GB1288393A - - Google Patents

Abstract

1288393 Lined tunnels WILLIAM F REES Ltd 4 June 1970 [4 Sept 1969] 43907/69 Heading E1F A method of constructing a lined tunnel comprises erecting a lining ring from three 120‹ lining segments within a tunnel shield, centering the ring within the shield, joining the ring to the previously erected ring, advancing the shield, and injecting a filler material into the annular void between the ring portion extending from the shields' rear and the surrounding material while the ring is supported co-axially with the shield by the shield. The ring is erected by placing a first segment within the shield, engaging one circumferential end of each of two further segments with the respective circumferential ends of the first segment, and pivoting the two further segments outwards to form the ring. The first ring is preferably placed on the bottom of the shield. The ring is erected, Fig. 1, within skirt 24 of shield 20, the tubular loop 23 is inflated to raise and centralise the ring, and the ring is then moved by jacks 21 to abut previously laid ring 26 to which it is then joined. Hardwood shield ring 27 maintains radial pressure on the ring. The tunnel is further excavated, the shield advanced, hoop 23 deflated, and a filler 28, e.g. high alumina cement grout, is injected through holes in the previously laid ring. A steel hoop 30, Fig. 9, may be contracted onto the ring to maintain radial pressure on the ring, the hoop being tensioned by a wedge 35 driven through a loop in the hoop. To ensure that the rings will crack at predetermined places each ring has one or more equi-spaced "V" shaped, or similarly shaped, notches extending axially on its inside surface, with similar notches in corresponding positions on its outside surface. Reinforced concrete and glass - reinforced - plastic segments are exemplified.