GB2099479A

GB2099479A - Improvements in or relating to arcuate tunnel lining segments

Info

Publication number: GB2099479A
Application number: GB8114645A
Authority: GB
Original assignee: Charcon Tunnels Ltd
Current assignee: Charcon Tunnels Ltd
Priority date: 1981-05-13
Filing date: 1981-05-13
Publication date: 1982-12-08

Abstract

The disclosure relates to an arcuate concrete tunnel lining segment having an arcuate PVC plastics shell (11) extending over its inner surface. The shell (11) has outwardly extending side walls (12) overlying the sides of the segment. The outer circumferential edges of the side walls are formed with inwardly directed T-section ribs (13) formed integrally with the side walls and bonded into the concrete segment and the outer surface of the shell is formed with a similar multiplicity of spaced T- section ribs (14) likewise bonded into the concrete of the segment. The shell protects the concrete segment against attack from corrosive substances which would otherwise degrade the concrete. <IMAGE>

Description

SPECIFICATION Improvements in or relating to arcuate tunnel lining segments This invention relates to arcuate tunnel lining segments.

The invention provides an arcuate tunnel lining segment formed, in a cast aggregate material and having a protective plastics arcuate shell extending over the inner surface thereof, the shell having a plurality of key elements extending over the outer surface thereof which are cast into the lining to hold the shell on the lining and having side walls extending at least partway over the circumferential sides of the lining, the side walls also having key elements thereon cast into the aggregate lining.

Preferably each side wall of the protective shell has a key element extending along the edge of the wall remote from the arcuate shell.

It is also preferred that the arcuate shell has a multiplicity of key elements extending over the outer surface thereof between the respective side walls parallel to the axis of the arcuate shell.

The elements may be T-shape in transverse cross section.

Preferably the shells are formed from PVC.

The following is a description of one specific embodiment of the invention reference being made to the accompanying drawings in which: Figure 1 is a sectional view through part of a ring of tunnel lining segments according to the invention; Figure 2 is a section on the line A-A on Figure 1;and Figure 3 is a perspective view of an inner plastics protective shell of each segment of the ring.

The drawings show a ring of a tunnel lining made up of a nurnber of arcuate segments indicated generally at 10 each comprising an arcuate concrete casting and, around the inner surface of the casting, an arcuate PVC plastics shell 11 best seen in Figure 3.

The shell 11 has outwardly extending side walls 12 around its circumferential edges and the outer edges of the side walls remote from the shell are formed with inwardly directed T-section ribs 1 3 formed integrally with the side walls. The outer surface of the shell is formed with a multiplicity of integral closely spaced I-section ribs 14 extending across the surface from side wall to side wall generally parallel to the axis of the arcuate shell.

In the casting of each arcuate tunnel lining segment 10, the shell 11 is located in the mould with the shell against the inner surface of the mould and is filled with concrete in conventional manner. The concrete envelops the I-section ribs 1 3 and 14 so that the shell is firmly secured to the finished concrete liner. As can be seen from the section of Figure 2, the side walls of the liner extend part-way up the side edges of the casting and are flush with the surface of the casting. In the case where the circumferential end faces of the linings are formed with shallow recesses adjacent the inner surface of the lining as indicated at 1 5 on Figure 1, the shell and its side walls are correspondingly recessed as indicated at 1 6 in Figure 2.

When the segments are assembled together to form the tunnel lining, PVC strips 1 7 are welded over the joints between adjacent segments in each ring adjacent rings along the lining to prevent ingress of fluids between the joints which could attack the exposed concrete surfaces behind the joints. Instead of butt welding a strip over the circumferential edges of the adjacent segments, caulking may be inserted between the adjacent edges of the segments to fill the joints and prevent ingress of liquid.

The protective liner around the inner surface of the segments prevents chemical attack on the concrete of the segments. For example hydrogen suiphide gas given off by the sewage can condense on the upper surface of the tunnel to form hydrogen sulphate acid which will attack concrete. Such attack is prevented by the PVC plastics shells of the inner surfaces of the segments. The shells may of course be made from plastics other than PVC, provided they are capable of offering the necessary resistance to chemical attack from gases /liquids in the tunnel.

