Explosion-Resistance Mechanism and Influencing Factors of Polyurea–Concrete Composite Structures

The dynamic response of polyurea–concrete composite structures varies under multiple factors such as polyurea spraying methods and explosion load conditions. Currently, research results in the field of polyurea explosion-resistant protection have not been uniformly conclusive, with conclusions often contradicting each other. Therefore, this paper expounds on the explosion-resistance mechanism of composite structures by integrating explosion stress wave propagation theory, summarizes the influencing factors through dimensional analysis, establishes a numerical model to determine the optimal polyurea spraying method, and quantitatively analyzes the relationship between influencing factors and the explosion-resistance response of the structures. The results show that, when the polyurea spraying thickness is the same, the explosion-resistance performance of concrete structures with double-sided polyurea spraying is optimal, followed by backside spraying, while frontside spraying exhibits the weakest performance; and, after determining the bonding strength between concrete and polyurea, the key influencing factors for the explosion resistance of polyurea–concrete composite structures include explosive charge, blast distance, and coating thickness. The maximum deformation under explosion load increases in a power function with the increase in explosive charge and decreases in a power function with the increase in blast distance and polyurea thickness.