Suppressing rockburst by increasing the tensile strength of rock surface: An experimental study

Abstract

Suitable rockburst support is critical for the prevention of rockburst disasters. In the present study, rockburst process and mechanism are investigated first in detail based on laboratory tests. It is considered that the splitting and buckling are two stages that precede the occurrence of rockburst, and buckling is the necessary prior step and precondition of rockburst. Therefore, in this study, it is proposed to use a layer of material with high tensile strength adhered to the rock surface to increase the tangential tensile strength of the surrounding rock surface and then suppress the buckling, hence achieving the purpose of suppressing the rockburst. In our experiments, cement mortar, acrylate, polyurea and basalt fabric were used to create the surface reinforcement layer. To verify the effectiveness of the proposed support strategy, true-triaxial rockburst tests were carried out, with high-speed cameras and an acoustic emission (AE) system used to monitor the failure process. The results show that increasing the surface tensile strength effectively increases the allowable buckling deformation or yielding range of rock, and the severity of rockburst reduces as the surface tensile strength increases. Characteristics of deformation, rock fragmentations and AE show that with the increase of the surface tensile strength, the internal cracking activity before the final failure is more intense, resulting in more small rock fragments formed, and more energy is consumed and dissipated in the fracturing process (continuous expansion, splitting and buckling) with the energy released in a more gradual manner and hence less kinetic energy is available to cause violent rockburst. Therefore the proposed solution is demonstrated to be an effective ground support scheme to suppress rockburst in rock excavations.