残留含气量影响的非饱和多孔介质流动过程

 多孔介质微观大小孔隙的分布及其连通具有随机性，使得流体在实际孔隙中的流动与理想单孔隙中迥异，当多孔介质中的含水量循环变化时，毛细滞回和残留含气量效应极大地影响着多孔介质的渗流过程。基于对非饱和孔隙介质干湿过程的分析，提出能够考虑残留含气量影响的土水特征关系理论模型，随后建立一个新的渗流理论模型，该模型考虑残留含气量对流动过程的影响。在此基础上，建立相应的数值分析模型，并进行程序代码的实施。建立的模型能够用于模拟任意含水量变化条件下残留含气量对多孔介质中非饱和渗流过程的影响。通过数值模拟结果与实测数据的比较，证实残留含气量效应对非饱和孔隙介质中流体分布的重要影响。为更准确地预测多孔介质中的土水状态，在非饱和渗流分析中考虑残留含气量与毛细滞回效应十分必要。

EFFECT OF RESIDUAL AIR ENTRAPMENT ON UNSATURATED FLOW IN POROUS MEDIA

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.