Unit Test and Coupled Model for Electroosmotic Consolidation and Heavy Metal Migration of Contaminated Soil

The electroosmosis method can be used to accelerate consolidation of dredged sediment and adsorb heavy metals in the sediment. A research method combining unit tests, theoretical analysis, and model tests is adopted in this study to investigate the large-scale deformation consolidation and heavy metal migration of saturated soft clay soil under the coupled effects of seepage, concentration, and electric field. Through unit tests, the variation laws of electric permeability coefficient, electromobility, and resistivity, considering the effects of void ratio and heavy metal concentration, are obtained. The test results demonstrate that the electrical permeability coefficient of contaminated soil is roughly positively linearly correlated with the void ratio. The electrical resistivity increases with time and decreases with increasing the concentration of heavy metals. The electromigration coefficient increases linearly with increasing void ratio and follows an exponential distribution with the increased concentration of heavy metals. Based on the variation laws, the coupled model for electroosmotic consolidation and heavy metal ion migration of contaminated soil is established by the piecewise linear finite difference method. The validity of the coupled model is verified by comparing the measured value of soil settlement from a laboratory model test and the calculated value of the theoretical model.