Effects of grain shape angularity on cohesive strength in sheared granular media

Using extensive Contact Dynamics simulations, we present a systematic analysis concerning the effects of particle shape angularity on the quasi-static shear strength properties of cohesive granular packings under biaxial conditions for various confining stresses σ0. We consider irregular polygons with an increasing number of sides, ranging from triangles to discs. The packings behavior depends on the dimensionless Cohesive Index η = f0/(σ0d), where f0 is the contact adhesive force and d is the mean grain diameter. η is varied between 0 (dry) to 0.6 (strongly cohesive) by varying σ0. We find that the macroscopic friction angle increases with grain angularity and saturates at larger angularity, as in the dry case. In contrast, the cohesive strength is an increasing function of grain angularity. Our results contribute to a better understanding of the effects of grain shape on the behaviour of cohesive granular materials, by complementing a number of results obtained mainly in the dry case.