GB2462881A

GB2462881A - Sewer linings

Info

Publication number: GB2462881A
Application number: GB0815682A
Authority: GB
Inventors: Robert Alan Walters
Original assignee: CHANNELINE INTERNAT Ltd
Current assignee: CHANNELINE INTERNAT Ltd
Priority date: 2008-08-28
Filing date: 2008-08-28
Publication date: 2010-03-03
Also published as: WO2010023468A1; GB0815682D0

Abstract

A lining section 1 for a sewer comprises a hollow tubular member 3 having first and second longitudinal ends. An outer surface of the lining section is provided with spacing elements 11 which protrude from the outer surface for spacing the outer surface from the walls of the sewer. The spacing elements 11 may take the form of parallel elongate skids and extends along a major portion of the longitudinal extent of the lining section 1. A resilient seal 9 may be provided for connecting an end of the lining section 1 to an end of a similar lining section. A method of lining a sewer comprises inserting the lining sections 1 into the sewer, manoeuvring the lining sections 1 along the sewer such that the spacing elements of the lining section slide along the walls of the sewer, and connecting the lining sections 1 together to form the sewer lining. The lining 1 may be covered with a high friction coating and grout may be inserted between the lining 1 and the sewer wall to fix the lining 1 in place. The tubular member 3 may be made of fibre reinforced polymer material and the spacing elements 11 may be formed of laminated timber.

Description

I

Sewer linings This invention relates to the lining of sewers, culverts, tunnels and the like.

Hereinafter, references to sewers shall be taken to include sewers, culverts, tunnels and the like.

Many existing sewers are primarily constructed of brick or similar materials.

Sewers of this type have in some cases been in operation for over a century and are in urgent need of replacement or of reconstruction. Sewers constructed more recently using concrete pipe sections are also increasingly in need of replacement or reconstruction. There is thus a considerable demand for improved systems for lining sewers, so that existing constructions can be stabilized and their useful working life extended. Such a lining should be economical to produce and to install. It should also be effective to withstand corrosive materials and capable of withstanding a desired degree of loading.

Sewers are dividable into two size regimes which determine which lining methods can be used. These regimes are "man-entry" and "non-man-entry".

When the cross-sectional size of a sewer is sufficiently large for a man to enter, then the lining can be installed in situ along the length of the sewer. For a non-man-entry sewer, the lining must be fed in from one end. Formal definitions for the threshold dimensions dividing man-entry from non-man-entry sewers exist, but these definitions vary from country to country. For example, in the United Kingdom the threshold is approximately 800mm by 500mm, and in Canada approximately 750mm by 500mm, for the largest and smallest transverse dimensions. In continental European countries such as Denmark, there is a larger threshold of approximately 1 meter diameter.

A prior art lining system for sewers is disclosed in GB-2087456-A. The system there described is primarily of use for the lining of man-entry sewers.

According to GB-2087456-A, the lining of a sewer is provided by means of curved sheets of plastics material. Longitudinally extending edges of the sheets are formed with interlocking tongues and grooves whereby the sheets may be assembled into a tubular body conforming to the cross section of the sewer.

Another prior art lining system is disclosed in EP-0569185-Al, which is primarily of relevance to the lining of non-man-entry sewers. According to EP- 0569185-Al, the lining of a sewer is provided by prefabricated tubular lining sections. The sections are formed as unitary bodies which are lowered into the sewer through an access pit before being moved into position along the sewer floor. End edges of the sections are formed with sockets and spigots which engage to form a sealed connection. The sealed connection may be provided by mastic and/or a resilient lining element.

There are a range of different load regimes to which sewer linings need to be adapted, these regimes being determined by the location and the structural integrity of the existing sewer. In some circumstances, it is sufficient for the sewer lining merely to withstand ground water loading, that is, the external hydraulic head. However, in the most demanding case, the lining needs to withstand not only ground water loading but also road and ground loading. In this case, the lining itself must form part of a composite load bearing structure with the sewer.

Where the lining itself must form part of a composite load bearing structure with a sewer, it must be shaped relatively closely to the dimensions of the sewer, and the gap between the lining and the sewer must be filled with a grout. In the man-entry case, the grout can be in-filled at locations along the sewer.

