40d Talk:Cave-in

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Connectedness[edit]

Is this still valid? I recall that only truly disconnected areas cave in these days...

Yeah, this is what I've heard. I'm digging out a bunch of greater than 7x7 rooms now so we'll find out shortly. --Karlito 00:26, 30 October 2007 (EDT)

I've dug out some big rooms (10x10 I think is the biggest so far) and not had a cave-in for a season or so. I'm thinking it only does it on disconnects. makes it ALOT easier to plan your fort out. --BurnedToast 00:33, 30 October 2007 (EDT)
No kidding. What are the chances of accidentally completely disconnecting an area? I think that Toady One is going to continue to tweak the cave-in circumstances, though, so some things that don't cave in now may in later versions. --Peristarkawan 12:56, 30 October 2007 (EDT)
Sorry, but I don't understand what a disconnected area is. Could you try to explain? sinoth 12:50, 30 October 2007 (EDT)
A disconnected section doesn't connect to the rest of the map. As far as I know, that means it checks above, below, north, south, east, and west of a block of stone for connecting blocks, and continues checking through them to make sure the section isn't isolated. Toady mentioned something along the lines of it only checking for disconnects around the area you are mining. If the section is isolated, each block of the disconnected section will fall straight down. That's the general idea, I believe, and such disconnects are not easy to create. --Janus 13:12, 30 October 2007 (EDT)
I can easily see how to create an isolated support, but how would you create an isolated room? The dwarves would have to get there somehow... Also, wouldn't an isolated room (with nothing on any side of it, including above) be less likely to collapse because there's nothing nearby to collapse into it? --Bobson 13:49, 30 October 2007 (EDT)
1. Build a box with constructed walls from the ground.
2. Remove the construction connecting it to the ground.
Also, an isolated room, would have to collapse, unless we've got anti-gravity-field-generators. --Savok 14:59, 2 November 2007 (EDT)
I've mined out several levels underground. Then I dug channels (carefully) around the edge of the top layer. Once the last channel section was finished... bam! Cave-in. Only, it didn't stop at the first level below. It kept going to the last level dug out, taking with it all the loose debris. If there are any BUILDINGS in the region that collapsed, they will break apart. --AzureLightning 14:04, 30 October 2007 (EDT)

Use hidden comments for "editors eyes only" info[edit]

"Don't pay any attention to the information below this line! It is simply a placeholder!" - Why have it there if doesnt need to be? Take it away and re-add when something worthwhile is to be said. --Mizipzor 17:51, 31 October 2007 (EDT)

Large area collapses[edit]

When building my underground farms with light access I had a lot of collapses but once the room was finished they ceased. There 8 by 8 and three floors down with open air access. I think a collapse happens if you have a room greater the 7x7 horizontally and more than 3 vertically. From what I've observed it seems like it only checks for a collapse every time a square is dug. --Lucid 20:57, 31 October 2007 (EDT)

I dug an open pit in a sandy grassland region. The pit was 4x6 and one level below the surface. And yet, somehow I had a cave-in. It was minor, and only knocked my miner out for a few ticks, but I'm still trying to figure out why an open-air pit would register a cave-in. (In addition, nothing actually changed as far as the pit topography.) --RedKing 01:58, 4 November 2007 (EDT)

If you dig all the way around the edge then that causes a cave in, i.e if you make a C shape and then dig out the remaining wall the center will fall down. This will destroy any buildings underneath.Jikor

Avoiding[edit]

I removed the 7x7 info until someone can verify that it's relevant in the new version. I'd also be interested to know when rockslides or shearing happens. --Turgid Bolk 16:44, 13 November 2007 (EST)

I can confirm that the 7x7 thing ISN'T valid as of 39e. I've had a 10x20 room with two solid layers on top of it for years and it hasn't collapsed. Only three walls, too. --CrazyEyes 11:00, 06 August 2008 (PST)

On the safe collapse front, it might be worth noting that you can also take advantage of dust not passing diagonals to safely cause collapses without mechanics.--Kaypy 08:02, 11 July 2009 (UTC)

Cave-Ins In and ice...[edit]

Cave ins aren't supposed to damage the floor below? Is this still valid? I found an occasion where they do.

As sometimes happens, one pond froze over on my map. I dug down under the ice, and removed the support from under an island in the centre of the pond. I also dug a room (crypt) under the pond.

When the ice melted come spring, the 'ground' on the surface of the pond lasted a few seconds before realising it should collapse, and when it DID collapse it punched a hole into the room BELOW the pond. I know the hole was punched there becase next winter the ice froze down to the room below ONLY in the tils right below where the cave in occured, the rest staying distinctly wet.

Cave-ins and Ramps[edit]

I was under the impression that ramping the floor will dodge any cave in or isolation concerns that occur with channels, however, this is not the case, if a tile has water on it and is the last of adjacent tiles to be ramped there will be a cave-in. Is this due to water having weight and a feature or a bug? --Stalinbulldog 11:56, 9 September 2008 (EDT)

Cave-ins also happen if you remove ramps from a tile where there is a tree on the "downward ramp". Problem is, the tree / other item isn't visible from the "upward ramp" (even though it is the "same thing").Garrie 09:14, 11 July 2009 (UTC)

Confirmed[edit]

"Any item caught under falling natural terrain is encased in stone and must be dug out destroyed completely." I saw this has a "Verify" next to it. I have a video that confirmed it(started a hermit challenge). Here is the link ->http://mkv25.net/dfma/movie-1001#lastComment --0todd0 01:04, 23 December 2008 (EST)

