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学者姓名：冯嵩
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Abstract ：
Relying solely on soil properties may not fully ensure the performance of capillary barrier covers at limiting landfill gas (LFG) emissions. This study proposed to install passive gas collection pipes in the coarse-grained soil layers of capillary barrier covers to enhance their performance at limiting LFG emissions. First, the LFG generation rate of municipal solid waste and its influencing factors were analyzed based on empirical formulas. This information provided necessary bottom boundary conditions for the analyses of LFG transport through capillary barrier covers with passive gas collection pipes (CBCPPs). Then, numerical simulations were conducted to investigate the LFG transport properties through CBCPPs and reveal relevant influencing factors. Finally, practical suggestions were proposed to optimize the design of CBCPPs. The results indicated that the maximum whole-site LFG generation rate occurred at the end of landfilling operation. The gas collection efficiency (E) of CBCPPs was mainly controlled by the ratio of the intrinsic permeability between the coarse- and fine-grained soil (K2/K1) and the laying spacing between gas collection pipes (D). E increased as K2/K1 increased but decreased as D increased. An empirical expression for estimating E based on K2/K1 and D was proposed. In practice, CBCPPs were supposed to be constructed once the landfilling operation finished. It is best to select the fine- and coarse-grained soils with K2/K1 exceeding 10,000 to construct CBCPPs. © 2024 Elsevier B.V.
Keyword ：
Biogas Biogas Gas emissions Gas emissions Land fill Land fill Municipal solid waste Municipal solid waste Numerical models Numerical models Optimal systems Optimal systems Renewable energy Renewable energy Soils Soils
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| GB/T 7714 | Li, Guangyao , Liu, Sida , Jiao, Weiguo et al. Numerical investigation and optimal design of capillary barrier cover with passive gas collection pipes on the performance at limiting landfill gas emissions [J]. | Science of the Total Environment , 2024 , 927 . |
| MLA | Li, Guangyao et al. "Numerical investigation and optimal design of capillary barrier cover with passive gas collection pipes on the performance at limiting landfill gas emissions" . | Science of the Total Environment 927 (2024) . |
| APA | Li, Guangyao , Liu, Sida , Jiao, Weiguo , Feng, Song , Zhan, Liangtong , Chen, Yunmin . Numerical investigation and optimal design of capillary barrier cover with passive gas collection pipes on the performance at limiting landfill gas emissions . | Science of the Total Environment , 2024 , 927 . |
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The gas diffusion (Dg) and permeability (Kg) coefficients are the two important parameters for the study on gas transport in unsaturated soils. In the present study, the theory of calculating Dg and Kg for unsaturated soils under steady state is derived. Dg and Kg of unsaturated soils are determined based on the relationship between tracer gas concentration (C) and gas flow rate (q1) and that between pressure gradient (p) and gas flow rate (q2), respectively. A device for in-situ measurement of Dg and Kg in unsaturated soils is designed and developed. The soil column tests are conducted to measure Dg and Kg of unsaturated soils with different water contents. Thereafter, the element tests and numerical simulation analysis are used to verify the effectiveness of the new method and device. It is found that Dg and Kg obtained by the new method are in good agreement with the results of the element tests and numerical simulations. The results of the sensitivity analysis show that the measurement accuracy of Dg reduces as the soil water content decreases, while the measurement accuracy of Kg is independent of water content of soil. The measurement accuracies of both Dg and Kg decrease with the increase of the radius of the aeration bulb, but the measurement of Kg is more sensitive to the change of the radius. The measurement accuracy of Kg is about 55% of the true value, when the radius of the aeration bulb is 0.05 m. The soil anisotropy reduces the measurement accuracy; when the values of Dgv/Dgh and Kgv/Kgh is 0.1, the measurement accuracies of Dg and Kg can still reach more than 40%. © 2024 Chinese Society of Civil Engineering. All rights reserved.
