水泥固化体淋滤液对GCL防渗性能的影响
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摘要
水泥固化/稳定化是危险废弃物处理的经济、高效方法,然而,水泥固化体的淋滤液中含有大量Ca~(2+),其长期渗透有可能导致填埋场底部土工合成黏土衬垫(geosyntheticclayliner,GCL)的防渗性能下降,从而引发二次污染。使用柔性壁渗透仪,测定有效应力和水泥固化体淋滤液共同作用下GCL的渗透系数,探讨了淋滤液浓度以及不同有效应力对GCL渗透系数的影响。试验结果表明:当有效应力为24kPa时,水泥固化体淋滤液的持续渗透会使GCL的渗透系数增大179～721倍,淋滤液中Ca~(2+)浓度越高,GCL渗透系数增大的幅度越大。通过增加有效应力,可以降低固化体淋滤液对GCL防渗性能所造成的负面影响,当有效应力增大至438 kPa时,固化体淋滤液对GCL防渗性能所造成的负面影响全部被抵消。
Cement solidification/stabilization is an economical and efficient method to dispose hazardous waste.However,theleachates from portland cement stabilization/solidification product landfills generally contain high concentration of Ca~(2+),which may has detrimental effects on the long-term hydraulic performance of geosynthetic clay liners(GCLs),and cause a secondary pollution.Therefore,hydraulic conductivity tests are performed on the GCLs using two leachates and five effective stresses.The test results show that permeation of leachates results in an increase in the hydraulic conductivity of 179 to 721 times under the effective stress of 24 kPa,and the higher the concentration of Ca~(2+) in the leachates,the higher the hydraulic conductivities of the GCLs.The negative effects of the leachates can be offset by the effective stress applied on the GCLs.For example,when the effective stress increases to 438 kPa,the hydraulic conductivities to the leachates are comparable to those obtained for the controlled specimens(permeated with tap water),and the detrimental effects resulting from the permeation of the leachates are balanced completely by the effective stress.
Cement solidification/stabilization is an economical and efficient method to dispose hazardous waste.However,theleachates from portland cement stabilization/solidification product landfills generally contain high concentration of Ca~(2+),which may has detrimental effects on the long-term hydraulic performance of geosynthetic clay liners(GCLs),and cause a secondary pollution.Therefore,hydraulic conductivity tests are performed on the GCLs using two leachates and five effective stresses.The test results show that permeation of leachates results in an increase in the hydraulic conductivity of 179 to 721 times under the effective stress of 24 kPa,and the higher the concentration of Ca~(2+) in the leachates,the higher the hydraulic conductivities of the GCLs.The negative effects of the leachates can be offset by the effective stress applied on the GCLs.For example,when the effective stress increases to 438 kPa,the hydraulic conductivities to the leachates are comparable to those obtained for the controlled specimens(permeated with tap water),and the detrimental effects resulting from the permeation of the leachates are balanced completely by the effective stress.
引文
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[21]LO I M,TANG C,LI X,POON C.Leaching and microstructural analysis of cement-based solidified wastes[J].Environmental Science&Technology,2000,34(23):5038-5042.
[22]CATALAN L J J,MERLIèRE E,CHEZICK C.Study of the physical and chemical mechanisms influencing the long-term environmental stability of natrojarosite waste treated by stabilization/solidification[J].Journal of Hazardous Materials,2002,94(1):63-88.
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[25]许四法,吴雪辉,胡琦,等.Ca2+浓度对膨润土掺砂混合土渗透性能的影响[J].岩土工程学报,2017,39(6):1145-1150.(XU Si-fa,WU Xue-hui,HU Qi,et al.Influence of Ca2+concentration on hydraulic properties of bentonite-sand mixtures[J].Chinese Journal of Geotechnical Engineering,2017,39(6):1145-1150.(in Chinese))
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[27]朱伟,徐浩青,王升位,等.CaCl2溶液对不同黏土基防渗墙渗透性的影响[J].岩土力学,2016,37(5):1224-1231.(ZHU Wei,XU Hao-qing,WANG Sheng-wei,et al.Influence of Ca Cl2 solution on the permeability of different clay-based cutoff walls[J].Rock and Soil Mechanics,2016,37(5):1224-1231.(in Chinese))
[28]PETROV R J,ROWE R K.Geosynthetic clay liner(GCL)-chemical compatibility by hydraulic conductivity testing and factors impacting its performance[J].Canadian Geotechnical Journal,1997,34(6):863-885.
