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Comment: Re:About rock bolts (Score 2, Informative) 379

by cellaboy (#15816038) Attached to: Big Dig - One of Engineering's Greatest Mistakes?
"Rock bolts are a staple in the mining industry. There are darn few failures. Of course the rock bolts are specified by engineers who work for the mining company and installed by miners whose safety depends on them. You tend to do things better if your life depends on it."

Spot on, at the coal mines I worked at in the UK these were used extensively and successfully. They were especially effective in situations such as "bad ground", for example, a 4 way junction with a couple of faults running through it. But in this situation there was wide understanding that this was not permanent, that in the end the fault(s) will win so the roof was inspected every shift.

For large headings and tunnels (mining & civil) I've seen grouting and rock bolts used (very impressively at Dinorwig power station in Wales), in civil projects interlocking concrete panels, I don't remember seeing panels and bolts used together but then I've been out of the industry for 20 years.

The time I spent with the NCB taught me how very impermanent underground excavations can be, but also how surprisingly resistant some others can be. A working pit is a constantly changing environment, exploit and move on. Structural permanence is relative to an areas usage, you don't want your main horizons and roadways to need constant maintenance, on the other hand the waste behind the coal face is in a constant state of controlled collapse.

Civil projects have a different focus, these are intended to be permanent structures, the engineering is different, the approach is different. I had the opportunity to apply to work on the Chunnel and also in South African coal mines. I refused both times for the same reason which was the overall safety record in these sectors.

BTW, some of the miners I worked with thought the epoxy was great, got them really high ...

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