Slope Safety Factor and Its Relationship with Angle of Slope Gradient to Support Landslide Mitigation at Jatinangor Education Area, Sumedang, West Java, Indonesia

Abstract

In several studies on slope stability analysis, the FS (Factor of Safety) value plays an important role in determining the meaning of slope stability. Based on several landslide events, Table of Bowles (1989) gives FS < 1.07 for the usual occurrence of slope collapse, 1.07 <1.25 for slope collapse ever occurred, and FS> 1.25 for collapse events are rare. FS is influenced by the angle of the slope (\alpha, degree), then Table of Bowles (1989) can be modified based on analysis of relationship between FS value with slope angle. The result of stability analysis of soil slope in Jatinangor Education Area is found the equation α = 7.2300.FS-0.474, at outside of drainange area, but in drainage area shows a variety of different safety factors. So that the meaning of labile, critical, and stable in slope stability analysis at out of drainage area gives α > 56° for the usual occurrence of slope collapse (or labile slope); 56° > α > 41° for slope collapse ever occurred (or critical slope), and α < 41° for collapse events are rare (or relative stable slope). Furthermore, this modification can be used for landslide mitigation.