This research deals with the vacuum preloading of fine-grained soft tailings related to the Sungun copper mine through laboratory tests and theoretical analysis. Vacuum preloading tests are conducted in two groups using a newly configured radial consolidation apparatus. During the first group of tests, the suction intensity is maintained constant similar to conventional vacuum consolidation tests, and in the second group, the suction is removed at certain steps after starting the preloading to investigate the vacuum removal effect on consolidation behavior. The samples in the slurry form are tested under three suctions of 20 kPa, 30 kPa, and 40 kPa individually considering influences of the initial water content of samples, vacuum pressure distribution, smear zone parameters, well resistance, and the dimensions of the vertical drain. Experimental results indicated that the initial water content and suction intensity severely governed the ultimate vertical strain of the sample. Also, depending on removal time, the sample could experience settlement, swelling, or no volume change after removing the suction. In the second part of the study, the vacuum removal effect is included in a new analytical model for vacuum preloading based on the Darcian law to predict the excess pore pressure dissipation and vertical strains. The proposed solutions successfully led to highly accurate predictions for vertical strains observed through comparative tests on the copper tailings. Besides, the proposed model effectively reproduced measurements of an in-situ vacuum consolidation of soda-ash tailings on a site near Dalian Bay in China, and the results of a numerical study on vacuum removal for a project in Ballina, Australia, with maximum errors of approximately 7%.

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