山岳トンネル(3)

[VI-417] Outbreak Reduction Effects of Pre-Splitting to Add Guide Holes

〇Mitsuyoshi Tokunaga¹, Hikaru Iwasaki², Tetsuya Yokoyama³, Hajime Hamada⁴ (1.Okumura Corporation East Japan Branch Office, 2.Okumura Corporation Head Office, 3.Okumura Corporation Nagoya Branch, 4.Okumura Corporation Technical Research Institute)

Keywords:Mountain Tunnel, Controlled Blasting, Pre-Splitting, Guide Hole, Outbreak , Smoothing