SLIP SURFACE IN A CLAY-SAND MIXTURE SLOPE TEST USING SCALED LABORATORY MODELS

Determining the assumed failure slip surface is the most important phase in slope stability analysis. Determining the slip surface is still a basic problem in practical engineering. The right assumed slip surface has never been entirely resolved. The focus of this study is the determination of the slip surface on a slope made from a mixture of clay and sand. The slope materials were created in 2 combinations, namely Combination-1 consisting of 30% clay + 70% sand, and Combination-2 consisting of a mixture of 50% clay + 50% sand. The experimental works were carried out using a glass box measuring 110 cm x 40 cm x 10 cm with a thickness of 10 mm, a pressing device, a proving ring, dial gauges and colored marks. The applied load on the model was uniformly distributed. The Fellenius method was adopted to compare to the experiment results. The Fellenius method was carried out using trial and error at 60 coordinate points. The analysis results using the Fellenius method indicated a single critical slip surface at a single coordinate point. The results of the slip surface using the experimental work showed that there was a combination of a linear and rotational slip surfaces. This is in contrast to the Fellenius slip surface, which was rotational.