However, in the non-man-entry case, in-filling of grout presents a particular problem. The grout for all sections of the lining have to be forced into the sewer from the access pit. As the grout is highly viscous and has to pass through relatively small cross-sectional areas, the pumping pressure required is very high.

A problem associated with the prior art lining systems described above, and particularly with the system for use in non-man-entry sewers disclosed in EP- 0569185-Al, is that it can often be difficult to manoeuvre the lining sections into place once they have been lowered into the sewer. This problem is usually exacerbated by the desire to minimise the number of access pits when lining a given length of sewer, with the consequence that sections may need to be manoeuvred along large distances.

For example, a sewer which requires lining is likely to be in a state of structural disrepair. There are likely to be fallen bricks on the sewer floor, and there may be hanging bricks or structural relaxation of the sewer roof and sides. In sewers formed of concrete pipe sections the lateral alignment of the pipe sections may have shifted, leading to ridges or steps in the floor, roof and sides of the sewer. These protrusions from the sewer walls can catch on the lining sections as they are manoeuvred into place. In this way, the lining sections can be completely prevented from passing along the sewer, or the end edges of the sections can become damaged as they are manoeuvred over the protrusions, thereby compromising the sealed connection between sections.

Even when a sewer which requires lining is in a reasonable state of structural repair, friction between the lining sections and the sewer walls can be problematic. This problem is exacerbated by the increasingly common practice of providing the outer surface of the sewer sections with high friction coatings such as grit. These coatings are employed for the purpose of providing a good mechanical connection with the grout which is in-filled between the lining sections and the walls of the sewer.

According to an aspect of the invention, there is provided a lining section for a sewer, the lining section comprising a hollow tubular member having first and second longitudinal ends, wherein an outer surface of the lining section is provided with spacing elements which protrude from the outer surface for spacing the outer surface from the walls of the sewer, wherein the spacing elements extend along a major portion of the longitudinal extent of the lining section.

The spacing elements which protrude from the outer surface of the lining section serve to space the outer surface from the walls of the sewer. In this way, the outer surface of the lining section may clear the above described protrusions from the sewer walls as the lining section is manoeuvred along the sewer, thereby making it easier to install the lining section and minimising the risk of damage to its ends. The spacing elements may also reduce the contact area between the lining section and the walls of the sewer, thereby minimising frictional forces as the lining section is manoeuvred along the sewer.

Once the lining section has been manoeuvred into position, the spacing elements may serve to centralise the lining section in the sewer by providing an annular gap of controlled dimensions between the sewer walls on the outer surface of the lining sections. In this way, floating (buoying) of the lining section can be controlled when grouting between the sewer walls and the sewer lining, thereby enhancing the load bearing characteristics of the lined sewer.

The spacing elements may comprise a plurality of parallel skids extending in the longitudinal direction and arranged about the periphery of the lining section.

Skids, which are in the form of elongate rails, may enable the lining section to ride along the walls of the sewer with reduced levels of friction. Each skid will typically define an elongate surface for sliding contact with the walls of the sewer. In preferred embodiments of the invention, first and second longitudinal ends of the surface taper down towards the outer surface of the lining section.

For example, the ends of the skids may be chamfered.

Each skid may extend along at least an intermediate portion of the lining section, which intermediate portion is located midway between the first and second ends of the lining section. Such skids may additionally serve to strengthen the lining section against bending stresses which may be experienced as the lining section is manoeuvred along the sewer.

In a particularly preferred embodiment, each skid extends along substantially the entire longitudinal extent of the lining section without extending to the ends of the lining section. The possibility that the skids could extend beyond the endsof the lining section is not, however, excluded.

The outer surface of the lining section may be provided with a high friction coating, such as a grit. Such coatings advantageously provide a good mechanical connection with a grout once the lining section has been installed in the sewer. The lining section may alternatively or additionally be provided with a coating adapted for chemically and/or mechanically keying with the grout.

The spacing elements, such as skids, may have a maximum projection from the outer surface of the lining section of 10mm to 100mm, preferably 10mm to 60mm, and most preferably 20mm to 50mm. Such spacing elements have been found to provide a good compromise between maximising the flow capacity of the lined sewer and minimising the contact between the lining sections and the walls of the sewer while at the same time limiting the number of spacing elements required around the periphery of the lining section.

