Small‐Scale Exploding Wire Experiments of Blast Wave Propagation in Tunnels

ABSTRACT Underground storage of energetic materials in confined spaces, such as in mining operations, requires careful safety assessments to protect workers, equipment, and surrounding structures in the event of an accidental explosion. Understanding how blast waves propagate and attenuate through tunnels and intersections is critical for these assessments. Data for such scenarios can be obtained from both full‐scale and small‐scale tests. While full‐scale tests provide higher fidelity, small‐scale experiments are generally safer, less costly, less time consuming, and allow for more repetitions. When appropriate scaling techniques are applied, small‐scale tests can yield reliable results and help with trends and increased understanding of the shock dynamics event. In this work, exploding wires were employed as a controllable and repeatable energy source to investigate blast wave propagation in three representative geometries: a straight tunnel, a four‐way intersection, and a chamber connected to a tunnel. Side‐on overpressure measurements were collected alongside high‐speed schlieren photographs to capture shock evolution and reflections. The experiments demonstrated excellent repeatability, with standard deviations as low as 0.28 kPa, and revealed systematic effects of wall roughness and geometry on attenuation and shock front behaviors. Results scaled using Hopkinson–Cranz cube‐root scaling laws modified with an energy concentration factor to account for the confinement of the tunnels, showing agreement with some published high‐explosive data. These findings highlight the utility of exploding wire techniques for generating reliable confined‐blast datasets, supporting both hazard assessment and model validation for underground explosion safety.