Analysis of Slope Stability of Fly Ash Stabilized Soil Slope

Abstract

Fly ash is a waste product of thermal power plants, can be used as embankment material, stabilization of soft soils, road sub-base constructions, and other geotechnical fields. In this study, fly ash is used as soil stabilizer for an embankment slope. This paper discusses the shear strength parameters of the soil stabilized with fly ash. The soil has been mixed with 10, 20, 30, and 40% fly ash by dry weight for conducting modified Proctor compaction test and direct shear test. The experimental results indicate that the dry density and cohesion value of soil decreases where as the angle of internal friction increases with increase in the percentage of fly ash. The analysis of slope stability of native soil and stabilized soil has been studied by Fast Lagrangian Analysis of Continua (FLAC) slope software. Parametric study has been done to calculate the factor of safety by considering different slope height at constant slope angle under summer and rainy season. The analysis revealed that the slope with native soil was stable up to 12.0 m height under both summer and rainy season. With further increase in height, the slope becomes critically stable and failed under rainy season at 14.0 m height. The addition of fly ash enhances the strength and provides resistance to slope instability under both the conditions up to 14.0 m height. It has been found from the analysis that the factor of safety increases with increase in percentage of fly ash at a particular height. 30% fly ash is obtained as optimum amount as stabilizer for a slope of certain height.