核废物处置库顶盖毛细屏障中水分流动的实验研究
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摘要
当今世界,原煤、石油、天然气等能源日益紧缺,世界各国都面临着能源危机,核能越来越得到世界各国的重视,核能必定会有一个更大规模的发展。但随着核能的广泛利用,必将产生越来越多的核废物,核废物的如何安全处置成为人们日益关注的焦点。
目前核废物处置多采用地质处理方法。核废物经过加工处理后,再放入处置库与外部环境隔离,尽量避免水分进入处置库。顶盖是放射性废物近地表处置库的重要工程屏障。毛细屏障是顶盖中一个非常重要的部分,一般由细颗粒介质的下面铺设粗颗粒介质而成的。当水分入渗到粗-细颗粒介质交界面上方时,由于毛细作用使得水分不能从细颗粒介质层进入粗颗粒介质层,从而在界面上方积累,如果界面有一定坡度,水分会沿着界面横向传导。本文以喷淋强度、界面坡度和粗砂层厚度为影响因素,系统地展开了其对毛细屏障的效应研究。
通过设计箱体实验,研究在非饱和状态下,以不同的喷淋强度表征不同的降雨情况,分析了其对毛细屏障的影响作用。设定5、15、20和25 mm/d的喷淋强度,测量水分经过粗-细砂介质交界面的相对绕流量。结果表明,在粗砂的厚度不变的前提下,喷淋强度越大,相对绕流量越少,毛细屏障的作用越弱。
研究了粗石英砂的厚度对毛细屏障的影响情况。设定1mm,3mm,5mm,7mm,15mm和30mm等粗石英砂层厚度,在给定喷淋强度下,结果表明绕流量随着粗砂层的厚度增加而增加,证实了粗颗粒介质层的厚度越大,越有利于水分绕流现象的发生。同样,增加毛细屏障的倾斜度,可以增强毛细屏障的阻水能力。
在对相对绕流量的定量观测的同时,也测定了箱体中粗细石英砂层各个位置的基质势,从能量角度对毛细屏障的水流规律作了解释,为更进一步探索复合效应对毛细屏障的影响奠定了基础,为核废物处置库的顶盖设计提供参考。
In the modern world, the lack of energy sources such as coal, petroleum, natural gas becomes serious gradually, all the country in the world have to confront the energy crisis, so nuclear energy will get more and more attention from them. Nuclear energy will get sweeping development as a well developing Energy Substitute. But as the widely use of nuclear energy, there will be more and more nuclear waste. So how to dispose nuclear waste safely will be the focus of the people.
Nuclear waste is often disposed by the method of geological disposal at the present time. First, Processing,then put it in waste repository isolating from external environment, avoiding the water infiltration into the nuclear waste repository to the best of its ability. Cover of low-andintermediate level radioactive waste disposal in near-surface facilities is a useful barrier. One important section, consisting of a coarser soil layer usnderlying a finer soil layer, called capillary barrier. Such a configuration is, in reference to the mechanism of capillary tension that limits water’s downward movement from a finer soil into a coarser soil, causing temporary water storage in the upper soil layer, if the fine-coarse interface is sloped, water in the fine layer can also drain laterally. This paper presents the systemic research of capillary barrier effect, taking infiltration rate、inclination of slope and thickness of coarser soil into account.
To study its performance of the capillary barrier consisting of fine-over-coarse quartz sand layers, it is subjected to different infiltration rates simulating different rainfall in an infiltration box apparatus under unsaturated condition. The barrier was subjected to several infiltration rate of 5,10,15,20 mm/day, successively .Through quantificationally measurement of the diversion water, we can conclude that the bigger the infiltration rate is, the more the penetration water is ,the less diversion water is, the weaker the capillary barrier is, under certain condition of invariable thickness.
The impact of coarse layer thickness on the capillary barrier is investigated .The tests are carried on different thickness of coarse quartz sand ,ranging from 1mm to 30mm in a given infiltration rate. The results indicate that the diversion water becomes larger with the increasing of thickness of coarse layer, confirming the positive effect of bigger thickness of coarse layer on reducing penetration water. The increasing the angle of slope also helps to strengthen the capillary barrier effect.
While quantificationally measureing the diversion water, the matric suction of different locations in and around the capillary barrier are also measured, which has layed the foundation for the exploring the multiplex effect on the capillary barrier, provided the reference for the design of cover in nuclear waste disposal.
