"As mines closed, many put very large bits of timber across shafts and backfilled them, thinking this would be safe.
Post-tensioned Pres-Lam mass timber lift shafts and stairwell core walls not only provide a strong and very stiff lateral load resisting system, but also damage limiting response in the case of a large seismic event.
Smoke detectors went off at 9 p.m. Thursday at the Soudan Underground Mine State Park in northern Minnesota, signaling what appears to be a fire in the timbers lining the shaft.
Her father retired as the chief executive of Edward Jacobs, a family-owned company in Johannesburg that produced timber to support mine shafts.
After the bodies were placed in the graves, the stone-walled burial chambers were roofed with timbers, and the shafts above were filled again.
Dating the waterlogged timbers of the shaft--7 meters of which were excavated this summer--and timbers that were dumped into it about the time of the town's destruction may help archaeologists pin down when the site was abandoned.
And dangerous: signs warn of rattlesnakes, and rough-hewn timbers prop up an inactive mine shaft.
A massive timber headgear was built over the downcast shaft and a twin-cylinder vertical winding engine, built by Robert Daglish of St Helens, installed in the engine house.
"In the process of sinking a shaft, you're destroying the timbers, you're destroying the frame of the ship, you're destroying the artifacts, and basically you're making a mess".
The tunnel entrances are on the outskirts of town, running under the sandy hinterland next to the border: steep narrow shafts shored with concrete or timber connecting to claustrophobic passages that lead to Egypt.
In the weeks leading up to the disaster, miners occasionally felt rumblings from within the mountain, while the pressure created by the shifting rock sometimes caused the timbers supporting the mine shafts to crack and splinter.
