适合湿陷性黄土的入渗模型及入渗参数的变化情况研究

发布时间：2018-05-20 03:29

本文选题：湿陷性黄土 + 膨胀性　；参考：《华北水利水电大学》2017年硕士论文

【摘要】：自然界中的水是一个循环的连续整体,其中降雨入渗是水循环中一个重要环节。降雨入渗后到达植物根系,再通过叶片的气孔扩散到静空气层,最后进入大气层,完成自然界水循环过程。在这个过程中,降雨入渗为植物生长和生存提供物质基础,也是植被吸收水分的唯一途径,同时降雨入渗过程也产生土壤水和地表径流。一直以来,土壤水是农业水土问题中重点研究对象之一,对植被种植、节水灌溉、土地荒漠化的治理等方面都起到重要的作用,特别是在黄土地区,湿陷性黄土的膨胀性使土壤水分特征参数发生变化,很大程度上影响着土壤水分入渗过程。本文在对国内外的土壤水入渗过程研究进展整理分析的基础上,设计了湿陷性黄土积水入渗和降雨入渗实验,验证了湿陷性黄土膨胀变形对土壤饱和含水量、饱和导水系数、饱和比容积等参数的影响,在此基础上研究了湿陷性黄土的膨胀变形对土壤水分入渗过程的影响,并采用Philip公式、Kostiakov公式和Horton公式等入渗经验模型拟合分析了土壤水分入渗过程中入渗速率的变化情况,得到了以下结论:(1)分析了湿陷性黄土膨胀后土壤饱和水分运动参数变化,得到了湿陷性黄土降雨入渗过程中相关物理参数的变化过程。入渗过程中,在膨胀力和自重应力作用下,土壤容重随深度增加逐渐增大,饱和含水量逐渐减小且减小速度先快后慢,土壤饱和导水系数也逐渐减小,同时实验结果也为土壤水分入渗模型的拟合提供有力的数据支撑。(2)可以描述湿陷性黄土降雨入渗过程中考虑体积变化的土壤水分入渗经验公式。以入渗速率随时间变化情况为对象,选取Philip公式、Kostiakov公式和Horton公式,拟合得到相关参数值及模型的相关系数,综合考虑拟合公式中参数的实际物理意义,总结出适合膨胀土的土壤水分入渗经验公式。拟合结果中,Philip公式的拟合得到的相关系数较小,因此不适用于湿陷性黄土的入渗过程。Kostiakov公式和Horton公式的相关系数均大于0.9,Kostiakov公式对饱和段拟合结果较为准确,Horton公式对初始入渗和稳定入渗的过程均可以较好拟合,综合考虑其它实际因素,Horton公式是拟合考虑膨胀土体积变化的土壤水分入渗经验公式较为理想的模型。(3)湿陷性黄土体积变化对土壤水分入渗过程的影响。通过分析降雨条件下湿陷性黄土入渗过程中的体积、自重应力、膨胀力和饱和导水系数四个变量随深度的变化关系,总结了体积变化对湿陷性黄土入渗参数的影响及其影响程度。入渗过程中,假设土壤各单位深度的膨胀力不变,自重应力随深度增加逐渐增大,但体积增大量逐渐减小,单位深度处土壤饱和导水系数随深度逐渐减小,因此,湿陷性黄土吸水后体积膨胀对入渗过程具有一定影响。本文阐明了膨胀性黄土体积变化对入渗过程相关参数的影响及其变化趋势,计算了入渗过中土壤孔隙度及饱和导水系数的变化情况,得出了考虑体积变化的膨胀土入渗经验模型,在土壤水分入渗模型的建立、优化及土壤饱和导水系数测量方面都有一定实际意义。
[Abstract]:Water in nature is a continuous and continuous whole, in which rainfall infiltration is an important link in the water cycle. After infiltration of rain, it reaches the plant root, then spreads through the stoma of the leaves to the static air atmosphere, and finally enters the atmosphere to complete the natural water cycle. In this process, rainfall infiltration is the plant growth and survival supply. The quality basis is also the only way to absorb water by vegetation, and the rainfall infiltration process also produces soil water and surface runoff. Soil water has been one of the key research objects in the agricultural and soil problems, which has played an important role in vegetation planting, water saving irrigation and land desertification control, especially in the loess region. The expansibility of the Loess makes the soil water characteristic parameters change and affects the infiltration process of soil water to a great extent. On the basis of the analysis of the progress of soil water infiltration at home and abroad, the experiment of water infiltration and rainfall infiltration in collapsible loess is designed, and the swelling deformation of collapsible loess is verified to be full of soil. On the basis of the influence of water content, saturated hydraulic conductivity, saturation ratio and other parameters, the influence of swelling deformation of collapsible loess on soil water infiltration is studied. The infiltration rate changes in soil water infiltration process are fitted and analyzed by Philip formula, Kostiakov formula and Horton formula. The following conclusions are obtained: (1) the variation of soil saturated water movement parameters after the collapsible loess expansion is analyzed, and the change process of the related physical parameters in the rainfall infiltration process of collapsible loess is obtained. In the process of infiltration, the soil bulk density increases with the depth, and the saturated water content gradually decreases with the action of expansion and weight stress. At the same time, the soil moisture permeability coefficient is gradually reduced, and the experimental results also provide powerful data support for the fitting of soil water infiltration model. (2) the empirical formula of soil moisture infiltration in the process of collapsible loess rainfall infiltration is described. The Philip formula, the Kostiakov formula and the Horton formula are selected to fit the correlation coefficient of the relative parameters and the model, and the actual physical meaning of the parameters in the fitting formula is taken into consideration. The empirical formula of soil water infiltration suitable for expansive soil is summed up. The fitting result is not suitable for the correlation coefficient of the fitting of the Philip formula. The correlation coefficient of.Kostiakov formula and Horton formula in the infiltration process of collapsible loess is more than 0.9, and the result of the Kostiakov formula is more accurate. The Horton formula can fit well the initial infiltration and the stable infiltration process, and the other practical factors are considered synthetically. The Horton formula is the soil which considers the volume change of the expansive soil. The empirical formula of soil water infiltration is an ideal model. (3) the effect of the volume change of collapsible loess on the infiltration process of soil water. Through the analysis of the volume, self weight stress, expansion force and saturated conductivity of four variables with the depth of the collapsible loess infiltration under rainfall conditions, the volume change to the collapsible yellow is summed up. The influence of soil infiltration parameters and its influence degree. In the process of infiltration, it is assumed that the expansion force of the soil depth is constant, and the weight stress increases gradually with the depth, but the volume increases gradually, and the soil saturated water conductivity coefficient decreases with the depth at the unit depth. Therefore, the volume expansion of the collapsible loess after water absorption is used in the infiltration process. The influence of the volume change of expansive loess on the related parameters of infiltration process and the change trend are clarified in this paper. The change of soil porosity and saturated conductivity of saturated soil is calculated, and the empirical model of expansive soil infiltration considering the volume change is obtained, and the establishment of soil water infiltration model, optimization and soil satiety are obtained. And the measurement of water conductivity coefficient has certain practical significance.
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S152.7

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