| 摘要 |
PROBLEM TO BE SOLVED: To laterally blow out an object to be blasted by long hole blasting in a pilot tunnel of approximately 200 m in height, fall or lower it downward, by its own weight, to a horizontal gallery without clogging it, and convey it from the horizontal gallery to the outside for excavating a vertical shaft or an inclined shaft. SOLUTION: Inner long holes 4 are formed from an excavating surface 2 to the horizontal gallery 1 parallel with a centerline c at approximately equal distances from the centerline c around a pilot tunnel 3 along an upright or inclined centerline c extending from the horizontal gallery 1 toward the excavating surface 2. The volume of the pilot tunnel 3 is larger than that of the object to be blasted after the blasting by one long hole blasting over the generally entire length of one long hole 4. A center cut hole 5 is formed by sequentially performing long hole blasting. The long hole blasting by outer long holes 6 formed around the center cut hole 5 at generally equal distances from the centerline c is sequentially performed, and the blasted object is discharged from the horizontal gallery. COPYRIGHT: (C)2008,JPO&INPIT
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