不同浸泡环境下压力水浸煤岩蠕变损伤劣化特征研究
Characteristics of creep damage and degradation of coal and rock under pressurized water-immersed in various immersion conditions
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摘要: 为探究分级加载作用下煤岩损伤演化对采空区稳定性的影响, 以济南市某矿煤样为研究对象, 开展围压作用下经不同水质浸泡后的分级加载蠕变试验, 分析研究了煤岩在浸水条件下的结构演化与力学损伤劣化机理。结果表明: 在分级加载与压力水浸的共同作用下, 水−岩作用加速导致煤岩内部损伤增大, 与蒸馏水相比, 因矿井水内部含酸性矿物, 加速了煤岩内部裂纹的扩展和颗粒间的摩擦作用; 煤岩试件内部平均黏土矿物的含量下降最大时, W和MW组分别减少了45.92%和62.79%; 因矿井水的软化作用更强, MW组试件的振铃计数波动及密集度均高于W组, 6组试件受损前均存在振铃计数“间歇期”。随着加载应力的增加, 试件内的损伤累积速率更快, 各组试件的损伤变量、弹性能和耗散能均呈递增的趋势; 与干燥试件相比, 压力水浸下试件的孔隙率和概率熵均增加, W和MW组试件的平均孔隙率分别上升了119.87%、243.59%, 平均概率熵上升了49.51%和95.14%。研究结果对压力水作用下采空区稳定性设计具有重要的参考意义。Abstract: This study is aimed at exploring the influence of creep-induced damage evolution of coal samples on goaf stability under stepped loading. To achieve this aim, coal samples from a mine in Jinan City were immersed in distilled water (W) and mine water (MW) first and then subjected to creep tests under stepped loading and confining pressure. On this basis, the structural evolution and mechanical deterioration mechanisms of water-immersed coal were systematically analyzed. Results demonstrate that the joint action of stepped loading and pressurized water immersion synergistically intensifies water-rock interaction, increasing internal damage. Acidic components in MW further accelerate crack propagation and inter-particle friction compared to W. Maximum reductions in average clay mineral content reach 45.92% and 62.79% for W and MW, respectively. MW samples also exhibit higher fluctuation amplitude and signal density of acoustic emission (AE) ring count due to their stronger softening effect, with an AE quiescence phase observed before failure in all six samples. With the rise of loading stress, damage accumulation accelerates, accompanied by increases in damage variables, elastic energy, and dissipated energy within the samples. Porosity and probability entropy increase significantly under pressurized water immersion—by 119.87% and 243.59% for average porosity in W and MW and by 49.51% and 95.14% for average probability entropy, respectively. These findings reveal critical insights into the design of goaf stability under pressurized water conditions.
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