| 摘要 |
A revetment (10) made wholly or predominantly from concrete, useful to line a stream bed, having upper and lower surfaces (20, 30), and having upstream an d downstream edges (50, 40), has, for each upstream edge, an upstream bevel (60), which intersects the upper surface and which intersects said upstream edge. The revetment has an array of holes (70) extending between the upper a nd lower surfaces. Each hole has a lateral wall (74) flaring outwardly in a downstream direction from a circular mouth (72) at the lower wall to an elongate mouth (76) at the upper wall. Each upstream or downstream edge is stepped so as to define an upper or lower flange (42, 52). In an assembly of such revetments, which may be connected to one another, as by cables (14), each of at least some of the upper flanges overlies one of the lower flanges .
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