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Slurry shield microtunnelling around Oz

As part of the first privately-owned company to introduce slurry shield microtunnelling to Western Australia, the team at D.J. Mac Cormick Contractors have been at the forefront of microtunnelling and continue to offer a wide range of related services.

The company undertakes tunnelling projects Australia-wide and has offices in Western Australia, Queensland and New South Wales. D.J. Mac Cormick has a fleet of microtunnelling machines and systems for installing pipes from
150-3,000 mm diameter, using slurry shield microtunnelling methology and several types of slurry shield systems.

A brief history

Senior management and key personnel previously undertook major projects through Mary Donald Nominees as D.J. and M.B. Mac Cormick Civil Engineering, which was the first privately-owned company to introduce slurry shield microtunnelling to Western Australia back in 1995.

Company management and key tunnelling staff have skills and knowledge ranging from 15-25 years’ experience, and their expertise has been recognised through various project awards.

Awards won by the company include:

  • The International Trenchless No-Dig Award 2006 and the Victorian Case Earth Award of the same year for the Otway Gas Project, involving incline microtunnelling
  • Western Australia Case Earth Award 2005 for the Perth Main Sewer Stage 5 Replacement, involving installation of 1,500 mm sewer plastic-lined jacking pipes, launch, receival shafts and access chambers.

Key personnel have also had experience on international projects, undertaking microtunnelling in Kuwait from 2003-2006, with over 13,000 m installed at depths ranging from 6-20 m in high ground water table.

The fleet

The tunnelling systems are closed-face, earth pressure systems and tunnelling operations are undertaken at surface, with the tunnelling operator having both visual and radio communications with the pipe fitting crew in the launch shaft.

The tunnelling machine excavates material at the face of excavation and the jacking system is remotely controlled from the surface, with the tunnelling operator monitoring the excavation rate/cutting face pressure and jacking force.

Specialised jacking pipes with safe working loads that are flush-jointed to minimise friction on pipe in surrounding ground are installed behind the machine, one behind the other, until the machine reaches the receival shaft.

Launch and receival shafts are typically located at access chamber locations. Depending on the size of the machine utilised, drive lengths of 100-300 m can be undertaken. These are also dependent on the geotechnical conditions and the safe working load of the jacking pipes utilised.

The tunnelling systems are laser guided and steerable. Information is relayed back to the operation board and TV monitor at the surface, which ensures the machine has high accuracy and enables jacking forces to be monitored.

The company’s tunnelling machines are suitable for working in water-charged ground and a variety of ground conditions such as sand, clay, soft and hard rock. These machines are typically used for installing sewer or drainage pipe or installing casing/envelope pipe for pressure mains, water and gas.

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