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(11) | EP 0 122 103 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Machine for boring tunnels |
| (57) A machine for boring tunnels comprises concentric outer and inner sleeves (2, 4)
between the forward extents of which is defined an annular housing (6). A spiral auger
(8) extends axially through the inner sleeve (4) and carries at its forward end a
primary cutting head (10), while an annular secondary cutting head (14) is mounted
in the annular housing (6) and is rotatable about the central axis of the sleeves
(2, 4) on rotation of the auger (8). A series of steering plates (20) are spaced circumferentially
about the forward extent of the outer sleeve (2) and are pivotal outwardly of said
sleeve (2) on actuation of associated control members (22) to control the direction
of movement of the machine on thrusting of said machine through the ground by an associated
thrust mechanism reacting against the rear ends of the sleeves (2, 4) and providing
power for rotating the auger (8) and associated cutting head (10,14). |
[0001] This invention relates to machines for boring tunnels, and more particularly to such machines incorporating powered augers for removing material to form the tunnels.
[0002] There are many long-established methods of forming underground tunnels, particularly of small diameters, of which auger boring has certain distinct advantages. Auger boring utilises an auger boring machine mounted on, to be movable along, a fixed length of track whereby said machine can apply a forward thrust to a steel sleeve in which is mounted a rotatable auger carrying a cutting head. The cutting head removes material ahead of and around the front of the sleeve, the sleeve, auger and cutting head being moved forwards in unison the length of the track by the auger boring machine. After this first stage has beem completed, the auger boring machine is returned back along the track, a second steel sleeve is coupled to the rear of said first sleeve, an auger extension piece is coupled to said first-mentioned auger and the procedure is repeated.
[0003] Upon completion of the tunnel, the extended auger and cutting head are withdrawn from inside the coupled sleeves and a lining is placed in said sleeves, which sleeves are themselves left in the ground.
[0004] Such a method of tunnelling is comparatively fast, which is particularly useful when working in built-up areas, under roads or under railway tracks where speed restrictions cannot be maintained indefinately. A consequential advantage of speed of tunnelling is that the overall cost is reduced considerably, while further advantages of auger boring are that skilled labour is not as essential as in other methods, while danger to personnel is significantly reduced compared with other methods, in that there is no need for men to be present in the hazardous environment of the tunnel.
[0005] However, current auger boring techniques involve certain major disadvantages, particularly in that they are inaccurate and cannot therefore be used on the _.majority of sewage schemes where constant rates of fall have to be maintained. This inaccuracy stems from the clockwise rotation of the auger tending to move the sleeve downwards and to the right relative to the desired line of the tunnel. Further, it is necessary for the cutting head to overcut material from the front of the sleeve to enable said sleeve to be moved readily along the bore formed by the cutting head. This overcutting is achieved by attaching wing cutters to the main bit, but the tendency of such cutters is to remove more material from the bottom and right hand side of the bore then elsewhere, thus exaggerating steering problems.
[0006] The nature of the cutting heads of existing auger boring systems is such that they cannot drill through rocks or other solid materials, the machine coming to a halt when the cutting head hits anything hard.
[0007] It would be desirable to be able to provide an auger boring machine which could be steered more accurately than heretofore and which could cut through a wider range of materials than heretofore.
[0008] According to the present invention there is provided a machine for boring tunnels, said machine including a cylindrical outer sleeve the rear end of which is adapted for engagement by a thrust mechanism to urge the sleeve through material to be bored, an inner sleeve concentrically located in the outer sleeve to define, together with said outer sleeve, an annular housing between the forward extents of said inner and outer sleeves, and a spiral auger extending axially through the inner sleeve and carrying at its forward end a primary cutting head projecting forwardly of said sleeves, the machine further including an annular secondary cutting head mounted in, to project forwardly from said housing, said secondary cutting head co-operating with the auger such that rotation of said auger causes bodily rotation of the secondary cutting head in the annular housing about the central longitudinal axis of the sleeves, and a plurality of steering plates spaced about the circumference of the forward end extent of the outer sleeve to be pivotal from inoperative positions substantially flush with the outer surface of the outer sleeve to operative positions projecting angularly outwardly and rearwardly of said sleeve to control the direction of movement of the machine on thrusting of said machine through material to be bored.
[0009] Conveniently the housing contains an annular roller bearing track on which the annular secondary cutting head rotates, drive from the auger to the secondary cutting head being transmitted through interengaging means on said auger and cutting head.
[0010] Preferably there are four steering plates equally spaced about the circumference of the outer sleeve each pivotal about an associated forward axis extending substantially circumferentially of said outer sleeve.
