GB2430684A

GB2430684A - Tunnelling device

Info

Publication number: GB2430684A
Application number: GB0520107A
Authority: GB
Inventors: John Phillip Doherty
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-10-03
Filing date: 2005-10-03
Publication date: 2007-04-04
Anticipated expiration: 2025-10-03
Also published as: GB0520107D0; GB2430684B

Abstract

A tunnelling device comprises a hollow body 12 having a longitudinal axis 31 and a cutter blade 14 mounted to a forward end of the body and rotatable about said axis, the hollow body having a frusto-conical fore 16 portion and a substantially cylindrical rear portion 18, the cutter blade 14 having a first portion 24 with a length substantially equal to the outer radius of the cylindrical rear portion and a second portion 26 having a length less than the outer radius of the cylindrical rear portion of the body. The tunnelling device may be steered by rotating the cutter blade 14 such that the longer portion 24 is moved to a desired rotational position, oscillating the cutter blade through an arc such that the longer portion thereof excavates a hollow and operating a jacking device to cause the tunnelling device to turn in the direction of the hollow.

Description

I

Tunnelling Device The present invention relates to a tunnelling device and particularly to a tunnelling device which is advanced through the ground by the application of pressure from a jacking means.

It is known to excavate a tunnel using a cutter apparatus or head which is advanced through the ground by pressure applied to the rear of the head by a hydraulic jack or ram. The pressure may be applied directly to the head or via on or more spacers positioned between the head and the ram. The cutter head typically comprises a hollow cylindrical body which is provided at its forward end with a rotatable cutter blade. In use, the blade breaks up the ground ahead of the of the cutter head. The broken up ground is typically removed by the recirculation of bentonite slurry through the cutter head. The slurry entrains the broken up ground and permits its removal from the tunnel. In order to circulate the slurry in the required manner, a relatively complex slurry supply system must be provided. For example, the cutter head, and any intermediate spacers, require internal supply and return pipe work, and the slurry supply means require adequate filtration means to remove material entrained within the slurry.

There also exist problems in the steering of conventional cutter heads.

According to a first aspect of the present invention there is provided tunnelling device comprising a hollow body having a longitudinal axis and a cutter blade mounted to a forward end of the body and rotatable about said axis, the hollow body having a frusto-conical fore portion and a substantially cylindrical rear portion, wherein the frusto-conical fore portion tapers from the cylindrical rear portion to a front face of the body, the cutter blade having a first portion with a length substantially equal to the outer radius of the cylindrical rear portion and a second portion having a length less than the outer radius of the cylindrical rear portion of the body.

In a preferred embodiment the front face of the body is substantially circular. In such an embodiment the second portion of the cutter blade may have a length substantially equal to the radius of the front face.

The front face is preferably provided with an aperture through which material dislodged by rotation of the cutter blade may pass for subsequent removal. The body may be provided with an internal conduit aligned with the aperture through which the material may be conveyed. The front face may be provided with a plurality of apertures aligned with the conduit.

According to a second aspect of the present invention there is provided a tunnelling system including a tunnelling device comprising a hollow body having a longitudinal axis and a cutter blade mounted to a forward end of the body and rotatable about said axis, a jacking unit operable to advance the tunnelling device, a power source operable to rotate the cutter blade and a vacuum source operable to remove material excavated by the tunnelling device.

According to a third aspect of the present invention there is provided a method of tunnelling, the method comprising the steps of: providing a tunnelling device comprising a hollow body having a longitudinal axis and a cutter blade mounted to a forward end of the body and rotatable about said axis, the hollow body having a frusto-conical fore portion and a substantially cylindrical rear portion, wherein the frusto-conical fore portion tapers from the cylindrical rear portion to a front face of the body, the cutter blade having a first portion with a length substantially equal to the outer radius of the cylindrical rear portion and a second portion having a length less than the outer radius of the cylindrical rear portion of the body; providing a power source operable to rotate the cutter blade; providing a jacking device having an extensible ram; providing a vacuum source in communication with the tunnelling device; associating the tunnelling device with the jacking device; operating the power source to rotate the cutter blade; operating the jacking device to contact and subsequently move the tunnelling device in a tunnelling direction; and operating the vacuum source to remove material cut bay the cutter blade.

