Tunnel construction under undisturbed earth surface - involves excavating tunnel core while prefab. roof sections are inserted on initially sunk side walls

摘要

In the tunnel construction below a layer of ground which remains undisturbed, side walls are introduced from above. Prefabricated roof sections (5) are positioned on the side walls (2) which terminate at the correct height for the roof bearing surfaces (4). The earth core is excavated at the same time. Roof sections can be inserted resting on prefabricated bearing heads, set on top (3) of the side walls, with sliding or rolling bearings to absorb horizontal and vertical forces. They can be inserted from a starter shaft (6).