Spatial variability of material properties for slope stability analysis and fragility curve generation

This dissertation studies the effects that the spatial variability of soil properties has upon the behavior of slopes subjected to dynamic loads. By their very nature, soil properties are not homogeneous. However, slope stability analysis (SSA) in engineering practice rarely considers these variations and assumes homogeneous soil properties throughout the entire slope. It is the goal of this study to determine the effect that random soil properties will have upon the damage suffered by a slope.; Because in-situ soil testing as it is currently carried out cannot be performed at the resolution of the variations in soil properties, statistical methods must be employed to fully realize these fluctuations. These properties are synthesized using the spectral representation to simulate n-dimensional non-Gaussian stochastic fields based upon a probabilistic analysis of a series of piezocone tests. Monte Carlo simulations are conducted by performing non-linear finite element analyses upon slopes subjected to earthquakes that vary in both intensity and frequency content. Furthermore, simulations are performed with deterministic material properties that have the same mean values as the corresponding random properties for comparison purposes. It is concluded that using deterministic material properties to perform SSA provides results that are unconservative.; A further objective of this study is to consider the effectiveness of the finite element method for performing static SSA. The finite element method used to perform SSA has begun to be accepted as a means of analyzing slopes as computer advances have reduced the amount of computation time necessary. Traditional limit equilibrium methods will be compared to determine the accuracy of the finite element method.; The final goal of this dissertation is to calculate fragility curves for slope stability. Fragility curves graphically depict the probability that a slope will exceed a certain amount of damage given a specified intensity of earthquake. Curves will be generated for earthquakes with different frequency content, in order to determine its effect upon slope stability. Different intensity measures will be employed to determine how effective they are for a fragility curve analysis. Once again, the effect of the spatial variability of soil properties will be considered and discussed.