3:45 PM - 4:00 PM
[HTT26-08] Geoelectrical monitoring of changes in water content in an embankment using a large-scale rainfall simulator
Keywords:Geoelectrical monitoring, resistivity, water content, large-scale rainfall simulator, slope disaster
In order to confirm the changes in resistivity and water content by rainfall in detail, we conducted the artificial rain experiments, controlling the total amount and intensity of rainfall using the mobile simulator. Eleven experiments were conducted in 2012, 2013, 2014. It was difficult to obtain the rapid change of resistivity structure due to the heavy artificial rain with ordinary geoelectrical equipment, because the analysis of resistivity structure requires measurement by much electrode array combination. In these experiments, therefore, we performed only a continuous measurement using a Wenner array with “a” spacing of 0.5 m and 1 m. The apparent resistivities changed significantly with a rapid change in water content, indicating that geoelectrical monitoring is effective in assessing the condition of a slope during rainfall.
In three experiments in 2015, we used a high-speed resistivity profiling system which can provide 576 (24x24) data in about 10 seconds for the resistivity monitoring. The pole-pole resistivity data were collected at intervals of 1 or 2 minutes and a series of resistivity sections were obtained along the slope of the embankment. The result shows that the high-speed geoelectrical monitoring is effective for observing soil moisture changes caused by heavy rain in real time.