基于电法泉州湾海水入侵规律试验研究

发布时间：2018-04-11 22:28

本文选题：电法 + 海水入侵　；参考：《华侨大学》2014年硕士论文

【摘要】：随着沿海城市日新月异的发展，人类赖以生存的地下水资源遭到过度开采，致使沿海地区均有不同程度的海水入侵现象发生，这样便使得本就缺乏的淡水资源受到海水的污染。因此，对海水入侵的规律进行深入研究，并在此基础上提出防治措施，已迫在眉睫。本文在广泛阅读国内外关于海水入侵的研究成果基础上，总结前人所用研究方法和工具的优缺点，确定本文采用室外测试、室内试验和数值模拟相结合的综合研究方法。首先对海水入侵标准的进行了对比探讨，确定室外测量使用井水电导率作为判别指标，并将标准初步定为1700us；而室内试验利用土体的电阻率作为判别指标，分别将砂土和粘土的判别标准确定为50·m和20·m。根据所确定的指标测试研究了泉州湾典型区域海水入侵的现状，并绘制了海水入侵现状图。其次应用高密度电法完成室内海水入侵试验，定量地研究了完整潮汐作用下海水入侵的规律，得到砂-粘土夹层中海水入侵的规律：①随着潮涨潮落，海水先发生入侵而后开始发生回退现象；②砂土层中海水入侵的速度大于粘土层，同层砂土中不同深度各点海水入侵程度不同；③海水入侵具有累积效应，，第二次潮汐海水入侵的程度大于第一次潮汐。然后通过数值模拟对试验进行了一定的弥补，进一步探讨了土体各个因素对海水入侵结果的影响，确定影响海水入侵距离的因素为土体饱和导水率、体积含水率、弥散系数和扩散系数，其中扩散系数是影响入侵的最主要因素，而饱和导水率和弥散系数为影响入侵的重要因素，相对于其他因素而言，土体饱和体积含水率对入侵距离的影响较小，不属于主要因素；数值模拟结果表明：水位差对海水入侵的速度也有一定的影响，水位差的绝对值越大，其发生海水入侵或海水回退的速度越大，处于海平面及淡水水位以下的土层，发生海水入侵速度较快，但其回退速度也快，处于海平面以上，淡水水位以下的土层发生海水入侵容易，但回退相对较难。最后利用建立海水入侵数值模型，对真实地层下泉州湾典型区域未来三年海水入侵程度进行了数值模拟，预测海水入侵的变化规律，为泉州湾海水入侵的防治工作提供指导。
[Abstract]:With the rapid development of coastal cities, the groundwater resources on which human beings depend for survival have been overexploited, resulting in different degrees of seawater intrusion in coastal areas, which makes the freshwater resources that are scarce are polluted by sea water.Therefore, it is urgent to study the law of seawater intrusion and put forward the prevention and cure measures.On the basis of extensive reading of the domestic and foreign research achievements on seawater intrusion, this paper summarizes the advantages and disadvantages of the research methods and tools used by the predecessors, and determines that this paper adopts a comprehensive research method which combines outdoor test, indoor test and numerical simulation.Firstly, the seawater intrusion standard is compared and discussed, and the well water conductivity is determined as the discriminant index for outdoor measurement, and the standard is preliminarily determined as 1700us.However, the resistivity of soil is used as the discriminant index in indoor test.The discriminant criteria of sand and clay are determined to be 50 m and 20 m respectively.The present situation of seawater intrusion in typical area of Quanzhou Bay was studied according to the determined indexes, and the current situation map of seawater intrusion was drawn.Secondly, the indoor seawater intrusion test was completed by using high-density electric method, and the law of seawater intrusion under the action of complete tide was quantitatively studied. The rule of seawater intrusion in sand and clay intercalation was obtained, and the law of seawater intrusion in sand and clay intercalation was obtained with the tide rising and falling.The seawater intrusion in sand layer is faster than that in clay layer, and the seawater intrusion degree is different at different depth in the same layer sand soil.The second tidal intrusion is greater than the first tidal intrusion.Then the experiment is compensated by numerical simulation, and the influence of various soil factors on the result of seawater intrusion is further discussed. The factors that affect the distance of seawater intrusion are the saturated water conductivity of soil and the volume water content.Diffusion coefficient and diffusion coefficient, among which diffusion coefficient is the most important factor, saturation water conductivity and diffusion coefficient are important factors affecting invasion, compared with other factors,The numerical simulation results show that the difference of water level has a certain influence on the velocity of seawater intrusion, and the absolute value of the difference of water level is larger.The higher the speed of seawater intrusion or seawater retrogression is, the faster the seawater intrusion occurs in the soil layer below sea level and fresh water level, but the faster the return speed is above sea level.Seawater intrusion is easy to occur in the soil layer below the fresh water level, but it is relatively difficult to retreat.At last, a numerical model of seawater intrusion is established to simulate the degree of seawater intrusion in the typical area of Quanzhou Bay in the next three years, to predict the variation of seawater intrusion, and to provide guidance for the prevention and treatment of seawater intrusion in Quanzhou Bay.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.2

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