Water movement through a swelling material

Soil Research ◽  
1965 ◽  
Vol 3 (1) ◽  
pp. 11 ◽  
Author(s):  
AV Blackmore ◽  
TJ Marshall
Keyword(s):  
Hydrostatic Pressure ◽  
Hydraulic Conductivity ◽  
Pressure Drop ◽  
Porous Material ◽  
Double Layer ◽  
Void Ratio ◽  
Electrolyte Concentration ◽  
Water Movement ◽  
Field Conditions ◽  
Sodium Montmorillonite

The effect of the drag of a fluid on the porous material through which it flows is examined for a swelling material. It is shown that, when equilibrium is established between drag and swelling in films of oriented sodium montmorillonite, there is a decrease in void ratio in the material in the direction of flow. This effect of drag increases with decreasing electrolyte concentration of the permeating solution, in accord with double-layer theory, and with increasing drop in hydrostatic pressure across the film. Hydraulic conductivity was found to increase with decreasing electrolyte concentration of the permeating solution, contrary to usual experience. The cause of this is considered to be the increase in spacing corresponding to decrease in concentration. Hydraulic conductivity of unconfined film at equilibrium was found to decrease with increasing drop in hydrostatic pressure across the film. An increase in the pressure drop causes a decrease in the spacing of the clay, particularly towards the base of the film, so that the hydraulic conductivity of the whole film is lowered. Consequently Darcy's law does not hold for these films. Implications for less ordered swelling systems are considered briefly. The effect of drag on soils under field conditions will ordinarily be negligible.

Predicting the saturated hydraulic conductivity of sand and gravel using effective diameter and void ratio

2004 ◽  
Vol 41 (5) ◽  
pp. 787-795 ◽  
Author(s):  
Robert P Chapuis
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Saturated Hydraulic Conductivity ◽  
Effective Diameter ◽  
Predictive Capacity ◽  
K Value ◽  
Maximum Value ◽  
New Equation ◽  
Silty Soils ◽  
Sand And Gravel

This paper assesses methods to predict the saturated hydraulic conductivity, k, of clean sand and gravel. Currently, in engineering, the most widely used predictive methods are those of Hazen and the Naval Facilities Engineering Command (NAVFAC). This paper shows how the Hazen equation, which is valid only for loose packing when the porosity, n, is close to its maximum value, can be extended to any value of n the soil can take when its maximum value of n is known. The resulting extended Hazen equation is compared with the single equation that summarizes the NAVFAC chart. The predictive capacity of the two equations is assessed using published laboratory data for homogenized sand and gravel specimens, with an effective diameter d10 between 0.13 and 1.98 mm and a void ratio e between 0.4 and 1.5. A new equation is proposed, based on a best fit equation in a graph of the logarithm of measured k versus the logarithm of d102e3/(1 + e). The distribution curves of the differences “log(measured k) – log(predicted k)” have mean values of –0.07, –0.21, and 0.00 for the extended Hazen, NAVFAC, and new equations, respectively, with standard deviations of 0.23, 0.36, and 0.10, respectively. Using the values of d10 and e, the new equation predicts a k value usually between 0.5 and 2.0 times the measured k value for the considered data. It is shown that the predictive capacity of this new equation may be extended to natural nonplastic silty soils, but not to crushed soils or plastic silty soils. The paper discusses several factors affecting the inaccuracy of predictions and laboratory test results.Key words: permeability, sand, prediction, porosity, gradation curve.

INFLUENCE OF AMMONIUM ON THE BEHAVIOR OF CLAY PARTICLES IN A SODIC SOIL AND BENTONITE

1974 ◽  
Vol 54 (1) ◽  
pp. 39-44 ◽  
Author(s):  
J. C. VAN SCHAIK ◽  
R. R. CAIRNS
Keyword(s):  
Hydraulic Conductivity ◽  
Beneficial Effect ◽  
Salt Concentration ◽  
Soil Type ◽  
Water Movement ◽  
Ammonium Salts ◽  
Sodic Soil ◽  
Clay Particles ◽  
Mobility Studies ◽  
Solonetz Soil

The addition of ammonium salts increased the hydraulic conductivity of samples taken from the Bnt horizon of a Solonetz soil. The improved conductivity was caused by an increase in the salt concentration in the soil solution and by the ammonium adsorbed on the clay particles. Since the dominant clay mineral in this soil type is montmorillonite, purified bentonite was used for comparative studies. Mobility studies of montmorillonite systems indicated that the adsorbed NH4 ions are tightly bound to the clay particles. The size of the NH4-tactoids was found to be larger than that of the Na-tactoids but less than half that of the Ca-tactoids. It was concluded that the beneficial effect of ammonium on water movement in Solonetz soils will be less than that of calcium, but the transformation of the adsorbed ammonium in the field, followed by replacement of sodium by hydrogen, may result in further improvement of these soils.

