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Abstract：
This paper presents the investigation of the dynamic mechanical properties of coal rock under complex stress conditions at depth, based on the improved Separate Hopkinson Pressure Bar Test System. A total of 15 groups of coal samples were used to perform dynamic impact tests under different conditions. The changing rules of dynamic strength, crushing, fractal dimension and damage modes of coal under different stress conditions were analyzed. A total of nine groups of coal samples were selected for numerical simulation using ANSYS/LS-DYNA. The results show that: (1) The stress-strain curves of coal specimens under different strain rates, different confining pressures and axial pressures have basically the same trend and the curves show a certain jump forward. (2) The peak dynamic stress of the coal specimens increased linearly with the increase of strain rate and confining pressure, and the ambient pressure limited the expansion of internal cracks of the coal specimens under impact loading. Based on the experimental and simulated data, the maximum relative errors between the experimental and simulated data were determined to be 2.9578% for Group A, 6.177% for Group B, and 6.382% for Group C, respectively. (3) The damage modes of the coal samples under the three-dimensional dynamic-static combined loading were mainly \"X\" type and \"conical\" shear damage. The fractal dimension increases with the increase of strain rate, decreases with the increase of confining pressure, and first decreases and then increases with the increase of axial pressure. This research achievement can provide theoretical support for the prevention of dynamic disasters in deep coal mine engineering.
摘要：
本文研究了在深部复杂应力条件下煤岩的动态力学特性,基于改进的分离式霍普金森压杆测试系统。共使用15组煤样在不同条件下进行动态冲击试验。动态强度的变化规律，压碎,分析了不同应力条件下煤的分形维数和损伤模式。采用ANSYS/LS-DYNA共选取9组煤样进行数值模拟。结果表明:(1)煤样在不同应变率下的应力-应变曲线,不同的围压和轴压具有基本相同的趋势，曲线表现出一定的向前跳跃。(2)煤样动态应力峰值随应变速率和围压的增加呈线性增加,和环境压力限制了冲击载荷下煤样内部裂纹的扩展。根据实验和模拟数据，A组的实验数据和模拟数据之间的最大相对误差确定为2.9578%，B组6.177%，C组为6.382%，分别。(3)煤样在三维动静联合加载下的损伤模式主要为“X”型和“锥形”剪切损伤。分形维数随着应变率的增加而增加,随着围压的增加而减小，随着轴向压力的增大,先减小后增大。该研究成果可为煤矿深部工程动力灾害的防治提供理论支持。
