Numerical study of tunnel blasting parameter optimization and vibration damage based on the RHT constitutive model

Abstract

To solve the optimization problem of blasting parameters and consider the influence of interaction between blastholes on the spatial distribution of surrounding rock damage, the Riedel-Hiermaier-Thoma constitutive model parameters of marble were first calibrated from numerical trial calculation and impact test. Then, the blasting excavation of a tunnel in full section was numerically simulated, and the evolution process of blasting damage of surrounding rocks under the interaction of multiple boreholes was investigated. Finally, the blasting parameters were optimized based on the three methods of initiation sequence, radial uncoupling coefficient and segmented interval charge, and the particle vibration and surrounding rock damage were further analyzed. The results show that the obtained constitutive parameters accurately describe the dynamic stress-strain response of the marble, and the simulated results can well reveal the evolution law of blasting damage. The rock damage develops outward from the blasthole center, and then the damage is connected and coalesced along the borehole connection line. Compared with the aforementioned other two methods, when the radial uncoupling coefficient k is less than 1.33, the blast damage of surrounding rock can be effectively reduced by changing the k value on the premise of ensuring the blasting effect. The average vibration velocity in the vertical direction of tunnel is greater than that in the horizontal direction, and the apex of arch and the middle of floor in this direction are more sensitive to blasting vibration. The research results in this study can provide reference for optimum selection of blasting parameters and accurate evaluation of surrounding rock damage in practical engineering.

Keywords

• marble
• tunnel blasting
• parameter optimization
• damage evolution
• numerical simulation