Steerable auger

For larger bores, the use of a steerable auger is recommended. The auger drill tool has a slanted lead section, which houses a diode target. As with the pilot bore method, an optical passage through the auger sections allows the Theodolite CCD camera to monitor the deviation of the head from the intended bore axis.

At the end of the guided bore sequence, the product pipes, which have the same outer diameter as the casings - auger sections, will be pushed through. Larger product pipes may be used after the bore has been enlarged using a reamer tool for product pipes of a larger diameter. The product pipes will push the reamer unit ahead. The reamer tool has a direct drive connected via hydraulic hoses, back through the product pipes to the hydraulic power pack at the launch shaft.

When pushing the product piping through, the augers will be turned in a counter-clockwise direction. The soil removed during the reaming will then be conveyed to the target shaft where it would be collected and removed along with the casings - auger sections, which are ejected into the target shaft as the product pipes are added at the launch shaft.

Unguided drilling    Pilot rods    Dead end bore