Winkler load-transfer analysis for laterally loaded piles

The Winkler modulus for a vertical beam buried in elastic soil is reassessed for the problem of a horizontal loaded pile in the framework of linear elasticity. By matching the integral solution in elastic continuum and the expression with the elastic Winkler modulus, the subgrade modulus of an infinitely long pile embedded into elastic space is obtained first. Then the influence of embedment depth and pile rigidity on the subgrade modulus is evaluated by virtue of Mindlin's and Kelvin's solutions, which gives the variation of the Winkler spring stiffness along the pile length. Comparison of the results by the present method for single piles in homogeneous and nonhomogeneous soils has shown good agreement with those obtained from the more rigorous elastic continuum solutions and boundary element method, which also revealed the disadvantage of the conventional Winkler expression in evaluating the displacement of the pile. Finally, the present method is used to analyze the pile-soil-pile interaction of a pile group, which also shows good agreement with the finite element method and the elastic continuum method, and proves the feasibility of extending the active subgrade modulus into the realm of the horizontal loaded pile group.