Question updated based on the "on hold" vote...

Assuming we're on Earth (or something geologically and biologically comparable). Humans are at best in the middle ages, and there's no "magic" or advanced science.

Now the difference is, there is also a "Dwarf" species (presumably just some "Humans" that split off from the main branch a few thousand years ago). They don't like living on the surface, for whatever reason (could be as simple as "religion", for example). So they live underground, but presumably have shafts to the surface at regular distances (for fresh air, commerce with Humans, ...) Dwarves have a similar technological level to Humans, but are more advanced in dwarven skills like mining and forging...

So the question is: since Dwarves need to mine to "open up space" to allow their population to expand (and to gain resources, obviously), how do they get rid of all that stone? They would have so much of the stuff that it's basically a waste product. They have many options; they could drop it into "sinkholes" (if they happen to find one), or drag it to the surface and just dump it there, or use it to do commerce with the Humans, or build fortifications and infrastructure on the surface...

Which of those options would they favor best (and why), from a traditional fantasy dwarvish point-of-view? It should ideally take into consideration Dwarve's "values", and their strong technical and logistics abilities.

For example, Dwarves are traditionally "xenophobic"; they might deal with a few select Human traders that come to them, but they would probably not drive around in carts, selling their ware directly in the Human markets. OTOH, they probably would accept (large) orders from the local Human nobility, as refusing could make their life more difficult.

Assuming we're on Earth (or something geologically and biologically comparable). Humans are at best in the middle ages, and there's no "magic" or advanced science.

Now the difference is, there is also a "Dwarf" species (presumably just some "Humans" that split off from the main branch a few thousand years ago). They don't like living on the surface, for whatever reason (could be as simple as "religion", for example). So they live underground, but presumably have shafts to the surface at regular distances (for fresh air, commerce with Humans, ...) Dwarves have a similar technological level to Humans, but are more advanced in dwarven skills like mining and forging...

So the question is: since Dwarves need to mine to "open up space" to allow their population to expand (and to gain resources, obviously), how do they get rid of all that stone? They would have so much of the stuff that it's basically a waste product. They have many options; they could drop it into "sinkholes" (if they happen to find one), or drag it to the surface and just dump it there, or use it to do commerce with the Humans, or build fortifications and infrastructure on the surface...

Which of those options would they favor best (and why), from a traditional fantasy dwarvish point-of-view? It should ideally take into consideration Dwarve's "values", and their strong technical and logistics abilities.

For example, Dwarves are traditionally "xenophobic"; they might deal with a few select Human traders that come to them, but they would probably not drive around in carts, selling their ware directly in the Human markets. OTOH, they probably would accept (large) orders from the local Human nobility, as refusing could make their life more difficult.

Assuming we're on Earth (or something geologically and biologically comparable). Humans are at best in the middle ages, and there's no "magic" or advanced science.

Now the difference is, there is also a "dwarf" species (presumably just some "humans" that split off from the main branch a few thousand years ago). They don't like living on the surface, for whatever reason (could be as simple as "religion", for example). So they live underground, but presumably have shafts to the surface at regular distances (for fresh air, commerce with humans, ...)

So the question is: since they need to mine to "open up space" to allow their population to expand (and to gain resources, obviously), how do they get rid of all that stone? They would have so much of the stuff that it's basically a waste product.

I can see 3 obvious options. I'm wondering which one is the most likely/realistic, or if I missed some other, better option:

1. They could just dump it around the air shafts, and let the humans take whatever they want, if humans are around. The major issue here is I believe it would take quite a lot of work to get the stones all the way up to the surface. That is, the stone transport would be significantly more expensive than the mining itself. They would eventually grow "mountains" near the air-shafts. I can't judge how long it would take before that becomes a problem.

2. They could sell it to the humans. The amount produced would drive the price down, but they can still sell it for some profit, if the stones are "perfectly cut" to be directly usable as "castle building material". Therefore they would need to build near (large) human settlements, to have enough "buyers". The transportation problem is the same as above.

3. They need to find some natural "sinkholes" that are so large that they "never" fill up. I think those exist geologically, but I don't know how likely one is to find such a thing - in particular without access to modern technology to find them.

Alternatively (more realistically?), they might just prefer to settle at the location of large natural cave systems, where you get "space for free" and the mining is just enough to fill the caves with buildings. I don't know how frequent those cave systems are on Earth, but I would rather ignore that option.

Question updated based on the "on hold" vote...

Assuming we're on Earth (or something geologically and biologically comparable). Humans are at best in the middle ages, and there's no "magic" or advanced science.

Now the difference is, there is also a "Dwarf" species (presumably just some "Humans" that split off from the main branch a few thousand years ago). They don't like living on the surface, for whatever reason (could be as simple as "religion", for example). So they live underground, but presumably have shafts to the surface at regular distances (for fresh air, commerce with Humans, ...) Dwarves have a similar technological level to Humans, but are more advanced in dwarven skills like mining and forging...

So the question is: since Dwarves need to mine to "open up space" to allow their population to expand (and to gain resources, obviously), how do they get rid of all that stone? They would have so much of the stuff that it's basically a waste product. They have many options; they could drop it into "sinkholes" (if they happen to find one), or drag it to the surface and just dump it there, or use it to do commerce with the Humans, or build fortifications and infrastructure on the surface...

Which of those options would they favor best (and why), from a traditional fantasy dwarvish point-of-view? It should ideally take into consideration Dwarve's "values", and their strong technical and logistics abilities.

For example, Dwarves are traditionally "xenophobic"; they might deal with a few select Human traders that come to them, but they would probably not drive around in carts, selling their ware directly in the Human markets. OTOH, they probably would accept (large) orders from the local Human nobility, as refusing could make their life more difficult.