干旱区平原水库渗流计算及周边盐渍化预测分析

发布时间：2018-03-20 10:30

本文选题：平原水库　切入点：ABAQUS　出处：《新疆农业大学》2014年硕士论文　论文类型：学位论文

【摘要】：在内陆干旱区修建平原水库能有效地缓解区域性缺水的问题，但由于水库坝线长，渗漏较山区水库更为严重，容易抬高下游地下水位，水库周边的地下水位便成为了影响土地生态环境的敏感因素。本文以坐落在半荒漠地区的新疆某大型平原水库为研究对象，针对可能出现的土壤盐渍化问题，用ABAQUS软件模拟计算水库渗漏后的下游地下水埋深，分析了水库周下游可能出现的土壤盐渍化的程度和范围，并研究典型的恰拉水库，探讨防治平原水库周边土壤盐渍化的措施。初步成果如下：（1）利用ABAQUS模拟水库典型断面不同工况的坝体、坝基以及下游土壤中水的渗流历时形态，结果发现：在库水位为495m的实际情况下，渗流较为缓慢，，预测水库开始运行75年后水库渗漏对下游地下水的影响会达到极限，距坝趾200m处观测点的地下水埋深由初始的10.48m上升至1.45m，距坝趾400m处观测点的地下水埋深由初始的10.60m上升至2.15m；在库水位为500m的最不利情况下：渗流速度比前一工况下有所加快，预测水库运行至40年时水库渗漏对下游地下水的影响会达到稳定状态，此时距坝趾200m处观测点的地下水埋深由初始的10.48m上升至1.25m，距坝趾400m处观测点的地下水埋深由10.60m上升至1.95m，随后会轻微上下波动。（2）地下水临界深度是判别是否会出现土壤盐渍化现象的标准，经分析得知适用于水库下游的地下水临界深度为2.85m。（3）针对可能出现的土壤盐渍化现象，由计算所得的典型断面处的地下水埋深历时数据，对比地下水临界深度，可预测水库下游可能出现的盐渍化情况，结果表明：1）在实际情况下，水库蓄水后，地下水埋深正好是临界地下水深（2.85m）的位置不断向远处移动，75年后趋于稳定，2095年时的盐渍化的范围最远，达到距离坝趾609m处；2）最不利情况下，由于渗流速度较大，地下水水位上升快，到2045年时渗流达到稳定状态。（4）分析计算所得的典型断面处不同时间点的地下水埋深，可得出水库渗漏补给区的范围，结果表明：1）水库上游水位为495m的实际情况下，水库渗漏补给区的边界由初始的距坝趾300m的位置向大坝下游方向移动，到了水库蓄水后的第75年即2082年，渗漏补给区边界的移动趋于稳定；2）水库上游水位为500m的最不利情况下，水库渗漏补给区的边界由初始的距坝趾300m的位置向大坝下游方向移动，到了水库蓄水后的第40年即2045年，渗漏补给区边界的移动趋于稳定。（5）对恰拉水库改善防渗措施前后的分析结果说明，完善坝体坝基的防渗措施对防治水库周边土壤盐渍化效果明显。
[Abstract]:The construction of plain reservoirs in inland arid areas can effectively alleviate the problem of regional water shortage. However, because of the long dam line, the leakage is more serious than that of mountain reservoirs, and it is easy to raise the downstream groundwater level. The groundwater level around the reservoir has become a sensitive factor affecting the land ecological environment. In this paper, a large plain reservoir located in the semi-desert area of Xinjiang is taken as the research object, aiming at the problem of soil salinization that may occur. Using ABAQUS software to simulate and calculate the groundwater depth of the lower reaches after reservoir leakage, to analyze the degree and scope of soil salinization that may occur in the lower reaches of the reservoir, and to study the typical Chara reservoir. The measures to prevent and cure soil salinization around plain reservoirs are discussed. The preliminary results are as follows:. 1) using ABAQUS to simulate the percolation duration of dam body, dam foundation and downstream soil of typical section of reservoir under different working conditions. The results show that the seepage flow is slow when the water level of reservoir is 495m. It is predicted that the effect of reservoir leakage on the downstream groundwater will reach its limit after 75 years of operation. The groundwater depth at the observation point 200m from the dam toe increased from 10.48m to 1.45m, and the groundwater depth at the observation point 400m from the dam toe increased from 10.60m to 2.15m.The percolation velocity was accelerated when the water level of the reservoir was 500m. It is predicted that the effect of reservoir leakage on the downstream groundwater will reach a stable state when the reservoir runs for 40 years. The groundwater depth at the observation point 200m from the dam toe increases from 10.48m to 1.25m, and the groundwater depth at the observation point 400m from the dam toe increases from 10.60m to 1.95m. then it fluctuates slightly up and down. 2) the critical depth of groundwater is the criterion to judge whether soil salinization will occur, and the critical depth of groundwater suitable for the lower reaches of reservoir is 2.85 m. (3) in view of the possible soil salinization phenomenon, the groundwater salinization in the lower reaches of the reservoir can be predicted by comparing the groundwater critical depth with the calculated groundwater depth data at the typical section. The results show that, in practice, after the reservoir impoundments, the groundwater depth is exactly 2.85 m) and the position of the groundwater is moving to a distance, which tends to stabilize after 75 years, and the salinization range in 2095 is the furthest. Under the most disadvantageous condition, the groundwater level rises quickly because of the large seepage velocity, and the seepage reaches a stable state by 2045. 4) the depth of groundwater buried at different time points at the typical section is analyzed and calculated, and the range of reservoir leakage and recharge area can be obtained. The result shows that the upstream water level of the reservoir is 495m. The boundary of the leakage recharge area of the reservoir moves from the initial position 300 m from the toe of the dam to the downstream direction of the dam, and in the 75th year after the reservoir impoundment, that is, 2082, the boundary of the leakage recharge zone tends to be stable) the upstream water level of the reservoir is 500 m. The boundary of the leakage recharge area of the reservoir moves from the initial position 300 m from the toe of the dam to the downstream direction of the dam, and the movement of the boundary of the leakage recharge area tends to be stable in 2045, 40 years after the reservoir impoundment. 5) the analysis results before and after the improvement of seepage control measures in Chara Reservoir show that the improvement of seepage prevention measures for dam foundation is effective in preventing and curing soil salinization around the reservoir.
【学位授予单位】：新疆农业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：S156.41;TV223.4

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