Elastic visco-plastic consolidation modelling of clay foundation at Berthierville rest embankment

This paper applies for the first time a highly non-linear One-Dimensional E lastic Visco-Plastic (I-D EVP) model to the consolidation analysis of the c lay layer underneath Berthierville test embankment in Quebec, Canada. This paper firstly gives a brief description of the main equations of the Finite Element (FE) consolidation modelling incorporating the I-D EVP model. Spec ial issues encountered in the consolidation modelling of the field problem are addressed. Water head fluctuations at the upper and lower boundaries of the clay are considered by giving an appropriate definition of excess pore water pressure. An optimization procedure is suggested for the determinatio n of the 1-D EVP model parameters. The determination of initial strains in the held is explained. The FE model can consider (a) multi-layered soil pro file, (b) time-dependent loading and hydraulic boundary conditions and (c) different constitutive models for different soils (1-D EVP model for clay a nd Terzaghi's model for silty sand). A parametric FE modelling study is car ried out to determine two uncertain parameters of the silty sand layer unde rlying the clay layer. It is found that the parameter m(v) affects the comp ressibility of the silty sand layer, but has no influence on the consolidat ion behaviour of the clay. However, the parameter k can affect the compress ion of the silty sand layer and the clay layer. FE consolidation modelling of the soils underneath Berthierville test embankment is carried out using the model parameters determined. It is found that the compression of the cl ay layer computed from the FE model is in good agreement with field measure d values. Porewater pressures from the FE modelling are close to the measur ed values except for the values at the initial loading stage. This discrepa ncy at this initial stage is discussed in this paper. Copyright (C) 2000 Jo hn Wiley & Sons, Ltd.