Soil model

Question

Hello, 
 I have come across a problem where the raft foundation is resting on clayey silt. Ground water table is not encountered and soil at the site has a free swell index of 140-210 at 2.5 to 5m depth from EGL and foundation is at 3m below EGL. what kind of soil model should i chose so that it takes count of Free swell index value. And also please add if any reference for input of parameters for the condition explained.

Dennis Waterman · Answer

Dear K. 
 A swell index of 140-210 doesn't say much unless you mention what kind of swelling index it is. Is it an unloading swelling index and if so, are we talking about Cs,kappa,kappa*, Cp' or something else? Or is it a wetting swelling index, a creep swelling index...or something else? 
 For an unloading swelling index you could use any advanced model that distinguishes between primary loading and unloading/reloading, for a wetting swelling index we don't really have a standard model available, we usually model this by applying a volume strain. For creep-like swelling you could think of the swelling rock model. 
 With respect to parameters, that is something that falls outside the assistance we can provide on this forum. 
 With kind regards, 
 Dennis Waterman