The tubular member of the lining section may be formed of a fiber reinforced polymer material, such as glass reinforced polyester (GRP). The cross sectional shape of the tubular member will depend on the shape of the sewer to be lined and may be circular or non-circular. Ovoid and egg-shaped sewers are common. Other composite materials are also suitable.

The tubular member and the spacing elements may together define a unitary body. For example, if the tubular member is formed of a fiber reinforced polymer material, then the fiber reinforced polymer material may also define the spacing elements.

The spacing elements may comprise lengths of timber, which may be attached to the tubular member by an adhesive, If the tubular member is formed of a fiber reinforced polymer material, then the timber spacing elements may serve as formers around which the fiber reinforced polymer material may be arranged.

At least one of the first and second ends of the lining section may be provided with a resilient seal arranged about the periphery of the tubular member, such that the first end is adapted to mate with the second end of a similar liming section in use. The resilient seal may be a rolling seal of the type disclosed in GB-2012889-A. The first and second ends of the lining section may be provided with a socket and a spigot or other form of connecting means.

The invention also provides a lined sewer comprising a plurality of the lining sections described above installed within a sewer.

According to another aspect of the invention, there is provided a method of lining a sewer, the method comprising: inserting into the sewer lining sections described above; manoeuvring the lining sections along the sewer such that the spacing elements of the lining section slide along the walls of the sewer; and connecting the lining sections together to form the sewer lining. The method may further comprising in-filling between the sewer walls and the sewer lining with a grout, to thereby enhance the structural characteristics of the lined sewer.

A specific embodiment of the invention will now be described in detail, by way of example only, with reference to the following drawings in which: Figure 1 is a schematic perspective view of a lining section for a sewer according to the invention; Figure 2 is a schematic lateral cross sectional view of the lining section shown in Figure 1; Figure 3 is a schematic longitudinal cross sectional view of the lining section shown in Figure 1; and Figure 4 is a schematic longitudinal cross sectional view of the lining section shown in Figure 1 being manoeuvred along a sewer.

The invention provides a lining section for a sewer. The Lining section comprises a hollow tubular member having first and second longitudinal ends.

An outer surface of the lining section is provided with spacing elements which protrude from the outer surface for spacing the outer surface from the walls of the sewer. The spacing elements extend along a major portion of the longitudinal extent of the lining section.

Figures 1 to 3 illustrate a specific embodiment of a lining section 1 according to the invention. The Figures are of a schematic type, and certain features have been emphasised to assist in the description thereof. Other features have been omitted from the Figures for the sake of clarity. Such features will be apparent to those skilled in the art.

The lining section 1 according to the invention comprises a hollow tubular member 3 having an outer surface. The tubular member 3 has substantially round inner and outer cross sectional shapes and is therefore suitable for lining sewers having a similarly sized round cross sectional shape.

The tubular member 3 is formed of glass reinforced polyester (GRP). It will be appreciated that the manufacturing procedure for this and similar materials allows for tubular members having different cross sectional shapes, which are suitable for lining differently shaped sewers. Ovoid and egg shaped cross sections are common, and tubular members having such cross sectional shapes are within the scope of the invention.

An outer surface of the tubular member is coated with a layer of grit (not shown) during the manufacturing procedure. The layer of grit provides a high friction surface capable of forming a good mechanical connection with a grout which is in-filled between the lining member I and the walls of a sewer once the lining section 1 has been installed.

A first end 5 of the tubular member 3 is formed with a socket (not shown in detail) and a second end 7 of the tubular member is provided with a spigot (not shown in detail). The socket and spigot facilitate the connection of the lining section 1 to similar lining sections within a lined sewer. The first end 5 of the tubular member 3 is additionally provided with a resilient ring seal 9. The resilient ring seal 9 is preferably formed of a closed cell elastomer. Isoprene and neoprene are suitable materials for the resilient ring seal 9. A rolling seal of the type disclosed in GB-2012889-A is particularly preferred. Another suitable seal is disclosed in EP-0569185-A.

The outer surface of the tubular member 3 is provided with spacing elements in the form of parallel elongate skids 11. The skids 11 protrude from the outer surface of the tubular member 3 for spacing the outer surface from the walls of a sewer.

