Mechanism and simulation experiment of slip-type rock bursts triggered by impact disturbances

The slip-type rock burst caused by the sliding of structural surfaces is sensitive to external disturbances and may release huge energy. Once it occurs, it may have catastrophic consequences for construction workers and engineering equipments. Using the self-developed test device and the high-speed photography technology, the whole process of the slip-type rock bursts from initial sliding to slip instability under impact disturbance is simulated. The mechanism is discussed from three aspects including external causes, internal causes and incentives. After an external impact, the propagation of stress waves in the blocky rock masses can lead to the reduction of friction, which is known as the ultra-low friction phenomenon. Once the friction force of structural planes reduces to a value less than the initial shear force of the structural plane, the rock block begins to slip. If the final dynamic friction force is still less than the shear force, the rock block will continue to slip, causing the blocky rock masses to be instable and collapse, namely a slip-type rock burst. The sliding motion between rock blocks induced by impact disturbance is closely related to the initial stress level of structural surfaces. A dimensionless energy parameter is introduced to characterize the critical energy condition of slip-type rock bursts induced by dynamic disturbances, and the quantitative relationship between the energy parameter and the initial stress state of the structural plane is given. It is concluded that three conditions need to be met for the occurrence of slip-type rock bursts: there are weak structural planes (internal causes) in the block rock mass, the stress conditions on the structural planes are close to the critical state (external causes), and the dynamic disturbance causes the shear strength of the structural plane to decrease (incentives).