Size effect of fracture characteristics for anisotropic quasi-brittle geomaterials
Size effect of fracture characteristics for anisotropic quasi-brittle geomaterials
复制标题
各向异性准脆性岩土材料断裂特性的尺寸效应
DOI：
10.1016/j.ijmst.2022.11.004
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发表时间：
--
影响因子：
11.8
通讯作者：
Wang Jun
中科院分区：
文献类型：
--
作者：
Li Cunbao;Yang Dongchao;Xie Heping;Ren Li;Wang Jun
了解各向异性岩土材料断裂机制所表现出的尺寸效应对工程实践具有重要意义。通过系统的尺寸效应断裂试验，分析了岩土材料的名义强度、表观断裂韧度、有效断裂能和断裂过程区尺寸的各向异性特征。结果表明，随着层面倾角的增大，岩石的名义强度和表观断裂韧性均呈下降趋势。试样尺寸越大，名义强度越小，表观断裂韧性越大。当层理倾角从0°增大到90°时，有效断裂能和有效断裂带尺寸均呈现先减小后增大的复杂变化过程，并以45°层理倾角为界。在不考虑岩土材料固有各向异性的情况下，基于能量的尺寸效应定律可以预测岩土材料的名义强度和表观断裂韧性，表明岩土材料具有明显的准脆性特征。理论分析表明，只有当脆性数大于10时，才能用线弹性断裂力学计算真实断裂韧度和能量耗散，否则应采用尺寸效应试验确定断裂参数。
Understanding the size effect exhibited by the fracture mechanism of anisotropic geomaterials is important for engineering practice. In this study, the anisotropic features of the nominal strength, apparent fracture toughness, effective fracture energy and fracture process zone (FPZ) size of geomaterials were first analyzed by systematic size effect fracture experiments. The results showed that the nominal strength and the apparent fracture toughness decreased with increasing bedding plane inclination angle. The larger the specimen size was, the smaller the nominal strength and the larger the apparent fracture toughness was. When the bedding inclination angle increased from 0° to 90°, the effective fracture energy and the effective FPZ size both first decreased and then increased within two complex variation stages that were bounded by the 45° bedding angle. Regardless of the inherent anisotropy of geomaterials, the nominal strength and apparent fracture toughness can be predicted by the energy-based size effect law, which demonstrates that geomaterials have obvious quasi-brittle characteristics. Theoretical analysis indicated that the true fracture toughness and energy dissipation can be calculated by linear elastic fracture mechanics only when the brittleness number is higher than 10; otherwise, size effect tests should be adopted to determine the fracture parameters.