Application
Rock Boring is similar to auger boring in that Rock Boring utilizes a standard auger boring machine and augers for spoil removal. The difference is in the cutterhead attachment. Standard auger boring cutter heads are not equipped to cut through rock greater than 3,000 psi. Rock Disc cutter heads and Mixed Ground cutter heads manufactured by The Robbins Company provide Keefe with the capability to tackle the most challenging rock bores.
Casing/Pipe Material
- Steel Casing Pipe ranging in diameter from 24" O.D. to 72" O.D.
- Rock Boring is limited to smooth inside and outside wall steel pipe.
Drive Lengths
Ranging from 25 LF up to 500 LF and greater.
Soils
Rock Disc cutterheads are typically used for boring through hard, full-face rock (4,000 - 25,000 PSI). In the event that mixed ground containing cobbles and boulders is anticipate, an alternative, mixed ground cutter head equipped with a combination of disc cutters, carbide insert cutters, and carbide cutter bits can be installed on the same housing assembly.
Description
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The steel casing pipe is machine bored (augered) and jacked-in-place simultaneously, so that there is no 'open excavation' in front of the casing. The soils by auger conveyance within the casing.
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A cutting head suitable for the anticipate ground condition is welded to the lead casing. Keefe would typically utilize a Robbins Small Boring Unit (Model SBU-A) with either the Rock Disc or Mixed Ground cutterhead attachment. For larger diameter casings or longer drive lengths, Keefe would rely on the Robbins Motorized Small Boring Unit (Model SBU-M) with either the Rock Disc or Mixed Ground cutterhead attachment.
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Grade of the steel casing is continuously monitored by water level and adjusted through the use of a steering head fabricated to the lead piece of casing. Line is checked at regular intervals by conventional surveying instruments and manual adjustments can be made as necessary.