What Does
Microtunnel Boring Machine Mean?
Microtunnel boring machines (MTBM) is used for installing gravity flow pipelines where tight line and grade tolerances are required. It utilizes a laser guidance system that transmits real time feedback like horizontal and vertical position, yaw, roll, and projected position to the operator. Steering jack helps the operator to steer the MTBM during drives. These machines can independently counterbalance earth and hydrostatic pressures. This method is used to install pipelines beneath rivers, estuaries, wetlands, railroads, harbors, runways, highways, etc.
Trenchlesspedia Explains Microtunnel Boring Machine
MTBM requires a jacking and reception shaft and usually has a maximum drive length of 1000 ft. Extended drive lengths are possible by using enhanced guided systems, additional slurry pumps, and by using intermediate jacking stations (IJS). The MTBM is introduced into the jacking shaft by hydraulic jacks and is mounted and aligned. The pipe or casing is inserted between the MTBM and the jacking frame. Power cables, and slurry lines are connected and the drive is allowed to advance. This process is repeated by inserting the next pipe between the jacking frame and the previously installed pipe till the MTBM reaches the reception shaft where the MTBM is retrieved. The slurry acts as a lubricant and also transports spoil out of the excavation pit. The MTBM is kept in the right line and grade based on the information transmitted by the guidance system to the operator.