Sensitive Blasting – A Worst Case Scenario – Nxburst Rock Breaking Cartridges
In any industry public relations can go a long way to helping you and in equal measure making your life difficult. No industry starts off on such a bad foot before anything is ever done more than blasting. As the consequences of a bad blast can be catastrophic and even lethal, the public are very quick to oppose and complain at the suggestion of blasting to be done anywhere near them.
The classic story goes something like this:
Complainant: Hello, I want to complain about the damage that today’s blasting has done to my house
Response: Sorry Sir, but there was no blasting today, blasting is scheduled for tomorrow
Complainant: Fine, I will call back tomorrow then.
Is there a better way to provide sensitive blasting services without the damaging risks associated with high explosives? Can you keep your vibration levels well below that 2 inches per second mark, or even below 1 inch? Our latest test may be of interest to you if you have ever done any blasting in a built-up area, near infrastructure or right in the middle of town?
In the middle of a quarry floor, with no relief in any direction, a 5’ x 5’ pattern was drilled with average depths of 8 feet. The 11 holes were set on 4 delays firing 3 holes on each of the first 3 delays and 2 on the last delay. To make it interesting, a steady light rain, water-filled boreholes and low ceiling made this blast about as close to a worst-case in-town blast simulation as we can get.
Vibration was measured adjacent to the shot starting at 20 feet away, and in multiples of 20 feet until 80 feet. Additional monitors were set up at 30 and 45 feet off the end of the shot with all monitors sandbagged on the bedrock being shot.
Adjacent to the Shot:
20’ – 0.77 inches per second / 42 HZ
40’ – 0.77 inches per second / 128 HZ
60’ – 0.32 inches per second / 73 HZ
80’ – 0.34 inches per second / 64 HZ
Off the End of the Shot:
30’ – 0.99 inches per second / 51 Hz
45’ – 0.87 inches per second / 102 HZ
With all measurements at under 1 inch per second you can see why Nxburst will be a valuable tool for even the most experienced blaster when dealing with sensitive structures and receptors.
no flyrock outside a 50-foot safe zone without any type of blast covering
Great article written by Spencer Shand at Coogar Sales & Services!