MICROTUNNELING- Pilot Tube Method
Pilot Tube Microtunneling is a hybrid version of multiple trenchless methods. The three main components consist of installation of a pilot tube on line and grade and then install of steel casing by pipe-jacking and removal of spoils by auger excavation. This method is highly accurate in softer soils and lengths up to 400 linear feet.
Installation Considerations:
• Overhead Power Lines – Generally auger boring requires the use of an excavator in order to dig the pit and extract spoils from the pit.
• Soil Conditions – Ground conditions are a very important aspect when choosing a cutting head. In solid rock conditions for example, Aaron Enterprises would utilize a disk cutter head.
• Lubrication – Occasionally soil conditions require the use of a bentonite mud mixture in order to reduce the skin friction between the casing pipe and the material that surrounds it.
• Grade Control – This aspect becomes critical when tunneling around existing structures. Grade is also crucial when installing certain utilities such as gravity sewer systems. In these situations Aaron Enterprises would use a steering head that would allow us to maneuver both horizontally and vertically.
• Ground Water Conditions – After the excavation of a launching pit, crews often find themselves below the water table. A well point can be installed in order to control the influx of water.
• Visible Restraints of Setup Area – Different job site constraints may require special attention during mobilization and pit excavation. Restraints at the job location are an important consideration when using the auger boring method.
