Influence of microscopic parameters on the macroscopic mechanical response of sand

In order to study the influence of microscopic parameters on the macroscopic mechanical response of sand, the discrete element software PFC3D is used to establish the numerical model of the triaxial test of sand in this paper, the indoor triaxial test of sand is carried out to calibrate the numerical model. The triaxial tests are finished under the conditions of confining pressures of 100 kPa, 200 kPa, 300 kPa, and 400 kPa, respectively. The influence of the microscopic parameters on the macroscopic mechanical response of the sand is analyzed, the orthogonal experimental method is used to study the sensitivity of the numerical model to microscopic parameters such as porosity, flexible boundary stiffness, normal tangential stiffness ratio, and friction coefficient. The results show that the peak strength and residual strength of the stress-strain curve of sand are most affected by the friction coefficient, they are positively correlated with the friction coefficient under different confining pressures. The normal tangential stiffness ratio is negatively correlated, it is less affected by porosity and boundary flexibility stiffness, the sensitivities of different microscopic parameters are analyzed through the orthogonal tests, the results of orthogonal tests and numerical simulations show the consistent patterns in terms of sensitivity to microscopic parameters. The results can provide the reference for the influence of microscopic parameters and the macroscopic mechanical response of sand.