Probabilistic methods of slope stability analysis. The Case of Wozeka-Gidole Cut Slope

Master's Thesis from the year 2013 in the subject Engineering - Civil Engineering, grade: 3.74, Arba Minch University, language: English, abstract: Probabilistic methods of slope stability analysis accompanying conventional analyses provide the means for the reliability and probability of failure of the slope in a quantifying way. They provide us an important knowledge for stability condition of the slope. The essential requirement of the soil parameters is determined in the laboratory for the analysis of the slope meeting the insitu conditions. For the location of the phreatic surface three different scenarios were considered for the profile of the water surface to carry out the analysis. Effective strength parameters were considered to assess the long-term stability condition.

The spatial variability of the random variables was incorporated into this model and by considering the contributions of the end resistance of 3-D probability of failure. The 3-D aspects of failure were investigated using FLAC3D software incorporating all the parameters of the soil to visualize the failure probability for the scenarios. Both normal and lognormal distribution of FOS were considered in order to compare and contrast the reliability and probabilities of failure in a measurable ways using NORMDIST and NORMSDIST program which is integrated in MS-EXCEL and from the probability density function table. The analysis gave that Probability of failure for normal distribution is higher than that of probability of failure for lognormal distribution. It was also attempted to investigate the best combination of the slope parameters to have the desirable target probability of failure for the scenarios and recommendation were made to provide geosynthetic reinforcement for stabilization and construct appropriate retaining wall with proper drainage as well as provision of sheet pile to achieve the desirable postulated probabilities of failure.