Geotecnical behavior of pile during soil consolidation

Piles driven into soft clay are often subjected to Downdrag force. Thedowndrag force develops negative skin friction on the pile shaft. Negative skinfriction is the most common problem in the design and construction of pilefoundations in soft soil. Depending on the relative movement of the pile soilsystem, positive and negative skin friction developed on pile shaft.This research investigates the behavior of pile during soil consolidation.Experimental work was developed to analyze the negative skin friction on asingle pile embedded in clay. The clay layer was allowed to consolidate underthe effect of surcharge loading.The investigation depicts that monitored strains along the pile lengthreflect the consolidation process with time. Strain increases from the pile topuntil it reaches a peak value at the location of the neutral plane. Shear stress, asa function to the axial strain, is initiated from zero value at the surface of the soiland increases until it reaches a peak negative value at an intermediate depth.Then, it decreases down to zero at the elevation of the neutral plane, where thepositive skin friction develops. The neutral plane is located toward the end ofthe pile as the base layer getting stiffer. Closed form equations of Shong, 2002,can predict the experimental results in very well agreement. I