DEM multi-scale insights on the pre-failure behavior of mature structured sands: Influence of bond type, amount, breakage pattern and heterogeneity

A new approach in the calibration process of DEM samples of structured sand is presented. Micromechanical-based experimental data are interpreted to develop a failure model and a range of input parameters in the DEM analyses are incorporated considering strong and a weak bonds in the simulated samples. Subsequently, the numerical samples correspond to analog mature structured soil/sandstone in terms of both compositional and textural maturity, and the study focused on the small-to-medium strain shear modulus and on providing multi-scale insights of the simulated materials. The heterogeneity of the structured sand is incorporated based on Gaussian and Weibull distributions of the contact properties and four major parameters are examined including bonding amount/content, bonding strength, heterogeneity, and confining pressure. The numerical results showed, at the macroscopic level, agreement with respect to a number of element-size experiments on sandstones which were re-analyzed in the present work, in terms of stiffness—pressure relationship, stiffness reduction, and occurrence of the yield point associated with the initiation of bond breakage. It was shown that even though the bond strength and amount of bonds are important influencing factors on the macroscopic behavior of the structured sand, the incorporation of heterogeneity can significantly alter the interpretations of the microscopic involved mechanisms. This unveils that the implementation of “average” input parameters cannot capture well the contributing mechanisms which influence the deformation characteristics of structured soils and sandstones. © 2023 John Wiley & Sons Ltd.