【作者】 李贺丽；

【导师】 李怀恩； 史文娟；

【作者基本信息】 西安理工大学 ， 环境工程， 2007， 硕士

【摘要】 本文结合陕西省重点实验室访问学者专项计划项目，采用粗颗粒石英砂、细颗粒石英砂和西峰土三种性质不同的土壤介质开展有关水分连续供给的下渗过程、非充分水分再分布过程以及充分水分再分布过程等不同水分运移过程中指流的形成与发展实验研究。研究充分考虑了不同因素对指流形成与发育过程的影响，旨在揭示和掌握不同水分运移过程、不同土壤结构、不同施水条件、不同流体特性以及不同初始／边界条件下有关指流形成与发展的基本规律，从而为充实指流理论及指导生产实践提供必要的科学依据。论文在充分了解国内外指流研究成果的基础上，通过进行大量的系统的室内实验及对实验数据的分析处理，取得了如下主要研究成果：1、均质结构的土壤中，在连续供给水分的下渗过程、非充分水分再分布过程及充分水分再分布过程中，湿润锋的不稳定性普遍存在；一定的条件下，这种不稳性都可以发展成为指流。2、供水强度对指流发育产生的或促进或抑制的影响都是限定在一定的范围之内：当供水强度过小或过大时，湿润锋都更易趋于呈现出稳定形式，指流都不易出现。3、通过对不同的水分运移过程进行研究，结果表明土壤质地对指流发育过程产生的影响是一致的，即普遍条件下，质地较粗的土壤介质中都更易于形成指流。4、不同水分运移过程中，初始含水量的增大对指流的形态发育产生的影响均为抑制作用；但锋面的下移速度由于受指流的形态发育情况及初始含水量的双重影响，其大小变化不与其中任一因素具有单增或单减关系，是二者共同影响的结果。5、对于所研究的2种水分运移过程，质地成层（上细下粗）的土壤结构都有利于指流的形成和发展；湿度成层（上千下湿）的土壤结构能够促进连续)供给水分的下渗过程及非充分水分再分布过程中指流的发育，然而这种促进作用十分有限，影响不大；而对于前期水分下渗时土表存在积水的充分水分再分布过程，湿度成层的土壤结构对指流发育产生的影响则呈现出抑制作用。6、一定范围内，前期下渗过程中施加水量的增加对非充分水分再分布过程中指流的形态发育及进程能够产生明显的促进作用；而在充分供水条件下，其对水分再分布过程结束时指流最终的发育形态影响不大，但能够促进指流的发育进程。7、在土壤介质及其他条件一致的情况下，在充分供水之后的水分再分布过程中，对于成分单一的KNO₃溶液来说，所施加溶液的浓度越大时，指流的发育速度越快，指流的形态越明显。8、与采用浓度为7214mg／l的单一的硝酸钾（KNO₃）溶液相比，在其他条件均一致的情况下，当采用密度较小、而所含离子或化合物种类较多的自来水作为流体进行实验时，指流的发育情况更为明显。更多还原

【Abstract】 This paper was supported by Project about Colleges and Universities Key Laboratory Visited Scholar Plan in Shannxi province. The experiments were designed for two different water transmission processes including the water infiltration process with continuous water supply and the water redistribution process with insufficient or sufficient water supply. Three different soils (a coarser sand, a finer sand and a Xifeng soil of Gansu province) were used in the experiments. The effect factors included the structure and the texture of soil, the conditions of the water supply, the fluid characteristics and the initial/boundary conditions. With a purpose to disclose the basic laws of the finger flow, enrich the theory of finger flow research and provide practical guidance, the characteristics and the effects of different factors on the development of finger flow were studied during the research. Based on extensive review on finger flow research achievements from domestic and abroad, then through the systematic experiments indoors as well as the processing and analyzing of the experimental data, the major results are as follows:1. The wetting front instability exists in both processes of water transmission including the water infiltration process with continuous water supply and the water redistribution process with insufficient or sufficient water supply, and can grow into finger flow under certain conditions.2. Varying the intensity of water supply within certain extents can bring both positive and negative effects on the development of finger flow, and when the intensity of water supply is too high or too low, the wetting front always tends to be stable.3. During the two different water transmission processes studied in this paper, the effect of soil texture on the development of finger flow is similar, that is, finger flow always tends to occur in coarser-texture soil.4. During both the water infiltration and the water redistribution process, high initial water content always has disadvantageous effects on the development of finger flow. The underdeveloped finger flow is wider and slower the downward movement of the wetting front while the high initial water content accelerates it. So the speed of the wetting front is affected by both the form of underdeveloped finger flow and the magnitude of the initial moisture content, and its varying trend is undefined.5. The layered structure of soil may results from the difference of soil texture and humidity. In the texture-layered soil (a coarser-texture sublayer), the ringer flow is promoted in both the water transmission processes. The humidity-layered soil structure (a wetter-soil sublayer) has negative effect on the development of finger flow in the water redistribution process with sufficient water supply and positive effect on it in the water infiltration process with continuous water supply and in the water redistribution process with insufficient water supply; however, the positive effect is very limited and unconspicuous.6. To some extent, increasing the quantity of water supplied in prior process of infiltration can act as an obvious stimulus to the form and speed of the finger flow development in the water redistribution process with insufficient water supply. In the water redistribution process with sufficient water supply, the quantity of water increased in prior process of infiltration has little influence on the final form of finger flow developed, whereas quickens the speed of the finger flow development.7. With the same soil and other factors, considering the simplex solute (KN03) dissolved in distilled water, the finger flow develops faster with its form clearer if more solute (KN03) is added in the water redistribution process with sufficient water supply.8. Keeping other factors the same, compared with the experiment aforementioned in which the KN03 solution concentration is 7214mg/l (max.) in distilled water, the finger flow tends to occur more easily in the experiment in which tap water is used, which is of Low-density and consisted of various kinds of ions or compounds.Fund of Project: Project about Colleges and Universities Key Laboratory Visited Scholar Plan in Shannxi Province.更多还原