Analysis of seepage erosion and stability problems in geomechanics
AuthorGobin, Roger Siad, 1966-
MetadataShow full item record
PublisherThe University of Arizona.
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AbstractIn this study, a two dimensional finite element model is developed to analyze the effects of seepage and traction on slope stability. The finite element model was used to determine the failure mechanisms associated with tractive and seepage induced failures. Limit equilibrium models were then developed to model both seepage and tractive erosion based on the failure mechanisms indicated by the finite element model. A conceptual model to qualitatively predict the effects of changes in flow regime on the stability of sandbars within recirculating zones was also developed. The finite element model uses Biot's coupled stress-pore water pressure theory to simulate the effects of transient loading conditions on the stresses, phreatic surface variations and displacements within a soil mass. The finite element model's simulations of various events recorded on Grand Canyon sandbars compared favorably with field data. A limit equilibrium model to simulate seepage effects on homogeneous slopes was developed. It is shown that at the seepage surface, the magnitude and direction of the seepage vector are uniquely related and are not independent variables as was previously assumed in the literature. Seepage parallel to the slope is shown to result in the minimum stable seepage slope. Static liquefaction is shown to be possible for a range of seepage directions, depending on the unit weight of the soil. The conceptual model relates the qualitative effects of changes in the flow regime to the geometry of sandbars within recirculating zones. The effects of changes in discharge on the characteristics of the recirculating zones are related to sandbar stability. The predictions of the conceptual model compared favorably with the observed behavior of Grand Canyon sandbars.
Degree ProgramGraduate College
Civil Engineering and Engineering Mechanics