JPH0571296A - Shield excavator - Google Patents

Abstract

PURPOSE:To keep a lining material always under higher pressure than the earth pressure and water pressure of a bedrock even when a shield excavator is intermittently driven forward or there are voids in the bedrock. CONSTITUTION:A shield excavator is constituted of skin plates 11 as an outer shell, a cutter device 12 excavating a bedrock and driving jacks 13. Each tail section of the skin plates 11 is constituted of an outer cylinder 20 and an inner cylinder 21 having a smaller diameter than that of the outer cylinder 20. A concrete piston room 23 is provided between the outer cylinder 20 and the inner cylinder 21, a pushing-out piston 24 is provided to the inside of the concrete piston room 23, and the pushing-out piston 24 is so stored that it is capable of sliding back and forth by means of a pressure holding jack 25 through a spring device 70. Accordingly, even when the shield excavator is intermittently driven forward or when there are voids in the bedrock, the pressure can be sufficiently held to surely prevent pressure lowering and, at the same time, a lining material having high strength and high quality can be placed without water-leaking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield machine, and particularly to footwear materials such as cast-in-place concrete.
The present invention relates to a shield machine suitable for application to an execution method of wearing shield tunnels.

[0002]

2. Description of the Related Art In the method of wearing a shield tunnel, the method of using cast-in-place concrete is usually
Using a shield machine with a cylindrical outer shape, while excavating the ground with a cutter device provided in front of this shield machine, the peripheral wall of the tunnel that has been machined is covered with a form at a predetermined interval, and this form is used. The step of arranging a reinforcing bar between the above and the peripheral wall, placing concrete, pressing the concrete by the operation of the pressing jack, and advancing the shield excavator as a whole is repeated.

By the way, in such a construction method, the end frame of the pressing jack is provided with a gable frame ring so as to close the space between the form frame and the tunnel peripheral wall. The gable frame ring is refilled during the rebar assembly and moves along with the rod of the pressing jack. At this time, the pressure of the concrete cannot be maintained, so the earth and sand,
Groundwater mixes in and high quality concrete cannot be placed, causing concrete damage and water leakage. In order to depend on the strength of the concrete, it is necessary to cure the concrete until the strength of the concrete is manifested, and there is a problem that the construction time becomes long.

Therefore, as a means for solving such a problem, in the prior art, an annular pressure ring for retaining the compression of concrete by taking a reaction force in cast-in-place concrete is provided between the formwork and the tunnel peripheral wall. Japanese Patent Application Laid-Open No. 1-190900, "Casting machine, excavator" discloses a means for arranging while holding it by a tie rod and embedding it in footwear material.

[0005]

However, even with such means of the prior art, there still remain the following problems to be solved. Firstly, in the means of the prior art, since there is no pressure maintaining device for keeping the concrete pressure higher than the natural pressure, the pressure gradually decreases even if the pressure can be retained at the beginning. That is the point. Second
In addition, the pressure retaining ring enables smooth digging and reinforcement.
Even if the pressure can be maintained when the formwork is assembled, if the shield machine progresses intermittently or there are cavities in the ground,
Due to the sudden increase in the volume required for concrete filling, a sharp drop in pressure occurred, making it difficult to construct high-quality concrete footwear.

The present invention effectively solves the above-mentioned problems, and its object is to keep the pressure of the footwear material constant even when the shield machine progresses intermittently or when there are cavities in the ground. It is an object of the present invention to provide a shield machine capable of assembling reinforcing bars and placing concrete while maintaining a higher earth pressure / water pressure than that of natural ground, and performing high-quality work.

[0007]

A shield machine according to claim 1 is rotated by a cylindrical skin plate forming an outer shell and a driving means provided at a front end portion of the skin plate, and the ground excavation is performed. In a shield machine equipped with a cutter device for excavating and a propulsion jack having a base end connected to a partition plate formed inside the skin plate,
The tail portion of the skin plate is double formed by an outer cylinder and an inner cylinder, and a plurality of partition walls extending in the radial direction of the skin plate are formed between the inner cylinder and the outer cylinder of the tail portion to accommodate the pushing piston. A plurality of concrete piston chambers are provided, an extrusion piston is inserted into the concrete piston chambers, a plurality of pressure holding jacks are provided on the partition plate, and the pressure holding jacks and the pushing pistons are connected via an elastic device. A shield machine that is characterized by being.

A shield machine according to a second aspect of the present invention is the shield machine according to the first aspect, characterized in that the spring is provided in the elastic device.

A shield machine according to a third aspect of the present invention is the shield machine according to the first aspect, wherein the elastic device is provided with an air damper.

