A MULTILAMINATE MODEL WITH DESTRUCTURATION CONSIDERING ANISOTROPIC STRENGTH AND ANISOTROPIC BONDING

Vahid Galavi and Helmut F. Schweiger

ABSTRACT: Many constitutive models have been developed to describe the behaviour of soils, but only more recently a limited number of them have paid attention to include effects of structure and consequently destructuration due to volumetric and/or deviatoric straining. Most of them consider isotropic behaviour for strength and structure of soil. In this paper a multilaminate type of constitutive model is presented in which anisotropic strength and anisotropic structure are taken into account. According to the mathematical formulation of the multilaminate framework, this kind of model is capable of taking into account induced anisotropy intrinsically. Inherent anisotropy can be introduced to the model by varying the model properties over sampling planes using a so-called microstructure tensor. Only mechanical destructuration, namely degradation of structure with deformation is considered in this paper. The proposed model is capable to consider anisotropy in bonding and preconsolidation pressure as well as inherent anisotropy in strength thus the hardening of the yield surface and strength parameters can be considered direction dependent. In this paper the drained and undrained behaviour of natural clays is simulated and the effect of different assumptions with respect to structure degradation and anisotropy is evaluated.

Key words : constitutive modelling, destructuration, multilaminate model  (IGC: D6/E1/T6)