ISWC OpenIR  > 水保所2018--届毕业生论文
土壤内力作用对黄土母质发育土壤水力学性质的影响及模拟
Alternative TitleWater Infiltration and Simulation of Typical Loess-developed Soils Affected by Soil Internal Forces
杨志花
Subtype硕士
Thesis Advisor赵世伟
2019-05-22
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name工程硕士
Degree Discipline环境工程
Keyword内力作用 水分入渗 水分特征曲线 入渗模型 水分特征曲线模型
Abstract

水资源短缺是黄土高原地区农业生产和生态环境建设中遇到的主要限制因子。 土壤水分入渗作为地表水转化为土壤水的一个重要过程, 不仅决定着土壤对雨水和灌溉水等有限水源的利用程度,而且也深刻影响着地表径流和土壤侵蚀强度。 土壤水分入渗特性受到土壤内外部许多因素的影响。其中团聚体稳定性是影响土壤水分运动的重要因素。 新近的研究表明, 介观尺度土壤颗粒间的内力作用(包括静电斥力、分子引力和水合斥力) 可高达数百个大气压, 是土壤团聚体破碎的主要推动力。 而团聚体的破碎将会改变土壤孔隙状况,进而对土壤水分运动产生影响。然而目前有关土壤颗粒间内力作用对土壤水力性质的影响研究尚且较少,且考虑颗粒间内力作用后经典水分入渗模型的适用性还有待进一步验证。因此,本研究选取四种典型的黄土母质发育土壤(黑垆土、黄绵土、褐土和塿土)为研究对象,通过理论计算与试验验证相结合的方法,探究土壤内力作用对土壤水分入渗过程的影响,并采用经典土壤水分入渗模型和水分特征曲线模型进行拟合, 验证并比较分析了模型的适用性。 本研究取得以下结果:
(1) 定量获取了几种典型黄土内力作用大小及分布特征。 随着电解质浓度的降低, 四种供试土壤的表面电位(绝对值)、表面电场强度增大,静电斥力、DLVO 力和净作用力皆不同程度地增大。土壤颗粒间的内力作用皆随相邻颗粒间
距离的增加而减小。 净作用力仅在浓度为 1 mol·L-1 时出现净吸引力。 黑垆土、黄绵土、褐土和塿土的临界电位分别是-211.9、 -203.6、 -223.3 和-232.6 mV。对应的临界浓度都约为 0.01 mol·L-1。 当颗粒表面电位大于该临界值,以颗粒间距离 2 nm 为例, 颗粒间净作用力均保持不变;而当电位小于该临界值时,随土粒表面电位的增加颗粒间净作用力增加。这表明,土粒间内力作用随体系电解质浓度减小, 电位的增大将表现出先增大而后减小的趋势。
(2) 系统研究了不同内力作用下土壤水分入渗特性。 随着电解质浓度的降低,土壤颗粒间净斥力作用的增强, 水分入渗速率降低,湿润锋运移速度降低,土壤水分累积入渗量减少。 其中电解质浓度 0.01 mol·L-1 是控制水分运动的临界浓度。 当电解质浓度低于临界浓度时, 水分入渗速率、 湿润锋运移速度等参数不再随电解质浓度而发生变化; 而当电解质浓度高于临界浓度时, 随浓度的增大,水分入渗速率、湿润锋运移速度、水分累积入渗量均增加。Kostiakov 模型和 Philip模型均可对累积入渗量随测定时间的变化情况进行较高程度地拟合, 其中Kostiakov 模型的拟合效果更好。
(3)探讨了不同内力作用下土壤持水性能的变化。随着电解质浓度的降低,净斥力作用增强,土壤饱和导水率减小,土壤持水能力增强。 van Genuchten 模型和 Gardner 模型皆能较好地拟合四种土壤不同内力作用下的水分特征曲线, 总体分析, Gardner 模型对不同内力作用下的水分特征曲线变化拟合效果更好。
 

