Studying the Effects of Pile Load on Negative Skin Friction in Basrah Governorate

The seriousness of the phenomenon of negative skin friction on piles penetrating Basrah soil in Iraq is investigated via the finite element method. The most common (0.285×0.285 m) precast driven and (0.8 m diameter) bored piles, are analyzed under the structural loads and down drag forces due to recent fill. A two-dimensional program adopting nonlinear constitutive relations for soil layers is utilized. The results revealed a great decrease in negative skin stress and pile length on which the phenomenon is to act upon, due to the application of structural loads. Reductions in drag forces as much as (86%) for driven piles and (96%) for bored piles are recorded in some sites. It is also concluded that, overlooking the negative skin friction does not result in failure and that more economical pile capacities could be adopted.