GB2284623A

GB2284623A - Filling of spaces

Info

Publication number: GB2284623A
Application number: GB9323589A
Authority: GB
Inventors: Barry France
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-11-16
Filing date: 1993-11-16
Publication date: 1995-06-14
Anticipated expiration: 2013-11-16
Also published as: GB9323589D0; GB2284623B

Abstract

A method of filling spaces between the lining segments B of a tunnel and a substrate, wherein a flexible bag 2 is secured to the outer face of each segment to cover the area of the segment, and a filler material is supplied through a hole 6 in the lining segment to expand the bag thereby filling the space. <IMAGE>

Description

FILLING OF SPACES The invention relates to the filling of a space in tunnelling construction, building, civil engineering or mining. For convenience the invention will be described with reference to the filling of an annulus between the bore wall and the segmental lining of a tunnel, but the invention is not limited to this use.

It is well known to provide a throughhole in the wall of a segment of a tunnel lining and to inject a cementitious or bentonite grout through the hole to fill the annulus.

This technique can be expensive because of the materials used and can be unreliable if because of water ingress or loose debris in the annulus a weak or incomplete grouted structure is formed, as this would necessitate a secondary grouting operation. It is also known to inject the materials into a bag placed in the annulus during the segment erection process but the present technique is slow and unreliable owing to operator error. It is also limited to the use of Tunnel Boring Machines (TBM's) without shields.

According to the invention in one aspect there is provided a method of filling the space between the wall of a substrate and a lining which extends generally parallel to the wall and is made up of lining units arranged in side-by-side relation, each unit comprising a block having a throughhole, a flexible bag being connected to one face of the block, the method comprising placing the blocks alongside the wall with the bags facing the wall and then supplying via the throughhole sufficient filler material to expand the bags to fill the space.

Preferably the bag is secured to the associated block by at least one releasable connector which retains the bag in a collapsed condition but which allows the bag to expand when the filler material is supplied therein. Preferably the bag is secured by sufficient connectors to hold the flexible bag generally flattened and parallel to the one face of the block. Most preferably the bag is folded or pleated when in the flattened condition. In a preferred feature the bag is dimensioned so that the area thereof when full exceeds that of the block to which it is connected. The bags can be attached to the blocks at any convenient time prior to the positioning of the blocks alongside the wall.

Preferably the filler material is a self-setting grouting composition, most advantageously the composition comprises a hydraulically settable filler and water.

In one embodiment of the invention the composition is substantially free of cement which is an expensive material and preferably, in this embodiment, the composition comprises PFA, fly ash and water. Preferably the bag is formed of a Geotextile material or a water impenetrable material.

When used with a Geotextile bag, the filler material may be selected from a wide range of particulate solids suitable as inflects to match the inherent geological conditions.

Thus, while cementitious materials may be used, the invention allows use of non cementitious materials and, as indicated above, a polymer-stabilised material such as PFA can be used without cement. A Geotextile bag will allow the grout to bleed and lose water from the bag while the remainder of the grout consolidates to a hard mass.

In an alternative embodiment the solid filler material may be a cementitious, low density cellular grout. The density of the set grout may be below 800 Kg/m3 and may be as low, for example, as 300 Kg/m3. The grout can conveniently be supplied from a grout mixer used in a continuous mode whereby a prefoaming machine blends the foam and grout together to produce a lightweight cellular grout whose density can be varied as required.

The invention also includes a lining unit comprising a block of concrete or the like having two opposite major faces, a hole extending through the body from one face to the other, a bag of flexible material being secured to one face of the block by a releasable connector.

The invention further includes a tunnel comprising a tunnel ring in a bore with an annulus in between, the ring being built up of lining blocks arranged in side-by-side relation, each block having a throughhole, a flexible bag being connected to one face of the block, the bags facing the wall and being filled with sufficient filler material to expand the bags to fill the annulus.

In order that the invention may be well understood it will now be described byway of example with reference to the accompanying diagrammatic drawings in which: Figure 1 is an end elevation of part of a tunnel ring comprising segmental blocks of the invention each having a flattened bag on one face; Figure 2 is a perspective view of one block from above and the rear; Figure 3 is an end elevation as Figure 1 in which the bags have been filled.

The tunnel ring R of Figures 1 and 3 is built up of a number of segmental blocks B which arranged in side-by-side abutting relation. The ring R is present in the bore E and there is an irregular annular gap A between the wall of the bore and the ring R to be filled. Each block B is cast of a concrete and has a through bore 1 which may house a plastics or steel threaded sleeve, not shown, to receive a lifting bolt, not shown. The sides of the blocks may be shaped to interengage in known manner.

Each block is generally rectangular as seen in front view.

According to the invention a bag 2 of a Geotextile material or impenetrable plastics material is located on the near face of each block. Each bag is of generally rectangular shape corresponding in area and slightly larger than that of the associated block. Eyelets 3 are formed in the corners of the bag and straps 4 connect the corners of the bag to the corners of the block. The straps can take the form of plastic plugs anchored into sockets cast in the block. Each plug can be pushed through an eye (not shown) in the bag to which is also attached a fabric strap. Both the fabric straps and the plugs are designed to shear when the bag expands to ensure unfolding of the bag. The bag has a width larger than the gap of the annulus A but is folded or pleated at 5 be generally flat and is held in the flattened condition by the straps. A spout 6 is present in one wall of the bag and extends into the bore 1.