The method may include the step of steering the tunnelling device, which step includes the further steps of: rotating the cutter blade such that the longer portion thereof is moved to a desired rotational position; oscillating the cutter blade through an arc such that the longer portion thereof excavates a hollow; and operating the jacking device to cause the tunnelling device to turn in the direction of the hollow.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a cross-sectional view of a cutter apparatus according to the present invention; Figures 2 and 3 show front views of a cutter apparatus with differing cutter blade configurations; and Figure 4 shows a representation of a tunnelling system incorporating the cutter apparatus of figures 1 to 3.

Referring firstly to figures 1 and 2 there is shown a cutter apparatus generally designated 10. The apparatus 10 comprises a substantially hollow body 12 and a cutter 14. The body 12 comprises a tapered fore portion 16 and a cylindrical after portion 18.

The tapered portion 16 extends between the after portion and a circular forward face 20 of the body 12. The cutter 14 comprises a cutting blade 22 having first and second arms 24,26. The blade 22 is mounted to an axle 28 which passes through an aperture 30 provided in the forward face 20 of the body 12. The axle 28 is carried by an appropriately configured bearing (not shown) such that the axle 28 is rotatable about the longitudinal axis 31 of the apparatus 10. The axle 28 includes a drive coupling 32 which enables the cutter 14 to be connected to an appropriately configured drive means (not shown).

The forward face 20 of the body 12 is provided with an aperture 34 which is aligned with a tube 36 provided within the body 12. The aperture 34 and tube 36 are provided for the vacuum removal of material cut by the cutting blade 22 as described in greater detail below. While one aperture 34 is shown, there may be provided a plurality of apertures which are positioned within the boundary of the end of the tube 36 adjacent the forward face 20.

It will be appreciated that that the arms 24,26 of the cutting blade 20 are of unequal length. The shorter of the arms 26 has a length substantially equal to the radius of the forward face 20. The longer of the arms 24 has a length substantially equal to the radius of the cylindrical after portion 18 of the body and as such projects beyond the forward face 20.

Operation of the apparatus 10 will now be described. Figure 4 illustrates the formation of a tunnel 40 utilising a cutter apparatus 10 of the type described. The tunnel 40 extends from a shaft 42 which has been sunk into the ground 44 through which the tunnel is to extend. Within the shaft 42 there is provided a jacking unit 46 including an extensible ram 48. In figure 4 there are shown a number of spacer elements 50 positioned between the jacking unit 46 and the cutter apparatus 10. The spacers 50 each comprise a cylindrical body having a diameter substantially equal to that of the after portion 18 of the body 12. Each spacer 50 further includes an internal tube 36 which is of the same diameter as the tube 36 of the cutter apparatus 10. There is also provided a power source 52 for the cutter blade drive mechanism and a vacuum source 54 connected to the tubes 36 of the cutter apparatus 10 and spacers 50.

In order to commence a tunnelling operation, the ram 48 of the jacking unit 46 is retracted and the cutter apparatus 10 lowered into the shaft 42 and onto a launch bed 56 of the jacking unit 46. The power and vacuum sources 52,54 are connected to the apparatus 10 and the ram 48 extended so as to advance the cutter apparatus 10 towards the wall of the shaft 42. Upon contact with the shaft wall the drive mechanism is operated so as to rotate the cutter blade 22. Operation of the vacuum source 54 is also commenced. Continued pressure form the ram 48 advances the apparatus 10 into the ground 44, while the rotation of the cutter blade 22 causes the break up of material ahead of the apparatus. The broken up material is swept by the arms 24 towards the aperture or apertures 34 in the forward face 20. The material then passes into the internal tube 36 of the apparatus 10 whereupon it is removed by the vacuum source. It will be appreciated that the vacuum source 54 directs the material to a suitably configured container or the like remote from the shaft 42.

Once the apparatus 10 has been advanced to the full extent of the ram 48, the ram 48 is retracted and the power and vacuum connections to the apparatus are disconnected. A spacer 50 is then placed on the launch bed 56 and the power and vacuum connections re-established with the cutter apparatus 10 through the spacer 50. The ram 48 is then extended as before to advance the cutter apparatus 10 further into the ground 44. The cutter blade 22 is rotated as before, and material is removed by the vacuum source 54.

Additional spacers 50 are introduced in the manner described above to move the cutter apparatus 10 and excavate the tunnel 40.

