黄土–碎石毛细阻滞覆盖层储水能力实测与分析
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摘要
中国西北地区气候较干旱,黄土分布广泛。就地取材采用当地的黄土作垃圾填埋场封场土质覆盖层具有技术可行性和良好的经济性。在西安江村沟垃圾填埋场建造了国内首个20m×30m大尺寸黄土–碎石毛细阻滞覆盖层现场试验基地,在基地开展了极端降雨试验。水量分配测试结果表明:总降雨量214.8 mm;坡面径流1.7 mm,占总降雨量的0.8%;土层存储(含蒸发)199.57 mm,占总降雨量的92.9%;渗漏13.53 mm,占降雨量的6.3%。基质吸力与水份运移规律分析结果表明:持续降雨条件下毛细阻滞覆盖层(900 mm)细粒土中表层土(15 cm深度以上)和底层土(85cm深度以下)的孔压(或体积含水率)均较高;底层土孔压(或体积含水率)较高是由于碎石–黄土界面间毛细阻滞效应对水份下渗的阻滞作用,这是有别于单一土层降雨入渗水份运移的显著特征。储水能力评估结果表明:极端降雨试验实测黄土–碎石毛细阻滞覆盖层有效储水量为251.95 mm。采用室内吸湿土水特征曲线评估覆盖层有效储水能力,有效储水量理论值S_(fac)为218.75 mm,实测值较理论值大15.18%,结果偏于安全。采用现场吸湿土水特征曲线评估覆盖层有效储水能力,有效储水量理论值Sfac为278.32 mm,实测值比理论值小9.47%,偏于危险。防渗设计中建议采用室内吸湿土水特征曲线。
The climate in northwest China is arid and the loess which is technically feasible and economical used for soil cover in landfills is widely distributed. At Jiangchungou Landfill, Xi'an, the first large size loess-grass capillary barrier cover 20 m×30 m is built, and the extreme rainfall experiments are carried out. The results of water distribution tests show that: with 214.8 mm rainfall, the slope runoff is 1.7 mm, accounting for 0.8% of the total rainfall, and the storage of soil(containing evaporation) is 199.57 mm, accounting for 92.9% of the total rainfall, and the leakage is 11.53 mm, accounting for 6.3% of the rainfall. The analysis of matrix suction and water migration shows that: with continuous rainfall, the pore pressure(or volume water content) of the surface soil(above depth of 15 cm) and the bottom soil(below depth of 85 cm) in the capillary-barrier cover are all high. The high pore pressure(or volumetric water content) of the underlying soil is due to the capillary-barrier effects at the gravel-loess interface, which is the distinct feature of rainfall infiltration water movement different from that of single soil layer. The evaluation of water storage capacity shows that: the effective water storage capacity of the loess-grass cover is 251.95 mm, measured by the rainfall experiments. The theoretical value of the effective water storage Sfac is 218.75 mm, evaluated by the indoor hygroscopic soil-water characteristic curve. The measured value is 15.18% larger than the the theoretical one, and the results are safe. The theoretical value of the effective water storage Sfac is 278.32 mm, evaluated by the field hygroscopic soil-water characteristic curve. The measured value is 9.47%, smaller than the theoretical one, and the results are dangerous. It is suggested that the indoor hygroscopic soil-water characteristiccurve should be adopted in anti-seepage design.
The climate in northwest China is arid and the loess which is technically feasible and economical used for soil cover in landfills is widely distributed. At Jiangchungou Landfill, Xi'an, the first large size loess-grass capillary barrier cover 20 m×30 m is built, and the extreme rainfall experiments are carried out. The results of water distribution tests show that: with 214.8 mm rainfall, the slope runoff is 1.7 mm, accounting for 0.8% of the total rainfall, and the storage of soil(containing evaporation) is 199.57 mm, accounting for 92.9% of the total rainfall, and the leakage is 11.53 mm, accounting for 6.3% of the rainfall. The analysis of matrix suction and water migration shows that: with continuous rainfall, the pore pressure(or volume water content) of the surface soil(above depth of 15 cm) and the bottom soil(below depth of 85 cm) in the capillary-barrier cover are all high. The high pore pressure(or volumetric water content) of the underlying soil is due to the capillary-barrier effects at the gravel-loess interface, which is the distinct feature of rainfall infiltration water movement different from that of single soil layer. The evaluation of water storage capacity shows that: the effective water storage capacity of the loess-grass cover is 251.95 mm, measured by the rainfall experiments. The theoretical value of the effective water storage Sfac is 218.75 mm, evaluated by the indoor hygroscopic soil-water characteristic curve. The measured value is 15.18% larger than the the theoretical one, and the results are safe. The theoretical value of the effective water storage Sfac is 278.32 mm, evaluated by the field hygroscopic soil-water characteristic curve. The measured value is 9.47%, smaller than the theoretical one, and the results are dangerous. It is suggested that the indoor hygroscopic soil-water characteristiccurve should be adopted in anti-seepage design.
