Abstract
The subject of present research is concerned with in-service slopes that collapse due to heavy rain. The authors proposed a procedure to formulate slope collapse or noncollapse judgement system together with the new slope collapse factors, time and rain-fall, in addition to the previously proposed ones. The data used in the analysis are collected from several cut-off slopes constructed on three types of sites (metamorphic, sedimentary and igneous). From these data, the factors that bear an impact on the collapse of slope during heavy rain are clarified and some problematic points are brought under scrutiny in forecasting the slope collapse.