[29]THIEL R S,CRILEY K.Hydraulic conductivity of partially prehydrated GCLs under high effective confining stresses for three real leachates[C]//Alshawabkeh A.Waste Containment and Remediation.GSP 142.Austin,2005:1-11.
[30]KOLSTAD D,BENSON C,EDIL T.Hydraulic conductivity and swell of nonprehydrated geosynthetic clay liners permeated with multispecies inorganic solutions[J].Journal of Geotechnical and Geoenvironmental Engineering,2004,130(12):1236-1249.
[31]EGLOFFSTEIN T A.Natural bentonites-influence of the ion exchange and partial desiccation on permeability and self-healing capacity of bentonites used in GCLs[J].Geotextiles and Geomembranes,2001,19(7):427-444.
[2]唐强,潘玲玲,高玉峰,等.飞灰固化工程材料在碳化条件下的强度及环境特性研究[J].岩土工程学报,2018,40(4):645-654.(TANG Qiang,PAN Ling-ling,GAOYu-feng,et al.Strength and environmental behaviors of solidified fly ash under carbonation effect[J].Chinese Journal of Geotechnical Engineering,2018,40(4):645-654.(in Chinese))
[3]林伟岸,詹良通,陈云敏,等.GCL/GM界面膨润土挤出机理研究[J].岩土工程学报,2010,32(6):832-837.(LINWei-an,ZHAN Liang-tong,CHEN Yun-min,et al.Mechanism of bentonite extrusion of GCL/GM interface[J].Chinese Journal of Geotechnical Engineering,2010,32(6):832-837.(in Chinese))
[4]李志斌,徐超.竖向应力作用下GCL的膨胀特性和渗透性能[J].岩土工程学报,2007,29(12):1876-1880.(LIZhi-bin,XU Chao.Swelling characteristics and hydraulic properties of GCLs under vertical stress[J].Chinese Journal of Geotechnical Engineering,2007,29(12):1876-1880.(in Chinese))
[5]BOUAZZA A.Geosynthetic clay liner[J].Geotextiles and Geomembranes,2002,20(1):3-17.
[6]SHACKELFORD C D,BENSON C H,KATUMI T,et al.Evaluating the hydraulic conductivity of GCLs permeated with non-standard liquids[J].Geotextiles and Geomembranes,2000,18(2/3/4):133-161.
[7]RUBL J L,DANIEL D E.Geosynthetic clay liners permeated with chemical solutions and leachates[J].Journal of Geotechnical and Geoenvironmental Engineering,1997,123(4):369-381.
[8]BRADSHAW S L,BENSON C H,RAUEN T L.Hydraulic conductivity of geosynthetic clay liners to recirculated municipal solid waste leachates[J].Journal of Geotechnical and Geoenvironmental Engineering,2016,142(2):4015074.
[9]SHAN H Y,LAI Y J.Effect of hydrating liquid on the hydraulic properties of geosynthetic clay liners[J].Geotextiles and Geomembranes,2002,20(1):19-38.
[10]GUYONNET D,TOUZE-FOLTZ N,NOROTTE V,et al.Performance-based indicators for controlling geosynthetic clay liners in landfill applications[J].Geotextiles and Geomembranes,2009,27(5):321-331.
[11]LANGE K,ROWE R K,JAMIESON H.The potential role of geosynthetic clay liners in mine water treatment systems[J].Geotextiles and Geomembranes,2010,28(2):199-205.
[12]LANGE K,ROWE R K,JAMIESON H.Metal retention in geosynthetic clay liners following permeation by different mining solutions[J].Geosynthetics International,2007,14(3):178-187.
[13]SHACKELFORD C D,SEVICK G W,EYKHOLT G R.Hydraulic conductivity of geosynthetic clay liners to tailings impoundment solutions[J].Geotextiles and Geomembranes,2010,28(2):149-162.
[14]NAKA A,KATSUMI T,FLORES G,INUI T,et al.Evaluation of mineral barriers against acid rock drainage[J].Geotechnical Engineering Journal of the SEAGS&AGSSEA,2012,43(3):35-42.
[15]CHEN J N,BENSON C H,EDIL T B.Hydraulic conductivity of geosynthetic clay liners with sodium bentonite to coal combustion product leachates[J].Journal of Geotechnical and Geoenvironmental Engineering,2018,144(3):4018008.
