基于LBM方法的裂隙煤岩应力–应变过程中渗流特性研究

为了研究受载裂隙煤岩的渗流特性,利用工业CT扫描和图像处理技术,重建可用于LBM数值模拟的三维裂隙场,开展受载煤岩在不同加载阶段的CT扫描与渗流实验。试验测试和数值模拟研究的结果表明:LBM模拟结果的平均误差为18.72%,与渗流实验结果具有良好的一致性,表明LBM模拟方法具有较好的准确性和有效性;LBM模拟结果的准确性与煤岩内部裂隙发育程度有关,裂隙愈发育、连通性愈好,LBM模拟结果愈准确;裂隙煤岩的渗透性与其内部裂隙场的压缩和扩展密切相关;煤岩渗透性在压密阶段和弹性变形阶段不断降低,在弹性变形后期和屈服变形阶段增大,峰值强度后的卸压破坏阶段达到最大。研究结果验证了LBM数值模拟在描述裂隙煤岩渗透性的可行性,为今后受载裂隙煤体内部瓦斯流动机制、流动规律和煤层瓦斯抽采过程的可视化研究提供了可靠途径。

Seepage characteristics of loaded fractured coal based on LBM Method

In order to study the seepage characteristics of loaded fractured coal,the three-dimensional fracture field used for LBM numerical simulation was reconstructed by the industrial CT and image processing technology,and the CT scanning and seepage experiments of loaded coal at different loading stages were carried out. The results show that the average error of LBM simulation results is 18.72%,which is in good agreement with the test results,indicating that the LBM simulation has good accuracy and effectiveness. The accuracy of LBM simulation results is related to the development degree of cracks in coal. The more cracks develop,the better the connectivity is and the more accurate the LBM simulation results are. The permeability of fractured coal is closely related to the compression and expansion of internal fracture field. The permeability of coal decreases continuously in the compaction stage and the elastic deformation stage while increases in the late elastic deformation stage and the yield deformation stage,and reaches the maximum in the pressure relief failure stage after the peak strength. The study results verify the feasibility of LBM numerical simulation in describing the permeability of fractured coal,and provide a reliable way for visualization research on the internal gas flow mechanism,flow law and coal seam gas extraction process of loaded fractured coal in the future.