Internal Friction Angles: Characterization Using Biaxial Test Simulations

The internal angles of friction for cohesionless assemblies of particles under compression were determined using molecular dynamics type simulations of biaxial tests. The objective was to determine appropriate internal friction angles to be used for continuum modelling of broken ice covers on waterways. The particles were modelled as random-sized circular disks. Constant confining pressures as well as a constant displacement rate were used for the biaxial tests. The stress-strain curves were obtained for a range of confining pressures. The yield envelopes follow a Mohr-Coulomb criterion of failure. The effect of the interparticle friction coefficient on the global angle of friction was examined. It was found that the internal angle of friction was essentially independent of the interparticle friction angle. Furthermore, assemblies with different particle size distributions were used in order to investigate the effects of this parameter on the internal angle of friction. It was found that as the particle size distribution is made wider, the magnitude of the internal angle of friction increases. Finally, the results obtained using two different contact models were compared in order to verify the effect of this parameter on the results.