Effects of thermal shock due to rapid cooling on the mechanical properties of sandstone

Underground engineering can lead to high-temperature disasters in which the rocks surrounding underground structures are heated because of the presence of a high-temperature source. The surrounding rock will experience rapid cooling with the subsequent disaster relief efforts. Thus, it is important to elucidate the effects of rapid thermal cooling (RTC) on the physical and mechanical properties of rocks for real-world engineering applications. In this study, the effects of RTC treatments on the physical and mechanical properties of sandstone were examined at temperatures ranging from 100 to 800 °C through uniaxial compression tests, wave velocity tests, acoustic emission tests, and scanning electron microscopy. The results show that the decrement ratios for both the P-wave velocity and the density of sandstone increased with increases in temperature, and the decrement ratio for the density lagged behind that of the P-wave velocity. The uniaxial compressive strength and elastic modulus values for the sandstone samples varied similarly with increases in temperature following RTC treatments. The variations were divided into three stages: a stable stage, a slow falling stage, and a quick falling stage. Moreover, under uniaxial compressions, no changes in the ductility of the sandstone samples were observed following the RTC treatments, and the specimens were brittle in nature during the postpeak stage.