Abstract: Taking the chamber blasting excavation in reef limestone strata as the research subject, this study conducted 7 groups of blasting model tests on reef limestone analog materials. By integrating Digital Image Correlation (DIC) analysis technology, the effects of different blasting methods, charge structures, and borehole layout patterns on the blasting damage characteristics of reef limestone were systematically investigated. The developmental characteristics of blast-induced cracks at various propagation stages under different influencing factors were revealed. Based on the blast contour formation control requirements and borehole spacing parameters obtained from the model tests, a full-scale geometric model was established to perform numerical simulations of chamber blasting excavation in reef limestone strata. The study analyzed the damage range induced by CD method blasting excavation in large-section tunnels and the particle vibration velocity at 30m distance. The research findings can provide technical references for the optimization of blasting methods and parameter selection in reef limestone stratum excavation engineering.

Key words: reef limestone, blasting, damage characteristics, excavation parameters