Three‐dimensional analytical continuum model for axially loaded noncircular piles in multilayered elastic soil

Abstract To investigate the settlement response, load transfer behavior, and geometric effect of noncircular piles, a general three‐dimensional (3D) analytical continuum model for axially loaded noncircular pile‐multilayered homogeneous soil systems is presented. In the analysis, both the vertical and horizontal soil displacement fields are considered, and the variations of the soil displacement components are described by the three displacement transfer functions along the x, y, and z directions. The governing differential equations of noncircular piles and soil are derived by applying the principle minimum potential energy and variational method to the pile‐soil system. A complex variable function conformal mapping technique is introduced to overcome the complex boundary conditions of the transfer functions. Then, the numerical solutions of all the governing differential equations are simultaneously solved following an iterative algorithm. The reliability of this approach is validated by comparing some pile and soil responses with the results from existing analytical solutions or a rigorous finite element analysis. Differences in the settlement response and the axial force distribution between noncircular and circular piles are observed. In addition, the pile shaft resistance along the perimeter of the cross‐sections shows that a greater load is required in order to fully mobilize the ultimate resistance of the noncircular piles. We also compare the stress () contours of some typical noncircular piles with a circular pile, which provides useful insights into the geometric effect.