【作者】 李勇；

【导师】 刘佩贵； 李伟；

【作者基本信息】 合肥工业大学 ， 水利工程（专业学位）， 2022， 硕士

【摘要】 为了探讨潜水矿化度对不同粒径、不同土壤类型毛细水上升高度的影响机制与影响范围,剖析毛细水上升速率变化特征,分析矿化度对生态水位的影响,为科学确定地下水生态水位、有效治理土壤盐渍化问题提供理论支撑。本文设计了一套室内试验装置进行了土柱试验,并与数值模拟相结合研究了矿化度的影响阈值,并在新疆巴什拉克地区进行了与生态水位有关的实际应用。首先通过构建毛细水上升物理试验模型,开展了不同矿化度、不同土壤类型下的毛细水上升试验。试验定量刻画了粒径与矿化度对毛细水上升高度的差异,分析了毛细水的上升速率特征,并对矿化度与毛细水上升高度关系进行了拟合。试验结果表明,矿化度通过改变土壤水的重力势、基质势来制约毛细水的上升高度;毛细水上升速率变化呈矿化度增大,初期上升速率随之增大,同时衰减越快的特征。粉砂和砂质壤土由于粒径小、土壤结构复杂,毛细水速率波动变化较大;全试验周期内毛细水上升高度h与时间t可用3参数对数函数刻画。其次,针对室内试验未解决的矿化度阈值问题,本文使用HYDRUS-1D软件进行了土壤含水量与Cl~-浓度随高度变化特征模拟与验证。基于“室内试验+数值模拟”的方法,综合考虑土壤含水量随时间和埋深的变化情况,确定了中砂、细砂和粉砂的矿化度阈值分别为5～75g/L、3～35g/L、1～35g/L,并对阈值的合理性进行了分析与讨论。最后,以新疆巴什拉克地区为研究区,将本文确定的矿化度阈值在生态水位确定方面进行了应用。矿化度阈值对生态水位的影响主要体现在水位上限,原因是水位上限包含了毛细水上升高度,矿化度阈值通过影响毛细水上升高度进而影响到生态水位上限。分析表明,基于矿化度阈值影响的生态水位上限为3.735m,相较于淡水条件下的3m水位上限降低了0.735m,下降量体现了矿化度阈值对毛细水上升高度的影响。更多还原

【Abstract】 In order to explore the influence mechanism and scope of total dissolved solids(TDS)on capillary water rising height of different particle sizes and different soil types,the variation characteristics of capillary water rising rate were analyzed,and the influence of TDS on ecological water level was analyzed.It provides theoretical support for scientifically determining groundwater ecological water level and effectively controlling soil salinization.In this paper,an indoor test device was designed for soil column test,and the influence threshold of TDS was studied by combining with numerical simulation,and the practical application related to ecological water level was carried out in Basraq,Xinjiang.Firstly,by constructing the physical test model of capillary water rise,the capillary water rise tests under different TDS and different soil types were carried out.The difference of capillary water rising height between particle size and TDS was quantitatively characterized,and the rising rate characteristics of capillary water were analyzed.The relationship between TDS and capillary water rising height was fitted.The experimental results show that TDS restricts the rising height of capillary water by changing the gravity potential and matrix potential of soil water;The change of capillary water rise rate is characterized by the increase of TDS,the increase of initial rise rate and the faster attenuation.Fluctuation of capillary water rate in silt and sandy loam due to small particle size and complex soil structure.The rise height(h)and time(t)of capillary water in the whole test period can be described by three-parameter logarithmic function.Secondly,aiming at the problem of TDS threshold that has not been solved in the laboratory test,this paper uses HYDRUS-1D software to simulate and verify the variation characteristics of soil water content and Cl~-concentration with height.Based on the method of“indoor test+numerical simulation”,considering the variation of soil moisture with time and burial depth,the TDS thresholds of medium sand,fine sand and silt were determined as 5～75 g/L,3～35 g/L and 1～35 g/L respectively,and the rationality of the thresholds was analyzed and discussed.Finally,the TDS threshold determined in this paper is applied to the determination of ecological water level in Bashrak region of Xinjiang.The influence of TDS threshold on ecological water level is mainly reflected in the upper limit of water level,because the upper limit of water level includes the rise height of capillary water.The TDS threshold affects the upper limit of ecological water level by affecting the rise height of capillary water.The analysis shows that the upper limit of ecological water level based on the influence of TDS threshold is 3.735m,which is 0.735m lower than the upper limit of 3 m water level under freshwater condition.The decrease reflects the influence of TDS threshold on the rise height of capillary water.更多还原