Abstract

The paper presents classical and non-classical rheological schemes used to formulate constitutive models of the one-dimensional consolidation problem. The authors paid special attention to the secondary consolidation effects in organic soils as well as the soil over-consolidation phenomenon. The systems of partial differential equations were formulated for every model and solved numerically to obtain settlement curves. Selected numerical results were compared with standard oedometer laboratory test data carried out by the authors on organic soil samples. Additionally, plasticity phenomenon and non-classical rheological elements were included in order to take into account soil over-consolidation behaviour in the one-dimensional settlement model. A new way of formulating constitutive equations for the soil skeleton and predicting the relationship between the effective stress and strain or void ratio was presented. Rheological structures provide a flexible tool for creating complex constitutive relationships of soil.

Highlights

  • Soil is a complex porous three-phase material in which many phenomena take place simultaneously

  • By applying rheological schemes to model the behaviour of the soil skeleton and coupling them with the equation of pore water flow, it is possible to describe the transient response of soil taking into account secondary consolidation of viscoelastic soils [7,8,9,10,11,12]

  • Gibson and Lo [8] presented an analytical solution of one-dimensional consolidation in which the relationship between the effective stress and vertical strain was formulated according to the standard model

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Summary

Introduction

Soil is a complex porous three-phase material in which many phenomena take place simultaneously. By applying rheological schemes to model the behaviour of the soil skeleton and coupling them with the equation of pore water flow, it is possible to describe the transient (time-dependant) response of soil taking into account secondary consolidation of viscoelastic soils [7,8,9,10,11,12]. It should be noted that the presented procedure can be applied for any viscoelastic rheological structures This shows that the great potential of constitutive models developed in different research fields can be straightforwardly utilized to solve geotechnical problems. The simple linear relationship between the effective stress and strain (Equation (2)) does not take into account secondary consolidation to be observed in organic or soft clay soils This can be shown by comparison of the model prediction with oedometer laboratory test data carried out on a remoulded sample of soil with about 7% organic matter content (see Figure 2).

Classical Rheological Schemes for Consolidation
Burgers Model for Soil Skeleton
Numerical Solution
Kepes Element for Effective Stress Behaviour
Formulation
Discussion
Conclusions
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