基于高密度电法的淤地坝渗透特征研究——以延安市治沟造地工程为例

    STUDY AND APPLICATION OF HIGH-DENSITY ELECTRICAL INVERSION OF INFILTRATION CHARACTERISTICS OF SILT DAMS—TAKING THE CASE OF YAN'AN GULLY LAND CONSOLIDATION PROJECT AS AN EXAMPLE

    • 摘要: 淤地坝是黄土高原地区重要的水土保持工程,在延安市治沟造地地区中为水土流失、防洪减灾、储存水源等方面发挥着十分重要的作用,然而近年来淤地坝出现了许多由渗透现象引起的工程地质问题,当地居民的生命财产安全造成了威胁。本篇文章使用物探方法对延安市内6座淤地坝进行渗透特征研究,通过在研究区内展开高密度电阻率反演实验,获得了6个淤地坝的视电阻成像色谱图,并总结分析得到了6座淤地坝的渗透路径以及渗透特征,结果显示该地区淤地坝渗透方式主要存在两种,即绕坝渗透与坝体渗透,这两种渗透方式在研究区内造成了不同影响的不良工程地质现象。通过野外调查并结合研究区内DEM数据我们总结出影响淤地坝渗透特征的3个显著的影响因子(地形、水位、坝体性质)。同时我们根据获取的试验数据进行水文计算,结果显示研究区内淤地坝上下游水力梯度与发生不良工程地质现象的概率呈正相关,即当上下游水力梯度大于0.15时淤地坝地区会出现由地下水渗透引起的工程地质现象,同时本文针对特定的问题,提供了特定的防治建议以及措施。

       

      Abstract: Silt dams are important soil and water conservation structures in the Loess Plateau, playing a crucial role in controlling soil erosion, mitigating floods, reducing disasters, storing water, and improving land in the Yan'an region. However, in recent years, seepage-related engineering geological problems have emerged in these dams, posing risks to local lives and property. This study applied geophysical exploration methods to investigate the seepage characteristics of six silt dams in Yan'an. High-density electrical resistivity surveys were conducted, and the resulting inversion data provided visualized resistivity imaging profiles for the six dams. The seepage pathways and features of the dams were summarized and analyzed. The results indicate that seepage in the area occurs mainly in two modes: bypass seepage and through-dam seepage. Both modes have induced adverse engineering geological phenomena of varying severity. Based on field surveys and digital elevation model(DEM)data, three key factors influencing seepage characteristics were identified: topography, water level, and dam properties. Hydrological calculations performed using the experimental data show a positive correlation between the Hydraulic Gradient across the dams and the probability of adverse engineering geological events. Specifically, when the Hydraulic Gradient exceeds 0.15,groundwater seepage is likely to cause engineering geological problems in the silt dam area. Furthermore, specific prevention and control recommendations and measures are proposed to address the identified issues.

       

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