Development of P-Y curves for single piles based on full-scale lateral load tests and the cone penetration test (CPT) in clayey soils

Abstract

It is nowadays recognized that the load-transfer P-Y curves methods offer a powerful framework of analysis of the pile response under lateral loading. The aim of this paper is to present a new formulation the P-Y curves to analyze the response of a single pile embedded in clayey soil, on the basis of the CPT test data. The methodology of work consists of analyzing 8 lateral loading tests on fully instrumented piles driven into a homogeneous saturated clayey soil. The P-Y curves were formulated by the PARECT (parabola-rectangle) function, and successful correlation of their parameters, namely the lateral reaction modulus and the lateral soil resistance, with the cone resistance as well as with the lateral pile/soil stiffness ratio was made. After a comparison with the existing P-Y curves methods, a methodology of analysis by the proposed P-Y curves for piles in normally consolidated to slightly over-consolidated clays was suggested. Moreover, a pile classification according to the pile/soil stiffness ratio was suggested, and the concept of the critical deflection corresponding to the threshold of domain of large deflections of piles was introduced. Validation process was launched by applying this methodology to a centrifuged scale model of a single bored pipe pile in a saturated slightly over consolidated clay. Direct comparison of the load-deflection curves showed an excellent prediction of the small deflections up to about 2% of the pile diameter. Beyond this value, the boundary conditions at the pile tip have an influence on the results, but showed a relatively pessimistic prediction.