Abstract: The drill-and-blast tunnel construction face various challenges, such as homogenization of machinery configuration schemes, insufficient consideration of surrounding rock grades, and impact of carbon emissions. To address these challenges, optimal machinery configuration schemes that take into account the construction period, cost, and carbon emissions under different surrounding rock grades are explored. Taking the left tunnel of the Wufu tunnel as the engineering background, based on the influence of surrounding rock grade on the selection of machinery configuration, the target surrounding rocks (grades of Ⅲ, Ⅳ, and Ⅴ) is divided into two categories : grades Ⅲ and Ⅳ－Ⅴ, and the reference table of machinery configuration in each construction stage is proposed. Then, a multiobjective optimization model with construction period, cost, and carbon emission as the core objectives is constructed, and an improved entropy weight method is innovatively adopted to establish a target preference weight evaluation system covering 12 secondary indicators such as initial investment, effective utilization rate, construction time, and carbon emission source, so as to quantify the preference of decision makers. Finally, the quantum particle swarm optimization algorithm is used to solve and optimize the machinery configuration scheme under different surrounding rock grades. The results show that: (1) The proposed method generates 81 and 243 optimal configuration schemes for grades Ⅲ and Ⅳ－Ⅴ surrounding rocks, respectively. (2) Compared with the original scheme, the optimized configuration of grade Ⅲ surrounding rock reduces the construction period, cost, and carbon emissions by 26.98%, 17.60%, and 19.06%, respectively. The optimal allocation of Ⅳ－Ⅴ surrounding rock reduces the construction period, cost, and carbon emissions by 27.53%, 21.11%, and 24.62% respectively.

Key words: drill-and-blast tunnel, machinery configuration and selection, carbon emission, surrounding rock grade, multi-objective optimization