Overpressure Comparison of Blasting in Air and Special-Made Hemispherical Structure

The explosive welding process always accompanies with explosive vibration, shock waves, overpressure, hazardous gases and noises. A method of designing a hemispherical structure with 36 m in diameter, whose entrance and smoke extraction opening are 8 m in height and 8 m in diameter respectively, is proposed to decrease the influence of overpressure during the explosive welding process. In order to evaluate the rationality and efficiency of the special-made hemispherical structure, the overpressure comparative experiments of blasting are carried out in air and in the special-made hemispherical structure with a 1/6 scale factor. The experimental results prove that the hemispherical structure with a 1/6 scale factor reduces the overpressure efficiently, especially for the propagation distance longer than 20 m. Furthermore, the overpressure along the tangent direction (perpendicular to the entrance of the hemispherical structure) is lowered more than that along the radial direction (the entrance of the hemispherical structure) for the same propagation distance. Considering the characteristics of propagation and reflection of shock waves, the possible reasons for the overpressure decreasing of blasting in the hemispherical structure are also discussed.