The skids 11 are formed of straight lengths of timber which are longitudinally attached to the tubular member 3 with an adhesive during the manufacturing procedure. The lengths of timber may be pre-treated with a preservative, as is well known. The lengths of timber are over-laminated with the glass reinforced polyester material of the tubular member 3 so that the tubular member 3 and the skids 11 define a unitary body.

An important aspect of the invention is the size and shape of the skids 11. In particular, the skids 11 are sized and shaped so as to make manoeuvring the lining section 1 along a sewer as easy as possible. As shown in Figures 1 and 3, the ends of the skids 11 are chamfered so that the skids 11 taper down towards the ends of the lining section. These tapered ends help to prevent the skids 11 from catching on protrusions from the walls of the sewer, the skids 11 instead tending to riding up over or slide past the protrusions.

The cross sectional shape of the skids 11 is rectangular, although their surfaces may be provided with a slight degree of curvature so that they conform to the outer surface of the tubular member 3 and/or the walls of the sewer to be lined. The skids 11 may have a maximum projection from the outer surface of the lining section of 10mm to 100mm, preferably 10mm to 60mm, and most preferably 20mm to 50mm. In the example shown, the skids have a width of 60mm and a height of 40mm.

The skids 11 have a length such that they extend along substantially the entire longitudinal extent of the lining section 1, without extending beyond, and more preferably without extending to, the ends of the lining section 1. In particular, the skids 11 may extend at least along 60%, preferably 60% to 99%, and most preferably 75% to 95% of the longitudinal extent of the lining section 1. In the example shown in the Figures, the skids extend along 90% of the longitudinal extent of the lining section 1. Such skids 11 have been found to provide effective spacing of the tubular member 3 from the walls of a sewer, without interfering with the socket/spigot connection between adjacent lining sections 1.

The absence of the skids 11 from the ends of the lining section 1 helps to minimise the flow resistance when a grout is in-filled between the lining section 1 and the walls of the sewer.

Figure 2 illustrates the arrangement of skids 11 around the periphery of the tubular member 3. For the tubular member 3 having the circular cross sectional shape shown, the skids 11 are evenly spaced about the circumference of the tubular member 3. Where the cross sectional shape of the tubular member 3 is non-circular, it may be preferable to unevenly space the skids 11. In particular, regions of the cross sectional shape having a smaller radius of curvature are likely to benefit from more closely spaced skids 11 than regions of the cross sectional shape having a larger radius of curvature. In general, the arrangement of the skids should be so as to minimise the risk of contact between the outer surface of the tubular member 3 and the walls of the sewer to be lined. The number of skids 11 and their positioning will accordingly be dependent on the size and shape of both the tubular member 3 and the sewer to be lined. The positioning of skids may also depend upon to type and extent of disrepair in the sewer.

In use, the lining section 1 is typically lowered into a sewer to be lined through an access pit, which is constructed by opening a shaft in the ground to expose the walls of the sewer, and by removing an upper portion of the walls of the sewer. The lining section 1 is then manoeuvred along the sewer, as shown in Figure 4. The arrow shown in the figure indicates the direction in which the lining section 1 is manoeuvred.

A sewer which requires lining is likely to be in a state of structural disrepair.

There are likely to be fallen bricks on the sewer floor, and there may be hanging bricks or structural relaxation of the sewer roof and sides 13, as shown in the Figure. According to prior art lining methods, these protrusions from the sewer walls can catch on the lining sections as they are manoeuvred into place. In this way, the lining sections can be completely prevented from passing along the sewer, or the end edges of the sections can become damaged as they are manoeuvred over the protrusions, thereby compromising the sealed connection between lining sections.

According to the invention, the lining section 1 is provided with spacing elements in the form of skids 11 which serve to space the outer surface of the tubular member 3 from the uneven walls of the sewer 13. In this way, collisions with the protrusions from the walls of the sewer 13 may be avoided. The skids 11 also serve to minimise the contact area between the outer surface of the tubular member 3 and the walls of the sewer 13, thereby reducing frictional forces as the lining section is manoeuvred along the sewer. Such friction is undesirable because it not only increases the jacking forces required for manoeuvring the lining section, but can also damage the surface of the walls of thesewerl3.

