GB2091316A - Tunnelling - Google Patents

Abstract

A hydraulic shield tunnelling method comprising the steps of; causing a liquid to act on the ground at a face under a pressure substantially equal to the pressure of underground water at the face, during excavation of a tunnel, and controlling at least one of a speed of thrusting a shield body, a rotating speed of a cutter head and the openings of cutter slits. A hydraulic shield tunnelling machine embodying the tunnelling method comprises a device for controlling operation of at least one of a shield-body thrusting device 66, a cutter-head driving device 32 and a device for adjusting the opening of respective cutter slits 52, according to a distance of sliding of the cutter head 24 or a level of earth pressure at the face 100. <IMAGE>

Description

SPECIFICATION Hydraulic shield tunnelling method and machine This invention relates to a hydraulic shield tunnelling method and machine, and more particularly to a method for excavating a tunnel while preventing falls of the face, and a machine therefor.

Sludge-pressure type shield tunnelling processes are well known. The sludge pressure type shield tunnelling process includes the steps of; excavating a tunnel while stabilizing the ground with compressed sludge; introducing the sludge excavated through cutter slits into a sludge chamber; and transporting sludge from the sludge chamber through a sludge pipe to a spot outside the tunnel. The speed of the tunnelling machine is controlled according to the amount of sludge discharged outside the tunnel.

The amount of sludge discharged is determined by measuring the density of the soil, the specific gravity of sludge flowing through the sludge pipe to a spot outside the tunnel, and the flow rate of sludge passing through the sludge pipe, by feeding the measurements into a computer for calculation.

According to an amount of discharged sludge thus calculated the speed of the tunnelling machine has been automatically controlled or manually adjusted. However, calculation of the density of the soil is performed by applying to an equation a value assumed on the basis of a study of the nature of the soil which has been made beforehand, as a result of which an error is necessarily incurred. Besides this error in the density of the soil, an error in the flow rate of the sludge as well as in the specific gravity thereof are also incurred resulting in a large aggregate error in the amount of sludge being discharged. Such a large error directly influences the speed of the tunnelling machine.Should a balance between the amount of soil and sand excavated and the tunnelling speed be lost, the stability of the ground would be impaired, thus leading to subsidence or raising of the land surface above the tunnel.

It is an object of the present invention to provide a hydraulic shield tunnelling method and a machine therefor, wherein excavation of a tunnel or the like is facilitated without causing subsidence or raising of the land surface during the tunnelling work at the face.

According to one aspect of the present invention a hydraulic shield tunnelling method comprises causing a liquid to act on the ground at a face under a pressure substantially equal to a pressure of underground water at the face during the tunnelling; and pressing a cutter head against the ground at the face under a pressure larger than an active earth pressure but smaller than a passive earth pressure, by controlling at least one of rotation of said cutter head, speed of thrusting a shield body and the openings of cutter slits thereby preventing falls of the face.

The hydraulic shield tunnelling machine according to a second aspect of the present invention comprises a shield body; a partition wall located internally of said shield body; a cutter head rotatably supported by said partition wall in a manner to effect a linear movement and having a plurality of slits; a device for supplying into a portion at the front of said partition wall a liquid under a pressure substantially equal to the pressure of underground water at the face; a device for pressing said cutter head against the ground at the face under a pressure larger than the active earth pressure but smaller than the passive earth pressure; a device for thrusting the shield body; a cutter head driving device; a device for adjusting the openings cutter slits; a device for detecting a distance of sliding movement of said cutter head; and a device for controlling operation of at least one of said shield-body thrusting device, said cutter-head driving device and said device for adjusting the openings of cutter slits.

The hydraulic shield tunnelling machine in the modified form is characterized by a shield body, a partition wall provided internally of the shield body, a cutter head supported on the partition wall rotatably and in a manner to effect a linear movement, a device for supplying a liquid under a pressure substantially equal to a pressure of underground water at the face into a portion at the front of the partition wall, a shield-body thrusting device, a cutter-head driving device, a device for adjusting openings of cutter slits, a device for detecting a distance of sliding movement of the cutter head, and a device for operating at least one of the shield-body thrusting device, the cutterhead driving device and the cutter-slit-opening adjusting device, according to a distance of sliding movement of the cutter head thus detected.

