Abstract
In order to carry out the preventive maintenance control of expressway slopes, it is important to accurately understand the ground condition of slopes, followed by estimating the damaged area. Such ground condition is presently investigated by boring and/or physical prospecting on the slope surface. For the slopes widely distributed along expressways, however, a change of direction from the present corrective maintenance control to the preventive one is required. Therefore, it is indispensable that the critical slopes can be detected efficiently and economically. In this paper, an experimental investigation was carried out, applying the helicopter electromagnetic (HEM) method, by which the ground resistivity distribution of wide area can be detected, to some available expressway slopes. Based on the investigated data, the influence of the different prospecting techniques of HEM and the metal obstacles of slope reinforcements on the resistivity, and the estimation reliability of ground condition due to the resistivity were examined. As the results, it was confirmed that the ground condition of slopes can be understand effectively by the HEM prospecting data, especially detecting the areas of high volume water content. Finally, the applicability of HEM to the preventive maintenance control on expressway slopes was elucidated.
