Experimental analysis of a staged vacuum preloading method with PHD-PVD for waste slurry treatment

Construction waste slurry is used as backfill in construction engineering as a type of solid waste. However, the initial water content of the waste slurry is high and must be dewatered beforehand to realize its resource utilization. This study proposes a staged vacuum preloading (VP) method with prefabricated horizontal drain (PHD)-prefabricated vertical drain (PVD) to treat waste slurry considering the advantages of VP with PHD in waste slurry disposal. The effect of different vacuum loading modes on PHD-PVD on waste slurry treatment is analyzed through four groups of large-scale experimental model tests. The test results indicate that the staged VP with PHD-PVD can effectively alleviate the clogging compared to the effect of synchronous VP with PHD-PVD, and the effect of the soil drainage consolidation is improved. The apparent clogging is alleviated by the gradually increasing vacuum pressure applied to PHD and PVD, when combined with the results of the microstructure analysis. These findings can provide design criteria for waste slurry disposal in similar applications.