The authors combine random field generation and finite-element techniques to model steady seepage through a three-dimensional (3D) soil domain in which the permeability is randomly distributed in space. The analyses concentrate on the classic problem of steady seepage beneath a single sheet pile wall embedded in a finite layer of soil. Soil permeability is treated as a spatially random property with specified mean, variance, and spatial correlation length. The influence of the spatial correlation or "scale of fluctuation" is given special attention, since this aspect is not always included in probabilistic geotechnical analysis. The value of permeability assigned to each element comes from a lognormally distributed random field obtained from local averages of a normally distributed random field. Local averaging permits the element dimensions to be considered rationally on a statistical basis. The influence of three-dimensionality is given special emphasis and contrasted with findings obtained using an idealized two-dimensional model. For the complex 3D finite-element analyses, strategies are provided for optimizing the efficiency of the code in relation to memory and central processing unit requirements. Monte Carlo simulations are performed to establish statistics relating to quantities of interest to designers, such as the flow rate. The potential value of this approach can be seen when the results are presented in the context of reliability-based design.


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  • Accession Number: 00735021
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 9 1997 12:00AM