Analysis of damage accumulating characteristics and vibration isolating effect of presplitting blasting in excavation of large-scale navigation lock

Controlling the blast-induced damage is of significance for the stability of division pier in the excavation of the large-scale navigation lock. Based on the on-site experiment, the peak particle velocities (PPV) induced by production boreholes were compared, and the damage evolution characteristics were analyzed with the help of the software LS-DYNA. Moreover, through the analysis of the on-site experiment results and numerical results, the blasting excavation scheme of the large-scale navigation lock was optimized. The research results indicate that the rock mass damage induced by production blast-holes will strength the pre-crack vibration isolating effect. With the increase of the width of the blast-induced damage zone, the vibration isolating effect is gradually increased, and finally stabilized at 50%. The attenuation rate of PPV increases with the width of blast-induced damage zone, and when the width of the damage zone reaches 4 cm, the attenuation rate gradually slows down. The damage cumulative characteristics induced by production and pre-splitting crack vibration isolation effect should be taken into consideration in the excavation of the large-scale navigation lock. Therefore, the optimizations of blasting excavation, including the cutting blasting and construction presplitting blasting, were put forward to reduce the blast-induced damage to reserved rock mass and optimize the blasting effect.