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SAMU_3D, a three-dimensional slope stability software, was recently developed by Sultan et al. (2007) to account for complex geometry. The model estimates the factor of safety of a kinematically admissible failing mass using a 3-D analysis based on the upper bound theorem of plasticity developed by Chen and others. One of the main interest of this model is to propose complex critical failure surfaces, suitable for complex bathymetry (i.e. canyons) with a shape of failure surfaces defined using 8 parameters (ellipticity, curvature and size).
A probabilistic approach was recently added to the former deterministic model to consider the effect of soil parameters variability and uncertainties (undrained shear strength, unit weight) on the critical factor of safety. Such approach is often used to estimate the reliability of the results. The Monte Carlo simulation was used to represent the variability of the factor of safety given a specific number of trials. The search for the critical failure surface previously based on the deterministic safety factor is now performed in terms of probability of failure (or probability to have a factor of safety lower than an arbitrary constant). The probabilistic model was partially validated using the well known James Bay embankment case (2-D analysis) for which numerous probabilistic evaluations are available. The new model is applied to assess the present-day slope stability of the Nice airport area where a slide occurred on 1979 and for which a large uncertainty exists regarding the soil parameters distribution with depth.
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