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周文东,崔宴伟,王笑然,等. 基于离散元模拟的受载裂隙岩体地震学声发射响应特征[J]. 煤炭科学技术,2024,52(5):1−9. doi: 10.13199/j.cnki.cst.2023-0208
引用本文: 周文东,崔宴伟,王笑然,等. 基于离散元模拟的受载裂隙岩体地震学声发射响应特征[J]. 煤炭科学技术,2024,52(5):1−9. doi: 10.13199/j.cnki.cst.2023-0208
ZHOU Wendong,CUI Yanwei,WANG Xiaoran,et al. Characteristics of seismic acoustic emission of loaded rock containing pre-existing cracks based on the discrete element simulation[J]. Coal Science and Technology,2024,52(5):1−9. doi: 10.13199/j.cnki.cst.2023-0208
Citation: ZHOU Wendong,CUI Yanwei,WANG Xiaoran,et al. Characteristics of seismic acoustic emission of loaded rock containing pre-existing cracks based on the discrete element simulation[J]. Coal Science and Technology,2024,52(5):1−9. doi: 10.13199/j.cnki.cst.2023-0208

基于离散元模拟的受载裂隙岩体地震学声发射响应特征

Characteristics of seismic acoustic emission of loaded rock containing pre-existing cracks based on the discrete element simulation

  • 摘要: 为深入分析裂隙岩体受载时声发射震源响应机制,结合地震学中的矩张量理论,提出了从颗粒相对运动角度计算声发射特征的细观离散元模拟新方法。以含预制雁行裂纹岩体为研究对象,利用颗粒流(PFC)数值模拟软件再现了其裂纹扩展过程及力学−变形特征,基于新开发的声发射响应模拟方法计算得到了声发射事件空间演化、震级分布及矩张量取向特征。研究结果表明:单轴压缩条件下,预制雁行裂纹岩石应力在峰值后突降,裂纹迅速扩展形成宏观主破裂,声发射事件激增,峰后脆性破坏特征明显。由PFC软件获取的张拉、剪切裂纹个数在时间上呈相似增长趋势,但张拉裂纹数量远多于剪切裂纹。基于地震学计算得到的声发射矩震级主要集中在−6.9, −5.9,其分布的G-R统计关系斜率b为1.81。声发射矩张量空间取向与试样破裂张剪类型相吻合,表现在:在翼裂纹区域内声发射矩张量以横向为主,张拉破坏多于剪切破裂;而在主裂纹区域矩张量形态杂乱,张拉和剪切破坏占比接近。基于声发射矩张量T-k图和矩张量R值理论判定了不同加载阶段微裂纹张剪属性,其与PFC获取的张、剪裂纹占比变化趋势基本吻合,而两者对比结果表明选用−20<R<20作为张剪裂纹分区区间比Feignier等建议的−30, 30更为合理。研究成果为精确分析岩体破裂震源特征及张剪属性判识等提供了有益借鉴。

     

    Abstract: To further elucidate the mechanism of acoustic emission (AE) response when a fractured rock is compressed, a new method for calculating the AE characteristics from the perspective of relative particle motion based on the moment tensor theory in seismology was proposed in discrete element simulation. The crack expansion process and mechanical-deformation characteristics were simulated by the particle flow code (PFC). Based on the new AE response simulation method, the spatial evolution of AE events, magnitude distribution and the orientation of the moment tensor were calculated. The results showed that the stress of the pre-cracked rock under uniaxial compressive conditions drops dramatically after the peak, the cracks expanded rapidly into a macroscopic crack, the acoustic emission events surge, and the brittle damage characteristics after the peak are obvious. The number of tensile and shear cracks obtained from PFC showed a similar growth trend temporally, while the number of tensile cracks was more than that of shear cracks. The acoustic emission magnitudes obtained based on seismology principally concentrated in the range of −6.9, −5.9, and the slope of the G-R statistical relationship (b value) was 1.81. The spatial orientation of the AE moment tensor coincided with the tensile-shear cracks: the moment tensor is mainly transverse in the wing crack region, with more tensile cracks than shear cracks; while in the main crack region, the moment tensor was heterogeneous, and the percentage of tensile and shear cracks is close to each other. The tensile and shear properties of microcracks were determined based on the T-k diagram and R-value theory of moment tensor. The trends of the percentage of tensile and shear cracks were basically consistent with those obtained by PFC, while the comparison revealed that using −20, 20 as the interval of tensile-shear crack was more reasonable than that suggested by Feignier et al. The findings provide beneficial reference for accurate analysis of the characteristics of rock cracking seismic sources and the identification of tensile shear properties.

     

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