Application of the method of estimating slip plane through ground surface displacement of landslide; case studies in Japan and Romania

When a landslide has occurred, it is important to carry out emergency measures immediately after clarifying scale and characteristics of the landslide. We consider that it is important to estimate the slip plane shape immediately and accurately. Therefore, we have developed the method of estimating slip plane through ground surface displacement of landslide. The purposes of this study are checking this method using actual measurement data of ground surface displacement, and examining what is necessary to estimate slip plane appropriately. In this presentation, we will show three landslides case-studies: two in Japan and another landslide in Romania. The landslide 1 occurred at a cut slope under cutting works, and surface displacement vector data were acquired by total station. The landslide 2 occurred at a natural slope, and surface displacement vector data were acquired by aerial photogrammetry. And the landslide 3 occurred at a road side slope, and surface displacement vector data were acquired by total station. Results suggest that surface displacement vector data should be acquired at the initial stage of the landslides. In addition, it should be better to set ground surface measurement points at head, central part and toe of the landslides, and more than three measurement points should be settled. Further, it should be better to revise the ratio of slope length to displacement vector length as 1:0.005. We also consider that this method can estimate the slip plane shape accurately, reflecting some data which are obtained from field survey like head scarp gradient, and using the ground boundary parameter. At the present moment, this method depends on personal judgement about the position of the ground boundary parameter or others for adequately estimating the slip surface shape. Thus, to improve this method, we need more case-studies to be considered in our study. Image of this method