Dear Colleagues, someone can recommend me a book or a paper where I can find something about the geotechnical design of ballast and subgrade for railroads.
There was a lot of work on this out of Queens University in Ontario. The guy's name escapes me at present but he was pretty famous. I will try to look around and find out. Sorry I can't be of more direct help at this time.
An excellent book for this topic is "Track Geotechnology and Substructure Management" by Ernest Selig and John Waters. It is published by Thomas Telford. You could probably get a copy through Amazon. Good Luck.
If interested in ballast strength, a good (and recent) source is Indraratna et al. (1998) "Shear behavior of railway ballast based on large-scale triaxial tests" ASCE JGGE 124(5).