SH20-1 Manukau Extension

Services: Soil Nailing

Main Contractor: Leighton-Works

Engineer: Golder Associates

To provide a direct link from SH1 for traffic heading to the airport and central and western suburbs as part of SH20. As part of the southern section of the Western Ring Route, it will increase capacity to help relieve congestion and support economic growth.

Grouting Services was awarded the subcontract to construct two soil nailed walls over a total of 750sq.m of excavated face. A total of 522No permanent soil nails where installed comprising galvanised RB25 bar installed in a 150mm drill hole with lengths ranging from 4m to 12m. Two full scale trial proving nails were also installed and tested to verify the designers assumptions made in relation to the geotechnical ultimate bond rupture. The shotcrete construction works included the supply and installation of the wall drainage, reinforcing and 30MPa shotcrete.

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