Numerical simulation study of spallation in reinforced concrete plates subjected to blast loading

In the design of protective structures, concrete walls are often used to provide effective protection against blast from incidental events. With a reasonable configuration and proper reinforcement, the protective structure could sustain a specified level of blast without global failure. However, the concrete wall may generate spallation on the back side of the wall, posing threats to the personnel and equipment inside the structure. For this concern, it is important to establish appropriate concrete spallation criteria in the protective design. Earlier analytical studies have been based on simplified one-dimensional wave theory, which does not consider the complex three-dimensional stress conditions in the case of close-in explosion and the structural effects. This paper presents a numerical simulation study on the concrete spallation under various blast loading and structural conditions. A sophisticated concrete material model is employed, taking into account the strain rate effect. The erosion technique is adopted to model the spallation process. Based on the numerical results, the spallation criteria are established for different levels of spallation. Comparison of the analytical results with experimental data shows a favorable agreement. It is also shown that the structural effects can become significant for relatively large charge weight and longer distance scenarios.