State Key Laboratory of Intelligent Coal Mining and Strata Control
CCTEG Coal Mining Research Institute
School of Energy and Mining Engineering, China University of Mining and Technology(Beijing)

为揭示孔隙对煤样力学性质及变形破坏特征的影响,采用UDEC-Trigon开展了不同孔隙率煤样单轴压缩数值模拟试验,分析了不同孔隙率煤样的力学性质和变形破坏特征,研究了孔隙对其宏观变形破坏、微裂隙及声发射演化的影响,阐明了孔隙尖端拉应力集中驱动尖端裂隙产生扩展并贯通导致煤样力学性质及变形破坏变化的影响机制,探讨了孔隙特征对其宏微观力学表现的影响。研究结果表明:(1)随孔隙率的增大,煤样UCS和残余强度呈指数规律递减,弹性模量和变形模量逐渐减小,但泊松比逐渐增大;(2)孔隙影响下煤样内部微观张拉裂隙更易起裂、扩展,随孔隙率的增大,煤样失稳由拉剪脆性破坏向张拉延性破坏转变;(3)孔隙影响下煤样声发射信号由突然急剧增加向缓慢增加演化转变;(4)孔隙尖端拉应力驱动微观张拉裂隙产生并扩展延伸,孔隙率越高拉应力分布范围越广、量值越大,微观裂隙大量起裂扩展并更易贯通,宏观裂纹分布范围越广、数量越多;(5)煤样内部拉应力分布及演化受孔隙结构特征影响显著,影响孔隙尖端微裂隙产生、扩展及贯通,导致煤样力学性质和变形破坏特征产生明显变化。研究成果可为煤矿巷道钻孔卸压防治冲击地压提供参考。

To elucidate the impact of porosity on the mechanical properties and deformation failure characteristics of coal samples, numerical simulations of uniaxial compression on coal samples of varied porosities were con-ducted using UDEC-Trigon. The mechanical properties and deformation failure characteristics of coal samples with different porosities were investigated, exploring the impact of porosity on macroscopic deformation failure, microscopic crack development and acoustic emission evolution.The results show that increasing porosity result in an exponential decrease in the uniaxial compressive strength (UCS) and residual strength of coal samples. The elastic modulus and deformation modulus gradually decreased, while Poisson's ratio showed a gradual in-crease. Under the influence of porosity, internal microscopic tensile cracks in coal samples were more prone to initiation, expansion and coalescence. With the increase of porosity, the instability of coal samples transitioned from tensile-shear brittle failure to tensile ductile failure, facilitating the formation of macroscopic cracks and sig-nificantly increasing their quantity and distribution range. Porosity-induced changes shifted the acoustic emission signals of coal sample from sudden and rapid evolution to a slower evolution. Tensile stress at the tip of pores drove the initiation and extension of microscopic tensile cracks. Higher porosity led to a broader distribution range and increased magnitude of tensile stress, resulting in numerous microscopic cracks initiation, propagation, and coalescence and leading to a larger extent of coal sample failure and an increased number of macroscopic cracks. The distribution and evolution of tensile stress within coal samples were significantly influenced by the characteristics of pore structure, which influencing the initiation, extension, and coalescence of microscopic cracks at pore tips. This research provides guidance for mine roadway drilling pressure relief to prevent rock bursts.

国家自然科学基金青年基金资助项目(52304090);中煤科工开采研究院有限公司面上资助项目(KCYJY–2023–MS–01);中煤科工开采研究院有限公司青年基金资助项目(KCYJY–2023–QN–04)

李建忠,魏炯,原贵阳,等.孔隙率对煤样力学性质及变形破坏特征的影响机制[J].采矿与岩层控制工程学报,2024,6(3):033033.

LI Jianzhong, WEI Jiong, YUAN Guiyang, et al. Study on the influence mechanism of porosity on the mechanical properties, defor-mation and failure characteristics of coal samples[J]. Journal of Mining and Strata Control Engineering, 2024, 6(3): 033033.