GB2342369A

GB2342369A - Tunnel sealing method and bolt therefor

Info

Publication number: GB2342369A
Application number: GB9821629A
Authority: GB
Inventors: Colin William John Rumble
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-10-03
Filing date: 1998-10-03
Publication date: 2000-04-12
Anticipated expiration: 2018-10-03
Also published as: GB9821629D0; GB2342369B

Abstract

The invention concerns a method of providing a water-tight seal between adjacent tunnel lining segments (1,2) of the type comprising an inwardly-directed flange (3) adjacent to each end thereof, such that the flanges at abutting edges of pairs of lining segments are spaced apart by a short distance, bolts (8) being fastened in a plurality of aligned holes in the adjacent flanges to secure adjacent segments together. The method comprises: <SL> <LI>(a) where necessary, removing existing sealing material from the mouth of the space (5) between adjacent flanges; <LI>(b) introducing a first sealing material (15) into the space between adjacent flanges to form a continuous body of the first material at least between the innermost edges of the flanges; <LI>(c) introducing into at least some of the aligned holes in place of the bolts, where present, special bolts (8) for introducing materials into the space between the flanges outwardly of the body of first material; <LI>(d) injecting under pressure via said special bolts a second sealing material (7) into the said space; and, preferably, <LI>(e) replacing each of said sealed means with a fastener. </SL> Also disclosed is a special bolt 8 with a passageway within it that allows sealant to be injected into an opening when the bolt is fasten between the flanges of a tunnel lining.

Description

TUNNEL SEALING METHOD AND BOLT THEREFOR Field of the Invention This invention relates to a method of providing a water-tight seal between adjacent tunnel lining segments, and to a bolt suitable for use in such a method.

Background to the Invention Many older tunnels, for example some of those in the London Underground system, are provided with cast iron linings formed in segments which are bolted together by means of inwardly-directed flanges. To form a water-tight seal between abutting segments, the flanges are spaced from the abutting edges by a small distance so that an annular space is formed between the adjacent flanges. A sealing or caulking material is then introduced into the annular space before the bolts are tightened.

With the passage of time, the sealing or caulking materials tend to break down and allow the ingress of water to the tunnel from the surrounding rock, clay or other ground. It is then necessary to re-seal the annular space between adjacent flanges. This has been a time-consuming manual task, with a high cost and variable rate of success.

Summary of the Invention According to the invention, there is provided a method of providing a watertight seal between adjacent tunnel lining segments of the type comprising an inwardly- directed flange adjacent to each end thereof, such that the flanges at abutting edges of pairs of lining segments are spaced apart by a short distance, bolts being fastened in a plurality of aligned holes in the adjacent flanges to secure adjacent segments together, the method comprising: (a) where necessary, removing existing sealing material from the mouth of the space between adjacent flanges; (b) introducing a first sealing material into the space between adjacent flanges to form a continuous body of the first material at least between the innermost edges of the flanges ; (c) introducing into at least some of the aligned holes in place of the bolts, where present, sealed means for introducing materials into the space between the flanges outwardly of the body of first material ; (d) injecting under pressure via said sealed means a second sealing material into the said space; and, preferably, (e) replacing each of said sealed means with a fastener.

Preferably, the first sealing material is a self-setting material, for example a cementitious material, which more preferably contains fibrous material to confer flexibility on the resultant body. The second material is also preferably a self-setting material, and while it may be the same as the first material it is preferably a polymeric material, which more preferably sets as a gel. Particularly suitable materials are hydrophilic methacrylate-based water-stop grouts and polyurethane hydroactive expanding grouts.

The sealing means preferably comprises a bolt and nut, the bolt having a passage extending therethrough from one end thereof to an opening on the side thereof intermediate the ends.

The fastener in step (e) is suitably a nut and bolt, preferably of stainless steel or other corrosion-resistant material.

Another aspect of the invention provides a bolt having a passage extending therethrough from one end thereof to an opening on the side thereof intermediate the ends, whereby a fluid may be injected into the passage from the said one end to flow out of the passage through said opening.

Yet another aspect of the invention provides a method of lining a tunnel com- prising positioning in the tunnel lining segments having inwardly-directed flanges adjacent to each end thereof, such that the flanges at abutting edges of pairs of lining segments are spaced apart by a short distance, the flanges being provided with aligned holes therethrough for receiving fixing bolts, the method comprising: (a) securing adjacent flanges together using bolts passed through some of the aligned holes and nuts fastened on to the bolts ; (b) introducing a first sealing material into the space between adjacent flanges to form a continuous body of the first material at least between the innermost edges of the flanges ; (c) introducing into the remaining aligned holes sealed means for introduc- ing materials into the space between the flanges outwardly of the body of first material ; (d) injecting under pressure via said sealed means a second sealing material into the said space; and, preferably, (e) replacing each of said sealed means with a fastener.

The method of the invention permits reliable sealing of joints between existing tunnel linings without the need to remove all the existing caulking material and with a substantial reduction in time and labour required as compared with conventional techniques. The bolts of the invention afford a straightforward and effective way of introducing sealant grout material into the annular space between the lining flanges.

Brief Description of the Drawings In the drawings, which illustrate an exemplary embodiment of the invention: Figure 1 is a part-sectioned cross-sectional view of a portion of a tunnel lining joint in accordance with the invention ; and Figure 2 is an exploded view of an alternative bolt to that shown in Figure 1, with associated washers and nut.

