Main issues and solutions in intelligent hole-position design for tunnel blasting

Abstract

This study proposed an intelligent hole-position planning method for tunnel blasting to address challenges such as inconsistent hole layout rules and the lack of mathematical methods to coordinate uneven hole positions. This method considered the initiation sequence and rock-breaking direction. A hole layout rule is established based on the burden uniformity. The impact of several design factors on the hole-position distribution is explored. By using intelligent algorithms, the hole positions are adaptively adjusted in double faces to ensure even distribution. The hole-positions planning was implemented in a section of the Dabashan tunnel, which has a width of 12.2 m and a height of 8.7 m. The burdens are all 953 mm at the hole bottom and 801 mm at the charge-column top for the relief holes on both sides of the cut zone. The row spacing between contour-hole entrances is 67 % of the average row spacing between relief-hole entrances. The study shows that the design advance and cut angle significantly affect the average and standard deviation of row spacing between relief-hole entrances. Different zones require distinct design priorities for hole layout. The proposed hole layout scheme satisfies multiple objectives, including uniform burdens, non-excessive burdens, and minimizing the number of holes. This advancement promoted the development of underground blasting towards accuracy, greenness, and intelligence.