The invention may be better understood from the following description by way of examples, with reference to Figures 1 to 6 of the accompanying drawings.

Fig. 1 is a schematic cross sectional view of a hydraulic shield tunnelling machine according to a first embodiment of the invention; Fig. 2 is a longitudinal cross sectional view of a cutter head; Fig. 3 is a transverse cross sectional view taken along the line 3-3 of Fig. 2; Fig. 4 is a schematic cross sectional view of a hydraulic shield tunnelling machine according to a second embodiment of the present invention; Fig. 5 is a schematic longitudinal cross sectional view of the tunnelling machine according to a third embodiment; and Fig. 6 is a schematic cross sectional view of the tunnelling machine according to a fourth embodiment.

Referring first to Fig. 1, a hydraulic shield tunnelling machine is generally shown at a reference numeral 10. The tunnelling machine 10 includes a shield body 12 and a partition wall 14 located internally across the front portion of the shield body. The shield body 12 is divided by the partition wall 14 into a liquid pressure chamber 1 6 and an atmospheric pressure chamber 18. The partition wall 14 is provided with an inlet and outlet for a pressurized fluid, into which are fitted pressurized fluid pipes 20 and 22 for supplying the pressurized fluid such as fresh water or sludge into the pressurized liquid chamber 1 6 and discharging therefrom, respectively.

A cutter head 24 is provided in the pressurized liquid chamber 16, and a drive shaft 26 is attached to the cutter head 24. The drive shaft 26 is carried by a bearing 27, which in turn is attached to the partition wall 14, and extends into a gear box 28 attached to the back side of the partition wall 14. In the gear box 28, a main gear 30 is in mesh with a gear 34 mounted on a shaft 33 which extends into the gear box from a hydraulically driven motor 32 attached to the external wall of the gear box, so that a drive force of the hydraulic motor 32 will be transmitted to the drive shaft 26, for rotating same.

The drive shaft 26 further extends through another bearing 35 attached to the gear box 28 and terminates in a housing 36 attached to the rear wall of the gear box 28. In the housing 36, a load detector 38 for detecting an earth pressure at the face is supported by a rod 40 in engagement with the rear end of the drive shaft 26. The load detector 38 consists of load cells. A doubleacting piston-cylinder device 42 is attached to the rear wall of the housing 36, with a piston rod 44 extending through a longitudinal central hollow portion 60 running through the rod 40, the load detector 38 and the drive shaft 26 and projecting from the front end of the drive shaft 26, as best seen in Fig. 2.

Referring to Fig. 2, the cutter head 24 includes a face 46 attached to the front end of the drive shaft 26. The face 46 is provided with cutter slits 48 radially spaced apart from one another. The cutter head 24 also includes a cutter disc 50 slidably mounted on the drive shaft 26 at the rear of the face 46. A plurality of cutter bits 52 are attached to the cutter disc 50 in register with cutter slits 48 in the face 46, so that the bits 52 will project or retract from the cutter slits 48 when the cutter disc 50 is slidingly displaced on the drive shaft 26.

Two or more rods 54 are attached to the cutter disc 50, as seen in Fig. 2. These rods extend from the cutter disc 50 through longitudinal hollow portions or passages 56 to project from the front end of the drive shaft 26, and attached at the other end thereof to a coupling member 58. That is to say, one end of each respective rod 54 is fixedly screwed in the cutter disc, and the other end of the respective rod is coupled to the coupling member 58.

the other end of the piston rod 44 extending ahead of the drive shaft through the hollow central passage 60 provided in the drive shaft 26 is attached to the coupling member 58. The cutter disc 50 is thus slidingly moved on the drive shaft 26 by the force which is transmitted thereto from the double-acting piston-cylinder device 42 serving as a drive source via the piston rod 44, the coupling member 58 and the rods 54.

