Evaluation of skin friction of tapered piles in sands based on cavity expansion theory

On the basis of mechanism of tapered piles and evidence of small scale model tests, the cylindrical cavity expansion theory has been proposed to evaluate the skin friction of tapered piles by introducing stress-dilatancy relationship. Generally, either angle of internal friction or dilatancy angle was assumed to be constant to compute the skin friction. In this research this drawback has been removed and adopted both properties to evaluate the skin friction at each depth iteratively. The test result and proposed model show that a slight increase in tapering angle of the pile results in higher skin friction comparing with conventional straight piles on different types of sands at different relative densities. The parametric studies on different types of model tests, prototype tests and real type pile tests have been assessed to evaluate the skin friction and predict the proposed model. The proposed model validates the determination of skin friction using stress-dilatancy relation with reference to cavity expansion theory.