SLOPE STABILITY ANALYSIS OF VOLCANIC RESIDUAL SOIL USING LIMIT EQUILIBRIUM METHOD: CASE STUDY AT CIBITUNG AREA, PANGALENGAN, WEST JAVA

• Main Author: Winarto, Irwan
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/47272
• Institution: Institut Teknologi Bandung

An understanding of geological, hydrological, and soil characteristics problems is important in applying the principles of slope stability. Landslide at Cibitung, Pangalengan in 2015 that has occurred in sunny condition after the rain a few days before the landslide, had caused significant damage to roads and geothermal pipelines. Surface cracks were also found around the landslide area. This is interesting to be learned because it is suspected that there is a combination of factors that influence landslides in the study area. Further research is needed to evaluate the causes of slope stability in this area. The common method used for analyzing slope stability is the Limit Equilibrium Method. The analysis is carried out using the stress forces in the calculation. The basis of this analysis is the determination of the applied stress and mobilized strength on a surface failure simulation of a slope. In this research the Limit Equilibrium Method was combined with analysis of the rainfall conditions that occurred before the slope mass collapsed, and the influence of seismic activity. The research area is located in a mountainous morphology with slope of up to 125%. The slope at Cibitung is composed of andesite, andesitic breccia, tuff breccia, and weathered tuff. The last one was transformed tinto residual soil. Cumulative rainfall analysis shows that the critical intensity value is 316.5 mm over a period of 18 days. Factors that cause a decreasing in the level of stability have a different contributed significance. The increasing groundwater level 45%, combining of increased groundwater level with tension crack which value is 47% and seismic factor influence 47%. This condition indicates that an increase in groundwater with tension crack gave the greatest influence on the slope failure at Cibitung area.