Quote:
Originally Posted by island911
Yep, but...
Pretty much this ^ but that should read: so less pressure force on the wall.
IOW, the bottom of the dam is seeing the highest pressure (force per area) so by minimizing the area down there (with a V rather than U) the force is minimized.
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Beat me too it. Also, the toe of the dam has to be the thickest (in an upstream/downstream direction). If the toe is the point of a V, a whole lot less concrete (or other material) has to poured than if its a U.
But I think the original thought was not so much about the shape of the dam, but the hole behind it. The hole doesn't have to mimic the shape of the dam. The limiting factor is simply, as was calculated by others, the immense amount of earth that must be moved. Dam sites are chosen to take advantage of a large naturally occurring hole (canyon or valley), that needs the smallest possible plug (dam) to become a reservoir.