JP5996389B2 - Perfect circle holding device - Google Patents

Description

  The present invention relates to a perfect circle holding device that presses the inner surface of a segment covered in a ring shape on the inner surface of a tunnel excavated by a shield machine, and holds the shape.

A perfect circle holding device that holds the inner surface of a segment lined in a ring shape on the inner surface of a tunnel excavated by a shield machine, has at least a pair of left and right telescopic columns, and upper ends of these columns. And an upper arch suspended between the sections.
When the tunnel is dug in a straight line, the vertical center line (or outer diameter center) of the upper arch and the vertical center line (or axis center) of the tunnel coincide with each other. However, in the curved section where the tunnel is dug in a curved shape, the vertical center line of the tunnel deviates from the vertical center line of the upper arch. For example, when turning to the left, the vertical center line of the tunnel shifts to the left with respect to the vertical center line of the upper arch, and vice versa when turning to the right. Various perfect circle holding devices capable of coping with the deviation of the tunnel vertical center line with respect to the vertical center line of the upper arch have been proposed.

In the segment perfect circle holding device described in Patent Document 1, a pair of left and right support carriages 4R and 4L are disposed on a pair of left and right rails 2a on a support member (erection frame 2) so as to be movable in the front-rear direction. The left and right support carts 4R and 4L are provided with extendable columns 7R and 7L that are vertically extended by extendable jacks 9R and 9L. Divided holding frames 24R and 24L obtained by dividing the arc-shaped frame into the right and left at the center are arranged above the telescopic columns 7R and 7L.
The right end portion of the divided holding frame 24R is pin-coupled to the right end portion of the cradle 21R at the upper end of the telescopic column 7R, and the left end portion of the pedestal 21R and the divided holding frame 24R are connected by a tilting jack 25R, and the divided holding frame 24R is connected. It can be tilted around the pin connection. Similarly, the left end of the divided holding frame 24L is pin-coupled to the left end of the cradle 21L at the upper end of the telescopic column 7L, and the right end of the cradle 21L and the divided holding frame 24L are connected by a tilting jack 25L to divide and hold. The frame 24L is configured to be tiltable about pin coupling.

  In the shape holding device described in Patent Document 2, an arc-shaped spreader is attached to the upper ends of a pair of left and right telescopic members (an outer cylinder, an inner cylinder, and a hydraulic jack) that are movable along a pair of left and right rails on an overhanging table. A pair of left and right slide jacks that slide and move the left and right end portions of the spreader in the left and right directions while linking and supporting the left and right ends of the spreader with respect to the corresponding elastic members. Provided. When excavating the curved section of the tunnel, the horizontal position of the spreader is adjusted by the left and right slide jacks so that the vertical center line of the tunnel machine matches the vertical center line of the spreader. . An example in which a compression spring is employed instead of the slide jack is also disclosed.

Japanese Unexamined Patent Publication No. 2000-192793 JP 2001-115792 A

In the perfect circle holding device of the segment of patent document 1, since a cradle and a tilting jack are equipped on the upper end side of each telescopic column, a large space is required for their arrangement, and the inside of a narrow tunnel digging machine is required. It is disadvantageous in terms of equipment arrangement, and the production cost is also expensive.
In addition, the centers of the outer diameters of the left and right divided holding frames do not always coincide with each other, and there is a problem that the shape cannot be held in a perfect circle. In addition, since the left and right divided holding frames are not connected, there is a problem that the structure of the support carriage becomes complicated and large in size and the manufacturing cost becomes expensive in order to ensure the self-supporting property of the telescopic column and the divided holding frame. .

  In the shape holding device of Patent Document 2, since a mounting bracket and a slide jack having a large left and right width are provided on the upper end of the expansion and contraction member, a large space is required for the arrangement, and the equipment is arranged in a narrow tunnel machine. This is disadvantageous. Further, the manufacturing cost of a slide jack, a guide mechanism and the like for guiding and supporting the end of the spreader so as to be movable in the left-right direction is also increased.

