Guided Boring System Designed for On-Grade Installations


Underground contractors now have a new option for the trenchless installation of water and sewer lines. The AXIS™ guided boring system from Vermeer is a pit-launched, laser-guided tool to install 25 cm to 35 cm pipe. The system can achieve pinpoint, on-grade accuracy and its versatile design allows for multiple applications in the installation of new water and sewer lines.

“We saw a void in the small-diameter, on-grade installation solutions currently serving the water and sewer market,” says Ed Savage, trenchless segment manager for Vermeer Corporation. “Some of the current trenchless methods are designed to achieve the extreme accuracy needed for this kind of work, however, they lack the productivity needed to compete with the open-cut method.”

The AXIS system is made up of four main components – the power unit, rack, vacuum pump and vacuum tank. The power unit contains the engine and hydraulic pumps and connects to the rack to power thrust and pull back of the drill stem.
The rack includes the thrust / pullback carriage assembly and gearbox. As the thrust/pullback carriage assembly moves up the rack, the gearbox simultaneously provides rotation to the cutter bit at the front of the drill head.

The drill head uses a flat-face cutter and when combined with the laser guidance system, the Axis system is capable of completing flatter grades more accurately. The drill head can also be retracted in mid-installation allowing the contractor to change the drill head and adapt to changing ground conditions.

Although the AXIS guided boring system method is intended to go straight, the operator can make slight steering adjustments. However, the system requires very little steering. Rather than steering to achieve line and grade, the system steers to maintain line and grade based on the original entrance pit set-up. When adjustments need to be made, the system steers via two pairs of hydraulically powered opposing rams on an “X” axis within the front of the drill head.

Drill stem segments, measuring 2 m long, are placed in the rack carriage. As rotation and thrust from the carriage assembly resumes, the drill stem is pushed through the hole. The process is repeated with numerous sections of drill stem until it reaches the exit pit. The AXIS guided boring system can complete bores up to 106,7 m in length.

Each segment of drill stem features a sight channel for the pipe laser and a hollow section that serves as the vacuum channel for the displaced soil. In the center of the drill stem is the connection for the drive shaft, which delivers rotation to the cutting bit on the drill head through the entire drill stem.

As the drill stem cuts its way through the soil, the displaced material is simultaneously removed by a high-power vacuum system. Spoil is then diverted to a vacuum storage tank. The vacuum process also provides for a cleaner worksite and allows a minimum annulus, which helps improve accuracy.

“A unique advantage of the AXIS system compared to other trenchless installation methods is its ability to either push or pull product pipe into place,” says Ed Savage. “This flexibility places fewer restrictions on the type of product pipe (steel, clay, HDPE or PVC) that can be used on a given project.”

Because of the flexibility of the four major components, various setup configurations can be used to adjust the machine’s footprint based on jobsite and transport characteristics. For instance, in an urban jobsite, the AXIS guided boring system can be set up in one lane of traffic for minimal disruption. The AXIS system has been tested in a wide variety of ground conditions ranging from clay and sand to shale and rock.

Source: Vermeer Corporation

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