[0010]

According to the shield machine of claim 1, since the pressure holding jack and the pushing piston are connected via the elastic device, the shield machine progresses intermittently,
When there is a hollow in the ground, the pushing piston can be pushed out quickly to prevent a sudden pressure drop, and then the pressure holding jack can be extended to hold a predetermined pressure. Since the concrete piston chamber is provided by forming the partition wall, a plurality of concrete piston chambers can be manufactured in advance in a factory or the like. For this reason, the concrete piston chamber can be manufactured with high precision, a seal that can withstand high pressure can be manufactured, and the piston can be safely removed from the concrete piston chamber after the concrete has hardened. Can be easy.

Further, since the pressures of the pushing pistons in the plurality of concrete piston chambers formed in the tail portion are individually controlled by the pressure holding jacks, the pressure of the footwear material in each chamber can be individually controlled. It is possible to easily deal with the difference in the ground pressure depending on the height, and it is possible to always keep the pressure of the footwear material higher than the earth pressure and water pressure of the ground. Further, by such an action, the tail void is surely filled with the footwear material, and the risk of sinking is eliminated. Further, when the supply pressure of the footwear material becomes larger than the set holding pressure of the pressure holding jack, the supply pressure of the footwear material is configured to move the pushing piston forward of the shield machine. The extruding piston moves to the rear of the shield machine when pushing the footwear material and to the front when putting the footwear material into the piston chamber, so that the pressure inside the concrete piston chamber can be kept almost constant even when the footwear material is supplied. It will be possible.

According to the shield machine of claim 2,
In addition to having the function of claim 1, the pressure holding jack and the pushing piston are connected via an elastic device, and the elastic device is provided with a spring, so that the shield machine progresses intermittently, If there are cavities in the ground,
A spring that takes a short time to expand and contract (good followability) stretches due to the decrease in concrete pressure, quickly pushes out the extrusion piston, prevents a sudden decrease in pressure, and then retains a predetermined pressure by extending the pressure holding jack can do.

According to the shield machine of claim 3,
In addition to the operation according to claim 1, the pressure holding jack and the pushing piston are connected to each other through the elastic device, and the elastic device is provided with the air damper. , When there is a cavity in the ground, the air damper stretches due to the decrease in concrete pressure, quickly pushes out the extrusion piston to prevent a sudden drop in pressure, and then stretches the pressure holding jack to maintain a predetermined pressure. be able to. Here, by the air damper, it is possible to suppress the fluctuation between the pressure of the air damper after pushing out the pushing piston and the set pressure of the pressure holding jack to be very small.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the vicinity of the face of a tunnel under construction according to the present invention. In the figure, reference numeral 10 is a shield machine, and the shield machine 10
Is excavating the tunnel T on the left side with respect to the plane of the drawing by a cutter device 12 provided at the front part thereof, while the peripheral wall of the tunnel T formed behind the shield excavator 10 is opened at a predetermined interval to form the frame 1 And the reinforcing bars U are arranged between the formwork 1 and the peripheral wall, and the footwear material is supplied to construct the footwear wall W on the inner surface of the tunnel. By providing the end frame 50 and the auxiliary end frame 51 on the shield machine 10 side of the form 1, it is possible to prevent the footwear material from leaking.

Next, the shield machine 10 according to the present invention will be described more specifically. This is a cylindrical skin plate 11 forming an outer shell, and this skin plate 11.
A cutter device 12 provided at the front end of the skin plate for excavating the ground by being rotated by a driving means (not shown); and a propulsion jack 13 having a base end connected to a partition plate 11a formed inside the skin plate 11. It has a basic structure equipped with.

The tail portion of the skin plate 11 has an outer cylinder 20 having the same diameter as that of the skin plate 11 and forming a part of the skin plate 11, and an inner cylinder 21 having a diameter smaller than that of the outer cylinder 20. The outer cylinder 20 and the inner cylinder 21 are connected by a plurality of partition walls 22 extending in the radial direction of the skin plate 11, as shown in FIG. A plurality of (four chambers in the illustrated example) concrete piston chambers 23 are provided between the outer cylinder 20 and the inner cylinder 21, and extrusion pistons 24 are slidably housed in the respective concrete piston chambers 23. There is. A double inner cylinder (not shown) is provided inside the outer cylinder 20.
May be provided, and a plurality of concrete piston chambers 23 may be provided in these double inner cylinders.

As shown in detail in FIGS. 2 to 3, the extruding piston 24 is formed in such a size that it fits tightly in the concrete piston chamber 23 in accordance with the internal shape of the concrete piston chamber 23, and the partition Board 11a
A plurality of pressure holding jacks 25 with their base ends attached to
(FIG. 1) is configured to slide back and forth. The pushing piston 24 and the pressure holding jack 2
5 and 5 are connected via an elastic device 70 having a short expansion and contraction operation time, such as a coil spring or a leaf spring (FIG. 4). The pressure holding jack 25 for operating the pushing piston 24 is provided with a relief valve,
The jack is contracted when the driving pressure of the lining material supply pump 31 becomes higher than the holding pressure of the jack.

