ANALISA PENYEBAB TERJADI LONGSORAN DITINJAU DARI STABILITAS TANAH DAN PENGURANGAN RESIKONYA

Abstract

Slope stability in some areas has an important role in reducing the risk of landslides. Heavy rains that occur during
the rainy season may cause the land to become landslides and allow disasters to occur. To reduce any risks, it is
necessary to analyze the stability of the slopes before and after the slope reinforcement by using gravity type of
retaining wall reinforcement. In the process of slope stability analysis, the authors used a computer-aid program,
namely GeoStudio 2012, which is used to calculate safety figures in a relatively short time. This analysis also used
the simplified Bishop slice method to determine the slope stability. Soil samples to be tested in the soil mechanics
laboratory are taken directly from the landslide location and are surface soil samples. Samples were taken in the
form of undisturbed samples and disturbed samples. Based on the slope stability analysis before the reinforcement,
the upper slope’s safety factor is 0.944 by manual calculation and 0.990 by using the Geostudio 2012 program,
meanwhile, the lower slope’s safety factor is 1.039 using manual calculations and 1.045 using the GeoStudio 2012
program. Reinforcement of slope stability using gravity type retaining walls with control of overturning, shearing,
and soil bearing capacity. After strengthening the slopes using gravity-type retaining walls, then the slope stability
analysis was carried out using the GeoStudio 2012 program. The result obtained is that safety factor for the upper
slope is 2.484 and for the lower slope is 2.131, which means the slope stabilities are safe or stable.
Keywords: slope stability, safety factor, gravity wall, and landslide.