Abstract
Changes in volume and pore space induced by the shrink-swell behavior of clay minerals present a challenge to predictive modeling of hydraulic properties of clayey soils. We present a pore-scale framework that combines physico-chemical processes with pore-geometrical, hydrostatic, and hydrodynamic considerations toward prediction of constitutive hydraulic relationships for swelling porous media. Variations in pore space are modeled by considering the soil clay fabric as an assembly of colloidal-size tactoids with lamellar structure. The arrangement of clay tactoids and the spacing between individual lamellae are functions of primarily clay hydration state quantifiable via the disjoining pressure that is dominated by a large electrostatic repulsive component. Solution chemistry and clay type are also considered. Silt and sand textural constituents are represented as rigid spheres interspaced by clay fabric in two basic configurations of "expansive" and "reductive" unit cells. Bulk soil properties such as clay content, porosity and surface area serve as constraints for modeling pore-space geometry. Liquid saturation within the idealized pore space is calculated as a function of chemical potential considering volume changes due to clay shrink-swell behavior. Closed-form expressions for prediction of unsaturated hydraulic conductivity are derived from calculations of average flow velocities in ducts, parallel plates, and in corners bounded by liquid-vapor interfaces, and invoking proportionality between flux density and hydraulic gradient. Measurements of saturated hydraulic properties are used to evaluate model predictions and lay the foundation for upscaling considerations to sample and profile scales. Advanced flexible-wall permeametry is employed to measure permeability of clay-sand mixtures with mono- and divalent ionic solutions. Preliminary pore-scale model calculations show favorable agreement with measured permeability values for a wide range of clay contents and varying ionic solutions. Copyright ASCE 2006.
| Original language | English (US) |
|---|---|
| Title of host publication | Geotechnical Special Publication |
| Pages | 2186-2197 |
| Number of pages | 12 |
| Edition | 147 |
| DOIs | |
| State | Published - 2006 |
| Externally published | Yes |
| Event | 4th International Conference on Unsaturated Soils - Carefree, AZ, United States Duration: Apr 2 2006 → Apr 5 2006 |
Other
| Other | 4th International Conference on Unsaturated Soils |
|---|---|
| Country | United States |
| City | Carefree, AZ |
| Period | 4/2/06 → 4/5/06 |
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ASJC Scopus subject areas
- Building and Construction
- Architecture
- Soil Science
Cite this
Hydraulic properties of swelling clay-sand mixtures : Microscale modeling and measurements. / Tuller, Markus; Or, D.
Geotechnical Special Publication. 147. ed. 2006. p. 2186-2197.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - Hydraulic properties of swelling clay-sand mixtures
T2 - Microscale modeling and measurements
AU - Tuller, Markus
AU - Or, D.
PY - 2006
Y1 - 2006
N2 - Changes in volume and pore space induced by the shrink-swell behavior of clay minerals present a challenge to predictive modeling of hydraulic properties of clayey soils. We present a pore-scale framework that combines physico-chemical processes with pore-geometrical, hydrostatic, and hydrodynamic considerations toward prediction of constitutive hydraulic relationships for swelling porous media. Variations in pore space are modeled by considering the soil clay fabric as an assembly of colloidal-size tactoids with lamellar structure. The arrangement of clay tactoids and the spacing between individual lamellae are functions of primarily clay hydration state quantifiable via the disjoining pressure that is dominated by a large electrostatic repulsive component. Solution chemistry and clay type are also considered. Silt and sand textural constituents are represented as rigid spheres interspaced by clay fabric in two basic configurations of "expansive" and "reductive" unit cells. Bulk soil properties such as clay content, porosity and surface area serve as constraints for modeling pore-space geometry. Liquid saturation within the idealized pore space is calculated as a function of chemical potential considering volume changes due to clay shrink-swell behavior. Closed-form expressions for prediction of unsaturated hydraulic conductivity are derived from calculations of average flow velocities in ducts, parallel plates, and in corners bounded by liquid-vapor interfaces, and invoking proportionality between flux density and hydraulic gradient. Measurements of saturated hydraulic properties are used to evaluate model predictions and lay the foundation for upscaling considerations to sample and profile scales. Advanced flexible-wall permeametry is employed to measure permeability of clay-sand mixtures with mono- and divalent ionic solutions. Preliminary pore-scale model calculations show favorable agreement with measured permeability values for a wide range of clay contents and varying ionic solutions. Copyright ASCE 2006.
AB - Changes in volume and pore space induced by the shrink-swell behavior of clay minerals present a challenge to predictive modeling of hydraulic properties of clayey soils. We present a pore-scale framework that combines physico-chemical processes with pore-geometrical, hydrostatic, and hydrodynamic considerations toward prediction of constitutive hydraulic relationships for swelling porous media. Variations in pore space are modeled by considering the soil clay fabric as an assembly of colloidal-size tactoids with lamellar structure. The arrangement of clay tactoids and the spacing between individual lamellae are functions of primarily clay hydration state quantifiable via the disjoining pressure that is dominated by a large electrostatic repulsive component. Solution chemistry and clay type are also considered. Silt and sand textural constituents are represented as rigid spheres interspaced by clay fabric in two basic configurations of "expansive" and "reductive" unit cells. Bulk soil properties such as clay content, porosity and surface area serve as constraints for modeling pore-space geometry. Liquid saturation within the idealized pore space is calculated as a function of chemical potential considering volume changes due to clay shrink-swell behavior. Closed-form expressions for prediction of unsaturated hydraulic conductivity are derived from calculations of average flow velocities in ducts, parallel plates, and in corners bounded by liquid-vapor interfaces, and invoking proportionality between flux density and hydraulic gradient. Measurements of saturated hydraulic properties are used to evaluate model predictions and lay the foundation for upscaling considerations to sample and profile scales. Advanced flexible-wall permeametry is employed to measure permeability of clay-sand mixtures with mono- and divalent ionic solutions. Preliminary pore-scale model calculations show favorable agreement with measured permeability values for a wide range of clay contents and varying ionic solutions. Copyright ASCE 2006.
UR - http://www.scopus.com/inward/record.url?scp=33845539389&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33845539389&partnerID=8YFLogxK
U2 - 10.1061/40802(189)185
DO - 10.1061/40802(189)185
M3 - Conference contribution
AN - SCOPUS:33845539389
SN - 0784408025
SN - 9780784408025
SP - 2186
EP - 2197
BT - Geotechnical Special Publication
ER -