LNAPL在包气带形成的透镜体形状及水位波动对其的影响

发布时间：2018-02-26 12:56

本文关键词： 轻非水相液体饱和度-压力曲线透镜体水位波动　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：轻非水相液体(LNAPL)泄漏进入到地下环境中,首先在包气带中进行垂向迁移,到达毛细带后在地下水面以上形成饱和透镜体?准确预测LNAPL渗漏在包气带形成的透镜体厚度,对于LNAPL的去除及污染含水层的修复,具有重要的指导意义。地下水位会随着季节的变化而变化,而漂浮在水位线上的透镜体也会随之变化,因此在预测LNAPL的泄漏时应将透镜体随着水位波动的变化情况考虑在内。本文通过LNAPL进入包气带后形成的透镜体各点在垂向上的受力平衡分析,得出了一个用LNAPL和水直接的两个进入压力来预测LNAPL在平衡时形成的透镜体厚度的公式。并利用土-水特征曲线的滞后作用,用一种简单的室内实验获得了水作为润湿相,柴油作为非润湿相时,在中砂和粗砂中含水量和基质吸力的关系,并分别用Brooks-Corey模型(BC模型)、Van Genuchten模型(VG模型)以及Fredlund-Xing模型(FX模型)进行拟合,得出预测的透镜体厚度。再通过两组模拟槽实验进行柴油进入包气带后的迁移模拟,测出平衡时水位线上的透镜体厚度,并跟预测的厚度进行比较。最后进行了几组水位波动的模拟槽实验,再通过取样,用GB260-77的方法测出不同位置上的含水率和含油率的变化情况,对比在水位波动下的透镜体变化情况。本文主要得出了以下结论:(1)用油-水间的脱湿吸湿进入压力来预测LNAPL在包气带形成的透镜体厚度的方法具有一定的可行性。且在拟合土-水特征曲线时,VG模型比BC模型更加准确。(2)用本文方法预测透镜体厚度时,与模拟槽中观测到的透镜体厚度相比偏小,实验误差的原因一部分是因为无法得出完全干燥的吸湿脱湿曲线,造成预测值偏小。一部分可能是因为观测到的透镜体厚度偏大。(3)在最终形成的透镜体处,油的饱和度随着柴油的迁移锋面越来越大,水和气的饱和度随着柴油的迁移锋面越来越小。油的饱和度在透镜体中的分布规律为从中间到两侧逐渐降低,随着迁移锋面越来越高。(4)在水位不变、水位下降两种情况下,柴油在介质中优先驱替了水;在水位上升的情况下,柴油在介质中优先驱替了气。
[Abstract]:Light non-aqueous phase liquid (LNAPL) leak into the underground environment, first in the vadose zone of vertical migration, reaching the capillary zone after the formation of saturated lens in the ground above the water surface? Accurate prediction of LNAPL leakage in the lens thickness of the vadose zone formed, for removal of LNAPL dye and repair sewage aquifer. It has important guiding significance. The groundwater level will change with the seasons, lens and floating in the water level line will also change, so the leakage prediction of LNAPL should be considered as the lens changes, the fluctuation of water level. In this paper, LNAPL into the vadose zone after the lens to force balance analysis in vertical, obtained a LNAPL and two water directly into the pressure to predict the lens thickness LNAPL is formed in the balance of the formula. And the hysteresis of soil water characteristic curve, with a The indoor experiment to obtain a simple water as the wetting phase, diesel as a non wetting phase, the relationship in the medium sand and coarse sand water content and matrix suction, and respectively by the Brooks-Corey model (BC model), Van model (Genuchten VG model) and Fredlund-Xing model (FX model) were fitted that lens thickness prediction. By two simulation experiments of diesel oil into the tank group migration after simulation, lens thickness measured water level line balance, and to predict the thickness were compared. Finally, the simulation experiment of several groups of tank water level fluctuation, and through sampling, using GB260-77 method to detect changes in different positions the moisture and oil content, contrast lens changes in the water level fluctuation condition. This paper draws the following conclusions: (1) the oil - water between the dehumidified moisture into the pressure to predict LNAPL in vadose zone formation Methods lens thickness is feasible. And in the soil water characteristic curve, VG model is more accurate than the BC model. (2) predict the lens thickness using this method, compared with the lens thickness of simulated slot observed in small, because the experimental error is partly because unable to draw completely dry moisture absorption and desorption curves, resulting in predictive value is too small. A part may be because the lens thickness observed is too large. (3) in the final form of the lens body, oil saturation with diesel oil migration front is more and more big, gas and water saturation with diesel oil migration front more and more small. The distribution of oil saturation in the lens is decreased gradually from the middle to both sides, with the migration front more and more high. (4) the water level constant, water level dropped two, diesel in the medium priority flooding water; in the water level rise situation At the same time, the diesel fuel in the medium gives priority to the gas.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X523

【相似文献】