Journal ArticleDOI
Effects of Porous Medium Heterogeneity on Vadose Zone Desiccation: Intermediate-Scale Laboratory Experiments and Simulations
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In this paper, a series of four intermediate-scale flow cell experiments was conducted in homogeneous and simple layered heterogeneous porous medium systems to investigate the effects of heterogeneity on desiccation of unsaturated porous media.Abstract:
Soil desiccation (drying), involving water evaporation induced by dry gas injection, is a potentially robust vadose zone remediation process to limit contaminant transport through the vadose zone. A series of four intermediate-scale flow cell experiments was conducted in homogeneous and simple layered heterogeneous porous medium systems to investigate the effects of heterogeneity on desiccation of unsaturated porous media. The permeability ratios of porous medium layers ranged from about five to almost two orders of magnitude. The insulated flow cell was equipped with twenty humidity and temperature sensors and a dual-energy gamma system was used to determine water saturations at various times. The multiphase code STOMP was used to simulate the desiccation process. Results show that injected dry gas flowed predominantly in the higher permeability layer and delayed water removal from the lower permeability material. For the configurations tested, water vapor diffusion from the lower to the higher permeability zone was considerable over the duration of the experiments, resulting in much larger relative humidity values of the outgoing air than based on permeability ratios alone. Acceptable numerical matches with the experimental data were obtained when an extension of the saturation-capillary pressure relation below the residual water saturation was used. The agreementsmore » between numerical and experimental results suggest that the correct physics are implemented in the simulator and that the thermal and hydraulic properties of the porous media, flow cell wall and insulation materials were properly represented.« lessread more
Citations
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Journal ArticleDOI
Mathematical framework for unsaturated flow in the finite deformation range
Xiaoyu Song,Ronaldo I. Borja +1 more
TL;DR: In this paper, a mathematical framework for coupled solid-deformation/fluid-diffusion in unsaturated porous material considering geometric nonlinearity in the solid matrix is presented, which relies on the continuum principle of thermodynamics to identify an effective or constitutive stress for a solid matrix, and a water-retention law that highlights the interdependence of the degree of saturation, suction, and porosity of the material.
Journal ArticleDOI
Finite Deformation and Fluid Flow in Unsaturated Soils with Random Heterogeneity
Xiaoyu Song,Ronaldo I. Borja +1 more
TL;DR: In this paper, the authors present a fully coupled hydromechanical formulation in the finite deformation range that incorporates the variation of degree of saturation with the Kirchhoff suction stress and the Jacobian determinant of the solid phase motion.
Journal ArticleDOI
Monitoring Vadose Zone Desiccation with Geophysical Methods
Michael J. Truex,Timothy C. Johnson,Christopher E. Strickland,John E. Peterson,Susan S. Hubbard +4 more
TL;DR: In this paper, Neutron moisture logging, electrical resistivity tomography, and cross-hole ground-penetrating radar approaches were evaluated with respect to their ability to provide effective spatial and temporal monitoring of desiccation during a treatability study conducted in the vadose zone of the USDOE Hanford site in the state of Washington.
Journal ArticleDOI
Field-Scale Assessment of Desiccation Implementation for Deep Vadose Zone Contaminants
Michael J. Truex,Martinus Oostrom,Christopher E. Strickland,Glen B. Chronister,Mark W. Benecke,Christian D. Johnson +5 more
TL;DR: In this paper, desiccation of the vadose zone has the potential to reduce the flux of contaminants to underlying groundwater by removing moisture and decreasing the aqueous-phase permeability of the desiccated zone.
Journal ArticleDOI
Contaminants in Vadose Zone Environments
TL;DR: 12 papers present novel approaches to characterize, monitor, remediate, and predict the transport and fate of contaminants in vadose zone environments.
References
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A closed-form equation for predicting the hydraulic conductivity of unsaturated soils
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TL;DR: Van Genuchten et al. as mentioned in this paper proposed a closed-form analytical expression for predicting the hydraulic conductivity of unsaturated soils based on the Mualem theory, which can be used to predict the unsaturated hydraulic flow and mass transport in unsaturated zone.
Journal ArticleDOI
A new model for predicting the hydraulic conductivity of unsaturated porous media
TL;DR: In this article, a simple analytic model is proposed which predicts the unsaturated hydraulic conductivity curves by using the moisture content-capillary head curve and the measured value of the hydraulic conductivities at saturation.
Journal ArticleDOI
Fundamentals of desiccation cracking of fine-grained soils: experimental characterisation and mechanisms identification
Hervé Peron,Hervé Peron,Tomasz Hueckel,Tomasz Hueckel,Lyesse Laloui,Lyesse Laloui,liangbu hu,liangbu hu +7 more
TL;DR: In this article, the results of a comprehensive experimental study of the desiccation of fine-grained soils were presented, which revealed that unconstrained drying exhibits two stages: a domain with large, mostly irrecoverable deformations and degree of saturation close to 100%, followed by another domain with lower defor- mations at a decreasing degree of satura- tion.
Journal ArticleDOI
Characterization of Miller‐Similar Silica Sands for Laboratory Hydrologic Studies
TL;DR: In this article, the authors present a comprehensive set of hydrologically relevant properties for a unique set of commercially available silica sands, including high sphericity, high batch-to-batch consistency, Miller-similarity, and availability in large quantities.
Journal ArticleDOI
Coupling of heat, water vapor, and liquid water fluxes to compute evaporation in bare soils
Marco Bittelli,Francesca Ventura,Gaylon S. Campbell,Richard L. Snyder,Fabia Gallegati,Paola Rossi Pisa +5 more
TL;DR: In this paper, a fully coupled numerical model is proposed to solve the governing equations for liquid water, water vapor, and heat transport in bare soils, and the numerical model with detailed measurements of soil temperature, heat flux, water content, and evaporation from the surface, and different formulations for the soil surface resistance parameter and test their effect on soil water content near the surface.