In use the blocks B are placed ion each other to form the ring with the bag 2 of each block facing the annulus A. A filler material is supplied, e.g. injected through the spout 6 in the bore 1 into each bag. The pressure breaks the straps 4 so that the bag can expand, i.e. unfold to fill the annulus. Because in the filled condition the bag is oversize relative to the associated block B the joint line Q between neighbouring bags 2 is offset relative to the joint line J between the blocks to provide an extra seal.

The filler material may be selected from a wide range of particulate solids suitable as infills. While cementitious materials can be used there is no need to use such expensive materials; instead a setting material such as pulverised fly ash can be injected with water; some water will escape through the porous wall of the Geotextile bag and the remainder will react with the fly ash to form a hardened mass.

Thus it can be seen that the invention provides a method of grouting using a bag in an annular void or space between a tunnel bore and a segmental lining therein, where the annulus may be subject to static or severe water ingress and/or weak, fragmented ground conditions.

The invention offers many advantages. The bag will expand to fill the adjacent portion of the annulus and prevent washout of injected material. The bags can be attached to the segments or blocks and the blocks can be transported to the site and erected with the bags in position. The connectors allow the bag to expand during filling to completely fill the void even though the ground may have collapsed onto the bag, thereby ensuring no restriction to the flow of grout. The filled bags around a segmental ring provide pressure equalisation and overlapping of the joints giving improved seals.

TBM's designed for bad ground conditions such as Earth Pressure Balancing Types are fitted with Tail Seals to restrict water and grout flow. Existing grouting methods can cause problems by grout setting on the seals and to overcome this is costly.

The invention avoids this difficulty.

There is little or no waste and cheaper materials may be used in the method of the invention without the need for expensive accelerators or the need to monitor and adjust the proportions of the ingredients.

The invention is not limited to the embodiment shown. The bag may be water impermeable. The blocks may form a wall and not a ring. More than one bag may be present for each segment or block.

Claims

Agent's Ref: P00888GB

CLAIMS 1. A method of filling the space between the wall of a substrate and a lining which extends generally parallel to the wall and is made up of lining units arranged in side-by-side relation, each unit comprising a block having a throughhole, a flexible bag being connected to one face of the block, the method comprising placing the blocks alongside the wall with the bags facing the wall and then supplying via the throughhole sufficient filler material to expand the bags to fill the space.
2. A method according to Claim 1, wherein the bag is secured to the associated block by at least one releasable connector which retains the bag in a collapsed condition but which allows the bag to expand when the filler material is supplied therein.
3. A method according to Claim 2, wherein the bag is secured by sufficient connectors to hold the flexible bag generally flattened and parallel to the one face of the block.
4. A method according to Claim 2 or 3, wherein the bag is folded or pleated when in the flattened condition.
5. A method according to Claim 1,2 or 3, wherein the bag includes a spout inlet extending through the bore in the block for ingress of filler material into the bag.
6. A method according to any preceding Claim, wherein the bag is dimensioned so that the area thereof when full exceeds that of the block to which it is connected.
7. A method according to any preceding Claim, wherein the solid filler material is a self-setting composition.
8. A method according to Claim 7, wherein the composition comprises a hydraulically settable filler and water.
9. A method according to Claim 7 or 8, wherein the composition is substantially free of cement.
10. A method according to Claim 7 or 8, in which the composition is a cementitious, low density, cellular grout.
11. A method according to any of Claim 7 to 9, wherein the composition comprises fly ash and water.
12. A method according to any preceding Claim, wherein the bag is formed of a Geotextile material.
13. A method according to any of Claims 1 to 11, wherein the bag is formed of a water impenetrable material.
14. A method according to any preceding Claim, wherein the wall is a wall of an annulus excavated in the ground and the lining is a segmental lining of a tunnel.
15. A method according to any of Claims 1 to 13, wherein the wall is that of a sea defence wail or like structure.
16. A lining unit comprising a block of concrete or the like having two opposite major faces, a hole extending through the body from one face to the other, a bag of flexible material being secured to one face of the block by a releasable connector.
17. A unit according to Claim 16, wherein the bag is folded or pleated and is held generally flattened by the releasable connector.
18. A unit according to Claim 16 or 17, wherein the bag is formed of a Geotextile or water impenetrable material.
19. A tunnel comprising a tunnel ring in a bore with an annulus in between, the ring being built up of lining blocks arranged in side-by-side relation, each block having a throughhole, a flexible bag being connected to one face of the block, the bags facing the wall and being filled with sufficient filler material to expand the bags to fill the annulus.
20. A tunnel according to Claim 19, wherein the solid filler material is a self setting composition.
21. A tunnel according to Claim 20, wherein the composition comprises a hydraulically settable filler and water.
22. A tunnel according to any of Claims 19 to 21, wherein the composition is substantially free of cement.
23. A tunnel according to any of Claims 19 to 21, wherein the composition is a cementitious, low density, cellular grout.