Studies on water retention and its movement in film stage of coarse porous media
2004
Aoda, T. (Niigata Univ. (Japan). Faculty of Agriculture)
Abstract During drying process, soil water in liquid phase remains in the form of independent pendular ring at the contact point of soil particles. At this water content (film stage), water is in vapor, liquid and semi-solid phase. Semi-solid phased water adsorbs on the soil surface as film, and not able to move by pressure change. As far as continuous body, liquid phase water transmits pressure, and moves conform to Darcy's law. The other side, it is still not clear that the pressure transition and liquid water movement of pendular ring. Because most studies, which focused on unsaturated soil water movement, have been discussed energy state of water without proper physical analysis of the water phase. In this study, we measured the time series of water pressure and the diameter of pendular ring under the condition of various water levels in glass beads (diameter=24mm) media. Consequently, pendular ring in the film stage, 1) could not transmit pressure each other, 2) could not move by the change of water level, 3) decreased by the vapor diffusion, 4) could not represent the pressure value at the inspection plane, 5) does move with phase transition.
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