Deformation of a Deep Shaft Inset in Coal Measures Rocks During and After Construction

SUMMARY Results obtained from vibrating wire strain gauges installed within the concrete lining of a 660m deep shaft inset are discussed with reference to measurements of carcass deformations made during the initial excavation. Prior to the placement of the permanent lining, roof lowering and floor heave occurred. The rate of movement, which has been shown to be localised in both roof and floor, decreased significantly prior to the installation of the roof lining. There are some indications that the floor heave was regenerated, slightly, through dinting before the completion of the lining. The vibrating wire strain gauge results support the view that the concrete lining is behaving in a manner similar to a series of fixed-ended, uniformly loaded beams, which are also being subjected to significant hoop strains. The stability of the lining is enhanced by the compressive nature of the hoop strains which neutralise the tensile bending strains where they occur.