Experimental study on sandwich type deep vacuum dewatering and consolidation of river and lake sediment

The article investigates effective methods for the ex-situ treatment and disposal of sediment from rivers and lakes, focusing particularly on rapid dehydration techniques. Specifically, it presents findings from experimental research into deep vacuum dewatering and consolidation of “sandwich”-type sediment, using rice, wheat, and canola straw as drainage materials. The study, conducted using sediment from Zhenjiang’s rivers and lakes, involved applying vacuum loads from below and conducting experiments under sealed conditions to analyze internal vacuum levels, pore water pressure dynamics, and changes in water content. Scanning Electron Microscope (SEM) images of the sediment and straw were also analyzed. Results demonstrated significant effectiveness in deep vacuum dewatering and consolidation of the sediment structure, thereby addressing challenges associated with poor drainage in deep sediment layers. Wheat straw proved most effective in this process, followed by rice straw, while canola straw exhibited the least favorable outcomes. The transfer of vacuum levels was most rapid in wheat straw sediment, slower in rice straw, and slowest in canola straw. Additionally, negative pore water pressure gradually transferred from the bottom to the top of the sediment model. The efficiency of sediment dehydration was found to correlate with the stiffness and surface characteristics of the straw materials used. These research findings offer theoretical insights and technological advancements crucial for the management and treatment of river and lake sediment.