Boulby mine shaft lining design—second restoration

Abstract

The linings of the shafts at Boulby mine, North Yorkshire, England, have failed twice. The two shafts, which have a finished diameter of 5.486 m, are 1150 m deep—the deepest in the United Kingdom—and pass through squeezing rock (Carnallitic Marl) at a depth of approximately 1100 m. Sinking of the shafts was carried out during the period 1968–74. Relining of both shafts through the marl zone took place during 1983–86, and they were again relined through the same zone during 1997–2001. The design of the new linings is detailed. Emphasis is given to the aspects that have been introduced to ensure compatibility with the predicted ground loading and deformation behaviour and which are considered to have been omitted in the previous two lining designs, leading to their early failure.