Taking this idea on as a challenge was instinctual for Bowhill Engineering with physical development initiated almost immediately utilising a sliding collar arrangement never before developed. Prototype and testing revealed that there was potential for this system to work successfully in the horizontal plane on a CHS prop.
Engineering calculations and witnessed load testing/measurement completed the process with some slight tweaks and a setting procedure was formulated tested and documented. McConnell Dowell then verified our work through Aztec Analysis and production of the system onto all 50 units was rolled out.
This system was seamless and the safety and productivity gains for our client was significant with release of the units being as simple as the removal of a drain bung, once force was released the props sat safely in place until their removal with a crane! The alternative prop release process that was proposed was a clunky method of using a custom hydraulic jack to ease the weight from each prop to enable release, all of this between 5-12m in the air and close to the top of the tunnel’s recently installed concrete lid.
