The influence of gravel-scale heterogeneity and scale effect on the mechanical properties of conglomerate

Heterogeneity is a prominent characteristic of conglomerates, which will significantly influence the mechanical properties. Gravel petrological characteristics are the key factors in quantifying the heterogeneity of conglomerates, which also produces a conspicuous scaling effect on mechanical properties. To systematically examine the heterogeneity and scale effect of the conglomerates, we propose a random generation algorithm and reconstruct the two-dimensional conglomerate samples with statistical consistency, based on the discrete element model. Numerical tests on samples with different scales are conducted to reveal the effects of petrological characteristics and the sample scale. The increases in gravel sorting, gravel size, slenderness ratio, and gravel content improve Young’s modulus, while the increase in the gravel sorting and gravel content weakens the uniaxial compressive strength. Conglomerate with slender gravels, high content, good sorting, and small gravel size tends to form dispersed and complex fracture networks. Most failures happen in or near the gravels in tensile mode and a few micro shear cracks are distributed at the interface. Uniaxial compressive strengths of conglomerates conform to a power law descending trend with the increase in the sample size, while the modulus dispersion converges quickly. The inclined main fracture becomes more prominent and smoother with increasing sample size.