引文
[1]贾官伟.固废堆场终场土质覆盖层中水份运移规律及调控方法研究[D].杭州:浙江大学,2010.(JIA Guan-wei.Study on the water transport in the landfill earthen final cover and its controlling method[D].Hangzhou:Zhejiang University,2010.(in Chinese))
[2]DWYER S F.Water balance measurements and computer simulations of landfill covers[D].New Mexico:The University of New Mexico,2003.
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[4]STORMONT J C.The effectiveness of two capillary barriers on a 10%slope[J].Geotechnical and Geological Engineering,1996,14(4):243-267.
[5]STORMONT J C,MORRIS C E.Method to estimate water storage capacity of capillary barriers[J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,1998,124(6):297-303.
[6]KHIRE M,BENSON C,BOSSCHER P,et al.Field-scale comparison of capillary and resistive landfill covers in an arid climate[C]//14th Annual American Geophysical Union Hydrology Days.New Orleans,1994:5-8.
[7]AUBERTIN M,CIFUENTES E,APITHY S A,et al.Analyses of water diversion along inclined covers with capillary barrier effects[J].Canadian Geotechnical Journal,2009,46:1146-1164.
[8]YANG Hong,RAHARDJO H,LEONG E C,et al.A study of infiltration on three sand capillary barriers[J].Canadian Geotechnical Journal,2004,41:629-643.
[9]BONAPARTE R,GROSS B A,DANIEL D E,et al.Draft technical guidance for rcra/cercla final covers[S].Response,Office of Solid Waste,2004.
[10]BENSON C H,KHIRE M V.Earthen covers for semi-arid and arid climates[J].Geotechnical Special Publication,1995(53):20-217.
[11]BENSON C H,ALBRIGHT W H,ROESLER A C,et al.Evaluation of final cover performance:field data from the alternative cover assessment program(ACAP)[J].Proc Waste Management,2002,2:1-15.
[12]ROSS B.The diversion capacity of capillary barriers[J].Water Resources Research,1990,26(10):2625-2629.
[13]ALBRIGHT W H,BENSON C H,GEE G W,et al.Field water balance of landfill final covers[J].Journal of Environmental Quality,2004,33(6):2317.
[14]焦卫国,詹良通,孔令刚,等.黄土-碎石覆盖层毛细阻滞效应及设计厚度分析[J].浙江大学学报(工学版),2016,50(11):2128-2134.(JIAO Wei-guo,ZHAN Liang-tong,LAN Ji-wu,et al.Verification of capillary barrier effect of clayey loess-gravel cover and analysis of design thickness[J].Journal of Zhejiang University:Engineering Science,2016,50(11):2128-2134.(in Chinese))
[15]詹良通,焦卫国,孔令刚,等.黄土作为西北地区填埋场土质覆盖层材料可行性及设计厚度分析[J].岩土力学,2014,12(3):384-389.(ZHAN Liang-tong,JIAO Wei-guo,KONGLing-gang,et al.Feasibility analysis of using loess as soil cover material for landfills in the northwest of China[J].Rock and Soil Mechanics,2014,35(12):3361-3369.(in Chinese))
[16]赵慧,刘川顺,王伟,等.垃圾填埋场腾发覆盖系统控制渗滤效果的研究[J].中国给水排水,2008,24(9):86-89.(ZHAO Hui,LIU Chuan-shun,WANG Wei,et al.Study of leachate control effect of evapotranspiration landfill cover system[J].China Water&Wastewater,2008,24(9):86-89.(in Chinese))
[17]陆海军,栾茂田,张金利.垃圾填埋场传统封顶和ET封顶的比较研究[J].岩土力学,2009,30(2):509-514.(LUHai-jun,LUAN Mao-tian,ZHANG Jin-li.Research on comparision between traditional compacted clay and evapotranspiration cover systems of landfill[J].Rock and Soil Mechanics,2009,30(2):509-514.(in Chinese))
[18]NG C W W,WOONA K X,LEUNGA A K,et al.Experimental investigation of induced suction distribution in a grasscovered soil[J].Ecological Engineering,2013,52:219-223.
