Underground Inflatable Structures

I don't know the answer, but wouldn't that require a lot of air pressure to offset the weight of all that dirt trying to crush it?

Now if I had to work in those conditions, I'd have to go to a decompression chamber at the end of my shift, depending on how much pressure is needed it could require 10 to 14 days to decompress.

let me preach on it a minute. When you breath compressed air, the nitrogen in the air is compressed in you blood stream. So, as long as your breathing compressed air and remain in the compressed environment, the molecule of the nitrogen is small and will pass. But when you try to come to the surface to quickly, the molecule of nitrogen will expand in the blood and form a clot that will kill. Divers call this the bends.

So, even if someone has thought of it, I don't think it's practical.

Laby

vote for my answer

If this is something you are pursuing, just to give you an idea of some of the pressures you must offset. The overburden pressure is approximately 125 lb per square foot per foot of soil cover supported by a structure. (So 2 feet of soil cover, which is very shallow, would equate to a point load equivalent to a 250 man standing with both feet together for every square foot of top surface.) There are also the lateral earth pressures against the sidewalls to consider that will be dependant on depth, soils properties and contact slope. Additionally, there are water pressures to consider for possible overburden of perched/ponded water (seasonally saturated soils), snow load overburdens, landscaping overburdens, and uplift pressures from bouyancy during potential submergence. Finally, there are seismic forces to contend with.

However, I guess you could inflate a deep enough properly-designed double-lined structure with concrete in the outer liner and maybe water in the inner liner, and wait 28 days (Not sure how to get the reinforcing steel inside the liners). Though i do not think this is the intent, and there are easier ways to achieve the same end result.

Decompression shouldn't be an issue if you use a double skinned design and pressurise the gap between the skins rather than overpressurising the "living space" too much.

Yes the soil pressures can be high, but why not work with the geometries so that you can get the soil to be somehwat self supporting and then pick up the difference with the inflating structure. If you know the soil properties, then i'm sure that if you optimise a basic spherical shape so that you minimise the effect of the soil pressure. And with a clever use of an inflatable structure with reinforcing in clever positions (perhaps some thin carbon arches?) then this could work!!

Theres certainly some intersting stuff happening in inflatable structures.. Right now there is one circling us from above!! http://www.bigelowaerospace.com/ so i am sure that there is someone thta knows a thing or two about building them right!!...

Keep positive :) Greg

OK how about this all we are worried about is lateral pressure we would use concentric rings of polymers for the walls for the roof and floor we would use reinforced concrete and a steel lattice work to hold up the roof all we are concerned with is the lateral pressure from the earth around it. The inside would not be pressurized merely the rings them selves. Anybody have any ideas?

If your going to go through the expense and trouble to have reinforced concrete and steel lattice, why bother to inflate it?

Plus the reinforced concrete and soil overburden would have to bear on the concentric rings that support them, adding extra weight, thereby generating extra pressure in the rings. A solid roof and rings might work, but the material composing the rings would need to be extremely strong to offset the net pressure pushing on the inside of the ring. Plus this would probably be a specialty product allowing for short excursions, since the risk of a collapse is so dangerous it is unlikely that it could be permitted for much more.

No the concrete floor and roof would be supported by an internal steel structure the only thing the rings would be in place for is the lateral force of the earth around it

It hardly seems worth it, if you are going to put in all the columns to support a roof, plus ballast to offset bouyancy might need to be considered, a good seal to resist infiltration of water percolating through adjacent soils, design to resist seismic and soil liquifaction effects, and still have to maintain a slightly higher internal pressure or reinforce the inside of the inflatable structure.

Well the basic purpose behind it was to figure out a way to create a underground structure quickly. Obviously this method will be too much effort we will have to stick to good old steel reinforced concrete and a water proof sealant. But it was an idea we had batted around for awhile and thought we would throw it out there. Thanks for the input guys.

I don't think you should give up so quickly.

I picture a process of layering gunnite and steel mesh over the inflated form, to create a hard dome shell prior to backfill. Perhaps re-bar "arches" could be added at one stage, similar to an external frame tent.

This process would resemble, to some degree, the construction of concrete boats.

A kind of inflatable form. That could be useful, and since it would be a temporary construction structure, it would not require as much of a factors of safety as a permanent dwelling structure.

Support the inflatable off the pit floor and fill it with concrete to cover. Leave the inflatable intact on the inner surface of the concrete as your moisture bearer. Some type of adhesive on the inflatable to help it bond to the concrete.

Buy a Goodyear Blimp. Dig a hole to hold it. Fill it up with Nitrogen or something as useful for the project. Cover it with sprayed on concrete. Let set. Go in.

Otherwise, design space. Build inflatable. Put in place.

Dig holes in the ground that accomidate house trailers and put house trailers in them.

Account for water tables and provide sump pumps for the water and find ways to use the water.

Call the Morelocks.

Ask the mice.

What do you really want? A bomb shelter?

This is actually for building underground structure in locations where the weather is such that the work can only be done for a few weeks out of the year