Mapping of leakage paths in damaged embankment using modified resistivity array method

초록

The cause and path of leakage in a damaged embankment in Korea were interpreted through integrated 3-D resistivity inversion. Data from a modified electrical resistivity survey were analyzed for cross potential array, direct potential array, and D-Lux array. These proposed modified arrays used line source, point source, and borehole source for data acquisition in the embankment. The modified electrical resistivity survey is a method to predict the path of a leakage by connecting the regions where the current flow gathers, and the potential difference is reduced when the current flows through the embankment. Therefore, this method takes the potential differences as data and calculates the potential distribution for the target area to interpret the path of the current flow. Analysis of the modified survey data revealed the existence of two zones suspected of leakage in the downstream slope. One region was identified as an end drainage pipe, and the other was the right abutment, where the leakage occurred. The 3-D inversion model was built through modified electrical resistivity tomography. In the 3-D model, the resistivity anomaly at the right abutment matched a low-resistivity zone in the modified survey data, and it means that the results of traditional 3-D survey support those of the modified electrical resistivity survey. For reliability of interpretation, we verified the findings based on the evidence of actual leakage on the embankment surface. Through comparative analysis, the cause and route of leakage of the fill dam could be predicted and verified.

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