非均匀岩石破裂过程渗透率演化规律研究

STUDY ON PERMEABILITY EVOLUTION IN FAILURE PROCESS OF INHOMOGENEOUS ROCK

应用自主开发的数值模拟系统,通过数值试验,很好地描述了岩石破坏损伤演化过程中渗流场变化规律,包括岩石在应力-应变曲线不同阶段的渗透率演化规律、非均匀性对渗流场分布和渗透率的影响。结果表明,非均匀性对岩石的应力峰值强度、峰值前后渗透性演化规律及其破裂机制的影响十分明显。

The phenomena of progressive failure leading to the collapse of the rocks can be simulated well by author-developed software F-RFPA2D. The simulated permeability variation in stressed rocks agrees well with the experimentally obtained results. Numerical results demonstrate that the trend and magnitude of the permeability variation are controlled by the stress and the damage evolution developed in rocks. The stress induced evolution of flow properties,and the regions of both diminished and enhanced flow depend on whether the rock is in the linear-elastic,nonlinear,or post-failure portions of the stress-strain curve. In elastic deformation region,rock permeability reduces when the rock is compacted. The decrease rate of the permeability starts to slow down or gradually increases again when micro fractures begin to nucleate. Dramatic permeability increment occurs as soon as the macro fracture forms in the rock.