Pressure‐Dependent Elastic Moduli of Granular Media With Different Packing Modes and Cements

Elastic wave velocities and moduli are highly sensitive to tectonic stresses, making them valuable tools for monitoring subsurface tectonic activity. Natural rock behaves as a granular medium, where grain contact modes, cementation and third‐order elastic constants (3oECs) influence the relationship between stress and elastic moduli. This study integrates experimental measurements and numerical simulations to investigate the impact of these factors on elastic moduli. For sparsely packed, uncemented samples, stress and strain are concentrated at the air gaps between grains, resulting in increased compressibility and greater pressure sensitivity. The presence of cement alters the distribution of stresses and strains in these samples, enhancing stiffness and reducing pressure sensitivity. In contrast, for closely packed samples, the packing arrangement predominantly governs stress and strain distribution, diminishing the role of cement in modulating pressure‐dependent elastic moduli. For a given stress‐strain distribution, higher cement content increases elastic moduli while decreasing pressure sensitivity. The 3oECs of individual grains affect the effective elastic moduli of the granular medium only when strain is directly applied to the grains.