层状岩石细观构造表征及劈拉受载各向异性行为研究

层状岩石结构内部矿物之间的定向排列与胶结作用形成不同构造方向的细观结构，使岩石变形破裂及其力学性能存在明显的各向异性。该文以板岩为研究对象，通过构建空间相关函数，建立可表征不同片理方向的岩石细观颗粒离散元模型。基于细观力学参数反演，针对不同片理角度（θ）的巴西劈裂试验开展数值仿真分析，对板岩的各向异性行为进行了研究。结果表明，由于岩石受内部片理构造的影响，在劈拉荷载作用下，呈现三种破坏模式，当θ ≤ 30°时主要发生矿物颗粒之间的拉伸破坏，当θ=45°~75°时为剪切与拉伸共同作用产生的破坏，当θ >75°时为沿着片理面的拉伸破坏；岩样破坏所耗能量及劈拉强度随片理角度的增大而逐渐降低。该文提出的方法能较好地模拟层状岩石的各向异性力学特征及变形破裂规律，与试验结果表现出良好的一致性。

MESOSCALE STRUCTURE RECONSTRUCTION AND ANISOTROPIC BEHAVIOR MODELING OF LAYERED ROCK UNDER SPLITTING-TENSILE LOADING

Various meso-scale representations of layered rock are formed by the directional arrangement and cementation of the minerals on a layered structure, which is obviously anisotropic in the mechanical behavior. This study presents a meso-scale particle discrete element model, which can demonstrate the meso-scale structure of slate by introducing a spatial correlation function. Based on the derivation of mechanical parameters on the meso-scale, the numerical simulations for slate Brazilian splitting tests with different bedding angles (θ) are conducted to investigate the anisotropic behavior. The simulation shows that there are three typical failure modes due to the various arrangements of bedding structures, including tensile failure at θ ≤ 30°, combined shear and tensile failure at θ=45°~75°, and splitting-tensile failure at θ>75°. The splitting tensile strength and the fracture energy decrease with the increase of θ. The proposed method is able to describe the anisotropy characteristics and the deformation-fracture behavior for layered rocks, which is in a good agreement with corresponding experiments.