层状土毛细水上升过程中Lucas-Washburn模型评价及修正
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摘要
受界面效应影响,毛细水在层状土中运移规律还难以用描述均质土中水分运移规律的Lucas-Washburn(LW)渗吸模型进行描述。基于此,本文设计了层状土室内模型试验,采用分布式的主动加热光纤法(简称AHFO)监测毛细水上升过程。根据AHFO测试结果,进一步对LW模型进行了修正,提出了适用于描述层状土中毛细水上升规律的ILW模型,并对ILW模型进行了试验验证。试验结果表明:(1)当毛细水湿润锋抵达"黏土(下部)-砂土(上部)"界面时,会产生"毛细屏障作用",从而导致上部砂土中毛细水含水率急剧下降;(2)"毛细屏障作用"由砂土和黏土中的基质吸力不均衡造成,基质吸力大小由含水率决定;(3)当毛细水湿润锋抵达"砂土(下部)-黏土(上部)"界面时,在界面处出现"反毛细屏障作用",从而导致上部黏土层中的含水率比相邻下部砂土层含水率更高;(4)虽然常见的LW模型可准确预测均质土中毛细水上升高度及速率,但受"毛细屏障作用"和"反毛细屏障作用"影响,LW模型在层状土中失效;(5)相比LW模型,ILW模型精度更高,能够更加准确地描述层状土中毛细水上升规律。
In the layered soils,the common Lucas-Washburn( LW) model that describes water movement in homogeneous soil always loses effectiveness under the influence of interfaces between adjacent layers. To characterize vertical water rise under capillary force,a laboratory model test was performed,in which soil moisture content profiles were monitored using the actively heated fiber optic method( AHFO). Based on the results obtained using the AHFO method,the LW model was revised,and an improved LW model( ILW)model was proposed. The experimental results show that( 1) when the capillary water wetting front arrives at a"lower clay-upper sand interface",a "capillary barrier "can obviously be observed,which makes the soil moisture content above the interface much less than that in the lower soil;( 2) the"capillary barrier effect"is caused by the unbalanced matrix suction between sand and clay;( 3) while the capillary water wetting front reaches a "lower sand-upper clay"interface,the "anti-capillary barrier effect"around the middle interface appears,which leads to the soil moisture of the upper clay much larger than that of the lower sand;( 4) theLW model becomes inaccurate due to the impacts of the "capillary barrier action"and "anti-capillary barrier action",and( 5) compared with the LW model,the ILW model has higher accuracy in the layered soils.
In the layered soils,the common Lucas-Washburn( LW) model that describes water movement in homogeneous soil always loses effectiveness under the influence of interfaces between adjacent layers. To characterize vertical water rise under capillary force,a laboratory model test was performed,in which soil moisture content profiles were monitored using the actively heated fiber optic method( AHFO). Based on the results obtained using the AHFO method,the LW model was revised,and an improved LW model( ILW)model was proposed. The experimental results show that( 1) when the capillary water wetting front arrives at a"lower clay-upper sand interface",a "capillary barrier "can obviously be observed,which makes the soil moisture content above the interface much less than that in the lower soil;( 2) the"capillary barrier effect"is caused by the unbalanced matrix suction between sand and clay;( 3) while the capillary water wetting front reaches a "lower sand-upper clay"interface,the "anti-capillary barrier effect"around the middle interface appears,which leads to the soil moisture of the upper clay much larger than that of the lower sand;( 4) theLW model becomes inaccurate due to the impacts of the "capillary barrier action"and "anti-capillary barrier action",and( 5) compared with the LW model,the ILW model has higher accuracy in the layered soils.
引文
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[10] Bosanquet C H. On the flow of liquids into capillary tubes[J]. Philos. Mag,1923,45(267):525-531.
[11] Szekely J,Neumann A W,Chuang Y K. The rate of capillary penetration and the applicability of the Washburn equation[J]. Colloid Interface Sci.,1971,35(2):273-278.
