| To prevent contamination of groundwater, geosynthetic liner systems are widely used to provide an impermeable barrier along the base of solid waste impoundments (landfills). However, the low interface shear strengths of geosynthetic liners can result in potential slope stability problems. After the failure of Kettleman Hills Landfill in 1988, the importance of landfill slope stability has become a topic of considerable importance in geotechnical engineering practice.; The objectives of this research were: (1) To understand the unique features of the landfill slope stability problem; (2) To develop a three-dimensional analysis procedure for evaluating slope stability of landfills; (3) To define a suitable scalar measure of stability (factor of safety) that would be applicable to the proposed procedure: (4) To verify the accuracy of the new procedure by re-evaluating the Kettleman Hills landfill failure; and (5) To identify hypothetical landfill configurations with pronounced three-dimensional effects.; A series of laboratory model tests were performed to provide a basis for understanding some of the unique features of the landfill slope stability problem. Internal failure surfaces that develop at the intersections of planar liner failure surfaces were observed to significantly impact the stability of landfill slopes.; A landfill slope stability analysis methodology based on linear elastic finite element analysis, named FLE-3D, was developed. The procedure accounts for the unique features of the landfill slope stability problem. The procedure is based on a force based definition of factor of safety that is applicable to stress-deformation based analysis, and accounts for the failure mechanism. The procedure was validated using the results of the laboratory model tests and case histories. Application of the FLE-3D analysis procedure to the Kettleman Hills landfill suggested that three-dimensional factor of safety was critical, and that the residual strength was mobilized along the liner system.; The three-dimensional factor of safety was found to be more critical than the two-dimensional factor of safety for narrow landfill configurations with compressible fill material or for landfills with diverging geometric conditions. The three-dimensional effects were controlled by the kinematics of the failure mechanism, rather than the geometry of the slope and failure surface. |
