3D seepage flow analysis reflecting hydro-geological structure with line cracks in a landslide-Example of analysis in the SHIONOYAMA Landslide area

Stratum water and crack water passing through cracks of bedding planes and joint surfaces significantly influence the amount of displacement of moving mass in a landslide area. Measuring technology using borehole imagers has recently advanced and enabled us to determine crack direction, crack scale, crack frequency and loose zones in the ground. We have developed three-dimensional seepage flow analysis for dealing with aspect cracks and line cracks from joint surface or schistosity planes. In this paper, we accurately modeled structures containing an enormous number of line cracks and conducted three-dimensional seepage flow analysis in the SHIONOYAMA Landslide area. As a result, we found that line cracks tend to decrease the pore water pressure. In addition, the response of water pressure to rainfall was found to be delayed and the profile became sluggish for deep groundwater. We demonstrated that we were able to analyze a three-dimensional seepage flow of ground filled with line cracks.