Holistic Simulation of Geotechnical Installation Processes

Volume 82 of the series Lecture Notes in Applied and Computational Mechanics pp 324-340


Constitutive Model for Viscous Clays Under the ISA Framework

  • Merita TafiliAffiliated withInstitute of Soil Mechanics and Rock Mechanics, Karlsruhe Institute of Technology Email author 
  • , Theodoros TriantafyllidisAffiliated withInstitute of Soil Mechanics and Rock Mechanics, Karlsruhe Institute of Technology

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The ISA-plasticity is a novel approach based on the intergranular strain concept. It introduces a yield surface within the intergranular strain space. The intergranular strain is related to the recent strain history, which is used to improve the model performance for cyclic loading. This paper proposes an ISA model for the simulation of saturated clays incorporating also possible viscous effects that clays may have. These rate-dependent phenomena are described within a viscous strain rate, which is added to the model besides the elastic and (hypo)plastic one. Possessing the plastic strain rate independent from the viscous strain rate the model is able to describe both viscous and non-viscous clays. At the beginning the formulation of the model is described. Subsequently, some explanation about the numerical implementation and the required parameters is given. Finally, the model is evaluated through some simulations with a Kaolin clay, which are compared with experimental results of laboratory tests. The simulations include oedometric and triaxial tests under monotonic and cyclic loading. The monotonic tests include also strain rate variation to evaluate the rate dependence of the proposed model.


Viscous clays Unsaturated clays Constitutive model ISA plasticity Intergranular strain