[19]邓林恒,詹良通,陈云敏,等.含非饱和导排层的毛细阻滞型覆盖层性能模型试验研究[J].岩土工程学报,2012,34(1):75-80.(DENG Lin-heng,ZHAN Liang-tong,CHENYun-min,et al.Model tests on capillary-barrier cover with unsaturated drainage layer[J].Chinese Journal of Geotechnical Engineering,2012,34(1):75-80.(in Chinese))
[20]张文杰,耿潇.垃圾填埋场毛细阻滞型腾发封顶工作机理及性能分析[J].岩土工程学报,2016,38(3):454-459.(ZHANG Wen-jie,GENG Xiao.Performance and mechanism of capillary-barrier evaportranspiration cover of landfills[J].Chinese Journal of Geotechnical Engineering,2016,38(3):454-459.(in Chinese))
[21]张文杰,邱战洪,朱成仁,等.长三角地区填埋场ET封顶系统的性能评价[J].岩土工程学报,2009,31(3):384-389.(ZHANG Wen-jie,QIU Zhan-hong,ZHU Cheng-ren,et al.Evaluation of evapotranspiration covers of landfills in Yangtze river delta region[J].Chinese Journal of Geotechnical Engineering,2009,31(3):384-389.(in Chinese))
[22]张文杰,林午,董林兵.垃圾填埋场毛细阻滞型腾发封顶模型试验[J].岩土力学,2014,35(5):1263-1268.(ZHANG Wen-jie,LIN Wu,DONG Lin-bing.Model test of a capillary barrier evapotranspiration cover for landfills[J].Rock and Soil Mechanics,2014,35(5):1263-1268.(in Chinese))
[23]康绍忠,刘晓明,熊运章.土壤-植物-大气连续体水分传输理论及其应用[M].北京:水利电力出版社,1994:22-26.(KANG Shao-zhong,LIU Xiao-ming,XIONGYun-zhang.Water transport theory and its application in soilplant-atmosphere continuum[M].Beijing:Water Conservancy and Electricity Press,1994:22-26.(in Chinese))
[24]CRAIG H.BENSON.Final Covers for waste containment systems a north american perspective[C]//XVII Conference of Geotecnics of Torino“Control and Management of Subsoil Pollutants”.Torino,1999.
[25]STORMONT J C.The performance of two capillary barriers during constant infiltration,landfill closures,ASCE,GSP No.53[J].Geotechnical and Geological Engineering,1995:77-92.
[26]DENNY Tami,HARIANTO Rahardjo,ENG-CHOON Leong,et al.Design and laboratory verification of a physical model of sloping capillary barrier[J].Geotechnical and Geological Engineering,2004,41:814-830.
[27]VAN Genuchten M T.A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J].Soil Sci Soc Am J,1980,44(5):892-898.
[2]DWYER S F.Water balance measurements and computer simulations of landfill covers[D].New Mexico:The University of New Mexico,2003.
[3]STORMONT J C.Unsaturated drainage layers for diversion of infiltrating water[J].Journal of Irrigation and Drainage Engineering,1997,123:364-366.
[4]STORMONT J C.The effectiveness of two capillary barriers on a 10%slope[J].Geotechnical and Geological Engineering,1996,14(4):243-267.
[5]STORMONT J C,MORRIS C E.Method to estimate water storage capacity of capillary barriers[J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,1998,124(6):297-303.
[6]KHIRE M,BENSON C,BOSSCHER P,et al.Field-scale comparison of capillary and resistive landfill covers in an arid climate[C]//14th Annual American Geophysical Union Hydrology Days.New Orleans,1994:5-8.
[7]AUBERTIN M,CIFUENTES E,APITHY S A,et al.Analyses of water diversion along inclined covers with capillary barrier effects[J].Canadian Geotechnical Journal,2009,46:1146-1164.
[8]YANG Hong,RAHARDJO H,LEONG E C,et al.A study of infiltration on three sand capillary barriers[J].Canadian Geotechnical Journal,2004,41:629-643.
[9]BONAPARTE R,GROSS B A,DANIEL D E,et al.Draft technical guidance for rcra/cercla final covers[S].Response,Office of Solid Waste,2004.
[10]BENSON C H,KHIRE M V.Earthen covers for semi-arid and arid climates[J].Geotechnical Special Publication,1995(53):20-217.
[11]BENSON C H,ALBRIGHT W H,ROESLER A C,et al.Evaluation of final cover performance:field data from the alternative cover assessment program(ACAP)[J].Proc Waste Management,2002,2:1-15.
[12]ROSS B.The diversion capacity of capillary barriers[J].Water Resources Research,1990,26(10):2625-2629.
[13]ALBRIGHT W H,BENSON C H,GEE G W,et al.Field water balance of landfill final covers[J].Journal of Environmental Quality,2004,33(6):2317.
