College of Mining, Guizhou University
National & Local Joint Laboratory of Engineering for Effective Utilization of Regional Mineral Resources from Karst Areas, Guizhou University
Guizhou Key Laboratory of Comprehensive Utilization of Non-metallic Mineral Resources
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University

随着煤矿开采深度不断增大，煤岩力学性质响应和瓦斯运移机制变得异常复杂。为探究工程上先抽后采一体化作业下煤岩损伤演化规律和瓦斯渗流机制，以重庆松藻煤矿K2煤层型煤试样为研究对象，利用含瓦斯煤热−流−固耦合三轴伺服渗流装置，对同一试件先后进行了降孔隙压力渗流试验和三轴压缩−渗流试验。根据弹塑性理论，推导表征煤岩全应力应变关系的统计损伤本构模型，进一步构建考虑损伤作用下煤岩渗透率模型。研究结果表明：在降孔隙压力渗流试验中，恒定外应力条件下的煤岩渗透率随孔隙压力降低呈现出先平缓上升后急剧上升趋势。在此过程中，煤岩渗透率变化受有效应力和瓦斯解吸相互竞争影响；在三轴压缩−渗流试验过程中，不同围压下煤岩变形阶段特征基本相似，随着围压增大，煤岩力学性质得到强化。煤岩渗透率曲线随轴向应变增大呈负指数函数变化；损伤变量曲线和塑性应变曲线随轴向应变增大均呈现先缓慢升高后急剧升高趋势，损伤演化过程与煤岩变形破坏各阶段全应力应变曲线相对应；通过与试验数据对比验证所建损伤本构模型和渗透率模型的合理性，表明模型能够较为准确地反映煤岩变形阶段特征及瓦斯渗流规律。

With the continuous increase of coal mining depth, the response of coal mechanics and the mechanism of gas migration have become extremely complicated. In order to explore the coal damage evolution and gas seepage mechanism under the integrated operation of first extraction and subsequent mining in engineering, the K2 coal seam briquette sample of Chongqing Songzao Coal Mine was used as the research object. Using the triaxial servo seepage device of thermal-fluid-solid coupling of gas-bearing coal, the reduced pore pressure seepage test and the triaxial compression-seepage test were successively carried out on the same specimen. According to the elasto-plasticity theory, a statistical damage constitutive model that characterized the whole stress-strain relationship of coal was derived, and the permeability model of coal under consideration of damage was further constructed. The results of the research shown that, in the reduced pore pressure seepage test, the permeability of coal under constant external stress shown a trend of first rising gently and then rising sharply with the decrease of pore pressure. In this process, the change of coal permeability was affected by the competition between effective stress and gas desorption. In the process of the triaxial compression-seepage test, the characteristics of coal deformation stages under different confining stresses were basically similar. As the confining stress increased, the coal mechanics properties were strengthened. The coal permeability curve changed as a negative exponential function with the increasing axial strain . The damage variable curves and plastic strain curves shown a trend of first rising slowly and then rising sharply with the increase of axial strain, the damage evolution process was corresponded to the whole stress-strain curve of each stage of coal deformation and failure. The rationality of the constructed damage constitutive model and permeability model were verified by comparison with test data, which shown that the model can more accurately reflect the characteristics of coal deformation stages and the law of gas seepage.

国家自然科学基金资助项目(52064007)；贵州省科技厅−贵州大学科技合作计划资助项目(黔科合基础-ZK〔2021〕重点052)

付佳乐，李波波，高　政，等. 不同孔隙压力和围压下煤岩渗透及力学特性试验研究[J]. 煤炭科学技术，2023，51（8）：150−159

FU Jiale，LI Bobo，GAO Zheng，et al. Experimental study on permeability and mechanical properties of coal under different pore pressure and confining pressure[J]. Coal Science and Technology，2023，51（8）：150−159