Page 373 - Rock Mechanics For Underground Mining

UNDERGROUND MINING METHODS

Figure 12.4 A hierarchy of under- for gas liberation, losses from the ventilation stream, and heat pick-up during air
ground mining methods and associ- circulation.
ated rock mass response to mining.

12.4 Underground mining methods

A comprehensive discussion of the general features of various underground mining
methods is beyond the scope of this text. Detailed accounts of modern underground
mining methods are given in the text by Hustrulid and Bullock (2001) with an intro-
duction and overview being given by Hamrin (2001). Attention is confined here to
the relations between working method, the rock mass conditions essential to sustain
the method, and the key orebody properties defining the scope for application of the
method.
The mining methods commonly employed in industrial practice are defined in
Figure 12.4. Other mining methods, mostly of historical or local significance, such
as top slicing or cascade stoping, could be readily incorporated in this categorisation.
The gradation of rock performance, ranging from complete support to induced failure
and granular flow, and in spatial energy change from near-field storage to far-field
dissipation, is consistent with the notions discussed earlier.

12.4.1 Room-and-pillar mining (Figure 12.1)
Ore is produced from rooms or entries, each of which serves the multiple rˆoles of
ore source, access opening, transport drift and airway. Pillars are generated as ore
remnants between entries, to control both the local performance of immediate roof
rock and the global response of the host rock medium. It is preferable to arrange pillars
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