Finite element analysis of consolidation of layered clay soils using an elastic visco-plastic model

This paper presents a general one-dimensional (1-D) finite element (FE) pro cedure for a highly non-linear 1-D elastic visco-plastic (1-D EVP) model pr oposed by Yin and Graham(1,2) for consolidation analysis of layered clay so ils. In formulating the 1-D FE procedure, a trapezoidal formula is used to avoid the unsymmetry of the stiffness matrix for a Newton (modified Newton) iteration scheme. Unlike many other 1-D FE approaches in which the initial in situ stresses (or stress/strain states) are considered indirectly or ev en not considered, the initial in situ stress/strain states are taken into account directly in this paper. The proposed FE procedure is used for analy sis of 1-D consolidation of a clay with published test results in the liter ature. The FE modelling results are in good agreement with the measured res ults. The FE model and procedure is then used to analyse the consolidation of a multi-layered clay soils with a parametric study on the effects of the variations of creep parameters in Yin and Graham's 1-D EVP model. It is fo und that the creep parameters psi/V and t(0) have significant influence on the compression and porewater pressure dissipation. For some boundary condi tions, changes of parameters in one layer will have some effects on the con solidation behaviour of another layer due to the different consolidation ra tes. Finally, the importance of initial stress/strain states is illustrated and discussed. Copyright (C) 1999 John Wiley & Sons, Ltd.