1991 Volume 24 Issue 1 Pages 45-50
The electroosmotic dewatering of a homogeneous semisolid material is investigated. The basic differential equation for electroosmosis through compressible materials is derived by use of Kobayashi’s equation, which considers the tortuosity of a flow path and the effect of the hydraulic pressure profile in the materials. It is recognized from Kobayashi’s equation that at the impermeable upper wall the electroosmotic flow and the pressure flow compensate each other. The relation among local hydraulic pressure, solid compressive pressure and external pressure is also derived, and is the same as those in mechanical filtration and expression. It is assumed in the analysis that no electroosmotic flow occurs in the layer where the local void ratio is smaller than a certain critical value. Based on numerical calculation, the pressure flow opposed to the net flow propagates from the upper electrode to the lower electrode. The electroosmotic dewatering rates of a homogeneous bentonite clay material calculated by the present method compare favorably with experimental observations.
