Research on deposition and consolidation behaviour of cohesive sediment with settlement column experiment

Abstract

The deposition and consolidation behaviour of cohesive sediment is studied with a newly developed integrated settlement column system. This system, which includes graduate (glass) and settlement column (PMMA), has been proved an effective way to study the settlement of sediment suspension with 20∼300 g/L initial concentration. Cohesive sediment deposition and consolidation behaviours are as follows: cohesive sediment settlement can be divided into different stages as the initial free settlement and the consolidation settlement with different sediment interface rate. Cohesive sediment settlement influence factors are mainly the initial concentration and the settlement height, from which, settlement column size effect is determined by three factors as the wall effect, convection effect as well as the flocculation effect. During the final weight consolidation stage, deposited sediment consolidation settlement develops much faster than the excessive pore-pressure dissipation, and the fitted nonlinear consolidation constitutive relationship also can be obtained through deposited sediment layer sampling method. Results from this study indicate that the newly developed integrated settlement column system can effectively simulate the cohesive sediment suspension deposition and consolidation, and the nonlinear consolidation characteristics also can be studied through further experiments.