GB2317405A

GB2317405A - Drivng a tubular member into the ground

Info

Publication number: GB2317405A
Application number: GB9619435A
Authority: GB
Inventors: James Martin O'callaghan
Original assignee: Murphy J & Sons Ltd
Current assignee: Murphy J & Sons Ltd
Priority date: 1996-09-18
Filing date: 1996-09-18
Publication date: 1998-03-25
Anticipated expiration: 2016-09-18
Also published as: GB2317405B; GB9619435D0

Abstract

An improved reinforced rubber sheet for use in a method of driving a tubular member into the ground, for example when constructing pedestrian underpasses. The method includes the steps of driving the member into the ground whilst deploying at least one sheet of material 8 between the tubular member and the adjacent ground. The sheet material remains substantially stationary with respect to the ground. The tubular member slides relative to the sheet during movement of the tubular member. The sheet is formed of a rubber material for example Neoprene, and is reinforced with a plurality of flexible elements, for example steel wires (see fig.4), which are embedded in the sheet. The upper side of the sheet engaging the ground may be roughened with ridges or chases. The belt may for example have a central core formed from Neoprene of one property, for example strength, and an outer cover of Neoprene with different properties, for example more resilience.

Description

DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO A METHOD OF, AND APPARATUS FOR, INSERTING TUBULAR MEMBERS INTO THE GROUND" THE PRESENT INVENTION relates to the insert ion of tubular members into the ground. More particularly, the invention relates to the insertion of tubular members into the ground in the construction of tunnels. A typical tunnel may be provided as a pedestrian or vehicular underpass.

When providing a tunnel, such as, for example, a pedestrian or vehicular underpass, it may be desirable to provide the tunnel beneath the existing buildings or beneath items such as an existing road or railway.

Consequently it is desirable to be able to establish a tunnel whilst making the minimum disturbance to the ground that surrounds the tunnel.

It has been proposed to create a tunnel, by driving a tubular member into the ground in a substantially horizontal direction whilst excavating earth from the interior of the tubular member.

It has been found that difficulties can arise when using a tunnelling technique of this type, since as the tubular member is driven forwards through the ground, it may tend to drag forwardly with it a layer of ground or earth immediately surrounding the tubular member.

It has been proposed previously (see GB A-1,313,575) to facilitate the advancement of a tunnel into the ground by providing a sheet of plastics material which is introduced between the tubular member that is to form the tunnel and the ground above the tubular member as the member is advanced into the ground. The sheet remains fixed relative to the ground and the tunnel slides relative to the sheet. Lubrication may be provided between the sheet and the tubular member.

The Specification GB-A-1,313,575 discloses a sheet of woven material coated with plastic on one side of about 2 millimetres thickness. Such sheets do tend to tear.

Specification GB-A-2,185,277 discloses an alternative arrangement in which a plurality of wire cables are used which are introduced between the tubular member and the ground. Part of each wire cable becomes embedded in the ground surrounding the tubular member, and the tubular member slides relative to the parts of the cables that contact the tubular member.

The individual cables may subsequently be individually removed from their position, and this subsequent removal of the cables does lead to some movement of the ground. Also, the cables can become tangled or snagged and require careful management.

The present invention seeks to provide an improved method of, and apparatus for, inserting a tubular member into the ground.

According to one aspect of this invention there is provided a method of driving a tubular member into the ground comprising the steps of driving the member into the ground whilst providing at least one sheet of material which is located between part of the member and the adjacent ground, the sheet of material being substantially stationary with respect to the ground, the tubular member sliding relative to the sheet during movement of the tubular member, the sheet being formed of a rubber material and being reinforced with a plurality of elongate flexible elements which are embedded in the sheet.

According to another aspect of this invention there is provided an apparatus for use when driving a tubular member into the ground, the apparatus comprising a shield adapted to be inserted into the ground in advance of the pipe, the shield having at least one roller means associated with a length of sheet and adapted to dispense the sheet to the exterior of the shield and thus to the exterior of the tubular member, the sheet comprising an element made of a rubber material and being reinforced with a plurality of elongate flexible elements which are embedded in the sheet.

The rubber material may be Neoprene and the elongate elements may comprise steel cables. The elongate elements may extend substantially axially of the sheet with a substantially uniform spacing.

The sheet may have a thickness of between 10 and 30 millimetres.

The upper surface of the sheet, which in use engages the ground, may be roughened, for example with transverse ridges or transverse chases.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which: FIGURE 1 is a perspective view of an apparatus for inserting a tubular member into the ground in accordance with the invention, FIGURE 2 is a cross-sectional view of the apparatus of Figure 1, FIGURE 3 is an enlarged view with part cut away, of a belt as used in the devices of Figures 1 and 2, and FIGURE 4 is an enlarged view with part cut away, of an alternative belt for using in the devices of Figures 1 and 2.

Referring initially to Figure 1, an apparatus for inserting a tubular member into the ground comprises a metal "shield" 1 in the form of a rectangular metal housing having a lower wall 2 and two side walls 3,4 and a top wall 5. The top wall 5 has a leading edge 6 which projects forwardly relatively to the base 2 and the side walls 3,4.

Adjacent the leading edge 6 of the top wall 5, two rollers 7 (see Figure 2) are provided. A length of belt 8 is associated with each roller, the belt 8 advancing towards the roller from within the shield 1, passing around the roller and then extending rearwardly across the top part 5 of the shield. While the drawings indicate that there are two rollers, it should be appreciated that a greater number of rollers may be used.

