二元结构库岸动态浸没过程数值评价与对比

江西省新干航电枢纽工程库区左岸系赣江河流阶地,具有典型的二元结构特征。刻画水库蓄水后二元结构库岸地下水的动态浸没过程是合理地进行库区浸没评价的前提。分别建立双侧河渠潜水和承压含水层地下水非稳定流运动解析解和区域地下水三维非稳定流数值模拟模型,对比评价水库蓄水后二元结构库岸的地下水动态变化过程。结果表明:在评价前期,解析法和数值法均能够刻画库区蓄水后库岸地下水浸没的动态变化规律和趋势;然而在评价中后期,降雨入渗因素对地下水浸没的作用逐渐凸显,数值法的计算结果更为合理。同时,基于数值法,结合浸没评判标准,预测蓄水至第3年末的浸没面积将增大至10.91 km²。研究成果可为工程前期浸没控制方案的布置提供科学依据。

Application and Comparison of Numerical Methods for AssessingDynamic Immersion of Dual-structural Reservoir Bank

Situated at Ganjiang River Terrace, the left reservoir bank of Xingan Navigation and Power Junction Project is a typical double-layer hydrogeological structure. Depicting the dynamic process of groundwater immersion in the double-layer structural reservoir bank after impoundment is a prerequisite for assessing reservoir immersion reasonably. In this study we established analytical solutions for the transient groundwater flow in upper unconfined and lower confined aquifers between two lateral watercourses and a three-dimensional numerical model of transient groundwater flow for comparative study. Furthermore, we evaluated the influencing range of groundwater immersion based on the judging criteria of reservoir immersion in Ganjiang section. The comparison results indicate that in early stage of assessment both the analytical and numerical methods could describe the dynamic process of groundwater immersion after impoundment. However, in the middle and late stages of evaluation, the result of numerical method is more reasonable as the effect of rainfall infiltration on groundwater immersion gradually becomes more prominent. Meanwhile, the immersion range will increase to 10.91 km² at the end of the third year predicted by the numerical modeling. The research findings provide scientific basis for the design of immersion controlling.