Abstract: In order to investigate the bolting effects of prestressed bolt on coal-rock combinations (CR), four sets of uniaxial compression tests were carried out on CR containing prestressed bolt (CRPB) and bolt (CRB) at different interface inclination angles (15°, 30°, 45° and 60°), and the mechanical responses of the CRPB and CRB were analyzed from failure mode, stress-strain curve and acoustic emission (AE) characteristics. The results show that the ratios of residual stress to peak stress for the CRPB are higher. Additionally, the application of prestress increases the energy release before the peak stress, and effectively inhibits the energy release after the peak. Moreover, the prestress also reduces the damage of the contact surface between the combination and the bolt when the sliding failure occurs, and weakens the stress fluctuation. The proportions of low-frequency and high-amplitude (LF-HA) AE signals of the CRPB and the CRB both increase first and then decrease with the application of load. However, the prestress inhibits the concentration of LF-HA AE signals when the slide occurs at interface between coal and rock. Moreover, under different interface inclination angles, the proportion of LF-HA AE signals of the CRPB and the corresponding standard deviation are lower, indicating that the prestressed bolt effectively inhibits the initiation of microcracks before the peak of the combination and reduces the sensitivity of the microcracks evolution to the variation of interface inclination angle.

Key words: coal-rock combination, interface inclination angle, prestressed bolt, acoustic emission characteristics, control mechanism