The fragmentation of coal produces abundant coal gases and is presumed to be the defining characteristic of coal and gas outbursts. Knowing the mechanism of these catastrophic hazards is one of the most important breakthroughs in mining geology. In the outburst process, coal spallation represents a unique failure type and typically leaves behind a spallation area (with a series of fracture textures) in the coal seam. Revealing its features and formation mechanism is crucial in accurately interpreting the outburst process. In this study, we conducted a series of outburst experiments with different gases, including CO₂, N₂, and He. We establish that a spallation area can develop spontaneously during CO₂ and N₂ tests, whereas an outburst caused by He tests (even under stressed conditions) does not produce a spallation area. That is, the spallation area cannot be observed in non-absorbable gas outbursts. We, therefore, focus on the role of coal gas in spallation and propose a viable mechanism to explain its formation. During the outburst development stage, the influence of gas ad-/desorption is critical, as it controls the width of the spallation area and the spallation thickness. In contrast, stress is not a necessary condition. Whether a spallation area will be produced is particularly determined by the generation of a sufficient internal pressure gradient. Moreover, because of gas desorption, the total outburst energy can be increased by 1.84–5.30 times; and the mean outburst propagation velocity and the mean frequency of coal spallation ejected can be enhanced by 0.38–8.76% and 1.28–12.07%, respectively. Consequently, the destructiveness of outbursts depends on the contribution of desorbed gas.

煤的破碎会产生大量的煤气，被认为是煤和瓦斯突出的决定性特征。了解这些灾难性灾害的机制是采矿地质领域最重要的突破之一。在突出过程中，煤层散裂代表了一种独特的破坏类型，通常会在煤层中留下散裂区（具有一系列裂缝纹理）。揭示其特征和形成机制对于准确解释爆发过程至关重要。在这项研究中，我们对不同的气体进行了一系列的爆发实验，包括 CO ₂、N ₂和 He。我们确定散裂区域可以在 CO ₂和 N ₂期间自发发展测试，而由 He 测试（即使在压力条件下）引起的爆发不会产生散裂区域。也就是说，在不可吸收的瓦斯爆发中无法观察到散裂区域。因此，我们关注煤气在散裂中的作用，并提出一种可行的机制来解释其形成。在突出发展阶段，气体吸附/解吸的影响至关重要，因为它控制着散裂区域的宽度和散裂厚度。相比之下，压力不是必要条件。是否会产生散裂区，具体取决于是否产生足够的内部压力梯度。此外，由于气体解吸，总爆发能量可提高1.84-5.30倍；平均突出传播速度和平均喷出煤层散频率可分别提高0.38-8.76%和1.28-12.07%。因此，爆发的破坏性取决于解吸气体的贡献。