Case Study: Assessing blast-induced air overpressure in tunnel excavation: a finite element analysis based approach

Blast-induced air over-pressure (AOP) is an unavoidable and potentially annoying problem that can lead to conflicts between mine management and living communities surrounding the blasting area. Controlling and monitoring AOP is crucial to mitigate its side effects. Various techniques have been employed to monitor the blast AOP. This study explores the use of the finite element method with the commercial software LS-DYNA to simulate blast-induced AOP in tunnel excavation. The numerical results were then compared to real field data to validate the model. The rock material and air were modelled using the MAT¬-MOHR-COULOMB and MAT-NULL keywords, respectively. The explosive was defined using the HIG-EXPLOSIVE-BURN model and Jones-Wilkins-Lee equation of state. Stemming material was represented by the MAT-SOIL-AND-FOAM material model. Based on the blast geometry and the average explosive charge per hole, the numerical modelling results were consistent with the field experiments. The maximum absolute error was 6.7 dB, with a percent error of less than 5% in two different models monitored at 100 m and 50 m distances. These findings indicate that blast-induced AOP can be estimated through numerical simulation as cost-effective and alternative to extensive field experiments.