Evaluation of blast mitigation effects of hollow cylindrical barriers based on water and foam

Using structurally weak materials to construct blast barriers is a promising approach for blast mitigation because these materials have multiple potential energy-dissipation modes and barely produce secondary hazards. This research experimentally and numerically investigated the blast mitigation effects of different hollow cylindrical barriers using water or/and polyurethane (PU) foam. In view of the characteristics that momentum acquired by the barrier debris might increase the near-field blast loading, a sliding impulse witness device was designed to determine the loadings induced by the air shock waves and debris impact. Six explosive experiments were performed to study the influences of the barrier's materials and structures in terms of pressure, impulse, structure response, etc. Numerical models corresponding to experiments were established, which can reproduce the dynamic response of the barriers. The experimental results show that among water or/and PU barriers, the protective performance of the PU_water barrier has advantages in comprehensive evaluation, whose mitigation efficiency for a scaled mass is 48% higher than that of the water barrier. The corresponding impulse is significantly lower because the foam is restrained by water, without premature disintegration to form a large debris impact. However, the pressure distribution of different barriers was not improved with the material arrangement, since that the main factor affecting it is the deflection of the blast wave through shadowing effect. The simulation results further revealed that although the dominant energy absorption mechanism and efficiency of the foam can be changed by material arrangement, the energy dissipated by the foam is negligible compared to the heat of explosion, resulting in a minimal effect on the overpressure distribution.