Pore Pressures, Consolidation, and Electrokinetics

The pore-water pressures that develop when an electric field is introduced into a soil mass are shown to depend upon the voltage distribution and the ratio of the electrokinetic and hydraulic permeabilities of the soil. Thus, the magnitude of the pressures at a point depends upon electrode geometry. The time necessary for the development of these pore-water pressures is shown to be predictable by use of the theory of consolidation. The rate of pore-pressure development is dependent upon the hydraulic permeability of the soil and not upon its electrokinetic permeability. Whether soil stabilization occurs as a result of the development of negative porewater pressures or destabilization occurs due to positive pore water pressures, depends upon the boundary conditions at the electrodes. Secondary effects, from the point of view of large-scale engineering works, are associated with alterations in soil pH and conductivity. Laboratory and field test data are presented to substantiate the arguments presented.