Nonlinear Consolidation of Composite Foundations Reinforced with Pervious Concrete Piles: Analytical and Design-Oriented Solutions considering Porosity Effect

Pervious concrete piles, which combine high strength with excellent permeability, have demonstrated significant advantages in ground improvement applications. However, the theoretical framework for consolidation in composite foundations utilizing this pile type remains underdeveloped, and the lack of systematic design guidance has hindered its widespread engineering implementation. To address the existing research gap, this study proposes a composite ground improvement method based on the combination of permeable concrete piles with varying porosities. A nonlinear consolidation model for composite foundations is developed using logarithmic relationships between void ratio and effective stress (e–log σ′) and between void ratio and permeability (e–log k), while introducing a modified equal-strain assumption that accounts for pile penetration deformation. The governing consolidation equations are derived analytically, and the influence of key parameters on the consolidation behavior is systematically analyzed. The validity of the proposed solution is further verified through comparison with degenerate solutions and field-measured data. The results indicate that the three proposed consolidation models, featuring different pile arrangement strategies, can be flexibly applied to meet diverse engineering demands, thereby expanding the design framework for composite foundations using permeable concrete piles. The introduction of the modified equal-strain assumption significantly improves the accuracy of consolidation predictions and enhances design reliability. Furthermore, when the Cc/Ckh(v) > 1, neglecting the nonlinear behavior of the soil may lead to an overestimation of the consolidation rate. Compared with Cc/Ckh, the effect of Cc/Ckv on the consolidation rate is minimal and can be considered negligible. Additionally, the clogging effect of the pile has a pronounced impact on drainage efficiency during consolidation and should not be overlooked in practical applications.