The coal matrix exhibits significant heterogeneity at the micro-scale. In this study, a heterogeneous mechanical model of coal matrix from different coal ranks was constructed by using nanoindentation. Additionally, a fluid-solid coupling model was developed to consider matrix shrinkage and stress sensitivity, enabling the incorporation of porosity changes during methane diffusion. The methane concentration and matrix deformation characteristics in the simulation area at different times was obtained. The effects of matrix shrinkage and stress sensitivity on porosity changes and matrix deformation were compared. And the deformation of the matrix under different micromechanical properties was compared. The findings indicate that the nanoindentation method effectively characterizes the micromechanical heterogeneity of coal matrices. Furthermore, during the diffusion process, we observed an initial increase followed by a decrease in matrix deformation, with matrix shrinkage leading to more pronounced deformation. Notably, harder coal matrices exhibited reduced deformation. This study enhances the understanding of the dynamic changes in the matrix during coalbed methane extraction.

中文翻译：

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通过纳米压痕考虑微机械性能的异质性煤基质中的甲烷扩散

煤基质在微观尺度上表现出显着的非均质性。在本研究中，利用纳米压痕技术构建了不同煤阶煤基质的非均质力学模型。此外，还开发了流固耦合模型来考虑基体收缩和应力敏感性，从而能够纳入甲烷扩散过程中的孔隙率变化。获得了模拟区域不同时间的甲烷浓度和基体变形特征。比较了基体收缩和应力敏感性对孔隙率变化和基体变形的影响。并对不同微观力学性能下基体的变形情况进行了比较。研究结果表明，纳米压痕方法有效地表征了煤基质的微观力学非均质性。此外，在扩散过程中，我们观察到基体变形最初增加，随后减少，基体收缩导致更明显的变形。值得注意的是，较硬的煤基质表现出变形减少。这项研究增强了对煤层气开采过程中基质动态变化的理解。