Effects of Orifices on the Damage Characteristics of an Arch Dam Subjected to Underwater Contact Explosion.

Orifices designed into an arch dam for flood discharge significantly reduce the ability of the dam to resist an explosion, especially when an explosive charge is detonated close to an orifice, and the dam may suffer considerable damage in consequence. We created a fully coupled model to represent the dynamic interactions between reservoir water, explosive, arch dam and abutments. Shock wave propagation and damage initiation and propagation were compared between arch dams with and without orifices. The effects of orifices on damage modes and the spatial distribution of damage were investigated. Damage characteristics of the top and middle orifices subjected to explosive loads were also analyzed. Results showed that the top and middle orifices designed into an arch dam have an important effect on the impact resistance of arch dams, especially when an explosive is detonated at an orifice inlet. At a certain mass of explosive, complete failure of the dam wall at the adjacent sluice piers of the top orifices can occur, and penetration failure may also occur at the middle orifice. [ABSTRACT FROM AUTHOR]