Effect of heterogeneity of particle properties on variability of laboratory sandy soil properties: A random discrete element perspective

Abstract

Many experimental results have presented that soil deformation and strength properties for the same type of soil samples are with a certain variability at the same density and stress states, and even at the identical laboratory conditions. Micro mechanical interpretations of this phenomenon are the random spatial arrangement of constituent particles and heterogeneity of particle geometry and mechanical properties. This paper mainly focuses on the influence of the latter, which is still an open issue for the community of granular materials, by the random discrete element method. The random field model is firstly incorporated into the discrete element method to characterize the heterogeneity of equivalent particle properties for a simple linear rolling resistance contact model. Two RFM parameters named coefficient of variation and scale of fluctuation are adopted to represent the variability and spatial correlation pattern of particle properties, respectively. Monte Carlo simulations are then performed by repeatedly conducting DEM simulations of drained triaxial compression tests on a series of dense heterogeneous specimens. The macroscopic soil deformation and strength parameters are analyzed statistically. The contact network characteristics of three representative heterogeneous specimens are discussed and compared with those of the homogenous specimen to explore the underlying microscopic mechanisms. Moreover, the variability of soil properties due to the random spatial arrangement of constituent particles is compared with that due to the heterogeneity of particle properties. The study helps to provide more insights into the cross-scale understanding of the variability of sandy soil properties in the laboratory.