Reliability of embankments on soft ground using constrained optimization

B. K. Low
School of Civil and Structural Engineering, Nanyang Technological University, Singapore
Wilson H. Tang
Department of Civil and Structural Engineering, Hong Kong University of Science and Technology, China

A common failure mechanism of embankments constructed on soft clay is that of rotation along nearly cylindrical slip surface. The limit equilibrium methods of slices such as Bishop’s simplified method have been widely used to assess stability by computing the factor of safety, defined as the ratio of the available shear strength to the shear stress required to maintain equilibrium. Partly because of the iterative and implicit nature of the computation and the need to search for critical slip surface, most practitioners are satisfied with the deterministic factor of safety evaluation instead of adopting a more logical reliability analysis which accounts for uncertainty.


The deterministic limit equilibrium formulation is described first as it provides the performance function needed for subsequent reliability analysis. Alternative deterministic formulations are covered comprehensively in Fredlund and Krahn (1977), Nash (1987), and Li (1992), among others. Reliability and risk assessment of slopes have been dealt with by Li and Lumb (1987), Tang (1993), Morgenstern (1997), Low et al. (1998), for example.

References

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