Improved hyperbolic model of load-transfer for pile-soil interface and its application in study of negative friction of single piles considering time effect

An improved hyperbolic model of load-transfer for the pile-soil interface was developed.It considered the increase of the initial shear stiffness of the surrounding soil with consolidation and unloading and cyclic behaviour of the interface.The negative skin friction of single pile under different pile head loads was also studied.It was shown that the position of neutral point of pile shaft varied with the consolidation of surrounding soil and the magnitude of pile-head load.The drag force would be reduced when the piles were installed after the soil had reached a certain degree of consolidation.