In situations where a skid 11 comes into contact with a protrusion from the walls of the sewer 13, the lining section is able to ride over or slide past the protrusion by virtue of the chamfered ends of the skid 11.

Once the lining section 1 has been manoeuvred into position in the sewer 13, the above described procedure is repeated with additional lining sections of a similar type, with each section being connected to the others using the socket and spigot joints once they have been manoeuvred into place.

Once all of the lining sections for a given length of sewer 13 have been manoeuvred into place and connected together a grout is in-filled between the walls of the sewer 13 and the outer surface of the tubular members of the lining sections. The grout is injected between the walls of the sewer 13 and the outer surface of the tubular members as a paste comprising glass and resins. Upon curing to a solid, the grout forms a composite load bearing structure together with the walls of the sewer 13 and the lining sections. The skids 11 serve to maintain a relatively even thickness of the grout by preventing floating (buoying) of the lining sections as the grout is injected. In this way, the structural characteristics of the lined sewer 13 may be enhanced.

A specific example of the invention has been described above with reference to the Figures. Various modifications within the scope of the invention will be apparent.

For example, the invention has been described in the context of a non-man- entry sewer. The invention is, however, also applicable to the lining of man-entry sewers where these are lined using lining sections comprising tubular members, whether these are manufactured as unitary bodies or assembled from multiple components.

A specific form of grout is described above for in-filling between the walls of a sewer to be lined and the lining sections. Other grouts may, however, be suitable. For example, grouts comprising cements, sands and foams are suitable. The grout may also include additives, such as plasticisers, for modifying the properties of the grout

Claims

Claims 1. A lining section for a sewer, the lining section comprising a hollow tubular member having first and second longitudinal ends, wherein an outer surface of the lining section is provided with spacing elements which protrude from the outer surface for spacing the outer surface from the walls of the sewer, wherein the spacing elements extend along a major portion of the longitudinal extent of the lining section.
2. The lining section according to claim 1, wherein the spacing elements comprise a plurality of parallel skids extending in the longitudinal direction and arranged about the periphery of the lining section.
3. The lining section according to claim 2, wherein each skid defines an elongate surface for sliding contact with the walls of the sewer, wherein first and second longitudinal ends of the surface taper down towards the outer surface of the lining section.
4. The lining section according to claim 2 or 3, wherein each skid extends along at least an intermediate portion of the lining section, which intermediate portion is located midway between the first and second ends of the lining section.
5. The lining section according to any of claims 2 to 4, wherein each skid extends along substantially the entire longitudinal extent of the lining section without extending beyond the ends of the lining section.
6. The lining section according to any preceding claim, wherein the outer surface of the lining section is provided with a high friction coating for maximising a mechanical connection with a grout.
7. The lining section according to any preceding claim, wherein the outer surface of the lining section is provided with a coating adapted for chemically and/or mechanically keying with a grout.
8. The lining section according to any preceding claim, wherein the spacing elements have a maximum projection from the outer surface of the lining section of 10mm to 60mm.
9. The lining section according to any preceding claim, wherein the tubular member is formed of a fiber reinforced polymer material.
10. The lining section according to claim 9, wherein the tubular member and spacing elements define a unitary body.
11. The lining section according to any preceding claim, wherein the spacing elements comprise lengths of timber.
12. The lining section according to any preceding claim, wherein at least one of the first and second ends of the lining section is provided with a resilient seal arranged about the periphery of the tubular member, such that the first end is adapted to mate with the second end of a similar liming section in use.
13. The lining section according to any preceding claims, wherein the tubular member has a non-circular cross section.
14. A lined sewer comprising a plurality of the lining sections according to any preceding claim.
15. A method of lining a sewer, the method comprising: inserting into the sewer lining sections according to any of the preceding claims; manoeuvring the lining sections along the sewer such that the spacing elements of the lining section slide along the walls of the sewer; and connecting the lining sections together to form the sewer lining.
16. The method according to any preceding claim, further comprising in-filling between the sewer walls and the sewer lining with a grout.
17. A lining section, a lined sewer and/or a method of lining a sewer substantially as hereinbefore described and/or as shown in the drawings.