Mechanics of Fluid Flow Through a Porous Medium

Nield, D. A.; Bejan, Adrian

doi:10.1007/978-1-4757-3033-3_1

Cited by 7 publications

(3 citation statements)

References 27 publications

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“…Pore air motion of buoyancy-driven natural convection in the crushed rock highway embankment with a yearly harmonic surface temperature is a heat transfer problem of a twophase system consisting of a porous matrix saturated with a single incompressible flow [13]. Usually, it is assumed that local thermal equilibrium exists between the earth fill or crushed rock and the air and that Darcy's law can be satisfied approximately as long as the Prandtl-Darcy number of crushed rock layer is larger [19]. The Boussinesq approximation is employed as long as the thermal dispersion effect in the crushed rock highway embankment is small enough and the pore air density gradient is very small compared to the relevant air density [19].…”

Section: Introductionmentioning

confidence: 99%

“…Usually, it is assumed that local thermal equilibrium exists between the earth fill or crushed rock and the air and that Darcy's law can be satisfied approximately as long as the Prandtl-Darcy number of crushed rock layer is larger [19]. The Boussinesq approximation is employed as long as the thermal dispersion effect in the crushed rock highway embankment is small enough and the pore air density gradient is very small compared to the relevant air density [19]. The moisture content in the crushed rock layer is about zero and the moisture in the soil matrix is treated as immobile [12].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Crushed Rock Layer Width on Natural Convection Cooling of Highway Embankment in Permafrost Regions

Yang

Sun

Wang

et al. 2012

AMM

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For the construction of the proposed Qinghai-Tibet Express Highway in permafrost regions, it will be necessary to use the new technique of cooling the ground temperature by the coarsely crushed rock layer with a low fines content. The heat convection governing equations based on airflow function in variable permeability porous crushed rock layer are derived. Comparison of the cooling capability of winter-time natural convection in the crushed rock highway embankments with various widths of crushed rock layer and an air-permeable side slope surface were studied using a finite element method. The result indicates that the cooling capability of natural convection within the crushed rock highway embankment with a crushed rock layer width of 12 m is stronger than that with a crushed rock layer width of 10 m. Under the same temperature and pressure boundaries, the storage of cold energy in the foundation soils below the wider crushed rock highway embankment due to natural convective heat transfer is larger than that below the narrower one.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Crushed Rock Layer Width on Natural Convection Cooling of Highway Embankment in Permafrost Regions

Yang

Sun

Wang

et al. 2012

AMM

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“…The loading top plate was made out of steel plate with a thickness of 28 mm welded to the square steel column with dimensions of 20×20 cm. Under the hypothesis of uniform distribution of pore space in the crushed rock sample, the porosity n of crushed rock layer may be defined as [21] V…”

Section: Introductionmentioning

confidence: 99%

Laboratory Experiment on Porosity Variation of Crushed Rock Layer under Vibrating Load

Sun

Yang

Bai

et al. 2010

AMM

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Under the background of the express-reconstruction of the Qinghai-Tibet Highway being proposed, it will be necessary to employ the special technique of cooling the ground temperature by the crushed rock embankment in order to protect from damage to highway embankment due to thaw settlement. Under vibrating load, the porosity variation of crushed rock layer may weaken the cooling effect of buoyancy-driven natural convection of the pore air in the crushed rock layer of the highway embankment, thus resulting in instability and failure of the road embankment structure. Under these conditions, the effect of vibrating load on the porosity of the crushed rock layer must be studied both theorectically and experimentally. In this work, laboratory experiment on the porosity variation of the crushed rock layer under vertically vibrating loads is developed based on the water flooding approach and the experimental method is introduced. The test results indicate that due to the vibrating load the crushed rock layer causes the compacting effect and the shapes of crushed rock grain tend to be non- angular.

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