barring

Barring is timber installed in a mine shaft to support the roof, walls, or pillars during extraction work. It prevents collapse of the working space and protects miners and equipment below. The most common material is round or squared wood, typically softwood species chosen for strength-to-weight ratio and availability near the mine site. Barring works alongside other support methods, including stone packing and later, steel or concrete components.

A typical bar is 3 to 6 inches in diameter or width and ranges from 6 to 20 feet long, depending on shaft width and the stress load. Vertical bars, called props or posts, carry the main weight. Horizontal bars, called caps or collars, distribute load across multiple props and stabilize them against lateral shift. In deeper shafts with softer rock, miners install barring in layers or lattice patterns to spread stress evenly.

Failure and Maintenance

Barring deteriorates through crushing under load, rot from moisture and ground water, and sagging under uneven pressure. Crushed or rotten timber must be replaced before it fails suddenly. A collapsed bar section can trigger a chain failure in surrounding supports, trapping miners or burying equipment. Regular inspection during shaft work is essential; miners often tap bars with a hammer to detect soft spots by sound.

The term barring reflects its function: bars of wood that hold back the ground. It has been used in mining since shaft mining began, and the practice remains in use today even in modern operations, particularly in smaller mines, exploratory shafts, and underground development work. Contemporary mines also use barring as a temporary support while installing permanent concrete or steel frames.