THEORY OF CHOCOLATE TABLET BOUDINAGE
THEORY OF CHOCOLATE TABLET BOUDINAGE
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DOI：
10.1016/0191-8141(88)90022-3
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发表时间：
1988-01-01
影响因子：
3.1
通讯作者：
GHOSH, SK
中科院分区：
文献类型：
--
作者：
GHOSH, SK
二维石香肠是一种扁平型的整体变形，在各个方向上具有相等的层平行延伸，导致石香肠在平面视图中的圆形或多边形轮廓的发展。实验和理论研究表明，具有两组相互垂直的石香肠轴的巧克力石香肠可能以不同的方式形成。(1)在基质中不均匀的平行于层的伸展导致一组伸展裂缝形成垂直于基质中的最大主应力。一旦这些狭长的石香肠形成，脆性层中的最大主应力变得近似平行于石香肠的长轴。结果，第二组裂缝垂直于第一组形成。(2)在线理岩石中，抗拉强度的各向异性导致两组伸展裂缝相继形成，平行于线理和垂直于线理。取决于线理的方向，石香肠轴可能平行于或不平行于基质中的主应力。(3)当两个连续的单向石香肠相互叠加时，也可能形成平面呈矩形的石香肠。无论基质中的主拉伸应变速率的方向如何，第二代拉伸裂缝都可能近似垂直于第一代石香肠轴形成。
Two-dimensional boudinage in a flattening type of bulk deformation, with equal layer-parallel extensions in all directions, leads to the development of roundish or polygonal outlines of boudins in plan-view. As combined experimental and theoretical studies show, chocolate tablet boudinage with two sets of mutually perpendicular boudin axes may form in different ways. (1) Unequal layer-parallel extension in the matrix results in one set of extension fractures forming perpendicular to the greatest principal stress in the matrix. Once these long narrow boudins are formed, the greatest principal stress in the brittle layer becomes approximately parallel to the long axis of the boudin. As a result a second set of fractures forms normal to the first set. (2) In lineated rocks the anisotropy of tensile strength leads to the sequential formation of two sets of extension fractures, parallel and perpendicular to the lineation. Depending on the orientation of the lineation the boudin axes may or may not be parallel to the principal stresses in the matrix. (3) Boudins with rectangular plan-view may also form when two successive events of unidirectional boudinage are superposed on one another. Irrespective of the direction of principal extensional strain rate in the matrix, the second generation extension fractures are likely to form approximately perpendicular to the first generation boudin axes.