Underground shaft development method

Abstract

An underground shaft development method comprises: (a) drilling blastholes extending into a rock formation, each drilled from a starting location defining a first blasthole end to an ending location defining a second blasthole end; (b) loading the blastholes with alternating layers of explosives charges and stemming material to provide multiple blasting decks across and within the formation, including at least a first blasting deck corresponding to the first blasthole ends and a final blasting deck corresponding to the second blasthole ends, wherein each blasting deck carries wireless blasting devices; and (c) detonating the explosive charges in a series of blasting stages based on blasting deck by initiating the wireless blasting devices in each blasting deck, proceeding consecutively from the first blasting deck to the final blasting deck, wherein after each blasting stage excavation takes place to progress the shaft in an intended direction.

1 . A method of sinking a shaft in a rock formation, comprising:
 during a selected shaft development interval:   (a) drilling blastholes extending into the formation, each blasthole drilled from a starting drilling location defining a first end of the blasthole to an ending drilling location defining a second end of the blasthole such that the blasthole has a depth between its first end and second end;   (b) loading the blastholes with alternating layers of explosives charges and stemming material to provide a series of blasting decks extending across and within the formation, including at least first blasting deck corresponding to the first ends of the blastholes and a final blasting deck corresponding to the second ends of the blastholes, wherein each blasting deck includes wireless blasting devices; and   (c) detonating the explosive charges in a series of blasting stages based on blasting deck by way of initiating the wireless blasting devices in each blasting deck, proceeding consecutively from the first blasting deck corresponding to the first ends of the blastholes to the final blasting deck corresponding to the second ends of the blastholes,   wherein after each blasting stage corresponding to the selected shaft development interval, excavation takes place to progress the shaft in an intended direction.   
     
     
         2 . The method of  claim 1 , wherein the series of blasting decks extending across and within the formation includes at least three blasting decks, including at least one blasting deck disposed between the first blasting deck and the final blasting deck. 
     
     
         3 . The method of  claim 1  or  2 , wherein in the selected shaft development interval, the depth of each blasthole is between 10-80 m. 
     
     
         4 . The method of  claim 1  or  2 , wherein in the selected shaft development interval, the depth of each blasthole is greater than 80 m. 
     
     
         5 . The method of any one of  claims 1 - 3 , wherein the final blasting deck is deeper within the earth than the first blasting deck. 
     
     
         6 . The method of any one of  claims 1 - 3 , wherein the final blasting deck is closer to the surface of the earth than the first blasting deck. 
     
     
         7 . The method of  claim 1  or  2 , wherein the shaft is developed to intersect an underground excavation. 
     
     
         8 . The method of  claim 1 , wherein in the selected shaft development interval, the wireless blasting devices in each blasting deck are programmed with a unique group identifier corresponding to the blasting deck. 
     
     
         9 . The method of  claim 1 , further comprising:
 during an additional shaft development interval following the selected shaft development interval, repeating steps (a) through (c), wherein after each blasting stage corresponding to the additional shaft development interval, excavation takes place to progress the shaft in an intended direction.   
     
     
         10 . The method of  claim 9 , wherein in the additional shaft development interval, the depth of each blasthole is between 10-80 m. 
     
     
         11 . The method of  claim 9 , wherein in the additional shaft development interval, the depth of each blasthole is greater than 80 m. 
     
     
         12 . The method of  claim 9 , wherein in the additional shaft development interval, the wireless blasting devices in each blasting deck are programmed with a unique group identifier corresponding to the blasting deck.