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6. Gas transport in partially-saturated sand packs

Author

Ghanbarian, Behzad, Hamamoto, Shoichiro, Kawamoto, Ken, Sakaki, Toshihiro, Moldrup, Per, Nishimura, Taku, and Komatsu, Toshiko

Subjects
Physics - Geophysics
Abstract

Understanding gas transport in porous media and its mechanism has broad applications in various research areas, such as carbon sequestration in deep saline aquifers and gas explorations in reservoir rocks. Gas transport is mainly controlled by pore space geometrical and morphological characteristics. In this study, we apply a physically-based model developed using concepts from percolation theory (PT) and the effective-medium approximation (EMA) to better understand diffusion and permeability of gas in packings of angular and rounded sand grains as well as glass beads. Two average sizes of grain i.e., 0.3 and 0.5 mm were used to pack sands in a column of 6 cm height and 4.9 cm diameter so that the total porosity of all packs was near 0.4. Water content, gas-filled porosity (also known as gas content), gas diffusion, and gas permeability were measured at different capillary pressures. The X-ray computed tomography method and the 3DMA-Rock software package were applied to determine the average pore coordination number z. Results showed that both saturation-dependent diffusion and permeability of gas showed almost linear behavior at higher gas-filled porosities, while deviated substantially from linear scaling at lower gas saturations. Comparing the theory with the diffusion and permeability experiments showed that the determined value of z ranged between 2.8 and 5.3, not greatly different from X-ray computed tomography results. The obtained results clearly indicate that the effect of the pore-throat size distribution on gas diffusion and permeability was minimal in these sand and glass bead packs.

Published
2018
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8. A Cost-Benefit Analysis on Construction and Demolition Waste Recycling Project in Hanoi of Vietnam: Economic, Social, and Environmental Assessment

Author

Tong, Kien T., Nguyen, Hung V., Hoang, Han N., Tran, Tan V., Ishigaki, Tomonori, Kawamoto, Ken, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Ha-Minh, Cuong, editor, Tang, Anh Minh, editor, Bui, Tinh Quoc, editor, Vu, Xuan Hong, editor, and Huynh, Dat Vu Khoa, editor

Published
2022
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9. Characterization of Water Retention and Unsaturated Hydraulic Conductivity for Recycled Road-Base Materials

Author

Ito, Ryohei, Kato, Akira, Matsuno, Akihiro, Kawamoto, Ken, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Dissanayake, Ranjith, editor, Mendis, Priyan, editor, Weerasekera, Kolita, editor, De Silva, Sudhira, editor, and Fernando, Shiromal, editor

Published
2022
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14. Effect of Moisture Content on Particle Breakage of Recycled Concrete Aggregates During Compaction

Author

Shah, Syed Kamran H., Uchimura, Taro, Kawamoto, Ken, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Hazarika, Hemanta, editor, Madabhushi, Gopal Santana Phani, editor, Yasuhara, Kazuya, editor, and Bergado, Dennes T., editor

Published
2021
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24. Linking pore network structure derived by microfocus X-ray CT to mass transport parameters in differently compacted loamy soils

Author

Baniya, Arjun, Kawamoto, Ken, Hamamoto, Shoichiro, Sakaki, Toshihiro, Saito, Takeshi, Muller, Karin, Moldrup, Per, and Komatsu, Toshiko

Subjects
Soil research, Soil structure -- Observations, Loams -- Observations, Soil permeability -- Observations, Permeability, Water wells, Hydrogeology, Local transit, Water, Seepage (Hydrology), CAT scans, Porosity, Tomography, Soils, Agricultural industry, Earth sciences
Abstract

Mass transport in soil occurs through the soil pore network, which is highly influenced by pore structural parameters such as pore-size distribution, porosity, pore tortuosity, and coordination number. In this study, we visualised the networks of meso- and macro-pores (typical pore radius r [greater than or equal to] 10 [micro]m) using micro-focus X-ray computed tomography (MFXCT) and evaluated pore structural parameters of two loamy soils from Japan and New Zealand packed at different degrees of compaction. The effect of compaction on pore structural parameters and relationships between pore structural parameters and measured mass transport parameters were examined. Results showed a clear influence of compaction on pore structural parameters, with the MFXCT-derived mean pore radii and pore tortuosities decreasing and the mean pore coordination number increasing with increasing dry bulk density. Especially, pores with r > 80 [micro]m became finer or were not well formed due to compaction. The MFXCT-derived pore structural parameters were not well correlated with the equivalent pore radii from measured water retention curves. However, volumetric surface areas and pore-network connectivity-tortuosity factors derived from MFXCT allowed a fair prediction of several important mass transport parameters such as saturated hydraulic conductivities, soil-gas diffusion coefficients, and soil-air permeabilities. Further studies are needed to link micro-pores with radii smaller than the X-ray CT resolution to meso- and macro-pores visualised by X-ray CT to improve the prediction of mass transport parameters in soil. Additional keywords: air permeability, hydraulic conductivity, microfocus X-ray computed tomography (MFXCT), pore network, soil gas diffusion coefficient., Introduction A better understanding of gas transport in soil is important to elucidate the emission of greenhouse gases (Kruse et al. 1996; Smith 2003; Kawamoto et al. 2006; Wickramarachchi et [...]

Published
2019
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31. Supplementary Data from Wnt Antagonist Gene DKK2 Is Epigenetically Silenced and Inhibits Renal Cancer Progression through Apoptotic and Cell Cycle Pathways

Author

Hirata, Hiroshi, primary, Hinoda, Yuji, primary, Nakajima, Koichi, primary, Kawamoto, Ken, primary, Kikuno, Nobuyuki, primary, Kawakami, Kazumori, primary, Yamamura, Soichiro, primary, Ueno, Koji, primary, Majid, Shahana, primary, Saini, Sharanjot, primary, Ishii, Nobuhisa, primary, and Dahiya, Rajvir, primary

Published
2023
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