Fracture coalescence in rock-type materials under uniaxial and biaxial compression
Fracture coalescence in rock-type materials under uniaxial and biaxial compression
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DOI：
10.1016/s0148-9062(98)00005-9
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发表时间：
1998-10-01
影响因子：
7.2
通讯作者：
Einstein, HH
中科院分区：
文献类型：
--
作者：
Bobet, A;Einstein, HH
通过对石膏？，在单轴和双轴压缩中用作岩石模型材料。几种新现象及其依存关系？观察几何形状和其它条件。样本有两个预先存在的裂缝或缺陷，它们以不同的几何形状排列，并且可以是开放的或闭合的。两个不同的测试系列进行这些缺陷的几何形状，一个单轴加载和一个双轴加载，其中施加的围压为2.5，5.0，7.5和10 MPa。随着垂直（轴向）载荷的增加，新的裂纹从缺陷中产生并最终合并。观察到裂纹滑移、翼裂纹萌生、二次裂纹萌生、裂纹合并和失效。出现两种类型的裂纹：翼形裂纹是拉伸裂纹，而二次裂纹是在与裂纹大致共面的平面内作为剪切裂纹产生的。二次裂纹通常在同一平面内以剪切裂纹形式扩展，但根据几何形状，它们也以拉伸裂纹或剪切裂纹形式扩展到平面外。在单轴或低约束双轴条件下，翼裂纹起始于裂纹尖端，但在较高的约束应力下，翼裂纹向裂纹中部移动并完全消失。三种类型的聚结，这取决于几何形状的缺陷，并在一定程度上对应力条件，发生，他们，汽车？可以通过翼裂纹和二次裂纹的不同组合来区分。对于闭合缺陷试样，在透镜处;在裂纹开始之前，要求缺陷部分脱粘和滑移。在单轴压缩中，聚结和破坏同时发生，而在双轴压缩中，破坏发生在聚结之后。(C)1998年由Elsevier Science Ltd.出版，版权所有。
Fracture coalescence, which plays an important role in the behavior of brittle materials, is investigated by loading pre-fractured specimens of gypsum?, used as a rock model material, in uniaxial and biaxial compression. Several new phenomena and their dependence or? geometry and other conditions are observed. The specimens have two pre-existing fractures or flaws that are arranged in different geometries, and that carl be either open ol closed. Two different test series are performed with these flaw geometries, one under uniaxial loading and one with biaxial loading in which confining stresses of 2.5, 5.0, 7.5 and 10 MPa are applied. As the vertical (axial) load is increased, new cracks emanate from the flaws and eventually coalesce. Flaw slippage, wing crack initiation, secondary: crack initiation, crack coalescence, and failure are observed. Two types of cracks occur: wing cracks, which are tensile cracks, and secondary cracks which initiate as shear cracks in a plane roughly co-planar with the flaw. The secondary cracks usually propagate as shear cracks in the same plane hut, depending on the geometry, they also propagate out of plane as either tensile ol shear cracks. The wing clacks initiate at the flaw tips for uniaxial or low confinement biaxial conditions bur move to the middle of the flaw and disappear completely for higher confining stresses. Thr ec types of coalescence, which depend on the geometry of the flaws and to some extent on stress conditions, occur, they, car? be distinguished by different combinations of wing cracks and secondary cracks. For closed flaw specimens, at lens; partial debonding and slippage of the flaws is required prior to initiation of a crack. In uniaxial compression coalescence and failure occur simultaneously,, while failure in biaxial compression occurs after coalescence. (C) 1998. Published by Elsevier Science Ltd. All rights reserved.