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Constructive digger

Inserts frame as it digs down for safe construction even under building
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This small 1x1 meter digger slowly but surely removes the earth and rock layer beneath it, about 25 cm deep at a time, inserting a frame instead. Once completed, these frames can be replaced with a single external frame so that you can safely add a dug out parking space under the building or a basement to your house.
pashute, Aug 20 2020

For this reason? https://www.peterba...-house-in-finchley/
Dodgy builders digging basements without knowing what they're doing (often "backwards" out under the road...) [neutrinos_shadow, Aug 20 2020]

What Australia is really like... https://www.faceboo...4/3576636329024541/
[2 fries shy of a happy meal, Aug 21 2020]

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       Hope it's electric...   

       I'm almost certain I've seen a real world implementation of this. But I don't have poor sort of memory that only works backward, perhaps I'm remembering seeing it in the future.
kdf, Aug 20 2020
  

       Maybe someone's remembering it for you wholesale.   

       Do you dream of electric sheep at all, or unicorns ?   

       <Adjusts Voight-Kampff/>   

       "Describe in single words only the good things that come into your mind about... your mother. ... "
8th of 7, Aug 20 2020
  

       What should I expect from a dick, but a double-Dick reference... Have you ever read Scalzi's "The Android's Dream" ? The title is off course an homage but the book goes in a completely different direction on AI and genetic engineering. Oh, an interplanetary war and politics, too.   

       But back to the present... I may be mistaken about pashute's idea already being in use. I can't find anything like it, can you?
kdf, Aug 20 2020
  

       Nothing that small.   

       The technique of cutting a hole from below, and dropping a structure into it, is WKTE. It was used by the Brunels when they built the Thames Tunnel; a circular brick structure was built on the ground, and then intentionally undermined. Its own mass caused it to sink like a huge pastry cutter, and new rings of masonry were added to the top as it sank.   

       The problem with the system described in the idea is that the downforce on the "tube" being created will be relatively small unless mass is added at the top, which demands a much stronger structure. As the tube sinks, the friction with the surrounding strata increases, demanding more force.   

       How the segments would be removed without the tube collapsing inwards is not clear. Making the sections of pre-cast steel-reinforced concrete squares intended to remain in situ would make more sense.   

       The leading segments could have side panels that could be removed once the correct depth is reached, or they could simply be cut through with a cutting disc. They're not going to be expensive items individually, compared with the overall project cost.
8th of 7, Aug 20 2020
  

       I did think about tunnel-boring - but was sure I had also seen something similar for under-pinning a house foundation (as in pashute's example of retrofitting a basement).
kdf, Aug 20 2020
  

       It's actually more like installing main sewers than true tunneling; shaft-sinking for mining, or a well.   

       Underpinning is sometimes done by digging a series of small pits alongside the building and then cutting underneath and pouring concrete. After it's cured, a new series is interleaved and the process repeated. Eventually all the blocks join up and the underpinning is theoretically complete.   

       It can also be done by grout pumping, and wet substrates are often temporarily stabilized by freezing using arrays of pipes filled with suercooled circulating brine.   

       Presumably [pash]'s plan is to go down vertically, then excavate horizontally. All the spoil has to come out, and the materials go in, through a 1m2 hole ? Tricky for bigger projects.   

       A circular hole would be better than a square one - intrinsically more resistant to radial compression. And 1000mm precast concrete pipes are definitely Baked & WKTE, so part of the design's already done for you.   

       There are some certifiably insane humans in Australia who go looking for opals by narrow vertical shafting, but they're drilling into self-supporting rock- not soil- so no liner is normally needed.
8th of 7, Aug 20 2020
  

       //certifiably insane humans in Australia//   

       That's a long-winded way of saying "Australians".
bs0u0155, Aug 20 2020
  

       Not exactly.   

       "There are some certifiably insane humans* in Australia who go looking for opals ..."   

       While all "human"** Australians are certifiably insane, not all of them go looking for opals.   

       *for a given value of "human".   

       **observational evidence suggests that many of the non-human inhabitants (sharks, blue-ringed octupusses, sea snakes, crocodiles, western brown snakes, stonefish, funnel-web spiders, irukanji to name but a few) are, while not in the psychiatric sense "insane" do exhibit definite psychopathic traits; not only that but the flora and the geology show the same unfortunate tendencies ...   

       "Welcome to Australia ! We will now try to kill you ..."
8th of 7, Aug 20 2020
  

       I was under the impression that Austrailians have no worries, mate. I didn't know people kill there.   

       Last time I was there in 1998 I got on the bus preparing to pay on the way as typical in Israel. The people smiled and told us to leave our bags in the front. In the states they would be stolen immediately, in Israel a bomb squad would blow them up even before we would get to our seats. But here everyone was calm. We started our ride and I stood up. The driver stopped the bus on the side and asked what it was. I stated that I hadn't paid yet. No worries mate, when we reach the station. This in contrast to the Tshhh Tssss get in! I closing the doors Tshhh Tsss ouuuuuch Tshh Tss mrs get on I'm leaving. And he does. Or as they say since the Maccbia bridge disaster: Welcom to Eezrael end watch yoorr step.
pashute, Aug 20 2020
  

       The bipedal ape-descendants* are indeed welcoming and hospitable; it's the native wildlife, plant life and landscape that's out to get you. And trying to escape by sea doesn't help.   

       Big Red kangaroos can slash your abdomen open with a single well-aimed kick, and they can aim well. Cassowaries have a razor-sharp talon and are responsible for a number of unpleasant deaths, usually by exsanguination. Emus have sharp beaks and are basically just vicious. Cockatoos seem to have picked up the lifestyle choices of the original transported convicts, and become incorrigibe and accomplished thieves. Even the cute-looking Duck-Billed platypus has a poisonous spine on its rear feet ...   

         

       *Some are more "descended" ** than others...   

       ** "An Australian aristocrat is someone who can trace their ancestry all the way back to their father"
8th of 7, Aug 20 2020
  
      
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