A flange 62 projects radially inwardly from the inner wall of the shield body 12. Shield-body thrusting jacks 66 are disposed between the flange and segments 64 assembled along the inner wall of the shield body 12 in the rear portion of the shield body. The shieid-body thrusting jacks 66 thrust the shield body 12 ahead of the tunnelling machine (to the left as viewed in Fig. 1) by a reaction force received on the end faces of the segments 64.

The hydraulically driven motor 32 for rotating the drive shaft 26, the piston cylinder device 42 for moving the cutter disc 50 slidingly for adjustment of the extent each bit projects from each respective slit 48, namely the opening of respective cutter slit 48, and jacks 66 are connected to pumps 68, 70 and 72 in which an amount of pressurized oil being supplied is variable (hereinafter referred to as variable pumps), respectively. These variable pumps are operated by a pressurized oil power unit 74. These variable pumps 68, 70 and 72 have control arms 76, 78 and 80 for controlling an amount of pressurized oil being supplied, respectively.The ends of control arms 76, 78 and 80 are pivotally secured to the piston rods of double-acting pistoncylinder devices 82, 84 and 86, respectively, so that these control arms are pivotally moved by the strokes of these piston rods, thereby controlling an amount of pressurized oil being supplied from respective variable pump. The piston-cylinder devices 82, 84 and 86 communicate with a pump 94 via power-feedback type servo-valves 88, 90 and 92, respectively. These servo-valves 88, 90 and 92 are of a known type, and hence no description is given here. The differential voltage transforming portions of respective servo-valves 88, 90 and 92 are connected via electric lines to an electric control device 96, so that respective servo-valves are controlled by electric signals.The electric control device 96 is connected via an electric line to the load detector 38, so as to receive electric signals from the load detector.

In excavating a tunnel, sludge is transported through the pressurized fluid pipe 20 into the liquid pressure chamber 16, and discharged from the liquid chamber 1 6 through the pressurized fluid pipe 22 to a place outside the tunnel. A pressure for transporting sludge through the pressurized fluid pipe 20 into the liquid pressure chamber 1 6 is so determined that a pressure of sludge in the liquid pressure chamber 1 6 is substantially equal to a pressure of underground water at the face 1 00. The cutter head 24 is rotated by a drive force transmitted from the hydraulically driven motor 32 via the gear 34, reduction gear 30 meshing with the gear 34 and the drive shaft 26. Then, the shield body 12 is thrust forward by the jacks 66, whereas the cutter head 24 is pressed against the ground at the face under a pressure larger than the active earth pressure but smaller than the passive earth pressure. The tunnelling machine 10 is advanced, while preventing collapse of the tunnel, by the pressurized liquid against the pressure of underground water at the face and by the pressure of the cutter head 24 against the ground at the face.

During tunnelling the pressure of the cutter head 24 against the ground at the face is caused to act on the cutter head as a reaction force of the ground at the face. The earth pressure, which is the reaction force received by the cutter head, is detected via the drive shaft 26 by the load detector 38 as a horizontal thrust load. Stated otherwise the load detector 28 detects whether or not the cutter head is pressed against the ground at the face under pressure larger than the active earth pressure but smaller than the passive earth pressure. For example, when the pressure of the cutter head becomes smaller than the active earth pressure, the electric control device 96 senses the above state by the signals from the load detector 38 and transmits signals to one of the servovalves 88, 90 and 92.For example, if signals are transmitted to the servo-valve 88, the piston cylinder device 82 is operated to pivotally move the control arm 76 so as to control a drive force of the hydraulically driven motor 32, so that rotation of the cutter head 24 will be decelerated.

Consequently, a reduced amount of soil is excavated. Since the speed of thrusting the shield body 1 2 is constant the pressure of the cutter head meets with a high earth pressure at the face.

When the servo-valve 90 is actuated, the control arm 78 is pivoted to control a thrust of the jacks 66 in a direction to accelerate a speed of thrusting the shield body, whereby the pressure against the ground at the face, of the cutter head 24 is increased.

