Mining Geology, Mine Development and Surveying · Mine Development · 1 mark · Numerical answer
A VCR stope uses 165 mm diameter holes. Under the spherical-charge approximation of length at most six diameters, find maximum charge length in m to two decimals.
The criterion limits charge length to 6d. Convert d=165 mm=0.165 m, then Lmax=6×0.165=0.990 m. Thus 0.99 m. The result concerns the approximation’s geometry, not the full drilled-hole length.
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