design guide for lateral pressures to use for Geofoam

[HouseBoy]

I am considering the use of Geofoam (EPS rigid foam blocks), placed directly against a residential basement wall as a way to significantly reduce the lateral soil pressure.
Can anyone refer me to a good reference for the proper provisions I will need to use?
Most critically, I'm wondering what "equivalent fluid pressure" I could/should use for design along with what kind of proportions (thickness and/or steps) that might be required
Are there design guides available for this that someone can link me to?

Short of an actual link or publication, what pressures and proportions do others find appropriate for design?

Thanks

 

[fattdad]

Won't the earth pressure push on the geofoam blocks and the blocks transfer the native soil earth pressures to your basement?

I'd look closely at things that seem too good to be true. . .

f-d

¡papá gordo ain’t no madre flaca!

 

[GeofoamSpecialist]

If you place the geofoam above the plane of failure of the native soils you will end up with a zero net lateral load factor on the wall.

Nico Sutmoller
Geofoam Specialist
geofoam@insulfoam.com

http://www.insulfoam.com

 

[fattdad]

Interesting, but not convincing. I'm not saying it isn't true, I'm just saying there is earth pressure acting on the geofoam and the geofoam in turn seems like it'd transfer the load to the wall. Balance must be preserved, eh?

f-d

¡papá gordo ain’t no madre flaca!

 

[VAD]

I agree with Geofoam Specialist. Geofoam can be mnufactured to have a certain amount of compression. His concept is what is generally used when one replaces the Rankine wedge with graular material. the lateral earth pressures are considerd to be provided by the granular material and hence less. Sometimes we need to discuss products etc with the manufacturers. In the same vien we need also to discuss construction techniques with Contractors. These are abut a few examples of the general failure of geotechnical engineers and reason why designs are thrown in the garbage. Not saying that geotechnical Engineers do not have sound ideas, but many are textbook huggers

 

[PEinc]

I agree with VAD and GeofoamSpecialist. Where I have seen geofoam used (usually behind a new abutment), it followed the slope of the soil wedge so that there was no earth pressure on the abutment.

http://www.PeirceEngineering.com

 

[fattdad]

I don't want to say I disagree. I just want to learn. How does it work? If we take clay out of the active Rankine wedge and replace it with gravel, we'll decrease the wall pressure, but not render it zero.

So, I guess if we take a stable slope (let's say 1:1 and build a vertical wall at the base of the slope there will be no earth pressure as there'll be air on both sides of the wall. I guess the foam is replacing the air and because the slope is stable the wall pressures would be trivial.

Maybe I just needed to think on this a little more. . .

Sorry if I confused matters. I just don't have any experience in this at all.

f-d

¡papá gordo ain’t no madre flaca!