DM Civil has a guided boring machine (GBM) capable of direct installation of DN150 to DN600 pipes into dry soil conditions. This allows the DN100 pilot head to displace soil including sands and soft clay.
The GBM utilises a pilot steering head, which can be tracked by the operator using a theodolite in the boring pit. By viewing the LED lights in the head for line and level through hollow tube drill rods, the leading head can be steered with accuracy as the rods are inserted from the rear. The pilot steering head is attached to 1.0 metre long threaded hollow tube rods and the head is rotated for steering and pushed into position with the rods following behind. The steering head and pilot rods compress and displace the soil as the head progresses.
When all the rods are in position, 1.0 metre long segments of PVC product pipe with centralised steel auger tubes and flights inside, are attached to the threaded pilot rods with a cutting head. This is driven by the boring machine in the boring pit to produce spoil which is conveyed back along the auger tubes into the boring pit. The product pipe is jacked in behind the rods, which guides the cutting head and pipes.
When all the rods are in position, 1.0 metre long segments of steel auger tubes and flights inside, are attached to the threaded pilot rods with a cutting head. This is driven by the boring machine in the boring pit to produce spoil which is conveyed back along the auger tubes into the boring pit. The product pipe is jacked in behind the steel casings, which guides the cutting head and pipes.
As the product pipe is inserted, the pilot rods are removed as they emerge into the receival pit. After all the pilot rods are pushed out into the receival pit and the product pipe is jacked into position, the auger tubes and flights are pulled out revealing the finished main.
Bore lengths of up to approximately 100 metres can be achieved with an accuracy of +/- 20mm.
Photo: East Perth DN400 Water Main Replacement
At DM Civil, we can also utilise our Akkerman guided boring machine as a pilot for larger diameter auger boring using essentially the same technique. This methodology allows for longer, more accurate auger boring of steel casing to be undertaken. This technique is a very cost-effective methodology used for bores under roads, railway lines, services and structures, in dry ground conditions, where line, level and grade are critical.
DM Civil’s Trenchless Technology division can direct install DN150 to DN300 PVC pipe, to line level and grade, in sandy soils with Water Corporation approved slim-line spigot and socket joints, by either pilot auger boring or microtunnelling techniques.
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