电导率法测沙中水分分布及沙中水分输运实验研究
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摘要
本文参照土壤中的水分输运方程，建立沙中水分输运方程，在恒温恒湿条件下，通过实验及电导率测量的方法研究沙中水分输运的规律。将模拟计算结果与实验数据进行对比，确定沙中水分输运方程的参数，从而进一步完善沙中水分输运方程，为深入研究水在沙中的输运规律及应用提供参考。主要结论如下：
1.根据恒定电路的欧姆定律，在含水均匀的情况下，电导率与含水率呈线性关系，当含水率小于0.12%时，电导率为零，主要原因在于这部分水被沙粒吸收，对电导率没有影响。
2.金属网对实验的影响
本实验通过分层测量玻璃管中的含水率探究水分输运规律，通过建立物理模型模拟计算金属网的存在所引起的误差。设上表面边长L_1=λ_1H,金属网孔的宽度L_2=λ_2L_1，其中，H为长方体模型的高。当λ_1≤0.1，λ_2=0.8时，金属网对电势的影响将大于0.53%范围内，对含水率的影响在0.3%范围内。
3.均匀加入保水剂的沙的持水率最大，且持水率与保水剂的质量成正相关，无保水剂的沙的持水率最小。
4.无保水剂掺入的沙中水分输运规律
由总质量得出的含水率与沙中水分输运方程模拟计算的含水率符合较好，均方差小。由输运方程分层模拟计算得出的含水率与分层测量的等效含水率吻合较好。第一、二层均方差值较小，第三、四层均方差值较大。水分输运模型在总体或分层都可很好的描述沙中水分的输运。
5.均匀掺入保水的沙中水分输运规律
保水剂质量越大，含水率在开始的一段时间内下降越快，随着时间的增大，总含水率下降反而越慢。与无保水剂情况相比较，含水率较大。采用水分输运方程分层模拟计算得出的含水率与分层测量的等效含水率吻合较好，其中，第一、二层均方差值较小，第三、四层均方差值较大。与无保水剂情况相比较，均方差较大。水分输运模型在总体或分层都可很好的描述均匀掺入保水剂的沙中水分的输运。
6.中间层掺入保水剂的沙中水分输运规律
在中层掺入保水剂情况下，中间层的水分蒸发慢，含水率下降慢。与无保水剂的情况相比，中间层的含水率较大，与均匀掺入保水剂的情况相比，含水率较小。实验较好的验证了水分输运方程的有效性。
In this paper, the law of water transporting in soil is cited to study how the water transportin sand under a constant temperature and humidity cases. The moisture content of sand andmixing super absorbent polymers can be measured by electric conductivity through the creationof physical models. We adjust the diffusion coefficient to make the simulation results consistentwith the experiment data. These conclusions can provide reference for further research of watertransport. The conclusions:
1. The conductivity of wet sand is linear to the moisture content when water is evenly distributedin sand. If the moisture content below0.12%, the conductivity value decrease to zero. There isno effect to conductivity because the water is assimilated by sand.
2. There is a cubic which side lengths both meetL_1=λ_1H,L_2=λ_2L_1. Ifλ_1is fixed, the error ofpotential is increase with increase ofλ_2, the error of moisture content is decrease with increaseofλ_2. The reason is that the big make the potential of the metal net surface diminish, but betterfor water transport. Ifλ_2is fixed, the error of potential and moisture content are diminish withdecrease ofλ_1. The reason is that the error of potential is distributed in a small region aroundmetal net, had no effect on the middle sand. If the size of physical model meetλ_1≤0.1andλ_2=0.8, error of potential and moisture content less than0.53%and0.3%.
3. The water rate of the sand that super absorbent polymers evenly distributed is the biggestamong the three situation. The water rate and quality of super absorbent polymers are positivecorrelated.
