Construction of tunnels or pipes for use in civil engineering works

A tunnel or pipe section comprising a plurality of rectangular panels assembled together to form a closed figure, wherein each panel is of concrete reinforced by reinforcement comprising reinforcing rods of threaded form, at least some of the panels having embedded into the edges connectors which lie adjacent corresponding connectors of adjacent panels whereby adjacent panels of the section can be connected by bolting the adjacent connectors, wherein the connectors are of tubular form and of rectangular cross-section with four side walls, each of said side walls including an aperture intermediate the ends of the connector, some of said apertures receiving end portions of the threaded reinforcing rods whereby the ends of the rods lie within the interior of the connectors, and nuts on the threaded ends of the connectors, said nuts lying within the interior of the connectors whereby the connectors are anchored within the panels by being secured directly to the reinforcing rods, another one of said apertures and the corresponding side wall of the connector lying at the edge of the panel with the said side wall being substantially flush with the panel edge so as to lie in face-to-face relationship with the apertured side wall of a corresponding adjacent connector in an adjacent panel, the two adjacent connectors being bolted together by a bolted connection comprising a bolt extending between the facing side walls.