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| Chemico-osmotic membrane behavior and diffusive properties of PAC amended bentonite/sand vertical cutoff wall backfills |
| FU Xianlei,DU Yanjun,SHEN Shengqiang,BI Yuzhang,ZHANG Run |
| (Institute of Geotechnical Engineering,Southeast University,Nanjing,Jiangsu 211189,China) |
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Abstract The membrane behavior of soil bentonite(SB) vertical cutoff wall backfills is important in evaluating the contaminant containment performance of the SB vertical cutoff walls. Lead nitrate(Pb(NO3)2) solutions with various concentrations were tested as testing liquids for a multi-stage chemico-osmotic soil column test to assess chemico-osmotic efficiency coefficients,effective diffusion coefficients and retardation factors of polyanionic cellulose(PAC) amended bentonite/sand(PSB) and unamended SB backfills. The results showed that the measured chemico-osmotic efficiency coefficients of PSB and unamended SB backfills decreased with increasing Pb(NO3)2 concentration. The measured chemico-osmotic efficiency coefficient of the backfill in the Pb(NO3)2 solutions was enhanced with PAC amendment,which was about 2–3 times of that of unamended SB backfill. The effective diffusion coefficients of PSB and unamended SB backfills increased with increasing source Pb(NO3)2 concentration,whereas the retardation factors of lead reduced with increasing Pb(NO3)2 concentration. Compared with unamended SB backfills,PSB backfills possessed lower effective diffusion coefficient and higher retardation factor at a given Pb(NO3)2 solution.
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| [1] SHARMA H D,REDDY K R. Geoenvironmental engineering:site remediation,waste containment and emerging waste management technologies[M]. New Jersey:John Wiley & Sons,Inc.,2004:331– 350.
[2] 刘松玉,詹良通,胡黎明,等. 环境岩土工程研究进展[J]. 土木工程学报,2016,49(3):6–30.(LIU Songyu,ZHAN Liangtong,HU Liming,et al. Environmental geotechnics:state of the art of theory,testing and application to practice[J]. China Civil Engineering Journal,2016,49(3):6–30.(in Chinese))
[3] YANG Y L,DU Y J,REDDY K R,et al. Phosphate-amended sand/Ca-bentonite mixtures as slurry trench wall backfills:Assessment of workability,compressibility and hydraulic conductivity[J]. Applied Clay Science,2017,142:120–127.
[4] YANG Y L,REDDY K R,DU Y J,et al. Short-term hydraulic conductivity and consolidation properties of soil-bentonite backfills exposed to CCR-impacted groundwater[J]. Journal of Geotechnical and Geoenvironmental Engineering,2018,144:04018025.
[5] YANG Y L,REDDY K R,ZHANG W J,et al. SHMP-amended ca-bentonite/sand backfill barrier for containment of lead contamination in groundwater[J]. International Journal of Environmental Research and Public Health,2020,17:370.
[6] SHEN S Q,WEI M L. Hydraulic conductivity of polymer-amended sand-bentonite backfills permeated with lead nitrate solutions[J]. Advances in Civil Engineering,2018,(1):1–12.
[7] SHACKELFORD C D,LEE J M. The destructive role of diffusion on clay membrane behavior[J]. Clays and Clay Minerals,2003,51(2):186–196.
[8] HENNING J T,EVANS J C,SHACKELFORD C D. Membrane behavior of two backfills from field-constructed soil-bentonite cutoff walls[J]. Journal of Geotechnical and Geoenvironmental Engineering,2006,132(10):1 243–1 249.
[9] YEO S S,SHACKELFORD C D,EVANS J C. Membrane behavior of model soil-bentonite backfills[J]. Journal of Geotechnical and Geoenvironmental Engineering,2005,131(4):418–429.
[10] 范日东,杜延军,刘松玉. 基于改进滤失试验的重金属污染膨润土渗透特性试验研究[J]. 岩土力学,2019,40(8):2 989–2 996.(FAN
Ridong,DU Yanjun,LIU Songyu. Modified fluid loss test to measure hydraulic conductivity of heavy metal-contaminated bentonite[J]. Rock and Soil Mechanics,2019,40(8):2 989–2 996.(in Chinese))
[11] American Society for Testing and Materials(ASTM). D1125—14 Standard test method for electrical conductivity and resistivity of water[S]. West Conshohocken:ASTM,2014.
[12] American Society for Testing and Materials(ASTM). E70—07 Method for pH of aqueous solutions with the glass electrode[S]. West Conshohocken:ASTM,2015.
[13] 张 润. 六偏磷酸钠改良膨润土系竖向工程屏障防渗吸附扩散性能研究[硕士学位论文][D]. 南京:东南大学,2018.(ZHANG Run. Hydraulic and containment performance of SHMP-amended soil- bentonite vertical cutoff wall backfills against heavy metals[M. S. Thesis][D]. Nanjing:Southeast University,2018.(in Chinese))
[14] MALUSIS M A,SHACKELFORD C D. Chemico-osmotic efficiency of a geosynthetic clay liner[J]. Journal of Geotechnical and Geoenvironmental Engineering,2002,128(2):97–106.
[15] GROENEVELT P H,ELRICK D E. Coupling phenomena in saturated homo-ionic montmorillonite: II. theoretical 1[J]. Soil Science Society of America Journal,1976,40(6):820–823.
[16] BARBOUR S L,FREDLUND D G. Mechanisms of osmotic flow and volume change in clay soils[J]. Canadian Geotechnical Journal,1989,26(4):551–562.
[17] SHACKELFORD C D. Laboratory diffusion testing for waste disposal—A review[J]. Journal of Contaminant Hydrology,1991,7(3):177–217.
[18] SHACKELFORD C D. Membrane behavior in engineered bentonite- based containment barriers:State of the art[C]// Manassero et al ed. Proceedings of the Coupled Phenomena in Environmental Geotechnics (CPEG 2013). London:Taylor & Francis Group,2013:45–60.
[19] TANG Q. Factors affecting waste leachate generation and barrier performance of landfill liners[Ph. D. Thesis][D]. Kyoto:Kyoto University,2013.
[20] 秦爱芳,傅贤雷,孙德安,等. 化–力耦合条件下膨润土的体变特性[J]. 岩石力学与工程学报,2019,38(增2):3 775–3 782.(QIN Aifang,FU Xianlei,SUN Dean,et al. Influences of chemo-mechanical coupling on the volume change behaviour of bentonite[J]. Chinese Journal of Rock Mechanics and Engineering,2019,38(Supp.2):3 775– 3 782.(in Chinese))
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