4. The law of water transport in sand.
Moisture content changing with time is becoming smaller, the decreasing speed of themoisture content of glass B is less than glass A.The mainly reason is that the water affected by gravity downward transport, the bottom water of glass B is more than glass A, so there is lesswater to be evaporated, the moisture content of glass B is bigger than glass A. The curve of errorand diffusion parameter D0which determined by the total quality is smooth than determined byeach layer of moisture content.
5. The law of water transport in sand with super absorbent polymers.
The heavier the quality of super absorbent polymers is, the faster the speed of the decline ofthe moisture content is. The moisture content in this case is bigger than the sand without superabsorbent polymers. The greater the quality of super absorbent polymers, the bigger the diffusionparameter D0but the size and the quality of super absorbent polymers is out of multiples.
6. The law of water transport in sand with super absorbent polymers in the middle layer.The super absorbent polymers in the middle layer affect the bottom water transport law. Themoisture content of simulation and the moisture content error between simulation andexperiment is about5by input parameters, so it is in good conformity.
1.根据恒定电路的欧姆定律，在含水均匀的情况下，电导率与含水率呈线性关系，当含水率小于0.12%时，电导率为零，主要原因在于这部分水被沙粒吸收，对电导率没有影响。
2.金属网对实验的影响
本实验通过分层测量玻璃管中的含水率探究水分输运规律，通过建立物理模型模拟计算金属网的存在所引起的误差。设上表面边长L_1=λ_1H,金属网孔的宽度L_2=λ_2L_1，其中，H为长方体模型的高。当λ_1≤0.1，λ_2=0.8时，金属网对电势的影响将大于0.53%范围内，对含水率的影响在0.3%范围内。
3.均匀加入保水剂的沙的持水率最大，且持水率与保水剂的质量成正相关，无保水剂的沙的持水率最小。
4.无保水剂掺入的沙中水分输运规律
由总质量得出的含水率与沙中水分输运方程模拟计算的含水率符合较好，均方差小。由输运方程分层模拟计算得出的含水率与分层测量的等效含水率吻合较好。第一、二层均方差值较小，第三、四层均方差值较大。水分输运模型在总体或分层都可很好的描述沙中水分的输运。
5.均匀掺入保水的沙中水分输运规律
保水剂质量越大，含水率在开始的一段时间内下降越快，随着时间的增大，总含水率下降反而越慢。与无保水剂情况相比较，含水率较大。采用水分输运方程分层模拟计算得出的含水率与分层测量的等效含水率吻合较好，其中，第一、二层均方差值较小，第三、四层均方差值较大。与无保水剂情况相比较，均方差较大。水分输运模型在总体或分层都可很好的描述均匀掺入保水剂的沙中水分的输运。
6.中间层掺入保水剂的沙中水分输运规律
在中层掺入保水剂情况下，中间层的水分蒸发慢，含水率下降慢。与无保水剂的情况相比，中间层的含水率较大，与均匀掺入保水剂的情况相比，含水率较小。实验较好的验证了水分输运方程的有效性。
In this paper, the law of water transporting in soil is cited to study how the water transportin sand under a constant temperature and humidity cases. The moisture content of sand andmixing super absorbent polymers can be measured by electric conductivity through the creationof physical models. We adjust the diffusion coefficient to make the simulation results consistentwith the experiment data. These conclusions can provide reference for further research of watertransport. The conclusions:
1. The conductivity of wet sand is linear to the moisture content when water is evenly distributedin sand. If the moisture content below0.12%, the conductivity value decrease to zero. There isno effect to conductivity because the water is assimilated by sand.
2. There is a cubic which side lengths both meetL_1=λ_1H,L_2=λ_2L_1. Ifλ_1is fixed, the error ofpotential is increase with increase ofλ_2, the error of moisture content is decrease with increaseofλ_2. The reason is that the big make the potential of the metal net surface diminish, but betterfor water transport. Ifλ_2is fixed, the error of potential and moisture content are diminish withdecrease ofλ_1. The reason is that the error of potential is distributed in a small region aroundmetal net, had no effect on the middle sand. If the size of physical model meetλ_1≤0.1andλ_2=0.8, error of potential and moisture content less than0.53%and0.3%.
