Small diameters and long drives
E-Power Pipe® – method innovation for protective pipe installation
All advantages at a glance:
– Fast, reliable and precise product pipe installation at shallow depths
– Use of all (including non-pressure resistant) product pipe materials possible, e.g. HDPE
– Safe embedding of the product pipe through controlled annulus backfilling
– Remote-controlled boring and product pipe insertion
– Borehole support at all times allows projects even in non-stable soils
– Excavation under groundwater possible
– No heavy equipment between launch and target pit
E-Power Pipe® in use
E-Power Pipe® is used for the trenchless installation of small diameter product pipes at shallow depths. Over long distances of more than one kilometer, both pressure-resistant and non-pressure-resistant product pipes are installed quickly, safely, reliably and precisely. The two-stage process integrates aspects of the proven Horizontal Directional Drilling (HDD) technology and pipe jacking (microtunnelling). Even with the most diverse project requirements, E-Power Pipe® offers the possibility of installing near-surface protective pipes and pipelines by machine – with extremely minimal interventions in the landscape.
The broad spectrum of applications ranges from the installation of cable protection pipes or underground cables for the expansion of the power grid to pipelines for gas supply, district heating or the transport of hydrogen.
Environmentally friendly alternative to the open-cut method
Minimal earthmoving, no heavy equipment between launch and target pits and thus no nuisance to local residents due to noise and exhaust emissions, continued use of agricultural land during construction, hardly any recultivation measures – E-Power Pipe® shows its advantages particularly where the concerns of landowners and environmental protection must be especially taken into account.
The machine can keep to the planned alignment with high precision while safely crossing under existing infrastructure such as pipelines, roads, railways or small bodies of water.
Two-stage installation process
A jacking frame is installed in the launch shaft. With its help, in the first step the special tunnel boring machine and the reusable steel jacking pipes developed for E-Power Pipe® are pushed through the ground along the specified alignment. After breakthrough at the target point, the TBM is separated from the jacking string.
In the target pit a pullhead is now attached to the jacking pipe string. The prefabricated product pipe lying ready for installation is connected to this. As the jacking pipes are pulled back by the jacking frame, the product pipe is successively pulled in. The borehole thus remains mechanically supported the whole time. During insertion, the product pipe is mechanically and thermally connected to the ground with the addition of backfill material.
Remote-controlled machine with powerful slurry pump
The AVNS350XB tunnel boring machine with an excavation diameter of 505 millimeters is the centerpiece of the E-Power Pipe® method. With this slurry-supported machine, drives are possible even in aqueous soils. The fully remote-controlled tunnel boring machine is equipped with a jet pump as the slurry pump as well as an integrated hydraulic power pack so drives of more than 1,000 meters in length can be realized.
The newly developed gyrocompass-based TUnIS navigation system for E-Power Pipe® allows ongoing position determination and high-precision control known from microtunnelling in the non-accessible diameter range. Combined with a magnetic field and a corresponding sensor, long distances can be thus be excavated precisely and existing installations such as pipelines, roads, railways and bodies of water can be crossed under safely.
The specially designed cutting wheel is equipped with extremely robust cutting tools. A cone crusher located behind it crushes boulders, rock or other materials to a pumpable grain size.
A magnetic sensor and a gyrocompass continuously identify the machine’s position underground to enable extremely precise control.
Hydraulic power pack
The integrated 22 kW hydraulic power pack supplies the main drive with the required hydraulic power.
Jet pump as slurry pump
An extremely high discharge velocity at the jet nozzle creates a suction effect that allows the muck-suspension mixture to be carried away over long distances.
Three hydraulic motors provide the power needed for the cutterhead to operate at up to 25 rpm.
Steel jacking pipes for thrust and supply
The temporary steel jacking pipes were designed specifically for E-Power Pipe®. They form a tension-resistant pipe string, and all the necessary lines e.g. for the slurry circuit, power supply and data transmission are also integrated. With a pipe length of 9 meters, high advance rates are achieved with the lowest possible number of coupling operations. The integrated pipe collar system simplifies the coupling process and reduces the time required for pipe installation (pipe changes) to just 10 minutes. An innovative connection system creates the compressive and tensile strength necessary for pushing the machine forward and pulling in the product pipe.
Jacking frame provides push and pull force
A rack & pinion jacking frame with a stroke of 10 meters and a push and pull force of 340 tonnes was designed specifically to match the jacking pipe. The force is transferred by an electrically driven carriage, which is fixed to the last jacking pipe at any given time via a thrust ring. Hydraulic cylinders integrated in the carriage brace the jacking frame in the launch shaft. No further conversion measures are therefore required for retracting the jacking pipes, both pulling and thrust forces are transferred similarly.
If space is limited, the lengths of the steel jacking pipes and the jacking frame can be adapted to suit the specific project.
The efficiency of the E-Power Pipe® method has already been demonstrated in several practical applications. Following the successful pilot project in 2017, E-Power Pipe® was used in further construction measures for the expansion of the grid in Germany. With its impressive advance rates, high planning reliability and environmentally friendly construction method, E-Power Pipe® scores well with grid operators, contractors and landowners.
The development of the method received funding from the Federal Ministry of Economics and Energy (BMWi research project IBoTec) and was carried out by Herrenknecht in cooperation with Amprion GmbH and RWTH Aachen.
E-Power Pipe® installation in the launch shaft with AVNS350XB tunnelling system and rack & pinion jacking frame
Installation of the AVNS350XB with 505 mm boring diameter and integrated jet pump
Breakthrough of the AVNS tunnelling system in the target shaft
E-Power Pipe® in operation in Bacharach, where 6 parallel cable protection pipes with a length of up to 700 m each were installed