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[16]王贵彦,史秀捧,张建恒,等. TDR法、中子法、重量法测定土壤含水量的比较研究[J].河北农业大学学报,2000,23(3):23-26.[WANG G Y,SHI X P, ZHANG J H, et al. Comparative study on measuring soil moisture by TDR, Neutron and Gravimetric methods[J]. Journal of Agricultural University of Hebei,2000,23(3):23-26.(in Chinese)]
[17]曹鼎峰,施斌,顾凯,等.土的含水率AHFO法测量中分段函数模型建立[J].水文地质工程地质,2016,43(6):41-47.[CAO D F,SHI B,GU K,et al. Establishment of the piecewise function model in the process of soil moisture monitoring with the AHFO method[J]. Hydrogeology&Engineering Geology,2016,43(6):41-47.(in Chinese)]
[18]严珺凡,施斌,曹鼎峰,等.基于碳纤维加热光缆的砂性土渗流场C-DTS分布式监测试验研究[J].岩土力学,2015,36(2):430-436.[YAN J F,SHI B,CAO D F,et al. Experiment study of seepage field monitoring in sandy soil using carbon coated heating optical fiber-based C-DTS[J]. Rock and Soil Mechanics,2015,36(2):430-436.(in Chinese)]
[19]高士桥.毛细力学[M].北京:科学出版社,2010.[GAO S Q. Capillary Mechanics[M]. Beijing:Science Press,2010.(in Chinese)]
[20]德鲁·迈尔斯.表面、界面和胶体:原理及应用[M].北京:化学工业出版社,2005.[Drew Myers.Surface, Interface and Colloid:Principles and Applications[M]. Beijing:Chemical Industry Press,2005.(in Chinese)]
[21]肖建英,李永涛,王丽.利用Van Genuchten模型拟合土壤水分特征曲线[J].地下水,2007,29(5):46-47.[XIAO J Y,LI Y T,WANG L.Fitting soil water characteristic curve based on the Van Genuchten model[J]. Ground Water,2007,29(5):46-47.(in Chinese)]
[22]陈卫金,程东会,陶伟. Van Genuchten模型参数的物理意义[J].水文地质工程地质,2017,44(6):147-153.[CHEN W J,CHENG D H,TAO W. Physical significance of the parameters in the Van Genuchten model[J]. Hydrogeology&Engineering Geology,2017,44(6):147-153.(in Chinese)]
[23]王小华,贾克力,刘景辉,等. Van Genuchten模型在土壤水分特征曲线拟合分析中的应用[J].干旱地区农业研究,2009,27(2):179-183.[WANG X H,JIA K L, LIU J H, et al. Application of Van Genuchten model to analysis of soil moisture characteristic curve[J]. Agricultural research in Arid Areas,2009,27(2):179-183.(in Chinese)]
[24] Li X,Chang S X,Salifu K F. Soil texture and layering effects on water and salt dynamics in the presence of a water table:a review[J].Environmental Reviews,2014,22(1):1-10.
[25]史文娟,汪志荣,沈冰,等.夹砂层土体构型毛管水上升的实验研究[J].水土保持学报,2004,18(6):167-170.[SHI W J,WANG Z R,SHEN B,et al. Soil capillary water upward movement from sand layered soil column[J]. Journal of Soil And Water Conservation, 2004, 18(6):167-170.(in Chinese)]
[26]史文娟,沈冰,汪志荣,等.层状土壤毛管水最大上升高度分析[J].干旱地区农业研究,2007,25(1):94-97.[SHI W J,SHEN B,WANG Z R,et al. Analysis of maximum rising height of capillary water in layered soil[J]. Agricultural research in Arid Areas,2007,25(1):94-97.(in Chinese)]
[27]常琛朝,程东会,钱康.渭河咸阳段非饱和层状沉积物中水分分布特征[J].中国水土保持科学,2017,15(4):104-110.[CHANG S C,CHENG D H,QIAN K. Water content distribution of unsaturated layered sediments of Weihe River in Xianyang section[J]. Science of Soil and Water Conservation,2017,15(4):104-110.(in Chinese)]
[28] Florides G,Kalogirou S. First in situ determination of the thermal performance of a U-pipe borehole heat exchanger, in Cyprus[J]. Applied Thermal Engineering,2008,28(2-3):157-163.
[29] Sayde C, Gregory C, Gil-Rodriguez M, et al.Feasibility of soil moisture monitoring with heated fiber optics[J]. Water Resources Research,2010,46(6):2840-2849.
[30]曹鼎峰,施斌,严珺凡,等.基于C-DTS的土壤含水率分布式测定方法研究[J].岩土工程学报,2014,36(5):910-915.[CAO D F,SHI B,YAN J F,et al. Distributed method for measuring moisture content of soils based on C-DTS[J]. Chinese Journal of Geotechnical Engineering,2014,36(5):910-915.(in Chinese)]
[31]田町正誉.土壤と水との関系特に毛管现象及び渗透に就いて[J].农业土木研究,1931,3(1):1-29.[Tamachi Tadashi. Relationship between soil and water especially on capillary phenomena and penetration[J] Agricultural Civil Engineering Research,1931,3(1):1-29.