3. The water rate of the sand that super absorbent polymers evenly distributed is the biggestamong the three situation. The water rate and quality of super absorbent polymers are positivecorrelated.
4. The law of water transport in sand.
Moisture content changing with time is becoming smaller, the decreasing speed of themoisture content of glass B is less than glass A.The mainly reason is that the water affected by gravity downward transport, the bottom water of glass B is more than glass A, so there is lesswater to be evaporated, the moisture content of glass B is bigger than glass A. The curve of errorand diffusion parameter D0which determined by the total quality is smooth than determined byeach layer of moisture content.
5. The law of water transport in sand with super absorbent polymers.
The heavier the quality of super absorbent polymers is, the faster the speed of the decline ofthe moisture content is. The moisture content in this case is bigger than the sand without superabsorbent polymers. The greater the quality of super absorbent polymers, the bigger the diffusionparameter D0but the size and the quality of super absorbent polymers is out of multiples.
6. The law of water transport in sand with super absorbent polymers in the middle layer.The super absorbent polymers in the middle layer affect the bottom water transport law. Themoisture content of simulation and the moisture content error between simulation andexperiment is about5by input parameters, so it is in good conformity.
引文
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[2]Wang Tao, Zhu Zhenda, Wu Wei. Sandy desertification in the north China [J]. Science inChina,2002,45(sup.):23-24.
[3]National Research Council, Board on Sustainable Development, Policy Division, Committeeon Global Change Research. Gobal Enbironmental Change: Research Pathways for the NextDecade[M].Washington D C:National Academy Press,1999.
[4]胡光印,董治宝等.长江源区沙漠化土地遥感调查及分析.2010,30(3):505-509.
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[6] LUO. Bin, LU Qi, ZHOU Huang-shui. Present situation, cause and control way ofesertification in China. Journal of Desert Research,1999,19(4):318-331.
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[8]杨持.沙漠化控制与治理技术[M].化学工业出版社.2004.
[9]赵婧,程伍群.我国土地沙漠化防治策略研究[J].安徽农业科学.39(13):7868-7869.
[10] MA Xue-hua. Forest damage and flood of upper reaches of Yangtze River. In Reflection onthe Flood Disaster of Yangtze River in1998,and Countermeasures of Controlling Flood andReducing Disasters in21st Century. Beijing, Ocean Press,1998.
[11]何艳梅.跨国水资源保护的法律措施——兼及中国的实践[J].2009.18(1):931-936.
[12]Wang G, Cheng G. Cases and solution: The characteristics of water resources and thechanges of the hydrological process and environment in the arid zone of northwest China[J].Environmental Geology,2000,39(7):783-790.
[13]隋红建,曾德超,陈发祖.不同覆盖条件对土壤水热分布影响的计算机模拟Ⅱ—有限元分析及应用[J].地理学报,1992,47(2):181-187.
[14]冶运涛.流域虚拟仿真中水沙模拟时刻过程三维可视化[J].水科学进展.2011.22(2):249-257.
[15]W. R. Gardner. Solution of the Flow Equation for the Dry of Soils and Other PorousMedia[J]. Soil Science Society Proceedings,1959,183-187.
[16]Tsutomu Yamanaka, Mitsuhiro Inoue. Effects of gravel mulch on water vapor transfer aboveand below the soil surface [J]. Agricultural Water Management,2004,67:145-155.
[17]张智峰.保水剂研究进展[J].磷肥与复肥,201025(5)：63-66.
[18]张建峰,杨俊诚.多功能固沙保水剂性能及其效果的研究[J].农业环境科学报,2008,27(5),1820-1825.
[19]陈学文土壤特性对保水剂吸水性能的影响[J].安徽农业科学,2011,39(12):7030－7031.
[20] Junping Z, Aiqin W. Utilization of Starch and Clay for the Preparation of SuperabsorbentComposite [J]. Bioresource Technology,2006,102:1-6.
