Sink shaft method
The sink shaft method is suitable for bringing down shafts in loose rock .
In this process, a shaft is usually first sunk by using a hoe , shovel or excavator to remove loose surface layers. On the sole of a foreshaft is Senkschuh made of wood or iron mounted on the right then the wall of the Senkschachtes in the form of masonry, reinforced concrete or Küvelage is established. As the excavation work progresses on the bottom of the shaft, the sink shoe including the shaft structure sinks into the rock under its own weight. In doing so, however, the level of the cutting shoe must not be undermined, since otherwise loose rock could possibly flow in outside the shaft body. If cavities formed beyond the extension, this would severely impair the stability of the shaft. When it sinks, the height of the shaft crown is maintained at regular intervals by building up new rows of stones, adding new concrete casting or placing a new basin layer, so that the shaft is always expanded over the entire depth .
Advantages of the cesspool method
Sink shafts are always equipped with extensions over the entire depth of the shaft, so that there is no need for later extensions. Due to the cutting shoe, the expansion is always a little ahead of the sinking, which leads to increased safety compared to other possibilities of shaft sinking. The advance shaft construction also reduces the occurrence of dangerous water ingress; In principle, these are only possible at the bottom of the shaft and can thus be more easily checked. The installation of the shaft extensions will also take place comfortably close to the surface or, in the case of shafts that are 'nested', in a secured area, so that the safety of the miners is guaranteed to a greater extent.
Disadvantages of the cesspool method
The achievable depth of the cesspool process is usually not particularly great. Especially in the case of shaft construction through masonry, the increase in friction with advancing depth contributes to the fact that normally no depths of more than 50 m are reached in individual shafts. Measures to reduce friction, such as the installation of boards with a soft soap coating on the outside of the masonry or the Küvelage, can postpone this problem, but not significantly alleviate it. In the event of a stagnation, the sinking can be promoted by mounting presses on the shaft crown; however, this is limited by possible damage to the then heavily loaded shaft lining. In addition, it is difficult to predict the depth that can be reached, which makes the planning of the manholes somewhat more difficult. Even when using Küvelage, depths of more than 150 m per individual shaft were seldom reached. Larger depths can indeed be achieved by telescopically nesting several lowering cylinders; however, the resulting shaft diameter decreases accordingly. In greater depths, however, iron countersunk cylinders are preferred, as they can be brought down with less wall thickness and also withstand high rock pressures better.
literature
- Emil Stöhr, Emil Treptow : Basics of mining science including processing. Spielhagen & Schurich publishing house, Vienna 1892
- Fritz Mohr: shaft construction technology . Hermann Hübener Verlag KG Goslar 1964
- Association for mining interests in the Oberbergamts district Dortmund: The development of the Lower Rhine-Westphalian hard coal mining in the second half of the 19th century. Julius Springer's publishing bookstore, Berlin 1902