Coal bursts, arising from abrupt dynamic disturbances from mining tremors, are among the most critical dynamic disasters in underground coal mines. Understanding the dynamic disturbance process of mining tremors is crucial for unravelling the mechanism behind coal bursts and identifying high-risk zones. However, previous studies have often utilized oversimplified source representations to model the dynamic disturbances induced by mining tremors. These approaches may overlook complex wavefields resulting from the focal mechanism, leading to distortion in the dynamic disturbance process. In this study, a time-dependent moment tensor obtained from full-waveform inversion was employed as a more accurate source representation of mining tremors to model its dynamic disturbance process. Full-waveform moment tensor inversion was achieved in the time domain by decomposing the source time function (STF) into a weighted sum of several basis functions. To illustrate this methodology, a mining tremor that triggered a coal burst at Huating Coal Mine was selected as a case study. Based on a multi-layered geological model, the time-dependent moment tensor of this event was inverted and interpreted, revealing that the high-magnitude mining tremor spanned a duration of hundreds of milliseconds, rather than occurring instantaneously. Subsequently, a three-dimensional multi-layered FLAC3D model was constructed to reproduce the dynamic disturbance process of the mining tremor based on its moment tensor. The FLAC3D modeling revealed complex wavefields and radiated patterns. Obvious shifts in the peak zone of peak particle velocity (PPV) and principal stress magnitude (PSM) relative to the source position were observed in the coal seam due to the influence of focal mechanism and medium structure. Results from monitoring points within the coal seam show that a dynamic disturbance process characterized by complex cyclic loading and unloading at an intermediate strain rate, accompanied by intricate paths of principal stress rotation (PSR). Numerous monitoring results indicated that the PPV and PSM exhibit a logarithmic linear attenuation pattern as the target-source distance increases, and the dynamic stress magnitude is approximately three times the product of PPV and medium wave impedance. This modelling approach can enhance our understanding of the principal stress variation induced by mining tremors in a complex mining environment with coupled static-dynamic loadings.

中文翻译：

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基于时间相关矩张量的采矿震动诱发动态扰动过程数值研究


煤爆是由采矿震颤引起的突然动态扰动引起的，是地下煤矿中最关键的动态灾害之一。了解采矿震颤的动态扰动过程对于揭示煤爆背后的机制和识别高风险区域至关重要。然而，以前的研究经常使用过于简化的震源表示来模拟采矿震颤引起的动态扰动。这些方法可能会忽略由聚焦机制产生的复杂波场，从而导致动态干扰过程的失真。在本研究中，采用从全波形反演获得的瞬态矩张量作为更准确的采矿震颤源表示，以模拟其动态扰动过程。通过将源时间函数 （STF） 分解为几个基函数的加权和，在时域中实现了全波形矩张量反演。为了说明这种方法，我们选择了一次引发华亭煤矿爆炸的采矿震颤作为案例研究。基于多层地质模型，对该事件的时间相关矩张量进行了反编译和解释，揭示了高震级采矿震动的持续时间为数百毫秒，而不是瞬间发生。随后，构建了三维多层 FLAC3D 模型，基于其矩张量再现了采矿震颤的动态扰动过程。FLAC3D 建模揭示了复杂的波场和辐射模式。 受震源机制和介质结构的影响，煤层中粒子峰值速度 （PPV） 和主应力大小 （PSM） 峰值区相对于源位置发生了明显变化。煤层内监测点的结果表明，动态扰动过程的特点是以中等应变速率进行复杂的循环加载和卸载，并伴有错综复杂的主应力旋转 （PSR） 路径。大量监测结果表明，随着目标-源距离的增加，PPV 和 PSM 呈现对数线性衰减模式，动态应力大小约为 PPV 和中波阻抗乘积的 3 倍。这种建模方法可以增强我们对在具有耦合静态-动态载荷的复杂采矿环境中采矿震动引起的主应力变化的理解。