UC Davis

Two methods to account for strain rate dependence of clay behavior in computing settlement due to consolidation and secondary compression are compared. The first method explicitly accounts for strain rate effects during primary consolidation using a visco-plastic relationship and nonlinear finite difference solution. The second method indirectly accounts for strain rate effects during primary consolidation by using analytical solutions for consolidation and secondary compression in combination with a time-line based procedure for selecting the analysis parameters. The second method is computationally simpler, and potentially useful for more complicated soil layering and loading conditions. These two analysis methods are described, along with a third, traditional approach for comparison. Results are presented for one-dimensional analyses of a single clay layer for a range of stress history and loading conditions. The time-line based method is shown to provide a reasonable approximation of the more rigorous nonlinear analysis method, indicating that various traditional analysis methods can approximately account for strain rate effects (or creep) during primary consolidation through the appropriate selection of input properties.