Assessment of slope stability at landslide area in B’LaoWard, Bao Loc city, Lam Dong province and solutions to prevent landslide

Abstract

Bao Loc is one of two cities of Lam Dong province. Located on Di Linh – Bao Loc plateau about 800 – 1000m elevation, Bao Lọc has the complex mountainous terrain. The authors have surveyed and collected information and samples in the landslide area. This area occurred the cracks, damaged several buildings within 1.2 ha. The authors have also identified causes of landslide such as geomorphotogy, stratigraphic slope, slope materials, hydrogeology, climate, etc. However, the main cause was soil extraction activities at toe of slope which lost the counterweight berm, associated with the moisture increase of soil due to heavy rainfall in rainy season. It reduced the shear strength of slope materials. Based on data analysis of surveyed location, the authors applied GeoStudio software by SLOPE/W module so as to calculate the slope stability under the sections. Analyzed results showed that the slope was stable in dry season with the minimum factor of safety (FS) around 1.474, in rainy season the slope was unstable with minimum the factor of safety around 0.896 commensurate with groundwater present model. The minimum factors of safety in the model with the appearance of groundwater table are represented by the distance among the slope sections following the relationship function with correlation coefficient (R2) is 0.9915. According to the interpolated result from the relationship function showed that the width of unstable area or the width of sliding mass is 35.1m. As the obtained results, the authors proposed realizable solutions to stabilize the slope in order to minimize the effect of landslide at the study area.