Engineering Excellence into Large Diameter Drill and Blast Shaft Galloways for Safety and Productivity


Timothy Wakefield, Murray & Roberts Cementation

Final Galloway designs for vertical shaft sinking projects evolve from complex thought processes which integrate operational processes and systems and methods, of communication, power supply, drilling, blasting, ventilating, mucking, supporting, surveying, dewatering, sealing, concrete lining and shaft furnishing.  Attention to ergonomic design detail at the shaftsman / structure interface is at the heart of safe and successful multi-deck working platforms.  For economy the end product must have a low mass to reduce suspension rope end loads to be able to use smaller suspension hoists and have lighter headframe structures, be robust to withstand concussion damage, be easily constructible on site, be maintainable in the shaft barrel, and comply with safety and legislated standards. This paper’s ambition is to describe a systematic design framework and sequenced thought process that delivers a product that is engineered with excellence, illustrated by making use of the design that evolved during a recent Galloway project destined for a 10m diameter shaft. The Galloway engineering iterative process starts with laying out horizontal deck plans, mostly dictated by the permanent shaft purpose and configuration, whilst maximizing openings to enable muck to be removed rapidly for the best sinking cycles.  Concurrently the designer needs to understand the chosen sinking methodologies in conjunction with crewing to determine the number of decks and fix their spacing.  Insufficient access to move and line up formwork, set reinforcing rods and pour concrete in the confined spaces of the Galloway is inherently a major risk to be mitigated. An iterative and integrative process follows for the primary configuration which delves into increasing design detail, accommodating all other methodology influences, resulting in 3D layouts for further risk assessment, review and fine tuning by seasoned Shaftsmen.
Keywords: Shaft sinking, Galloway, Design, Safety