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Center-cut method for tunnel excavation utilizing large unloaded blast holes and a circular pre-split
Center-cut method for tunnel excavation utilizing large unloaded blast holes and a circular pre-split
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机译:利用大型卸载爆破孔和圆形预裂孔进行隧道开挖的中心切割方法
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摘要
Disclosed herein is a center-cut blasting method for tunnel excavation. The center-cut blasting method includes the step of drilling a single central center-cut hole at the center of a center-cut region, drilling a plurality of auxiliary center-cut holes comprised of large unloaded auxiliary holes and loaded auxiliary holes that are alternately arranged around the central center-cut hole to be situated in a circle having a predetermined diameter, and drilling a plurality of spreader center-cut holes outside the auxiliary center-cut holes to be situated in concentric circles centered by the central center-cut hole. Thereafter, the center-cut holes are loaded with delay detonators and explosives and the center-cut holes are stemmed with stemming material at their entrances. The loaded auxiliary holes of the auxiliary center-cut holes are blasted so as to create a circular pre-split. After that, the central center-cut hole is blasted so as to create initial dual free surfaces. The spreader center-cut holes are sequentially blasted with a time delay so as to create final dual free surfaces.
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