatures and high-temperature quenching and rapid cooling.Therefore,this paper conducts an experimental study on the physical and mechanical properties of the granite after high-temperature quenching.In addition,in the mining process of hot and dry rocks,the surrounding rock is in the environment of multi-field coupling of temperature,stress and seepage,so the study of the physical and mechanical properties of rocks under multi-field coupling is an important factor to evaluate the safety of underground resources in the long-term mining process.Therefore,the physical and mechanical properties of single fracture granites treated by high temperature quenching were studied in this paper.To solve the above problems,this paper carried out experimental research on the basic physical properties of granite after high temperature quenching,and on this basis,carried out permeability test on granite containing single crack after uniaxial compression and shear tests respectively,and analyzed the influence law of temperature and confining pressure on permeability.In this paper,different temperatures(200 ° C,400 ° C,600 ° C,800 ° C)were used to heat the granite,and different cooling water temperatures(0 ° C,25 ° C,80 ° C)were selected to quench the granite after heating.Based on this carried out after the high temperature quenching granite uniaxial compression test and shear test,and respectively to the uniaxial compression and shearing test with single fractured granite conducted under the condition of different confining pressure permeability test,analyzed the basic physical properties of granite after high temperature quenching treatment,study the physical properties of high temperature heat treatment after granite along with the evolution law of heat treatment temperature;The evolution of compressive strength,shear strength and permeability of granites with heat treatment temperature is also discussed.The main conclusions are as follows:(1)The dry density and saturated density of granite show a trend of gradual decrease with the increase of heat treatment temperature,while the porosity and permeability show a trend of increasing,with 400? as the critical value,and differentwater temperature treatment has little impact on the physical properties of granite.The thermal conductivity and sound wave of granite gradually decrease with the increase of heat treatment temperature.Through the specific surface area test,it is found that a large number of micro cracks occur in the granite after high temperature quenching treatment,which makes the specific surface area and pore volume increase.(2)In the cooling process of different water temperatures,the cooling rate gradually increases with the increase of heat treatment temperature,while the cooling time gradually lengthens with the increase of heat treatment temperature.Different water temperatures have little influence on the cooling rate.(3))After quenched at high temperature,the elastic modulus and peak strength of granite are similar with the increase of heat treatment temperature: the compressive strength,shear strength and elastic modulus of granite decrease with the increase of heat treatment temperature,and the degree of deformation increases with the increase of heat treatment.The internal friction Angle of granite increases with the increase of heat treatment temperature,while the cohesive force decreases with the increase of heat treatment temperature.The shear strength increases with the increase of confining pressure,and the failure form of rock changes from brittleness to ductility with the increase of heat treatment temperature.(4)The relationship between the permeability coefficient obtained through uniaxial compression seepage and shear seepage and hydrostatic pressure and temperature is consistent: the permeability coefficient decreases gradually with the increase of hydrostatic pressure,and decreases gradually with the increase of heat treatment temperature.