Spall Damage to Concrete Walls from Close-In Cased and Uncased ‘Explosions in Air

In recent years, industrial concerns for safety and protection against high-explosive loadings have increased. Industries that manufacture explosive devices or use processes with the potential for explosions use concrete barricades to protect workers from exposure to accidental blast and fragmentation. Other industries use concrete barricades as protection against terrorist attacks that might include blast or fragmentation. Reinforced concrete barricades can provide effective protection against high-explosive devices ; however, the high-intensity loadings from close-in explosions or fragment impact can create large magnitude, transient stress waves in concrete barricades that result in the generation of concrete spall on the back side of the barricade, even though the barricade itself does not suffer general failure. Concrete fragments generated by concrete spallation can be hazardous to personnel and equipment, depending on the size and velocity of the fragments. In this study, a numerical model was developed to predict spall damage to concrete walls from close-in explosions in air for cased and uncased munitions. The model was used to develop guidelines for designing concrete walls to prevent spallation.