Coefficient of Permeability from AC Electroosmosis Experiments. II: Results

Abstract

Alternating current (AC) electroosmosis tests, which permit rapid determination of the coefficient of permeability of saturated cohesive soils are described. The testing device was developed to minimize the adverse effects of prolonged application of direct current on observed responses. The apparatus and procedures to conduct the AC experiments are presented and results of 19 experiments are analyzed. In these tests, a weak AC is sinusoidally applied under nominally undrained boundary conditions to saturated kaolinite specimens; excess pore pressure and phase angle are measured at frequencies between 0.25 and 4 Hz. The results of the experimental program and the procedures of backcalculating the coefficient of permeability are presented. The coefficient of permeability from falling head permeability and AC electrosmosis tests on specimens of resedimented kaolinite are shown to agree within a factor of five. These data support the theoretical conclusions of the companion paper and suggest that this type of test is feasible to rapidly evaluate the coefficient of permeability of saturated cohesive soils in the laboratory.