The response of hydraulic conductivity to air-trapped saturation in a dissolution process of trapped-air in quasi-saturated fine sands media

CHENG Donghui; LAN Yingbo; YUAN Jing; XIANG Lin; YANG Xiaoting; QIAO Xiaoying; DENG Lin; WANG Zilin; WANG Qing

doi:10.16030/j.cnki.issn.1000-3665.202401015

2024 Vol. 51, No. 6

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CHENG Donghui, LAN Yingbo, YUAN Jing, XIANG Lin, YANG Xiaoting, QIAO Xiaoying, DENG Lin, WANG Zilin, WANG Qing. The response of hydraulic conductivity to air-trapped saturation in a dissolution process of trapped-air in quasi-saturated fine sands media[J]. Hydrogeology & Engineering Geology, 2024, 51(6): 1-7. doi: 10.16030/j.cnki.issn.1000-3665.202401015

Citation:

CHENG Donghui, LAN Yingbo, YUAN Jing, XIANG Lin, YANG Xiaoting, QIAO Xiaoying, DENG Lin, WANG Zilin, WANG Qing. The response of hydraulic conductivity to air-trapped saturation in a dissolution process of trapped-air in quasi-saturated fine sands media[J]. Hydrogeology & Engineering Geology, 2024, 51(6): 1-7. doi: 10.16030/j.cnki.issn.1000-3665.202401015

The response of hydraulic conductivity to air-trapped saturation in a dissolution process of trapped-air in quasi-saturated fine sands media

1.
School of Water and Environment, Chang’an University, Xi’an, Shaanxi　710054, China
2.
Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Chang’an University, Ministry of Education, Xi’an, Shaanxi　710054, China

Received Date: 14 January 2024

Revised Date: 08 March 2024

Publish Date: 15 November 2024

Abstract

Abstract

The hydraulic conductivity of a quasi-saturated aquifer decreases with the increase of air-trapped saturation, but it is difficult to obtain a continuous data on air-trapped saturation through the traditional displacement experiments due to limitations in experimental operations and measurement accuracy. It limits the accurate characterization of the relationship between small air-trapped saturation and the corresponding quasi-saturated hydraulic conductivity. This study designed an oxygen-trapped dissolution experiment in quasi-saturated fine sands media, instead of air-trapped, in which the soluble oxygen in water and the corresponding hydraulic conductivity can be accurately measured. Then a large amount of continuous data on air-trapped saturation and its quasi-saturated hydraulic conductivity were obtained. The experimental results show that when the air-trapped saturation is less than 5%, trapped gas may enter the ineffective pores and thus has a little effect on the value of the hydraulic conductivity. However, when the trapped gas saturation is between 5%－6%, it forms a pore throat block effect, which intensifies the influence on the hydraulic conductivity. Furthermore, a new model, i.e., van Genuchten model, was constructed to predict the quasi-saturated hydraulic conductivity. This model overcomes the shortcomings of the traditional power-law model and well characterized the feature that the small air-trapped saturation has little effect on the hydraulic conductivity. At high air-trapped saturation, the performance of van Genuchten model is comparable to the traditional model. The proposed model in this study can provide foundation for studying quasi-saturated water flow and solute transport.
- quasi-saturated fine sands media /
- air-trapped saturation /
- hydraulic conductivity /
- van Genuchten model /
- Faybishenko model

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References

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