目前核废物处置多采用地质处理方法。核废物经过加工处理后,再放入处置库与外部环境隔离,尽量避免水分进入处置库。顶盖是放射性废物近地表处置库的重要工程屏障。毛细屏障是顶盖中一个非常重要的部分,一般由细颗粒介质的下面铺设粗颗粒介质而成的。当水分入渗到粗-细颗粒介质交界面上方时,由于毛细作用使得水分不能从细颗粒介质层进入粗颗粒介质层,从而在界面上方积累,如果界面有一定坡度,水分会沿着界面横向传导。本文以喷淋强度、界面坡度和粗砂层厚度为影响因素,系统地展开了其对毛细屏障的效应研究。
通过设计箱体实验,研究在非饱和状态下,以不同的喷淋强度表征不同的降雨情况,分析了其对毛细屏障的影响作用。设定5、15、20和25 mm/d的喷淋强度,测量水分经过粗-细砂介质交界面的相对绕流量。结果表明,在粗砂的厚度不变的前提下,喷淋强度越大,相对绕流量越少,毛细屏障的作用越弱。
研究了粗石英砂的厚度对毛细屏障的影响情况。设定1mm,3mm,5mm,7mm,15mm和30mm等粗石英砂层厚度,在给定喷淋强度下,结果表明绕流量随着粗砂层的厚度增加而增加,证实了粗颗粒介质层的厚度越大,越有利于水分绕流现象的发生。同样,增加毛细屏障的倾斜度,可以增强毛细屏障的阻水能力。
在对相对绕流量的定量观测的同时,也测定了箱体中粗细石英砂层各个位置的基质势,从能量角度对毛细屏障的水流规律作了解释,为更进一步探索复合效应对毛细屏障的影响奠定了基础,为核废物处置库的顶盖设计提供参考。
In the modern world, the lack of energy sources such as coal, petroleum, natural gas becomes serious gradually, all the country in the world have to confront the energy crisis, so nuclear energy will get more and more attention from them. Nuclear energy will get sweeping development as a well developing Energy Substitute. But as the widely use of nuclear energy, there will be more and more nuclear waste. So how to dispose nuclear waste safely will be the focus of the people.
Nuclear waste is often disposed by the method of geological disposal at the present time. First, Processing,then put it in waste repository isolating from external environment, avoiding the water infiltration into the nuclear waste repository to the best of its ability. Cover of low-andintermediate level radioactive waste disposal in near-surface facilities is a useful barrier. One important section, consisting of a coarser soil layer usnderlying a finer soil layer, called capillary barrier. Such a configuration is, in reference to the mechanism of capillary tension that limits water’s downward movement from a finer soil into a coarser soil, causing temporary water storage in the upper soil layer, if the fine-coarse interface is sloped, water in the fine layer can also drain laterally. This paper presents the systemic research of capillary barrier effect, taking infiltration rate、inclination of slope and thickness of coarser soil into account.
To study its performance of the capillary barrier consisting of fine-over-coarse quartz sand layers, it is subjected to different infiltration rates simulating different rainfall in an infiltration box apparatus under unsaturated condition. The barrier was subjected to several infiltration rate of 5,10,15,20 mm/day, successively .Through quantificationally measurement of the diversion water, we can conclude that the bigger the infiltration rate is, the more the penetration water is ,the less diversion water is, the weaker the capillary barrier is, under certain condition of invariable thickness.
The impact of coarse layer thickness on the capillary barrier is investigated .The tests are carried on different thickness of coarse quartz sand ,ranging from 1mm to 30mm in a given infiltration rate. The results indicate that the diversion water becomes larger with the increasing of thickness of coarse layer, confirming the positive effect of bigger thickness of coarse layer on reducing penetration water. The increasing the angle of slope also helps to strengthen the capillary barrier effect.
While quantificationally measureing the diversion water, the matric suction of different locations in and around the capillary barrier are also measured, which has layed the foundation for the exploring the multiplex effect on the capillary barrier, provided the reference for the design of cover in nuclear waste disposal.
引文
[1]T.Miyazaki.Water Low in Unsaturated Soil in Layered Slopes. J.Hydrol, 102: 201-214,1998.
[2]J.W.Nyhan,T.E.Hakonson,and B.B.Drennon.A Water Balance Study of Two Landfill Cover Designs for Semiarid Regions .Environ Qual,1990,19:281-288.
[3]Kampf.M.Holfelder.T,Montenegro. H. Identification and Parameterization of Flow Processes in Artificial Capillary Barriers.Water Resource Research,2003,39(10):1276-1283.
[4] T.E.Hakonson, K.V.Bostick, L.J.Lane, et al. Hydrologic Evaluation of Four Landfill Cover Designs at Hill Air Force Base, Utah, Los Alamos Natinal Laboratory Report ,1994,LAUR-93-4469.
