Static batch settling behaviors of dredged and filled sediment and its steady-state macroscopic evaluation criteria

The static batch settling behaviors and mechanism of dredged and filled sediment and its steady-state macroscopic evaluation criteria have not been studied in depth yet. This is one of the main reasons why the optimal start-up time cannot be scientifically judged when the dredged and filled sediment foundations are treated by the vacuum filtration drainage consolidation technology today. In view of this, a theoretical study on the static batch settling behaviors of the dredged and filled sediment is conducted, and the theoretical relationship between the settling velocity of particle suspension and the average pore ratio is established. Based on the dredged and filled sediment from typical engineering sites and the configured typical concentration specimens, the experimental researches on the static batch settling model are carried out. The results indicate that: (1) The content of clay particles (d < 0.005 mm) is one of key factors affecting the static batch settling behaviors and mechanism of the dredged and filled sediment. (2) The maximum particle flux Gmax often occurs at very low concentrations that are difficult to measure experimentally. The higher the viscous content, the more difficult it is to measure experimentally the maximum particle flux during static batch settlement. (3) For the dredged sediment whose clay content is within 40% to 60%, the cumulative change rate of the average porosity ratio of 60% to 75% can be taken as the criterion for evaluating the steady state of its batch settling process.