(Image: Entry of a jacking machine into an unlined target shaft secured by means of a slope in rock [FI-Herreb])

Independently of the geology, excavation from a slope is only possible with open shields without greater additional measures. The methods that can be used are microtunnelling machines with auger spoil removal as well as hand and shields with mechanical partial excavation (Abschnitt 9.2.1) in the diameter range to 3 m [Konra01].

During the …

The exit and entry openings for the microtunnelling or shield machine are created in shafts with removable linings by the partial removal of the lining in the region of the openings. In all cases, it must be ensured that the subsoil in the region of the openings is (either naturally or by measures taken previously) free of …

With rigid lining types (e.g. (bored) pile walls, diaphragm walls, segmental linings (Bild 12.8.1.3)), safe exit without additional improvement of the subsoil is usually not possible. During the creation of the opening, it is possible that the latent danger of existing ground failure caused by the utilization of heavy excavation equipment by hand is increased by the corresponding vibrations [Konra01].

Besides the creation of the exit opening by hand …

Open sinking shafts of shaft rings or shaft elements (Abschnitt 12.6.2.2) are usually equipped at the works with the project-specific exit and entry openings in prefabricated base units or shaft rings whereby the openings themselves are provisionally closed during the sinking procedure .

Thus, the following issues must be taken into account by the seal of the opening [Thale99] :

• Traversal and removal of the microtunnelling machine
• Sufficient bending …

(Image: Exit lock in the form of a closed pressure chamber flanged to the starting shaft [Stein05a])

In this variant, a pressure resistant steel container is fastened to the inside wall of the shaft and this is closed to the inside wall of the shaft by means of a blind flange and at the outer side by means of a removable lining in the form of sheet piles or the special prepared lining region for traversal of the microtunnelling or shield machine in …

A special solution for microtunnelling with nominal sizes of jacking pipes up to a maximum of DN/ID 800 is the closed pressure chamber (Bild 12.8.2.2.2) (Bild 12.8.2.2.2) (Bild 12.8.2.2.2) (Bild 12.8.2.2.2) (Bild 12.8.2.2.2) (Bild 12.8.2.2.2). This closed pressure chamber is integrated into the shaft face from open sinking shafts, which are made of prefabricated reinforced concrete shaft rings (Abschnitt 12.6.2.2) (Abschnitt 12.8.1.4), by the factory.

(Image: Open pressure chamber welded to the inside of the shaft)

Open pressure chambers welded into the shaft find particular application in sheet pile linings (Bild 12.8.2.2.3).

The pressure chamber is sealed to the inside of the shaft by means of a steel box open welded to the sheet pile wall and open at the top. The top edge of the steel box must be above the maximum level of groundwater to be expected. The opening of the pressure chamber to the …

For pipe jacking of larger …

When using closed sinking shafts (Abschnitt 12.6.1) as starting or target shaft, it is feasible at the exit and entry phases to use the existing compressed air equipment (Bild 12.8.2.3). In this case, the pressurized shaft acts as a compressed air chamber for supporting the in-situ groundwater pressure when opening the exit or entry opening.

The exit and entry openings are previously created during the construction of the reinforced concrete sinking …

With trenchless pipeline construction methods, it is now possible to install cables and pipelines underground, irrespective of the outer diameter or nominal size and the geological and hydrogeological boundary conditions. The wide-ranging technical information in this standard reference book not only helps the user in the planning and execution of pipeline construction measures, but also provides a basis for an economically and technically optimal selection of the process technology. In detail, the technical book deals with the following topics: geotechnical fundamentals and investigations, unmanned, steerable and non-steerable methods (soil displacement methods, pilot pipe jacking, microtunneling, manned methods (pipe jacking), drilling fluids and drilling fluid technology, jacking control, surveying and monitoring, start and target shafts, calculation of jacking pipes, tendering and contract award information, and economic feasibility considerations.