Effect of Interparticle Friction and Particle Elasticity on Behavior of Granular Materials

This study evaluates the influence of the inter-particle friction coefficient and particle elasticity on the critical state behavior of granular assembly using an open-sourced software, YADE. A range of mu between 0 and 0.5 has been used in the literature, with most studies with mu of 0.5. However, some studies suggested mu should be less than 0.5 to avoid an unusual increase in void ratio at the critical state with increasing mean effective stress (p'), while others did not observe that. This study evaluates whether the anomaly of the observation is due to the combined effect of interparticle friction and particle elasticity (E). A series of 90 DEM simulations have been performed using mu of 0.3 and 0.5 and E of 50 MPa and 100 MPa for both drained and undrained simulations up to 30% strain to observe the critical state behavior. The mu and E both influence the critical state behavior of the granular assemblies. Whereas the interparticle friction influences the vertical shifting of the CSL, the particle elasticity influences the horizontal shifting of the CSL with increasing mean effective stress. The larger value of mu increases the critical state void ratio (shift the CSL upwards), and low value of mu decreases the critical state void ratio (shift the CSL downwards) irrespective of the value of the E. The E, on the other hand, does not affect the CSL for low values of mean effective stress (p'<= 20 kPa) for granular assemblies with the same mu. However, for higher values of mean effective stress (p'> 20 kPa), the slope of the CSL horizontal increased for higher values of E of granular materials.