Soil-water characteristic curves of clays

2014 ◽  
Vol 51 (8) ◽  
pp. 869-883 ◽  
Author(s):  
Snehasis Tripathy ◽  
Mohd Yuhyi M. Tadza ◽  
Hywel Rhys Thomas
Keyword(s):  
Polyethylene Glycol ◽  
Water Content ◽  
Soil Water ◽  
Matric Suction ◽  
Degree Of Saturation ◽  
Chemical Analyses ◽  
Test Results ◽  
Characteristic Curves ◽  
Soil Water Characteristic Curves

The drying suction – water content soil-water characteristic curves (SWCCs) of three clays (MX80 bentonite, yellow bentonite, and Speswhite kaolin) were experimentally determined using axis-translation, vapour equilibrium, and osmotic techniques. The shrinkage paths of the clays were established from Clod tests. The suction – water content SWCCs in conjunction with the Clod test results enabled establishing the suction – degree of saturation SWCCs and further determination of the air-entry values (AEVs) of the clays. Chemical analyses of the polyethylene glycol (PEG) solutions in the osmotic tests revealed an imbalance of the osmotic suctions between the expelled and the retained salts on either side of semi-permeable membranes. A decrease in the water content due to an applied suction for clays with significant osmotic efficiencies was explained by two mechanisms. In mechanism 1, the water content decrease prior to the air entry is controlled by the interparticle repulsive pressure, and in mechanism 2, a decrease in the degree of saturation following the air entry is primarily due to the matric suction. The agreements between the AEVs of the clays determined based on the osmotic suctions corresponding to various applied suctions and that determined from the suction – degree of saturation SWCCs were found to be very good.

scholarly journals Effect of initial gravimetric water content and cyclic wetting-drying on soil-water characteristic curves of disintegrated carbonaceous mudstone

2019 ◽  
Vol 1 (3) ◽  
pp. 230-240
Author(s):  
Ling Zeng ◽  
Fan Li ◽  
Jie Liu ◽  
Qianfeng Gao ◽  
Hanbing Bian
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Initial Water Content ◽  
Test Results ◽  
Initial Water ◽  
Soil Water Characteristic Curves ◽  
Water Holding ◽  
Gravimetric Water Content ◽  
Plate Apparatus

Abstract The soil-water characteristic curve (SWCC) is often used to estimate unsaturated soil properties (e.g. strength, permeability, volume change, solute and thermal diffusivity). The SWCC of soil samples is significantly affected by cyclic wetting-drying. To examine how water content and cyclic wetting-drying affect the SWCC of disintegrated carbonaceous mudstone (DCM), SWCC tests were implemented using a pressure-plate apparatus. In addition, SWCC models for DCM considering the initial gravimetric water content and cyclic wetting-drying were developed. The test results showed that the volumetric water content (θ) of the DCM first decreased rapidly and then became stable as matric suction (s) increased. The initial water content affected the SWCC by altering the pore structure of the DCM. For a given number of wetting-drying cycles, the higher the initial water content, the higher the stabilized θ. At a given s value, θ decreased as the number of wetting-drying cycles increased, which suggests that cyclic wetting-drying reduces the water-holding capacity of DCM. The Gardner model for DCM was constructed considering initial water content and cyclic wetting-drying, and was effective at describing and predicting the SWCC model for DCM.

Density Influence on Matric Suction of the Eolian Sand under the Condition of Loop of Dehumidifying and Humidifying Process

2011 ◽  
Vol 250-253 ◽  
pp. 2157-2160
Author(s):  
Yan Xun Song ◽  
Qiang Xu ◽  
Xi An Li ◽  
Hong Zhou Lin
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Matric Suction ◽  
Dry Density ◽  
Test Results ◽  
Unsaturated Sand ◽  
Water Characteristics ◽  
Eolian Sand ◽  
The Relationship ◽  
Variation Tendency

The matric suction has very important influence on the characteristics of unsaturated sand; and it is closely relevant to density. In order to discuss the relationship among the matric suction, water content and dry density, the matric suction of the eolian sand were measured in laboratory. The soil-water characteristics curves for unsaturated eolian sand with different dry densities are obtained. The test results show that the variation tendency of soil-water characteristics curves has been corresponding to the different densities.

