I don't know if you can make the rock piles reset, but there's a great guide
here on how to use triggers and traps.
If it turns out rubble piles can be reset, you could put a wall switch up by the entrance and link it to every rubble pile to reset everything at once. Having fumbled my way through learning how to work with triggers, I'd say follow the guide above doing the step-by-step with the door and the torch in game to get a feel for where the options are and the workflow.
The biggest tip I can offer is once you use the option "Link Triggers: (trigger)" it will change the radial options on every other object which could be activated until a "Link to activated behaviour: (behaviour)" is set. Also, I never did figure out how to turn off the "Link Triggers" phase without linking an object (and then deleting the links to that object if I couldn't remember which trigger I was working with and where it came from).
It's a little tricky to explain, but imagine a switch starts yelling Marco! when the "Link Triggers" option is used. It keeps yelling Marco! until a "Link to Activated Behaviour" is chosen on a different object (yells Polo!). Where the confusing part could come in is if you've got a torch yelling Marco! but you change your mind and want the switch to do it instead - the game might not give you the menu option on the switch (link triggers) because it wants to hear Polo! first. An easy workaround is to have a throwaway object, like a door, you can make yell Polo! (link to activated behaviour) whenever that happens. Just delete the door once you've got everything else set up, and any stray unwanted links to it will disappear as well.
For the mine itself, assuming you can reset the rubble piles and you've placed a wall switch by the main door, it'd be relatively simple to set up. First, make sure every pile and switch has had the "Allow triggers and activated behaviours" option turned on (I think this option disappears once it has been activated, so if you lose track and don't see it on a rubble pile, that means it's probably already on). Then it's a case of ctrl+shift+left-clicking on the switch, choosing "Link Triggers: (activate switch)" then ctrl+shift+left-clicking on the rubble pile and choosing "Link to activated behaviours: (reset pile)". Do that switch trigger/rubble pile reset combination over and over again for every rubble pile on the lot. You should see arrows pointing from the switch to each pile when you hover over/click on the switch, which makes it easy to check if you've missed one. To make sure it works change to live mode (be sure to save your mine first
) and have a sim break a pile then activate the switch. If everything works, the rubble pile will be good as new.
In terms of metal under the rubble there might be an option in the rubble pile menu to set up the type of item(s) a sim could find. There's a chance the options might always have relics, nectar bottles, etc. If you don't want that there should be an option to turn off the chance of treasure from rubble piles. You could then use them as decor/for roleplay purposes, or you could design the mine so that each area could only be accessed after clearing a rock pile (just be careful if it's a community lot and you go this route - I don't know what would happen if your sim reset the piles and trapped wandering townies inside the mine). As for the spawners themselves, I don't think there's any way to adjust their spawn area, but I've never checked to see if they have any shift-click options.
The mine sounds like a really fun and clever idea. If you have any questions once you start working with triggers, feel free to ask. Hopefully the guide helps out, and you're able to create the mine of your dreams. And when it's done, I also hope to see it in the Swap Shop - I'd love to send some sims into it to seek their fortunes!!