The interior of the shield is provided with abutments 9,10, which are associated with hydraulic rams 11,12. The shield is illustrated in conjunction with a tubular element 14 formed of concrete which is intended to form a tunnel.

It is to be appreciated that the shield, and the associated tubular element 14, are driven forwardly through the ground. Soil is excavated from the interior of the shield and passed out through the tubular element. The entire tubular element and the shield are advanced by hydraulic rams (not shown) and hydraulic rams 11,12 may be used to steer the shield 1.

As the shield advances, the belt 8 is paid out.

The part of the belt 8 that is located on top of the upper part of the shield firmly engages the ground and remains stationary relative to the ground. The under-surface of the belt 8, which is in contact with the upper part of the shield, and which is subsequently in contact with the upper part of the tubular element 14 made of concrete, may be lubricated so that there is a relatively free sliding effect between the upper part of the shield and the upper part of the tubular member 14 and the lower surface of the belt 8.

The belt 8 has a configuration which is illustrated more clearly in Figure 3. The belt 8 is of rectangular section and of substantially endless length. The belt 8 is formed of a rubber material such as, for example, Neoprene.

The belt may have a central core 20 formed of Neoprene of one property, e.g. strength, and an outer covering or sheath 21 formed of Neoprene with different properties, e.g. more resilience.

The central core 20 is reinforced with a plurality of longitudinally axially extending reinforcing elements 22. Each reinforcing element is preferably constituted by a length of steel wire rope or cable.

The overall thickness of the belt may be in the region of 10 millimetres to 30 millimetres, the optimum thickness being between 15 and 20 millimetres. The width of the belt may be conveniently between 1,300 millimetres and 1,000 millimetres, but belts of widths as small as 600 millimetres may occasionally be optimal.

The reinforcing elements may be located with close centres, the typical centre-to-centre distance being 10 millimetres for a thin belt and 15 millimetres for a thicker belt. Centre-to-centre distances of up to 25 millimetres may be appropriate. There may be up to 50 reinforcing elements in a typical belt having a width of 1,000 millimetres.

It is to be observed that the upper surface 23 of the belt is roughened, with a plurality of transverse ridges 24. These ridges are provided to given an enhanced grip on the ground above the tunnel.

Figure 4 shows an alternative configuration of the belt 8. The upper surface 23 of the belt is roughened with a plurality of transverse grooves or chases 25. The chases 25 may be moulded into the belt, or cut into the belt after it has been fabricated. The chases 25 give an enhanced grip on the ground above the tunnel. It is envisaged that both ridges and chases may be provided if desired.

It is to be appreciated that by using a reinforced belt made of Neoprene, and reinforced with steel wire ropes, the belt is very unlikely to tear or be damaged, since the belt has sufficient inherent strength to withstand the forces typically applied to it. Also, the belt is easy to manage without becoming twisted or tangled.

Claims

CLAIMS:

1. A method of driving a tubular member into the ground comprising the steps of driving the member into the ground whilst providing at least one sheet of material which is located between part of the member and the adjacent ground, the sheet of material being substantially stationary with respect to the ground, the tubular member sliding relative to the sheet during movement of the tubular member, the sheet being formed of a rubber material and being reinforced with a plurality of elongate flexible elements which are embedded in the sheet.

2. A method according to Claim 1 wherein the rubber material is Neoprene.

3. A method according to Claim 1 or 2 wherein the elongate elements comprise steel cables.

4. A method according to any one of Claims 1 to 3 wherein the elongate elements extend substantially axially of the sheet with a substantially uniform spacing.

5. A method according to any one of the preceding Claims wherein the sheet has a thickness of between 10 and 30 millimetres.

6. A method according to any one of the preceding Claims wherein the upper surface of the sheet which engages the ground is roughened.

7. A method according to any one of the preceding Claims wherein a shield is provided which is introduced into the ground in advance of the said tubular member, the shield having an open front end from which earth can be excavated, the shield having a roller at the upper part thereof, the roller guiding the said sheet from the interior of the shield to the exterior of the shield and thus to the exterior of the tubular member.

8. An apparatus for use when driving a tubular member into the ground, the apparatus comprising a shield adapted to be inserted into the ground in advance of the pipe, the shield having at least one roller means associated with a length of sheet and adapted to dispense the sheet to the exterior of the shield and thus to the exterior of the tubular member, the sheet comprising an element made of a rubber material and being reinforced with a plurality of elongate flexible elements which are embedded in the sheet.

9. An apparatus according to Claim 8 wherein the rubber material is Neoprene.

10. An apparatus according to Claim 8 or 9 wherein the elongate elements comprise steel cables.

11. An apparatus according to any one of Claims 8 to 10 wherein the elongate elements extend axially of the sheet with a substantially uniform spacing.

12. An apparatus according to any one of Claims 8 to 11 wherein the sheet has a thickness of between 10 and 30 millimetres.

13. An apparatus according to any one of Claims 8 to 12 wherein the upper surface of the sheet is roughened.

14. An apparatus according to Claim 13 wherein the upper surface of the sheet is roughened with transverse ridges.

15. An apparatus according to Claim 13 or 14 wherein the upper surface of the sheet is roughened with transverse chases.

16. A method of driving a tubular member into the ground, substantially as herein described with reference to the accompanying drawings.

17. An apparatus for use when driving a tubular member into the ground substantially as herein described with reference to and as shown in the accompanying drawings.

18. Any novel feature or combination of features disclosed herein.