[16]SETZ M C,TIAN K,BENSON C H,et al.Effect of ammonium on the hydraulic conductivity of geosynthetic clay liners[J].Geotextiles and Geomembranes,2017,45(6):665-673.
[17]LIU Y,BOUAZZA A,GATES W P,et al.Hydraulic performance of geosynthetic clay liners to sulfuric acid solutions[J].Geotextiles and Geomembranes,2015,43(1):14-23.
[18]PETROV R J,ROWE R K,QUIGLEY R M.Selected factors influencing GCL hydraulic conductivity[J].Journal of Geotechnical and Geoenvironmental Engineering,1997,123(8):683-695.
[19]KANG J B,SHACKELFORD C D.Consolidation of a geosynthetic clay liner under isotropic states of stress[J].Journal of Geotechnical and Geoenvironmental Engineering,2009,136(1):253-259.
[20]DANIEL D E,BOWDERS J J,GILBERT R B.Laboratory hydraulic conductivity testing of GCLs in flexible-wall permeameters[M]//Testing and Acceptance Criteria for Geosynthetic Clay Liners.STP 1308.West Conshohocken:ASTM,1997:208-226.
[21]LO I M,TANG C,LI X,POON C.Leaching and microstructural analysis of cement-based solidified wastes[J].Environmental Science&Technology,2000,34(23):5038-5042.
[22]CATALAN L J J,MERLIèRE E,CHEZICK C.Study of the physical and chemical mechanisms influencing the long-term environmental stability of natrojarosite waste treated by stabilization/solidification[J].Journal of Hazardous Materials,2002,94(1):63-88.
[23]ASTM D 6766-12 Standard test method for evaluation of hydraulic properties of geosynthetic clay liners permeated with potentially incompatible aqueous solutions[S].2012.
[24]王宝,董兴玲.不同有效应力下矿山渗滤液对土工合成黏土衬垫渗透特性影响的试验研究[J].岩土力学,2017,38(5):1350-1358.(WANG Bao,DONG Xing-ling.Hydraulic conductivity of mine leachate through geosynthetic clay liners under different effective stresses[J].Rock and Soil Mechanics,2017,38(5):1350-1358.(in Chinese))
[25]许四法,吴雪辉,胡琦,等.Ca2+浓度对膨润土掺砂混合土渗透性能的影响[J].岩土工程学报,2017,39(6):1145-1150.(XU Si-fa,WU Xue-hui,HU Qi,et al.Influence of Ca2+concentration on hydraulic properties of bentonite-sand mixtures[J].Chinese Journal of Geotechnical Engineering,2017,39(6):1145-1150.(in Chinese))
[26]杨玉玲,杜延军,范日东,等.膨润土系隔离墙材料渗透特性研究综述[J].岩土工程学报,2015,37(增刊2):210-216.(YANG Yu-ling,DU Yan-jun,FAN Ri-dong,et al.Advances in permeability for bentonite-based hydraulic containment barriers[J].Chinese Journal of Geotechnical Engineering,2015,37(S2):210-216.(in Chinese))
[27]朱伟,徐浩青,王升位,等.CaCl2溶液对不同黏土基防渗墙渗透性的影响[J].岩土力学,2016,37(5):1224-1231.(ZHU Wei,XU Hao-qing,WANG Sheng-wei,et al.Influence of Ca Cl2 solution on the permeability of different clay-based cutoff walls[J].Rock and Soil Mechanics,2016,37(5):1224-1231.(in Chinese))
[28]PETROV R J,ROWE R K.Geosynthetic clay liner(GCL)-chemical compatibility by hydraulic conductivity testing and factors impacting its performance[J].Canadian Geotechnical Journal,1997,34(6):863-885.
[29]THIEL R S,CRILEY K.Hydraulic conductivity of partially prehydrated GCLs under high effective confining stresses for three real leachates[C]//Alshawabkeh A.Waste Containment and Remediation.GSP 142.Austin,2005:1-11.
[30]KOLSTAD D,BENSON C,EDIL T.Hydraulic conductivity and swell of nonprehydrated geosynthetic clay liners permeated with multispecies inorganic solutions[J].Journal of Geotechnical and Geoenvironmental Engineering,2004,130(12):1236-1249.
[31]EGLOFFSTEIN T A.Natural bentonites-influence of the ion exchange and partial desiccation on permeability and self-healing capacity of bentonites used in GCLs[J].Geotextiles and Geomembranes,2001,19(7):427-444.