There are a few impressive photographs of giant sinkholes that appeared in cities, such as this one:

Guatemalan sinkhole

However, followup information (e.g. Guatemalan sinkhole) or photographs on how these kind of sinkholes are filled up is hard to find. What approaches may be taken to "repair" or filling up these?

If dumping more earth or materials into them is ineffective due to underground-water, how can they be covered up properly without causing another collapse?

  • 4
    $\begingroup$ The earth has a lot of dirt (citation needed) ;) $\endgroup$
    – bendl
    Sep 26 '17 at 17:28
  • 3
    $\begingroup$ When I saw that picture, I thought "that must be photoshopped", but it appears real. Articles here and here. The second article in particular has some more detailed information/speculation about its formation. $\endgroup$
    – marcelm
    Sep 26 '17 at 21:28

How Japan Filled That Ginormous Sinkhole In Just One Week:
The Fukuoka sinkhole measuring 8,700 square feet (808 square meter), 65 foot (20 m) deep: they poured a mixture of soil, water, and cement into the hole—they use more than 7,100 cubic meters of the stuff in all. YouTube timelapse.

How To Fix a Giant Sinkhole about the two in Guatemala:
The first from 2007 one they filled with a soil cement made from cement, limestone, and water known locally as lodocreto ("mudcrete").

It's not clear whether cement is the best option, however. A 6,500-cubic-foot wad of concrete may serve to concentrate water runoff in other areas, leading to more sinkholes. Many engineers prefer the graded-filter technique, in which the hole is filled with a layer of boulders, then a layer of smaller rocks, and, finally, a layer of gravel. This fills the hole, more or less, while permitting water to drain through the area.

Whether this was actually done with the 2010 one I could not find (yet). Even the Wikipedia entry on the 2010 sinkhole (which you are also refering to) says This section needs to be updated.

It seems to be closed now, look at this video fragment compared with the bottom picture here.

Note that 7000-8000 m3 sounds like a lot, but that is only 400-500 truck loads.

BTW (I know, that is not answering the question, but it was too nice to not add):
Instead of filling them up you can also make a garden in them:

enter image description here
Photo credit: KnitSpirit/Flickr

  • $\begingroup$ Thank you Jan, it indeed seems that the graded-filter technique would provide a better water drainage, avoiding further collapses. I found that even in a simple post placement for supporting a tree-house gravel is similarly used. I guess the water will flow around a plug-like cement mixture, potentially causing collapses in the surrounding areas. $\endgroup$
    – Armfoot
    Sep 27 '17 at 19:09
  • $\begingroup$ @Armfoot water drainage isn't a stability issue at the scale of a post, aside from maybe protecting the wood from rotting. The gravel provides a little drainage at the very bottom of the post, but is mostly a shortcut for compacting and leveling the bottom of the hole; if you watch that video for just 30 more seconds, it shows them pull out a bag of cement and fill the rest of the hole with it, encasing the post in concrete. $\endgroup$
    – brichins
    Oct 12 '17 at 4:01
  • $\begingroup$ @brichins thanks for the explanation! It makes sense to use cement/concrete to stabilize the post, it fills up the empty spaces between the gravel too! In the sinkhole case it may not be the best alternative though. $\endgroup$
    – Armfoot
    Oct 12 '17 at 9:39

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