This grant supports research that looks to advance the knowledge of how fluid-coupled granular media behave. Because granular media are ubiquitous in natural systems (such as soils in riverbeds and landslides) and infrastructure (such as concrete and ballast), this research will promote both the progress of science and engineering, as well as advance national prosperity. When a load is applied to a granular medium, such load is transmitted via a network of forces among grains that are in contact. This network of forces, or force chains, is the ultimate determinant of how granular media behave under external loading (e.g., compression and shear) and under fluid injection and withdrawal. Understanding the spatial structure and temporal evolution of force chains constitutes a fundamental goal of granular mechanics. However, the current knowledge of granular media is limited by the experimental observations on force chains, which are either on two-dimensional packs or on three-dimensional packs with limited grain shapes or loading conditions. The coupling between the solids and fluids in granular media adds yet additional complexity for observations and modeling. This award supports fundamental research looking to advance experimental techniques and the associated theory for fluid-coupled granular media, enabling the observation of the transmission of external loads on both the single-grain scale and the granular pack scale. The outcomes of this research intend to provide new kno