In coal mining, rock strata are fractured under cyclic loading and unloading to form fracture channels. Fracture channels are the main flow narrows for gas. Therefore, expounding the flow conductivity of fracture channels in rocks on fluids is significant for gas flow in rock strata. In this regard, graded incremental cyclic loading and unloading experiments were conducted on sandstones with different initial stress levels. Then, the three-dimensional models for fracture channels in sandstones were established. Finally, the fracture channel percentages were used to reflect the flow conductivity of fracture channels. The study revealed how the particle size distribution of fractured sandstone affects the formation and expansion of fracture channels. It was found that a smaller proportion of large blocks and a higher proportion of small blocks after sandstone fails contribute more to the formation of fracture channels. The proportion of fracture channels in fractured rock can indicate the flow conductivity of those channels. When the proportion of fracture channels varies gently, fluids flow evenly through those channels. However, if the proportion of fracture channels varies significantly, it can greatly affect the flow rate of fluids. The research results contribute to revealing the morphological evolution and flow conductivity of fracture channels in sandstone and then provide a theoretical basis for clarifying the gas flow pattern in the rock strata of coal mines.

在煤炭开采中，岩层在循环加载和卸载的作用下破裂，形成裂隙通道。裂缝通道是气体的主要流动通道。因此，阐明岩石裂缝通道对流体的导流能力对于岩层气体流动具有重要意义。为此，对不同初始应力水平的砂岩进行了分级增量循环加卸载实验。然后，建立了砂岩裂缝通道的三维模型。最后，利用裂缝通道百分比来反映裂缝通道的导流能力。该研究揭示了裂隙砂岩的粒度分布如何影响裂隙通道的形成和扩展。研究发现，砂岩破坏后，大块体所占比例较小，小块体比例较高，对裂缝通道的形成贡献更大。裂隙岩石中裂隙通道的比例可以表明这些通道的导流能力。当裂缝通道的比例缓慢变化时，流体均匀地流过这些通道。然而，如果裂缝通道的比例变化较大，则会极大地影响流体的流速。研究成果有助于揭示砂岩裂隙通道的形态演化和导流能力，进而为明确煤矿岩层瓦斯流动规律提供理论依据。