If the strokes of the left and right slide jacks are not precisely controlled so that the vertical center line of the segment coincides with the vertical center line of the spreader, an eccentric load acts on one of the inner cylinders and the shape holding device is deformed. There is a risk of it. In addition, regardless of whether straight or curved, the vertical position of the spreader must be adjusted via the left and right slide jacks each time the vertical center line of the segment deviates from the vertical center line of the spreader. To do.
An object of the present invention is to provide a perfect circle holding device capable of maintaining the shape of a segment with a uniform pressing force in a bending section, and to provide a perfect circle holding device that is advantageous in terms of space and in terms of manufacturing cost. It is to be.

The perfect circle holding device according to claim 1 is a perfect circle holding device that holds the shape by pressing the inner surface of the segment covered in a ring shape on the inner surface of the tunnel excavated by the shield machine, and is parallel to the axis of the shield machine A pair of left and right movable bases that can move on a support member extending in a pair, a pair of left and right telescopic columns that are vertically extendable on the pair of movable bases, and upper ends of the pair of telescopic columns A pair of left and right pins that are coupled to the upper arch and the upper arch of the pair of telescopic columns so that the upper arch can pivot about an axis parallel to the axis of the shield machine. And a pair of left and right urging means for urging the pair of left and right telescopic columns so as to be in a vertical posture. Each of the urging means has an upper end fixed to the upper arch and extends downward. The left and right sides of the arm member and the lower end of the arm member And a pair of spring means disposed horizontally opposite to each other.

According to a second aspect of the present invention, there is provided a perfect circle holding device according to the first aspect , wherein each of the telescopic columns is externally fitted to the inner cylinder member fixed to the movable base, and to the inner cylinder member so as to be extendable and contractible from above. An outer cylinder member connected to the pin coupling mechanism, and an inner cylinder member and a hydraulic cylinder disposed inside the outer cylinder member and capable of driving the outer cylinder member up and down are provided.

According to a third aspect of the present invention, in the invention according to the first or second aspect , each of the movable bases has a pair of front and rear idlers that can roll on a rail fixed to the support member. It is characterized by.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, each pin coupling mechanism includes a spherical bearing.

According to the first aspect of the present invention, a pair of left and right telescopic columns, an upper arch constructed over the upper ends of these telescopic columns, and an upper end of the pair of left and right telescopic columns are shielded in the upper arch. The upper arch is separated from the segment and the vertical center line of the perfect circle holding device and the vertical length of the upper arch are provided. Even if the vertical center line of the upper arch is shifted to the left or right from the vertical center line of the segment from the neutral position where it matches the center line, the left and right telescopic columns are extended. As a result, the left end or the right end of the upper arch first comes into contact with the inner surface of the segment, and then the right arch or the left end of the upper arch comes into contact with the inner surface of the segment while the upper arch tilts slightly.
In this way, the outer surface of the upper arch can be brought into close contact with the inner surface of the segment with an equal pressing force (without applying an uneven load) and can be held in a perfect circle shape.

  In addition, since a pair of left and right urging means for urging the pair of left and right telescopic columns to be in a vertical posture is provided, when the perfect circle holding device is released, the pair of urging means By the urging force, the pair of telescopic columns are urged so as to be in a vertical posture, and automatically return to the neutral position where the longitudinal center line of the perfect circle holding device coincides with the longitudinal center line of the upper arch. Therefore, since the upper arch can be pressed against the inner surface of the segment from the neutral position, the reliability and durability can be maintained without damaging the segment or deforming the perfect circle holding device due to uneven load. Excellent. In addition, the pin coupling mechanism and the urging means have a small number of parts and can be configured in a small structure, so that a large space is not required and the manufacturing cost is advantageous.

Each urging means may be configured with the arm member, a capable manufactured a pair of small simple structure comprising a spring means inexpensive.

According to the invention of claim 2 , each of the telescopic columns includes an inner cylinder member, an outer cylinder member fitted on the inner cylinder member, and an inner cylinder member and an outer cylinder member arranged inside the outer cylinder member. Since it has a structure including a hydraulic cylinder that can be driven up and down, it has a simple structure excellent in stretchability.

