SOIL BEARING FOOTING PRESSURES

[cap4000]

Can someone explain why the difference between these two methods. The first one is the typical 2V:1H with the Boussinesq pressure isobars. Between them there seems to be large pressure differences for both Spread and Continuous Footings.

 

[Focht3]

What are you doing with them?



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[cap4000]

In response to the Focht3 question. I am trying to figure lateral pressures from spread and column footings against existing foundation walls at varying depths.

 

[Focht3]

Then use Boussinesq or Westergaard - the 2:1 distribution is for estimating vertical pressures only. Poulos and Davis' book includes solved equations, as well as charts, for evaluating the lateral pressures.

By the way, were the pressures you calculated using the 2:1 approach about twice as high as those from Boussinesq?



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[BigH]

Poulos and Davis is a great reference (Elastic Solutions for Soil and Rock) and should be in everyone's library. Newmark has a lateral load chart you can use. I'll have to confirm, but for surcharge loadings on non-yielding walls (footing near the wall but founded "high up&quot which you might have, the lateral pressures are, I believe, to be doubled. I'll try to confirm this.