Compensated Foundations for Bridges 1

[bailey]

Is there anyone out there with experience using Expanded Polystyrene (EPS or commonly known as styrofoam)as the "filler" in compensated foundations.

I am considering using EPS beneath a bridge foundation in a location where the soil conditions are very poor. Soil borings taken indicate clayey strata and N = weight of rod at 100 ft. The plan is to form 2 closed sheetpile cells (one for each abutment), excavate 1/2 of the wgt of the proposed bridge witin eash cell (superstructure + substructure), fill the cell with EPS, and construct the bridge on top of the EPS. We have found that our footings have to be quite large to minimize the bearing pressure on the EPS (2000 psf is the maximum allowable we could find).

Any advise or comments are appreciated.

Bailey

 

[georam]

I believe you are talking about geofoam. However, I never use it for application beneath a bridge foundation. Geofoam is usually used as insulation , reinforced retaining wall or lightweight fill in slope embankments which require little net increase of loads.
You should consider to read the following articles in the internet :
1. A paper in Electronic journal of geotech. engrg by Dr. Horvath.

http://geotech.civen.okstate.edu/ejge/Ppr9605/index.htm

There are some description about past,present and future use fo geofoam. Brief discussion is also made about the usage of geofoam as structural member.
There is also an internet site dedicated to geofoam,

http://www.geofoam.org/

2. Some information about construction of highway in Utah,presented by Steven Bartlett of Utah DOT. Some nice photos and description of the usage of geofoam/EPS.

http://geofoam.syr.edu/i15_cs.html

Also check the Geofoam Research Center (GRC) at Syracuse University. Their website is

http://geofoam.syr.edu/about_ls.html

Hope this helps

 

[bailey]

Georam:

Thank you for the help. I think I'll call the GRC @ Syracuse University and see what they think.

 

[ishvaaag]

I understand lighweight fills are used sometimes to obtain balanced foundations. This is OK IF

the total structure outfit that is related to the lightweight infill it is itself rigid and stable enough as to not develop any problems from the proximity of the lighweight infill.

The preferable situation for compressible infills should be outside the plan of the main construction.

In some cases it can be useful the infill be partly under or inside what built. It can be used as temporary support for further construction, but the whole thing must be stiff enough and not rely later on this part as fundation. Rigid vessel action should be sought.

In short, my view of balanced foundation things, you build a vessel, but never rely for support in the soft part. If the soft infill supportis any load other than transitory for consturction, they must be pontooned by loose slabs.

Also, polyestirene is edible by rats, and as any plastic, creeps. Judge what if.