Factors affecting drying and wetting soil-water characteristic curves of sandy soils

2004 ◽  
Vol 41 (5) ◽  
pp. 908-920 ◽  
Author(s):  
Hong Yang ◽  
Harianto Rahardjo ◽  
Eng-Choon Leong ◽  
D G Fredlund
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Soil Water ◽  
Grain Size Distribution ◽  
Sandy Soils ◽  
Water Entry ◽  
Matric Suction ◽  
Dry Density ◽  
Characteristic Curves ◽  
Soil Water Characteristic Curves

Drying and wetting soil-water characteristic curves (SWCCs) for five sandy soils are investigated using a Tempe pressure cell and capillary rise open tube. The test data are fitted to two SWCC equations using a least-squares algorithm. The obtained fitting parameters and some hysteretic behaviour are discussed and correlated with grain-size distribution parameters. A concept of total hysteresis is proposed to quantify the hysteresis of SWCC. The measured SWCC for one soil is also compared with the SWCC estimated from its grain-size distribution. The SWCC was also obtained at a high dry density for one of the soils. The results show that the shapes of the SWCCs are similar to the grain-size distributions of the soils and are affected by the dry density of the soil. A coarse-grained soil has a lower air-entry value, residual matric suction, and water-entry value and less total hysteresis than a fine-grained soil. The residual matric suction and water-entry value tend to approach the same value when the effective grain size D10 of the soil is small, in the range of 3-6 mm. SWCCs of uniform soils have steeper slopes and less total hysteresis than those of less uniform soils. Soils with a low dry density have a lower air-entry value and residual matric suction than soils with a high dry density. The SWCC predicted from grain-size distribution is found to be sufficiently accurate.Key words: soil-water characteristic curve, water content, suction, hysteresis, grain size.

Time-domain reflectometry measurements and soil-water characteristic curves of coarse granular materials used in road pavements

2007 ◽  
Vol 44 (7) ◽  
pp. 858-872 ◽  
Author(s):  
Jonas Ekblad ◽  
Ulf Isacsson
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Granular Materials ◽  
Time Domain ◽  
Characteristic Curve ◽  
Road Construction ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content ◽  
Characteristic Curves ◽  
Soil Water Characteristic Curves

Coarse granular materials are used extensively in road construction. Bearing capacity can be affected by the water content in the layers of these materials. The ability to estimate water content and to infer water movements is therefore important. The purpose of the work described herein was to determine soil-water characteristic curves and the relationship between relative apparent permittivity and volumetric water content for coarse (maximum particle size 90 mm) granular materials having various gradations. The relative apparent permittivity was measured with the aid of time-domain reflectometry (TDR), and the concurrent matric suction was measured with a tensiometer. Samples were prepared in a steel box and were heavily compacted, and TDR probes and a tensiometer cup were buried within the matrix. The variation in volumetric water content with apparent relative permittivity was found to deviate from the Topp et al. relationship. Soil-water characteristic curves were described using the Brooks–Corey and van Genuchten models. A pronounced hysteresis between wetting and drying paths was observed. For the low water retention coarse materials, measurements of water content might, in general, require correction because of the nonlinear distribution of water in the sample.Key words: pavement, time-domain reflectometry, soil-water characteristic curve, granular material.

Laboratory determination of Soil-Water Characteristic Curves for cracked soil

2010 ◽  
pp. 409-415 ◽  
Author(s):  
M Abbaszadeh ◽  
S Houston ◽  
C Zapata ◽  
W Houston ◽  
B Welfert ◽  
...  
Keyword(s):  
Soil Water ◽  
Characteristic Curves ◽  
Laboratory Determination ◽  
Soil Water Characteristic Curves ◽  
Cracked Soil

Measurement of soil-water characteristic curves for fine-grained soils using a small-scale centrifuge

2002 ◽  
Vol 39 (5) ◽  
pp. 1209-1217 ◽  
Author(s):  
R M Khanzode ◽  
S K Vanapalli ◽  
D G Fredlund
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Small Scale ◽  
Characteristic Curves ◽  
Pressure Plate ◽  
Soil Water Characteristic Curve ◽  
Fine Grained ◽  
Soil Water Characteristic Curves ◽  
Plate Apparatus

Considerably long periods of time are required to measure soil-water characteristic curves using conventional equipment such as pressure plate apparatus or a Tempe cell. A commercially available, small-scale medical centrifuge with a swinging type rotor assembly was used to measure the soil-water characteristic curves on statically compacted, fine-grained soil specimens. A specimen holder was specially designed to obtain multiple sets of water content versus suction data for measuring the soil-water characteristic curve at a single speed of rotation of the centrifuge. The soil-water characteristic curves were measured for three different types of fine-grained soils. The three soils used in the study were processed silt (liquid limit, wL = 24%; plasticity index, Ip = 0; and clay = 7%), Indian Head till (wL = 35.5%, Ip = 17%, and clay = 30%), and Regina clay (wL = 75.5%, Ip = 21%, and clay = 70%). The soil-water characteristic curves for the above soils were measured in 0.5, 1, and 2 days, respectively, using the centrifuge technique for suction ranges from 0 to 600 kPa. Time periods of 2, 4–6, and 16 weeks were required for measuring the soil-water characteristic curves for the same soils using a conventional pressure plate apparatus. There is reasonably good agreement between the experimental results obtained by the centrifuge and the pressure plate methods. The results of this study are encouraging as soil-water characteristic curves can be measured in a reduced time period when using a small-scale centrifuge.Key words: unsaturated soils, soil-water characteristic curve, centrifuge technique, soil suction, matric suction, water content.

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