Detailed Description of the Illustrated Embodiments Referring first to Figure 1, the tunnel is lined with cast iron lining segments, of which portions of two adjacent segments 1 and 2 are shown in the Figure. Each segment has an inwardly-directed flange 3 extending therearound adjacent to the butt joint 4 between the segments 1 and 2 but spaced slighdy from it to form between the flanges 3 an annular space 5. At intervals around the flanges aligned pairs of holes 6 are used to secure the segments together using bolts and nuts. Conventionally, the segments were original assembled with a caulking material 7 filling the annular space 5 before the bolts were inserted to fasten the segments together. The caulking material 7 hardened to form a water-tight seal.

With time, the caulking material 7 has tended to become less effective, through shrinkage, vibration effects, and the like. In the method according to one aspect of the invention, the first step is to clean out the existing caulking material around the annular space to a depth just above the existing fixing bolts. Some of the fixing bolts are then removed at intervals around the lining periphery (it will be appreciated that some of the bolts may already have been lost), and are replaced by special bolts 8 having a central bore 9 therethrough extending from the end 10 of the bolt opposite to the head 11 and opening in a plurality of transverse ports 12 at a position corresponding to the centre of the annular space 5, when the bolts are in position in the flanges. The bolts 8 are provided with sealing washers 13 and are each fastened by a conventional nut 14.

The next step of the method is to fill the face of the annular space constituting the caulking joint with a cementitious fibre-filled caulking material 15 which is then al- lowed to set. A liquid water stop grout material is then injected through the bore of each of the special bolts 8 to fill any cracks and voids present in the annular space 5 behind the set caulking material 15. The grout material is suitably a hydrophilic methac rylate-based material which sets to form a gel. Since the form of the special bolts is such that they will be relatively costly to manufacture, it will typically be desirable to remove the special bolts after the grout material has set so that they can be re-used elsewhere, and to replace them with conventional bolts and nuts.

Figure 2 illustrates an alternative design of the special bolt, provided with cir- cumferential grooves 20 spaced at intervals along an unthreaded portion 21 of the shaft of the bolt, joined together by four equi-spaced longitudinal grooves 22 in the surface of the shaft, the transverse ports 12 from the central bore 9 opening into the grooves 22.

The circumferential and longitudinal grooves 20 and 22 serve to distribute the grout material more widely during injection, ensuring full dispersion of the material throughout the annular space beneath the caulking material 7.

It will be understood that, where the ingress of water into the tunnel is high, some action to inject sealant behind the linings may be necessary before the treatment described with reference to Figure 1 can be carried out.

Claims

1. A method of providing a water-tight seal between adjacent tunnel lining segments of the type comprising an inwardly-directed flange adjacent to each end thereof, such that the flanges at abutting edges of pairs of lining segments are spaced apart by a short distance, bolts being fastened in a plurality of aligned holes in the adjacent flanges to secure adjacent segments together, the method comprising: (a) where necessary, removing existing sealing material from the mouth of the space between adjacent flanges ; (b) introducing a first sealing material into the space between adjacent flanges to form a continuous body of the first material at least between the innermost edges of the flanges; (c) introducing into at least some of the aligned holes in place of the bolts, where present, sealed means for introducing materials into the space between the flanges outwardly of the body of first material; (d) injecting under pressure via said sealed means a second sealing material into the said space; and, preferably, (e) replacing each of said sealed means with a fastener.

2. A method according to Claim 1, wherein the first sealing material is a self-setting material.

3. A method according to Claim 2, wherein the first sealing material is a cementitious material.

4. A method according to Claim 3, wherein the cementitious material contains fibrous material.

5. A method according to any preceding claim, wherein the second material is a self-setting material.

6. A method according to Claim 5, wherein the second material is the same as the first material.

7. A method according to Claim 5, wherein the second material is a polymeric material.

8. A method according to Claim 7, wherein the polymeric material is such as to set as a gel.

9. A method according to Claim 8, wherein the polymeric material is selected from hydrophilic methacrylate-based water-stop grouts and polyurethane hydroactive expanding grouts.

10. A method according to any preceding claim, wherein the sealing means comprises a bolt and nut, the bolt having a passage extending therethrough from one end thereof to an opening on the side thereof intermediate the ends.

11. A method according to any preceding claim, wherein the fastener in step (e) is a nut and bolt.

12. A method according to Claim 10 or 11, wherein the nut and bolt are formed of stainless steel or other corrosion-resistant material.

13. A bolt having a passage extending therethrough from one end thereof to an opening on the side thereof intermediate the ends, whereby a fluid may be injected into the passage from the said one end to flow out of the passage through said opening.

14. A method of lining a tunnel comprising positioning in the tunnel lining segments having inwardly-directed flanges adjacent to each end thereof, such that the flanges at abutting edges of pairs of lining segments are spaced apart by a short distance, the flanges being provided with aligned holes therethrough for receiving fixing bolts, the method comprising: (a) securing adjacent flanges together using bolts passed through some of the aligned holes and nuts fastened on to the bolts; (b) introducing a first sealing material into the space between adjacent flanges to form a continuous body of the first material at least between the innermost edges of the flanges ; (c) introducing into the remaining aligned holes sealed means for introducing materials into the space between the flanges outwardly of the body of first material ; (d) injecting under pressure via said sealed means a second sealing material into the said space; and, preferably, (e) replacing each of said sealed means with a fastener.

15. A method of providing a water-tight seal between adjacent tunnel lining segments of the type comprising an inwardly-directed flange adjacent to each end thereof, such that the flanges at abutting edges of pairs of lining segments are spaced apart by a short distance, bolts being fastened in a plurality of aligned holes in the adjacent flanges to secure adjacent segments together, substantially as described with reference to the drawings.