Comparative experiments on dynamic characteristics underwater induced by emulsion explosive and liquid carbon dioxide

Abstract

Liquid carbon dioxide (L-CO₂) fracturing is recognized as an eco-friendly rock excavation technique. However, the lack of experimental evidence has limited quantitative evaluation of its advantages on shock wave and vibration control. Therefore, comparative experiments were conducted with monitoring the shock wave overpressure and vibration velocity. The results demonstrate that: (1) the overpressure and vibration induced by L-CO₂ fracturing are significantly lower than those generated by emulsion explosive; (2) the L-CO₂ overpressure curve can be divided into four phases: exponential rise, oscillatory decay, negative pressure zone, and multiple bubble pulsations; (3) the L-CO₂ pulse exhibits lower peak overpressure, longer rise and decay times, and wider pulse width; (4) L-CO₂ fracturing produces a higher proportion of medium- and large-sized fragments, with energy predominantly distributed in low-frequency bands, leading to slower vibration attenuation, greater dynamic response factor, and smaller damping ratio in engineering structures; and (5) barrier holes mitigate vibration with a reduction of up to 7.26%, and phenomena such as concentration, diffraction, and barrier effects can be observed around these holes. The successful application of L-CO₂ fracturing technology in this reef removal project near buildings provides preliminary evidence supporting its feasibility and safety.