tunneling

Anyone have any good sources for how to build small tunnels?

I know they have been built for 100's of years in all types of sub-soil surfaces. I have never found a book or source that gives the ins and outs of safety, constuction, reinforcing, water table, other water issues, etc. I am pretty sure I could figure it out on my own. Would like to have something I can give to others that has already been proven.

Not looking to do the chunnel or big dig or anything large. something along the lines of an underground path from house to shed etc. say 7' x 4' should be plenty.

I'm interested in building some tunnels as well, combined with a root cellar and "hidey hole" for tornadoes.  Other questions you might consider is the total depth underground you want, how permanent you want it be, your area's seismic activity, and what kind of subsoil (or huge boulders) you have.

Around here, if a boulder can't be moved by a large back hoe, it is jackhammered into smaller pieces.  If it's too massive for jackhammering, then it's drilled and blasted with dynamite.  From my test holes, I've determined that my rocks can be handled by a back hoe, so I'm considering using one to dig a deep trench for the tunnel.  Then I'll form it up for pouring concrete.  I'm still debating on whether to use an arched ceiling, or a flat, poured concrete ceiling.  On top will be about 18 inches of subsoil and whatever topsoil I have left.  Then I'll attempt to grow grass.

A neighbor of mine built a seriously large bunker under his new house.  The walls and ceiling are two-feet-thick poured concrete.  For my tunnel, eight inches should suffice.  I do not plan to use any steel rebar because it rusts and actually breaks up concrete over time.  My concrete will be a stiff mixture containing rough aggregate.

If you need to burrow though a mountain (or hill), then my plan won't work for you.  I've heard of tunnelers using "Gunnite" concrete to line it, but it requires a special machine for spraying it on.  Tell me more about your terrain and the other considerations I mentioned at the beginning. 

Ted, thanks for the response and welcome to the forums. Where I live, I would be lucky to find a boulder I could not pick up with my left hand. the water table and rain is more of an issue. not to say i will always live here. It seems there is very little info on actually building a tunnel. Most of the info available is usually for huge tunnels. I have ideas on different methods that could be employed where I live and elsewhere. It is just mind boggling that I can visit old plantations and watch this old house, see someone escaped prison, robbed a bank etc and not easily find info on making them.

As I find info, will try to post it back here.

Ted A wrote:I'm still debating on whether to use an arched ceiling, or a flat, poured concrete ceiling...I do not plan to use any steel rebar because it rusts and actually breaks up concrete over time.  My concrete will be a stiff mixture containing rough aggregate.

I think not using re-bar tilts the scales toward using an arch.

A flat ceiling will be in tension, in some places. Rough aggregate will help resist shear, and compression is almost never a problem for masonry, but in tension, only long reinforcements will help much.

I've seen re-bar break up concrete, but as I understand it, this is mostly a problem when it is placed too close to the surface of the concrete. The interior is too alkaline to allow much corrosion of ferrous alloys.

My uncle had the coolest cellar that i ever saw.. I never saw the construction so it would take a bit of figuring...

Basically they old timers piled up  a dirt arch  (it was a dome for the cellar , but you should be able to copy it for your tunnel..)

OK you build the arch from dirt, then place rocks in the shape of the arch over the dirt. Pour cement to link all the dome rocks together,
After it dries then you dig out the dirt under the arch.. (lots of work by hand back in the old days.)

I don;t know if there was a footing under the rocks, but it would probably be a good idea.

I have been a small scale hard rock gold miner most of my life.
To give you a idea aboiut building a tunnel is hard not knowing the ground that you are dealing with.
If it is soft ground you will have to rock bolt it and gunite the walls after you put chain line fenceing up(lots of work) or you might be able to timber it? Or put a 8 foot culvert pipe in it But that is big money.
Look up old mining books on Google books and you might find something. Here is a good one

http://books.google.com/books?id=M_w4AAAAMAAJ&printsec=frontcover&dq=mine+tunnels&lr=&cd=21#v=onepage&q=&f=false

Ronie, I had an idea of using a trencher to dig the vertical walls and washing / drilling to do the other parts. I think it would be possible to us washing for the whole thing. Have also considered several other possibilities, including prefab ferrocement panels, compressing the soil in place, or even lifting the soil. The subsurface makeup dictates some of the decisions. If I had the right rock, i'd just need a pick axe.