The provision of the tapered fore portion 16 and the differing lengths of the cutter arms 24,26 assist with the steering of the cutter apparatus 10 during tunnelling. During normal tunnelling operations the cutter blade is continually rotated in a unidirectional manner, either clockwise or anticlockwise. This results in the cutter apparatus following a substantially straight path. In order to effect a turn the cutter blade 22 is oscillated backwards and forwards over a predetermined arc such that the longer of the arms 24 excavates a hollow to one side of the cutter apparatus. As the longer of the arms 24 during such an operation no longer fully rotates, it will be understood that the ground 42 bears against the part of the tapered portion 16 which is not within the hollow. The continued pressure exerted by the ram 48 on the cutter apparatus 10, and any intermediate spacers 50, causes the cutter apparatus to turn towards the hollow and thereby alter the excavation path of the cutter apparatus 10. It will be appreciated that the direction and angle through which the cutter apparatus 10 may be caused to turn is dependent upon such factors as, for example, the initial position of the longer cutting arm 24 when oscillation is commenced, the arc length through which the arm 24 is oscillated, and the portion of the stroke length of the ram 48 over which the oscillation of the cutter blade 22 is undertaken.

The embodiment of the cutter described with reference to figures 1 and 2 is provided with a blade 22 having two arms 24,26 which are aligned along a common axis. It will be understood that other blade configurations may be employed. Figure 3 illustrates a blade 22 having three arms comprising a longer arm 24 and two shorter arms 26.

Claims

Claims 1. A tunnelling device comprising a hollow body having a

longitudinal axis and a cutter blade mounted to a forward end of the body and rotatable about said axis, the hollow body having a frusto-conical fore portion and a substantially cylindrical rear portion, wherein the frusto- conical fore portion tapers from the cylindrical rear portion to a front face of the body, the cutter blade having a first portion with a length substantially equal to the outer radius of the cylindrical rear portion and a second portion having a length less than the outer radius of the cylindrical rear portion of the body.
2. A tunnelling device as claimed in claim I wherein the front face of the body is substantially circular.
3. A tunnelling device as claimed in claim 2 wherein the second portion of the cutter blade has a length substantially equal to the radius of the front face.
4. A tunnelling device as claimed in any of claims 1 to 3 wherein the front face is provided with an aperture through which material dislodged by rotation of the cutter blade can pass for subsequent removal.
5. A tunnelling device as claimed in claim 4 wherein the body is provided with an internal conduit aligned with the aperture through which the material can be conveyed.
6. A tunnelling device as claimed in claim 4 or claim 5 wherein the front face is provided with a plurality of apertures aligned with the conduit.
7. A tunnelling device as claimed in any preceding claim therein the cutter blade is provided with two blade portions aligned along a common axis.
8. A tunnelling device as claimed in any of claims I to 6 wherein the cutter blade is provided with a plurality of blade portions aligned along axes which intersect with the longitudinal axis of the body.
9. A tunnelling device as claimed in claim 8 wherein one of said plurality of blade portions has a length substantially equal to the outer radius of the cylindrical rear portion and the remainder of said plurality of blade portions have a length less than the outer radius of the cylindrical rear portion of the body.
10. A method of tunnelling, the method comprising the steps of: providing a tunnelling device comprising a hollow body having a longitudinal axis and a cutter blade mounted to a forward end of the body and rotatable about said axis, the hollow body having a frusto-conical fore portion and a substantially cylindrical rear portion, wherein the frusto-conical fore portion tapers from the cylindrical rear portion to a front face of the body, the cutter blade having a first portion with a length substantially equal to the outer radius of the cylindrical rear portion and a second portion having a length less than the outer radius of the cylindrical rear portion of the body; providing a power source operable to rotate the cutter blade; providing a jacking device having an extensible ram; providing a vacuum source in communication with the tunnelling device; associating the tunnelling device with the jacking device; operating the power source to rotate the cutter blade; operating the jacking device to contact and subsequently move the tunnelling device in a tunnelling direction; and operating the vacuum source to remove material cut bay the cutter blade.
11. A method as claimed in claim 10 wherein the method includes the step of steering the tunnelling device, which step includes the further steps of: rotating the cutter blade such that the longer portion thereof is moved to a desired rotational position; oscillating the cutter blade through an arc such that the longer portion thereof excavates a hollow; and operating the jacking device to cause the tunnelling device to turn in the direction of the hollow.
12. A tunnelling system including a tunnelling device comprising a hollow body having a longitudinal axis and a cutter blade mounted to a forward end of the body and rotatable about said axis, a jacking unit operable to advance the tunnelling device, a power source operable to rotate the cutter blade and a vacuum source operable to remove material excavated by the tunnelling device.