According to the invention of claim 3 , each movable table has a pair of front and rear idlers that can roll on the rail member fixed to the support member. The shield machine can be moved while digging while holding the perfect circle holding device relatively stationary with respect to the tunnel.

According to the invention of claim 4 , since each of the pin coupling mechanisms includes a spherical bearing, the outer surface of the upper arch can be brought into close contact with the inner surface of the segment even when the tunnel bends in the vertical direction. .

It is a side view of the rear part of a shield machine and a perfect circle holding device concerning an example of the present invention. It is a rear view of a segment and a perfect circle holding device. It is a top view of a support beam rear part, a movable stand, a telescopic column, a movement drive mechanism, and the like. It is a side view of a movable stand, a telescopic column, a pin coupling mechanism, and an urging mechanism. It is a partial longitudinal rear view of a movable stand, an extendable column, and a pin coupling mechanism. It is a principal part rear view of an upper arch, an expansion-contraction column, a pin coupling mechanism, and an urging mechanism. It is a principal part rear view of an upper arch, an expansion-contraction column, a pin coupling mechanism, and an urging mechanism. It is a rear view of the segment and shape perfect circle holding device before shape maintenance start. It is a rear view of the segment in a shape maintenance state, and a perfect circle maintenance device. It is a rear view of the segment and shape perfect circle holding device before shape maintenance start. It is a rear view of the segment after a shape maintenance start, and a perfect circle holding device. It is a rear view of the segment in a shape maintenance state, and a perfect circle maintenance device.

  Hereinafter, modes for carrying out the present invention will be described based on examples.

  As shown in FIGS. 1 and 2, in the shield machine 1 according to the present embodiment, an erector (not shown) for covering a segment on the inner surface of the tunnel, and a perfect circle holding device 10 in the body member 2 thereafter. And are provided. In the following description, the forward direction of tunnel excavation is the front (left side in FIG. 1), and the left-right direction when facing forward is the left-right direction.

 The perfect circle holding device 10 is mounted on a pair of left and right support beams 3 parallel to the axis A of the shield machine 1. The front end portions of the pair of support beams 3 are fixed to a main body structural member 4 (post) fixed to the rear trunk member 2. When digging the tunnel, the shield digging machine 1 is moved forward by taking a reaction force on the segment S at the front end of the covered segments S by the plurality of shield jacks 5, and the digging is stopped every time one digging is performed for one ring. Then, after the segment S for one ring is covered on the inner surface of the tunnel, the next one ring is dug. One ring excavation and one ring segment lining are one cycle of tunnel excavation. This perfect circle holding device 10 presses the upper end side portion of the latest one ring segment covered in a ring shape from below, and is injected for about one cycle of tunneling (injected on the outer surface side of the segment S). (Including the curing period of the mortar).

  The perfect circle holding device 10 is provided on a pair of left and right support bases 3 (which correspond to support members) that can move in the front-rear direction, and a pair of left and right bases 20, respectively. A pair of left and right telescopic columns 30 provided, an upper arch 40 extending over the upper ends of the pair of telescopic columns 30, and the upper ends of the pair of telescopic columns 30 are pin-coupled to the upper arch 40. A pair of pin coupling mechanisms 50, a pair of left and right biasing mechanisms 60 (biasing means) for biasing the pair of telescopic columns 30 so as to be in a vertical posture, and a pair of left and right moving bases 20 are moved forward and backward. A pair of left and right movement drive mechanisms 70 for moving in the direction are provided.

First, the moving table 20 will be described.
As shown in FIGS. 1 to 3, the left and right support beams 3 and the left and right moving bases 20 are symmetrically configured, so the right support beam 3 and the right moving base 20 will be described.
A rail 6 is disposed on the support beam rear portion 3a, which is a rear portion of the support beam 3, so as to extend a predetermined length (a length corresponding to about two rings) in the front-rear direction. The idler wheel 21 rolls on the rail 6 and the movable table 20 is movable along the rail 6 in the front-rear direction.

