Page 46 - Built Expressions - Online Construction Magazine - November 2014 Issue

Cover Feature Backhoe Teeth cutters for cutting through soil to the Small Boring Unit for boring hard rock. Initially the ABM is set up in the starting pit on a predetermined length mclaughlinunderground.com or reinforced concrete block is installed of track. A backing plate, usually steel in the wall opposite of the boring to withstand the thrust exerted by the boring machine. The machine bores through the earth with a cutting head and the jacking force is provided by the hydraulic thrust. The pipe casing Auger Boring Machine and auger sections are added as the machine advances. Spoil is removed from the auger through the casing to a door located on the side of the machine. Gripper Tunnel Boring Machine (TBM) Main Beam of TBM is complex in its design, yet relatively simple in concept. The front of the TBM is a rotating cutter head that matches the diameter of the tunnel. The cutter head holds disc cutters (ranging from unnellingjournal.com positioned for optimal boring of the 11" to 20" in diameter) which are given rock type. As the cutter head turns, hydraulic propel cylinders push the cutters into the rock. The transfer of this high thrust through Double Shield Tunnel Boring Machine (TBM) the rolling disc cutters creates fractures in the rock causing chips The majority of ABMs are used to break away from the tunnel face. A unique floating gripper system to install pipe casing under • Microtunneling boring machine pushes on the sidewalls and is locked railroads, highways, airport • Slurry pressure balance tunnel in place while the propel cylinders boring machine runways, creeks or any area • Mixshield tunnel boring machine extend, allowing the main beam to advance the TBM. The machine of ground that cannot be open (TBM) Aker Wirth can be continuously steered while cut or disturbed in any way. gripper shoes push on the sidewalls Auger Boring Machine to react the machine's forward thrust. An Auger Boring Machine (ABM) is Buckets in the rotating cutter head used to bore horizontally through scoop up and deposit the muck on to Type of tunnelling equipment: soil or rock with a cutting head and a belt conveyor inside the main beam. • Auger boring machine auger. The majority of ABMs are used The muck is then transferred to the • Gripper tunnel boring machine to install pipe casing under railroads, rear of the machine for removal from • Double shield tunnel boring highways, airport runways, creeks or the tunnel. At the end of a stroke the machine any area of ground that cannot be open rear legs of the machine are lowered, • Single shield tunnel boring machine cut or disturbed in any way. There are the grippers and propel cylinders are • Earth pressure balance tunnel many types of cutting attachments retracted. The retraction of the propel boring machine for this machine. They range from cylinders repositions the gripper PG 46 Built Expressions Vol: 3 Issue: 11 November 2014