Horizontal auger drilling
Relatively fast and efficient method in simple geological conditions. It is suitable for a wide range of profiles and lengths depending on the machinery. In domestic geological conditions they are usually not suitable for profiles smaller than DN 300 due to the frequent occurrence of grains that do not pass between the spindle of the auger and the wall of the extruded protector. Profiles around DN 1800 or lengths of around 60 m seem to be limiting. The method is not suitable, without a proper reserve in the profile, for sewers with a small gradient as the accuracy achieved is around 1% of the length of the sewer. This method achieves daily outputs of 6 – 30 m. Like controlled microtunnelling, it requires a retaining wall. It is important to know the location of underground lines, which should be verified by a sound if possible. During the actual implementation, dynamic shocks as well as static stresses are generated in front of the extruded protector and therefore it is not recommended to cross the networks in a proximity smaller than the profile of the extruded protector for cast iron or socket pipes, then two profiles (2D) are preferable. Disadvantages also include a relatively large starter pit of dimensions often greater than 2.5 x 7.0 m.
DN 350 – 1200 mm