Next, the telescopic column 30 will be described.
As shown in FIGS. 1 to 5, the pair of left and right telescopic columns 30 are erected on the pair of left and right movable bases 20 and configured to be extendable in the vertical direction. Since the left and right telescopic columns 30 are symmetrical, the right telescopic column 30 will be described.

  The telescopic column 30 includes a cylindrical inner cylinder member 31 in a vertical posture whose lower end is fixed to the movable base 20, and a cylindrical outer cylinder that is externally fitted to the inner cylinder member 31 so as to be extendable and slidable. A cylinder member 32 and a hydraulic cylinder 33 that is disposed vertically inside the inner cylinder member 31 and the outer cylinder member 32 and can drive the outer cylinder member 32 up and down are provided.

The base plate 22 is fixed to the upper end of the movable table 20, and the connecting fitting 33 b fixed to the lower end of the cylinder main body 33 a of the hydraulic cylinder 33 is connected to the connecting fitting 34 fixed to the base plate 22 in the left-right direction pin 35. It is pin-coupled through.
The connecting fitting 36 at the tip of the output rod 33 c of the hydraulic cylinder 33 is pin-coupled to a connecting fitting 37 fixed to the back surface of the lid plate 32 a at the upper end of the outer cylinder member 32 via a pin 38 directed in the left-right direction. When the output rod 33c of the hydraulic cylinder 33 is retracted, the outer cylinder member 32 is lowered to the contracted state shown in FIGS. When the output rod 33c of the hydraulic cylinder 33 is extended from this state, the outer cylinder member 32 extends upward and extends by the stroke of the hydraulic cylinder 33.

  A hydraulic hose 39a that supplies and discharges hydraulic pressure to the forward oil chamber of the hydraulic cylinder 33 and a hydraulic hose 39b that supplies and discharges hydraulic pressure to the backward oil chamber of the hydraulic cylinder 33 are connected and pass through the hydraulic hoses 39a and 39b. Slits 32c and 32b are formed in the outer cylinder member 32.

Next, the upper arch 40 will be described.
As shown in FIGS. 1 to 5, the upper arch 40 has an arc shape having an outer diameter equal to the inner diameter of the laid segment S, and has a circumferential direction of about 1/5 to 1/4 of the circumference. It has a length and is installed over the upper ends of a pair of left and right telescopic columns 30.
The upper arch 40 is configured as a closed cross-section member having a rectangular cross section by two web plates 41, an inner diameter side flange 42 and an outer diameter side flange 43. In order to prevent the segment S from being damaged when the segment S is pressed, an elastic buffer plate 44 made of a synthetic resin (for example, polyurethane) is attached to the outer surface of the outer diameter side flange 43 of the upper arch 40. ing.

Next, the pin coupling mechanism 50 will be described.
As shown in FIG. 2 and FIG. 4 to FIG. 7, the left and right 1 are respectively connected to the upper arch 40 so that the upper ends of the pair of telescopic columns 30 can rotate about an axis parallel to the shield machine axis A. A pair of pin coupling mechanisms 50 are provided. Since the left and right pin coupling mechanisms 50 are symmetrically configured, the right pin coupling mechanism 50 will be described.

The pin coupling mechanism 50 includes a pair of front and rear pivot support brackets 51 fixed to the cover plate 32 a of the outer cylinder member 32 of the telescopic column 30 and a cylinder fixed to the right end of the two web plates 41 of the upper arch 40. And a pair of pivot brackets 51 and a pivot pin 54 in the front-rear direction which is inserted into the bearing member 53 and pin-couples them.
Since the left and right ends of the upper arch 40 are respectively connected to the upper ends of the pair of telescopic columns 30 by the pin coupling mechanism 50, the upper arch can be adjusted by appropriately adjusting the extension amount of the pair of telescopic columns 30. 40 can be set to a left-downward or right-downward inclined posture.