[5]J.C.Stormont. The Effect of Constant Anistotropy on Capillary Barrier Performance. Water Resour. Res., 1995.31(3), 783-785
[6] J.C.Stormont. The Performance of Two Capillary Barriers during Constant Infiltration, Landfill Closures. ASCE Special Geotechnical Publication No.53, Annual ASCE Convention, October 1995, San Diego.CA.pp. 1995.77-91.
[7] M.T. Walter, J.S. Kirn,T.S. Steenhuis,et al. Funneled Flow Meclianisms in A Sloping Layered Soil:laborarory Investigation.Water Resour. Res.,2000,36(4), 841-849.
[8] Arik Heilig, Tammo S. Steenhuis, M.Todd Walter,et al, Funneled Flow Mechanisms in A Layered Soil:Field Investigations. Journal of Hydrology,2003,279,210-223.
[9] Hong Yang, H. Rahardjo, E.C. Leong, et al.A Study of Infiltration on Three Sand Capillary Barriers.Can. Geotech. J,41:629-643.
[10] John C. Stormont, and Clifford E. Anderson, Members, ASAE.Capillary Barrier Effect from Underlying Coarse Soil Layer.Journal of Geotechnical and Geoenvironmental Engineering,1999,125(8):641-648.
[11] Jason K. Smesrud and John S. Selker.Effect of Soil-Particle Size Contrast on Capillary Barrier Performance . Journal of Geotechnical and Geoenvironmental Engineering,2001,127(10):885-888.
[12]D. E. Hill, J-Y Parlange. Wetting Front Instability In Layered Soils. Soil Sci. Soc. Am. 1972, 36 (5):697-702.
[13] D. Hillel, Raipn S Baker. A Descriptive Theory of Fingering During Infiltration Into Layered Soils. Soil Sci. 1988, 146(1): 51-55.
[14]Ralph.S. Baker and D. Hillel. Laboratory Tests of Theory of Fingering During Infiltration Into Layered Soils. Soil Sci.Soc. Am. J. 1990, Vol. 54:20-30.
[15] R.K.Schultz, R.W.Ridky, and E.O.Donnell, Control of Water Infiltration into Near Surface LLW Disposal Units. U.S.Nuciear Regulatory Commission,USA, 1995 ,NUREG/CR-4918(8),.
[16] Bussiere B, Aubertin M, Chapuis R.P.The Behavior of Inclined Covers Used As Oxygen Barriers. Canadian Geotechnical Journal, 2003,40 (3): 512-535.
[17] Edward O'Donnell, Jacob Philip and Peter Godwin.Performance of Alternative Engineered Covers-results of 12 Years of Cover Performance in Lysimeters at A Humid Region Site, Beltsville,Maryland, WM'99 Conference, 1999,FebAruary 28-March 4
[18] Hndrek Porro.Hydrologic Behavior of Two Engineered Barriers following Extreme Wetting.Journal of Environmental Quality, 2001,30:655-667.
[19]赵沛伦.母质的两层性对土壤持水性能的影响.中国科学院西北水土保持研究所集刊,1985,10:38-46.
[20]王全九,汪志荣,等.层状土入渗机制与数学模型[J].水利学报;1998,01(增刊):76-79.
[21]李书绅,小川宏道,等.超铀核素近地表迁移行为及其处置安全评价方法学研究.中国辐射防护研究院,日本原子力研究所。2001,CIRP/073/ZL/2001-0001/X82.
[22]钱天伟,郭志明,郭谦.包气带黄土介质中核素迁移的双峰机理研究.核技术,2002,23(4).261-266.
[23] Tianwei Qian ,Qian Guo, Fanrong Chen et al. Migration of Sr, Nd and Ce in Unsaturated Chinese Loess Under Artificial Sprinkling Conditions: a Field Migration .Water,Air and Soil Pollution, 2004,159(1):139-150.
[24]王志明,江洪,姚来根,等.非饱和水在双层孔隙介质中渗流的定性实验[J].辐射防护,2003,23(1):8-13.
[25]王志明,姚来根,江洪等.非饱和水通过双层孔隙介质渗流的定量实验[J].辐射防护,2003,23(1):14-18.
[26]J.C.Stormont.The Effectiveness of Two Capillary Barriers on A 10% Slope[J].Geotechnical and Geological Engineering,1996,14:243-267.
[27] J.贝尔,多孔介质流体动力学,张朝深,等译.中国建筑工业出版社,1996.
[28]毛袒熙,段祥宝,李祖贻等.渗流数值计算与程序应用,河海大学出版社,1999.
[29]朱学愚,谢春红.地下水运移模型,中国建筑工业出版社,1990.
