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| EFFECT OF RESIDUAL AIR ENTRAPMENT ON UNSATURATED FLOW IN POROUS MEDIA |
| CHEN Pan，WEI Changfu，WEI Houzhen，MA Tiantian |
(State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，
Chinese Academy of Sciences，Wuhan，Hubei 430071，China) |
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Abstract The sizes and connectivity of the pores in porous media such as rock and soil are randomly distributed at microscopic level. Due to this characteristics，the flow of fluids in the porous media is significantly different from the flow characteristics in the ideal single pore model. As important features of seepage，capillary hysteresis and air entrapment generally occur in the porous media experiencing cyclic change of water content. Based on the analysis of drying/wetting progress in the porous media，a theoretical model of seepage is developed，in which the effect of air entrapment is taken into account in the soil-moisture retention constitutive relation. A numerical analysis method is developed and implemented into the computer code. The model can be used to simulate the unsaturated seepage in porous media with the effect of air entrapment under arbitrary change of water content. By comparing the numerical results with measured data，it is shown that the effect of air entrapment is significant to the fluid distribution. The effects of capillary hysteresis and air entrapment should be taken into account in unsaturated seepage analysis in order to accurately predict the soil-moisture state of porous media.
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Received: 17 October 2012
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2013, Vol. 32 
