Seismic Analyses of an Earth Dam Using the Boundary Surface Plasticity Model

Abstract

This investigation presents coupled analysis of an earth dam problem including all aspects of fluid-structure interaction (class I coupling) and soil-pore fluid-structure interaction (class II coupling) under earthquake excitations using the finite element method and its comparison with the coupled one. New software for predicting and analyzing coupled behavior is established using the pressure formulation for modeling of the fluid and the u-p formulation for modeling of the soil-pore fluid. The staggered partitioned solution technique for coupled field problems is implemented and used in the computer code. This scheme is incorporated in terms of a sequential execution for single-field analyzers. The bounding surface plasticity model is used as a constitutive relationship for modeling the clay core of a dam made up of Boston blue clay first and Baghdad brown silty clay later. The general theoretical farme work of the model and its numerical implementation with emphasis on isotropic cohesive soils are given. Also, the input material parameters are identified and the tests required for determining these parameter s are clarified on Baghdad brown silty clay. Implicit-Implicit Newmark’s numerical integration of the equations of motion.The results show that the bounding surface plasticity model can give a logical impression for the behavior of clayey soils under dynamic loads. Also, the earthquake design of structures generally and dams in particullr, must take into account various interactions between the foundation, the structure and the water in the reservoir in addition to site effects. Amplifications due to stratification and dephasing (response lag) in the foundations of structures should also be considered.