Experimental investigation on protection measures of concrete gravity dams subjected to underwater explosion

Abstract

With increasingly tense international situations, the safety issues of dams under underwater explosion strikes have attracted attention because of their strategic importance. However, there is a lack of research on anti-explosion measures and technologies for dams, especially by means of experiments. Therefore, model experiments were designed to explore protection methods for concrete gravity dams subjected to underwater explosion. A 1:60 scale-down gravity dam with a height of 2 m and 13 dam sections was constructed, and the dynamic responses of the dam were monitored using various sensors. Initially, the influence of lowering the reservoir level is studied from the perspective of operation. Subsequently, the mitigation effects of the bubble curtain on the upstream face of the dam are investigated. Ultimately, the effects of an upstream protection layer constructed with hollow glass microsphere (HGM)-mixed concrete, asphalt concrete (AC), and ultra-high-performance concrete (UHPC) are compared. The results reveal that lowering the reservoir level is an effective protective measure for dams under underwater explosion. The upstream HGM-mixed concrete layer and the use of a bubble curtain have excellent mitigation effects due to the differences in impedance between air and concrete. The upstream AC layer upstream of the dam exhibits good energy-absorbing performance, which also decreases the velocity response of the dam. The effect of the UHPC layer on reducing response is general, but its high strength can be used for local protection. Based on the experimental results and their protective mechanisms, recommended protection methods for actual concrete gravity dams are proposed.