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

虽然岩石通常被认为是非均质材料，但在断裂力学中，岩石通常被视为均质材料。在这项研究中，非均匀性的岩石裂纹扩展的影响进行了分析和讨论。(1)采用双扭试验研究了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，并与裂纹扩展方向有关。在较低的应力水平下，裂纹扩展路径的几何形状变得更加平滑。这些行为和特征是由定向微裂纹引起的。结果表明，非均质岩石中裂纹的扩展是通过裂纹尖端附近微裂纹的连接在较低的断裂能下进行的。(2)通过对泥质碎屑岩的矿物学、物理性质测定和崩解耐久性试验，表明岩石的矿物组成和结构除蒙皂石矿物学外，对岩石的耐久性也有很大的影响。(3)提出了一种基于有限元和断裂力学的非均质岩石数值模拟方法。分析了台阶爆破中破碎器劈裂岩石和岩石破碎的断裂过程，阐明了岩石的劈裂破碎机理。

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.