Evaluation of Slope Stability Analysis (Case Study of Arba Minch-Belta Road)

Abstract

The analysis of failing slopes requires an in-depth understanding of the failure mechanism in order to choose the right slope stability analysis method. The effectiveness of any slope failure remediation method depends on the analysis method. This thesis focuses on cut slope stability analysis with the Finite Element Method computer program Plaxis 2D for both drained and un drained cases for the case of Arba Minch-Belta Road and a comparison of the analyzed result. The finite element method needs additional information regarding the potential perfo rmance of a slope. The purpose of this study is to evaluate the causes of soil slides that contribute to slope instability and to recommend suitable remedial measures via assessment of the landslide that occurred during the construction of Arba Minch-Belta Road at station 17+990 to 18+170. For this purpose, the geotechnical parameters of the mobilized soil along the slide surface were determined by laboratory testing and correlations of the parametersof the soil at three profiles. The slope was then modeled using FE software PLAXIS applying Mohr-Coulomb constitutive model along the most representative profiles of the study area by considering the landslide mechanism and the parameters determined from soil testing. The analysis was done for drained and undrained scenarios and the factor of safety calculated for both cases using phi-c reduction by utilizing incremental multipliers. The most suitable slope remediation technique was determined to be densification by use of explosives which helps in increasing the shear strength of cohessionless soils and stability of slope, sheet piles and retaining walls installed to provide lateral support and to increase the stability even if the method is quite expensive and providing drainage helps in reducing the seepage forces and hence increase the stability.