Experimental study on intermittent PHD-PVD vacuum preloading treatment of dredged slurry foundations

To address the issue of severe drainage plate clogging during the treatment of dredged slurry foundations using PHD-PVD (horizontal combined with vertical drainage plate) vacuum preloading, which leads to inadequate soil consolidation, the intermittent vacuum preloading method was adopted for improvement. This approach is referred to as PHD-PVD vacuum preloading combined with the intermittent method. The experimental program comprised five sets of laboratory model tests and a field test. Parameters including drainage volume, pore water pressure, and surface settlement were monitored during the reinforcement process of the dredged slurry, while the soil moisture content and shear strength were measured after testing. This was conducted to investigate the influence of intermittent vacuum preloading on the reinforcing effect of the dredged slurry.The experimental results show that, the intermittent PHD-PVD vacuum preloading significantly enhanced the reinforcing effect of dredged slurry foundations. Compared with the conventional PHD-PVD vacuum preloading, the intermittent PHD-PVD vacuum preloading group increased the drainage volume of dredged slurry by 14.69%, the settlement increased by 13.94%, and the vane shear strength increased by 21.30%. It indicates that the intermittent PHD-PVD vacuum preloading method effectively reduced the clogging near the drain, and the consolidation efficiency was improved. To verify the feasibility of this method for treating actual dredged slurry foundations, a field vacuum preloading test was conducted. The results confirmed that the method provides a significant reinforcing effect, offering valuable design guidance for similar projects in the future.