State Key Laboratory of Intelligent Construction and Healthy Operation & Maintenance of Deep Underground Engineering, China University of Miningand Technology
School of Mechanics and Civil Engineering, China University of Mining and Technology
State Key Laboratory of Coal Exploration and Intelligent Mining, China University of Mining and Technology
Schoolof Mines, China University of Mining and Technology
Jiangsu Engineering Laboratory of Mine Earthquake Monitoring and Pre-vention, China University of Mining and Technology

为探明脆性煤体受静载作用下细观裂纹演化规律及宏观冲击显现特征,通过实验和模拟相结合的方法开展了煤样受压脆性破断的声发射信号演化及应力降过程研究。结果表明,煤体瞬时应力降过程裂纹演化规律与常规准静态受载过程在裂纹扩展诱发机制和裂纹扩展模式及范围方面均有显著差异:瞬时应力降中局部裂纹剪切滑移引发的大能量震动事件诱发其临自由面细观拉伸裂纹快速扩展贯通,进而形成碎屑并弹射飞出,其过程以拉伸裂纹动态扩展为主,而剪切裂纹在形成贯通面过程中产生;煤体受载大能量震动事件呈局部积聚并向周边扩展的规律,其形成的扰动诱发煤体局部细观裂纹快速扩展贯通及结构动态失稳,引发煤体宏观应力降及冲击显现现象;另外,震动事件、应力降及冲击显现存在时序性。煤体冲击显现烈度与应力降前后刚度比及释放能量正相关,所测试煤样临界刚度比约为 18.2,小于此值时无明显冲击显现现象,反之,随着刚度比和释放能量增大相继呈现少量碎屑弹射、大量碎屑弹射、碎块弹射和剧烈煤爆 4 种冲击显现现象;冲击显现中碎屑弹射速度及动能随刚度比增大有一定的上升趋势,同时碎屑极限速度也相应增大。静载作用下煤体动态失稳过程的研究及结论对理解煤矿冲击矿压孕育演化过程及致灾机理有一定的借鉴作用。

In this study, the acoustic emission evolution and stress drop processes of brittle coal specimens under quasistatic compression were investigated by experiments and numerical simulations, to reveal the pattern of mesoscopic crackevolution and its effect on the macroscopic coal burst characteristics. The results indicate that the crack evolution law during an instantaneous stress drop is dramatically different from that under quasi-static compression, in terms of both the inducement mechanism and the pattern and scope of crack propagation. Upon an instantaneous stress drop, mesoscopictensile cracks around the free face rapidly propagate and coalesce. Subsequently, massive debris are formed and ejected,due to slippage-triggered high-energy seismicity events. During the process, tensile cracks are dominant while shear cracksare mainly generated during crack coalescence. In addition, high-energy seismicity events are localized and then extendperipherally, where the dynamic disturbance leads to rapid evolution of local mesoscopic cracks and structural instability.As a result, stress drop and coal burst take place at the macroscopic scale. Generally, temporality among seismicity, stressdrop and coal burst was found. Moreover, coal burst intensity is correlated with the stiffness ratio and released energy of astress drop event. The critical stiffness ratio is 18.2 for coal specimens in this study, below which no coal burst occurs.With the increase of stiffness ratio and energy release, four types of coal burst behavior, i.e. slight debris ejection, massivedebris ejection, block ejection, and coal bump, successively take place. The mean ejection velocity and kinetic energy ofdebris, as well as the maximum debris ejection velocity, generally increase with the rise of stiffness ratio. Conclusions andfindings in this paper are beneficial to the understanding of coal burst mechanism under quasi-static compression.

国家自然科学基金资助项目(52104101,52227901);中国博士后科学基金资助项目(2022M713369)

鞠明和,朱涵,窦林名,等. 局部震动诱发煤体非稳态裂纹扩展及其冲击显现特征[J]. 煤炭学报,2023,48(5):2035−2048.

JU Minghe,ZHU Han,DOU Linming,et al. Local seismicity induced unstable crack propagation in a coal andits effect on coal burst characteristics[J]. Journal of China Coal Society,2023,48(5):2035−2048.