Large strain consolidation analysis of dredged sludge treated with multilayer PHDs combined with vacuum pressure

Multilayer PHDs combined with vacuum pressure for the treatment of dredged sludge yards are effective in avoiding the bending effect of drainage bodies during consolidation. However, the existing theory of self-weight consolidation cannot reflect the actual consolidation properties of dredged sludge treated with multilayer PHDs combined with vacuum pressure. In this study, the nonlinear large-strain consolidation model of dredged sludge treated with multilayer PHDs combined with vacuum pressure was established, considering the nonlinear compressibility and permeability of dredged sludge, self-weight stress of dredged sludge and the variation of dredged sludge height with time. The reliability of the model is verified by comparison with existing consolidation theory, indoor test, and field test data. By researching the effect of the PHDs laying ratios, the height of each dredged sludge layer, and the stacking process time on the consolidation rate of dredge sludge, it is found that if the total height of the treated dredged sludge is 9.0 m and the 5.0 m high yard is designed with double-layer PHDs, the optimal PHDs laying ratios is 20%, the optimal location of the 2nd layer PHDs is at half of the total height of dredged sludge and the optimal stacking time is 140 days.