| 摘要 |
Horizontal entry tunnels are cut into or behind the rock face at selected distances and depths. From these entries cross-cut tunnels can be driven. Series of vertical under-reamed holes also can be driven down from terrain level to become part of the tunnel blast system. All cross-cut tunnels and vertical holes are loaded with explosives except for stemmed portions and exploded either simultaneously or delayed. The broken rock is thereby blown onto the pit floor and into the void created by the blasts to the complete elimination of the vertical rock face and with the production of a nearly even gentle slope of specified grade.
|
