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Velocity‐Gradient Relationships for Steady‐State Unsaturated Flow of Water in Nonswelling Artificial Soils
Author(s) -
Olson T. C.,
Swartzendruber D.
Publication year - 1968
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1968.03615995003200040014x
Subject(s) - kaolinite , soil water , tension (geology) , geotechnical engineering , flow velocity , porosity , porous medium , flow (mathematics) , water content , cohesion (chemistry) , chemistry , mineralogy , soil science , materials science , geology , mechanics , composite material , compression (physics) , physics , organic chemistry
The relationship between flow velocity and hydraulic gradient was studied for steady‐state unsaturated flow of water in horizontal columns of two nonswelling porous media, one a mixture of sand, ground silica, and kaolinite, and the other a mixture of sand and ground silica only. The flowing water contained 0.1% phenol to inhibit bacteria. Soil‐moisture tension was measured with three tensiometers positioned within the soil column. Gradients at different velocities could be determined at a single location. Tension changes were always from low to high, to eliminate hysteresis effects. This required the use of a graphical analysis to calculate corresponding values of velocity and gradient at a given constant tension. In general, essential proportionality between flow velocity and tension gradient at given tension was found for both materials. Very slight greater‐than‐proportional tendencies were present in the sand‐silica‐kaolinite mixture, but were not consistently related to tension. In the sand‐silica mixture a less‐than‐proportional flow response was observed at low and intermediate tensions, but became proportional as the tension increased. Minimal pore‐volume saturations achieved were 0.74 for the sand‐silica‐kaolinite, and 0.65 for the sand‐silica.