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A city on an alien desert needs to expand, here is the method I feel should be cost-effective and cheap.

Use the image below for reference. City expansion method

  1. A square area is mapped out and leveled off for the expansion.
  2. Small Trenches are dug to form a grid in the soil, dividing the expansion into even squares. The trenches are lined with concrete or another wall to prevent collapse.
  3. A flat disc with a large threaded hole is placed in each grid corner and intersection.
  4. Cables are laid in the trenches and wrapped around the disks in each corner. If you pull the cable from the edge, the disk rotates like a pulley, turning the threaded hole. All the pulleys are linked together.
  5. Each grid square has a ceiling tile laid on top of it. At the corners, the tile is cut away and the threaded hole below is exposed.
  6. In the threaded holes at each corner and intersection, Columns are installed. They have threads matching the disks. The columns are leveled and then guyed to the center of each ceiling square touching it. The columns are slightly taller than the planned ceiling height.
  7. When complete, a large ceiling made of symmetrical square tiles is laid on the ground, connected at each edge, and supported at the corner by a column.
  8. Finally, the four walls are built to box the ceiling in.

The cables are posted down to the ground at the edge. When the cables are pulled, the columns in that line rotate. The disk travels up the threads of the column, and the ceiling lifts.

This is done slowly, as breathable air is pumped into the gap between the ground and lifting ceiling.

In the end, all ceiling tiles are at the design height, supported by the columns at their corners and by guys at their centers. A new space is finished up by sealing the gaps, and is ready to move in.

I imagine expanding by several acres at a time this way, making large open spaces without lots of time out in the hostile air.

Does this construction method have a name and is it a sound idea?

Vogon Poet
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  • Or, you know, do without the finicky rotating disks and threaded columns, and just put fixed height columns and the ceiling tiles on top of them; then blast clean air to evacuate the noxious gases... (Or maybe I didn't understand what good the trenches and rotating nuts and cables and threaded columns are supposed to do.) – AlexP Feb 16 '22 at 01:33
  • Getting the tiles onto the columns one at a time will teeter them. Lifting the ceiling as a unit balances all forces. The cables turn the disks like threading a nut up the length of a bolt. Few people need to be working outside this way, guiding cranes, climbing poles and such. You turn all 16 nuts synchronously. – Vogon Poet Feb 16 '22 at 01:36
  • I would argue that it depends on that environment is it: reducing, oxidizing, many volatile compounds, low oxygen, low density, high density, high particulate count or something else? Depending on severity, there are PPE mitigations available. – Gault Drakkor Feb 16 '22 at 18:50
  • What are the special problems associated with building on a planet with poisonous air? Why does this building method solve those problems? Is it something to do with building the ceilings immediately on top of the floors and then "inflating" the buildings while pumping in safe air inside? In that case it seems to rely on the parts of the building moving relative to each other while being airtight. – Daron Feb 19 '22 at 13:20
  • Why not just build in the normal order? Dig a hole, lay foundations, build the framework for the floors and ceilings. Then finish the rest of the inside and outside as is convenient as regards transporting materials. I imagine there is an incentive to finish the outermost walls sooner to make them airtight, so you can build the inside without special gear. – Daron Feb 19 '22 at 13:26
  • The concept is to reduce worker exposure to the elements as much as possible, so I thought of a system like a huge "EZ-up tent" that can be erected by drawing cables in from a central point. – Vogon Poet Feb 19 '22 at 14:40

2 Answers2

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Requires major modification

There are a few problems here:

