Background information:
Where tunnel boring machines are used, trapezoidal concrete elements must also be used to stabilise the tunnel walls. Of course, the dimensions of these elements can vary because the diameter of the drilled hole can also vary. But there are certainly many similarities in the main lines.
Construction details:
The prefab concrete tunnel wall elements are custom-made for the tunnel where they are used. However, almost all elements have rubber edges along the end faces that should prevent leaking groundwater. They are also almost always equipped with holes for large bolts with which the elements are secured to the previously placed ring of the same concrete elements.
The Markenburg plates are originally straight, but can be bent fairly easily to almost any desired radius. The edges are shaped in such a way that they can be easily connected to.
