Experimental Research on the Effect of Bedding Angle on the Static and Dynamic Behaviors of Burst-Prone Sandstone

Abstract

AbstractIn order to understand the mechanism of some unconventional failures such as rockburst caused by deep rock excavation, the failure characteristics of burst-prone sandstone specimens under static and dynamic loads were studied by using the MTS816 rock mechanics testing system and the split Hopkinson pressure bar (SHPB) experimental system, as well as the effects of bedding angle and impact pressure on rock mechanical properties and failure patterns. The uniaxial compression test used a cylindrical specimen with a height of 50 mm and a diameter of 100 mm, and cylindrical specimens with height and diameter of 50 mm were adopted in the SHPB tests. The bedding angles in the tests are 0°, 45°, and 90°. In the dynamic impact test, three different impact pressures were applied to observe the magnitude of impact load on the mechanical behaviors of the burst-prone sandstone specimens. The results show that with the increase in the bedding angle, the uniaxial compressive strength firstly decreases and then increases. When the bedding angle is 45°, the uniaxial compressive strength is the lowest. The uniaxial compressive strength is highest when the bedding angle is 0°. The burst-prone sandstone specimens with different bedding angles had three different failure pattern types. Under the dynamic loading, the stress-strain curves show springback phenomenon; with the increase in impact pressure, the dynamic strength of the burst-prone sandstone specimens with each bedding angle increases; the fracture degree of the bedding sandstone specimens gradually increases. The dynamic strength of the 45° burst-prone sandstone specimen is the lowest, and it has the highest fracture degree.