We investigate the rheology, force transmission and texture of granular materials composed of elongated particles by means of contact dynamics simulations. The particles have a rounded-cap rectangular (RCR) shape described by a single elongation parameter varying from 0 for a circular particle to 1 for an infinitely thin or long particle. We study the quasi-static behavior, structural and force anisotropies as a function of the elongation parameter for packings submitted to biaxial compression. The shear strength is found to increase linearly with this parameter whereas the solid fraction both at the initial isotropic state and in the critical state is nonmonotonous. We show that for these elongated particles a harmonic decomposition of the stress tensor provides a fairly good approximation of the internal state. Our data suggest that the increase of shear strength with reflects both enhanced friction mobilization and anisotropic particle orientation as the elongation of the particles increases.

JF - 9th International Workshop on Bifurcation and Degradation in Geomaterials (IWBDG 2011) CY - MAY 23-26 2011 Porquerolles, FRANCE VL - Springer Series in Geomechanics and Geoengineering - ADVANCES IN BIFURCATION AND DEGRADATION IN GEOMATERIALS UR - https://hal.archives-ouvertes.fr/hal-00686728 ER - TY - Generic T1 - Modeling Porous Granular Aggregates T2 - 9th International Workshop on Buifurcation and Degradation in Geomaterials (IWBDG 2011) Y1 - 2011 A1 - Rafik Affès A1 - Vincent Topin A1 - Jean-Yves Delenne A1 - Yann Monerie ED - Stéphane Bonelli ED - Dascalu, Cristian ED - François Nicot AB -We rely on 3D simulations based on the Lattice Element Method (LEM) to analyze the failure of porous granular aggregates under tensile loading. We investigate crack growth by considering the number of broken bonds in the particle phase as a function of the matrix volume fraction and particle-matrix adhesion. Three regimes are evidenced, corresponding to no particle damage, particle abrasion and particle fragmentation, respectively. We also show that the probability density of strong stresses falls off exponentially at high particle volume fractions where a percolating network of jammed particles occurs. Decreasing the matrix volume fraction leads to increasingly broader stress distribution and hence a higher stress concentration. Our findings are in agreement with 2D results previously reported in the literature.

JF - 9th International Workshop on Buifurcation and Degradation in Geomaterials (IWBDG 2011) PB - Springer Netherlands CY - MAY 23-26 2011 Porquerolles, FRANCE VL - Springer Series in Geomechanics and Geoengineering - ADVANCES IN BIFURCATION AND DEGRADATION IN GEOMATERIALS SN - 978-94-007-1420-5 ER - TY - Generic T1 - Onset of Immersed Granular Avalanches by DEM-LBM Approach T2 - 9th International Workshop on Buifurcation and Degradation in Geomaterials (IWBDG 2011) Y1 - 2011 A1 - Jean-Yves Delenne A1 - Mansouri, M. A1 - Farhang Radjaï A1 - Moulay Saïd El Youssoufi A1 - Seridi, A. ED - Stéphane Bonelli ED - Dascalu, Cristian ED - François Nicot AB -We present 3D grain-fluid simulations based on the discrete element method interfaced with the lattice Boltzmann method and applied to investigate the initiation of underwater granular flows. We prepare granular beds of 800 spherical grains with different values of the initial solid fraction in a biperiodic rectangular box. In order to trigger an avalanche, the bed is instantaneously tilted to a finite slope angle above the maximum angle of stability. We simulate the dynamics of the transient flow for different solid fractions. In agreement with the experimental work of Iverson (Water Resour Res 36(7):1897–1910, 2000) and Pailha et al. (Phys Fluids 20(11):111701, 2008), we find that the flow onset is controlled by the initial solid fraction.

JF - 9th International Workshop on Buifurcation and Degradation in Geomaterials (IWBDG 2011) PB - Springer Netherlands CY - MAY 23-26 2011 Porquerolles, FRANCE VL - Springer Series in Geomechanics and Geoengineering - ADVANCES IN BIFURCATION AND DEGRADATION IN GEOMATERIALS SN - 978-94-007-1420-5 ER -