Dynamic Response Characteristics of Concrete Gravity Dam Induced by Underwater Explosion: Scaled Model Study

A scaled model of a concrete gravity dam was designed, and nine tests were conducted to investigate the dynamic response characteristics of the dam subjected to underwater explosions. The pressure time histories in the water, and the velocity and acceleration time histories of the dam during various explosions were recorded. The acceleration signal was processed by the Fast Fourier Transform (FFT) to perform time–frequency conversion. The energy migration law of the acceleration signal along the dam elevation was explored based on the theory of wavelet packets. Furthermore, the effects of charge weight, explosion distance, and explosion depth on the dynamic response of the dam were comprehensively investigated. The results show that the distribution of peak acceleration along the dam elevation closely relates to the explosion distance, but the global response of the dam tends to weaken as the explosion distance increases. Increasing the charge weight causes an enhancement in the dam response. Compared with an explosion suspended in water, the bottom explosion causes a weaker response to the dam. With the increase of the dam elevation, the energy of the acceleration signal gradually shifts from low frequency to high frequency. The bubble curtain has a significant mitigation effect against underwater explosions.