One of DM Civil’s key trenchless technology capabilities are our slurry microtunnelling machines which are capable of installing pipes from DN150 up to DN1800 into soils up to 5MPa strength and rock up to 150MPa strength. These types of microtunnelling machines utilise the slurry shield system and can operate in dry or water charged ground conditions.
DM Civil has a current project to undertake an 80 meter microtunnelling bore under the Mitchell Freeway and Northern Transit Railway Lines. DM Civil proposed to utilise an Iseki TCS 900 Mixed Head microtunnelling Machine (MTM) with DN900 Reinforced Concrete Jacking Pipe (RCJP) to form a casing for the new DN700 Mild Steel Cement Lined (MSCL) bore collector pipe to be sleeved inside. The ground conditions of both sand and limestone required the use of a “Mixed Head” unit, which is Iseki’s “TCS” machine configuration.
In order to match the dimension of the DN900 RCJP, the MTM had to undergo some reconfiguration to enlarge the cutting head to match the outside diameter (O.D.) of the RCJP. This was not an easy task, because rock and mixed head machines usually cannot be easily altered to suit different O.D. pipes.
This is DM Civil’s largest Slurry Shield MTM to date with capability of bores up to approximately 1,200mm O.D. in mixed sand and hard rock up to 150 MPa in strength; i.e. 7 times harder than concrete. This machine can also crush rocks and boulders that enter the machine up to 200 MPa in strength; i.e. 10 time the hardness of concrete.
Our workshop and fabrication shop, in coordination with the Trenchless Division, also built a new control building to house the machine controls. Whilst the MTM was disassembled the workshop undertook some improvements to the MTM to ensure the machine reliability was up to DM Civil’s requirements.
DM Civil’s first became involved in trenchless technology over 35 years ago using auger boring machines (ABM) from America. Currently, DM Civil have a fleet of 4 different sized ABM’s capable of bores from DN300 to DN1600. These machines were complemented with the purchase of two guided boring machines (GBM), which accurately install pipes from DN150 to DN600.
We moved into Microtunnelling to augment and complement the capacity of our ABM’s & GBM’s with purchase Iseki and also Rockman MTM’s from Japan commencing in 2006. Over the last 13 years DM Civil’s Slurry Shield MTM fleet has grown and currently allows us to bore accurately in 9 different sizes from DN250 up to DN1200 in the complete range of boreable ground we encounter here in Western Australia, including wet ground and hard rock.
The secret to our success and growth in this business is having a fully trained and experienced trenchless technology division team, plus, importantly, a qualified, experienced and trained in-house workshop and fabrication shop team. They are able to deal with all manner of maintenance, repairs and modifications to these highly complex machines, which utilise combinations of hydraulic, electric, mechanical and laser control componentry.
Microtunnelling is a very cost effective methodology used for bores under roads, railway lines, services and structures, in wet or dry ground conditions, where line, level and grade are critical. Our range of trenchless solutions allows us to provide flexible alternatives and methodology combinations to install infrastructure varying from DN150 to DN1600 in any ground conditions.