| 摘要 |
<p>A blast hole liner comprised of a single length of waterproof, flattened, longitudinal tubing having an open upper end and a lower end portion terminating in a bottom edge folded about its midpoint with resulting edge halves joined together to define an upwardly open weight pocket. The liner is provided with a transverse seal above the pocket. The latter seal may be located closely adjacent a horizontal crease in the tubing formed by doubling the same back upon itself. In one embodiment, manufacture of the liner from a length of tubing requires no further cutting or slitting of the tube. In another embodiment, a second length of tubing, substantially congruent with the first-mentioned tubing length, may be provided to improve the strength and waterproof nature of the liner and to protect the innermost length of tubing from becoming torn or punctured. In the preferred embodiment, an inner length of tubing is disposed independently within the first tubing, such that the first tubing length alone is primarily subject to stresses incurred due to the weight pocket and filling of the inner tubing with explosive.</p> |
