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<p>Time-delayed rockbursts are a new type of rockburst, triggered by multi dynamic disturbances, like blasting-induced vibration, TBM, earthquake, and among others. These external long-term dynamic disturbances generate after the stress has readjusted itself around a cavity after it has been excavated. Dynamic disturbances cause the damage to progressively accumulate in the surrounding rock which means that the bearing capacity of the rock continuously decreases. Thus, a time-delayed rockburst can subsequently ensue if the bearing capacity of the rock can no longer withstand the post-excavation stress present. As their occurrence cannot be accurately predicted (both in time and location), time-delayed rockbursts pose a huge risk to the safety of the construction personnel and equipment. In this work, a total of 793 time-delayed rockburst cases were recorded at field. The primary characteristics of the time-delayed rockbursts were summarized, including delay time, intensity, excavation disturbance experienced, initial support applied, etc. Most time-delayed rockbursts appear within 30&#xa0;days of excavation, and their distance from the working face lies in the range 30–60&#xa0;m. However, in some cases, the rockburst was found to occur hundreds of meters away, or years after excavation. The support applied near the rockburst crater was found to be generally rather weak, so the rockburst events primarily occurred in moderately and weakly supported sections. Time-delayed rockbursts occurred much more frequently when drilling and blasting methodology was operated, rather than TBM. The effects of geostress, structural planes, and dynamic disturbances have on time-delayed rockbursts were further investigated by analyzing an intense time-delayed rockburst. High-stress fields (such as those in valleys) can provide the energy to drive the rockburst. Structural planes cause energy accumulation and control the boundary of the rockburst. External dynamic disturbances (such as earthquakes and blasting) lead to additional fractures forming in the rock mass and damage accumulation, and this plays a crucial role in triggering the generation of a time-delayed rockburst. Time-delayed rockbursts are also more likely to occur at the interface of different support systems as the stress environment there changes significantly due to the different <i>σ</i><sub>3</sub> components present. Two other time-delayed rockburst cases were explored and a detailed description of their spatio-temporal and dynamic disturbance characteristics presented. The information derived from the three cases considered was finally utilized to comprehensively examine the development process involved in the time-delayed rockbursts. It involves a period of stress concentration, initial energy release, and a further energy release after the dynamic disturbance is experienced.</p>

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Time-Delayed Rockbursts Induced by Dynamic Disturbances: 793 Cases in Deep Tunnels

  • 期刊论文

  • 发表日期：

    2025年4月15日

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  • Ben-Guo He,
  • Heng-Yuan Zhang,
  • Xia-Ting Feng,
  • Xiang-Rui Meng

摘要

Time-delayed rockbursts are a new type of rockburst, triggered by multi dynamic disturbances, like blasting-induced vibration, TBM, earthquake, and among others. These external long-term dynamic disturbances generate after the stress has readjusted itself around a cavity after it has been excavated. Dynamic disturbances cause the damage to progressively accumulate in the surrounding rock which means that the bearing capacity of the rock continuously decreases. Thus, a time-delayed rockburst can subsequently ensue if the bearing capacity of the rock can no longer withstand the post-excavation stress present. As their occurrence cannot be accurately predicted (both in time and location), time-delayed rockbursts pose a huge risk to the safety of the construction personnel and equipment. In this work, a total of 793 time-delayed rockburst cases were recorded at field. The primary characteristics of the time-delayed rockbursts were summarized, including delay time, intensity, excavation disturbance experienced, initial support applied, etc. Most time-delayed rockbursts appear within 30 days of excavation, and their distance from the working face lies in the range 30–60 m. However, in some cases, the rockburst was found to occur hundreds of meters away, or years after excavation. The support applied near the rockburst crater was found to be generally rather weak, so the rockburst events primarily occurred in moderately and weakly supported sections. Time-delayed rockbursts occurred much more frequently when drilling and blasting methodology was operated, rather than TBM. The effects of geostress, structural planes, and dynamic disturbances have on time-delayed rockbursts were further investigated by analyzing an intense time-delayed rockburst. High-stress fields (such as those in valleys) can provide the energy to drive the rockburst. Structural planes cause energy accumulation and control the boundary of the rockburst. External dynamic disturbances (such as earthquakes and blasting) lead to additional fractures forming in the rock mass and damage accumulation, and this plays a crucial role in triggering the generation of a time-delayed rockburst. Time-delayed rockbursts are also more likely to occur at the interface of different support systems as the stress environment there changes significantly due to the different σ3 components present. Two other time-delayed rockburst cases were explored and a detailed description of their spatio-temporal and dynamic disturbance characteristics presented. The information derived from the three cases considered was finally utilized to comprehensively examine the development process involved in the time-delayed rockbursts. It involves a period of stress concentration, initial energy release, and a further energy release after the dynamic disturbance is experienced.