I'm leaning towards the compression of the soil, as it could solve many problems at once. Have to work on a good method. I am sure I can come up with a few.

much of it may not matter as much on a small tunnel. be nice if i could wash out a 6 inch hole, fill it with something that has some kick and make it a 6' hole of compressed and bonded subsoil.

Going to read some books that Whitlock linked to.

Were i am we have a stable soil called Loess... it is a clay-ish soil that blew in and piled up after the last ice age... so you can dig a trench without the side supports.... some have even built underground structures by tunneling in the side of a hill of the loess soil.

Do you have to have the top covered with dirt? or how about an east west trench with a filon or glass side facing south? Kinda like a gable roof over the trench that could also be a green house to have winter greens.

Thanks, W 

The first thing I dig will be a pit greenhouse on the north side of the lot. a lot of trees are on the north side, along with a downward sloping hill to a creek/ditch. It would be nice to have a tunnel entrance into the greenhouse, but that should not be difficult given the location. There are several reasons I would like to be able to put in tunnels. Some dark, some light. Some reasons for tunnels: connect things while staying out of the elements. more constant temperature. easy way to run utilities. extra storage. out of sight, out of mind. It's like having a basement without a house above it.

I am digging a slot through the mountain top behind my shop to connect to another shop area toward my sawmill.  I will cover the top with a roof and about 6 inches of dirt to make it into a tunnel of sorts.

If you're looking for something with a little kick, there's plenty of solutions. Making explosives is quite simple, rather safe, and the directions are all over the internet. Most ingredients are easily attainable.

But, you're better off using a shovel and timber shuring for a small tunnel.


Explosives can only be used in a very rural situation, when you need a big hole fast.

just but a 7 foot culvert; already made for the job and tested for safety. prolly cost less then a pour and you dont need the guy with the degree. if you want a flat "floor" go with the ten foot and floor it with the appropriate wood.

We're thinking along these lines too. But our 'soil' is granite ledge that we'll be tunneling through. We've cut out a lot to create terraces on our mountain. Makes the land much more useful. The next step we want to try is heading straight into the mountain.

-Walter
in Vermont
Where the Field Are Rock

if you have that much rock you might consider looking into the old style hard rock mining standards. as i said above there are already products on the market that will make your job easier and faster. On the other hand you might also think about some of the brick tunnels and vaults built in the 1700 and 1800s. as i under stand many of them where used as bomb shelters of troop staging areas during various wars and you should have actual examples close to you.

We have a moderate sized power hammer drill, feathers and wedges. We also use ice. In the warm season we drill holes and then fill them with water in the fall. Over the course of the winter the ice expands and breaks the ledge so we can remove it the next year. Another trick we use is burning rock - especially good if the rock is stressed with the feathers and wedges. We removed over a million pounds of rock this way in one area.

Something else I've read about is "slow dynamite" which is a safer chemical reaction, safer since it goes so slowly. Faster than ice though. I've thought of dropping dry ice into the water holes but not tried that.

So far all of our projects have been cutting out ledge in an open manner, or splitting boulders. We haven't yet tried tunneling. We have a target spot we're studying.

Every time a big project like the new tunnel in Europe is completed we joke about getting their mole.

Ive done a bit of small work. using lead and a few days of tunneling. it seems to me that granite will be very stable if the tunnel is carefully done. and if you have the quarry close by i cant see any reason to not use granite shoring. my only real worry would be Radon.
Well i lie i dont like being underground and my worry is always of being the thin lubricant between rocks if the roof falls in.