[30]雷志栋,杨诗秀,谢森传.土壤水动力学,清华大学出版社,1988,12-18.
[31] Fredlund, D.G., Rahardjo, H., 1993. Soil Mechanics for Unsaturated Soils. Wiley, New York, NY.
[32]王金生,杨志峰,陈家军,王志明.包气带土壤水分滞留特征研究.水利学报,2002,02,1-6.
[33]邵明安,王全九.推求土壤水分运动参数的简单入渗/理论分析.土壤学报,2000,37.
[34]徐绍辉,张佳宝.求土壤水力特征的一种迭代法.土壤学报,2000 ,37(2),271-274.
[35]Van Genuchten M Th. A Closed-from Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils. Soil Sci. Soc. Am J, 1980,44: 892-898.
[36] Brooks RH .Corey AT. Hydraulic Propertics of Porous Media.Hudrol.PaP.,3PP,l-27,Colo.State Univ.,Fort Collins,1964.
[37] Broadbridge P. White I Constant Rate Rainfall Infiltration: A Versatile Nonlinear Model 1. analytic solution[J].Water Resource Res,1988,24(1):145-154.
[38] Visser, W.C. . Progress in the Knowledge About Die Effect of Soil Moisture Content on Plant Production.Tech.Bull.45.lnstitute for Land and Water engagement Research.Wageningen,TheNetherlands,1966.
[39] Assouline S,Tessier D.A Conceptual Model of the Soil Water Retention Curve. Water Resour.Res.,1998,34(2):223-231.
[40]Rawls W J,Brakenseik D J,Saxton K E.Estimation of Soil Water Properties.Tran s. ASAE,1982,25:1316-1320.
[41] Panjit Kumar Ghost.Estimation of Soil Moisture Characteristics from Mechanical Properties of Soils.Soil Sci.,1979,130(2):60-63.
[42]王康,张仁铎,王富庆.基于不完全分形理论的土壤水分特征曲线模型.水利学报,2004,05:1-7.
[2]J.W.Nyhan,T.E.Hakonson,and B.B.Drennon.A Water Balance Study of Two Landfill Cover Designs for Semiarid Regions .Environ Qual,1990,19:281-288.
[3]Kampf.M.Holfelder.T,Montenegro. H. Identification and Parameterization of Flow Processes in Artificial Capillary Barriers.Water Resource Research,2003,39(10):1276-1283.
[4] T.E.Hakonson, K.V.Bostick, L.J.Lane, et al. Hydrologic Evaluation of Four Landfill Cover Designs at Hill Air Force Base, Utah, Los Alamos Natinal Laboratory Report ,1994,LAUR-93-4469.
[5]J.C.Stormont. The Effect of Constant Anistotropy on Capillary Barrier Performance. Water Resour. Res., 1995.31(3), 783-785
[6] J.C.Stormont. The Performance of Two Capillary Barriers during Constant Infiltration, Landfill Closures. ASCE Special Geotechnical Publication No.53, Annual ASCE Convention, October 1995, San Diego.CA.pp. 1995.77-91.
[7] M.T. Walter, J.S. Kirn,T.S. Steenhuis,et al. Funneled Flow Meclianisms in A Sloping Layered Soil:laborarory Investigation.Water Resour. Res.,2000,36(4), 841-849.
[8] Arik Heilig, Tammo S. Steenhuis, M.Todd Walter,et al, Funneled Flow Mechanisms in A Layered Soil:Field Investigations. Journal of Hydrology,2003,279,210-223.
[9] Hong Yang, H. Rahardjo, E.C. Leong, et al.A Study of Infiltration on Three Sand Capillary Barriers.Can. Geotech. J,41:629-643.
[10] John C. Stormont, and Clifford E. Anderson, Members, ASAE.Capillary Barrier Effect from Underlying Coarse Soil Layer.Journal of Geotechnical and Geoenvironmental Engineering,1999,125(8):641-648.
[11] Jason K. Smesrud and John S. Selker.Effect of Soil-Particle Size Contrast on Capillary Barrier Performance . Journal of Geotechnical and Geoenvironmental Engineering,2001,127(10):885-888.
[12]D. E. Hill, J-Y Parlange. Wetting Front Instability In Layered Soils. Soil Sci. Soc. Am. 1972, 36 (5):697-702.
[13] D. Hillel, Raipn S Baker. A Descriptive Theory of Fingering During Infiltration Into Layered Soils. Soil Sci. 1988, 146(1): 51-55.
[14]Ralph.S. Baker and D. Hillel. Laboratory Tests of Theory of Fingering During Infiltration Into Layered Soils. Soil Sci.Soc. Am. J. 1990, Vol. 54:20-30.
