基于脆性模量系数的岩石应变软化及渗透率演化模型

Strain softening and permeability evolution model based on brittle modulus coefficient

岩石峰后应变软化力学行为及渗透率演化规律是岩石工程稳定性和安全性分析的基础。在三轴实验基础上分析了围压对岩石峰后应变软化力学行为的影响规律,提出了描述围压对岩石峰后脆性影响的新参数,即脆性模量和脆性模量系数,分析了脆性模量的物理意义和脆性模量系数方法的应用范围。基于脆性模量系数,结合强度退化指数、扩容指数、FLAC中的SS模型和体积应变增透率,建立了考虑围压影响的岩石应变软化模型和渗透率演化模型。利用本文模型较好地模拟再现了不同围压下Gebdykes白云岩变形和巴里坤砂岩渗透率的演化过程,验证了本文模型的合理性。将本文模型应用于某煤层开采过程中围岩变形和渗透率的动态演化预测,结果表明随着煤层开采,采动应力引起围岩变形、破坏,其渗透率也随之动态变化,本文模型能较好地再现煤层开采过程中围岩的渗透率动态演化规律。

The scientific predictions of the strain softening and permeability evolution behaviors of rock are the basis of the stability and safety analysis in rock engineering. Through the analysis on the tri-axial compression tests data,the laws of the effects of confining pressure on the strain softening mechanical behaviors of rock are presented.To describe the effects of the confinement on the brittleness of peak-post rock,the brittle modulus and the brittle modulus coefficient are proposed.The physical meanings of the brittle modulus and the application scope of the brittle modulus coefficient are also described.Adopting the brittle modulus coefficient,combined with the strength degradation index,dilatancy index,SS model in FLAC and the method of the enhanced permeability of volumetric strain,a new strain softening and permeability evolution model has been developed.Using FLAC software,the deformation and permeability evolution behaviors under the different confining pressures of Gebdykes dolomite and Balikun sandstone are better numerically modeled,and the model proposed in this paper is proved to be valid.Lastly the model proposed in this paper is used to predict the permeability dynamic evolution of overburden rock due to mining.The results show with the work face advance the deformations and failures of overburden rock appear due to mining disturbance stresses,and correspondinglythe permeability of rock dynamically changes.The process is better numerically modeled by the model proposed in this paper.