Hydromechanical Tensile Strength Modelling at Particle Size Level for Non Cohesive Granular Materials

The aim of this paper is to propose a robust yet simple model to predict the variation of the tensile strength of granular materials with the degree of saturation. Because capillary phenomenon and air-water surface tension govern interparticle bonding in granular materials, they are explicitly taken into consideration. These vary with the degree of saturation as with all geotechnical structures that are subjected to wetting-drying processes. To predict the influence of capillary and air-water surface tension effects, mathematical equations are derived to simulate a porous model. The model is used to predict the drainage process in the porous network of the material and thus determine the relationship between interparticle bonding and the degree of saturation of the granular material. These hydraulic processes are expressed in mechanical terms using the effective stress concept thus providing the key for hydromechanical coupling. The parameters for the resulting equations can be obtained from conventional well-known laboratory tests: the water retention curve, the grain-size distribution of the material and its void ratio. The numerical results are confronted to laboratory tests showing that this approach predicts accurately the tensile strength of granular materials.