Mechanical properties and energy migration mechanisms of coal-rock composite with different height ratios under gas-containing conditions

作者：Penghui Guo, Keming Yang, Jiazhuo Li, Xiaolou Chi, Wenjie Liu, Changcheng Wang, Xianghui Wu · 发表于：Journal of Materials Research and Technology · 年份：2025 · DOI：10.1016/j.jmrt.2025.05.036 · 被引用次数：8 · 研究领域：Rock Mechanics and Modeling、Geotechnical and Geomechanical Engineering、Coal Properties and Utilization

To study the influence of coal thickness on gas-containing rock-coal-rock composites' failure mechanisms, uniaxial loading tests under gas-solid coupling conditions were conducted on composites with varying thickness ratios. The research examined their mechanical properties, microscopic damage evolution, fractal dimensions, and acoustic emission (AE) characteristics. Theoretical analyses revealed gas-induced deterioration mechanisms and interfacial effects, while an energy migration model was established to elucidate energy transfer processes between coal and rock components. The results indicate that as coal thickness increases, the average fractal dimension of surface cracks in the composite decreases, accompanied by reductions in uniaxial compressive strength and elastic modulus, approaching values typical of standard coal samples. This confirms that the weak structural (coal) component dominates the overall strength of the composite. In gas-containing rock-coal-rock composites, increased coal thickness shifts the microscopic failure mode of coal components from brittle to predominantly ductile fracture, with fracture surfaces transitioning from smooth to rough textures. Gas deteriorates the overall strength of the composite, intensifying the “interface effect"-induced weakening of sandstone while diminishing its coal-strengthening function. Gas accelerates coal's entry into plastic failure and prematurely terminates the elastic energy storage phase in rock, thereby reduci...