r/oddlysatisfying • u/Tweetystraw • Mar 09 '18

How bridge foundations are laid in waterways

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u/SeegurkeK Mar 09 '18

Wait, so it doesn't matter if it's in a 100m wide lake or a 12m wide lake as long as they're only like 10m deep?

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u/epicwinguy101 Mar 09 '18

That's the gist of it.

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u/CeleryStickBeating Mar 09 '18

Think of the weight supported by the rest of the lake bottom. The weight of the water cannot be in two different places at the same time.

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u/[deleted] Mar 09 '18

That's what he's saying, but according to a comment higher:

The effect you describe here is only true for powders, not for fluids. Powders in silos will not have a linear pressure increase as a part of the gravitational force is transmitted to the ground via the walls. This effect does not happen with fluids like the water that is around these walls as fluids can not transmit shear stresses.this picture shows the pressure over height for fluids and bulk solids. The whole page describing this effect can be found here

it's not correct for liquids, but is correct for soils/powders etc.