How to stop pole barn doors from freezing shut?

I keep my tractor in my pole barn. I have sliding doors on the pole barn. Normally they do not touch the bottom, but the area below the doors filled with some dirt and water and froze. Both doors were frozen in place. So when I went to get out my tractor to clear off the mess of snow we still have on the drive it was harder to get the door open than to clear the snow.

So, I'm thinking I'll dig out the area under the doors and fill it with gravel. This should allow the water and sediment that flows under the doors to go down through the rocks so that the doors should not freeze shut next winter. But then I got to wondering if there is a better way to fix this issue, other than concreting the whole area (the pole barn floor is covered with crush and run ...hard like concrete but you can see the dirt mixed in with it).

Any ideas?

Doc, I have a small trench lined with crushed rock under my door and it hasn't frozen.

Just about everything else has though!

The barn floor is crushed granite.

Jim

Now that sounds nice Jim. Instead of crushed I'm planning to go with the bigger 2 inch rocks. This will let the dirt and water drop on through. Seems like a simple enough fix ....now if things will just warm up a bit. Then I'll get a pickup load of stone and dig the ditch with the FEL. I'm going to go 10 ro 12 inches deep and a couple feet across. This is a low point so the extra should ensure it stays clear and the doors should never freeze to it.

Doc:
It sounded like you were writing the experience I had several weeks ago with my pole building. Went to get the tractor out and the metal sliding doors were froze shut. Only after pouring about 5 gallons of hot water down the side of the door did the ice underneath it give up its grip.
My pole building is all metal, sides, roof and doors. It had small sized crushed limestone on top of about 6 inches of fist sized crushed limestone. Would like it cemented but would cost many $$$$, so it will stay unpaved until I win the Lottery I suppose.
The area under the sliding doors (one on each end) gets filled up with dirt after driving trucks and tractors in and out when the tires are covered in mud. I try to keep them clear but dont want to big a gap-- too inviting for critters like skunks and ground hogs to come in and make it their home. Until I come up with a better solution, I'm going to get a good sized kerosene torpedo heater to heat the area inside when working and also thaw the doors so they will open when froze shut. (I have a man door so getting inside isn't a problem.) But, I might have to wait as everyone else in this neck of the woods had the same idea and there are none to be found in any of the stores.
Keifer, a RTV wannabe