Experimental Study On The Consolidation Of Dredged Slurry By Vacuum Preloading With Prefabricated Horizontal Drain

The traditional vacuum preloading technology has some disadvantages such as long construction period,poor drainage effect and insufficient treatment effect on deep soil in the treatment of dredged slurry with high water content.Prefabricated horizontal drainage(PHD) can be vertical layered layout,which allows every layer of PHD can be directly connected to the vacuum pump and thus the bottom PHD also can have a very high vacuum pressure and,the the drainage paths of PHDs decrease owing to the vertical spacing of PHDs can decrease with the increase of the settlement.In this paper,the consolidation effect of PVD and PHD vacuum preloading on dredged slurry was compared and studied,and an improved PHD consolidation combined with horizontal drained geotextile(HDG) was proposed.The results show that the PHD vacuum preloading method has a better treatment effect on the deep soil mass.The treatment effect of the improved method has been significantly improved.Secondly,the paper implemented systematic research of the consolidation effects of different arrangements of HDG.The results show that laying two layers of HDGs around one PHD or only a layer of HDG on one side of PHD and the other side packaged with a small HDG strip have the same best treatment.Moreover,the PHDs treated by the two laying methods are still new,so the PHDs can be recycled.But the HDG consumption of later laying method is less and thus further save on the cost.At the end,the paper has conducted a separate PHD and membraneless PHD consolidation of two kinds of economical vacuum preloading method to study their feasibility and effectiveness.It is concluded that although the HDG can increase the drainage area,the drainage capacity of the PHD still has a great influence on the overall treatment effect.The vertical layering arrangement makes the dredged slurry above the PHD play a sealing role to a certain extent,but the final treatment effect is not still as good as when the geomembrane is spread.