QUASY-STEADY CENTRIFUGE METHOD FOR UNSATURATED HYDRAULIC CHARACTERIZATION

Centrifugal force is advantageous for hydraulic property measurement because it allows measurement of lower hydraulic conductivity values, faster experiments, and higher accuracy than methods relying on gravitational and matric driving forces. The great force permits measurement of properties and conditions that are otherwise impossible or impractical. The quasi-steady centrifuge (QSC) method is a variation of the steady-state centrifuge (SSC) method we have developed for relatively simple and inexpensive implementation and other features. It achieves these advantages by somewhat relaxing the criterion for steadiness of flow through the sample. This compromise entails an increase in measurement uncertainty, but to a degree that in most applications would be tolerable and well worth the gains in simplicity of apparatus, larger sample capacity, and adaptability to various machines and operating conditions. We have tested this new experimental approach with easily constructed apparatus to establish a quasi-steady flow of water in unsaturated porous rock samples.