A Fractal Model for Predicting Water and Air Permeabilities of Unsaturated Fractured Rocks

Monachesi, Leonardo Bruno; Guarracino, Luis

doi:10.1007/s11242-011-9815-9

Cited by 15 publications

(15 citation statements)

References 30 publications

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“…Then, Assouline [2] developed a model to predict the relative hydraulic conductivity based on the first two moments of the water retention curve. In the particular case of fractured rocks, a physical constitutive model based on fractal geometry has been proposed by Guarracino [18] and, Monachesi and Guarracino [33]. Constitutive models describe hydraulic parameters at the representative elementary volume (REV) scale.…”

Section: Introductionmentioning

confidence: 99%

A Simple Hysteretic Constitutive Model for Unsaturated Flow

2017

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In this paper we present a constitutive model to describe unsaturated flow that considers the hysteresis phenomena. This constitutive model provides simple mathematical expressions for both saturation and hydraulic conductivity curves, and a relationship between permeability and porosity. The model is based on the assumption that the porous media can be represented by a bundle of capillary tubes with throats or "ink-bottles" and a fractal pore size distribution. Under these hypotheses, hysteretic curves are obtained for saturation and relative hydraulic conductivity in terms of pressure head. However, a non-hysteretic relationship is obtained when relative hydraulic conductivity is expressed as a function of saturation. The proposed relationship between permeability and porosity is similar to the well-known Kozeny-Carman equation but depends on the fractal dimension. The performance of the constitutive model is tested against different sets of experimental data and previous models. In all of the cases the proposed expressions fit fairly well the experimental data and predicts values of permeability and hydraulic conductivity better than others models.

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Section: Introductionmentioning

confidence: 99%

A Simple Hysteretic Constitutive Model for Unsaturated Flow

2017

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“…In this case, RE is used with specific permeability constitutive relation and retention curve including the effect of fractures. The main research on the ECM are devoted to the development of effective retention and permeability curves in the presence of fractures (Guarracino and Quintana, 2009;Monachesi and Guarracino, 2011;Pouya et al, 2013). The dual porosity model, which can be seen as an improvement of the ECM, treats the fractured domains as dual interactive continua representing fractures and porous matrix, respectively (Brouyère, 2006;Kuráž, 2010).…”

Section: Introductionmentioning

confidence: 99%

An advanced discrete fracture model for variably saturated flow in fractured porous media

Koohbor

Fahs

Hoteit

et al. 2020

Advances in Water Resources

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“…Increasing levels of damage are represented by an increasing blending fraction. While theoretical functions based on idealized configurations or high-permeability surrogate materials produce the desired qualitative behavior of fractures, experimental datasets that might be used to quantitatively validate these or develop new functions are difficult to obtain [21] and "virtually nonexistent" ( [14], [22]). Reference [23] recently identified only References [16], [24] and [25] as experimental data reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Unsaturated Hydraulic Conductivity in Fractured Media Using the Multistep Outflow Method

Flach¹,

Dixon²,

Nichols³

2015

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The multistep outflow method is routinely used to characterize the unsaturated hydraulic conductivity of soils. The technique involves placing a soil sample in a pressure plate apparatus, subjecting the sample to multiple gas pressures in discrete steps through time, and measuring the transient volume of pore fluid extracted. Unsaturated hydraulic property values are estimated through inverse modeling of the experimental conditions. In this study the multistep outflow concept was applied to micro-cracked cementitious materials to assess the efficacy of the technique for these materials. The cementitious materials tested were salt-waste simulant grout samples artificially damaged through oven-drying. Compared to typical soils, fractured media exhibit higher saturated conductivity and lower air-entry pressure, and the volume of fluid extractable from fractures is much lower than soil porosity. To accommodate these material differences the standard test apparatus was modified to incorporate a higher conductivity ceramic pressure plate, a high-precision digital balance for logging outflow mass, a low volume (diameter) effluent line, multiple inline high-precision gas regulators, and a high-precision low-range pressure gauge. Testing to date indicates that the modified apparatus can provide a viable means to measure the unsaturated hydraulic properties of micro-fractured cementitious materials. However the accuracy/uniqueness of inverse modeling is limited by the inherent characteristics of fractured media: high saturated conductivity, low air-entry pressure, and strong non-linearities. Hydraulic property results in the form of van Genuchten / Mualem curves are presented for three fractured grout specimens. DOE Performance Assessments often involve cementitious barriers and/or waste forms that are predicted or assumed to degrade over time due to various mechanisms such as carbonation-influenced reinforcing steel corrosion, external sulfate attack, differential settlement, and seismic activity. Physical degradation typically takes the form of small-scale cracking / fracturing, and the affected materials reside in unsaturated hydrogeologic zones. In these cases, unsaturated hydraulic properties are needed for fractured cementitious materials to simulate moisture movement and contaminant transport within and around the facility. The outflow extraction method, as implemented in the present study, provides a suitable method for estimating these material properties.

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A Fractal Model for Predicting Water and Air Permeabilities of Unsaturated Fractured Rocks

Cited by 15 publications

References 30 publications

A Simple Hysteretic Constitutive Model for Unsaturated Flow

A Simple Hysteretic Constitutive Model for Unsaturated Flow

An advanced discrete fracture model for variably saturated flow in fractured porous media

Characterization of Unsaturated Hydraulic Conductivity in Fractured Media Using the Multistep Outflow Method

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