Keyword ：
Diffusion in gases Diffusion in gases Flow of gases Flow of gases Gases Gases Gas permeability Gas permeability Numerical methods Numerical methods Numerical models Numerical models Sensitivity analysis Sensitivity analysis Soil moisture Soil moisture Soil testing Soil testing
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| GB/T 7714 | Liu, Hongwei , Wang, Mengqi , Zhan, Liangtong et al. Method and apparatus for measuring in-situ gas diffusion coefficient and permeability coefficient of unsaturated soils [J]. | Chinese Journal of Geotechnical Engineering , 2024 , 46 (5) : 948-958 . |
| MLA | Liu, Hongwei et al. "Method and apparatus for measuring in-situ gas diffusion coefficient and permeability coefficient of unsaturated soils" . | Chinese Journal of Geotechnical Engineering 46 . 5 (2024) : 948-958 . |
| APA | Liu, Hongwei , Wang, Mengqi , Zhan, Liangtong , Feng, Song , Wu, Tao . Method and apparatus for measuring in-situ gas diffusion coefficient and permeability coefficient of unsaturated soils . | Chinese Journal of Geotechnical Engineering , 2024 , 46 (5) , 948-958 . |
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Soil column tests were conducted to investigate methane oxidation efficiency in three configurations of earthen landfill cover under two drying stages separated by an applied rainfall, including the monolithic evapotranspiration (ET) cover, the cover with capillary barrier effect (CCBE) and the three-layer cover. Comprehensive measurements were also documented for water–gas response in soil for analyzing the experimental outcomes. The maximum methane oxidation efficiency of three-layer cover, monolithic ET cover, and CCBE were about 71 %, 62 % and 58 %, respectively. This was because the three-layer cover had the largest oxygen (O2) concentration in soil above depth of 400 mm, where methane oxidation mainly occurred. This was due to the good airtightness of the bottom hydraulic barrier layer, which led to the lowest air pressure above depth of 400 mm, thereby promoting the entry of atmospheric O2 into the soil. The monolithic ET cover generally had a larger methane oxidation efficiency than CCBE during the first drying stage by up to 12 %, while the trend reversed overall during the second drying stage, likely due to the enhanced air-tightness of CCBE caused by higher soil water content after rainfall induced by the capillary barrier effects. The methane oxidation efficiency for each landfill cover became lower by up to 30 % during the second drying stage than that during the first drying stage, owing to the higher water content during the second drying stage after rainfall, leading to a larger gas pressure and hence a lower O2 concentration at shallow soil. © 2024 Elsevier Ltd
Keyword ：
Atmospheric pressure Atmospheric pressure Capillarity Capillarity Land fill Land fill Soil testing Soil testing Water content Water content
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| GB/T 7714 | Liu, H.W. , Huang, Y. , Feng, S. et al. Experimental study of methane oxidation efficiency in three configurations of earthen landfill cover through soil column test [J]. | Waste Management , 2024 , 190 : 370-381 . |
| MLA | Liu, H.W. et al. "Experimental study of methane oxidation efficiency in three configurations of earthen landfill cover through soil column test" . | Waste Management 190 (2024) : 370-381 . |
| APA | Liu, H.W. , Huang, Y. , Feng, S. , You, S.Q. , Hong, Y. , Shen, L.D. . Experimental study of methane oxidation efficiency in three configurations of earthen landfill cover through soil column test . | Waste Management , 2024 , 190 , 370-381 . |
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Wetting-drying cycles have a significant impact on the gas diffusion coefficient (Dp) and gas permeability (ka) of unsaturated soils. The soil volume change during wetting-drying cycles limits the application of the traditional rigid-wall device for measuring ka and Dp, due to the gas preferential flow along the interface between soil and the rigid-wall container. Although flexible-wall devices for measuring ka are available, no such device exists for measuring Dp. Thus, the effects of wetting-drying cycles on Dp remain unclear, particularly for fine-grained soil. The present study developed a flexible-wall device to investigate the effects of a wetting-drying cycle on the Dp and ka of unsaturated soils. Both the flexible- and rigid-wall devices were adopted to measure ka and Dp of three soil types, including fine sand, silt and kaolin. The rigid-wall device could overestimate ka by up to approximately one order of magnitude, whereas it overestimated Dp by approximately 2-3 times. Regardless of ka and Dp, the difference in measurements between the rigid- and flexible-wall devices became more significant at a lower water content and along the drying path because of the gas preferential flow caused by soil shrinkage in the rigid-wall device. Accordingly, the kaolin exhibited the largest difference in ka and Dp as measured by the flexible- and rigid-wall devices because it had the largest clay minerals and the finest particle size, resulting in the largest volume shrinkage. The ka and Dp measured by the flexible-wall device along the drying path were generally larger than those along the wetting path, probably because of entrapped gas in the soil caused by water spray during wetting. © 2024 American Society of Civil Engineers.
