岩石变形与渗透率演化关系研究

Study on the Evolution Relationship of the Deformation Mechanism and Permeability of Underground Rock

针对带压开采煤层底板岩层阻水性问题,进行底板岩体试样伺服渗透试验,分析了岩体试样渗透率与变形破坏演化相互关系。结果表明,全应力-应变过程岩样渗透率可划分为原始空隙渗透率和加载破坏渗透率两种,在压密-弹性段内,岩石的渗透率多表现为原始空隙渗透率,稳定破裂-裂纹扩展段内,则多表现为加载破坏渗透率;岩石突增点处应力、应变为峰值点处应力、应变的60%~80%之间,大多数岩石渗透率峰值出现在岩石的峰后阶段,部分出现在岩石峰值点处,少数的岩石渗透率峰值存在于岩石峰值强度之前,且多为软岩;灰岩类和砂岩类岩石变形破坏比泥质岩类岩石更为均匀,用渗透率突增点强度、应变分别与峰值强度、应变的比值或渗透率峰值点处应变与应力峰值点处应变的比值能较好反映岩石渗透率变化规律。

According to the impermeability of the floor strata in mining under pressure, the permeability test of the specimen was carried. Considering the relation between permeability-strain curve and rock failure process, the relationship among permeability, strain and stress of rock was analyzed based on the permeability-strain curves and permeability-stress curves under complete stress-strain path. The result shows that the permeability of the specimen can be divided into the original void permeability and loading failure permeability. The original void permeability mainly appeared at the compaction-elastic stage and the loading failure permeability is mainly at the stable and unstable development stage. The stress and strain at the sudden increase point is the 60% to 80% of the peak point. For the most rocks, the permeability peak is at the post-peak stage, some at the peak point, and a few at the pre-peak stage, which is the soft rocks mostly. The deformation and failure of the argillaceous rocks is more serious than the limestone and sandstone rocks. The ratio of the stress and strain at the sudden increase point and the peak point or the ratio of the strain at the maximum permeability and the sudden increase point of the permeability can better reflect the law of the changes of permeability.