AN APPROACH TO QUICK DETERMINATION OF SOME WATER TRANSMISSION CHARACTERISTICS OF POROUS MEDIA

Abstract

We conducted capillary rise experiments with water in glass beads and soils. The validity of Poiseuille's law was verified in the first time segment by the straight line plots obtained between wetting front rise velocity dZ/dt and the inverse of the wetting front rise 1/Z. The values of the penetration coefficient γ and hydraulic conductivity K derived from first time segment capillary rise data using Poiseuille's analysis matched those measured independently. Predicted values of equivalent radius matched those determined by the mercury intrusion technique. The shape factor G of a porous medium is much higher than its theoretical value 8 in a single capillary. It is defined to vary with the water-filled porosity f and the formation factor e (G = 8/f + e). An empirical relation between permeability k and formation factor e allows the speedy estimation of shape factor G, equivalent radius r, and advancing contact angle α from derived water transmission constants. We show that capillary rise data of the first time segment are sufficient for physical characterization of soils in terms of water transmission constants (γ and k) and pore geometrical properties (e, G, and r).