Depending on the location, you may not want to dig down, you may want to build it up. Located on the base of a hill or in a low spot, water infiltrartion could be a problem. I wouldn't consider building codes, use your noggin and create your own cabin your own way. Love to see some pictures......

The location I have picked out is on top of a railroad grade. There are no tracks and the railroad was ended along time ago. I will make sure I take aot of pics to show you guys.

10 years ago, we built a fairly simple 12x20 log cabin. We put it up on concrete pylons that stick out of the ground about 2 ft. In doing some research, we were told that any closer to the ground and an animal might den up under there and cause problems. So far we haven't had any issues with that. Also, because it was built on pylons, the township considers it a portable building and taxes are much less than they would be on a permanent structure. This cabin isn't moving without some serious crane work, but I won't argue with the taxes. It's located in central Wisconsin and we went with a 9/12 pitch on the roof because of the snow. Haven't had any problems with that either.

Close but no cigar to you also. A floating slab is a slab with no foundation support. The structure can then be constructed on top of the Floating Slab. Depending on the size of the structure and the load reactions being transferred to the slab perimeter, A swail may be required, wich is a thickening of the slap at the load bearing points.
Maybe the terminology differs some from region to region but my discription came from my Code book in my office.

+1 bic

Up here they're called monoslabs or thickened edge slabs...really popular for places with good soils (gravel or well drained sands)but if you are in a cold climate, you need to insulate them properly and in alot of cases, the building has to be heated all the time...

I agree with Bic, same terminology here in Iowa. Another thing to think of is placing insulation under the concrete to hlep retain heat loss. I would also choose the rafters with a loft. I helped a buddy build one last year that was 20x20 for a house, and their is no space left. Granted this is his house, the couple hundred bucks for different rafters would have been worth it.

Relocated Badger what is a concrete pylon? A cement column?

Yep, Just another name for the same.
Thanks Guys for the supportive replys. I have been designing buildings and roof systems since 1985. This ain't my first rodeo. lol

So pour cement below the frost line and up a foot or so. The rest or bolt the bottoms of the logs to it?

On a 12x12 cabin , I wouldn't even worry about the frost line. I would level off my area. Spread 4" of gravel over the area. Cover the gravel base with 6 mil plastic. Build a perimeter form with 2x8's. Cut 2" high density foam sheathing on the gravel bed inside your 12 x 12 form. Pour your reinforced concrete slab keeping it even with the top of your 2x8 form. This will make the concrete approximately 6" thick. Before the concrete sets up. stick a couple 1/2"X 8"anchor bolts into the concrete about 4 ft from each corner. Leave the bolts stick up so you can anchor the bottom of youe walls to the slab. Enjoy building your cabin.
If frost raises the whole elevation of the cabin an inch higher in the winter than it is in the summer...Who cares. (As long as you don't have permanent indoor plumbing installed)

There won't be any plumming in it. I might be able to start building it in the next couple weeks. I have to bust up some concrete first to give me plenty of room. How long should the logs be for a 12X12 inside dimensions, an extra foot on each end.

If your building on top of an old railroad grade, how long has it been since it has been in use? If it has been used within the past 50 or 75 years I would guess it is a very thick raised layer of hard packed rock! You probably won't have a lot of issues with the ground shifting. I would also guess you will find it vry hard to dig down too deep!
Is this cabin going to be built out of logs or out of lumber? if it is built out of logs I would guess the weight would be distributed differently than if built out of 2x4 or 2x4 stud walls and sheeting!
Also Bic, would the pad you describe be the same as what some in my part of the world call a monolithic pad?

Out of logs, the only part that might be actual lumber is the floor.

Of course it is. It is all poured at the same time.

How long do you think the logs should be for a 12 foot inside wall? 15feet maybe?

Bic is a smart guy..i concur and re-affirm everything he has spewed from his doughnut hole..

depends on the diameter of the logs. I made mine 4 feet longer than inside dimensions. Milled them flat on top & bottom with a chainsaw mill, 7 inches thick, and scribed the notches.

that would be a 4/12 pitch and I'd say in a snow region that would not be sufficent pitch ......... I'd go at least a 7/12 and preferably a 9/12 which is roughly around a 37 or 37-1/2 degree angle

What the heck is a cinderbrick??? Is that a cinder block, or a brick???

its a cinder block.