Deformation failure and acoustic emission response characteristics of water-containing concrete under impact load

Concrete materials are widely used in construction projects. Many concrete structures are in an aqueous environment and subjected to impact loads. Under this condition, the mechanical properties and failure modes of concrete will change significantly. In this paper, the drop hammer impact failure experiment of water -containing concrete was established. The deformation and failure characteristics as well as acoustic emission response law of concrete under dynamic load with different immersion time were studied. The failure mechanism and acoustic emission response precursor characteristics of concrete under drop hammer impact were revealed. The results show that the peak impact force of concrete was exponentially related to the immersion time. Its failure cracks were mainly distributed on the diagonal of the impact surface and the central axis of the observation surface. Due to the dual effect of water on the dynamic mechanical properties of concrete, the cracks and damage degree of concrete increased first and then decreased with the increase of immersion time. The peak acoustic emission (AE) count was exponentially related to the immersion time. The acoustic emission "quiet period" could be used as one of the precursor characteristics of concrete instability and failure, and the "quiet period" gradually became shorter with the increase of immersion time. This research results are of great significance for evaluating the stability of concrete structures and warning of concrete impact damage.