부산대학교 도서관

A stemming construction for a borehole formed vertically or essentially vertically in the earth and extending through at least one seam of material from which earth is to be removed. It comprises: an inflatable body means comprising flexible portions for extending into contact with walls of the borehole and for transferring pressure from an inflating fluid introduced into the body means to the walls of the borehole, the inflatable body means being positioned in the borehole immediately below the seam of material; stemming material disposed in the borehole outwardly of the inflatable body means and contacting the body means. The pressure of the inflating fluid is adequate to provide an essentially vertical force component directed against the stemming material to support the material, the stemming material extending within the borehole a distance substantially equal to the depth of height of the seam of material; and, explosive material disposed in the borehole outwardly of the stemming material and contacting the stemming material, the explosive material being located substantially above the seam of material, the inflatable body means supporting the stemming material and the explosive material.