Experimental study on dynamic mechanical properties of post-high-temperature sandstone

The sandstone samples were heated at the rising temperature rate of 10°C/min from 25°C to 100, 200, 400, 600, 800 and 1000°C, respectively, by using a RX3-20-12 box-type resistance furnace. They were being kept at the corresponding temperatures for 3 h. Then the heated sandstone samples were naturally cooled to 25°C. All the sandstone samples were divided into seven groups according to the temperatures undergone by them. By using a thin red copper circular plate as the pulse shaper, the sandstone samples were impacted by the different-velocity projectiles driven by a 100-mm-diameter split Hopkinson pressure bar setup. And the stress-strain curves of the sandstone samples subjected to impact were obtained as well as their failure modes. Experimental results show that the stress-strain curves of the sandstone samples at constant temperature obviously take on four stages, but the platform stages disappear in the stress-strain curves of the sandstone samples undergoing 100-400°C and they appear again when the temperatures undergone by the sandstone samples continue to rise. As the temperatures undergone by the sandstone samples rise, their peak strains and stresses increase; but when the temperatures undergone exceed 800°C, the peak stresses fall suddenly. The impact load and the heat temperature can affect the failure mode of sandstone, the break degree increases with the increasing of the impact load and the damage develops from the outer of sandstone to the core.