Experimental Study on Rockburst of Sandstone with Different Bedding Dip Angles

To investigate the influence of the law and mechanism of different bedding inclinations on impact rockburst, this study conducted a series of impact rockburst experiments on sandstone specimens with five kinds of bedding angles (0 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees) using self-developed true-triaxial impact rockburst equipment. A microcamera device and an acoustic emission (AE) monitoring system were used to monitor and record the experiment process in real time. The results demonstrate that with the increase in bedding angle, the peak stress of the sandstone specimen rockburst showed a trend of decreasing and then increasing, the AE counts and cumulative energy showed a trend of decreasing and then increasing, and all of them reached the minimum values at 60 degrees. In addition, from the perspective of energy and crack evolution, this study preliminarily reveals the mechanism of bedding angle on impact rockburst, which include: (1) as cracks continue to develop, the bedding surfaces can influence the crack development and expansion patterns, allowing them to expand through along the bedding surfaces, thus providing a channel for energy release. (2) As the bedding surface is a weak surface, blocks formed by crack development are more susceptible to slip and separation along these bedding surfaces, thus, the elastic energy accumulated before the rockburst is reduced, resulting in a decrease in the intensity of the rockburst. The results of this study have theoretical and practical significance for an in-depth understanding of the mechanism of rockburst and help guide the prevention and control of rockburst disaster in underground engineering. A series of impact rockburst experiments were conducted on sandstone specimens with five bedding angles (0 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees) using self-developed true-triaxial impact rockburst equipment.The effects of different bedding angles on impact rockburst were investigated from four aspects: stress characteristics, acoustic emission characteristics, fragment characteristics, and rockburst notch geometry.From the perspective of energy as well as crack evolution, the mechanism of the impact rockburst by bedding angle is preliminarily revealed.