Statistical prediction method of inclined shaft blasting fragmentation based on dynamic damage distribution in excavated rock mass.

To address pilot shaft blockage and fragmentation control issues in inclined shaft blasting excavation, this study investigated the coupling mechanism between excavated rock mass damage distribution and fragmentation gradation using the Tianchi Pumped Storage Power Station water diversion tunnel inclined shaft project. A statistical correlation between dynamic damage distribution and blasting fragmentation was established through field blasting experiments and LS-DYNA numerical simulations. Based on this correlation, a fragmentation prediction model was developed using the dynamic damage distribution of the excavated rock mass.The study analyzed the influence mechanisms of three key parameters - decoupling coefficient, blasthole spacing, and detonating delay time - on rock fragmentation and size distribution, determining optimized blasting parameters for the project. Results show the damage distribution-based prediction model achieved high fitting accuracy (R²=0.9689) with maximum field validation deviation of only 2.49%, demonstrating excellent engineering applicability and promotional value. The decoupling coefficient and blasthole spacing are primary controlling factors for fragmentation distribution. Reducing the decoupling coefficient and decreasing blasthole spacing significantly enhance rock fragmentation degree and fine particle content while suppressing oversized fragment generation. Detonating delay time has limited impact, serving primarily an auxiliary optimization function. Optimized blasting parameters effectively reduced oversized fragment percentage and improved blasting efficiency and economic viability. The proposed blasting fragmentation statistical prediction method provides a novel and implementable technical approach for fragmentation prediction and parameter optimization in complex underground engineering projects.