DIGGING METHOD OF A PRE-STRESSING NAIL TUNNEL BY USING A PRE-STRESSING EMPTY BALL, A HORIZONTAL OUTER HOLE, A HORIZONTAL MAGNIFYING HOLE, AND A HORIZONTAL BASE BALL

摘要

PURPOSE: A digging method of a pre-stressing nail tunnel is provided to reduce boring amount and to excavate inner gang pre-stressing and inner gang pre-stressing nail tunnel at once blasting.;CONSTITUTION: A digging method of a pre-stressing nail tunnel is composed like next. A pre-stressing nail is drilled on the face supposed to be drilled and a pre-support guide hole(30) at a pilot tunnel by additionally assembling a horizontal contour hole(40), a horizontal stopping hole(50), and a horizontal bottom hole. Those are blasted a pre-support empty hole, a horizontal outer hole, a horizontal magnifying hole, and a horizontal base ball.;COPYRIGHT KIPO 2011