Three-dimensional limit equilibrium slope stability analysis on real slope failures caused by heavy rain and earthquake

This study presents three-dimensional slope stability analyses that reproduce actual slope failures induced by a heavy rain and an earthquake. Hovland method, which is one of the three-dimensional limit equilibrium methods, is employed to evaluate the stability of slopes over wide area. While forces acting on soil column are ignored in the method, its low calculation cost enable us to utilize the method in wide-area slope stability analysis. In order to confirm the accuracy of the method, slope failures actually caused by the heavy rain and earthquake are reproduced. The obtained results are compared with distribution maps of the real slope failures with the help of the concept of a ROC curve. According to the results of the slope stability analyses, it was confirmed that the Hovland method outputs relatively lower values of safety factor than actual slope failures. In addition, the effect of multi-hazard condition of earthquake and heavy rain is numerically examined.