非均匀岩石介质单轴压缩强度及变形破裂规律的数值模拟

以有限差分法(FDM)为计算框架，利用Weibull分布描述细观单元弹性模量和单轴抗压强度的分布特征，采用弹塑性应变软化本构模型描述细观单元的力学响应，进而建立一种模拟非均匀岩石介质破裂的数值模型。采用该数值模型探讨了单轴压缩时细观均质度m及细观结构对数值试样宏观特性的影响。结果表明，（1）随着细观均质度提高，数值模型的非线性特征逐渐减弱，脆性逐渐增强；宏观峰值强度及弹性模量逐渐增大，峰值强度与lnm呈线性关系，而弹性模量与1/m为线性关系；数值试样表现出由塑性流动破坏至剪切破坏进而为张拉破坏的破坏模式；（2）当细观均质度一定时，细观结构或细观单元空间排列是决定岩石力学行为波动性的主要因素；应力–应变曲线峰前阶段对细观单元的空间排列不敏感，但峰值强度附近及峰后阶段对细观单元的空间排列比较敏感。

Numerical simulation of uniaxial compressive strength and failure characteristics in nonuniform rock materials

A numerical model based on finite difference method(FDM) in FLAC3D is proposed to simulate the fracture of nonuniform rock materials. Weibull distribution is introduced to describe the distribution characteristics of elastic modulus and uniaxial compressive strength in each mesoscopic element which exhibits elastoplastic strain softening mechanical response. Then, this numerical model is used to investigate the effect of the mesoscopic nonuniformity and mesostructure on the macroscopic properties of numerical specimens under uniaxial compression. The results show that: (1) With the improvement of mesoscopic nonuniformity, the nonlinear characteristics of the numerical specimen gradually weaken and the brittleness gradually increases. Besides, the macroscopic peak strength and elastic modulus are linearly increased with ln(m) and 1/m respectively. Meanwhile, the failure mode of numerical specimens changes from plastic flow failure to shear failure and further to tensile failure. (2) When the mesoscopic nonuniformity indices keep constant, the mesostructure or mesoscopic elements space arrangement is the main factor that determines the fluctuation of rock mechanical behavior. Both the near-peak and post-peak phases of the stress-strain curve are sensitive to the spatial arrangement of the mesoscopic elements; but the pre-peak phase is opposite.