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以延边地区珲乌高速公路八家子路段草炭土沼泽湿地作为目标研究区,通过现场勘探试验,探明了该路段的地层分布情况,通过现场抽水试验和示踪试验,确定了相关的水文地质参数。并在此基础上,根据研究区水文地质特征,利用Visual Modflow将模拟区垂向概化为3层;根据抽水试验计算结果,并通过模型识别调参,最后确定模型区的平均导水系数为141 m2/d,平均释水系数为2.61×10-4,给水度为0.3,孔隙度为0.6。建立了基于数值模拟的地下水水流模型和地下水溶质迁移模型,分析了公路建设对湿地水系连通性所产生的阻隔效应;并对有无公路情况下地下水水位、地下水流场变化及公路覆盖区地下水流量的变化进行对比。研究结果表明,在有公路情况下,导致公路北侧水头普遍高于南侧,路基两侧地下水水位差较无公路时增加了0.5 m左右,可见公路建设对地下水流产生了一定的影响;另外,公路覆盖区流量较无公路时减小了60%左右,尤其是公路覆盖区南侧的流量较无公路时减少了70%左右。同时,以氮元素为对象进行地下水溶质迁移模拟,预测公路建设对湿地溶质迁移所产生的影响,研究结果表明,在有公路情况下,公路两侧的浓度分布出现了浓度差,公路上游部分区域溶质浓度较无公路情况下较大,可见公路建设对湿地区溶质迁移产生了明显的阻隔效应。
Based on the peat wetland in the Bajiazizi section of Yanwu Expressway in Yanbian area, the stratigraphic distribution of this section was ascertained through on-site exploration and test. Through on-site pumping test and tracer test, the related hydrogeology parameter. Based on the hydrogeological characteristics of the study area, Visual Modflow is used to vertically generalize the simulation area into three layers. Based on the results of pumping tests and the adjustment of the parameters, the average hydraulic conductivity of the model area is determined as 141 m2 / d, the average water release coefficient of 2.61 × 10-4, water supply was 0.3, the porosity of 0.6. The groundwater flow model based on numerical simulation and groundwater solute transport model are established, and the barrier effect of highway construction on wetland water system connectivity is analyzed. The groundwater level and groundwater flow field change and groundwater flow in highway coverage area with or without highway are analyzed The changes are compared. The results show that in the case of highway, the head of water on the north side of the highway is generally higher than the south side, and the difference of groundwater level on both sides of the roadbed is about 0.5 m higher than that of the highway. This shows that the highway construction has a certain impact on the groundwater flow; , The traffic in the road coverage area is reduced by about 60% compared with that without the highway, especially the traffic on the south side of the road coverage area is reduced by about 70% compared with that without the highway. At the same time, the simulation of groundwater solute transport is carried out using nitrogen as object to predict the impact of road construction on the solute transport in wetland. The results show that concentration concentration difference appears on both sides of the highway in the case of highway, The solute concentration is larger than that in the absence of highways, which shows that highway construction has obvious barrier effect on solute transport in wet areas.