水围压环境下煤的冲击破裂特征及能量耗散规律试验研究

Experimental study on impact fracture characteristics and energy dissipation law of coal under water confining pressure

  • 摘要: 为研究三轴条件下煤岩体真实冲击破裂过程及能量耗散规律,基于自主研发的多场耦合霍普金森压杆(SHPB)试验系统,开展煤样的可视化试验,研究不同水围压条件下煤样裂纹演化特征,分析煤样动力学指标与冲击速度、应变率和水围压之间的关系,阐明水围压作用对煤样能量吸收—转化—释放的影响特征。结果表明:水围压环境中,煤体的动态强度呈现明显的应变率效应。水围压与煤体的动态强度之间具有良好的二次函数关系,且随水围压的升高煤样的破坏应变呈递减趋势,破裂模式由轴向劈裂破坏向压剪破坏转变。冲击载荷越大,输入煤体的总能量和用于损伤变形的耗散能越高,煤体的变形程度也愈严重。随着水围压的增大,总输入能呈现逐渐增加的变化趋势,意味着煤体发生破坏时需要外界输入更多能量。

     

    Abstract: To investigate the actual dynamic fracture process and energy dissipation mechanisms of coal under triaxial loading conditions, a visual experimental study was conducted using a self-developed multi-field coupled Split Hopkinson Pressure Bar (SHPB) testing system. This research systematically examined crack evolution characteristics in coal samples under varying water confining pressure conditions. The relationships between dynamic mechanical parameters (impact velocity, strain rate, and water confining pressure) were quantitatively analyzed, along with the influence of water confining pressure on energy absorption, conversion, and release processes during coal failure. The research results show that the dynamic strength of coal shows obvious strain rate effect under water confining pressure environment. There is a good quadratic function relationship between water confining pressure and the dynamic strength of coal mass, and the failure strain of coal samples shows a decreasing trend with the increase of water confining pressure. With the increase of water confining pressure, the fracture mode of coal mass will change from "axial splitting failure" to "compression-shear failure". The greater the impact load, the higher the total energy input to the coal body and the dissipated energy used for damage and deformation, and the more serious the deformation of the coal body. With the increase of water confining pressure, the total input energy shows a trend of gradual increase, and more energy is required from the outside when the coal body is damaged.

     

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