Frost protected Shallow foundation design for existing bridge foundation

[asp1230]

I am working on a project where embedment depth for existing bridge foundation will be reduced. This is third such bridge that we have seen in the recent past. Anybody has any experience with protecting the footing subgrade from frost? Thanks.

 

[oldestguy]

Sounds like not at a stream where scour is involved.

For houses, etc, we regularly recommend insulating the ground to prevent heaving underneath shallow foundations and/or slabs. We used closed cell Styrofoam sheets. You can get many different thicknesses and those that are suitable for under freezers. Assuming the bearing pressure will not exceed the compressive resistance of the foam it will work. In addition we extend the insulation out from the foundation 4 feet in all directions at a burial depth below the probable depth of excavation for outside plantings, etc. Don't forget the column and other supports will conduct the heat out of the ground and cause some problem there.

Using this idea, this may help with some protection of the soil below from freezing. A common thickness used is 1.5" in Wisconsin.

 

[asp1230]

@oldestguy: Thanks.