I honestly don't see how this verifies the statement. --Edward 00:31, 24 December 2008 (EST)
I've verified that falling floor tiles will cause damage to whatever they hit but they don't destroy items. Falling walls will completely obliterate anything beneath them, with the exception of constructed walls which work like floor tiles. I've also noticed dust pushes items as well as units. Note that I'm using version 40d9. --Xonara 00:54, 24 January 2009 (EST)

Cave-in vs. objects[edit]

I'm pretty damn sure I've destroyed a unit of fire imp fat using a dropped (and constructed, no less) floor tile. 40d, too. --GreyMaria 19:21, 24 January 2009 (EST)

IIRC the movie above shows some bituminous coal surviving some falling floor. I tested it with some kind of yellow stone and a mechanism and it didn't seem to destroy anything, just pushed the stuff around. Are you sure it didn't get pushed off a cliff or into some magma or something? I don't know :/ --Xonara 04:32, 25 January 2009 (EST)
It was nowhere near magma or cliff. --GreyMaria 12:37, 31 January 2009 (EST)
I've dropped cave-ins on buildings several times (trade depot occupied by elves loaded up with cloth, suicide booth lever linked to a support holding up the ceiling above it), and occasionally I lost an item or two. Constructed floors are definitely capable of destroying objects, just not consistently. --Quietust 20:57, 4 November 2009 (UTC)

Cave-in vs. creatures[edit]

I have had many instances where my dwarf stands underneath a section of semi-support cave connected to the ceiling above him, and then survive mining out the supporting wall and have the ceiling fall on him. He was superdwarvenly tough, but this seems to contradict "Any creature caught under the falling material is crushed and killed." --FJH 13:24, 8 March 2009


Also, demons. At least SoF have [NOSTUN], so I'm curious if they will get stunned by cave-in-dust. Can someone test this? I don't have a demon chamber right now. MC Dirty 08:48, 24 March 2009 (UTC)

"Death. Since a cave-in kills most creatures instantly, it can provide a convenient or amusing way to off a group of creatures." That appears later on in the article. It seems safe to just go with the cave-ins kill *most* creatures caught under them. Shardok 00:58, 4 August 2009 (UTC)

In a test embark on top of a Goblin tower, I orchestrated a cave-in directly above the (friendly) Demon who was the civilization's Ruler. He was killed instantly. In other tests, I've even squished HFS demons by collapsing the ceiling of their chamber on top of them. I'd say it's probably safe to assume that cave-ins are instantly lethal to all creatures. --Quietust 20:59, 4 November 2009 (UTC)

Underground Forest[edit]

If you cause a cave in of a large tree populated area (7x10 in my case) the trees will remain intact once they drop a floor. I did not, however, play long enough to see if the trees regrow. Kenji 03 13:07, 18 July 2009 (UTC)

I caved in a very large area of 68x28 tiles. None of the trees survived the fall and no trees have regrown. The region did not have a high tree density but some should have survived. I also dropped another area (10x6) with the same results. Version 0.28.181.40d --71.145.167.39 04:35, 6 December 2009 (UTC)

Did you drop soil walls or just floors? --Quietust 06:09, 6 December 2009 (UTC)

After some anecdotal testing on two different maps, I've come to this conclusion (v. 28 181 40d16):

Soil type, zone humidity (temperate, ect...) something has an effect on the regrowth of mined out areas without discovering an underground river.

Map #1- Temperate, heavily forested. Top soil was sand/loam/limestone. Had tower cap and plant regrowth in exposed, unflooded irrigation channels. Map #2- Temperate, forested. Top soil is loam/rock salt. Zero regrowth in exposed, unflooded and flooded irrigation channels. Zero regrowth, or even survival of plant life beyond grass, when up to 6x6 areas of land were dropped 1 and 2 z-levels. No regrowth after flooding. No regrowth after covering areas with flooring tile.

'Conclusion: If you want to test to see if you can grow an underground forest without an underground river, channel into the top soil and watch for regrowth. If you get none, dropping top soil down z-levels will not help.'

Other than the area covered by floor tile, I gave all these tests over 4 years to regrow. Interestingly, grass/dirt patterns do shift over time. But you won't get plant growth.

It could just be that native Tower Caps will regrow anywhere, while other wood types require an underground river period. --Nenjin 22:12, 22 January 2010 (UTC)

Halting cave-ins[edit]

The article originally stated that only solid ground was sufficient to stop a cave-in from punching through the floor, suggesting that cave-ins would destroy constructed walls, though several tests indicate that constructed walls ARE sufficient to prevent a cave-in from punching through to a passage below (even if they were built over a channeled area with no floor), whether the cave-in consists of a constructed floors, constructed walls, or even natural stone, and they remain perfectly intact. --Quietust 19:20, 25 August 2009 (UTC)

Vacuum?[edit]

I've been setting up an obsidian farm that involves (in my plan) many cave-ins to work. So I've been intentionally causing cave-ins, and they seem to create a vacuum that sucks the miner in. Let me try to diagram it for you:

Key:
. - floor
_ - channel/open space
X - miner

Upper Level:
. . . . X . . .
. _ _ _ . _ _ .
. _ . . . . _ .
. _ . . . . _ .
. _ . . . . _ .
. _ _ _ _ _ _ .

Lower Level:
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .

Lower level post-cave-in:
. . . . . . . .
. . . X . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .

Come to think of it, the diagram is kinda useless, but I enjoyed making it, so w/e. Any ideas on this oddity? Is this official? --Waladil 15:26, 5 January 2010 (UTC)