Study on the Dynamic Splitting Mechanical Properties of Annular Sandstone Specimens with Temperature–Water Coupling in a Coal Mine

With the gradual deepening of mine excavation depth, the strong disturbance of deep strata becomes more and more obvious. Rock’s failure under blasting mainly depends on its dynamic tensile strength. The changes in rock’s dynamic properties are obviously affected by temperature and water. In order to study the dynamic tensile properties of annular sandstone specimens under the influence of temperature and water, deep sandstone was drilled, followed by water bath tests at eight temperatures (25~95 °C). It can be seen from the analysis of test results that the mass and volume growth rates of the annular and the intact sandstone specimens first increased and then decreased, while the density growth rate first decreased and then increased. The mass and volume growth rates of the annular sandstone specimens were smaller, but the density growth rate was larger. Because of the increase in water temperature, the dynamic compressive strength first increased and then decreased. The dynamic tensile strength of the annular sandstone specimen was lower. The average strain rate and peak strain also showed a quadratic function relationship of first decreasing and then increasing with the increase in water temperature. The average strain rate of the annular sandstone specimen was smaller, but the peak value changed greatly. The Brazilian disc validity condition is applicable to two failure conditions of sandstone specimens. Through XRD and SEM analysis, we found that the changes in the dynamic properties of sandstone specimens were not due to their own material composition, but to the damage to their structure caused by the temperature–water coupling effect.