shaft raising

Shaft raising is a method for excavating vertical shafts, often used in mining and public works projects. This technique involves creating a shaft by working upwards from an existing tunnel or horizontal excavation. This approach simplifies the removal of excavated material, as debris can simply fall to the lower tunnel for collection.1

Historically, this was done using upward mining, but advancements like the raise climber and, more significantly, the raise borer, have revolutionized the process. The raise borer, developed in the 1960s, rotates a cutting head and pulls it upward through a pre-drilled pilot hole. This mechanized method drastically reduces construction time and cost compared to older techniques. Raise boring is efficient for shafts ranging from 3 to 8 feet in diameter and can achieve significant daily progress, even in hard rock. For larger shafts, reamers can be used in a downward direction, or the "glory-hole" method can be employed, where blasting creates a large opening enlarged by a raise borer.1