Widening concrete lining and tunnel - includes supporting existing lining and new tunnel driven alongside and concreted

摘要

A tunnel widening system includes driving and lining the widened tunnel tube while the lining of the existing tunnel is held in position by two longitudinal beams above each other. The beams are pressed against the lining by provisional or permanent props. Subsequently a further tunnel tube is driven along the existing tunnel tube and the new tunnel tube immediately lined with sprayed concrete. The sprayed on lining is supported together with the lining of the existing tunnel in position by the longitudinal beam and props. During progress of driving the new tunnel, the not needed parts of the existing tunnel lining are removed.