stull
A framework of timber covered with boards to support rubbish or to protect miners from falling stones.
stull: a timber platform that props up ore and protects workers
A stull is a temporary wooden framework, typically made from timbers cross-braced and topped with boards or planks, built horizontally across the interior of a mine shaft or working. Its primary function is twofold: to support accumulated waste rock and ore fragments above it, and to shield miners working below from rockfalls. In hard rock mines, stulls are the standard method of managing broken ground and creating safe working levels when ore extraction leaves voids that must be filled or stabilized.
Stulls are classified by their construction and purpose. A waste stull supports backfill material (waste rock) and helps manage the geometry of extracted voids. A working stull provides a platform on which miners stand while breaking down ore from an exposed face above. The simplest stulls use round timbers laid perpendicular to the shaft walls and secured in notches or by friction; more robust versions employ squared beams with full wooden framing underneath. Board thickness and timber diameter vary with the weight they must bear, but 4 to 8 inch timbers and inch-thick planking are common in hard rock operations.
Stull construction and maintenance account for significant time and cost in underground mining. Timbers degrade from moisture, compression, and biological decay; inspection for rot, settlement, and splintering is essential before each use. Improperly seated stulls, uneven loading, or failure to replace weakened timbers can lead to collapse, crushing injuries, and loss of working space. In coal mining and some metal mines, stulls have been partly replaced by steel arch supports and concrete, which resist decay and deterioration better over long working periods.
The word stull is chiefly regional, used widely in British, Australian, and South African mining but less common in North American practice, where terms like timber set, breast board, or simply crib may be preferred. Its origin is uncertain, though it may derive from German or Dutch mining vocabulary. Stull remains the standard term in underground hard rock mining industries where timber is still the primary support material.