Experimental and numerical investigation on dynamic behavior of RC orifice targets subjected to underwater explosions

Abstract

Orifices are very common in hydraulic structures, and explosions may occur inside or outside these orifices. In the past, limited attention has been paid to orifice structures against underwater explosions. This study aims to investigate the blast resistance of orifice targets subjected to underwater explosions through field tests and numerical simulations. First, two orifice targets were fabricated and tested under the submerged explosions of emulsion explosives at the entrance of the orifices. The experimental data including explosion-induced pressure time histories in the water, structural deformation and damage were obtained. Afterwards, a numerical approach based on coupled Euler Lagrange was developed for modelling the blast behavior of orifice targets induced by underwater explosions. The applicability of the numerical method in describing the blast pressure, structural deformation and damage was verified using the effective test data. Using the validated numerical method, parametric studies were conducted to explore the effect of various parameters—explosive mass, detonation location, orifice plate, steel reinforcement, and concrete strength on the resistance of the orifice targets. The results showed that six wide cracks and a large number of micro cracks radiated from the center of the orifice. The deeper the detonation, the more energy is transferred to the target, resulting in more damage. The plate at the entrance can effectively mitigate the blast effect on the orifice target. Further, increasing the reinforcement ratio or using ultra-high performance concrete can lessen the deformation of the target and cause less structural damage.