通过对济宁三号煤矿岩样进行现场采取和室内试验分析,探究对开采有威胁的3 煤层顶板砂岩和红层的渗透率特征.试验结果表明,中粗砂岩的渗透率最大,泥岩样的渗透率相对较小;应力对岩石的渗透率有很大的影响,主要体现在节理的法向闭合和剪胀效应,其中应力剪胀能显著地改变岩石节理的渗透性;岩石应变渗透率曲线,表现出渗透率峰值“滞后”的特点;在岩石处于弹塑性阶段时候,渗透率的变化剧烈且具有不可预测性,然而岩石渗透率与体积应变有很好的一致性.通过对实验结果的归纳总结,本文将岩石在全应力应变过程中渗透率变化划分成5 个阶段:微裂隙压密闭合阶段、微裂隙随机扩展阶段、裂隙扩展贯通阶段、裂隙错动充分发育阶段和裂隙二次闭合阶段.
The characteristics of permeability of the sandstone of coal seam 3 roof and red bed threatening the mining activities were analyzed by spot sampling and laboratory experiments on rock samples of No.3 Jining coal mine. The test results indicated that permeability of medium-coarse sandstone is the biggest, but that of mudstone is the smallest; Stress has great influence on the permeability in different ways which include closure in the normal direction and dilatancy effect of joints, stress dilatancy changes the permeability of rock significantly; strain-permeability curve of rocks displays lag of permeability peak value. The rock permeability changes acutely and unpredictably at phase of elastic-plasticity, however, there is a good agreement between permeability and volumetric strain. By summarizing and analyzing the experimentation results, permeability variation can be divided into 5 stages: stage of consolidation and closure of microfissures, stage of random expansion of microfissures, stage of propagation and cutthrough of fissures, stage of diastrophsm and sufficient development of fissures, and stage of secondary closure of fissures.