[21]熊耀兵,张杰等.沙中水分输运模型实验研究[J].陕西科技大学学报,2011.29(1):87-89.
[22]郭硕鸿.电动力学[M].2008.
[23]熊彬等.MATLAB在有限差分中的应用.桂林工学院学报.2001.21(2):104-107.
[24]王峰峰,王彩华等,二维对流扩散方程的紧致差分格式[J].天津师范大学学报(自然科学版).2011.31(1).11-16.
[25]赵凯华,陈熙谋.新概念物理教程电磁学.高等教育出版社,2006.12.
[26]陆金甫,关治.偏微分方程数值解法.清华大学出版社,2003.
[27]陈玉水.耐盐吸水抗旱剂及其在甘蔗上的应用研究[J].甘蔗,1997,4(4):11-14.
[28]张富仓,李继成,雷艳.保水剂对土壤持肥特性的影响研究[J].应用基础与工程科学报,2010,18(1):120,2010,18(1):120,2010,18(1):120-128.
[29]国家林业局.中国荒漠化和沙化状况公报[R].2009.
[30]张翠莲.我国北方的土地利用与沙漠化[J].内蒙古环境科学,2009,21(6):116-118.
[31]陈小洁.保护21世纪的中国水资源[J].蚌埠党校学报.2005,4:24-25.
[32]井上光弘,野村安治等.掺砂保水剂的吸水能力和保水能力评价[J].水土保持科技情报,1994,(3):22-24.
[33]张富仓,李继成,雷艳.保水剂对土壤持肥特性的影响研究[J].应用基础与工程科学报,2010,18(1):120,2010,18(1):120,2010,18(1):120-128.
[34]朱震达.沙漠化概念的新进展[J].干旱区研究,1993,10(4):8-10.
[35]朱俊凤,朱震达.中国沙漠化防治[M].中国林业出版社,1999.
[36]刘拓,张克斌,林琼.国土地沙漠化防治策略[M].中国林业出版社.2006.11-20.
[37]裘善文.中国东北西部沙地与沙漠化[M].科学出版社.2008.
[38]罗斌,卢琦等.我国荒漠化现状、成因与防治对策[J].中国沙漠.1999,19(4):318-331.
[39]张建峰,杨俊诚.多功能固沙保水剂性能及其效果的研究[J].农业环境科学学报,2008,27(5),1820-1825.
[40]王涛,吴薇等.中国北方土地沙漠化演变气势分析[J].中国沙漠2003,23(3):209-214.
[2]Wang Tao, Zhu Zhenda, Wu Wei. Sandy desertification in the north China [J]. Science inChina,2002,45(sup.):23-24.
[3]National Research Council, Board on Sustainable Development, Policy Division, Committeeon Global Change Research. Gobal Enbironmental Change: Research Pathways for the NextDecade[M].Washington D C:National Academy Press,1999.
[4]胡光印,董治宝等.长江源区沙漠化土地遥感调查及分析.2010,30(3):505-509.
[5] China country paper to combat desertification, China National Committee for theimplementation of the United Nations convention to Comabat esertification (CCICCD)[Z].China Forestry Press.1997.
[6] LUO. Bin, LU Qi, ZHOU Huang-shui. Present situation, cause and control way ofesertification in China. Journal of Desert Research,1999,19(4):318-331.
[7] Lerche Ian. Natural and anthropogenic environmental problems[J].Energy&Environment,2001,12(1):73-88.
[8]杨持.沙漠化控制与治理技术[M].化学工业出版社.2004.
[9]赵婧,程伍群.我国土地沙漠化防治策略研究[J].安徽农业科学.39(13):7868-7869.
[10] MA Xue-hua. Forest damage and flood of upper reaches of Yangtze River. In Reflection onthe Flood Disaster of Yangtze River in1998,and Countermeasures of Controlling Flood andReducing Disasters in21st Century. Beijing, Ocean Press,1998.
[11]何艳梅.跨国水资源保护的法律措施——兼及中国的实践[J].2009.18(1):931-936.
