Vertical Shaft Sinking Machine (VSM)

Excavation and shaft construction in one step

Every Herrenknecht Shaft Sinking Machine consists of two main components – the shaft boring machine and the lowering units. The shaft boring machine is lowered into the launch shaft structure and attached firmly to the shaft with its three machine arms. A rotating cutting drum equipped with chisel tools is attached to a telescopic boom. This roadheader excavates and breaks the soil at the base of the shaft. The roadheader is telescopic, and can swivel up and down or rotate. Hence, the entire cross-section of the shaft plus an overcut can be excavated gradually. The excavated material is removed hydraulically through a submersible pump and transported to the separation plant on the surface. The lower concrete ring of the shaft structure, also referred to as the shaft’s cutting edge, is beveled and therefore cuts into the surrounding soil underneath. In addition, the overcut of the roadheader-like telescopic boom and cutting drum below the shaft’s cutting edge in combination with the bentonite lubrication in the annular gap reduce the frictional forces between the shaft wall and the surrounding soil. On the surface, 3 to 4 lowering units with hydraulic cylinders are attached firmly to the ring-shaped concrete foundation around the shaft. They are attached to the lower concrete base ring of the shaft structure by steel cables. In this way, the entire shaft structure can be held and lowered in a controlled manner during excavation. Ring building takes place simultaneously on the surface using prefabricated concrete segments. The simultaneous working processes (excavation, removal of excavated material, shaft construction, and lowering of the shaft structure) make it possible for VSM technology to achieve high advance rates of up to 5 meters per shift.