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Abstract
Shaft lining systems that utilize bolted panels generally achieve their watertight performance by compressing a gasket material between the flanges of each successive panel. The materials used as gaskets for these systems have traditionally been lead or neoprene rubber. As with all gasketed systems, the watertight integrity of the system is reliant upon maintaining compression within the gasket material to overcome the hydrostatic forces of the water trying to push through the joint.
While these systems have shown themselves to be effective, there are numerous cases where systems have initially provided watertight performance, but begin leaking overtime. This loss of watertight performance is likely due to a loss of compression through the joint due to minor ground movements, thermal movements within the system of panels, vibrations or other sources of movement.
New systems are being developed that do not provide gaskets that rely solely on maintaining compression through the bolted seams in order to maintain their watertight performance. Instead, they provide sealing materials that fuse themselves together after the shaft liner is assembled. Therefore, after the system of panels is assembled, the seals between the two mating surfaces fuse together to become one continuous seal across the joint. The result is a seal that does not rely strictly upon the maintenance of compression through the joint in order to provide watertight performance. These seals have already demonstrated their performance at pressures up to 2,000 psi (13.8 MPa).
This paper will highlight some of the testing that has been performed to verify the effectiveness of these seals and summarize some of the future testing that has been planned for these innovative systems.
Current Waterproof Shaft Lining Technologies
Vertical shafts are the highways for most underground mining operations. All of the transportation of equipment, personnel and ore move through the shafts. If they don't operate properly, none of the important activities in the mine can take place. The lining systems that keep the shafts operating properly are generally asked to perform two critical functions; act as a structural form to resist the loads imparted upon it and, when required, perform as a waterproof barrier to hold back groundwater and keep the shaft dry.
Generally, the easiest and most reliable of these two demands to...