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.

Keywords:

• Model tests
• newly dredged fills
• air-booster vacuum preloading
• mechanism
• microstructure

Acknowledgments

The authors greatly appreciate the financial support from the National Natural Science Foundation of China, the Open Project of State Key Laboratory of Disaster Reduction in Civil Engineering and the Beijing-Tianjin-Hebei Special Projects of Cooperation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was financially supported by the National Natural Science Foundation of China (NSFC) [grant 51578371], the Open Project of State Key Laboratory of Disaster Reduction in Civil Engineering [grant SLDRCE17-01] and the Beijing-Tianjin-Hebei Special Projects of Cooperation [grant 16JCJDJC40000].