S_BRICK: a constitutive model for soils and soft rocks

Materials known in the literature as hard soils and soft rocks are widely spread, natural materials that are commonly encountered in engineering practise. It was demonstrated that some of these materials can be described through the general theoretical framework for structured soils set by Cotecchia and Chandler [14], which takes into account the structure as an intrinsic property present in all natural geological materials. Based on laboratory results and existing theoretical frameworks, the development of a constitutive model for structured materials was carried out. The model formulated in strain space named BRICK [27, 29] was chosen as the base model and was further developed by adding features to model both the structure and the processes of destructuring. The new model was named S_BRICK and was first presented on a conceptual level, in which the typical results of modelling structured and structureless (reconstituted) materials on different stress paths were compared within the solutions of the Cotecchia and Chandler [14] theoretical framework. The S_BRICK model was validated on three materials, i.e., Pappadai clay, North-Sea clay and Corinth marl, thus covering a wide range of natural, structured materials. The results showed that S_BRICK was able to successfully model the stress-strain behaviour typical for hard-soil and soft-rock materials, in general.