Abstract: A tunnel having an inner surface and extending along an axis is lined with pumpable concrete having a predetermined hardening time and by a form having an annular inner wall and an axially movable front wall. Substantially equal sized batches of pumpable concrete are successively injected into the space through the movable front wall through a plurality of angularly equispaced ports therein. The batches are injected axially backwardly through the ports at such a rate that succeeding batches are injected through each port at a time interval that is substantially smaller than the concrete hardening time. The front wall is displaced forward at such a rate and the batches are sized such that each batch spreads over a predetermined axial and a predetermined angular distance, such that the latter is greater than the former.

Abstract: For continuously lining a tunnel with extruded concrete a pumping device for feeding the concrete and a form having an interior form member and a forwardly movable form front are employed. The extruded concrete is put into place without clump formation, when it is provided in equal-sized segments in a plurality of equal constant amounts which are fed in succession one after the other circumferentially in a time interval which is small compared to the hardening time of the concrete. For this purpose the form front is provided with a plurality of concrete input ports uniformly distributed circumferentially and connected with the pumping device, while the pumping device is designed to service the concrete input ports in succession one after the other circumferentially.

Abstract: A movable wall delimiting a space into which concrete is pumped between a shield lining a tunnel wall and an inner form is advanced by the concrete pressure relative to the shield. This movable wall can be braced by adjustable spring force relative to the shield.