Effect of drains layout density on consolidation of layered slurry induced by PHDs-VP

Prefabricated horizontal drains (PHDs) combined with vacuum preloading (VP) presents distinct advantages over prefabricated vertical drains (PVDs) and has become a popular method for the treatment of dredged slurry. However, the effect of drains layout density on the consolidation characteristics of slurry has not been extensively investigated. This study addresses this gap by conducting three groups of experiments using the layered filling approach, one of which focused on the PHDs-PVDs-VP method. Throughout the consolidation process, water discharge and surface settlement were monitored. Post-consolidation, soil properties were assessed and shapes of prefabricated drains were examined. The results indicate that increased drains layout density accelerates consolidation rate. Additionally, using the layered filling approach can increase the treatment capacity of disposal sites by 25%, enhance the reinforcement effectiveness of deep soil layer, and achieve more uniform settlement. Moreover, the PHDs-PVDs-VP method can enhance the treatment effectiveness of slurry without the requirement for a substantial increase in drains layout density. These insights into the dewatering and reinforcement mechanisms offer valuable guidance for practical engineering applications.