[0011] Each steering plate may be actuated by an associated control member, conveniently a hydraulic ram, contained within the annular housing adjacent the steering plate.
[0012] The machine preferably includes control means for actuating said control members in dependence upon the position of the outer sleeve relative to the desired position of said sleeve.
[0013] Said control means conveniently comprises a fixed laser located to direct a laser beam through a passageway in the machine and onto a target in the annular housing, the position of the beam on the target being monitored by a television camera in said housing, and the steering plate control members being actuated such as to maintain the laser beam at a predetermined position on the target associated with the desired line of travel of the machine.
[0014] By way of example only, an embodiment of the invention will now be described in greater detail with reference to the accompanying drawings of which:
Fig. 1 is a schematic longitudinal section through the forward regions of a machine according to the invention, and
Fig. 2 is a front view of the machine of Fig. 1.
[0015] The illustrated machine is normally used in conjunction with a thrust mechanism (not shown) which is mounted on, to be movable along, a fixed length of track, the track reacting against fixed thrust blocks. The mechanism typically provides 300 tonnes thrust for application to the machine of the invention through a pusher ring forming the front end of the thrust mechanism and against which the rear end of the machine abuts, said mechanism also typically develping.60,000 pounds torque for application to the auger of the machine as will be detailed below.
[0016] Referring to the drawings, the machine comprises a cylindrical outer steel sleeve or tube 2 and a concentric inner steel sleeve 4 the illustrated forward extent of which may be of trough-shape i.e. substantially semi-circular in transverse section. Thus an annular housing 6 is defined between the forward extents of the sleeves 2,4.
[0017] A spiral auger 8 of maximum diameter just less than the inner diameter of the sleeve 4 extends axially of, the length of, the machine, the leading end of the auger 8 carrying a primary cutting head 10 which projects slightly forwards of the sleeves 2,4. The rear end of the auger 8 is adapted for coupling to the drive from the thrust mechanism.
[0018] An annular roller bearing track 12 mounted in the housing 6 supports a secondary cutter in the form of an annular trepanning head 14 best seen in Fig. 2 and rotatable bodily in the track 12 about the central longitudinal axis of the sleeves 2,4. Drive to the head 14 is transmitted from the auger 8 through an interlocking clutch comprising co-operating flanges 16, 18 on the auger 8 and head 14 respectively. The cutters of the head 14 project forwardly of the sleeves 2,4 and slightly radially outwardly of the sleeve 2.
[0019] Four equi-spaced steering plates 20 are provided around the circumference of the forward end extent of outer sleeve 2, each plate 20 being pivotal about its front, circumferentially extending edge between an inoperative position substantially flush with the outer surface of the outer sleeve 2 and an operative position projecting angularly rearwardly and outwardly from said sleeve 2 as seen in Fig. 1.
[0020] Pivotal movement of the steering plates 20 is achieved through associated hydraulic rams 22 mounted in the annular housing 6 one adjacent each plate 20.
[0021] The steering plates are to be pivoted with a view to maintaining the direction of movement of the machine, when in use, on a desired and predetermined line. Control means for determining the position of the machine at any given moment and, if necessary, redirecting the machine back onto the desired line are provided in the form of a laser fixed relative to the machine and positioned to direct a laser beam 24 parallel with the central axis of the machine through the annular gap between the sleeves 2,4 and onto a target 26 fixed in the annular housing 6.
[0022] A television camera 28 mounted in the housing 6 constantly monitors the position of the beam 24 on the target 26 and transmits a signal back to a control centre indicative of whether or not the beam is impinging upon the target at a position associated with the desired line of movement of the machine. This signal is used to activate, if necessary, one or more of the rams 22 which in turn pivot the associated steering plate or plates 20 to redirect the machine back to its desired line, determined by the beam 24 hitting the target 26 at the desired point.
[0023] In use of the above-detailed machine to bore an underground tunnel, the aforementioned thrust mechanism is located at the rear end of the fixed length of track located adjacent the face to be bored, the machine is positioned on the track with the rear end of the sleeves 2,4 abutting the pusher ring of the thrust mechanism and the auger 8 is coupled to the rotary drive of the thrust mechanism. In this position the cutting head 10 engages the face to be bored and the laser beam 24 is incident upon the desired area of the target 26.
[0024] The machine is thrust forwards along the track by the thrust mechanism with the rotating heads 10,14 cutting through the ground ahead of the machine whereby a tunnel is formed, the material cut by the heads 10,14 being fed by the spiral auger 8 rearwards through the machine to an outlet from the machine adjacent the rear end thereof.