Next, the urging mechanism 60 (urging means) will be described.
As shown in FIGS. 2 and 4 to 7, a pair of right and left urging mechanisms 60 that urge the pair of telescopic columns 30 to be in a vertical posture are provided. Since the right and left urging mechanisms 60 are symmetrical, the right urging mechanism 60 will be described. The urging mechanism 60 includes an arm member 61 and a pair of spring means 66.

  The upper end of the arm member 61 is fixed to the vicinity of the right end of the upper arch 40, and the arm member 61 extends downward to the rear side of the upper portion of the telescopic column 30. The arm member 61 has a tapered arm plate 62 (the web plate 41 of the upper arch 40) whose upper end is fixed to a cylindrical member 64 that protrudes rearward and is fixed to the vicinity of the right end of the upper arch 40 and that becomes narrower downward. Arm rib parallel to the rear surface), reinforcing ribs 63 orthogonal to the rear surface are fixed.

  The pair of spring means 66 are horizontally disposed opposite to the left and right sides of the lower end of the arm member 61 and are attached to a base member 65 fixed to the outer cylinder member 32 of the telescopic column 30. Each spring means 66 includes a guide member 67 fixed to the base member 65, a push rod 68 inserted through the guide member 67 so as to be slidable in the left-right direction, and the push rod 68 mounted on the push rod 68. A compression spring 69 that elastically biases the arm member 61. Note that two nuts 68 a for receiving the end of the compression spring 69 are fixed to the end of the push rod 68.

As shown in FIG. 6, when the upper arch 40 is in a neutral posture (horizontal posture), a small pressing force acts symmetrically on the arm member 61 from the spring means 66 on both sides, and the telescopic column 30 maintains the vertical posture. To do. As shown in FIG. 7, when the upper arch 40 is inclined upward to the left, the urging force is not applied from the outer spring means 66 and the urging force of the compression spring 69 of the inner spring means 66 is increased. Therefore, the upper arch 40 is urged in a direction to return to the horizontal posture, and the telescopic column 30 is urged in a direction to return to the vertical posture.
As described above, since the compression spring 69 is employed, a large urging force can be generated even when the displacement of the lower end portion of the arm member 61 is small.

Next, the movement drive mechanism 70 that moves the moving table 20 in the front-rear direction will be described.
Since the left and right movement drive mechanisms 70 are similar, the right movement drive mechanism 70 will be described. As shown in FIGS. 1 and 3, the movement drive mechanism 70 includes a connection base 71 fixed to the upper surface of the rear end of the support beam rear portion 3 a, and a slider link that connects the connection base 71 and the movement base 20. 72 and a hydraulic cylinder 75 for raising and lowering the slider link 72.

  The slider link 72 is obtained by pin-coupling two link members 73 and 74 arranged in the front-rear direction, and the front end portion of the link member 73 is pin-coupled to the rear end portion of the movable table 20 with a horizontal pin directed in the left-right direction. The rear end portion of the link member 73 and the front end portion of the link member 74 are pin-coupled with a horizontal pin that faces in the left-right direction, and the rear end portion of the link member 74 is horizontally connected to the lower portion of the connection base 71 in the left-right direction. Pin-connected with pins. The hydraulic cylinder 75 is disposed in a state along the vicinity of the rear side of the link member 74, and the lower end portion of the cylinder body of the hydraulic cylinder 75 is pin-coupled to the upper portion of the coupling base 71 with a horizontal pin in the left-right direction. The front end portion of 75 output rods 75a is pin-coupled to the vicinity of the upper end of the link member 74 with a horizontal pin directed in the left-right direction. The slider link 72 is configured to operate in a vertical plane without tilting in the left-right direction.

  In a state where the output rod 75a of the hydraulic cylinder 75 is retracted as much as possible, the ring member 74 is raised, the slider link 72 is raised in a bent state, and the moving base 20 is in the retreat limit position (shown by a chain line in FIG. 1). . In accordance with the extension of the output rod 75a, the slider link 72 falls to the lying side and the moving base 20 moves forward. When the output rod 75a is extended to the maximum, the moving base 20 moves to the advance limit position (see FIG. 1). (Shown with a solid line). Since the movement drive mechanism 70 moves the perfect circle holding device 10 back and forth in a state where the shape retention by the upper arch 40 is released, the perfect circle holding device 10 is moved by the driving force of the small hydraulic cylinder 75. Can be made. The left and right hydraulic cylinders 75 are controlled to operate synchronously.

