Pipe jacking (Microtunneling)

In the wide world of pipe jacking techniques, GEOSA has devoted its main efforts to the construction of pipelines using pipe jacking/microtunneling methods. The company’s high standing and prestige in this field are widely acknowledged. Having achieved a prominent role in the Spanish market, GEOSA is currently expanding its activities to other countries.

This method consists essentially in digging a tunnel with a microtunneling machine and at the same time filling it with pipe sections (frequently made of reinforced concrete) which are fit together and pushed forward from the working shaft by hydraulic cylinders. The drive is transmitted all along the row of pipes to the tunneling machine, with enough force to overcome friction and allow the drilling head to break through the ground. As the pipe length increases, a new pipe section is fed to the thrust station. Rubble can be extracted through different means, depending on the type of tunneling machine used. The most common method is the aqueous route, which means draining the crushed rubble outside thanks to a stream of water generated by centrifugal pumps.
When the row of pipes exceeds a certain length and the friction forces grow, hydraulic pumping devices –called interjack stations– must be placed between pipes. Once the tunneling machine reaches the exit shaft, all essential parts of the devices can be recovered.
The procedure is quite versatile and adaptable to most soils –regardless of their hydrostatic pressure– in useful diameters ranging from 250 cm to 3500 cm, and allows for curved alignments both leveled and in elevation.

GEOSA has used this technique in the execution of jacking works with different purposes:

• Main sewers
• Water supply tunnels
• Service galeries
• Outfalls (desalination plants, wastewater, power plants)
• Drainage for linear works
• Highway and railway underpasses, etc.


Our company currently owns the following equipment:

  • 3 Full HERRENKNECHT AVN 1200 T machines, plus 1400 y 1500 extension kits (covering a diameter range of 1200-1400-1500).
  • 1 HERRENKNECHT AVN 1800 T machine, plus a 2000 extension kit (covering a diameter range between 1800 and 2000).
  • 1 HERRENKNECHT AVN600 microtunneling machine (shares some resources with the AVN1200)