Criterion Delineating the Mode of Headcut Migration
Criterion Delineating the Mode of Headcut Migration
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DOI：
10.1061/(asce)0733-9429(1993)119:1(37
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发表时间：
1993
影响因子：
2.4
通讯作者：
O. Stein;P. Julien
中科院分区：
文献类型：
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作者：
O. Stein;P. Julien
通常认为有两种顶切迁移模式：（1）旋转顶切，在迁移时趋于变平;（2）阶梯式顶切，趋于保持几乎垂直的面。一个数学描述的沉积物剥离潜力的上游和下游的头切是用来描绘这些模式的迁移。划定参数是从上方侵蚀开挖面所需时间与从下方破坏开挖面所需时间的比率。这种侵蚀时间尺度比是水流、泥沙和几何参数的无量纲函数。对于均质粘性土的极限情况，时间尺度比是弗劳德数和跌落高度与正常流深的纵横比的简单函数。这种关系是校准使用原始的实验室实验的头切迁移在最初的垂直头切，并验证了独立的现场实验头切传播在四个不同的均质粘性土壤。
Two modes of headcut migration are generally recognized: (1) rotating headcuts that tend to flatten as they migrate; and (2) stepped headcuts that tend to retain nearly vertical faces. A mathematical description of the sediment detachment potential immediately upstream and downstream of the headcut is used to delineate these modes of migration. The delineating parameter is the ratio of the time required to erode the headcut face from above to the time required to undermine the headcut face from below. This erosional time-scale ratio is a dimensionless function of flow, sediment, and geometry parameters. For the limiting case of homogeneous cohesive soils, the time-scale ratio is a simple function of a Froude number and the aspect ratio of drop height to normal flow depth. This relationship is calibrated using original laboratory experiments of headcut migration in initially vertical headcuts and verified by independent field experiments of headcuts propagating in four different homogeneous cohesive soils.