Our Projects.

• The Egress Shaft was a 12.4m by 4.2m (internal dimensions) rectangular shaft which extended 18m deep underground. The shaft’s external walls were constructed by a conventional bored pier and shotcrete wall retention system with the initial intent of a cast-in place structural concrete internal lining.
• Subterranean Solutions was engaged by RIA to test the parameters of using Structural Shotcrete in lieu of conventional cast in place concrete to help reduce the budget and construction programme by minimising the need for formwork.
• After vigorous assessment, the option for structural shotcrete was approved and the project awarded to Subterranean Solutions.
• The Shaft was excavated in 1.5m drops followed by a 150mm thick shotcrete lining to the bored piers. Once the shaft excavation reached the slab on ground level, the construction of the more robust and heavily reinforced structural shotcrete lining commenced back up to the surface level in 1.5m lifts.
• The Internal walls were 685mm thick but due to out of line piles the thickness reached up to 1500mm.

Subterranean Solution’s Scope of work included:

• Supply and place steel reinforcement to the shotcrete walls, slabs and dividing walls.
• Temporary works design of formwork, access scaffold and lighting and propping.
• Supply,  placement and all testing and quality management of all concrete poured and sprayed.
• Quality control and assurance. Despite the difficult access and several water ingress issues, the project was successfully delivered under budget and ahead of the program.