Coal mine pillar burst frequently occurs in Western China, which seriously restricts safe production. This paper takes the 35 m coal pillar of the 3102 working face of MKQ coal mine as the engineering background. The mechanism and evolution control of pillar bursts in multithick key strata are studied using field investigation, theoretical analysis, and numerical simulation. The mechanism of dynamic and static stress-induced pillar bursts was revealed combining the “O-X” broken features for key strata and numerical simulation of pillar stress evolution. A prevention scheme is put forward for strata presplit blasting and adjusting coal pillar width to minimize the dynamic and static stresses. The results demonstrate the following. (1) In the multithick strata, the first and second near-field subkey strata have perpendicular “O-X” broken features, whereas the third far-field subkey has parallel “O-X” broken features. The working face has three kinds of periodic weighting phenomena: long, medium, and short. (2) The simulated vertical stress curve of 35 m coal pillar goes through three states: two-peak, asymmetric trapezoidal and symmetrical trapezoidal shape with the different advancing position of working face. The stress concentration is extensively promoting a high-risk area for rock burst. (3) The coal pillar burst was induced by the superposition of energy released by the key strata breaking and the elastic energy accumulated in the wide coal pillar. (4) The monitoring data showed that the long, medium, and short periodic weighting steps of multithick key strata are 141.6 m, 43.2–49.6 m, and 17.6–27.2 m, respectively. The microseismic events energy, frequency, and stress of hydraulic support increment are the highest during the long periodic weighting, and the spatial distribution of microseismic events coincides with the stress concentration area. The theoretical analysis is confirmed with the field practice.

中文翻译：

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多厚关键层宽煤柱爆裂机理及演化控制

西部地区煤矿支柱爆裂事故频发，严重制约了安全生产。本文以MKQ煤矿3102工作面35m煤柱为工程背景。运用野外调查、理论分析和数值模拟等方法，研究了多层关键地层中柱爆的机理和演化控制。结合关键地层的“OX”破碎特征和柱应力演化的数值模拟，揭示了动静应力引起柱爆的机制。提出了地层预裂爆破和调整煤柱宽度使动静应力最小化的预防方案。结果证明如下。(1) 在多厚地层中，第一和第二近场子关键地层具有垂直的“OX”破碎特征，而第三个远场子密钥具有平行的“OX”损坏特征。工作面有长、中、短三种周期性加重现象。(2) 35 m煤柱模拟竖向应力曲线随着工作面推进位置的不同，经历了双峰、不对称梯形和对称梯形三种状态。应力集中正在广泛地促进岩爆的高风险区域。(3)煤柱爆裂是由关键地层破裂释放的能量与宽煤柱中积累的弹性能量叠加引起的。(4) 监测数据显示，多厚关键层长、中、短周期加权步长分别为141.6 m、43.2～4​​9.6 m、17.6～27.2 m。微震事件的能量、频率、水力支架增量的应力和应力在长周期加权过程中最高，微震事件的空间分布与应力集中区相吻合。理论分析得到了现场实践的证实。