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D.J. Mac Cormick completes Townsville microtunnel

As part of the Water Security Infrastructure – Stage I Project for the Haughton Pipeline Duplication, the City of Townsville required a pipe installation comprising of 35.6 km of DN1800 GRP pipeline.

The pipeline alignment included microtunnelling under the Flinders Highway and between rail lines and rail corridors, requiring a 2.5 m outside diameter enveloper pipe to be installed 120 m in length by pipejacking.

To undertake the project, D.J. Mac Cormick Contractors selected one of its Herrenknecht tunnelling systems with a mixed cutting wheel, which was chosen as ground conditions ranged from stiff sand and clay to granodiorite rock.

Launch pit design. Image courtesy of DJ Mac Cormick Contractors.

A detailed temporary design was completed for the launch shaft shoring, thrust block, concrete pad, entrance wall and receival shaft for tunnel boring machine removal, while the chosen jacking system is capable of up to an 850 t safe jacking load.

The DN1800 GRP carrier pipe was installed inside the 2.1 m, 12.2 t jacking pipe – supplied by Humes – following the grouting of annulus outside of pipe.

Using trenchless construction, the pipe was installed in 11 days, with a total tunnelling drive length of 120 m.

For more information visit the D.J. Mac Cormick Contractors website.

This article was originally published on 31 March 2020.

If you have project news you would like featured in Trenchless Australasia contact Head of Production Chloe Jenkins at cjenkins@gs-press.com.au

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