Research on the tensile mechanical properties of saturated sandstone damaged by deep hole blasting

To explore the splitting tensile mechanical properties and crack propagation laws of water-saturated sandstone damaged by blasting loads under different loading rates, the SHPB device was used to conduct splitting tensile tests on the damaged sandstone at different blast core distances under different loading rates, and combine the high-speed camera device to obtain the crack propagation process of the damaged sandstone. Analyze the influence laws of blast core distance, loading rate and saturated water on the tensile strength, DIF, crack propagation and fracture morphology of sandstone. The results show that (1) There is a linear positive correlation between the peak dynamic tensile strength of the specimen and the loading rate, and there is a strain rate effect in the dynamic tensile strength. Blasting load damage can enhance the sensitivity of the strain rate effect of sandstone materials. (2) There is an exponential positive correlation between the DIF of the damaged specimens at different blast core distances and the loading rate. Due to the existence of the hydrodynamic coupling strengthening effect of water and rock, the increase in DIF of sandstone specimens with saturated water damage is higher than that of natural specimens. (3) Both blasting load damage and saturated weakening damage reduce the deformation capacity of rock mass against external loads, and the damage to rock mass caused by the superposition of the two is more significant. The crack width produced by the specimen under the same impact load is larger and the complexity of crack propagation is higher. (4) The increase in loading rate, the saturation effect and the blasting load all lead to an increase in the crack propagation degree and the wedge-shaped shear fracture area of the specimens. This research can provide a theoretical basis for the pressure relief design of deep hole blasting in a water-rich environment.