煤基质内部富含复杂孔隙，为瓦斯提供了大量的存储空间和运移通道。孔隙内的瓦斯流进裂隙需要经过扩散过程，基质尺度在一定程度上决定了扩散到裂隙的阻力，影响着瓦斯扩散的难易程度。研究以瓦斯扩散与煤基质尺度内在联系为出发点，通过处理颗粒煤解吸瞬态过程数据得到不同解吸时刻煤的双重孔隙结构内的瓦斯浓度与质量交换速率的定量关系，结合时变扩散系数对基质形状因子进行计算，提出了基于瞬态扩散的颗粒煤基质尺度计算方法，并进行了试验验证。结果表明：与较小颗粒煤相比，保存完整基质形态的大颗粒煤初始扩散系数基本不变，因此初始扩散系数的值在一定程度上可以表征基质的破坏程度。基质形状因子随解吸时间的延长而减小，可划分为急降阶段、缓降阶段和稳定阶段，其中稳定阶段基质形状因子能够准确反映扩散后期拟稳态下的基质形态，最适合求解基质尺度。该方法可以反映颗粒煤粉化损伤过程中的基质尺度变化规律，为解释扩散极限粒径的存在提供依据。糯东煤样的3种试验粒径基质尺度随煤颗粒的增大而增大，分别为0.059、0.287、0.457 mm，并且在大粒径范围具有无差性，证明了该方法的准确性。颗粒煤基质尺度可以用来修正K₁值的计算参数，使瓦斯损失量计算模型在粉化程度高的煤样中同样具有很好的适用性。

The coal matrix provides large capacity place for methane storage and migration by its inner complex pore structure. Gas migration from the coal matrix system to the fracture involves the methane diffusion. Therefore, the scale of the matrix determines to some extent the resistance to diffusion into the fissure, influencing the difficulty of methane diffusion out of the matrix. Taking the intrinsic connection between gas diffusion and coal matrix scale as the starting point, a calculation method of coal matrix scale based on transient diffusion is proposed with the time-varying diffusion coefficient as parameters for calculating matrix shape factor, in which the quantitative relationship between methane concentrations and mass exchange rate within the dual pore structure of coal at different desorption moments is obtained by processing the data of the desorption transient process of particle coal. The experiment validation results show that the initial diffusion coefficient is essentially constant for coals with preserved intact matrix forms compared to smaller particle coals so the value of the initial diffusion coefficient can characterize the degree of matrix destruction to some extent. The value of the matrix shape factor decreases with the extension of desorption time and can be specifically divided into sharp-decreasing phase, slow-decreasing phase and stable phase, among which the stable phase matrix shape factor can accurately reflect the matrix shape in the proposed steady state at the late stage of diffusion and is most suitable for solving the matrix scale. The method can reflect the change pattern of matrix scale variation during granular coal pulverization damage process to provide a basis for explaining the existence of diffusion limit particle size and shows the non-differentiation in the large particle size range, which also proved the accuracy of the method. The three experimental particle size matrix scales for the Nuodong coal samples were calculated to increase with increasing particle size, 0.059 mm, 0.287 mm and 0.457 mm, respectively. The particle coal matrix scale can be used to correct the calculation parameters of K₁ values, rendering the gas loss calculation model equally applicable in coal samples with a high degree of pulverization.