[14]焦卫国,詹良通,孔令刚,等.黄土-碎石覆盖层毛细阻滞效应及设计厚度分析[J].浙江大学学报(工学版),2016,50(11):2128-2134.(JIAO Wei-guo,ZHAN Liang-tong,LAN Ji-wu,et al.Verification of capillary barrier effect of clayey loess-gravel cover and analysis of design thickness[J].Journal of Zhejiang University:Engineering Science,2016,50(11):2128-2134.(in Chinese))
[15]詹良通,焦卫国,孔令刚,等.黄土作为西北地区填埋场土质覆盖层材料可行性及设计厚度分析[J].岩土力学,2014,12(3):384-389.(ZHAN Liang-tong,JIAO Wei-guo,KONGLing-gang,et al.Feasibility analysis of using loess as soil cover material for landfills in the northwest of China[J].Rock and Soil Mechanics,2014,35(12):3361-3369.(in Chinese))
[16]赵慧,刘川顺,王伟,等.垃圾填埋场腾发覆盖系统控制渗滤效果的研究[J].中国给水排水,2008,24(9):86-89.(ZHAO Hui,LIU Chuan-shun,WANG Wei,et al.Study of leachate control effect of evapotranspiration landfill cover system[J].China Water&Wastewater,2008,24(9):86-89.(in Chinese))
[17]陆海军,栾茂田,张金利.垃圾填埋场传统封顶和ET封顶的比较研究[J].岩土力学,2009,30(2):509-514.(LUHai-jun,LUAN Mao-tian,ZHANG Jin-li.Research on comparision between traditional compacted clay and evapotranspiration cover systems of landfill[J].Rock and Soil Mechanics,2009,30(2):509-514.(in Chinese))
[18]NG C W W,WOONA K X,LEUNGA A K,et al.Experimental investigation of induced suction distribution in a grasscovered soil[J].Ecological Engineering,2013,52:219-223.
[19]邓林恒,詹良通,陈云敏,等.含非饱和导排层的毛细阻滞型覆盖层性能模型试验研究[J].岩土工程学报,2012,34(1):75-80.(DENG Lin-heng,ZHAN Liang-tong,CHENYun-min,et al.Model tests on capillary-barrier cover with unsaturated drainage layer[J].Chinese Journal of Geotechnical Engineering,2012,34(1):75-80.(in Chinese))
[20]张文杰,耿潇.垃圾填埋场毛细阻滞型腾发封顶工作机理及性能分析[J].岩土工程学报,2016,38(3):454-459.(ZHANG Wen-jie,GENG Xiao.Performance and mechanism of capillary-barrier evaportranspiration cover of landfills[J].Chinese Journal of Geotechnical Engineering,2016,38(3):454-459.(in Chinese))
[21]张文杰,邱战洪,朱成仁,等.长三角地区填埋场ET封顶系统的性能评价[J].岩土工程学报,2009,31(3):384-389.(ZHANG Wen-jie,QIU Zhan-hong,ZHU Cheng-ren,et al.Evaluation of evapotranspiration covers of landfills in Yangtze river delta region[J].Chinese Journal of Geotechnical Engineering,2009,31(3):384-389.(in Chinese))
[22]张文杰,林午,董林兵.垃圾填埋场毛细阻滞型腾发封顶模型试验[J].岩土力学,2014,35(5):1263-1268.(ZHANG Wen-jie,LIN Wu,DONG Lin-bing.Model test of a capillary barrier evapotranspiration cover for landfills[J].Rock and Soil Mechanics,2014,35(5):1263-1268.(in Chinese))
[23]康绍忠,刘晓明,熊运章.土壤-植物-大气连续体水分传输理论及其应用[M].北京:水利电力出版社,1994:22-26.(KANG Shao-zhong,LIU Xiao-ming,XIONGYun-zhang.Water transport theory and its application in soilplant-atmosphere continuum[M].Beijing:Water Conservancy and Electricity Press,1994:22-26.(in Chinese))
[24]CRAIG H.BENSON.Final Covers for waste containment systems a north american perspective[C]//XVII Conference of Geotecnics of Torino“Control and Management of Subsoil Pollutants”.Torino,1999.
[25]STORMONT J C.The performance of two capillary barriers during constant infiltration,landfill closures,ASCE,GSP No.53[J].Geotechnical and Geological Engineering,1995:77-92.
[26]DENNY Tami,HARIANTO Rahardjo,ENG-CHOON Leong,et al.Design and laboratory verification of a physical model of sloping capillary barrier[J].Geotechnical and Geological Engineering,2004,41:814-830.
[27]VAN Genuchten M T.A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J].Soil Sci Soc Am J,1980,44(5):892-898.