Consolidation of soft soils improved by composite piles considering clogging effect

Composite pile with a stiffer core and gravel shell is a newly emerging column technology to improve soft soil by combining the advantages of accelerating consolidation and increasing loading bearing capacity. In practice, the composite piles may be constructed into various forms with different cross-sectional shapes. Moreover, soft soil particles may be transferred along with the seepage and intrude into the gravel shell and thereby clog them. In this paper, by converting the noncircular cross-sectional composite pile into a hollow cylindrical unit cell and considering the time-dependent clogging effect, an analytical model for the consolidation of composite ground stabilized by composite piles is proposed. Analytical solutions are then obtained for instantaneous loading and multi-stage instantaneous loading under the equal-strain condition. Moreover, the variation of the stress with depth caused by surcharge loading is also incorporated in the analysis. The feasibility of the solutions is verified by degenerating them to some previous solutions. Furthermore, the solutions are applied to a laboratory test to investigate consolidation. The predicted results are compared to the measured data and a good agreement is observed between them. Finally, a parametric study is conducted to investigate the influence of several parameters on consolidation behavior.