Estimation of Critical Sloping Ratio of Soil Slope Pretected by Isopachous Riprap Wang KehongThis paper is based on the fundmental hypothesis about stability analysis of soilslope proposed by Fellenius. It is assumed that the sliding surface of soil a circular surface, andalso the model is reduced as a plane problem. Here, paper develops the concept of critical slopeof soil slope, considers primary factors and conditions of soil sliope, by use of static equiblibriummethod, a simple and easy formulas available for estimating soil slope to be reliable or not is de-rived.Critical sloping;;Isopachous riprap;;Fellenius