Dam safety |
Above: Figure 5: Installation of a sub-horizontal anchor adjacent to vertical anchors
to sacrificial frames and lowering them to the final positions. They shall then be fixed to the rock foundation with sacrificial footings, as shown in Figure 6. The sacrificial frames were also used to internally support the formwork, as access and the foundation profile made it difficult to use traditional externally supported formwork.
Once installed, the contractor assembles the formwork around the frames and pours the monoliths in stages. The biggest risk is the potential for tensile stresses and cracking to develop due to the hydration of the mass concrete and the foundation’s restraint. The design allows for additional reinforcement to counter tensile stresses from shrinkage and temperature effects. The monoliths’ concrete (S15) also has a minimised cement content to reduce
hydration heat and must be placed via kibble, which the cranes lower into its concrete placement position, as shown in Figure 7.
Collaboration key to success A key takeaway from the Murchison Dam upgrade
project has been the importance of establishing a collaboration framework and has led to Hydro Tasmania implementing this process in other projects. The Murchison Dam upgrades are progressing well and the team acknowledges the efforts of many to get the project to this stage. Once completed, the upgrades will significantly increase the flood handling capacity of the dam, mitigating the risks of extreme weather events. The project is scheduled for completion in December 2024.
Above: Figure 6: A sacrificial frame with the monolith reinforcement is lowered by crane to its final position
Right: Figure 7: Pouring a monolith with a kibble
24 | August 2024 |
www.waterpowermagazine.com
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