1. An arcuate tunnel lining segment formed in a cast aggregate material and having a protective plastics arcuate shell extending over the inner surface thereof, the shell having a plurality of key elements extending over the outer surface thereof which are cast into the lining to hold the shell on the lining and having side walls extending at least partway over the circumferential sides of the lining, the side walls also having key elements thereon cast into the aggregate lining.

2. A tunnel lining as claimed in claim 1 wherein each side wall of the protective shell has a key element extending along the edge of the wall remote from the arcuate shell.

3. A tunnel lining as claimed in claim 1 or claim 2 wherein the arcuate shell has a multiplicity of key elements extending over the outer surface of the shell between the respective side walls thereof parallel to the axis of the arcuate shell.

4. A tunnel lining as claimed in any of the preceding claims wherein the elements are of T-shape in transverse cross-section.

5. A tunnel lining as claimed in any of the preceding claims wherein the shell is formed from PVC.

6. A tunnel lining as claimed in any of the preceding claims wherein the side walls of the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to arcuate tunnel lining segments This invention relates to arcuate tunnel lining segments. The invention provides an arcuate tunnel lining segment formed, in a cast aggregate material and having a protective plastics arcuate shell extending over the inner surface thereof, the shell having a plurality of key elements extending over the outer surface thereof which are cast into the lining to hold the shell on the lining and having side walls extending at least partway over the circumferential sides of the lining, the side walls also having key elements thereon cast into the aggregate lining. Preferably each side wall of the protective shell has a key element extending along the edge of the wall remote from the arcuate shell. It is also preferred that the arcuate shell has a multiplicity of key elements extending over the outer surface thereof between the respective side walls parallel to the axis of the arcuate shell. The elements may be T-shape in transverse cross section. Preferably the shells are formed from PVC. The following is a description of one specific embodiment of the invention reference being made to the accompanying drawings in which: Figure 1 is a sectional view through part of a ring of tunnel lining segments according to the invention; Figure 2 is a section on the line A-A on Figure 1;and Figure 3 is a perspective view of an inner plastics protective shell of each segment of the ring. The drawings show a ring of a tunnel lining made up of a nurnber of arcuate segments indicated generally at 10 each comprising an arcuate concrete casting and, around the inner surface of the casting, an arcuate PVC plastics shell 11 best seen in Figure 3. The shell 11 has outwardly extending side walls 12 around its circumferential edges and the outer edges of the side walls remote from the shell are formed with inwardly directed T-section ribs 1 3 formed integrally with the side walls. The outer surface of the shell is formed with a multiplicity of integral closely spaced I-section ribs 14 extending across the surface from side wall to side wall generally parallel to the axis of the arcuate shell. In the casting of each arcuate tunnel lining segment 10, the shell 11 is located in the mould with the shell against the inner surface of the mould and is filled with concrete in conventional manner. The concrete envelops the I-section ribs 1 3 and 14 so that the shell is firmly secured to the finished concrete liner. As can be seen from the section of Figure 2, the side walls of the liner extend part-way up the side edges of the casting and are flush with the surface of the casting. In the case where the circumferential end faces of the linings are formed with shallow recesses adjacent the inner surface of the lining as indicated at 1 5 on Figure 1, the shell and its side walls are correspondingly recessed as indicated at 1 6 in Figure 2. When the segments are assembled together to form the tunnel lining, PVC strips 1 7 are welded over the joints between adjacent segments in each ring adjacent rings along the lining to prevent ingress of fluids between the joints which could attack the exposed concrete surfaces behind the joints. Instead of butt welding a strip over the circumferential edges of the adjacent segments, caulking may be inserted between the adjacent edges of the segments to fill the joints and prevent ingress of liquid. The protective liner around the inner surface of the segments prevents chemical attack on the concrete of the segments. For example hydrogen suiphide gas given off by the sewage can condense on the upper surface of the tunnel to form hydrogen sulphate acid which will attack concrete. Such attack is prevented by the PVC plastics shells of the inner surfaces of the segments. The shells may of course be made from plastics other than PVC, provided they are capable of offering the necessary resistance to chemical attack from gases /liquids in the tunnel. CLAIMS

6. A tunnel lining as claimed in any of the preceding claims wherein the side walls of the shell extend only part way across the circumferential edges of the lining and are flush with the edges.

7. A tunnel lining substantially as described with reference to and as illustrated in the accompanying drawings.