水库下泄低温水对浅层包气带水热耦合运动的影响机理及径向基函数法模拟

Volumes of low-temperature water present in large reservoirs infiltrated to the two sides of the river will form the lower part of the low-temperature water layer and the upper part of the natural temperature of the surface of the non-isothermal environment of soil; it will bring the re-distribution of temperature field and moisture field, and impact directly the soil near the ecological environment. Theoretical analysis and generalization soil bin test were adopted to study the mechanism of low temperature water from reservoir on the water- heat transport in shallow vadose zone, leading into regularization techniques and meshless radial basis function method and building a numerical model of hydrothermal coupled motion from the spatial structure start. First, based on the measured data, the main factors were identified by analyzing the influence of low temperature water from reservoir on the water- heat transport in shallow vadose zone. The next to build indoor soil test simulation system to study the low-temperature water infiltration under the conditions of internal and external factors of soil temperature field the mechanism of the influence of the water field. Finally, using radial basis function meshless method to create a shallow unsaturated zone under conditions of low temperature water infiltration hydrothermal coupled numerical model of the movement, the introduction of regularization techniques to study and solve the model stability and achieve water the movement of the thermal coupling the meshless numerical simulation. The research results can enrich the basic theory of soil water dynamics and its simulation method and improve the reservoir downstream riparian ecological environment, which have an important academic significance and practical value.

高坝大库的水库低温水，下泄后入渗到河道两岸，会形成下部低温水层和上部天然温度表层的土壤非等温环境，必将带来温度场和水分场的重分布，并直接对临近包气带生态环境产生影响。项目拟采取理论分析和概化土槽试验的方法，研究水库下泄低温水对浅层包气带水热运动的影响机理，并引入正则化技术和无网格径向基函数法，从空间结构入手，构建水热耦合运动的数值模型。首先基于实测资料分析水库低温水下泄对河道两岸土体水热运动的影响，找出主要影响因素，其次构建室内土体试验模拟系统，研究低温水入渗条件下内外因素对土体温度场及水分场的影响机理，最后采用径向基函数无网格法建立低温水入渗条件下浅层包气带水热耦合运动的数值模型，引入正则化技术研究解决模型的稳定性问题，实现水热耦合运动的无网格化数值模拟。研究成果可丰富土壤水动力学基本理论及其模拟方法，并可为进一步研究改善水库下游河岸带生态环境提供理论基础，有着重要的学科意义和实际价值。

高坝大库水电站的发电尾水大多温度较低，水库下泄的低温水入渗到河道两岸后，将对周边环境和生态产生不利的影响。本项目的主要内容是构建低温水入渗土壤水热运移的数学模型，探讨低温水入渗条件下包气带水分、温度动态变化机理。考虑相关自然环境因素，得出了水库下泄低温水入渗条件下土壤水热分布及运移变化的驱动因子，如入渗水温和入渗水头、环境温度和湿度、太阳辐射、土壤自身的物理特性等都是影响土壤温度场和水分场发生变化的重要因素；通过不同外界环境因素变化的概化模型试验数据分析，对水温、水头和辐射温度等外界环境因素与土壤温度场和水分场的内在联系进行了研究，揭示了低温水入渗条件下包气带水分、温度动态变化机理；构建了低温水入渗土壤水热运移的数学模型，并在对模型进行参数率定与模型验证的基础上，模拟分析了不同水头低温水入渗条件下土壤水分、温度动态变化规律；采用局部灵敏度分析方法，将模型中单一参数变化的输出结果与原基值进行比较，确定了影响模型模拟温度场的主要影响因子，并且通过全局灵敏度分析方法分析得出入渗水头H最为敏感，入渗水温T、渗透率Ks、Van Genuchten参数α等参数对温度场影响较显著。该研究成果对合理高效的利用工程或非工程措施来进行水库的泄水温度调节和管理，减缓水库下泄低温水对环境和生态的不利影响，丰富土壤水动力学基本理论有着重要的理论意义和实际应用价值。