A rubble drain is also called a French drain, blind drain, rock drain, drain tile, perimeter drain, land drain or French ditch. They are constructed by digging a step-sided trench, filling the trench with loose stones, and covering the stones with earth.

RR is Random Rubble and DR is Dry Rubble

For a foundation for a building, it is necessary to excavate at least below the soil zone, and further, sufficiently to enable a strong enough concrete foundation to support the intended building.

Commonly, the base of the trench (the footing) will be a few times wider than the actual width of the foundation wall, so as to provide sufficient load bearing for the building.

Yes, a very strong tornado can sweep it off its foundation and reduce it to rubble.

For a foundation for a building, it is necessary to excavate at least below the soil zone, and further, sufficiently to enable a strong enough concrete foundation to support the intended building.

Commonly, the base of the trench (the footing) will be a few times wider than the actual width of the foundation wall, so as to provide sufficient load bearing for the building.