The macroscopic mechanical characteristics and microscopic pore structure evolution were investigated in gas-bearing coal subjected to creep loading superimposed with drop hammer impact loads, under different gas adsorption pressures, creep stress levels, and impact load magnitudes. The results show that, as gas adsorption pressure, creep stress level, and impact load increase, the peak strength of coal specimens decreases, while the peak axial strain and radial strain increase. Low-temperature liquid nitrogen adsorption tests demonstrated that the maximum adsorption capacity, total specific surface area, total pore volume, and the proportion of specific surface area and pore volume of micropores in intermediate-sized coal specimens decrease with increase in the three variables. In contrast, the proportion of specific surface area, total proportion of pore volume, and the fractal dimension of transition pores and mesopores increase, indicating a transformation of micropores into transition pores and mesopores. Importantly, a strong linear correlation was established between the damage rate of coal specimens and the proportion of micropore specific surface area, pore volume, and pore fractal dimension. These findings lay the groundwork for developing a macro–micro combined damage and failure constitutive model for gas-bearing coal subjected to superimposed dynamic and static loads, thereby enhancing the theoretical framework of rock dynamics.

研究了在不同瓦斯吸附压力、蠕变应力水平和冲击载荷大小下，在蠕变载荷叠加落锤冲击载荷作用下，含瓦斯煤的宏观力学特征和微观孔隙结构演化。结果表明，随着瓦斯吸附压力、蠕变应力水平和冲击载荷的增加，煤试件的峰值强度降低，而峰值轴向应变和径向应变增大。低温液氮吸附试验表明，中等尺寸煤样的最大吸附量、总比表面积、总孔容以及微孔比表面积与孔容的比例均随着三个变量的增大而减小。相比之下，过渡孔和中孔的比表面积比例、总孔容比例和分形维数增加，表明微孔向过渡孔和中孔转变。重要的是，煤样的损伤率与微孔比表面积、孔体积和孔隙分形维数的比例之间建立了很强的线性相关性。这些发现为开发动态和静态叠加荷载作用下的含瓦斯煤的宏观-微观联合损伤和破坏本构模型奠定了基础，从而增强了岩石动力学的理论框架。