Studies on structural and mechanical properties under isostatic compression with large-scale discrete element simulations

Granular systems undergo a jamming transition at point J simply by increasing the packing fraction. A large-scale parallel discrete element code (THDEM: TsingHua Discrete Element Method) was used to obtain a satisfying statistical description of the structural and mechanical properties near point J. The isostatic compressions of 100,000 polydispersed frictionless particles were simulated on high performance computers to clearly observe the sophisticated configurations of force chains. The first peak of the pair correlation function, coordination number, spatial distribution of the packing fraction, and stress were calculated to analyze their variations with increasing packing fraction. The critical packing fraction at point J is determined to be 0.62. The incremental stress and coordination number from point J scale well with the power law, and coincide with previous theoretical predications. The distribution of the packing fraction is a normal distribution around the average value. The standard deviation decreases with increasing packing fraction, indicating the system is more uniform with a denser packing.