The Effect Equilibrium Solution Concentration and Sodium Adsorption Ratio on the Hydraulic Conductivity of Salt-Affected Soils.

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Date
2015-07-07
Authors
Khogali Suliman Hag hamid, hamid
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Publisher
uofk
Abstract
The effect of the concentration c and sodium adsorption ration SAR of fixed-salt solutions composed of calcium and sodium chloride on hydraulic conductively of three soils, one from Khartoum Province, and the other two from Blue Nile Province were studied. Swelling and dispersion processes which may influence the movement of these mixed-salt solutions through the soils were also investigated. The validity of two methods, McNeal's demixed-ion model and Lagerwerff et al. mixed-ion model for prediction of inter-layer swelling IS and relative hydraulic Y were tested. For the three soils the results showed that Y decreases as SAR increases and C decreases. The Y values predicted by McNeal's method for higher SAR and lower C gave better agreement with experimental Y. The three montmorillonitic soils exhibited qualitatively similar dispersion characteristics. The date showed that the dispersion index DI increases as SAR increases and C decreases. Rapid increase in dispersion was found when soil ESP increased from 0 to 49 in solutions of C 800 meg/L. The Drushab soil was found to be more dispersible than the other two soils. Highly significant correlation between DI and Y was obtained. The results showed that Macroscopic swelling MS of soils increases as ESP or SAR increases and C decreases. The three soils rendered qualitatively similar swelling characteristic indicative of similar mineralogy of the clay fraction. Threshold ESP values at which significant swelling occurs in solution of given C value are obtained which are comparable to those reported by other workers. The MS of the three montmorillonitic soils agreed qualitatively with McNeal's demixed-ion model. Lack of quantitative agreement was attributed to the procedure and to the use of whole soils instead of extracted clay fractions. Highly significant correlation between theoretical and experimental swelling was obtained. Lagerwerff et al. mixed-ion model failed to predict MS both qualitatively and quantitatively. A highly significant correlation between MS and Y was found. Threshold concentration required to maintain stable saturated flow in soil at a given ESP were calculated. The values were found to be greater than those reported previously by Quirk and Schofield. This is basically attributed to the amount of clay and mineralogical fractions.
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: The Effect Equilibrium Solution Concentration and Sodium Adsorption Ratio on the Hydraulic Conductivity of Salt-Affected Soils.
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