>>2248982It's going to be detached from the main rock or show cracks. A shaft that is like an arch is unlikely to collapse but if there is a belly you should be careful around it as in
>>2247333 which is most probably safe if the rock is hard enough tho
>>2246798 The thing on the right is a hazard, that's why they chocked it >>2248814 The rock on the left for example might be a hazard, you can also see shards that are loose on the lower left and that whole shaft looks like a pain in the ass
A shaft that cuts through a fault is also dangerous because the rock around the fault is not solid.
If there's timber supports it means the miners didn't find it safe to be under the bare rock already and you should be extra careful when near them and look for unstable timber
Solid rock doesn't just collapse by itself unless there is some geological pressure on it and of course the harder the rock the less it is prone to collapsing
However clay does collapse without giving warnings and is very dangerous, some ore veins will have "sheets" of clay on their sides that can be some 10s of centimeters thick, these sheets can appear solid but they are just barely hanging on by virtue of the clay being sticky and can suddenly collapse under their own weight and many have died or been injured by this including myself, I've had a bucketful (2-3 tons) of galena ore mixed with clay fall on my head without having given any sign while I was drilling in the ceiling to fell the ore and I didn't like it
One of the main tools of the trade is a long prybar that is made from an old drill steel (we use 1.6 and 1.8m steels mostly) and the first thing we do before drilling is probe the rock around with such a tool for any loose rock. You get fined for not doing this
Sometimes you just can't avoid them rocks. Some time ago a guy who was working on a raise was coming down the ladder and a fist sized rock came loose somewhere upstairs and it chopped his index finger off as he was gripping the ladder
