A new nonlinear method for vertical settlement prediction of a single pile and pile groups in layered soils

A new and simplified nonlinear method is presented to predict the behavior of a single pile and pile groups in layered soils when placed under vertical loads. The nonlinear relationship between the shaft shear stress and the relative displacement confined to a disturbed soil zone is described by a BoxLucas1 function, and the relationship between the pile base load and the pile base settlement is also addressed in this model. The nonlinearity of the pile concrete placed under an axial pressure force is also considered in the calculations by adopting the Hognestad model. The interaction between identical piles is analyzed, and the soil outside the disturbed zone is considered as an elastic medium. This approach, first studied for a single pile, is then extended to study pile groups through the principle of superposition. The calculated results obtained from this proposed method and the measurements of full-scale load tests on a single pile and pile groups are compared to verify the effectiveness and accuracy of the proposed method. It is shown that reasonable predictions can be made by means of the method proposed in this paper.