posted 4 years ago
I have done this myself, on a small scale.
Taking a cue from posters who described putting posts in the ground, where the post were held in place with and sitting on top of jagged stone, I do the same in 5 gallon buckets.
Rather than sinking the buckets into the earth I drive metal posts along side or inside them.
No gravel is used.
The 4 supports along the front of my greenhouse use this kind of base, an they are as strong as I could want.
Buckets do need to be protected from sun damage, so I bank earth against them in the outsides.
I have consider up scaling this system in much the way you describe.
I would go with half barrels, each about 16" high, no gravel, and sitting in grade.
You can build up the soil around them for a dirt floor, use the top of the barrels to support floor beams, or some combination of the two.
Alternatively, we could enhance this system into a stacked barrel pillar.
Two stacked barrels tied together by embedding wooden posts or rebar in the stone that fills them.
Two stacked barrels would be roughly 66" tall, three would clear 8 feet.
Essentially this could be a "mechanical concrete" pillar.