New Load Transfer Hyperbolic Model for Pile-Soil Interface and Negative Skin Friction on Single Piles Embedded in Soft Soils

A proper load transfer model describing the pile and surrounding soil interaction is important for accurately predicting the behavior of piles. In this paper, a new load transfer hyperbolic model for the pile-soil interface is developed based on soil-structure interface tests reported in the literature, which consider the characteristics of increasing initial shear stiffness, the development of shear strength at the pile-soil interface, the loading, step by step loading, unloading, and reverse loading shearing behavior of the pile-soil interface with consolidation. The proposed model was validated by the close agreement between the computed results and published case histories. Further studies based on the proposed model considering negative skin friction on single piles under pile head load and/or surcharge were subsequently conducted. It was found that the pile-soil interface undergoes complicated shearing, and the depth of the neutral plane (NP) and the skin friction along the pile shaft vary during consolidation. The magnitude of the pile head load and pile installation time has a significant impact on the depth of the NP and the dragload. Pile capacity was shown to decrease with consolidation. © 2014 American Society of Civil Engineers.