The Influence of Negative Skin Friction on Piles and Pile Groups & Settlement of existing Structures

Negative skin friction occurs when concrete piles are situated in soft soils, consolidating soilmass, etc., resulting in a downward force that increases loading on shaft piles and reduces the bearing capacity of the piles. A new concept based on the shifting rate of piles, and the settlement rate of the surrounding soils has been suggested far the study of negative skin friction. Negative skin friction occurs when the settlement rate of the surrounding soils is greater than that of the piles. Some relative equations have been established to define the negative friction zone of piles. Negative skin friction is dependent on the time factor and the degree of consolidation of the soil mass and can be negligible when the soil mass is nearly completely consolidated. The calculation of negative skin friction of some specific concrete piled foundations is also presented to be compared with other methods. The use of a concrete slab combined with beams and piles was employed to treat negative skin friction on concrete piles in soft subsoil.