Limit on Passive Pressure
Limit on Passive Pressure
(OP)
I often see geotechnical reports that recommend upper limits on passive pressure, and I cannot find a good reason for this limit in the literature. It is often in relation to soldier pile walls where an equivalent passive fluid pressure is provided, for example; "allowable passive pressure of 250 psf per foot of depth up to a maximum of 4,000 psf". Any ideas on where this maximum limit comes from? Theoretically, I think the passive pressure should keep increasing with depth.





RE: Limit on Passive Pressure
Mike Lambert
RE: Limit on Passive Pressure
RE: Limit on Passive Pressure
www.PeirceEngineering.com
RE: Limit on Passive Pressure
RE: Limit on Passive Pressure
www.PeirceEngineering.com
RE: Limit on Passive Pressure
RE: Limit on Passive Pressure
I've also heard people say they cap the pressure due to the amount of movement that is required to mobilize the full pressure. Don't know that I really agree with that, but I have heard it.
I'm not sure most structural engineers understand how much movement can be required to mobilize full passive pressure and most geotechnical reports that I've seen do not do a good job of discussing the subject.
Mike Lambert
RE: Limit on Passive Pressure
http://www.soilstructure.com/
RE: Limit on Passive Pressure
Many recommendation are simplistic and conservative due to the nature of geotechnical engineering and the minimal amount of knowledge of specific soil conditions, strengths, etc all obtained from a very limited scope of work that is all the owner is willing to pay for. All the reasons stated above make sense to me and if one is expecting to rely on large amounts of passive resistance, they may want to look at their specific methods and the quality of the soil information obtained before relying a simple calculated value with no limits. In other words, I don't really have a problem with it being expressed that way as a general report recommendation.
RE: Limit on Passive Pressure
RE: Limit on Passive Pressure
then again. . .
f-d
ípapß gordo ainÆt no madre flaca!
RE: Limit on Passive Pressure
RE: Limit on Passive Pressure
RE: Limit on Passive Pressure
I have seen folks design earth pressures on retaining walls using K-naught on both sides. Now I know that is not the OP question, just another variation on folks and their engineering approaches. For the case of K-naught, the engineer just didn't want the retaining wall to move at all!
f-d
ípapß gordo ainÆt no madre flaca!