Mat Foundations - Conceptual Q

[Martino8]

We're working on a project with very poor soils and may have to deal with higher than normal differential settlements. As a mitigating solution, the Geotechnical engineer is looking at the potential for a mat foundation.

We understand conceptually how a rigidly interconnected system will be able to help span across areas with a loss of support(ie differential settlement). The question becomes, how do we analyze it? I could see building a finite element model with the soil support being represented by area springs and the differential support effects being achieved by introduction variations in the springs. We're also aware of the old prescriptive method for dealing with expansive soils that was originally developed by WRI. Anybody know of any good design references on the matter?

 

[GC_Hopi]

ACI 336 is the working committee for Footing, Mats and Drilled Piers. Take a look at their documents. Also the geotech should help direct you on how to model the foundation. You may have to do some model iterations with the geotech providing input. Also if the soil is very poor then you could look at deep foundation, geopiers, or good old fashion soil replacement(a rock mat could be used if you have high and distributed loading).