【作者】 詹红丽；

【导师】 张展羽；

【作者基本信息】 河海大学 ， 水利水电工程， 2005， 博士

【摘要】 圩区堤防防渗加固技术能有效地阻隔汛期外河水位的堤基滲透,减少管涌、流土和散浸等堤防隐患。但由于某些堤段地下水水流通道被截断,形成了(准)封闭圩区,使圩内外地下水不能自由交换。若干年以后,可能会加重农田渍害和次生沼泽化影响;同时,由于土壤中肥料、农药、盐分的淋溶而在地下水中不断积聚,可能会引起地下水水质变化,给区域生态环境带来不利影响。 本文首先考虑到由于(准)封闭圩区地下水动态受多种因素(如大气降水、蒸发、地表水、人为因素等)的影响,地下水动态具有周期性、趋势性和随机性,故文中借助随机理论及时间序列理论,对上述动态因素建立相应的随机(时间序列)模型。接着,将圩区内河道等数值化,综合考虑各种边界条件,在上述模型的基础上建立通用的圩区水环境模拟及治理规划随机模型。针对圩区堤防防渗工程实际,推导出与堤防封闭率有关的第二类水头边界条件的具体计算表达式。其中详细阐释了对流项、弥散项(其中包括弥散机制和弥散系数的确定)、汇/源项、化学反应项;并分析相应的初始条件和特殊边界条件,以地下水动力学模型为基础,将边界条件、降水入渗、农田腾发和地表水等作为随机时间序列建立预测模型,从而提高模型预测的可靠性。然后,对文中所建立的封闭截渗圩区水环境模拟及治理规划随机模型寻求合理的求解方法并研究其数值的具体实现问题。对于文中拟采用的三阶TVD方法提出了一种改进的浓度指标实时控制新方法,以避免求解过程中可能出现的非物理扰动问题。最后,将文中所建立的随机模型应用于江西省赣东圩区,通过模拟计算与分析,给出该区不同封闭率条件下的地下水水位变化与水质变化情况;提出在现有封闭率0.75情况下,赣东圩区的污染物合理排放量等工程规划指标,成果可为当地水利工程规划与管理提供决策参考。 论文的结尾部分对所取得的成果进行了扼要总结,并提出今后进一步研究的方向。更多还原

【Abstract】 Vertical cut-off wall are often used to reinforce dikes for preventing seepage through bases when polder training is conducted. And usually the wall reaches to the aquifuge. This hydrotechnic can prevent dike base seepage effectively, decrease the piping, soil losing, soaking, dipping, swamping and other hidden troubles. But once the technique is adopted, the flow pathes of ground water will be truncated, and thus a new closed polder come into being. Here the ground water inside and outside of the polder can not exchange freely, so several years later, the dipping and swamping in the farmland may be aggravated. Meanwhile, the eluviating of the fertilizer, the pesticide and the salinity in the soil will result in the accumulation of contamination and even result in the deterioration of the quality of ground water, and bring bad influence to regional environment.In this dissertation, first, considering the groundwater regime in a closed polder is influenced by various factors(e.g. precipitation, evaporation, surface water, etc.), which determines that the groundwater regime bears periodicity, trend and randomicity; therefore, the corresponding random(time series) model is established for the above random factors by dint of random theory and time series theory. And then, by evaluating various boundary conditions synthetically, a universal random model for water environment simulation and training on closed polders is established. Advection, dispersion, sink/source and chemical reactions are discussed and studied carefully in this part. Next, the solution techniques and numerical implementation to the above universal random model is explored. Finally, the model established in this dissertation is applied to JIANGXI GANDONG polder. After calculation, simulation and analysis, the following results are educed: the vary trend of ground water level and ground water quality under different close rate in the studied area and feasible recharge of contaminations. The results will offer a guidance on the water conservancy engineering and the corresponding administration for the similar regions.At the end of this dissertation, conclusions and research tendency in the field of water environment simulation and training on closed polders is summarized briefly.更多还原