Where the servo-valve 92 is controlled, the piston-cylinder device 42 is controlled, so that the piston rod 44 is moved to the right as viewed in Fig. 1, thereby displacing the cutting disc 50 to the right (as viewed in Fig. 2) in the manner shown in Fig. 3. As a result, the cutter bits 52 attached to the cutter disc 50 are put into slits 48 in the face 46 to assume the retracted position shown by a dotted line in Fig. 3. The extent to which a respective bit projects is thus controlled, and hence the opening of a respective cutter slit becomes minimal or is completely closed.

When the pressure of the cutter head 24 against the ground at the face, is increased above the passive earth pressure, this state is sensed via the load detector 38 and hence by the electric control device 96, and any of the servo-valves is controlled, so as to adjust any of rotation of the cutter head, a thrust for the shield body and the openings of cutter slits in a reverse fashion to that described above.

By controlling one of the rotation of the cutter head, a thrust for the shield body and the openings of cutter slits in a desired fashion, the amount of earth excavated can be increased or decreased, and the cutter head is pressed against the ground at the face usually under a pressure larger than the active earth pressure but smaller than the passive earth pressure, thus performing excavation of a tunnel while preventing falls of the face.

Fig. 4 shows a tunnelling machine according to a second embodiment of the present invention.

Components equivalent to those in the first embodiment are denoted by the same reference numerals for identification. The drive shaft 26 extends through a cylinder 112 attached to the rear wall of the gear box 28. The drive shaft 26 has a flange portion 114 serving as a piston in the portion located in the cylinder. The flange portion, namely the piston 114, of the drive shaft defines a cylinder chamber 116 in the rear portion of the cylinder, which cylinder chamber is communicated by a pressurized liquid pipe 1 8 with a hydraulic servo-device 120. The cutter head 24 is pressed against the face 100 by supply of a pressurized liquid into the cylinder chamber 116 in the cylinder 112.

The rear end of the drive shaft 26 extends through the cylinder chamber 112 rearward of the shield body. The piston-cylinder device 42 similar to that in the first embodiment shown in Fig. 1 is attached to the rear end portion of the drive shaft 26, with the piston rod 44 extending through the central longitudinal passage in the drive shaft 26 to terminate at the cutter head 24. The cutter head 24 and the piston rod 44 associated therewtih are the same in construction as shown in Fig. 2.

Another piston cylinder device 122 is attached to the shield body 12 at the rear of the pistoncylinder device 42, with one end of the piston rod 124 thereof attached to the cylinder portion of the piston-cylinder device 42 for use in adjusting the opening of respective cutter slit. The pistoncylinder device 122 has a function of detecting a degree of displacement, namely a distance of sliding movement, of the cutter head 24 relative to the shield body 12, because the cutter head 24 is so arranged as to be displaced in the axial direction independently of the direction of thrust to the shield body. The piston-cylinder device 122 is therefore a means for detecting a distance of sliding movement of the cutter head.The cylinder chamber of the detector 122 of the distance of sliding movement communicates via a pressurized liquid pipe 126 with a hydraulic servo-device 1 20 and likewise the piston-cylinder device 42 to the detector 122.

The hydraulically driven motor 32, the pistoncylinder device 42 and the shield-body thrusting jacks 66 of the tunnelling machine are connected via ducts 134, 136 and 138 and by means of valves 128,130 and 132 to variable pumps 140, 142 and 144, respectively. These variable pumps are connected to the hydraulic servo-device 120, so that an amount of hydraulic pressure supplied is controlled by hydraulic signals from the hydraulic servo-device. Since, in the hydraulic shield tunnelling machine 110, the cutter head 24 is separate from the shield body 12, a counterearth pressure may be produced at the cutter head 24, independent of advance of the shield body.

