The permeability of dredged material-bentonite backfills

Extensive attention has been paid to the treatment and disposal of dredged material, and there is a need to clarify the feasibility of recycling dredged material by using it as backfill in soil-bentonite vertical cutoff walls. By setting the dredged material in the Baimao storage yard of Meiliang Bay in Taihu Lake and bentonite as the research objects, this paper studied the influences of bentonite content, confining pressure and pore size distribution on the permeability of dredged material-bentonite backfills. According to the test results, from the perspective of medium-term and short-term permeability, it is feasible to recycle dredged material by using it as backfill in a vertical cutoff wall. The permeability of the dredged material-bentonite soil mixture decreases with increasing bentonite content, but the degree of decrease is not significant. At the same time, the higher the confining pressure is, the smaller the variation in hydraulic conductivity with bentonite content. The permeability of the soil mixture decreases with increasing confining pressure, and the range of reduction is within a certain order of magnitude. Moreover, the confining pressure has a similar impact on the decrease in the permeability of the soil mixtures with different bentonite contents. The hydraulic conductivity of the dredged material-bentonite mixture decreases because the addition of bentonite changes the pore size distribution and reduces the porosity and characteristic pore size D₅₀ of the soil mixture.