脆性岩石变形机制与渗透率关系研究

Study on the Relationship of the Brittle Deformation Mechanism and Permeability of Rocks

为研究脆性岩石变形机制与渗透率-应变的关系,根据脆性岩石应力-应变和渗透率-应变关系曲线分析指出:脆性岩石经压密、弹性变形和非稳定破裂后,内部微裂隙出现丛集式发展,且不断合并、贯通,导致微观结构发生明显变化,使渗透率在临界破坏点处急剧增大;当岩石宏观破坏后,内部结构面上的岩桥或凸起体部分被剪断或磨平,使得岩石强度随变形突然下降,此时渗透率到达峰值。结合重整化群理论分析表明,脆性岩石在应力-应变曲线拐点处应变和渗透率峰值点处应变对应、临界破坏点处应变和渗透率急剧增大点处应变对应。通过试验研究和实例统计分析,验证了结论的合理性。

In order to study the relationship of the brittle deformation mechanism and permeability of rocks, the curves of stress- strain and permeability-strain of rocks were analyzed. The results indicate that the permeability of rocks increases rapidly at the critical failure point because of the significant changes of the micro structure that resulted from the cluster grouping, mergence and transfixion of the internal micro fissure with the compaction, elastic deformation, and progressive failure. The peak permeability is reached when a sudden decrease of rock strength with the deformation occurs, but has a certain residual strength that may be caused by the rock bridges or asperities on the internal structural plane which are ruptured partially or completely after macroscopic failure behavior of rocks. The strain at the critical point and turning point on a stress-strain curve can be analogized as those corresponding to the strain at the rapidly increased point and the peak point on the permeability-strain curve according to the renormalization theory. The conclusions are reasonable by the experimental studies and examples of statistical analyses.