Short answers, pulled from the story.
The United Kingdom made single shaft mines illegal in 1862 after a disaster occurred when a single shaft became blocked and trapped miners underground. This tragedy forced regulators to establish a rule requiring all underground mines to have a second means of egress.
Engineers choose lining materials such as mass concrete, shotcrete, fibrecrete, brick, cast iron tubing, or precast concrete segments depending on rock stability. In extreme cases involving halite, composite liners consisting of two or more different materials are required.
Shaft sinking contractors are concentrated in Canada, Germany, China and South Africa today. These nations host companies that specialize in deep mining projects across their respective regions.
Full-face shaft boring functions like a vertical tunnel boring machine to excavate shafts with greater mechanisation. As of 2019, the use of this method remains not widespread despite its promise.
Cheese weights keep tension on the steel wire rope called guide rope by hanging massive weights at the shaft bottom. These weights resemble a truckle or wheel of cheese due to their shape.