[15] R.K.Schultz, R.W.Ridky, and E.O.Donnell, Control of Water Infiltration into Near Surface LLW Disposal Units. U.S.Nuciear Regulatory Commission,USA, 1995 ,NUREG/CR-4918(8),.
[16] Bussiere B, Aubertin M, Chapuis R.P.The Behavior of Inclined Covers Used As Oxygen Barriers. Canadian Geotechnical Journal, 2003,40 (3): 512-535.
[17] Edward O'Donnell, Jacob Philip and Peter Godwin.Performance of Alternative Engineered Covers-results of 12 Years of Cover Performance in Lysimeters at A Humid Region Site, Beltsville,Maryland, WM'99 Conference, 1999,FebAruary 28-March 4
[18] Hndrek Porro.Hydrologic Behavior of Two Engineered Barriers following Extreme Wetting.Journal of Environmental Quality, 2001,30:655-667.
[19]赵沛伦.母质的两层性对土壤持水性能的影响.中国科学院西北水土保持研究所集刊,1985,10:38-46.
[20]王全九,汪志荣,等.层状土入渗机制与数学模型[J].水利学报;1998,01(增刊):76-79.
[21]李书绅,小川宏道,等.超铀核素近地表迁移行为及其处置安全评价方法学研究.中国辐射防护研究院,日本原子力研究所。2001,CIRP/073/ZL/2001-0001/X82.
[22]钱天伟,郭志明,郭谦.包气带黄土介质中核素迁移的双峰机理研究.核技术,2002,23(4).261-266.
[23] Tianwei Qian ,Qian Guo, Fanrong Chen et al. Migration of Sr, Nd and Ce in Unsaturated Chinese Loess Under Artificial Sprinkling Conditions: a Field Migration .Water,Air and Soil Pollution, 2004,159(1):139-150.
[24]王志明,江洪,姚来根,等.非饱和水在双层孔隙介质中渗流的定性实验[J].辐射防护,2003,23(1):8-13.
[25]王志明,姚来根,江洪等.非饱和水通过双层孔隙介质渗流的定量实验[J].辐射防护,2003,23(1):14-18.
[26]J.C.Stormont.The Effectiveness of Two Capillary Barriers on A 10% Slope[J].Geotechnical and Geological Engineering,1996,14:243-267.
[27] J.贝尔,多孔介质流体动力学,张朝深,等译.中国建筑工业出版社,1996.
[28]毛袒熙,段祥宝,李祖贻等.渗流数值计算与程序应用,河海大学出版社,1999.
[29]朱学愚,谢春红.地下水运移模型,中国建筑工业出版社,1990.
[30]雷志栋,杨诗秀,谢森传.土壤水动力学,清华大学出版社,1988,12-18.
[31] Fredlund, D.G., Rahardjo, H., 1993. Soil Mechanics for Unsaturated Soils. Wiley, New York, NY.
[32]王金生,杨志峰,陈家军,王志明.包气带土壤水分滞留特征研究.水利学报,2002,02,1-6.
[33]邵明安,王全九.推求土壤水分运动参数的简单入渗/理论分析.土壤学报,2000,37.
[34]徐绍辉,张佳宝.求土壤水力特征的一种迭代法.土壤学报,2000 ,37(2),271-274.
[35]Van Genuchten M Th. A Closed-from Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils. Soil Sci. Soc. Am J, 1980,44: 892-898.
[36] Brooks RH .Corey AT. Hydraulic Propertics of Porous Media.Hudrol.PaP.,3PP,l-27,Colo.State Univ.,Fort Collins,1964.
[37] Broadbridge P. White I Constant Rate Rainfall Infiltration: A Versatile Nonlinear Model 1. analytic solution[J].Water Resource Res,1988,24(1):145-154.
[38] Visser, W.C. . Progress in the Knowledge About Die Effect of Soil Moisture Content on Plant Production.Tech.Bull.45.lnstitute for Land and Water engagement Research.Wageningen,TheNetherlands,1966.
[39] Assouline S,Tessier D.A Conceptual Model of the Soil Water Retention Curve. Water Resour.Res.,1998,34(2):223-231.
[40]Rawls W J,Brakenseik D J,Saxton K E.Estimation of Soil Water Properties.Tran s. ASAE,1982,25:1316-1320.
[41] Panjit Kumar Ghost.Estimation of Soil Moisture Characteristics from Mechanical Properties of Soils.Soil Sci.,1979,130(2):60-63.
[42]王康,张仁铎,王富庆.基于不完全分形理论的土壤水分特征曲线模型.水利学报,2004,05:1-7.
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