高密度电法在堤防渗漏抢险探测中的应用

汛期高水位下土质堤防承受高渗透压力易产生渗漏、管涌乃至决口等险情,为了在险情出现前对堤防的状态进行了解,对处于汛期持续高水位或发生险情前期的土质堤防进行快速隐患探查并进行渗漏风险评估,对一种基于高密度电法的探测模式进行了可行性研究,分析了高密度电法用于堤防抢险探测的物理优势。通过石臼湖堤防抢险探测试验表明:当土质堤防持续在高水位下挡水,堤身隐患(如孔洞、松散体、裂缝等)处的土体含水率将升高,电阻率将和周围土体产生差异,表现为低阻异常闭合圈;高密度电法对于土质堤防的低阻异常区具有较好的识别效果;通过分析堤防视电阻率值的大小和相对关系,以及视电阻率等值线的形态,对堤防进行渗漏风险评估,圈定了堤防的渗漏高风险发生区域,成功预测到了12 h后石臼湖堤防多处渗漏和管涌点的发生区位,证明高密度电法用于堤防渗漏抢险探测和风险评估是行之有效的。

Application of high density resistivity method to detection for risk-elimination of embankment seepage

The high seepage pressure on embankments during the flood season may cause leakage，piping and even structural failure. In order to know the state of embankment which can prepare for emergency，this study have a research on a detection mode based on the high density resistivity method. In order to carry out quick detection of hidden danger for the earthfill embankment under continuous high water level or before the occurrence of risk during flood season，a feasibility study is made on a high density resistivity method-based detecting mode，in which the physical advantage of the application of the high density resistivity method to the detection of risk-elimination for embankment is analyzed. Through the detection of risk-elimination made for the embankment of Shijiuhu Lake，it shows that the soil moisture content of the hidden danger ( such as holes，loose bodies，cracks，etc. ) will rise，and the resistivity will be different from the surrounding soil，and the surface is the close ring of low resistance when the soil embankment keeps retaining water at high water level. The high density resistivity method has a better identification effect for the low resistance abnormity area of earthfill embankment. Through analyzing the magnitude of apparent resistivity value and the relative relation of embankment as well as the contours of apparent resistivity pattern，an assessment on seepage risk of embankment is made，and then the possible seepage risk occurrence areas of embankment are defined，thus several occurrence locations of seepage and piping points are successfully detected，which demonstrates that it is feasible and effective to detect seepage risk of embankment and assess the relevant risk with the high density resistivity method.