Other Abstract

The shortage of water resources is the main limiting factor in agricultural
production and ecological environment construction in the Loess Plateau of China. As an important process for the conversion of surface water to soil water, soil water infiltration not only determines utilization rate of the limited water sources, such as rainwater and irrigation water, but also profoundly affects intensity of surface runoff and soil erosion. Soil water infiltration is affected by many internal and external factors. The stability of aggregates is an important factor affecting soil water movement. Recent researches have demonstrated that soil internal forces, including electrostatic, van der Waals and hydration forces, can be as high as hundreds of atmospheres, which is the main driving force for soil aggregates breakdown. Aggregates disintergration will change the soil pores and thus affect the soil moisture movement. However, there are few studies about the effects of soil internal forces on soil hydraulic properties; and the applicability of the classical water infiltration model considering the interaction forces is still to be further verified. Therefore, in this study, we selected four typical loess parent soils (i.e., Heilu Soil, Loessal Soil, Cinnamon Soil and Lou Soil) as the research object, through the combination of theoretical calculation and experiments, we explored the effect of soil internal force on soil water infiltration. The classical soil water infiltration model and the water characteristic curve model were used to fit the experimental results, and the applicability of the model was verified and compared. The results are as follows:
(1) Quantitatively calculated the distribution characteristics of soil internal forces. Our results show that, with the decrease of electrolyte concentration in bulk solution, the surface potential (absolute value) and surface electric field strength of the four soils increased, and the electrostatic repulsion, DLVO force and net force also increased. The internal forces between the soil particles decreased as the distance between adjacent particles increased. The net force was only attractive at the electrolyte concentration of 1 mol·L-1. The critical potentials of Heilu Soil, Loessal Soil, Cinnamon Soil and Lou Soil were -211.9, -203.6, -223.3 and -232.6 mV, respectively, and the critical concentrations were all 0.01 mol·L-1.
(2) The characteristics of soil water infiltration under different internal forces were systematically studied. Soil internal force had important influence on the process of soil moisture infiltration. With the decrease of electrolyte concentration, the net repulsion between soil particles enhanced, the water infiltration rate and the velocity of wetting front reduced, and the soil moisture accumulation infiltration decreased.
The electrolyte concentration of 0.01 mol·L-1 was the critical concentration for controlling water movement. When the electrolyte concentration is lower than the critical concentration, the parameters such as the water infiltration rate and the migration velocity of wetting front did not change with the electrolyte concentration in bulk solution. Both the Kostiakov model and the Philip model could fit well with the experimental results. Overall, the Kostiakov model was better than Philip model.
(3) The changes of soil water holding capacity under different internal forces were explored. With the decrease of electrolyte concentration, the net repulsion forces increased, and the soil saturated hydraulic conductivity reduced, the soil water holding capacity was enhanced. Both the van Genuchten model and the Gardner model can well fit the water characteristic curves of four soils under different internal forces.Overall, the Gardner model was better than van Genuchten model to fit soil water
characteristic curve.
 

Subject Area环境科学技术 ; 环境工程学 ; 环境工程学其他学科
MOST Discipline Catalogue工学 ; 工学::环境科学与工程(可授工学、理学、农学学位)
Table of Contents
目 录
第 1 章 绪论...............................................................................................1
1.1 选题背景及意义 .................................................................................................1
1.2 国内外研究现状 .................................................................................................2
1.2.1 土壤水分入渗及模拟...................................................................................2
1.2.2 土壤持水性及模拟.......................................................................................4
1.2.3 土壤团聚体稳定性.......................................................................................6
1.2.4 土壤颗粒间内力作用...................................................................................7
1.3 结语 .....................................................................................................................9
第 2 章 研究内容与方法 ........................................................................10
2.1 研究目标 ...........................................................................................................10
2.2 研究内容 ...........................................................................................................10
2.3 技术路线 ...........................................................................................................11
2.4 样品采集与处理 ...............................................................................................11
2.5 试验方法 ...........................................................................................................12
2.5.1 土壤基本理化性质分析.............................................................................12
2.5.2 土壤水分入渗特性测定试验.....................................................................13
2.5.3 饱和导水率测定试验.................................................................................14
2.5.4 水分特征曲线测定试验.............................................................................14
2.6 数据处理与分析 ...............................................................................................15
2.6.1 表面电场、内力作用的计算.....................................................................15
2.6.2 入渗数据拟合模型.....................................................................................17
2.6.3 饱和导水率计算.........................................................................................17
2.6.4 水分特征曲线拟合模型.............................................................................18
第 3 章 土壤颗粒间的内力作用表征 ....................................................19
3.1 土壤颗粒表面电位 ...........................................................................................19
3.2 土壤颗粒表面电场强度分布 ...........................................................................19
3.3 土壤内力作用大小计算 ...................................................................................20
3.3.1 颗粒间的静电斥力.....................................................................................20
3.3.2 颗粒间的范德华力与水合斥力.................................................................22
3.3.3 颗粒间的 DLVO 作用力............................................................................23
3.3.4 颗粒间的净作用力.....................................................................................25
3.4 小结 ...................................................................................................................27
第 4 章 土壤内力作用对水分入渗能力的影响及模拟 ........................29
4.1 土壤内力作用对湿润锋运移速度的影响 .......................................................29
4.2 土壤内力作用对累积入渗量的影响 ...............................................................30
4.3 土壤内力作用对入渗速率的影响 ...................................................................32
4.4 两种入渗模型拟合比较 ...................................................................................33
4.5 小结 ...................................................................................................................36
第 5 章 土壤内力作用对土壤持水性能的影响及模拟 ........................38
5.1 土壤内力作用对饱和导水率及水分特征曲线的影响 ...................................38
5.2 土壤内力作用对当量孔径分布的影响 ...........................................................40
5.3 水分特征曲线模型拟合比较 ...........................................................................42
5.3.1 van Genuchten 模型水分特征曲线模拟 ....................................................42
5.3.2 Gardner 模型水分特征曲线模拟 ...............................................................43
5.3.3 两种水分特征曲线模型拟合比较.............................................................43
5.4 土壤内力作用对持水性的影响 .......................................................................44
5.5 小结 ...................................................................................................................47
第 6 章 总结.............................................................................................49
6.1 主要结论 ...........................................................................................................49
6.2 研究不足与展望 ...............................................................................................50
参考文献...................................................................................................51
致 谢.......................................................................................................59
作者简历及攻读学位期间发表的学术论文与研究成果 ......................61
Pages61
Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8799
Collection水保所2018--届毕业生论文
Recommended Citation
GB/T 7714
杨志花. 土壤内力作用对黄土母质发育土壤水力学性质的影响及模拟[D]. 北京. 中国科学院大学,2019.
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