Towards Rapid Prediction of TNT Blast-Induced Primary and Secondary Human Injuries in Urban Environments

• Developed predictive equations for rapid estimation of injury zones of various geometries (circular, elliptical, and astroid), enabling assessment of the effects and consequences of accidental or intentional explosions. • Characterized and distinguished primary and secondary blast-induced human injuries, quantifying their spatial distribution across diverse urban layouts in the Lisbon region. • The proposed equations provide a basis for potential applications in urban risk assessment, structural mitigation strategies, and emergency response planning for explosive events. • Performed GPU-accelerated CFD simulations of TNT blasts in complex urban environments to validate and support the predictive models. In densely built urban areas, explosive events produce blast waves that interact strongly with surrounding structures, resulting in amplified pressures and highly variable injury patterns. These complex interactions challenge conventional blast models and emphasize the need for improved, rapid injury estimation methods to support effective emergency response and mitigation. To address this need, the present study develops predictive equations for the rapid estimation of TNT blast-induced human injuries in urban environments, with particular emphasis on densely built areas characterized by complex street geometries. These equations were derived through regression analysis of an extensive dataset of simulated blast events with varying charge sizes, placed in three representative urban scenarios characterized by distinct street layouts and topographic conditions. The numerical simulations were performed using validated finite-volume Computational Fluid Dynamics models implemented in the GPU-accelerated commercial software Viper::Blast . The proposed equations allow the delineation of primary and secondary injury zones. Primary injuries are associated with overpressure effects on air-filled organs, while secondary injuries result from debris and projectiles and are directly correlated with predicted damage to masonry elements and glazing. Tertiary and quaternary injuries, which are respectively related to body displacement and impact, burns, inhalation hazards, and psychological effects, are not addressed in the present research. Results show that the urban fabric strongly influences both the extent and the shape of the injury zones. In contrast, terrain topography, provided that slopes remain relatively moderate, has only a minimal effect. Overall, the predictive equations offer a rapid yet reliable tool for quantifying blast-related injuries in urban environments. They support risk assessment, mitigation planning, and emergency response strategies for both accidental and deliberate explosions.