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At Rest Earth Pressure Coefficients

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geomane

Geotechnical
Apr 4, 2013
199
How can I figure out the At Rest Earth Pressure Coefficient (Kₒ) From the following info:

Earth Pressure
Depth(ft) Unit Weight (pcf) friction Coefficients(Rankine)
From To Soil Type Moist Submerged angle(Φ) Active Passive AtRest
0 7 SP, SP-SM 105 42.6 29 0.347 2.88 ?
7 25 SP, SP-SM 110 47.6 30 0.333 3 ?
25 40 SP, SP-SM 120 57.6 33 0.295 3.39 ?

Is there a way other than the formula: Kₒ = 1-sin(Φ)

Can you figure it out from the soil unit weight? Basically, I need to figure out the at rest coefficients from info on a boring log only.

Also, I need it to figure out the Equivalent Fluid Pressure EFP:
EFP = [Effective stress X (Kₒ)] + 62.4



 
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I am not aware of any other formula to find the at-rest pressure coefficient than the formula you provided. No, you can't figure it out based on the soil unit weight.

I am assuming the boring log does not contain SPT blow counts, if it did you could correlate that to a friction angle.
 
You won't be off by too much just taking the Rankine Ka and multiplying it by 1.5.

I'm a bit unclear of the exercize though. At rest earth pressure is acting against some wall that is supported at the top from rotation. Where's the wall?

f-d

¡papá gordo ain’t no madre flaca!
 
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