Therefore, a predetermined load by which the cutter head 24 is permitted to press against the face 100 under a pressure larger than the active earth pressure but smaller than the passive earth pressure, is usually applied to the cylinder chamber 1 6 in the piston-cylinder device 112. In order to apply such a load to the cylinder chamber 11 6, one or both of the advancing speed of the shield body 12 and the excavating speed of the cutter head 24 must be controlled so that both speeds can be synchronized with each other. The control of the speed or speeds is achieved by the method as referred to in conjunction with the tunnelling machine of Fig. 1.In more detail one of the rotation of the cutter head, the opening of respective cutter slit and the advancing speed of the shield body is controlled so that the cutter head 24 is usually maintained in a predetermined positional relationship to the shield body, that is, the cutter head may assume such a position relative to the shield body that it presses against the ground at the face under the pressure described above.

In a case where the ground at the face 100 contains ballast or gravel, the openings of cutter slits must be predetermined. Furthermore, a speed of excavation of the tunnelling machine must be predetermined because the advancing speed of the tunnelling machine tends to be irregular when the machine is started or stopped. In such cases, an amount of soil excavated is increased or decreased by controlling rotation of the cutter head alone.

The tunnelling machine 110 according to the second embodiment is of a type which is indirectly controlled on the basis of a distance of sliding movement of the cutter head relative to the shield body, unlike the tunnelling machine of Fig. 1 which directly controls a counter-earth pressure of the cutter head. The tunnelling machine of the second embodiment permits the cutter head to press against the face under a usually constant and stable pressure.

As an alternative, the distance of sliding movement of the cutter head relative to the shield body may be directly controlled by taking the difference between the speed of thrusting the shield body and the speed of excavation of the cutter head. The tunnelling machine shown in Fig. 5 is suited for embodying the method.

The hydraulic shield tunnelling machine 1 50 of Fig. 5 includes a bracket 1 52 attached to the rear end of the drive shaft in a suitable manner to rotate the drive shaft 26 extending through the piston-cylinder device 112 for use in pressing the cutter head. The hydraulically driven motor 32 for giving a drive force to the drive shaft 26 includes a speed-change lever 1 54 for controlling a speed of the motor. The top end of the lever 154 and the bracket 1 52 are connected to each other by a rod 1 56 parallel to the drive shaft 26.

Assuming that an amount of soil excavated is increased and the cutter head 24 is advanced at a speed higher than the speed of thrust of the shield body to thereby be slidingly displaced a distance a relative to the shield body, then the drive shaft 26 is displaced to the left as viewed in Fig. 5, whereas the speed-change level 1 54 is pivotally moved by the rod 156, thereby decelerating rotation of the hydraulically driven motor 32. However, the shield body 12 is usually thrust at a constant speed, and so the cutter head 24 which has been displaced a distance a is returned to its original position (as well) as rotation of the hydraulic motor 32 is accelerated.

The shield tunnelling machine 1 60 according to a fourth embodiment shown in Fig. 6 is so arranged as to automatically control the openings of cutter slits according to a distance of sliding movement of the cutter head 24 relative to the shield body 12. A downwardly extending bracket 1 62 is attached to the rear end of the drive shaft 26 in a manner to allow rotation of the drive shaft, which drive shaft extends through the piston cylinder device 11 2 for use in pressing the cutter head. A link member 164 is attached at one end thereof to the shield body 12 and pivoted at the other end thereof to the other end of the rod 1 66 which is pivoted at the other end thereof to the bracket 1 62 in parallel to the drive shaft 26.The other end of the rod 44 for adjusting the openings of the cutter slits, which extends through the central longitudinal passage in the drive shaft 26, is pivotally secured to the link member 1 64.

When a pressure of a predetermined level is applied to the piston cylinder device 122 during the tunnelling, in order to press the cutter head 24 against the face 100 under a pressure larger than the active earth pressure but smaller than the passive earth pressure, the amount of soil excavated at the face 100 becomes increased and the cutter head is advanced at a speed higher than the shield body and is thereby slidingly displaced relative to the shield body 12. The drive shaft 26 is then displaced to the left as viewed in Fig. 6, thereby pivotally moving the link member 164. As a result, the rod 44 is driven into the inner passage a distance proportional to an extent of displacement of the drive shaft 26, namely, a distance of sliding movement a thereof. However, the rod 44 projects from the rear end of the drive shaft 26, because of the relative movement of the drive shaft.As a result, the cutter bits 52 are forced into respective slits 48 in the face 46, thereby diminishing the opening of respective cutter slits. An amount of soil excavated by the cutter head is thus decreased, to thereby decelerate the speed of excavation, so that the cutter head will be returned to a predetermined position relative to the shield body.

