[HDS11-P02] Self-potential approach to understand groundwater condition for rainfall-induced landslide forecast : A flume experiment with 2 layered soil
Keywords:landslide, self potential method
In the initial 30 min, water flow under the slope is vertical. After 30 min elapsed, the partial saturation began near the boundary of the two layers in the middle part of slope, where the gradient slope changes; the upper part is steep and the lower, calm. It is considered due to difference of soil consolidation. After 40 min from the start, the saturated area expands and lateral flow increases gradually. For electric properties, in general the area of the lower potential expands with increase of the saturated area. After 30 min passed from the beginning, intense electric field is generated at the boundary of 2 soil layer at the middle part of the upper slope. It seems to correlate with the pore pressure changes or partial saturation. This electric field looks like maintain until the main collapse. In addition, near the slip surface, there is also intense electric field, this is the similar tendency what we had got for the single layer experiment. Further consideration will be required but this is highly suggestive of the more complexity of the groundwater flow under the slope in the 2 layered test. Details will be shown in our presentation.