[32]李韵珠,胡克林.蒸发条件下黏土层对土壤水和溶质运移影响的模拟[J].土壤学报,2004,41(4):493-502.[LI Y Z,HU K L. Simulation of effects of clay layer on soil water and solute transport under evaporation conditions[J],Acta Pedologica Sinica,2004,41(4):493-502.(in Chinese)]
[33]张志权.不同粉黏粒含量盐渍土的工程性质研究[D].西安:长安大学,2004.[ZHANG Z Q. Study on engineering properties of saline soils with different clay concentrations[D]. Xi’ an:Chang’ an University,2004.(in Chinese)]
[34]崔荣方,陈建生,许霆.无黏性土粒径特征对其渗透性的影响[J].山西建筑,2006,32(6):97-98.[CUI R F,CHEN J S. XU T. Influence of particle size characteristics of non-cohesive soil on its permeability[J]. Shanxi Architecture,2006,32(6):97-98.(in Chinese)]
[2] Mingbin Huang,S Lee Barbour,Amin Elshorbagy,et al. Infiltration and drainage processes in multi-layered coarse soils[J]. Revue Canadienne De La Science Du Sol,2011,91(2):185-197.
[3] Zornberg J G, Bouazza A, Mccartney J S.Geosynthetic capillary barriers:current state ofknowledge[J]. Geosynthetics International,2015,17(5):273-300.
[4] Bruch P G. Laboratory study of evaporative fluxes in homogeneous and layered soils[D]. Saskatoon:University of Saakatoon,1993.
[5] Hill D E. Wetting front instability in layered soils[J]. Soil Science Society of America Journal,1972,36(5):697-702.
[6] Baker R S,Hillel D. Laboratory tests of a theory of fingering during infiltration into layered soils[J]. Soil Science Society of America Journal,1990,54(1):20-30.
[7]付志文,武海英.土中毛细水运移阶段理论研究[J].工程与建设,2013(6):749-751.[FU Z W,WU H Y. Theoretical study on the phase of capillary water migration in soil[J]. Engineering and Construction,2013(6):749-751.(in Chinese)]
[8] Julie D Zettl,S Lee Barbour,Mingbin Huang,et al.Influence of textural layering on field capacity of coarse soils[J]. Canadian Journal of Soil Science,2011,91(2):133.
[9] Washburn E W. Dynamics of capillary flow[J].Phys. Rev.,1921,17(3):273-283.
[10] Bosanquet C H. On the flow of liquids into capillary tubes[J]. Philos. Mag,1923,45(267):525-531.
[11] Szekely J,Neumann A W,Chuang Y K. The rate of capillary penetration and the applicability of the Washburn equation[J]. Colloid Interface Sci.,1971,35(2):273-278.
[12] Quere D. Inertial capillarity[J]. Europhys Lett.,1997,39(5):533-538.
[13] Lucas R. Rate of capillary ascension of liquids[J].Kolloid-Zeitschrift,1918,23:15-22.
[14] Cai J C,Yu B M,Mei M F,et al. Capillary Rise in a Single Tortuous Capillary[J]. Chinese Physics Letters,2010,27(5):148-151.
[15]邓英春,许永辉.土壤水分测量方法研究综述[J].水文,2007,27(4):20-24.[DENG Y C,XU Y H. A Survey of soil moisture measurement methods[J]. Journal of China Hydrology,2007,27(4):20-24.(in Chinese)]
[16]王贵彦,史秀捧,张建恒,等. TDR法、中子法、重量法测定土壤含水量的比较研究[J].河北农业大学学报,2000,23(3):23-26.[WANG G Y,SHI X P, ZHANG J H, et al. Comparative study on measuring soil moisture by TDR, Neutron and Gravimetric methods[J]. Journal of Agricultural University of Hebei,2000,23(3):23-26.(in Chinese)]
[17]曹鼎峰,施斌,顾凯,等.土的含水率AHFO法测量中分段函数模型建立[J].水文地质工程地质,2016,43(6):41-47.[CAO D F,SHI B,GU K,et al. Establishment of the piecewise function model in the process of soil moisture monitoring with the AHFO method[J]. Hydrogeology&Engineering Geology,2016,43(6):41-47.(in Chinese)]
[18]严珺凡,施斌,曹鼎峰,等.基于碳纤维加热光缆的砂性土渗流场C-DTS分布式监测试验研究[J].岩土力学,2015,36(2):430-436.[YAN J F,SHI B,CAO D F,et al. Experiment study of seepage field monitoring in sandy soil using carbon coated heating optical fiber-based C-DTS[J]. Rock and Soil Mechanics,2015,36(2):430-436.(in Chinese)]
