Tectonic and gravity extensional collapses in overpressured cohesive and frictional wedges
Tectonic and gravity extensional collapses in overpressured cohesive and frictional wedges
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超压粘性楔和摩擦楔中的构造和重力伸展塌陷
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
B. Maillot
中科院分区：
文献类型：
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作者：
X. Yuan;Y. Leroy;B. Maillot
本文用解析方法研究了在任意地形、有限范围和倾斜的弱沉降体上的粘性和摩擦楔形体中的两种伸展坍塌模式。第一种模式是由半地堑的作用引起的重力塌陷，它扎根于沉降块上，并将楔形体的前部推向大海。第二种模式是由于后壁的构造伸展，具有类似的半地堑运动学和楔形体后部的向陆滑动。预测的最大强度定理，相当于运动学方法的极限分析和这两个崩溃机制的基础上，不仅完全匹配的解决方案的临界库仑楔理论，一旦适当的修正，但概括他们在几个方面：楔的有限大小，组成的粘性材料和任意地形。这一概括有利于我们对许多实验室实验和现场案例的理解。例如，根据实验验证的分析结果，一个内聚的三角形楔形体的稳定性转变发生在最大长度的分离单元的激活时。它表明，地形的细节，特别是梅希隆半岛（智利北部）的例子是，然而，负责选择一个短的长度尺度，动力不稳定性对应的锋面重力不稳定性。合理的内聚量足以使文献中提出的压力对应于稳定性转变，而不是动态不稳定状态。
Two modes of extensional collapse in a cohesive and frictional wedge of arbitrary topography, finite extent, and resting on an inclined weak d é collement are examined by analytical means. The first mode consists of the gravitational collapse by the action of a half‐graben, rooting on the d é collement and pushing seaward the frontal part of the wedge. The second mode results from the tectonics extension at the back wall with a similar half‐graben kinematics and the landward sliding of the rear part of the wedge. The predictions of the maximum strength theorem, equivalent to the kinematic approach of limit analysis and based on these two collapse mechanisms, not only match exactly the solutions of the critical Coulomb wedge theory, once properly amended, but generalizes them in several aspects: wedge of finite size, composed of cohesive material and of arbitrary topography. This generalization is advantageous to progress in our understanding of many laboratory experiments and field cases. For example, it is claimed from analytical results validated by experiments that the stability transition for a cohesive, triangular wedge occurs with the activation of the maximum length of the d é collement. It is shown that the details of the topography, for the particular example of the Mejillones peninsula (North Chile) is, however, responsible for the selection of a short length‐scale, dynamic instability corresponding to a frontal gravitational instability. A reasonable amount of cohesion is sufficient for the pressures proposed in the literature to correspond to a stability transition and not with a dynamically unstable state.