Structure Degradation of Dry Aggregated Soils: Experimental Evidence and Model Formulation

Aggregated soils, such as agricultural soils, are under consideration as representatives of structured soils with double structure, including macro and micro porosity. In this paper, the main characteristics in compression behaviour of these soils are first addressed. The possible mechanisms of structure degradation are presented with special emphasis on the role of microstructure. The experimental technique of neutron tomography followed by image processing is used to quantify structure degradation during compression. A state parameter is introduced to describe the soil structure degradation and an evolution law is proposed as a function of the associated plastic strains. This parameter is then used to develop a compression model formulation and to propose an evolution rule for the apparent preconsolidation pressure for aggregated soils.