Analytical method for estimation of negative skin friction on foundation surface in collapsible loess soil

Pile foundations on structurally weak easily compressible clayey soils or collapsible sandy loess soil are required to be footed through this collapsible soil layer deeper in non-collapsible soil below. In such conditions negative skin friction on a pile surface in contact with collapsible soil layer can be caused due to increased load pressure, soil wetting and thawing processes resulting in additional settlement in foundation. Briefly, the negative skin friction can be described as downward drag force exerted on a pile surface. This part presents the new analytical method for determining the negative skin friction on the surface of the pile.