Abstract: A form for a concrete tunnel lining usable behind a tunnel excavator with a traveling shield is made of an inner tunnel-lining sheathing and a form front. The inner tunnel-lining sheathing is divided into a plurality of sheathing segments or rings movable independently of each other with intervening segment-bridging yieldable joints. The form front located between the traveling shield and the inner tunnel-lining sheathing is movable forwardly by the conrete which presses in the annular space formed by the traveling shield and/or the surrounding earth and by the inner tunnel-lining sheathing as well as the form front. An operationally beneficial design results when the inner tunnel-lining sheathing is set up for forward motion of the sheathing segments in the tunnel longitudinal direction singly or in groups one after the other relative to the remaining sheathing segments held or remaining at rest.

Abstract: A process for lining a tunnel with concrete behind a tunnel excavator having a for front advanced along with an excavator head in which the concrete is forced between the surrounding subterranean geological structure and an inner tunnel-lining form through a form front which rides sealingly on the outer surface of the inner tunnel-lining form and on the inner surface of the shield. Simultaneously, the form front, which is longitudinally movable relative to the shield, moves forward relative to the inner tunnel-lining form. The form front is movable forward simultaneously balancing the friction forces occurring between the form front and the shield and the inner tunnel-lining form. Satisfactory results are obtained when the friction forces between concrete sections of a predetermined length are measured by moving the form front relative to the stationary shield and the inner tunnel-lining form during an interruption in concrete feed.