Mechanical properties of sandstones after high temperature under dynamic loading

The mechanical properties of sandstone specimens such as density, longitudinal wave velocity, peak dynamic strength are studied under dynamic compression loading after being heated at different temperatures (25℃～800℃). Dynamic fragmentation characteristics of sandstone specimens are analyzed from different aspects of failure mode, fragment distribution and high-speed photography. The testing device of SHPB is adopted to conduct the dynamic experiments of rock specimens experiencing high temperatures. Though the experimental results are discrete, the general law is obvious. The results show that, with the increasing temperature, the specimen density, the longitudinal wave velocity and the peak strength all gradually decrease, and the decreased magnitude of the longitudinal wave velocity increases when the temperature is over 200℃. And the temperature changes from 400℃ to 600℃，the peak strength of rock has less decreased magnitude, and decreases sharply when the temperature is over 800℃. The dynamic failure characteristics of sandstone are mainly tensile failure after high temperature, with the increasing temperature, when rock fragmentation degrees increase, rock blocks become smaller. Through high-speed photography, dynamic failure process of rock is expressed. It is obtained that radial cracks are distributed around the specimens along the loading direction, the failure mode of rock is not representative at the initial loading, but the final failure mode of rock is obtained through the stress wave multiple reflection.