Rock Damage and Energy Balance of Strainbursts Induced by Low Frequency Seismic Disturbance at High Static Stress

Seismic disturbances frequently trigger or induce violent strainbursts, threatening regular operations and personnel safety in deep underground excavation. We reproduce the cyclic disturbance-induced strainburst, i.e., the strainburst under combined high static stress and cyclic disturbance conditions in the laboratory using a true triaxial testing system with a relatively low stiffness, where the seismic disturbance is simulated by a low-frequency cyclic load. A damage evolution model that enhances the residual strain method is established to quantify the effects of various factors on the damage evolution of this type of strainburst. The energy budget over the development of the cyclic disturbance-induced strainburst is studied, and its energy criterion and magnitude of the kinetic energy release are also discussed. The damage evolution curve of the cyclic disturbance-induced strainburst is typically inverted S-shaped that is well represented by the inverse logistic function with three stages, i.e., initial stage, constant speed stage, and acceleration stage. It is found that the cyclic disturbance can significantly activate and accelerate rock damage, thus inducing a strainburst. The unique underlying reason is that most of the energy input by the cyclic disturbance is dissipated, which degrades the energy storage capacity and strength of the rock. This energy-based failure mechanism is collectively explained as the ‘rock degradation through energy dissipation’ due to the cyclic disturbance.