Improved Pile Geometry to Reduce Negative Skin Friction on Single Driven Pile and Pile Groups Subjected to Lateral Loads

Negative skin friction on piles represents a severe problem when piles were installed in soft clay due to consolidation process. It reduces the bearing capacity of piles by adding additional load due to drag load developed on piles. Additional settlement due to negative skin friction might produce threatening consequences such as differential settlements or cracks and can cause failure. This study investigates new techniques to construct piles either single or in groups to reduce NSF developed on the pile surface when the pile is subjected to lateral loads at its top. This study was made for both circular pile and square pile. First technique is to surround the pile by a sand socket along pile length from the ground surface till the neutral plan (NP) location. Second technique depended on changing the geometry of pile surface by adding ridges at equal spaces along pile length. Another change was made by creating equally spaced grooves on the pile surface. It was concluded that all the three techniques were effective in reducing NSF induced in the pile surface. For both circular and square piles when subjected to lateral loads NSF was reduced with ratio of (30%) in case of sand socket and ratio of (97%) for ridged and grooved piles. Also, it should be noted that the effect of lateral loads on the values of NSF has no literature.