Development and Application of Dynamically Similar Model Materials for Blasting in Reef Limestone

To address the difficulty of sampling reef limestone and poor dynamic replication by conventional similar materials, this study introduces wave impedance as a key dynamic index for designing similar materials for reef limestone blasting. An orthogonal experiment examined five parameters: barite powder content, aggregate-to-binder ratio, cement-to-gypsum ratio, foaming agent dosage, and fiber content, using range and linear regression analyses. The optimal mix was used to prepare similar materials for SHPB and single-hole blasting tests. High-speed photography and DIC compared crack and strain evolution under single- and three-hole blasting. Results show that the aggregate-to-binder ratio dominates density, while it and foaming agent dosage jointly govern porosity. The cement-to-gypsum ratio controls compressive and tensile strength, while wave velocity is jointly determined by barite powder content, aggregate-to-binder ratio, and foaming agent dosage. Key indices of the optimal material show relative errors below 10% versus the prototype rock. Dynamic peak stress, fragmentation fractal dimension, and macroscopic fracture morphology are generally consistent. Under multi-hole blasting, the peak maximum principal strain between holes is 1.46 times that under single-hole blasting. After normalization by total charge, the final crack length per unit charge under three-hole blasting is 1.52 times that under single-hole blasting, forming a penetrating failure zone, indicating synergistic enhancement rather than linear superposition. These findings provide a material basis and data reference for reef limestone blasting research.