Curved Strain Wedge Analysis of Laterally Loaded Flexible Piles in Various Soil Types

Abstract

This paper establishes an approximate circular cone strain wedge model and proposes an analytical method that can effectively connect practice with theory for the behavior of laterally loaded flexible piles with both free-head and fixed-head conditions in various types of soil based on the real shape of the strain wedge. The analytical method of the curved strain wedge model, in which the Duncan-Chang model is used to describe the stress-strain relationship of the soil and the relationship between the shear strain γ and the horizontal strain ε is improved on the basis of the Mohr circle of strain, is applicable to clay and sand as well as c-φ soil. A method of calculating the shear stress along the pile is proposed for circular piles according to the friction direction between the pile and the surrounding soil. The modulus of the soil foundation reaction is calculated along the whole pile length based on the finite-difference method, without calculating the height of the strain wedge, which can truly reflect the nonlinear deformation characteristics of the pile foundation under lateral loading. The proposed method is verified by six case studies, including five field measurement experiments for various types of soil and one finite-element analysis. Comparisons show that the agreement between the results from the curved strain wedge method and those from the field tests and the finite element analysis is generally satisfactory.