05-09-2010, 04:21 AM
on the base of my experience with Flac3D software, I think you must modify the tip interface's coupled springs. In fact, making a good estimation of interface Kn and Ks are main problems in soil-structure interaction modelling. I suggest you to firstly refer to Dr.Coduto's book , "Foundation Desgin: Principles and Practices" - Chapter 14 - page 527 , for an analytical method in uplift capacity of piles. then estimate tip bearing capacity and then modify Flac3D's kn interface property from it. Side Bearing capacity must have good estimation. On the basis of "Geotechnical Engineering" book by V.N.S.Murthy, the side capacity in uplift is equal to somewhat about (2/3) side capacity in pressure. So because of a good design of pile in pressure for side bearing capacity , I think the file must show a fairly estimation of side capacity in uplift situation.