[19]高士桥.毛细力学[M].北京:科学出版社,2010.[GAO S Q. Capillary Mechanics[M]. Beijing:Science Press,2010.(in Chinese)]
[20]德鲁·迈尔斯.表面、界面和胶体:原理及应用[M].北京:化学工业出版社,2005.[Drew Myers.Surface, Interface and Colloid:Principles and Applications[M]. Beijing:Chemical Industry Press,2005.(in Chinese)]
[21]肖建英,李永涛,王丽.利用Van Genuchten模型拟合土壤水分特征曲线[J].地下水,2007,29(5):46-47.[XIAO J Y,LI Y T,WANG L.Fitting soil water characteristic curve based on the Van Genuchten model[J]. Ground Water,2007,29(5):46-47.(in Chinese)]
[22]陈卫金,程东会,陶伟. Van Genuchten模型参数的物理意义[J].水文地质工程地质,2017,44(6):147-153.[CHEN W J,CHENG D H,TAO W. Physical significance of the parameters in the Van Genuchten model[J]. Hydrogeology&Engineering Geology,2017,44(6):147-153.(in Chinese)]
[23]王小华,贾克力,刘景辉,等. Van Genuchten模型在土壤水分特征曲线拟合分析中的应用[J].干旱地区农业研究,2009,27(2):179-183.[WANG X H,JIA K L, LIU J H, et al. Application of Van Genuchten model to analysis of soil moisture characteristic curve[J]. Agricultural research in Arid Areas,2009,27(2):179-183.(in Chinese)]
[24] Li X,Chang S X,Salifu K F. Soil texture and layering effects on water and salt dynamics in the presence of a water table:a review[J].Environmental Reviews,2014,22(1):1-10.
[25]史文娟,汪志荣,沈冰,等.夹砂层土体构型毛管水上升的实验研究[J].水土保持学报,2004,18(6):167-170.[SHI W J,WANG Z R,SHEN B,et al. Soil capillary water upward movement from sand layered soil column[J]. Journal of Soil And Water Conservation, 2004, 18(6):167-170.(in Chinese)]
[26]史文娟,沈冰,汪志荣,等.层状土壤毛管水最大上升高度分析[J].干旱地区农业研究,2007,25(1):94-97.[SHI W J,SHEN B,WANG Z R,et al. Analysis of maximum rising height of capillary water in layered soil[J]. Agricultural research in Arid Areas,2007,25(1):94-97.(in Chinese)]
[27]常琛朝,程东会,钱康.渭河咸阳段非饱和层状沉积物中水分分布特征[J].中国水土保持科学,2017,15(4):104-110.[CHANG S C,CHENG D H,QIAN K. Water content distribution of unsaturated layered sediments of Weihe River in Xianyang section[J]. Science of Soil and Water Conservation,2017,15(4):104-110.(in Chinese)]
[28] Florides G,Kalogirou S. First in situ determination of the thermal performance of a U-pipe borehole heat exchanger, in Cyprus[J]. Applied Thermal Engineering,2008,28(2-3):157-163.
[29] Sayde C, Gregory C, Gil-Rodriguez M, et al.Feasibility of soil moisture monitoring with heated fiber optics[J]. Water Resources Research,2010,46(6):2840-2849.
[30]曹鼎峰,施斌,严珺凡,等.基于C-DTS的土壤含水率分布式测定方法研究[J].岩土工程学报,2014,36(5):910-915.[CAO D F,SHI B,YAN J F,et al. Distributed method for measuring moisture content of soils based on C-DTS[J]. Chinese Journal of Geotechnical Engineering,2014,36(5):910-915.(in Chinese)]
[31]田町正誉.土壤と水との関系特に毛管现象及び渗透に就いて[J].农业土木研究,1931,3(1):1-29.[Tamachi Tadashi. Relationship between soil and water especially on capillary phenomena and penetration[J] Agricultural Civil Engineering Research,1931,3(1):1-29.
[32]李韵珠,胡克林.蒸发条件下黏土层对土壤水和溶质运移影响的模拟[J].土壤学报,2004,41(4):493-502.[LI Y Z,HU K L. Simulation of effects of clay layer on soil water and solute transport under evaporation conditions[J],Acta Pedologica Sinica,2004,41(4):493-502.(in Chinese)]
[33]张志权.不同粉黏粒含量盐渍土的工程性质研究[D].西安:长安大学,2004.[ZHANG Z Q. Study on engineering properties of saline soils with different clay concentrations[D]. Xi’ an:Chang’ an University,2004.(in Chinese)]
[34]崔荣方,陈建生,许霆.无黏性土粒径特征对其渗透性的影响[J].山西建筑,2006,32(6):97-98.[CUI R F,CHEN J S. XU T. Influence of particle size characteristics of non-cohesive soil on its permeability[J]. Shanxi Architecture,2006,32(6):97-98.(in Chinese)]