According to Herrenknecht, AVN (automatic wet tunneling machine) or slurry machines with cone breakers are all-rounders for safe tunneling in the diameter range from 0.4 to approx. 4 meters. The microtunnelling specialists fully exploit their strengths, especially in dimensions that cannot be walked on. The liquid-supported excavation concept of the machines enables them to be used in all kinds of ground: from silt and clay to non-cohesive soil and gravel to rock. Depending on the diameter, both in pipe jacking and with segmental lining.
AVN machines are among the closed full-face machines with hydraulic conveying circuits. The in-situ soil is removed with a drill head adapted to the geological conditions. This means that the machines can be used in almost any subsoil. Standard or mixed soil drill heads are used in soft soils and mixed geologies. A rock drill head with cutting rollers is installed for driving in stable rock. A cone-shaped cone crusher in the excavation area crushes stones or other obstacles to the grain sizes that can be extracted parallel to the advance. The material then falls through sieve-like openings in front of the suction nozzle and is sucked off with the suspension via the conveying line. The drilling diameter can be flexibly increased by means of a double jacket and an adapted drilling head.
The shields and the cutterhead of this machine are completely custom-made but the final product has all the AVN 1600 properties.