Next, the operation and effect of the perfect circle holding device 10 will be described.
FIGS. 8 and 9 show the relationship between the perfect circle holding target segment S and the true circle holding device 10 when digging straight. In this case, the vertical center line of the shield machine 1 (the vertical center line of the perfect circle holding device 10) matches the vertical center line of the segment S, and the center (axial center) of the shield machine 1 and the upper arch 40 The center of the outer diameter of each segment coincides with the center of the inner diameter of the segment S for one ring. Therefore, when the left and right telescopic columns 30 are evenly extended when holding the perfect circle, the upper arch 40 abuts the inner surface of the segment S over the entire length with a uniform pressing force. The shape can be held by holding the segment S in a perfect circle shape while keeping the vertical posture.

  10 to 12 show a relationship between the perfect circle holding target segment S and the true circle holding device 10 in a curved section that is curved in a curved shape to the left, for example. However, the amount of deviation between the vertical center line B of the perfect circle holding device 10 and the vertical center line C of the segment S, the amount of deviation between the center A of the outer diameter of the upper arch 40 and the center D of the inner diameter of the segment S, etc. are exaggerated. It is shown. In the example shown here, since it digs in a curved shape to the left, the vertical center line D of the segment S tends to shift to the left with respect to the vertical center line B of the perfect circle holding device 10.

When the left and right telescopic columns 30 are evenly extended from the state of FIG. 10, the right end portion of the upper arch 40 comes into contact with the inner surface of the segment S as shown in FIG. In this state, the right telescopic column 30 does not extend any more, and when only the left telescopic column 30 is expanded, the upper arch 40 is centered on the right pin coupling mechanism 50 as shown in FIG. And the upper arch 40 contacts the inner surface of the segment S with a uniform pressing force over the entire length. In this state, the segment S can be held in a perfect circle shape.
At this time, since the upper arch 40 does not hit the segment S and the eccentric load does not act, the segment S is not damaged, and an unreasonable load acts on the perfect circle holding device 10. In addition, operational reliability and durability can be improved.

  At this time, the idler wheels 21 of the left and right moving bases 20 can be inclined with respect to the rail 6, respectively, so that the upper arch 40 is raised to the left while the left and right telescopic columns 30 or the left telescopic column 30 are slightly tilted to the right. It becomes the inclination posture of. In this state, the compression of the spring means 66 outside the left urging mechanism 60 and the spring means 66 inside the right urging mechanism 60 further proceeds, and the urging force is strengthened (see FIG. 7).

  When the right and left urging mechanisms 60 are urged so that the upper arch 40 returns to the horizontal posture and the left and right telescopic columns 30 return to the vertical posture, when the perfect circle is released. The left and right telescopic columns 30 are contracted, and after the upper arch 40 is separated from the segment S, when the left and right telescopic columns 30 are equal in height, the upper arch 40 automatically returns to the horizontal posture. The left and right telescopic columns 30 automatically return to the vertical posture, and automatically return to the neutral position where the vertical center line B of the perfect circle holding device 10 and the vertical center line B of the upper arch 40 coincide.

  Therefore, when the next perfect circle is held, the upper arch 40 can be pressed against the inner surface of the segment S from the neutral position, so that the segment S is damaged or the perfect circle holding device 10 is damaged. There is nothing. In addition, the left and right movement drive mechanism 70 adjusts the position of the upper arch 40 in the left-right direction only by performing an operation of moving the perfect circle holding device 10 forward by one ring and an operation of extending the left and right telescopic columns 30. Since this operation is not necessary, it is possible to efficiently maintain a perfect circle.

