| 摘要 |
A compressed air blasting device (1), insertable in a pre-prepared bore, has a cylindrical housing or tube (2) containing a number of air guns (4). Apertures (3) in the housing ( 2) direct the flow of compressed air exhausted by the air guns (4) so as to produce a build-up of pressure sufficient to weaken and displace material from the area surrounding the bore. The further enhance the effect of the device (1), the bore may be filled with water and sealed with a packer (11) mounted on the device (1) prior to blasting.
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