PROPOSAL FOR ESTIMATION METHOD OF A SATURATED ZONE FORMATION TIME IN SLOPE FAILURE HAZARD PREDICTION BY MODIFIED I-D METHOD

A modified I-D method was proposed for the purpose of improving an accuracy of slope failure risk prediction. This method was added the results of on-site measurement by a tensiometer to the concept of rainfall index. Since the formation of a saturated zone in a slope could lead to slope instability, it is important to estimate the time (tsat) of formation of saturated zones. In this study, a new estimation index for tsat using rainfall index was proposed. As a result, the relationship between the average rainfall intensity and the duration between the beginning of rainfall and the formation of the saturation zone was shown the best result. Furthermore, by incorporating this result into a modified I-D method, the number of correct estimations increased significantly compared to the existing rainfall index. Therefore, by the proposed rainfall index of tsat, it was confirmed that the slope collapse can be predicted only by the rainfall data, and the accuracy was improved.