Conventional consolidation theories for multi-element composite pile foundations often neglect the combined effects of non-ideal boundary drainage, nonlinear soil behaviour, and time-dependent drain clogging. This paper proposes a generalised nonlinear consolidation model incorporating these three aspects. Three types of analytical units – outward, inward, and bidirectional flow are developed for typical pile arrangements (e.g. triangular and square patterns). The model adopts a continuous drainage boundary for the foundation top, a nonlinear compression-permeability constitutive law for soil, and a time-dependent clogging function for prefabricated vertical drains (PVDs). Analytical solutions are derived for instantaneous and multi-stage loading. Validation against existing solutions shows: (1) Drain clogging significantly controls pore pressure dissipation; neglecting its temporal evolution leads to overestimation of consolidation rates. (2) Top drainage conditions exert a decisive influence; non-ideal permeable boundaries can substantially delay consolidation. (3) The ratio Cc/Ckh has a more pronounced effect on consolidation rate than Cc/Ckv (Cc is compression index, Ckh, Ckv is horizontal/vertical permeability index), because radial drainage dominates. (4) When bearing capacity requirements are satisfied, the combination of impervious piles and PVDs offers superior cost-effectiveness and consolidation performance compared to merely increasing pile stiffness. The proposed model provides a robust theoretical foundation for the design and analysis of composite foundations.
Dandan et al. (Fri,) studied this question.