According to the hydraulic shield tunnelling machine of the present invention, excavation of a tunnel is proceeded, with while preventing falls of the face, by pressing the cutter head against the ground at the face under a pressure larger than the active earth pressure but smaller than the passive earth pressure, and by applying a liquid under a pressure substantially equal to the pressure of underground water at the face into the liquid pressure chamber, unlike in the conventional method in which a speed of excavation is determined by measuring a density or a specific gravity of soil containing in the sludge flowing through the sludge pipe. The pressure against the face of the cutter head, is automatically controlled by adjusting any of the rotation of the cutter head, a speed of thrusting the shield body and the openings of respective cutter slits by the tunnelling machine of the present invention. While the pressure of the cutter head is usually exerted on the face, the positional reiationship of the cutter head relative to the shield body is controlled by adjusting rotation of the cutter head or the openings of respective cutter slits. According to this method, control of the pressure of the cutter head for preventing falls of the face is facilitated.

In this method, a pressurized water being introduced into the liquid pressure chamber may be fresh water.

Claims (9)

1. A hydraulic shield tunnelling method comprising the steps of, causing a liquid to act on the ground at a face under a pressure substantially equal to the pressure of underground water at the face during the tunnelling, and pressing a cutter head against the ground at the face under a pressure larger than an active earth pressure but smaller than a passive earth pressure by controlling at least one of rotation of said cutter head, a speed of thrusting a shield body and the openings of cutter slits, whereby falls of the face during the tunnelling is avoided.

2. A hydraulic shield tunnelling method as defined in Claim 1 , wherein said liquid is fresh water.

3. A hydraulic shield tunnelling method as defined in Claim 1, wherein said liquid is sludge.

4. A hydraulic shield tunnelling machine comprising, a shield body, a partition wall located internally of said shield body; a cutter head rotatably supported by said partition wall and having a plurality of slits, a device for supplying into a region at the front of said partition wall a liquid under a pressure substantially equal to the pressure of underground water at the face; a device for thrusting the shield body; a cutter-head driving device, a device for adjusting the openings of cutter slits, a device for detecting whether an earth pressure at the face is higher or lower than a predetermined value, and, a device for controlling operation of at least one of said shield-body thrusting device, said cutter-head driving device and said cutter-slit-opening adjusting device, according to the level of earth pressure at the face thus detected.

5. A hydraulic shield tunnelling machine comprising, a shield body, a partition wall located internally of said shield body, a cutter head rotatably supported by said partition wall in a manner to effect a linear movement and having a plurality of slits, a device for supplying into a portion at the front of said partition wall a liquid under a pressure substantially equal to the pressure of underground water at the face, a device for pressing said cutter head against the ground at the face under a pressure larger than the active earth pressure but smaller than the passive earth pressure, a device for thrusting the shield body, a cutter head driving device, a device for adjusting the openings cutter slits, a device for detecting a distance of sliding movement of said cutter head, and, a device for controlling operation of at least one of said shield-body thrusting device, said cutter-head driving device and said device for adjusting the openings of cutter slits.

6. A hydraulic shield tunnelling machine as defined in Claim 4 or 5, wherein respective slit in said cutter head is variable in the opening.

7. A hydraulic shield tunnelling machine as defined in Claim 4 or 5, wherein said shield-body thrusting device is variable in speed.

8. A hydraulic shield tunnelling machine as defined in Claim 4 or 5, wherein said cutter-head driving device is variable in speed.

9. A hydraulic shield tunnelling machine substantially as hereinbefore described with reference to Figures 1 to 6 of the accompanying drawings.