Electro-Osmosis in Soils

Summary The present paper shows that, from a practical point of view, the electro-osmotic transport of water may be assumed to be constant for all soils. The magnitude of the osmotic permeability was found to be k e =5 × 10 −5 cm. per sec. for for 1 volt per cm. By comparing k e , with the hydraulic permeability the heights to which the water can be shifted by electro-osmosis were computed and also measured by laboratory tests. For this purpose a special apparatus was constructed. The fact that with colloidal materials agreement between theoretical equilibrium heads and test results exist only for the short interval of time immediately after applying an electric potential was attributed to the development of cracks within the mass of material. The possibility of diverting the flow of pore-water away from cuttings is discussed and illustrated by practical examples. Some indications are given of the magnitude of the required consumption of energy for a few arrangements of electrodes. An explanation is also offered for the favourable effect of electro-osmosis on the consolidation of soft soil deposits.