New insights into the development of brittle shear fractures from a 3-D numerical model of microcrack interaction
New insights into the development of brittle shear fractures from a 3-D numerical model of microcrack interaction
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DOI：
10.1016/j.epsl.2006.06.041
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发表时间：
2006-09
影响因子：
5.3
通讯作者：
D. Healy;Richard R. Jones;R. Holdsworth
中科院分区：
文献类型：
--
作者：
D. Healy;Richard R. Jones;R. Holdsworth
现有的脆性剪切破坏模型无法解释涉及多模态断裂组发展的三维变形。在对同期四模断层和变形带阵列的现场观测的启发下，我们使用了一个理想的微观力学模型来解释脆性剪切裂缝是如何形成向所有三个远程主应力倾斜的。在线性各向同性弹性矩阵中，我们将拉伸微裂纹建模为有限的椭球状空洞，受到小的开口应变。孤立微裂纹末端周围的拉应力叶的几何形状促进了邻近裂纹相对于规定裂纹方向的雁行相互作用。这些相互作用的裂纹阵列合并成一个贯通的复合断裂面，导致脆性剪切破坏面斜向所有三个坐标轴和所有三个远程主应力。实验证据支持复合剪切断裂可以通过许多组成的拉伸微裂纹合并在平面内扩展的观点。该模型基于I型裂纹周围弹性应力场的三维几何形状，可以解释在三轴压应力场中形成的多模态断层的斜向。
Existing models of brittle shear failure are unable to account for three-dimensional deformation involving the development of polymodal sets of fractures. Motivated by field observations of contemporaneous arrays of quadrimodal faults and deformation bands, we use an idealised micromechanical model to explain how brittle shear fractures can form oblique to all three remote principal stresses. We model tensile microcracks as finite ellipsoidal voids, subjected to small opening strains, in a linear isotropic elastic matrix. The geometry of the tensile stress lobes around the ends of an isolated microcrack promotes the en echelon interaction of neighbouring cracks with respect to the prescribed crack orientation. Coalescence of these interacting crack arrays into a through-going composite fracture surface leads to a brittle shear failure plane oriented obliquely to all three coordinate axes and all three remote principal stresses. Experimental evidence supports the idea that composite shear fractures can propagate in-plane through the coalescence of many constituent tensile microcracks. Our new model, based on the 3-D geometry of the elastic stress field around a mode I crack, can explain the oblique orientations of polymodal faults formed in a triaxially compressive stress field.