Test And Study On Dynamic Mechanical Properties Of Rocks Under High Temperature

The development of deep mining,confining pressure and deep rock mass engineering can not be separated from the influence of the high temperature environment.It is of great importance to study the dynamic mechanical properties of rock under high temperature environment.The analysis results have important reference for the stability and safety of rock engineering in high temperature environment and the blasting effect of related rock mass.The SHPB test system under the high temperature environment is applied to test the mechanical properties of dynamic i MPact compression and tensile tests are carried out under different temperatures and different i MPact loads.The following results are obtained:(1)Dynamic uniaxial compression test of sandstone specimens under 0.3MPa to0.8MPa i MPact pressure at different temperatures It was concluded that the relationship between peak strength,dynamic elastic modulus and peak strain of sandstone specimens varied with temperature under the same loading rate.The i MPact fracture degree of sandstone specimen decreases and then increases with the increase of temperature.It can be seen that the mechanical properties of sandstone under high temperature have changed significantly co MPared with normal temperature,and its dynamic failure characteristics reflect the strength characteristics of sandstone.(2)Based on the thermal damage constitutive model of Weibull distribution,considering the influence of temperature and load,the damage constitutive model suitable for hard rock under kilometer deep is established,which provides a theoretical basis for exploring new method of deep rock burst.(3)Dynamic compression tests at different loading rates were carried out for specimens from normal temperature to 1000?.It is concluded that under different loading rates,the peak strength and loading rate of sandstone specimens increase by two times polynomials.From the failure form,the influence of loading rate on sandstone is not only related to temperature,but also related to its nature.The analysis results have important reference for the stability and safety of rock engineering in high temperature environment and the blasting effect of related rock mass.(4)The dynamic splitting tensile test of sandstone under six i MPact pressure fromnormal temperature to 800? is carried out at six kinds of i MPact pressure.The results show that the dynamic splitting tensile strength of sandstone specimen increases first and then decreases with the increase of temperature at the same loading rate.The relationship between the dynamic tensile strength and the average strain rate of sandstone at different temperatures is similar to the power exponent,and it has a strong dependence.(5)The incident energy,reflection energy and absorption energy of sandstone specimen show a steady trend after increasing a certain value with the increase of time.The reflected energy is far greater than the transmission energy.At the same temperature,the incident energy increases with the increase of the i MPact pressure.At the same i MPact pressure,the incident energy,absorption energy and reflection energy at 800? are higher than the corresponding energy at normal temperature.