黄土丘陵沟壑区挖填工程影响下地下水流数值模拟

Numerical Simulation on the Influence of Groundwater Flow Caused by Excavation and Filling in Loess and Hilly-gully Region

为了确定挖填工程活动对地下水流场的影响程度及控制范围,本文在详细分析某黄土丘陵沟壑区地质与水文地质条件的基础上,基于三维有限元软件Feflow和GIS技术建立了研究区水文地质概念模型、数学模型及采用等效方法建立的地下水流场数值模型。数值模型设置3种工况:地表不硬化沟底不设盲沟(工况A)、地表硬化沟底不设盲沟(工况B)和地表硬化沟底设盲沟(工况C)。研究结果表明:从时间上,40年后工况B、工况C地下水位趋于稳定,工况A地下水位仍然不稳定,且水位有上升趋势;从空间上,40年后,3种工况地下水位等值线方向均发生偏转,与改造后地表标高近于平行。但工况A水位等值线密度最大,工况B次之,工况C密度最小,在研究区相同地点,工况A地下水位最高,工况C最小。工况C对地下水位的控制作用最为明显,对黄土丘陵沟壑区中的挖填工程最为有利。

In order to determine the degree and the range of influence of the groundwater flow field by the excavation and filling engineering in the loess and hilly-gully area, based on the geology and hydrogeological conditions of the research area, the hydrogeological conceptual model, the mathematical model and the numerical model were established by equivalent method with Feflow and GIS technology. Numerical model included three engineering situations： Case A was unhardening and no blind ditch, Case B was hardening and no blind ditch, Case C was hardening and blind ditch. The study show that： with respect to time, the groundwater levels of Case B and Case C are stable forty years later, while Case A remains unstable and rising; with respect to space, the groundwater level isolines of all cases deflect, nearly to parallel to the transformed surface （Case A is the most intensive, Case B follows, and Case C is the least intensive）, and on the same position in the study area, the groundwater level of Case A is the highest and C is the lowest. According to the analysis results, Case C shows obvious controlling effect on groundwater level, which is the most advantageous to the excavation and filling in loess and hilly-gully region.