Probabilistic Slope Stability Analysis with Stochastic Soil Hydraulic Conductivity
by Shengxiang Gui, (Dept. of Renewable Resour., Univ. of Wyoming, Laramie, WY 820713354), Renduo Zhang, (Dept. of Renewable Resour., Univ. of Wyoming, Laramie, WY), John P. Turner, (Dept. of Civ. and Arch. Engrg., Univ. of Wyoming, Laramie, WY), and Xuzhang Xue, (Dept. of Civ. and Arch. Engrg., Univ. of Wyoming, Laramie, WY)
Journal of Geotechnical and Geoenvironmental Engineering, Vol. 126, No. 1, January 2000, pp. 19, (doi: http://dx.doi.org/10.1061/(ASCE)10900241(2000)126:1(1))
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Document type: 
Journal Paper 
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by Robert D’Andrea (See full record)

Discussion: 
by Zouhair Mrabet (See full record)

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Abstract: 
The effects of stochastic hydraulic conductivity on the slope stability of an embankment dam are investigated using a combination of random field simulation, seepage analysis, and slope stability analysis. The hydraulic conductivity distribution is treated as a spatially stationary random field following a lognormal distribution. The turning band method is used to generate the spatial variability of the saturated hydraulic conductivity K\ds in the domain. Different standard deviations of log hydraulic conductivity σ_{lnKs}are investigated. For each value of σ_{lnKs} various realizations of hydraulic conductivity were generated and combined with a numerical model to simulate water flow in an earth dam with variable K_{s} The firstorder secondmoment reliability index β was employed to characterize the influence of the variability of K_{s} and hence, porewater pressures, on the stability of the downstream slope. A linear relationship between σ_{lnKs} and the standard deviation of the factor of safety σ\dF was obtained from the simulation results. A relationship between β and σ_{lnKs} in which every 0.1 increment of σ_{lnKs}results in a decrease of 1.0 in β, is deduced based on the simulation results. Results of a ShapiroWilk test for goodnessoffit indicate that the factor of safety can be assumed to be normally or lognormally distributed when the saturated hydraulic conductivity follows a lognormal distribution and σ_{lnKs}is small (< or = 0.5). When σ_{lnKs}is large (>0.5), neither normal nor lognormal distributions provide a reasonable approximation of the factor of safety. Simulation results show that nether standard deviation nor coefficient of variation of the factor of safety is constant when only the variability of hydraulic conductivity is considered. While the results presented are directly applicable only to the particular earth dam geometry and boundary conditions studied, the methodology is general and may be extended to embankments with different boundary conditions. 
