Question

contractor will use a package emulsion having a specific gravity of 1.25 and relative bulk strength of 130 to open an excavation in diabase rock, specific gravity 2.76. the drilling equipment available will drill a 4-in. blasthole. the explosive comes packaged in 3-in-diameter sticks. what is the recommended burden distance for the first trail shot? round the calculated burden distance to the nearest foot.

Answer 1

The burden distance is 7 ft

Solution:

As per the question:

Specific gravity of package emulsion,
`SG_(E) = 1.25`

Specific gravity of diabase rock,
`SG_(R) = 2.76`

Diameter of the packaged sticks, d = 3 in

Now,

To calculate the first trail shot burden distance, B:

`B = [(2SG_(E))/(SG_(R)) + 1.5]* d`

`B = [(2* 1.25)/(2.76) + 1.5]* 3 = 7.22`

B = 7 ft