  The upper arch 40 of the integral member and the left and right telescopic columns 30 form a gate shape, and the left and right urging means 60 cause the upper arch 40 to be in a horizontal posture, and the left and right telescopic columns 30 are in a vertical posture. In addition, since the left and right moving platforms 20 each have a pair of front and rear idlers 21, the perfect circle holding device 10 has no risk of falling in both the front-rear direction and the left-right direction. Excellent independence. Therefore, the structures of the left and right movable bases 20 and the rails 5 can be simplified and downsized.

In addition, the pin coupling mechanism 50 and the urging mechanism 60 have a small number of parts and can be configured in a small structure, so that a large space is not required and the manufacturing cost is advantageous.
The urging mechanism 60 can be configured to be small and inexpensively manufactured with a simple structure including an arm member 61 and a pair of spring means 66.

  The telescopic column 30 includes an inner cylinder member 31, an outer cylinder member 32 slidably fitted to the inner cylinder member 31, and the inner cylinder member 31 and the outer cylinder member 32. Since it has a structure including the hydraulic cylinder 33 that can be driven up and down, it has a simple structure excellent in stretchability and guideability when stretched.

  Since the movable table 20 has a pair of front and rear idlers 21 that can roll on the rail 6 fixed to the support beam rear portion 3a, the perfect circle holding device 10 is maintained in a state where the shape is held on the inner surface of the segment S. Can be moved forward while the shield machine 1 is kept stationary relative to the tunnel.

Next, a modification example in which the perfect circle holding device 10 is partially changed will be described.
(1) A spherical bearing may be adopted for the pin coupling mechanism 50 so that the upper arch 40 can be tilted in the front-rear direction. In that case, the outer surface of the upper arch 40 can be brought into close contact with the inner surface of the segment S when the tunnel is dug upward or downward.

(2) Although the compression spring 69 is employed as the spring means 66 in the urging mechanism 60, a spring that does not impart a preload that is a natural length when the upper arch 40 is in the neutral position may be employed.
(3) Instead of the compression spring 69, a gas spring or a hydraulic cylinder connected to an accumulator may be adopted as the spring means 66 in the urging mechanism 60.

  The perfect circle holding device according to the present invention is a device for holding the shape of a segment during tunnel excavation, and can be applied to various shield machines.

1 Shield machine 3 Support beam (support member)
DESCRIPTION OF SYMBOLS 10 Perfect circle holding | maintenance apparatus 20 Moving stand 21 Free wheel 30 Telescopic column 31 Inner cylinder member 32 Outer cylinder member 33 Hydraulic cylinder 40 Upper arch 50 Pin coupling mechanism 60 Energizing mechanism 61 Arm member 66 Spring means

Claims (4)

In the perfect circle holding device that holds the shape by pressing the inner surface of the segment covered in a ring shape on the inner surface of the tunnel excavated by the shield machine,
A pair of left and right moving platforms movable on a support member extending in a direction parallel to the shield machine axis;
A pair of left and right extendable columns that are vertically installed on the pair of movable bases and extend vertically.
An upper arch constructed over the upper end of the pair of telescopic columns;
A pair of left and right pin coupling mechanisms that respectively couple the upper ends of the pair of telescopic columns to the upper arch so as to be pivotable around an axis parallel to the shield machine axis;
A pair of left and right biasing means for biasing the pair of telescopic columns so as to be in a vertical posture ;
Each of the urging means includes an arm member having an upper end fixed to the upper arch and extending downward, and a pair of spring means disposed horizontally opposite to both the left and right sides of the lower end of the arm member. A perfect circle holding device. Each of the telescopic columns includes an inner cylinder member fixed to the movable table, an outer cylinder member that is externally fitted to the inner cylinder member so as to be extendable and connected to the pin coupling mechanism, an inner cylinder member, and an outer cylinder member. The perfect circle holding device according to claim 1 , further comprising a hydraulic cylinder disposed inside the cylindrical member and capable of driving the outer cylindrical member up and down . 3. The perfect circle holding device according to claim 1, wherein each of the movable platforms has a pair of front and rear idlers that can roll on a rail fixed to the support member . Each said pin coupling mechanism is provided with the spherical bearing, The perfect circle holding device of any one of Claims 1-3 characterized by the above-mentioned.