Design and construct delivery of the 6 storey deep retention wall system.

The project

A 30 storey residential tower in the heart of Brisbane with six levels of basement car parking. Works included design and install of 160linm of retention wall using 800mm diameter continuous flight augers (CFA), with wall toe levels up to 10m into the underlying low to medium strength rock.

The challenges

Tight verticality tolerances were necessary to ensure interlock of piles and a high degree of watertightness as well as avoiding intrusion of the piled wall into car spaces which was a further critical factor. Complex modelling of the wall behaviour, and its affect on the two immediately adjacent structures, was necessary to demonstrate adequate protection against potentially detrimental levels of movement and disturbance.

The solution

Traditional retention wall design software was supplemented with more complex methods (FEA via Plaxis) resulting in a combination of heavy gauge props to restrain the highly sensitive upper basement levels, with traditional anchors and walers below this.  Positional accuracy was guaranteed by the use of purpose built heavy duty augers. High capacity piling rigs ensured smooth and concise drilling of the ‘secant’ secondary piles and the medium strong rock.

Project Facts


Metro Property Development Pty Ltd

Main Contractor(s)

Brookfield Multiplex Constructions Pty Ltd

Keller Business Unit(s)




Download Project Sheet

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