季节性河道非饱和带现场入渗试验及室内试验数值模拟研究

发布时间：2018-01-01 05:41

本文关键词：季节性河道非饱和带现场入渗试验及室内试验数值模拟研究　出处：《青岛理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：中国北方大部分地区人口众多,生产生活用水量大,人均水资源量极度短缺,属于干旱半干旱地区。季节性河流在干旱半干旱地区普遍存在。大沽河是青岛市主要水源地,属于季节性河流。季节性河流汛期河水暴涨暴落与河道渗漏息息相关。研究大沽河渗漏情况,为进一步研究其过水流量与地下水位时空关系,进而为大沽河流域水资源管理提供科学依据,同时也为其他季节性河流水域管理提供借鉴。本文以大沽河为研究对象。首先对大沽河流域气象、水文、地质、地貌等进行调查。其次通过室内试验对砂样的颗粒级配、干容重、土粒密度、孔隙度以及渗透系数进行测定。通过勘查大沽河干流上、中、下游河床,分别选择三个具有代表性的野外试验场,分别进行一维垂向非饱和入渗和二维侧向非饱和入渗试验,并分析总结土壤水分运移的规律。最后,利用FEFLOW软件对室内一维垂向非饱和入渗和二维侧向非饱和入渗过程进行模拟,通过模拟值和实测值对比,验证该模型的合理性。论文研究主要取得了以下结论:(1)分别对选定三个野外试验场砂样的颗粒级配分析,得出上、中、下游砂样分别为粗砂、中砂和细沙,并对其干容重、土粒密度、孔隙度以及渗透系数进行测定。(2)在选定的三个野外试验场中,每个试验场分别进行两组定水头包气带一维垂向入渗试验,通过对比分析得出入渗试验中同一试验场相同深度初始含水率越小,入渗速率越快,入渗水流到达传感器的时间越短;同一试验场随着深度的增加,含水率变化依次减慢且达到饱和的时间变长;相同深度砂层初始含水率相近时,上、中、下游砂层水分入渗速率依次减小;整体来看,当同一试验场砂样各层初始含水率之和相近时,各层之间初始含水率差距越小,达到稳定入渗的时间越短。(3)在选定的三个野外试验场中,每个试验场分别进行两组定水头包气带二维侧向入渗试验,通过对比分析得出同一试验场地相同深度初始含水率越小,入渗速率越快,入渗水流到达传感器的时间越短;相同深度砂层初始含水率相近时,上、中、下游砂层水分入渗速率依次减小;整体来看,当同一试验场砂样各层初始含水率之和相近时,各层之间初始含水率差距越小,达到稳定入渗的时间越短。(4)运用地下水数值模拟软件FEFLOW对室内一维和二维包气带入渗过程模拟,将模拟值与实测值进行对比分析,结果表明模拟值与实际值基本吻合,进而得出该模型基本合理,FEFLOW模拟包气带水分运移是可行的,并为整个大沽河流域的包气带水分运动模拟提供参考。
[Abstract]:Most of northern China has a large population, a large amount of water for production and living, and an extreme shortage of water resources per capita. It belongs to arid and semi-arid areas. Seasonal rivers are prevalent in arid and semi-arid areas. Dagu River is the main source of water in Qingdao. It is a seasonal river. The surge and fall of seasonal river in flood season are closely related to river leakage. The leakage of Dagu River is studied in order to further study the temporal and spatial relationship between water flow and groundwater level. Then it provides scientific basis for the management of water resources in Dagu River basin and also provides reference for the management of other seasonal rivers. This paper takes the Dagu River as the research object. Firstly, the meteorological, hydrological and geological aspects of the Dagu River basin are studied. Secondly, the grain gradation, dry bulk density, soil particle density, porosity and permeability coefficient of sand samples were measured through laboratory tests. Three representative field test sites were selected to carry out one dimensional vertical unsaturated infiltration and two dimensional lateral unsaturated infiltration respectively, and to analyze and summarize the law of soil water migration. The one-dimensional vertical unsaturated infiltration and two-dimensional lateral unsaturated infiltration were simulated by FEFLOW software, and the simulated values were compared with the measured values. To verify the rationality of the model. The following conclusions are obtained in this paper: 1) the grain gradation analysis of sand samples selected from three field test sites shows that the upper, middle and lower sand samples are respectively coarse sand. The dry bulk density, soil particle density, porosity and permeability coefficient of sand and fine sand are measured in three selected field test sites. Two groups of one dimensional vertical infiltration tests were carried out in each test site, and the results showed that the smaller initial water content at the same depth in the same test site, the faster the infiltration rate. The shorter the time to reach the sensor is; With the increase of depth, the change of water content in the same test site slows down in turn and the time to saturation becomes longer. When the initial water content of the same depth sand layer is similar, the water infiltration rate of the upper, middle and lower sand beds decreases in turn. As a whole, when the sum of the initial water content of each layer of sand samples in the same test site is similar, the difference of initial water content between the layers is smaller, and the time to achieve stable infiltration is shorter. 3) in the selected three field test sites. Two groups of constant water head aeration zone two dimensional lateral infiltration tests were carried out in each test site. The comparison and analysis showed that the smaller the initial water content at the same depth, the faster the infiltration rate of the same test site. The shorter the time to reach the sensor is; When the initial water content of the same depth sand layer is similar, the water infiltration rate of the upper, middle and lower sand beds decreases in turn. As a whole, when the sum of the initial water content of each layer of sand samples in the same test ground is similar, the difference between the initial water content of each layer is smaller. The shorter the time of stable infiltration is, the shorter the groundwater numerical simulation software FEFLOW is used to simulate the infiltration process of indoor one-dimensional and two-dimensional aeration, and the simulated value is compared with the measured value. The results show that the simulated values are in good agreement with the actual values, and it is feasible to simulate the moisture migration in the aeration zone by FEFLOW. It also provides a reference for the simulation of water movement in the whole Dagu River basin.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TV223

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