[12]Wang G, Cheng G. Cases and solution: The characteristics of water resources and thechanges of the hydrological process and environment in the arid zone of northwest China[J].Environmental Geology,2000,39(7):783-790.
[13]隋红建,曾德超,陈发祖.不同覆盖条件对土壤水热分布影响的计算机模拟Ⅱ—有限元分析及应用[J].地理学报,1992,47(2):181-187.
[14]冶运涛.流域虚拟仿真中水沙模拟时刻过程三维可视化[J].水科学进展.2011.22(2):249-257.
[15]W. R. Gardner. Solution of the Flow Equation for the Dry of Soils and Other PorousMedia[J]. Soil Science Society Proceedings,1959,183-187.
[16]Tsutomu Yamanaka, Mitsuhiro Inoue. Effects of gravel mulch on water vapor transfer aboveand below the soil surface [J]. Agricultural Water Management,2004,67:145-155.
[17]张智峰.保水剂研究进展[J].磷肥与复肥,201025(5)：63-66.
[18]张建峰,杨俊诚.多功能固沙保水剂性能及其效果的研究[J].农业环境科学报,2008,27(5),1820-1825.
[19]陈学文土壤特性对保水剂吸水性能的影响[J].安徽农业科学,2011,39(12):7030－7031.
[20] Junping Z, Aiqin W. Utilization of Starch and Clay for the Preparation of SuperabsorbentComposite [J]. Bioresource Technology,2006,102:1-6.
[21]熊耀兵,张杰等.沙中水分输运模型实验研究[J].陕西科技大学学报,2011.29(1):87-89.
[22]郭硕鸿.电动力学[M].2008.
[23]熊彬等.MATLAB在有限差分中的应用.桂林工学院学报.2001.21(2):104-107.
[24]王峰峰,王彩华等,二维对流扩散方程的紧致差分格式[J].天津师范大学学报(自然科学版).2011.31(1).11-16.
[25]赵凯华,陈熙谋.新概念物理教程电磁学.高等教育出版社,2006.12.
[26]陆金甫,关治.偏微分方程数值解法.清华大学出版社,2003.
[27]陈玉水.耐盐吸水抗旱剂及其在甘蔗上的应用研究[J].甘蔗,1997,4(4):11-14.
[28]张富仓,李继成,雷艳.保水剂对土壤持肥特性的影响研究[J].应用基础与工程科学报,2010,18(1):120,2010,18(1):120,2010,18(1):120-128.
[29]国家林业局.中国荒漠化和沙化状况公报[R].2009.
[30]张翠莲.我国北方的土地利用与沙漠化[J].内蒙古环境科学,2009,21(6):116-118.
[31]陈小洁.保护21世纪的中国水资源[J].蚌埠党校学报.2005,4:24-25.
[32]井上光弘,野村安治等.掺砂保水剂的吸水能力和保水能力评价[J].水土保持科技情报,1994,(3):22-24.
[33]张富仓,李继成,雷艳.保水剂对土壤持肥特性的影响研究[J].应用基础与工程科学报,2010,18(1):120,2010,18(1):120,2010,18(1):120-128.
[34]朱震达.沙漠化概念的新进展[J].干旱区研究,1993,10(4):8-10.
[35]朱俊凤,朱震达.中国沙漠化防治[M].中国林业出版社,1999.
[36]刘拓,张克斌,林琼.国土地沙漠化防治策略[M].中国林业出版社.2006.11-20.
[37]裘善文.中国东北西部沙地与沙漠化[M].科学出版社.2008.
[38]罗斌,卢琦等.我国荒漠化现状、成因与防治对策[J].中国沙漠.1999,19(4):318-331.
[39]张建峰,杨俊诚.多功能固沙保水剂性能及其效果的研究[J].农业环境科学学报,2008,27(5),1820-1825.
[40]王涛,吴薇等.中国北方土地沙漠化演变气势分析[J].中国沙漠2003,23(3):209-214.
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