Blasting-Induced Damage Mechanisms and Fragmentation of Concrete Frustums

Understanding the blasting effects and mechanisms of finite-sized concrete structures is crucial for optimizing demolition techniques and enhancing emergency rescue operations. This study investigates the blasting mechanisms and effects of concrete frustums under contact explosions through integrated experimental and numerical analyses. Focusing on detonation location variations across the frustum’s top surface, the research reveals a failure pattern: the upper half forms a shattered zone characterized by extensive fragmentation due to interactions between tensile wave reflections from top and side surfaces, blast-induced unloading waves, and secondary tensile wave impacts. Conversely, the lower part constitutes a fracture zone developing larger core and surrounding blocks primarily through tensile wave reflections from side and bottom surfaces, where side-reflected waves exert a dominant role. Critical findings demonstrate that detonation positioning significantly influences failure characteristics: central detonations (Point A) generate vertically propagating tensile waves that produce regular prismoid blocks and 58.6% more fragments than off-center detonations (Points B/C). In contrast, oblique tensile wave propagation from off-center detonations creates oblique prismoid blocks. Quantitative analysis reveals significant damage disparities with residual heights showing 26.4% (core) and 18.5% (side) reductions under 4.0 kg charges for central versus off-center detonations. The study further proposes a genetic algorithm–backpropagation neural network model achieving prediction errors controlled below 2.6% for damage characteristic parameters, establishing an efficient tool for blast effect prediction. These findings advance the fundamental understanding of finite-structure fragmentation dynamics and provide actionable guidelines for optimizing demolition strategies in disaster rescue scenarios requiring rapid clearance operations.