Fracture Mechanics for Heterogeneous Materials and its Application to Controlled Blasting and Splitting

虽然岩石通常被认为是一种非均质材料，但在断裂力学中，岩石通常被视为一种均质材料。本文分析和讨论了非均质性对岩石裂纹扩展的影响。(1)采用双扭试验研究了典型非均质岩石花岗岩亚临界裂纹扩展行为的各向异性。实验结果证实，花岗岩亚临界裂纹扩展具有各向异性，且与裂纹扩展方向有关。此外，在较低应力水平下裂纹扩展时，裂纹路径的几何形状变得更平滑。这些行为和特征是由取向微裂纹引起的。结果表明，非均质岩石的裂纹扩展是通过裂纹尖端附近微裂纹的连接以较低的断裂能进行的。(2)对部分泥质碎屑岩进行了矿物学检查、物性测量和湖泊耐久性试验，明确了除蒙脱石矿物学外，岩石的矿物组成和结构对岩石耐久性有很大影响。(3)提出了一种基于有限元法和断裂力学的非均质岩石数值模拟方法。分析了台阶爆破破岩破碎和破岩破碎的断裂过程，阐明了破岩破碎的机理。

Although the rock is generally considered to be a heterogeneous material, the rock is usually treated as a homogeneous material in the fracture mechanics. In this study, the influence of heterogeneity on the crack growth in rock was analyzed and discussed.(1) Double-Torsion test was performed to investigate the anisotropy of subcritical crack growth behavior in granite that is a typically heterogeneous rock. The experimental results confirmed that subcritical crack growth in granite was anisotropic and depended on the direction of the crack growth. Furthermore, the geometry of crack path becomes smoother in the case that the crack propagates with lower stress level. These behavior and characteristics are caused by the oriented microcracks. From these results, it is concluded that the crack growth in heterogeneous rock takes place with lower fracture energy by linking of mierocracks existing nearby crack tip.(2) Mineralogical examination, physical properties measurement and slake durability tests of some argillaceous clastic rocks have been carried out and it was made clear that the mineral composition and texture of rocks in addition to smectite mineralogy have a great influence in rock durability.(3) A numerical simulation method based on the finite element method and fracture mechanics for heterogeneous rock was proposed. Analyzing fracture processes of rock splitting by the breaker and rock fragmentation in bench blasting, the mechanism of splitting and fragmentation were clarified.