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Active and passive soil pressure

Active and passive soil pressure

Active and passive soil pressure

(OP)
Hi all
We had a discussion at the office today regarding active and passive soil pressure. Does anybody know why it is called "active" and "passive"?
I have to admit that I never really thought about it. But now I can't stop wondering smile, and Google only explains what it is. At least that is all I have found.

Regards

Thomas

RE: Active and passive soil pressure

I have always thought of it like this. Active requires the wall to move in order to generate the pressure (the wall is actively moving). Passive pressure imposes load on the soil BECAUSE the wall moved (it is a passive reaction).

RE: Active and passive soil pressure

This is for the geotechs who will and should correct me but as a non-soils guy maybe my explanation will have the value of a layman's explanation, which can sometimes be easier to understand if not necessarily fully correct.

Active pressure is the soil actively pushing against the wall as the soil wedge tries to slide away from itself.

Passive pressure is the wall pushing against the passive soil in front of it, i.e., plowing through undisturbed, otherwise passive, soil.

That's why passive pressure is usually more than the active pressure. It's the difference between trying to hold back an avalanche or pushing over a mountain...on a much smaller scale.

RE: Active and passive soil pressure

The "active" pressure is an applied force, a force "acting" on the wall. The "passive" pressure is an available resisting force that can prevent the wall from overturning and sliding. The "passive" pressure is not an applied force. It is just there "passively" to resist the applied active loads. Passive pressure cannot push a wall backwards.

www.PeirceEngineering.com

RE: Active and passive soil pressure

(OP)
Hi again
Interesting comments.
The reason the discussion started was this. When you move a wall towards the soil and "activate" the soil, the pressure is called "passive". One of my collegues thought that active pressure was when the wall moved towards the soil.

I just know what it is but have never before thought about the origin for the expressions. Perheps the origin for the terms is Germany or France smile.

So far I think i like PEinc explanation best smile.

Thomas

RE: Active and passive soil pressure

(OP)
@oklestguy
I actually did a Google search but your result was much better.

Thank you

Thomas

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