[0025] Throughout the boring operation, the beam 24 from the fixed laser is constantly impinging upon the target 26 and, if the machine deviates from the desired line of the tunnel, the target 26 is moved relative to the beam and this relative movement is detected by the camera 28. The signal received at the control centre from the camera indicates that redirection of the machine is required and this results in appropriate actuation of one or more of the hydraulic rams 22 to pivot the associated steering plate or plates 20 outwardly such as to steer the machine back onto its desired line of travel.
[0026] Once the machine has been moved forward as far as possible by the thrust mechanism - i.e. said mechanism has reached the front of the track - the boring operation is stopped and the thrust mechanism is reversed back to the rear end of the track. A length of tubing, conveniently comprising inner and outer sleeves, is secured to the rear end of the machine to form axial extensions of the sleeves 2,4, an auger extension is secured to the auger 8, the thrust mechanism is abutted against the rear end of the length of tubing and the auger extension is connected to the powered drive of said thrust mechanism. The thrust mechanism is then moved forwards again along the track whereby the machine and said length of tubing are driven through the ground substantially as described above to extend the tunnel, the head 14 again overcutting the tunnel to allow ready movement of the machine therealong, and the steering plates 20 being actuated by way of the laser and beam to maintain the machine on the correct line.
[0027] This procedure is repeated until the tunnel is complete, when the machine, auger 8 and auger extensions are withdrawn from the tunnel leaving the lengths of tubing in.position to define the tunnel.
[0028] The precise nature of the lengths of tubing used to constitute the tunnel can be chosen to suit particular requirements - said lengths may be of, for example,steel and/or concrete, while the inner portion may or may not be removed subsequent to boring being completed.
[0029] The provision of a boring machine as detailed above ensures accurate directional control to standards usually associated with hand mining methods, while the provision of the trepanning cutting head 14,overcutting the bore of the tunnel slightly,greatly facilitates thrusting of the machine and lengths of tubing along the bore. The spiral auger 8 serves to feed material cut from the face along and out of the machine while the nature of the cutting heads 10,14 is such as to enable penetration of rocks and boulders that known machines could not tackle.
1. A machine for boring tunnels, the machine including a cylindrical outer sleeve
(2) the rear end of which is adapted for engagement by a thrust mechanism to urge
the material through material to be bored, and characterised by an inner sleeve (4)
concentrically located in the outer sleeve (2) to define, together with said outer
sleeve (2), an annular housing (6) between the forward extents of said inner and outer
sleeves (2,4), and a spiral auger (8) extending axially through the inner sleeve (4)
and carrying at its forward end a primary cutting head (10) projecting forwardly of
said sleeves (2,4), the machine being further characterised by an annular secondary
cutting head (14) mounted in, to project forwardly from said housing (6), said secondary
cutting head (14) co-operating with the auger (8) such that rotation of said auger
(8) causes bodily rotation of the secondary cutting head (14) in the annular housing
(6) about the central longitudinal axis of the sleeves (2,4), and a plurality of steering
plates (20) spaced about the circumference of the forward end extent of the outer
sleeve (2) to be pivotal from inoperative positions substantially flush with the outer
surface of the outer sleeve (2) to operative positions projecting angularly outwardly
and rearwardly of said sleeve to control the direction of movement of the machine
on thrusting of said machine through material to be bored.
2. A machine as claimed in claim 1 in which the housing (6) contains an annular roller
bearing track (12) on which the annular secondary cutting head (14) rotates, drive
from the auger (8) to the secondary cutting head (14) being transmitted through interengaging
clutch means (16,18) on said auger (8) and cutting head (14).
3. A machine as claimed in claim 1 or claim 2 and including four steering plates (20)
equally spaced about the circumference of the outer sleeve (2) each pivotal about
an associated forward axis extending substantially circumferentially of said outer
sleeve (2).
4. A machine as claimed in any one of claims 1 to 3 in which each steering plate (20)
is actuated by an associated control member (22) contained within the annular housing
(6) adjacent the steering plate (20).
5. A machine as claimed in claim 4 in which the control members each comprise a hydraulic
ram (22).
6. A machine as claimed in claim 4 or claim 5 and including control means (24,26,28)
for actuating said control members (22) in dependence upon the position of the outer
sleeve (2) relative to the desired position of said sleeve (2).
7. A machine as claimed in claim 6 in which the control means comprises a fixed laser
located to direct a laser beam (24) through a passageway in the machine and onto a
target (26) in the annular housing (6), the position of the beam on the target (26)
being monitored by a television camera (28) in said housing (6) and the steering plate
control members (22) being actuated such as to maintain the laser beam (24) at a predetermined
position on the target associated with the desired line of travel of the machine.