Experimental Investigation on Pressure Relief Mechanism of Specimens with Prefabricated Reaming Boreholes

Rockburst has always been a worldwide tricky problem in the mining industry, and reaming borehole pressure relief technology has technological superiority in preventing and controlling rockbursts. To investigate the influence of different borehole parameters on the mechanical properties, crack evolution and energy change laws of specimens, confined compression experiments were performed on specimens with different borehole diameters, reaming lengths and spacing. First, the theoretical analysis of the reaming borehole pressure relief mechanism is conducted, illustrating the effect of borehole parameters determining the stress distribution characteristics around the borehole. Then, the effect of the borehole parameters on the mechanical behavior is analyzed in detail. The test results indicated that the larger the diameter, the reaming length and the smaller the borehole spacing, the lower the peak strength and elastic modulus. Furthermore, the relationship between failure behaviour and borehole diameters is analyzed based on the AE behavior and fracture characteristics. Finally, the analysis of internal energy evolution further confirmed that increasing the borehole diameter, reaming length, and reducing the borehole spacing can increase the dissipation strain energy to achieve a better pressure relief effect. Highlights A new reaming borehole pressure relief technology is proposed, which could reduce the damage to the shallow anchored surrounding rock while achieving effective pressure relief of the deep surrounding rock. The prefabricated borehole specimens are tested to study the influence of borehole parameters on mechanical behavior. The energy evolution characteristics of specimens with prefabricated reaming boreholes are analyzed to better understand the pressure relief mechanism.