Keyword ：
Gas transport Gas transport Measurement device Measurement device Soil texture Soil texture Soil volume change Soil volume change Wetting-drying cycles Wetting-drying cycles
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| GB/T 7714 | Liu, Y. , Feng, S. , Liu, H. . Measurements of Drying and Wetting Gas Diffusion Coefficients and Gas Permeability of Unsaturated Soils Using a New Flexible-Wall Device [J]. | Journal of Geotechnical and Geoenvironmental Engineering , 2024 , 150 (11) . |
| MLA | Liu, Y. et al. "Measurements of Drying and Wetting Gas Diffusion Coefficients and Gas Permeability of Unsaturated Soils Using a New Flexible-Wall Device" . | Journal of Geotechnical and Geoenvironmental Engineering 150 . 11 (2024) . |
| APA | Liu, Y. , Feng, S. , Liu, H. . Measurements of Drying and Wetting Gas Diffusion Coefficients and Gas Permeability of Unsaturated Soils Using a New Flexible-Wall Device . | Journal of Geotechnical and Geoenvironmental Engineering , 2024 , 150 (11) . |
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气体扩散系数D_g和渗透系数K_g是研究非饱和土中气体运移的两个重要参数。推导了稳态条件下,非饱和土中气体运移参数的计算理论。该理论基于示踪气体浓度C与气体流量q_1之间及压力梯度P与气体流量q_2之间的变化规律,分别确定非饱和土的D_g,K_g。依据推导的理论公式,设计并研制了一种原位测量非饱和土的D_g,K_g的装置。开展土柱试验,利用新装置测量非饱和土的D_g,K_g,并采用单元试验和数值模拟验证新方法和装置的有效性。研究表明新方法测量的非饱和土的D_g,K_g与单元试验及数值模拟结果吻合良好。基于数值模拟开展的敏感性分析结果揭示:D_g测量准确度随土体的质量含水率w减少而降低,而K_g的测量准确度受含水量的影响不显著;非饱和土的D_g,K_g的测量准确度均随着注气球半径增加而降低,但是注气球半径对K_g的测量准确度的影响更为显著,当注气球半径增加到0.05 m时,其准确度约为55%;土体各向异性降低测量准确度,当竖向与水平向的气体运移参数的比值D_(gv)/D_(gh)和K_(gv)/K_(gh)均为0.1时,D_g,K_g的测量准确度仍可达到40%以上。
Keyword ：
原位测量装置 原位测量装置 数值模拟 数值模拟 气体扩散系数 气体扩散系数 气体渗透系数 气体渗透系数 非饱和土 非饱和土
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| GB/T 7714 | 刘红位 , 王孟奇 , 詹良通 et al. 一种原位测量非饱和土的气体扩散系数和渗透系数的方法与装置 [J]. | 岩土工程学报 , 2024 , 46 (05) : 948-958 . |
| MLA | 刘红位 et al. "一种原位测量非饱和土的气体扩散系数和渗透系数的方法与装置" . | 岩土工程学报 46 . 05 (2024) : 948-958 . |
| APA | 刘红位 , 王孟奇 , 詹良通 , 冯嵩 , 吴涛 . 一种原位测量非饱和土的气体扩散系数和渗透系数的方法与装置 . | 岩土工程学报 , 2024 , 46 (05) , 948-958 . |
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Phenolic compounds are prevalent organic contaminants in aquatic and soil environments. In order to address the issue of phenolic wastewater treatment, bentonite can be utilized as an effective adsorbent through organic modification. The present study focuses on using sodium bentonite, which was modified with cetyltrimethylammonium bromide (CTMAB), to remove phenol from an aqueous solution. The influence of various factors such as adsorption time, initial phenol concentration, and CTMAB-bentonite dosage on phenol adsorption was thoroughly investigated. In addition, the microstructural changes during the adsorption process, adsorption kinetics, and adsorption isotherms of the organically modified bentonite (OMB) were analyzed. The results indicated that the adsorption equilibrium time of OMB was longer compared to sodium bentonite. The amount of phenol adsorbed by OMB was found to be positively correlated with the initial phenol concentration and CTMAB-bentonite dosage. The maximum phenol adsorption capacity and removal rate achieved were 3.00 mg/g and 43.74%, respectively. The study also revealed that a quasi-second-order kinetic model was appropriate for describing the phenol adsorption process of OMB, and the adsorption isotherm was found to conform to the Freundlich isotherm model. These findings demonstrate the potential of OMB as an efficient and effective adsorbent for phenolic wastewater treatment.
