Constitutive modelling of viscous behaviour of soils: A case study

• Visco-elastic and visco-plastic, 1D constitutive model.
• Two deformation mechanisms for elastic and plastic deformations.
• Effects of viscous deformations during primary consolidation.
• Simulation of viscous effects in inorganic and organic clays.
• FEM analyses of an embankment built on compressible, organic soils.

An innovative constitutive 1D rheological model is proposed for simulating the visco-elasto-plastic behaviour of geological materials. The principal innovative aspect of this model is the identification and the calibration of two mechanisms of deformation: the first one is a short term mechanism, whereas the second one is a long term mechanism. In this work the first mechanism is considered as perfectly instantaneous and the implications of this assumption are firstly examined with reference to typical laboratory test results. Model simulations are then compared with the settlements history measured below a 8.00 m high embankment, built on organic soils and subjected to nearly 1.00 m large settlements in less than one year.