Abstract: Existing laboratory model tests evidence that the prefabricated horizontal drain (PHD) vacuum preloading method exhibits significant potential for consolidating dredged slurry with high water content. However, systematic research on the practical engineering effectiveness of this method remains limited, with few related reports. To address this, a field experiment was conducted to rapidly consolidate marine dredged sediments used as fill material, employing the PHD vacuum preloading method. The experiment systematically evaluated the method’s treatment efficiency and effectiveness. Additionally, numerical modeling analysis was performed to validate the applicability and accuracy of the numerical model. Based on parameter sensitivity analysis, recommended ranges for key design parameters, including the horizontal spacing of drains and vertical layer spacing, were proposed for slurry with varying properties. Furthermore, a comparative analysis of multiple methods for treating dredged slurry was conducted, demonstrating that the PHD vacuum preloading method significantly enhances drainage consolidation efficiency. Early implementation of the vacuum preloading process was found to substantially improve consolidation effectiveness. For the treatment of high-compressibility soil slurry with a high initial void ratio, it is recommended that the horizontal spacing parameter of the drains (defined as the ratio of the horizontal spacing to the width of the drain) be set in the range of 5–8, and that the interlayer spacing parameter (defined as the ratio of the interlayer spacing to the total initial thickness of the slurry) be set within 0.1–0.3.

Key words: dredged soil slurry, prefabricated horizontal drain (PHD), vacuum consolidation, field experiment, numerical analysis