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| GB/T 7714 | He, Haijie , Chai, Kuan , Wu, Tao et al. Phenol adsorption properties and microstructural changes of organically modified bentonite [J]. | ENVIRONMENTAL GEOTECHNICS , 2023 . |
| MLA | He, Haijie et al. "Phenol adsorption properties and microstructural changes of organically modified bentonite" . | ENVIRONMENTAL GEOTECHNICS (2023) . |
| APA | He, Haijie , Chai, Kuan , Wu, Tao , Qiu, Zhanhong , Feng, Song , Wang, Shifang et al. Phenol adsorption properties and microstructural changes of organically modified bentonite . | ENVIRONMENTAL GEOTECHNICS , 2023 . |
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Vegetation has been found to improve the hydrological performance of landfill cover. However, existing studies ignore effects of hydrogen sulphide (H2S), which is a toxic odour generated from municipal solid wastes. H2S is a potential signalling molecule in regulating plant-stomata aperture, but how the plant-H2S interaction affects the water-gas transport in soil remains unknown. This study aimed to investigate effects of H2S on Bermuda grass growth and its influence on water-gas transport in unsaturated soils. Soil columns, with and without vegetation, were prepared and fumigated with different H2S concentrations. These columns were subjected to controlled drought and rainfall sequentially. The results showed that grass leaves almost wilted without H2S fumigation due to the Pythium diseases caused by antecedent waterlogged conditions. In contrast, H2S fumigation promoted grass growth because of the fungicidal effects of H2S. Upon drought, H2S fumigation caused stomata closure, which resulted in a lower matric suction in the vegetated soil than that without H2S fumigation. Accordingly, H2S concentration reduced because of oxidation by metal oxides in soil. Upon subsequent rainfall, more infiltration but lower matric suction was observed in vegetated soils than that in bare case, whereas H2S concentration decreased continuously due to gas dissolution in the pore water. Direct application of laboratory findings herein to field cases should be used with cautions, because the applied continuous lightening and low evapotranspiration rate of the soil column tests may not be representative to field conditions.
Keyword ：
gas gas landfills landfills unsaturated soil unsaturated soil vegetation vegetation water flow water flow
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| GB/T 7714 | Feng, Song , Leung, Anthony Kwan , Zhan, Liang Tong et al. Effects of hydrogen sulphide on grass traits and water-gas transport in grass-planted unsaturated soil [J]. | GEOTECHNIQUE , 2023 , 74 (12) : 1404-1420 . |
| MLA | Feng, Song et al. "Effects of hydrogen sulphide on grass traits and water-gas transport in grass-planted unsaturated soil" . | GEOTECHNIQUE 74 . 12 (2023) : 1404-1420 . |
| APA | Feng, Song , Leung, Anthony Kwan , Zhan, Liang Tong , Liu, Hong Wei , Wang, Min , Guo, Xing Kai . Effects of hydrogen sulphide on grass traits and water-gas transport in grass-planted unsaturated soil . | GEOTECHNIQUE , 2023 , 74 (12) , 1404-1420 . |
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Biochemical decomposition of high kitchen wastes in landfills in China results in (i) a high content of vapor in landfill gas (LFG) and (ii) a noticeable temperature gradient across the earthen final cover (EFC). Yet, it is unclear how vapor and temperature gradients affect moisture and gas transport through EFC and microbial aerobic methane oxidation (MAMO). A theoretical model of moisture-gas-heat reactive transport considering MAMO and effects of vapor flow and temperature gradients was developed, and a series of parametric studies were included. The model was verified by published test results. The parametric simulation results show that vapor from landfill wastes can replenish water to EFCs in dry seasons, which results in (i) the relief of water shortage of vegetation and MAMO and (ii) LFG emission reduction. Effects of vapor inflow become more significant under larger temperature gradient. In cold seasons, temperature gra-dients can promote MAMO to reduce methane emissions, and enhance evaporation to reduce percolation. When evaporation rate at the surface exceeds 30 times vapor influx, vapor inflow has negligible effects on moisture and gas transport in EFCs. Neglecting effects of vapor and temperature gradient can lead to misjudgments on anti-seepage performance and methane emission reduction performance of EFCs.(c) 2022 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society. This is an open access article under the CC BY -NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Keyword ：
Earthen landfill cover Earthen landfill cover Methane oxidation Methane oxidation Moisture-heat-gas transport Moisture-heat-gas transport Temperature gradient Temperature gradient Vapor Vapor
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| GB/T 7714 | Wu, Tao , Zhan, Liangtong , Feng, Song et al. Numerical analysis of moisture and gas transport in earthen final covers considering effects of vapor and temperature gradient [J]. | SOILS AND FOUNDATIONS , 2023 , 63 (1) . |
| MLA | Wu, Tao et al. "Numerical analysis of moisture and gas transport in earthen final covers considering effects of vapor and temperature gradient" . | SOILS AND FOUNDATIONS 63 . 1 (2023) . |
