COEFFICIENT OF PERMEABILITY FROM AC ELECTROOSMOSIS EXPERIMENTS .1. THEORY

Electroosmosis techniques have been used in geotechnical and geoenviro nmental engineering applications. However, due to electrochemical chan ges and gas generation at the electrodes as a result of prolonged appl ication of a direct current electric field, its application in determi ning soil properties has been limited. A methodology, which uses a wea k alternating current (AC) as the driving force is developed to minimi ze these adverse effects. The governing partial differential equation for one-dimensional AC electroosmosis is presented for an experimental situation in a companion paper. Three boundary conditions, which refl ect the possible range for a closed boundary are identified. Transient and steady-state solutions are given for the ideal undrained boundary conditions. Analytical steady-state solutions are given for the two n ominally undrained boundary conditions. These solutions indicate that both small deformations of the boundary cavity and impedance effects d ue to relatively low permeability of an equivalent porus stone play an important role in the pore-pressure responses. Procedures based on th e steady-state solutions for backcalculating the coefficient of permea bility are presented.