Modelling volumetric and strength behaviours of sheared contact zone between dam soils

Interface behaviour between different granular material layers in geotechnical works, such as embankment dams, can affect their overall behaviour. Soil–structure interfaces have been widely studied but few analyses of soil–soil granular interfaces have been conducted. Therefore, there is a need to properly predict their behaviour. The mechanical behaviour of an interface zone between embankment dam materials, a core and a filter soils, is numerically studied during a laminar simple shear test. The main objectives are to properly reproduce the shear strength of interface layer and its deformation, including the volumetric behaviour. The interface behaviour is analysed based on hypotheses related to the interface zone, to the contact reproduction between the soil layers, and to the constitutive models used for the soils and their contact. The modelling of the shear test is performed to highlight the important aspects to consider in numerical simulation of granular interface layer. Using a model for granular soils based on the critical state concept (NorSand model) allows for prediction of the soil–soil interface shear strength and especially its volumetric deformation.