40d:Cave-in

A cave-in can occur if an area is detached from all supporting tiles. A room can be as large as you want to make it, as long as it is supported by at least one tile from below. The system is a bit buggy right now, since it is only a placeholder.^{v0.27.169.33a} Toady has stated he intends to implement more realistic cave-ins in future versions.

Cave-ins can be disabled through the init file, by changing [CAVEINS:YES] to [CAVEINS:NO].

How cave-ins work

Any unconnected section of rock (rock that is completely isolated from the rest of the world) will cave in. The game checks for rock connections along the X, Y, and Z axes (that's left/right, up/down, and high/low). Diagonal connections are not taken into account yet. Stairs count as supports for the rock.

Results of a cave-in

• Any creature caught under the falling material is crushed and killed.
• Any item caught under the falling material is encased in stone and must be dug out.
• Obviously, anything standing -on- the area that caves in falls and may be wounded.
• A large amount of dust is generated; Any creature caught by the dust from the collapse is knocked unconscious, and may recieve injuries
• All buildings and constructions under and above the falling area are destroyed
• Rock remains mostly intact, while wood constructions become logs
• Unmined rock and soil crashes through multiple floors, and stops only upon reaching solid ground, where it piles up
• Mined stairs and ramps will settle like unmined rock; Stairs down that fall onto previously empty floors will reveal the level below. If there's rock or floor above them, it'll cover the stairs.
• Anything falling into a flow (like water) sinks to the bottom^{v0.27.169.33a}

Avoiding cave-ins

Do not make unconnected sections of rock.

Actually, you're quite unlikely to cause cave-ins unless you are actively trying to cause them. In which case, you'd be wondering how to avoid cave-ins that cause damage to your folks. That's simple: Add a support under the stone mass, and link it to a distant lever. When you're done, hide everyone, pull the lever and watch the fireworks.

One of the more common accidental cave-ins results when you're taking out the floor in a checker-pattern and the area below isn't supported, resulting in a situation like the diagram below:

Floor -1
▒▒▒▒▒▒
▒    ▒
▒ X +▒ <-- The X is a floor tile. It's not attached, so it will fall down.
▒  +>▒
▒    ▒
▒▒▒▒▒▒

Floor -2
▒▒▒▒▒▒
▒....▒
▒...▒▒ <-- Causing this area to receive a cave-in flow and knocking out any dwarves in its reach.
▒...<▒
▒....▒
▒▒▒▒▒▒