<p>Focusing on the mechanical characteristics of calcareous sand under explosive loading, parameters for a visco-hypoplastic constitutive model incorporating strain rate effects were obtained based on SHPB impact tests. Experimental investigations were carried out on the propagation characteristics of blast stress waves in coral sand with varying densities and different charge masses. The propagation behavior of blast-induced stress waves in coral sand was analyzed, and the attenuation law and underlying mechanisms were further revealed through numerical simulations. The following conclusions were drawn: (1) The simulated attenuation of blast stress waves shows a deviation of less than 10% from experimental results, verifying the accuracy of the constitutive model and parameter selection. (2) In contact blasts, the peak stress in coral sand is significantly lower than that in buried blasts. When the burial depth exceeds the charge diameter, the scaled burial depth has minimal influence on the attenuation of peak stress. Instead, the primary energy dissipation is attributed to the ejection and deformation of the upper sand layer. (3) The influence of relative density on the attenuation of blast stress waves in sand is complex. In the near-field region of the blast, loose sand mainly dissipates energy through compression, while dense sand does so through particle crushing. Consequently, the near-field peak stress first increases and then decreases with increasing relative density. In the far-field region, the effect of density becomes negligible. (4) Under the same charge mass and burial depth, the attenuation behavior of blast stress waves differs between coral sand and silica sand. Due to its higher crushability and porosity, coral sand exhibits lower peak stress and a slower attenuation rate than silica sand. Thus, coral sand demonstrates superior energy dissipation performance and is more effective as a wave-mitigating dispersive layer.</p>