mikrotunneling

Mikrotunneling is a trenchless construction method used to install pipelines with minimal surface disruption. It employs a remotely controlled microtunnel boring machine (MTBM) guided along a predefined line, typically by laser or inertial guidance, and launched from a retrieval shaft. As the MTBM advances, pipe segments are installed behind it to form the finished pipeline, while spoil is conveyed to the surface by a slurry system or pipe flush. The annulus between the pipe and the bore is stabilized with grout to prevent settlement and groundwater ingress.

This technique is commonly used for water mains, sewer lines, and other utilities in urban areas, as well as for crossings beneath rivers, highways, or railways where open-cut excavation is impractical. Diameters typically range from about 0.3 to 3 meters, with drives extending from tens to hundreds of meters, depending on soil conditions and project scope.

Key components include the MTBM, a guidance and control system (often laser-based), a hydraulic jacking or thrust system, a retrieval or launch shaft, and a slurry or flushing system to transport spoil and support the bore. Pipe segments are connected behind the machine and progressively advanced as the MTBM moves forward. After reaching the receiving shaft, the drive is completed, the system is dismantled, and the pipeline is tested and commissioned.

Advantages of mikrotunneling include reduced surface disruption, precise alignment, and suitability for complex urban landscapes. Limitations involve higher equipment and operational costs, strict ground condition requirements, and the need for careful monitoring to manage settlement and groundwater control. See also pipe jacking and horizontal directional drilling.