Herrenknecht AG is the only manufacturer worldwide who develops, produces and sells an entire range of mechanical tunnel boring machines. The high-tech products prove themselves in every geological and hydrological condition with drilling diameters between 0.10m and over 16.0m.

As market leader, Herrenknecht AG manufactures and sells Microtunnelling Systems with nominal widths ranging from DN 100 up to DN 4,200 for all outer diameters currently available on the market and pipe materials that can be used in every geological and hydrological condition. Herrenknecht AVN Microtunnelling Systems include all components for unmanned and manned Pipe Jacking.

These components are optimally adapted and allow safe and efficient tunnelling even below groundwater level without additional measures such as lowering of the groundwater level, pressurization or groundfreezing. The compact design makes these systems perfectly suited for the use in densely populated urban areas.


Diagram of the Microtunnelling Process

Microtunnelling is a special process for the underground and remote-controlled installation of pipes for sewage lines and pipelines with diameters ranging from DN 100 up to DN 4,200. Starting with a diameter of 1,200mm, the tunnel boring machines can be accessed, e.g. for cutter changing. From a launch shaft, pipes are jacked to an exit shaft by means of a jacking frame. At the same time, ground displacement or full-face excavation of the tunnel face is carried out with an unmanned, remote-controlled tunnel boring machine.

The ground is excavated by a hydraulically driven cutterhead. To reduce friction and to support the ground for a short time in order to avoid cavings at the cutterhead, a slurry medium is injected (in loose, uncohesive ground, bentonite liquid, comparable to a cement-water mixture; in binding or rocky ground water is sufficient).

The spoil is mucked out through conveyor screws and lines, running in the already jacked pipe, to a reception pit and from there to the surface. Here the soil and the slurry medium (bentonite) are separated. The slurry medium is then re-used.


Picture of a Micro TBM