One-dimensional elastic viscoplastic finite strain consolidation model for soft clay with uncertainty

Abstract

Spatial variability of engineering properties caused by the natural characteristic heterogeneity is a common feature in soil layers. Meanwhile, changes in soil properties during consolidation and large strains are commonly encountered during long-term consolidation analysis of soft soils; however, few studies have considered these factors. A 1-D consolidation model fully coupled with elastic viscoplastic constitutive model, called EVPC, is developed using piecewise-linear method for long-term settlement of soft clay. The EVPC incorporates the idea of ‘equivalent time’ to account for large strain, soil self-weight, compressibility and permeability with spatial variability and high nonlinearity, as well as creep during the consolidation process. A comparison with finite element simulations and oedometer tests with different thicknesses of soil layer under multi-stage constant loads verified the effectiveness and accuracy of the EVPC’s deterministic analysis. After that, the long-term settlement and excess pore pressure distribution of Berthierville clay layer from the field test are estimated using EVPC probabilistic analysis. All measurements from the field test are within the range of corresponded closely to the high probability density results of the probabilistic analysis, and the excess pore pressure is revealed to be more sensitive to the spatial variability of soil parameters than settlement.