| APA | Wu, Tao , Zhan, Liangtong , Feng, Song , Chen, Ping . Numerical analysis of moisture and gas transport in earthen final covers considering effects of vapor and temperature gradient . | SOILS AND FOUNDATIONS , 2023 , 63 (1) . |
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This study presents an analytical solution for coupled water-gas transport in a landfill cover system considering four different root architectures (i.e., uniform, triangular, exponential and parabolic architectures), which can consider transient diffusive-advective transport of gas under steady-state water distributions in different con-dition (e.g., rainfall stage and evaporation stage). The proposed solution is verified against an existing analytical solution, validated against an experiment, and compared with a numerical solution. Using the verified analytical solution, simulations were conducted on the coupled water-gas transport. The results show that ignoring water transport can lead to significant error in gas transport results under various conditions (e.g., the methane flux is underestimated by 45% due to ignoring water transport, when the desaturation coefficient alpha is 0.1 m1). The parametric study results indicate that triangular and exponential root architectures have greater effect on water-gas transport (e.g., pore-water pressure, gas emission fluxes) compared with the uniform and parabolic root architectures; vegetation has a significant impact on the water-gas transport, especially in dry conditions (e. g., the gas emission flux through vegetated cover is about 26.3% lower than that through the bare cover); the rainfall intensity and volumetric water content at the bottom boundary have significant effect on water-gas transport in the cover. The proposed analytical solution can be used to aid the design of vegetated soil cover system and the verification of other more complex models
Keyword ：
Analytical solution Analytical solution Coupled water-gas transport Coupled water-gas transport Landfill cover system Landfill cover system Root architecture Root architecture
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| GB/T 7714 | Min, Ming , Pu, He-Fu , Feng, Song et al. Analytical solution for coupled water-gas transport in unsaturated landfill cover system with different root architectures br [J]. | COMPUTERS AND GEOTECHNICS , 2023 , 154 . |
| MLA | Min, Ming et al. "Analytical solution for coupled water-gas transport in unsaturated landfill cover system with different root architectures br" . | COMPUTERS AND GEOTECHNICS 154 (2023) . |
| APA | Min, Ming , Pu, He-Fu , Feng, Song , Qiu, Jin-Wei , Wen, Xiao-Jun . Analytical solution for coupled water-gas transport in unsaturated landfill cover system with different root architectures br . | COMPUTERS AND GEOTECHNICS , 2023 , 154 . |
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A new method and instrument were developed for in situ measurement of the gas diffusion coefficient (D-g) and gas coefficient of permeability (k(g)) of unsaturated soil. Air containing tracer gas of volumetric concentration of 5%-10% was continuously pumped into a point source at a constant flux rate (q(0)) until approaching steady state. Then, the pseudo-steady-state tracer gas concentration (C-r0) and gas gauge pressure (Delta Pr0) were recorded at a distance (r0) away from the point source. The Dg and kg were determined through the Cr0-q0 and Delta Pr0-q0 relationships, respectively. Soil column tests (silty sand) and field tests (sandy lean clay) were conducted to validate the new method. The in situ measured Dg and kg were comparable with those of undisturbed specimens measured by a two-chamber apparatus. The in situ measurement of Dg and kg ranged from 2x10-8 m2 s-1 to 4x10-6 m2 s-1 and 1.9x10-8 ms-1 to 3.9x10-7 ms-1, respectively. The measurement accuracy increased at deeper depth, due to reduced boundary effect at soil surface. The measurement of in situ Dg was more susceptible to the boundary effects than that of kg at shallower depth (i.e., 20 cm deep) in general. The field test results showed that the ratio of in situ Dg (or kg) to that measured by the element tests was generally between 1.2 and 3.3 at or below depth of 0.30 m, due to the in situ heterogeneity of soil.
Keyword ：
Gas coefficient of permeability Gas coefficient of permeability Gas diffusion coefficient Gas diffusion coefficient In situ measurement In situ measurement Unsaturated soil Unsaturated soil
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| GB/T 7714 | Feng, S. , Sun, J. X. , Zhan, L. T. et al. A New Method and Instrument for Measuring In Situ Gas Diffusion Coefficient and Gas Coefficient of Permeability of Unsaturated Soil [J]. | JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING , 2023 , 149 (7) . |
| MLA | Feng, S. et al. "A New Method and Instrument for Measuring In Situ Gas Diffusion Coefficient and Gas Coefficient of Permeability of Unsaturated Soil" . | JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING 149 . 7 (2023) . |
| APA | Feng, S. , Sun, J. X. , Zhan, L. T. , Liu, H. W. . A New Method and Instrument for Measuring In Situ Gas Diffusion Coefficient and Gas Coefficient of Permeability of Unsaturated Soil . | JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING , 2023 , 149 (7) . |
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