Numerical investigation of seismic wavefield characteristics induced by a tensile source in a heterogeneous mining environment
Numerical investigation of seismic wavefield characteristics induced by a tensile source in a heterogeneous mining environment
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DOI：
10.1016/j.ijrmms.2023.105549
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发表时间：
2023-10
影响因子：
7.2
通讯作者：
Fan Chen;Zhengzhao Liang;Anye Cao
中科院分区：
文献类型：
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作者：
Fan Chen;Zhengzhao Liang;Anye Cao
采动震动是煤矿突出动应力的主要来源，是煤矿井下最严重的采矿灾害之一。评价煤矿突出风险、了解煤岩体对地震波的响应，微震监测是主要方法。通过根据地震事件群推断煤爆风险较高的区域，可以获得有价值的见解。然而，由于单个地震事件产生的地震监测结果有限，对相应动态扰动过程的识别仍然不明确。由于震源机制和非均质介质，特别是在大规模采矿作业引起的结构异质性影响下，动态扰动过程呈现出巨大的复杂性。在本研究中，采用正演数值模拟来了解提取区对地震波传播的影响。研究结果揭示了工作面周围波场的复杂性和位移集中度的增加。分别研究了近场和远场区域的峰值粒子速度（PPV）和位移谱的特征。由于提取区的存在，在近场区周围观察到显着的放大效应和PPV的重新分布。由震源机制和提取区引起的复杂波场导致低频频谱水平的分布更加分散，这可能会导致源强度的高估。然而，复杂波场对角频率的影响有限。通过分析PPV衰减规律以及地震矩和震源半径的分布，本研究为地震风险评估提供了有价值的见解。正演建模方法有助于识别地震事件引起的高风险潜在区域，加深了我们对复杂地下矿山环境中动态扰动过程的理解。
Mining-induced tremors serve as the main dynamic stress source of coal bursts which represent one type of the most critical mining disasters in underground coal mines. To evaluate coal burst risks and comprehend the response of the coal-rock mass to seismic waves, microseismic monitoring stands as the principal method. By inferring the zones with elevated coal burst risks based on the seismic event clusters, valuable insights can be gained. However, because of limited seismic monitoring results generated from an individual seismic event, the recognition of the corresponding dynamic disturbance process remains ambiguous. The dynamic disturbance process presents immense complexity due to the focal mechanism and heterogeneous medium, particularly under the effect of structural heterogeneity induced by large-scale mining operations. In this study, forward numerical modelling was employed to gain the comprehension of seismic wave propagation affected by extraction zones. The findings revealed heightened intricacy of the wavefields and increased displacement concentrations around the working face. The characteristics of peak particle velocity (PPV) and displacement spectra were investigated in the near- and far-field zones, respectively. Owing to the existence of the extraction zone, both a significant amplification effect and the redistribution of PPV were observed around the near-field zone. The intricate wavefield caused by the focal mechanism and extraction zones resulted in more scattered distributions of the low-frequency spectral level, which can potentially cause an overestimation of source intensity. However, the impact of the complex wavefield on the corner frequency was limited. Through the analysis of the PPV attenuation law, as well as the distribution of both seismic moment and source radius, this study offered valuable insights for seismic risk assessment. The forward modelling approach facilitated the identification of high-risk potential areas resulting from seismic events, which deepened our comprehension of the dynamic disturbance process in the complex underground mine environment.