Nonlinear deformation analyses of liquefaction effects on embankment dams

Abstract

Nonlinear deformation analyses (NDAs) are used for evaluating the potential effects of liquefaction on the seismic performance of embankment dams. NDAs provide insights on potential failure modes and serve as a basis for generating fragility curves for risk analyses. Confidence in these applications of NDAs may be significantly improved by establishing calibration and analysis protocols that reduce undesirable sources of variability between analysis results obtained by different analysts or different models. A key protocol for improving the quality of NDAs is the calibration and validation of a constitutive model using single-element simulations with the types of loading paths potentially important to the structure's response. These simulations provide a basis for evaluating the strengths and weaknesses of the constitutive models and for identifying likely causes of differences between different modeling approaches. Examples of single-element simulations are presented for several constitutive models and loading paths to illustrate some of the important features for NDAs of embankment dams affected by liquefaction. The benefits of NDA studies also depend on the numerical procedures and results being sufficiently documented so that knowledgeable users can critique and interpret the results. Insights from parametric analyses should be adequately demonstrated so that members of the project team can exercise judgments regarding their practical implications. Recommendations on NDA documentation requirements are presented, along with an example of how such documentation can be important for the interpretation of NDA results. Critical examinations of NDA models and modeling procedures are necessary for identifying weaknesses, fostering improvements, and increasing confidence in their use for evaluating the seismic performance of embankment dams affected by liquefaction.