  1. No foundations. This is a very unstable structure, any movement of the ground is going to result in the building collapsing. Which may be fine if this is intended for very short-term use, in the same way that tents don't have foundations, but in the long term there will be problems.
  2. No airtight floor. Erosion and seepage around the base of the walls mean that the toxic atmosphere will get in, sooner or later, and a concrete base is easier to work on anyway.
  3. Unstable columns. Here's the first critical problem. The workers and their machinery need to drive over the relatively lightweight ceiling tiles to place major structural members - this risks damaging the tiles. Then they need to raise each column to the vertical and use guys to anchor it in place, with the anchors being the centre of each ceiling tile. The huge problems with this are that the ceiling tiles are not anchored to anything, and as soon as the ceiling tiles begin to raise then the guys slack off and the columns will start falling over. Even if the columns are held in place magically until the building is erected, there is no structural stability from any lateral forces.
  4. Cables in trenches around disks around columns. Simply, no. I cannot visualise a groove around the outside that does not involve the cable rubbing against itself and any slippage on a disk will result in uneven raising of different ceiling tiles and consequent buckling of the ceiling. Even if those issues could be overcome, as the disks rise the cable needs to be running progressively higher through the airtight outer wall on each side, with the cable length increasing as the disks rise (assuming the motor driving the cable is anchored to a point on the ground).
  5. Filling the building with air during roof-raising. Again, no. As per the previous point, the cables are violating the integrity of the outside walls while the friction resulting from trying to maintain a seal between the outer ceiling tiles and the wall would make the entire operation unnecessarily difficult. It might be possible to aim for overpressure, not worry about the seals during the roof-raising and run around sealing the gaps afterwards, but that is done much more easily after construction is finished, as noted by AlexP.
  6. Final shape. Assuming that everything else was possible, there is now a flat-roofed structure - bad for drainage, if there is any precipitation in this environment - which requires a lot of internal bracing for stability.

While I cannot prove a negative, I do not believe that this hypothetical construction technique has a name.

Apologies that this criticism is so harsh. However, for the purposes of building an enclosed city rather than a tent I suggest that supporting columns with solid foundations are critical and a sloping or domed roof is recommended. It may also be preferable to expand in hexagonal shapes rather than squares in order to increase the area enclosed relative to the amount of perimeter material required. If you really want the structure's roof raised from inside rather than using cranes from outside, consider using airbags as a technique rather than threaded disks - it's easier to control the rate of ascent of individual sections if problems develop.

KerrAvon2055
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  • It sounds like most problems such a 1, 4, and 5 can be fixed by deep-setting the columns in solid bases and using the cables (chains?) to rotate the whole column as a screw. The nuts remain stationary and climb the columns; cables stay in the ground. Walls can also be set deep into the ground for a barrier. Working on tiles remains an issue… suspended scaffolding maybe? Guys must maintain tension while the ceiling lifts: Maybe run through hollow columns? If whole structure could be raised from one safe draw point, that’s the goal. – Vogon Poet Feb 16 '22 at 02:19
  • Traditional Japanese architecture does not use foundations. Yet, some buildings managed to survive for centuries (check Nara or Kyoto historical buildings) despite earthquakes. – Otkin Feb 16 '22 at 16:55
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The solution suggested in question has many moving parts. Several moving parts are load bearing and are incorporated into the final building guaranteeing an expensive construction style. To place some of the key components worker exposure to the hostile environment seems likely.

Alternative: Prefab and heavy machinery

Have heavy machinery with enclosed cabs with good air supply. At and of shift they drive up to a dock where power can be supplied and a gantry similar to what is used for passenger loading of aircraft. Or driven into en enclosed garage for maintenance.

Prefab sections of foundation, wall roof are supplied via the garage. The prefabricated components would be built inside the existing buildings. The heavy machinery can then be used to assemble the building.

The expensive bit here is refilling the garage with air.

Alternative: Inflatable dome

Dome is inflated by umbilical, bottom is open and larger then building to be built. Workers can enter the dome by the umbilical. Workers would be able to move the dome into position. The dome would be designed to work similar to a hovercraft, that is it operates on an air bearing.

Once in place workers can then anchor it and partially seal the ground so pumped air volume can decrease. With a dome in place workers have a protected environments where the construction work can proceed in a method similar to earth construction. problem would be delivery of raw material.

Moving machinery, and materials to from site would be the most complicated and be more expensive then normal.

Gault Drakkor
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  • An enclosure is a novel idea, but size constraints for an inflatable dome covering several acres seem challenging. I don’t know what material could safely create such an enormous dome. One leak would ruin the entire project. – Vogon Poet Feb 16 '22 at 21:49