Applications of Adaptive Time Stepping in Analysis of Biot Consolidation

The accuracy of finite element solutions for the consolidation of porous media is influenced by the number and size of the time increments used in the analysis. A solution algorithm for adaptively selecting time increments for the solution of elastic and elastoplastic coupled consolidation problems in finite element analysis has been developed by Sloan and Abbo (1999). By treating the governing consolidation relations as a system of 1st-order differential equations their algorithm utilized subincrementation to automatically adjust the size of time increments used in the analysis. Unlike other time stepping schemes, the procedure adjusts the time increments in order to control the error due to time stepping to lie near a specified tolerance. The algorithm was shown to be robust and to provide an efficient method for the solution of consolidation problems. In this paper the efficiency of the algorithm is further demonstrated through the analysis of the construction of an embankment on a deep layer of soft soil. The time increments required for the efficient and accurate analysis of the consolidation of porous media are shown to differ by orders of magnitude.