Hydraulische Leitfähigkeit von Valonia utricularis / Hydraulic Conductivity of Valonia utricularis

1971 ◽  
Vol 26 (12) ◽  
pp. 1302-1311 ◽  
Author(s):  
E. Steudle ◽  
U. Zimmermann
Keyword(s):  
Hydraulic Conductivity ◽  
Cell Membrane ◽  
Marine Alga ◽  
Water Movement ◽  
Turgor Pressure ◽  
Irreversible Thermodynamics ◽  
Rapid Changes ◽  
Cell Turgor ◽  
Valonia Utricularis

A method is described for the simultaneous determination of rapid changes of the cell turgor pressure (hydrostatic pressure) in algal cells (cell size must be at least 3 mm in diameter), and of the net volume flow across the cell membrane arising after a change of the cell turgor pressure or of the osmotic pressure in the outside medium. On the basis of the equations of irreversible thermodynamics it is possible to calculate the hydraulic conductivity of the cell membrane from these measurements, as it is theoretically shown.The hydraulic conductivities of the marine alga Valonia utricularis determined in two independent ways (by osmotic and hydrostatic experiments) are equal. For exosmosis, Lpex (hydrostatic) and Lpex (osmotic) amounted to (9,6 ± 1,0) ·10-7 and (9,8 ± 1,9) · 10-7 respectively cm · sec-1 · atm-1, and for endomosis, Lpen (hydrostatic) was (9,4 ± 1,1) ·10-7 cm · sec-1 · atm-1.A polarity in the water movement across the cell membranes as discussed in the literature could not be found for Valonia utricularis.

Effects of Chondroitin Sulphate on Fluid and Solute Transport during Peritoneal Dialysis in Rats

1991 ◽  
Vol 11 (4) ◽  
pp. 351-354 ◽  
Author(s):  
Andrzej Breborowicz ◽  
Maciej Radkowski ◽  
Jan Knapowski ◽  
Dimitrios G. Oreopoulos
Keyword(s):  
Peritoneal Dialysis ◽  
Hydrostatic Pressure ◽  
Hydraulic Conductivity ◽  
Horseradish Peroxidase ◽  
Solute Transport ◽  
Peritoneal Cavity ◽  
Chondroitin Sulphate ◽  
In Vitro Experiments ◽  
Fluid Removal

The effect of chondroitin sulphate (CS) on peritoneal fluid and solute transport was studied in rats undergoing peritoneal dialysis. In the presence of CS, net ultrafiltration increased, while absorption of glucose and horseradish peroxidase from the peritoneal cavity decreased. Albumin, used instead of CS, did not modify either fluid or solute transport. In in vitro experiments on isolated rabbit mesentery, CS decreased transmembrane water flow induced by hydrostatic pressure, and its effect was not fully reversed 60 minutes after “wash-out” of this glycosaminoglycan. We postulate that the polyanionic CS molecules are trapped in the peritoneal interstitium, thus decreasing its hydraulic conductivity and permeability, which in turn increases net fluid removal during peritoneal dialy sis because of its slower absorption from the peritoneal cavity.

A relation of hydraulic conductivity — void ratio for soils based on Kozeny-Carman equation

2016 ◽  
Vol 213 ◽  
pp. 89-97 ◽  
Author(s):  
Xingwei Ren ◽  
Yang Zhao ◽  
Qinglu Deng ◽  
Jianyu Kang ◽  
Dexian Li ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio

Improving the field estimation of saturated hydraulic conductivity in soil survey

Soil Research ◽  
1997 ◽  
Vol 35 (4) ◽  
pp. 803 ◽  
Author(s):  
Neil McKenzie ◽  
David Jacquier
Keyword(s):  
Hydraulic Conductivity ◽  
Water Movement ◽  
Saturated Hydraulic Conductivity ◽  
Soil Survey ◽  
Land Evaluation ◽  
Levels Of Detail ◽  
Eastern Australia ◽  
Field Estimation ◽  
Morphological Variables ◽  
Soil Surveys

