Improved air-booster vacuum preloading method for newly dredged fills: Laboratory model study

Abstract

Newly dredged fills feature a high moisture content and a high floating mud content. Based on the conventional vacuum preloading (CVP) method, this article presents a new method of air-booster vacuum preloading (AVP) to reinforce newly dredged fills for different air-booster periods (45, 60 and 90 min). Compared with other methods, this new method features no sand cushion and adopts a self-developed air-booster pipe and a water–air separation device. A series of laboratory model tests were performed to explore the effect of the improved AVP method for the enhancement of newly dredged fills. A comparison of variables monitored during reinforcement (vacuum pressure, surface settlement, water discharge and pore-water pressure) and after reinforcement (water content, vane shear strength, SEM and MIP) indicates that the reinforcement effect of the AVP method is superior to that of the CVP method; the former can effectively alleviate the problem of prefabricated vertical drain (PVD) clogging, greatly reducing engineering costs and significantly shortening construction periods.