Mining Geology, Mine Development and Surveying · Mine Development · 2 marks · Numerical answer
For the same 1200 kg charge per delay, PPV is 112.5 mm/s at 100 m and 20.3 mm/s at 300 m. Assume $PPV=K(D/\sqrt Q)^{-\beta}$. Find PPV at 200 m, to two decimals.
For fixed charge, PPV is proportional to D^(−β). Dividing the two observations gives 112.5/20.3 = 3^β, so β = ln(112.5/20.3)/ln 3 = 1.55822. At 200 m, PPV = 112.5×(200/100)^(−β) = 38.1907 mm/s, or 38.19 mm/s. The common charge cancels when determining the distance exponent.
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