To provide a method and a device for accurately positioning an impervious sheet-restoring shaft bored in a waste disposal plant.
Metallic bars F are vertically driven up to a prescribed depth 43 from the surface of waste 6 in plural positions in a division H including a water leakage position 11 on an impervious sheet 10 arranged on the bottom surface of the waste disposal plant 2, and a water leakage signal according to a distance to the lower end of the metallic bars F from the water leakage position 11 is detected. Horizontal coordinates of the water leakage position 11 are estimated on the basis of the water leakage signals detected in the plural positions, and the shaft 7 for restoring the impervious sheet 10 is positioned on the estimated horizontal coordinates. Desirably, when electrodes Bi and Cj are arranged on the gropund side of the impervious sheet 10, the metallic bars F are driven at an interval narrower than a required diameter of the restoring shaft 7 in the division H, the upper end of the metallic bars F and the electrodes Bi and Cj are connected to a power source 16, electric currents IBi and ICj flowing to the electrodes Bi and Cj are detected as the water leakage signal, and the horizontal coordinates of the water leakage position 11 are estimated on the basis of the electric currents IBi and ICj detected in the plural positions.
TSUCHIHIRO MICHIO
HAYAZAKI TSUTOMU
IWAMOTO AKITOSHI
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