Effects of Concavity and Convexity‐Induced Anisotropy on the Elastic Modulus and Sound Velocities of Granular Soils

ABSTRACT The study of elastic moduli and stress properties in granular systems is crucial for understanding seismic triggering and geological structure inversion. This study uses discrete element method simulations to investigate the influence of shape concavity and convexity on the elastic moduli and stress distribution in granular systems, where both elliptical (convex) particles and cardioid (concave) particles are considered with equal area and eccentricity. The compression and shear wave velocities of elliptical and cardioid particle systems are calculated using the time‐of‐flight method. The results show that in systems of similarly shaped cardioid and elliptical particles, the sound velocity of elliptical particles was consistently higher than that of cardioid particles. To understand these discrepancies, a statistical analysis is conducted on the distributions of contact normal vectors, stress, and elastic moduli within the systems. These quantities are expanded using irreducible tensor bases, thereby calculating anisotropy values accurate up to the 8th‐order. Changes in particle shape have a considerable impact on the elastic moduli and stress distribution. Furthermore, variations in moduli and stress effectively elucidate the alterations in sound velocity with particle shape. In addition to elucidating the influence of shape on the constitutive relationships of granular materials, this study also provides invaluable insights for the design of acoustic materials.