Experimental Study of the Clogging of Dredger Fills under Vacuum Preloading

• Published in: International journal of geomechanics Vol. 17; no. 12
• Main Authors: Lei, Huayang, Lu, Haibin, Liu, Jingjin, Zheng, Gang
• Format: Journal Article
• Language: English
• Published: Reston American Society of Civil Engineers 01-12-2017
• Subjects: Clogging; Coastal zone; Consolidation; Dredgers; Forming; Ground treatment; Hydrostatic pressure; Methods; Model testing; Moisture content; Mud; Pore water pressure; Prefabrication; Technical Papers; Vacuum; Vertical drains; Water content; Water discharge; Water pressure
• ISSN: 1532-3641; 1943-5622
• DOI: 10.1061/(ASCE)GM.1943-5622.0001028

AbstractThis paper presents an experimental investigation of the reinforcement effects of two vacuum-preloading methods by large-scale laboratory model tests: traditional vacuum preloading and multistaged vacuum preloading. The fill samples obtained from Tianjin, China were subjected to tests and the judge method, and formation time of clogging of these two vacuum-preloading methods was determined. The results show that clogging problems during vacuum preloading have a prodigious influence on ground treatment effect. Different vacuum-preloading methods have different clog-forming processes. The formation of clogging outside of prefabricated vertical drains (PVDs) can be determined from the amount of water discharge, rate of water discharge, amount of settlement, and pore-water pressure. The model test indicated that the multistage vacuum-preloading method is more effective than the traditional vacuum-preloading method under the tested conditions in the coastal area of Tianjin. In the scaled model, it was observed that a clogging mud layer began forming at approximately 4,500–5,500 min and was fully formed between 35,000–40,000 min when using the traditional vacuum-preloading method. With the multistaged preloading method, the forming time and full formed time changed to 1,000–3,000 and 15,000 min. The observations on the average degree of consolidation demonstrate that the multiloading method is beneficial for foundation reinforcement as well. These test and discussion results are useful for overcoming the challenges of clogging that occurs during vacuum preloading in coastal areas.