Reliability of Probabilistic Finite Element Method Over Deterministic and Traditional Probabilistic Method in Slope Stability Analysis
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Date
2022-04
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Addis Ababa University
Abstract
Slope Stability is one of the crucial topics in geotechnical engineering to be investigated
well because oftentimes slope exists naturally or formed artificially during construction of
various civil engineering structures which needs to be at equilibrium. For that matter, there
are various methods of analysis. For the last couple of decades, it is observed hard for
Engineers to use Probabilistic Slope Stability Analysis due to many reasons. But these
days, technological advancements which led to having more rigorous software packages
made it be possible to use in the analysis and its merit. The aim of this thesis is to show
the use of more reliable method of slope stability analysis for hypothetical back slopes in
Addis Ababa where red clay soil is dominant and that is achieved by comparing methods
based on a factor of safety, probability of failure, and reliability index.
Limit Equilibrium Method (LEM) and Numerical Method are used for this purpose. Both
deterministic and probabilistic analyses are carried on by modeling seven slope geometries
with different input parameters from Addis Ababa ring road III project and hypothetical
slopes using a two-dimensional Slope Stability analysis software called SlideV6.0. A
Global Minimum type of analysis are carried on by using the Slide software. For finite
element analysis and probabilistic finite element analysis, RS2 software from Rocscience
is used. Uncertainty is accounted for in a better way in probabilistic analysis by defining
parameters as a random variable in link with other features.
It is shown by this study that, Probabilistic Finite Element Analysis (PFEA) seeks out the
most critical slip surface than that of the finite element method. In addition, even if the
factor of safety found from the deterministic analysis is greater than one still a probability
of failure is observed. Moreover, it is attested that the factor of safety is not the only
measure for slope stability, but other measures exist while using probabilistic analysis.
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Keywords
Slope, Probabilistic analysis, FEM, PFEA, Slope Stability