The Impact of Capillary Trapping of Air on Satiated Hydraulic Conductivity of Sands Interpreted by X-ray Microtomography

Water

Johannes Koestel¹  Tomas Princ²  Michal Snehota²  HelenaMaria Reis Fideles² 

[1] Department of Soil and Environment, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden;Faculty of Civil Engineering, Czech Technical University in Prague, 166 29 Prague, Czech Republic;

关键词: residual saturation;    porous media;    permeability;    entrapped air;    two-phase flow;   

DOI  :  10.3390/w12020445

来源: DOAJ

【 摘 要 】

The relationship between entrapped air content and the corresponding hydraulic conductivity was investigated experimentally for two coarse sands. Two packed samples of 5 cm height were prepared for each sand. Air entrapment was created by repeated infiltration and drainage cycles. The value of K was determined using repetitive falling-head infiltration experiments, which were evaluated using Darcy’s law. The entrapped air content was determined gravimetrically after each infiltration run. The amount and distribution of air bubbles were quantified by micro-computed X-ray tomography (CT) for selected runs. The obtained relationship between entrapped air content and satiated hydraulic conductivity agreed well with Faybishenko’s (1995) formula. CT imaging revealed that entrapped air contents and bubbles sizes were increasing with the height of the sample. It was found that the size of the air bubbles and clusters increased with each experimental cycle. The relationship between initial and residual gas saturation was successfully fitted with a linear model. The combination of X-ray computed tomography and infiltration experiments has a large potential to explore the effects of entrapped air on water flow.

【 授权许可】

Unknown