Roof for underground house

I continue my fettish to find an inexpensive green way to make underground tunnels and utliity rooms.  I have land in the desert and would like to build a house into the side of a large hill and also put some of the utility functions underground, connected by tunnels.  Part of the reason is that I will be gone 3 or so months a year, and would feel more secure with things hidden (propane tank, water tanks, etc).  Part is that it gets hot in the summer and cold in the winter.  This would keep things below the frost level and keep me out of the extreme elements, as well as keeping animals from prowling about.  I am looking for a way to make roofs for the tunnels (need an interior width of 6ft), utility rooms (could be the same as tunnels but would prefer 8ft) and the roof for the house (will be 16-18ft).   I keep getting people that  tell me to use concrete and rebar...if that is the only answer, so be it.  I was just looking at some websites discussing CEB (concrete earth blocks).  I was wondering how feasible it would be to create a minimalist frame the desired width and cover it with concrete blocks that are arched to the proper shape, maybe 2" thick and 2ft x 2ft....lay it over the frame...add mortar...add another layer, making sure to offset it 4" or so...and add 4-5 layers of this.  I was thinking (hoping) something like soil cement would do the trick, possibly containing polyethylene fibers for as a different kind of rebar.  I plan on putting 4ft of soil on top of the roof.  Any comments?  I was thinking a good layer of something waterproof over the roof might be  good idea before the soil was added to cover it up, along with a french drain.  The frame?  maybe made of bamboo that had been arched (using steam?)...but I would like to stay away from materials that can burn. I occasionally see piles of used cattle panels for sale at a decent price...I have seen photos of sewers and subway tunnels from the late 1800's and early 1900's made with individual bricks using this construction technique.  I have the same idea, only my bricks will be greener and bigger.

I think you could use ferrocement in a similar way,  with less fuss.
Cattle panels are a great material  for ferrocement.

Mind you,  I wouldn't be willing  to put 4 feet of soil onto of anything I built myself,  too risky for me.

Looking forward to hearing ideas from lots of people. I'm trying to figure out something very similar,  and burying myself alive seems less than desirable.

I’ve been flirting with idea of using steel culvert construction to roof an underground space. They come in just about any size and configuration including giant pipes and pieces that are bolted together. Designs that can accommodate being buried and hold a lot of weight.

If you want to build arched spaces using blocks of material (no matter what material), thin wide blocks laid horizontally will not work as well as tall blocks. The strength of an arch comes from the blocks bearing on each other side to side down to the ground, and thin blocks will have little resistance to buckling out of shape if the load is not perfectly balanced. Layers of thin blocks will have the same problem.
Put two fat books together edge to edge, and try to bend the joint... pretty easy, right? Now put them together face to face... they won't bend without ridiculous effort.

Buried propane tanks are a normal thing, but I would NOT incorporate the tank inside any cellar/basement/tunnel construction (if codes would even allow it) since propane is heavier than air and could collect in such a space if there were a leak.

It would be easy to hide or obscure the tank access with a "fake rock" or plantings...

Kenneth Elwell wrote:Buried propane tanks are a normal thing, but I would NOT incorporate the tank inside any cellar/basement/tunnel construction (if codes would even allow it) since propane is heavier than air and could collect in such a space if there were a leak.

It would be easy to hide or obscure the tank access with a "fake rock" or plantings...

Thanks for the warning.  I was thinking it would be in an area completely by itself.  

James Whitelaw wrote:I’ve been flirting with idea of using steel culvert construction to roof an underground space. They come in just about any size and configuration including giant pipes and pieces that are bolted together. Designs that can accommodate being buried and hold a lot of weight.

 I also, but I don't know how to read technical manuals to tell me how thick the culvert should be.  There is a flanged culvert made that would be ideal.  It is half a circle and has flanges on it (flaps) that have holes already drilled in them.  The idea is that you can use a bottom and top half and bolt it together...I would want to use the holes to bolt it to a wall.  I just don't know what gauge to use for something like this.  

You've probably seen this place before(In the attachment) if you've looked into underground building.  My understanding is that he decided to do underground largely because he was away fairly often as well.  I talked with Bob Bobserson about a similar topic a few months ago here.  Hopefully you will find this useful.