Ludwig Pfeiffer

Microtunnelling is an efficient and environmentally friendly alternative to conventional pipeline construction using the cut-and-cover method that is used in challenging conditions.

It uses pipes with an outside diameter of up to about 4 m, which are driven from a launching shaft to a receiving shaft. At the bentonite-supported working face, the soil ahead is removed by a hydraulic or electric cutter head modified to suit the geological conditions. It is broken up further in the crushing chamber behind, before being pumped out of the tunnel to a separation plant using a bentonite suspension within a closed slurry circuit. Here, the soil is separated from the liquid, allowing the drilling suspension to be reused. Hydraulic cylinders push the pipeline forward out of the launching shaft. A laser-controlled system monitors the machine’s position and displays it in the control container. This allows driving of the advance into the receiving shaft with a minimal degree of tolerance.