Consolidation of Land Reclamation Using PHD-VP: Nonlinear Analysis Considering the Clogging Effect and Time-Varying Vacuum Preloading

The use of prefabricated horizontal drains combined with vacuum preloading (PHD-VP) has emerged as a popular strategy for reinforcing land reclamation. This paper proposes a nonlinear analytical model to predict consolidation behavior of PHD-VP treated land reclamation. In this model, the PHD layers are treated as continuous drainage layers subjected to vacuum pressure, while the clogging effect and time-varying vacuum preloading are considered. Analytical solutions are derived for soil instantaneous and ramp filling conditions. The correctness and applicability of the proposed solutions are verified through degeneration analysis and a case study. A parametrical analysis is then conducted to investigate the influence of key parameters on consolidation. The results indicate that neglecting soil nonlinearity leads to overestimation of the degree of consolidation defined by stress and underestimation of the counterpart defined by strain. The clogging effect significantly retards consolidation, and the delay becomes more pronounced as the clogging severity increases. Moreover, increasing the designed maximum vacuum pressure enhances the rate of increase and the final magnitude of effective stress in the soil.