According to Herrenknecht AG, the manufacturer of tunnelling machines from Schwanau-Allmannsweier in southern Baden, around 4,500 crossings are required for the current grid expansion projects in Germany – line sections where underground high-voltage cable routes have to be laid in order to avoid geographical obstacles. For trenchless installation, Herrenknecht offers various technologies for tunnelling, drilling and cable laying. In December, the company handed over an E-Power Pipe machine to Heitkamp Construction Swiss GmbH, which will use it in future on projects such as SuedLink.
Crossings run under rivers, swamps, agricultural land, transport routes or buildings, for example. Herrenknecht's E-Power technology is designed to enable cable ducts to be laid quickly and safely in the ground over distances of more than one kilometre without trenching. This technology allows both pressure-resistant and non-pressure-resistant pipes to be laid precisely – even at shallow depths - using horizontal directional drilling (HDD) and microtunnelling.
Fully remote-controlled tunnelling machine
The AVNS350XB is a fully remote-controlled, high-precision tunnelling machine with a drilling diameter of 505 mm, which is suitable for distances of more than 1,000 metres. It enables safe undercrossing of existing infrastructure such as pipelines, roads and waterways and allows drilling at very short distances of 1 to 2 metres so that several pipes can be laid simultaneously. Thanks to the jet pump and the integrated hydraulic unit, this machine can drill longer distances at higher speeds and cover distances up to ten times longer with smaller diameters than with traditional methods.
Two-phase pipe-laying process
The two-phase E-Power Pipe® process begins with the installation of a jacking unit that moves the jacking pipes and the machine along the route. The borehole is stabilised by the machine or the pipes. After the breakthrough at the target point, the machine is separated from the pipes and the prefabricated cable protection pipe is pulled back over the advance unit. The underground cables can then be pulled in.
Combining the advantages of microtunnelling and HDD
Herrenknecht emphasises that E-Power Pipe technology combines the advantages of microtunnelling and HDD, making it an efficient solution for grid expansion projects. Philipp Kohlschreiber, CEO of Heitkamp Construction Swiss, emphasises that E-Power Pipe enables precise and long drillings even under demanding conditions. Maximilian Bischoff, Product Manager at Herrenknecht, adds that the technology shows its strengths particularly in areas with long lengths of pipe and narrow corridors.
Heitkamp Construction Swiss is planning to use E-Power Pipe to lay cable ducts for the extra-high-voltage direct current line as part of the SuedLink project from April. The new subsidiary Heitkamp Energy Infra GmbH was founded in Germany for this purpose.
(Source: Herrenknecht AG)