The Influence of Underwater Environment on the Effect of Underwater Drilling and Blasting for Bridge Pier Foundation

To investigate influence of underwater environment on the effect of underwater drilling and blasting, the action mechanism of underwater drilling and blasting was analyzed by taking the underwater blasting engineering of No.3 pier foundation of New Baishatuo Yangtze River Super-long Bridge in Chongqing, China as research object. Moreover, by using ANSYS/LS-DYNA finite element program, the processes of land drilling & blasting and underwater drilling & blasting were separately numerically simulated. Based on the which, the dynamic response characteristics of land and underwater drilling & blasting were compared by utilizing a blasting funnel test, characteristics of shock waves and inherent characteristics of aqueous medium. Therefore, the influence of underwater environment on drilling and blasting effect was acquired. The results showed that Mises equivalent stress near the water-bottom interface was lower than that of the same location subjected to land drilling and blasting due to the influence of hydraulic pressure from underwater environment. Under the same pressure, the volumes of underwater blasting-induced funnel pits were all lower than those of land blasting-induced funnel pits. With the same charge quantity, the deeper the water, the smaller the volume of blasting induced funnel pits. Compared with land drilling and blasting, the presence of underwater environment can accelerate the attenuation of explosion-induced shock waves to thus further weaken the effect of rock fragmentation in blasting. The research result can further enrich the underwater blasting theory system and provide practical guidance for the construction of underwater drilling and blasting projects.