MICROMECHANICS SIMULATION OF DIRECT SHEAR TEST OF SANDY PEBBLE SOIL WITH DISCRETE ELEMENT METHOD

As a special geotechnical material，sandy pebble soil was studied by more and more researchers． Direct shear test numerical models of sandy pebble soil were built with the help of discrete element method in threedimension， and the numerical results were compared with the experimental data． As sandy pebble soil was not continuous medium in three-dimension with arbitrary shapes，in order to study its shear characteristics better， polyhedral particles were created to simulate sandy pebble soil approximately． The results were compared with the results came from traditional spherical particles simulation． The results showed that polyhedral particles overcame the defect of spherical particles，the simulation with polyhedral particles could reflect the direct shear phenomenon better and be more consistent with the experimental data． Analysis of microparameter sensitivity showed that the peak segment of shear curve was mainly affected by the contact stiffness and the friction coefficient，while the rising speed of shear curve was mainly affected by the contact stiffness．