高密度电法在水电站选址覆盖层厚度探测中的应用

AN APPLICATION OF HIGH DENSITY RESISTIVITY METHOD IN THE INVESTIGATION OF OVERBURDEN THICKNESS FOR THE LOCATION OF HYDROPOWER STATIONS

高密度电阻率法是以人工向地下施加外电场,然后通过探测场的参数变化获得电性局部差异,从而认识被测目标的一种勘探手段。该方法可利用覆盖层与下部基岩存在的电性差异来测定覆盖层的厚度。由于其效率高、探测深和精确的地电剖面成像,已成为在水文和工程地质勘察中最有效的方法之一。这里简要阐述了高密度电阻率法发展过程、勘探原理、野外工作方法,并将该方法应用到水电站选址覆盖层厚度探测中,获得了测区部位的视电阻率二维成像图。结合测区地形地质条件、地球物理特征,通过对视电阻率二维成像图异常形态,高低阻等特征的分析,推断出了地下覆盖层厚度,为水电站选址建设提供了依据。

High density resistivity method is a kind of exploration technology, which surveys underground geology targets by measuring electrical difference in an establishing active electric filed in earth. The method can determine the overburden thickness based upon the electricity difference between overburden and lower datum rock, and is one of the most valid method with high-efficiency, depth and accuracy for ground electricity section imaging in hydrogeology and engineering geology. This article mainly introduces its development process, exploration theory and field work method. A real case application to the overburden thickness investigation is presented to show that the underground overburden thickness can be inferred by analyzing the abnormity shape, high and low resistance of the surveying 2D resistivity imaging profile combining with the terrain, geological conditions and geophysical characteristics of the measured region, which is the basic data for the location determination of a hydropower Station.