________________ The pipe jacking method is based on a simple principle: the pipe string is driven from the launch shaft in the direction of the target shaft. Hydraulic jacks drive the tunnelling machine which is positioned at the tip. Once the thrust cylinders have reached their final position, they are retracted. The next tunnelling pipe is let down into the launch shaft, installed and then pushed forward. This process is repeated until the target shaft has been reached.
Trenchless tunnelling secures supplies without surface interference
Pipe jacking, which continues to be developed further, is a breakthrough, in particular for the installation and modernization of underground supply and disposal lines. Visible at the surface, a launch and a target shaft are set up at distances of up to 2,000 meters apart and more, depending on the nominal diameters of the pipes, the geological conditions, the pipe materials and the number of intermediate jacking stations. The jacking pipe is lowered into the launch shaft, installed at the tip of the pipe string and driven forward in the direction of the target shaft using hydraulic jacks. By repeating this process, the pipe string eventually reaches the target shaft. There, the tunnelling machine is recovered and prepared for the next operation. During trenchless tunnelling underground, urban life can carry on without interruption.
Trenchless tunnelling construction has many advantages because the surface remains almost completely unaffected by the pipe jacking operations. No major earth shifting is necessary at the tunnelling site and only a few shafts are required. This means in practice:
- almost no impact on nature or the environment
- almost no impact on traffic or roads
- almost no impact on residents by dirt and noise
- no risk of vibration for historic buildings
- greater transparency in terms of time and costs
As a market leader in trenchless tunnelling, Herrenknecht has been continuously expanding the possibilities of pipe jacking and its applications. This well-proven tunnel construction method contributes significantly to reducing the potential burdens during underground tunnel construction, and at the same time increases profitability significantly.