Generation of and countermeasures against time-delayed rockbursts

Time-delayed rockbursts abruptly release huge energy, characterized by suddenness, randomness, and destructiveness, leading to substantial damage to both lives and property. This study explores the occurrence of time-delayed rockbursts through statistical analysis of case studies in deep tunnels, including an extremely intensive time-delayed rockburst case. Through on-site surveys, blasting vibration tests, numerical calculations, and true triaxial compression experiments, this study analyzes the main factors and prevention and control strategies of time-delayed rockbursts based on an extremely intense time-delayed rockburst case. The results show that most time-delayed rockbursts are of high intensity. Paramount factors influencing their occurrence consider in-situ stresses, structural planes, and dynamic disturbances. Both high in-situ stress and its gradients provide the necessary conditions for such events, while the presence of abundant structural planes and frequent dynamic disturbances largely increase the risk of rockburst potential. To mitigate the risk of time-delayed rockbursts, energy control strategies are essential, incorporating measures such as energy reduction, prerelease, energy transformation, and energy absorption. Additionally, wave-absorbed support technology can reduce the amplitude and frequency of dynamic disturbances, further decreasing the likelihood of a rockburst occurring. Time-delayed rockburst occurrence requires long disturbance durations, compared to immediate rockbursts. Long-term, continuous, and multiple dynamic events will cause significant damage accumulation and formation of microcracks in hard rock. This study offers insights into the mechanisms underpinning time-delayed rockbursts and proposes prevention strategies for their control. • Time-delayed rockburst occurs after stress adjustment and is triggered by external disturbance • Frequent dynamic disturbances usually increase the risk of time-delayed rockburst • Energy control method could be adopted to mitigate the time-delayed rockburst • Wave-absorbed support technology facilitates effectively weak dynamics disturbance