Influence of Two Cooling Methods on Dynamic Mechanical Properties of High Temperature Sandstone

To study the influence of different cooling methods on dynamic mechanical properties of high temperature rock, both natural cooling and water cooling were used to cool high temperature (100°C∼1000°C) coal mine sandstone to room temperature (20°C). Basic physical parameters of sandstone were measured, and impact compression tests were carried out by using the SHPB test device. Comparative analysis shows that the volume expansion rate, mass loss rate, density reduction rate, and P-wave velocity reduction rate of sandstone specimens are positively correlated with the temperature in a quadratic function. The deteriorate rate of physical parameters of water cooling sandstone specimens is slightly larger than that of natural cooling. The variation of dynamic stress-strain curves is basically consistent. Compaction stage of water cooling is slightly larger than that of natural cooling. With the increase in temperature, dynamic compressive strength of sandstone specimens first increases, then decreases, and reaches maximum at 300°C. Subsequently, dynamic compressive strength decreases in a quadratic function with the temperature, and dynamic compressive strength of water cooling sandstone specimens is significantly lower than that of natural cooling. The dynamic elastic modulus also first increases and then decreases with the temperature and reaches maximum at 300°C. The dynamic elastic modulus of water cooling sandstone specimens is lower than that of natural cooling, but they are roughly the same at 1000°C. Dynamic strain increases in a quadratic function with the temperature, and dynamic strain of water cooling sandstone specimens is greater than that of natural cooling. The impact failure of sandstone specimens is intensified with the temperature, and the failure degree of water cooling is greater than that of natural cooling.