GB2157740A - Tunnel linings - Google Patents

Abstract

A tunnel lining ring comprises a plurality of segments 1-6, each having an arcuate body or skin and radially outwardly extending flanges at each circumferential end of the body, the flanges being adapted to receive fastening means 17 by which the plurality of segments may be secured together to form the ring, and segments 2-6 being provided with apertures 7-13 adjacent to the flanges to provide access to the fastening means. Radially outwardly extending additional flanges at each axial end of each segment having holes 15 to enable the ring to be secured to adjacent rings. <IMAGE>

Description

SPECIFICATION Tunnel linings This invention relates to tunnel linings.

Hitherto bolted segmental tunnel linings large enough to accommodate human beings have been constructed by progressively boring through soil and/or rock etc. and, as the soil is removed, piac- ing in position and bolting together arcuate segments which together form a ring and in turn securing this ring to its predecessor. Any voids formed 'behind' the ring are then filled with grout.

To accommodate the bolts, and add strength to the construction the segments are flanged and the flanges extend inwardly since the construction is effected from within.

In some circumstances the provision of inwardly extending flanges is an asset since they can be utilised for securing various services to the walls of the tunnel, e.g. cables etc. but in other cases they form an undesirable obstruction for example to the flow of fluids in sewage systems etc.

It is an object of this invention to provide an improved tunnel lining which may be readily constructed from within but which nevertheless provides a smooth interior surface free from obstruction.

According to the invention there is provided a tunnel lining comprising a plurality of arcuate segments having outwardly extending flanges at each end adapted to receive fastening means by which the segments are secured together to form a ring, access to the fastening means being effected from within through apertures adjacent to the flanges in the skin of the segments.

The fastening means may conveniently comprise screws or bolts the heads of which may be driven by a tool accessed through the skin apertures and operative to effect the drive through a right-angled coupling. Grout may be applied through the wall apertures in the conventional manner and the apertures may be sealed by plugs.

Preferably, the segments additionally have outwardly extending flanges at their two sides and each ring is secured to its predecessor by fastening means access to which is effected from within through the said apertures. In accordance with this invention then a tunnel lining is provided with a protrusion free inner surface and which can yet be constructed from bolted segments (and bolted rings) so as not be involve too radical a departure from accepted civil engineering practice in this field.

In order that the invention may be fully understood, one embodiment thereof will now be described with reference to the accompanying drawings, in which: Figure 1 is an axial section through a completed ring.

Figure 2 is a section along A-A in Figure 1.

Figure 3 is a section along B-B in Figure 1.

Figure 4 is a detail of a cross-joint between adjacent segments, and Figure 5 is a detail of a circle joint between two adjacent rings.

Referring now to Figures 1 to 3 in the drawings, six arcuate segments 1 to 6 are shown bolted together. Each segment is flanged at both its ends and its sides but there are three different types.

One segment (1) has no surface apertures but has threaded holes in its flanged ends. The two segments 2,3 to the left (clockwise) each have two apertures 7,8 adjacent their lower end flanges and clearance holes in these flanges with threaded holes in their upper end flanges and the two segments 4,5 to the right each have two apertures 9, 10 adjacent their lower end flanges and clearance holes in these flanges with threaded holes in their upper end flanges. Finally, the remaining segment (6) has four apertures 12,13, two adjacent each end flange and clearance holes in these flanges. Clearance/threaded holes 14, 15 are located in the side flanges of each segment adjacent each of said apertures and stiffening webs 16 are formed on the outer side of each segment between the skin and the end flanges.

A complete ring section as shown in Figures 1 and 2 is made up by initially placing segment 1 in position and then bolting to it in sequence the segments 2 and 3. Bolts 17 secure the flanges together, access to them being obtained through apertures 7 and 8 which are each large enough to permit the passage therethrough of a hand or tool to locate the bolt in the threaded hole; this location may be aided by the provision of a thin plastic collar between the flanges to retain the bolt in situ before final assembly. A power driven cranked tool is used for tightening the bolts.

Figure 4 shows a detail of the segment joint illustrating the bolt 17 and the clearance and tapped holes in the adjacent flanges; a bituminous packing piece 18 is located as a sealant between adjacent flanges. Segments 4 and 5 are then likewise bolted in position, access being effected through apertures 9 and 10 and finally the 'top' segment is placed in position and secured by bolts 17 via the two apertures 12 and 13. It will be appreciated from the drawings that none of the bolts is upwardly facing, thus facilitating assembly. The ring is secured to its predecessor by inserting bolts through the apertures adjacent to the trailing edge of the ring being built, through the clearance hole 14 into the threaded hole 15 and tightening up with the cranked tool as before.A detail of this circle (ring) joint is shown in Figure 5; as before a bituminous packing strip 19 is located as a sealant between the circumferential joint flanges. Caulking grooves 20 are formed on the inner surface between adjacent segments and between adjacent completed rings (21).

As the assembly progresses, cementitious grout is fed through the apertures into the voids between the outer wall of the lining and the surrounding soilírock and finally, the apertures are sealed and the joints caulked. To economise on the use of grout the outer pairs of the segments can be prefilled with low-density concrete, formed to maintain access through the apertures to the plain and threaded holes. Alternatively, after building the ring, initial void- filling with pea-gravel can be carried out and followed later with the injection of cementitious grout.

All the segments may be cast from spheridal graphite iron.

Although this invention has been described with reference to the specific embodiment illustrated it is to be understood-that various changes may be made without departing from the scope of this invention. For example, more, or less than the six segments may be used to make up a complete ring and the cross-section may not be circular e.g. it may be egg-shaped or in any other convenient form for sewerage or other purposes in mind.

Claims (9)

1. A tunnel lining segment having an arcuate body or skin and radially outwardly extending flanges at each circumferential end of the body; the flanges being adapted to receive fastening means by which a plurality of such segments may be secured together to form a ring; each segment body being provided with apertures adjacent to the flanges to provide access to the fastening means.

2. A segment as claimed in Claim 1 wherein the arial sides of the body are provided with additional radially outwardly extending flanges, which are adapted to receive fastening means whereby adjacent rings of segments may be secured together, each segment body being provided with apertures adjacent to the additional flanges to provide access to the fastening means.

3. A segment as claimed in Claim 1 or 2 wherein the flanges and additional flanges are apertured for the receipt of the fastening means.

4. A tunnel lining incorporating a plurality of lining segments as claimed in claim 3 wherein the fastening means comprises screws or bolts, the heads of which are adapted to be driven by a tool accessed through the apertures, which tools are operative to effect the drive through a right-angled coupling.

5. A tunnel lining as claimed in Claim 4 wherein grout is provided radially outwardly thereof by application through the apertures.

6. A tunnel lining as claimed in Claim 4 or 5 wherein the apertures are sealed by plugs.

7. A tunnel lining as claimed in Claim 4, 5 or 6, wherein sealant is provided between juxtaposed and fastened flanges of the segments.

8. Tunnel lining segments substantially as shown in and as hereinbefore described with reference to the accompanying drawings.

9. A tunnel lining substantially as shown in and as hereinbefore described with reference to the accompanying drawings.