Kun Ferenc, Pál Gergő, Varga Imre, Main Ian G
Department of Theoretical Physics, University of Debrecen, PO Box 5, 4010 Debrecen, Hungary
Institute for Nuclear Research, Hungarian Academy of Sciences (Atomki), PO Box 51, 4001 Debrecen, Hungary.
Philos Trans A Math Phys Eng Sci. 2018 Nov 26;377(2136):20170393. doi: 10.1098/rsta.2017.0393.
Faults and damage zone properties control a range of important phenomena, from the hydraulic properties of underground reservoirs to the physics of earthquakes on a larger scale. Here, we investigate the effect of disorder of porous rocks on the spatial structure of damage emerging under compression. Model rock samples are numerically generated by sedimenting particles where the amount of disorder is controlled by the particle size distribution. To obtain damage bands with a sufficiently large length along axis, we performed simulations of 'Brazilian'-type compression tests of cylindrical samples. As failure is approached, damage localization leads to the formation of two conjugate shear bands. The orientation angle of bands to the loading direction increases with disorder, implying a decrease in the internal coefficient of friction. The width of the damage band scales as a power law of the degree of disorder. Inside the damage band, the sample is crushed into a large number of pieces with a power law mass distribution. The shape of fragments undergoes a crossover at a disorder-dependent size from the isotropy of small pieces to the anisotropic flattened form of the large ones. The results provide important constraints in understanding the role of disorder in geological fractures.This article is part of the theme issue 'Statistical physics of fracture and earthquakes'.
断层和损伤带性质控制着一系列重要现象，从地下储层的水力性质到更大尺度上的地震物理学。在此，我们研究多孔岩石的无序性对压缩作用下产生的损伤空间结构的影响。通过沉积颗粒在数值上生成模型岩石样本，其中无序程度由颗粒尺寸分布控制。为了获得沿轴具有足够大长度的损伤带，我们对圆柱形样本进行了“巴西”式压缩试验模拟。随着接近破坏，损伤局部化导致形成两个共轭剪切带。带与加载方向的取向角随无序程度增加，这意味着内摩擦系数减小。损伤带的宽度按无序程度的幂律缩放。在损伤带内部，样本被压碎成大量具有幂律质量分布的碎片。碎片形状在与无序相关的尺寸处发生转变，从小碎片的各向同性到大碎片的各向异性扁平形式。这些结果为理解无序在地质断裂中的作用提供了重要限制。本文是“断裂与地震的统计物理学”主题特刊的一部分。