Prediction of the movement and storage of water in soil is central to quantitative land evaluation. However, spatial and temporal predictions have not been provided by most Australian soil surveys. The saturated hydraulic conductivity (Ks) is an essential parameter for description of water movement in soil and its estimation has been considered too difficult for logistic and technical reasons. The Ks cannot be measured everywhere and relationships with readily observed morphological variables have to be established. However, conventional morphology by itself is a poor predictor of Ks. We have developed a more functional set of morphological descriptors better suited to the prediction of Ks. The descriptors can be applied at several levels of detail. Measurements of functional morphology and Ks were made on 99 horizons from 36 sites across south-eastern Australia. Useful predictions of Ks were possible using field texture, grade of structure, areal porosity, bulk density, dispersion index, and horizon type. A simple visual estimate of areal porosity was satisfactory, although a more quantitative system of measurement provided only slightly better predictions. Regression trees gave more plausible predictive models than standard multiple regressions because they provided a realistic portrayal of the non-additive and conditional nature of the relationships between morphology and Ks. The results are encouraging and indicate that coarse-level prediction of Ks is possible in routine soil survey. Direct measurement of Ks does not appear to be generally feasible because of the high cost, dynamic nature of Ks, and substantial short-range variation in the field. Prediction is further constrained by the limited returns from more sophisticated morphological predictors. The degree to which this limits practical land evaluation is yet to be demonstrated.

Hydrostatic pressure effect on double layer capacity of iron

2020 ◽  
Vol 871 ◽  
pp. 114306 ◽  
Author(s):  
Xilin Xiong ◽  
Xiaojuan Ban ◽  
Yu Yan ◽  
Yanjing Su
Keyword(s):  
Hydrostatic Pressure ◽  
Double Layer ◽  
Pressure Effect ◽  
Double Layer Capacity

Hydraulic conductivity of bentonite-sand mixtures

2000 ◽  
Vol 37 (2) ◽  
pp. 406-413 ◽  
Author(s):  
P V Sivapullaiah ◽  
A Sridharan ◽  
V K Stalin
Keyword(s):  
Hydraulic Conductivity ◽  
Water Retention ◽  
Void Ratio ◽  
Clay Content ◽  
Liquid Limit ◽  
Natural Soils ◽  
Waste Containment ◽  
Clay Liner

The use of bentonite alone or amended with natural soils for construction of liners for water-retention and waste-containment facilities is very common. The importance of bentonite content in reducing the hydraulic conductivity of liners is well recognised. The study illustrates the role of the size of the coarser fraction in controlling the hydraulic conductivity of the clay liner. It has been shown that at low bentonite contents the hydraulic conductivity of the liner varies depending on the size of the coarser fraction apart from clay content. At a given clay content, the hydraulic conductivity increases with an increase in the size of the coarser fraction. But when the clay content is more than that which can be accommodated within the voids of the coarser fractions, the hydraulic conductivity is controlled primarily by clay content alone. Four different methods of predicting hydraulic conductivity of the liners are presented. Using two constants, related to the liquid limit, the hydraulic conductivity can be predicted at any void ratio.Key words: clays, hydraulic conductivity, liquid limit, liners, void ratio.

Influence of sodium adsorption ratio on sodium and calcium breakthrough curves and hydraulic conductivity in soil columns

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 586 ◽  
Author(s):  
Oagile Dikinya ◽  
Christoph Hinz ◽  
Graham Aylmore
Keyword(s):  
Hydraulic Conductivity ◽  
Electrolyte Concentration ◽  
Soil Aggregates ◽  
Breakthrough Curves ◽  
Sodium Adsorption Ratio ◽  
Threshold Concentration ◽  
Critical Threshold ◽  
Soil Columns ◽  
Clay Particles ◽  
The Matrix

The paper examines the effects of electrolyte concentration and sodium adsorption ratio (SAR) on the relative saturated hydraulic conductivity (RHC) and the ionic behaviour of calcium (Ca) and sodium (Na) ions in the Na–Ca exchange complex. Batch binary exchange and saturated column transport experiments were carried out to quantify these effects using an agricultural Balkuling soil and a mining residue. Generally, RHC has been found to decrease with time, with increasing SAR, and with decreasing electrolyte concentration. The more rapid decrease in RHC in the mining residue, particularly at the lowest concentration (1 mmol/L), was consistent at all SAR values. The decreases in RHC were likely to be caused by partial blocking of pores by dispersed clay particles, as evidenced by the appearance of suspended clay particles in the effluent during leaching. Significant differences in RHC were observed in the passage of fronts of decreasing electrolyte concentrations for CaCl2 and SAR 15 solutions through the soil columns. These differences were attributable to structural alterations (slaking) of the media and the nature of the particles released and mobilised within the porous structure at any given point in the column. Measurements at the critical threshold concentration and turbidity concentration at SAR 15 revealed structural breakdown of the pore matrix system as evidenced by decreased RHC. The increase in SAR to 15 is initially accompanied by erratic RHC, presumably due to the break up of soil aggregates under the increased swelling forces. The less coherent mining residue soil was substantially more vulnerable to blockage of pores than the Balkuling soil in which clay particles are likely to be more readily mobilised, and hence available to re-deposit and occlude the matrix pores.

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