Verification of the Probability Prediction Method of Hazard Area for Rock Mass Failure

Rock mass failure can cause considerable damage, such as that suffered during the 1996 Toyohama Tunnel Collapse in northern Japan. Therefore, a hazard map using GIS for rock mass failure is studied as one of the disaster prevention and the management techniques. For making the hazard map using GIS, authors have already proposed a probability prediction method of the hazard area using multivariate statistical analysis. In this study, we verified the prediction method as applied to actual failure examples, and evaluated the debris scattering pattern based on literature data. Understanding of the debris scattering pattern is important in order to make the hazard map. As a result, it became clear that this prediction method could be applied actual failure samples if the failure type is a rock mass failure. When we regarded the debris scattering pattern on the prediction as a rectangle that makes total horizontal reach and spread width, it was admitted that actual debris fell within the range of 40-60% of the rectangle i. e., the accumulation distribution probability. However, the actual debris scattering pattern may spread depending on slope conditions farther than the prediction value. Considering these results, we will aim at construction of a hazard map system using GIS for rock mass failure.