Abstract: Problems exist in blasting excavation of Grade Ⅳ and Ⅴ surrounding rocks of single-track railway tunnel by conventional micro-bench method. Hence, the problems of conventional micro-bench method are summarized; the basic principles for bench size are proposed by investigation and theoretical analysis; a stable precise blasting design system for micro bench maintenance is established; a kind of W-shaped blasting network and a retractable lightweight operational platform with sliding device are developed; and a series of new excavation technology of one-time blasting of micro-bench with invert is obtained. The applicable results of the recommended technology to Youyi Tunnel on China-Laos Railway show that the new construction technology of micro-bench blasting excavation with invert can not only avoid the shortcomings of conventional one, but also greatly improve the standardized management level and project progress to realize normalized construction management.

Key words: single-track railway tunnel, new micro-bench method, bench excavation with invert, precise blasting, engineering equipment