A plurality of (two in the embodiment) seal members 26 are attached to the outer circumference of the extruding piston 24, and the inside of the skin plate 11 and the concrete piston chamber 23 are provided at the center of the extruding piston 24. Is formed with a lining material filling hole 24a that communicates with the lining material, and the filling hole 24a is formed on the inner surface of the extrusion piston 24.
A joint portion 27 is provided which communicates with a and is connected to the casting pipe 30 of the lining material (see FIG. 3). In the embodiment, the filling hole 24a is pushed out to the piston 2
However, the present invention is not limited to this embodiment.

The filling hole 24a has a filling hole 24a.
A blocking mechanism 28 for opening / closing a is attached (see FIG. 3), and the filling hole 24a can be opened / closed as necessary. The shutoff mechanism 28 is, specifically,
Filling hole 2 which is composed of shutter, valve, etc.
Other configurations may be used as long as they can open and close 4a.

Further, in FIG. 1, reference numeral 30 denotes a pipe for placing a lining material, and the pipe 30 is a branch valve 33 connected to a supply pipe 32 of a supply pump 31 for the lining material.
One end is connected to, and concrete or the like extruded by the supply pump 31 is divided by a branch valve 33,
Enter each concrete piston chamber 23. Further, the casting pipe 30 itself connecting the supply pump 31 and the concrete piston chamber 23 is constituted by a flexible pipe or a telescopic pipe so that it can cope with the movement of the pushing piston 24.

Further, in the drawing, reference numeral 50 is a main gable frame for closing the space between the inner cylinder 21 and the form 1, and the main gable frame 50 is
It has a basic configuration in which a plurality of plate bodies curved corresponding to the curvature of the inner surface of the inner cylinder 21 are combined in a ring shape in the longitudinal direction. In addition, an auxiliary gable frame 51 that closes the gap is set in the gap between the mold 1 and the main gable frame 50.

Next, the case of carrying out the shield tunnel lining method by applying the shield machine according to the present invention configured as described above will be described in order of steps with reference to FIGS. 3 to 8.

(I) Placing preparation step When performing concrete pouring to the outside, as shown in FIG. 3, the pushing pressure of the pressure holding jack 25 is made to correspond to the difference in natural pressure depending on the height. The size of the poured concrete is set so that it can always apply a pressure higher than the pressure of the ground, and the driving pipe 30 is connected to the joint portion 27 of the extruding piston 24 and the filling port of the extruding piston 24 is connected. It is set so that the lining material can be supplied into the concrete piston chamber 23 through 24a. Also, delay type concrete or the like is applied as the lining material, and the pressure is set to be transmitted to the rear. The concrete piston chamber 23 is
Needless to say, the seal member 26 is manufactured in advance in a factory with high precision and formed so as to withstand high pressure.

(Ii) Concrete Placing Process in Concrete Piston Chamber After preparation for concrete pouring is completed, concrete is sent from the supply pump 31 to the placing pipe 30, and the placing pipe 3
Concrete is poured into the concrete piston chamber 23 through the filling port 24a of the extrusion piston 24 through 0. More specifically, as shown in FIG. 1, the shield machine 10
By adjusting the pressing force of the pressure holding jack 25 of the extrusion piston 24 provided in the concrete piston chamber 23 of
The concrete pressure Po generated by the action of the pushing piston 24 is kept higher than the ground pressure Pj, and concrete is supplied from the casting pipe 30 toward the concrete piston chamber 23 at a pressure higher than the pressure of the pressure holding jack 25. Then, concrete is placed in the concrete piston chamber 23. At this time (when the concrete is placed in the concrete piston chamber 23), the pushing piston 24 receives a force in a direction against the pressing force of the pressure holding jack 25 due to the supply pressure of the concrete, but the pushing piston 24 is Since the pressure holding jack 25 to be pressed is provided with a relief valve that allows the jack to contract when it receives a pressure larger than the set pressure, the pushing piston 24 is provided in front of the shield machine 10 along with the supply of concrete. It does not interfere with the placement of concrete. Further, when the supply of concrete is stopped, the pressing force of the pressure holding jack 25 acts on the pushing piston 24 again and moves backward as the shield machine 10 advances.

(Iii) Excavation process of shield excavator Next, as shown in FIG. 4, the concrete piston chamber 23
While pushing out the concrete of the above, the ground excavation is excavated by the cutter device 12 at the front end of the skin plate 11, and the propulsion jack 13 is driven by taking a reaction force to the formwork 1 to excavate the shield machine 10. This shield machine 10
Cavity K may occur in the ground during excavation. Before the cavity K emerges behind the shield machine 10, the pressure holding jack 25 causes the concrete pressure Po to be higher than the natural pressure Pj, so that there is no risk of water leakage. Further, as the shield machine 10 advances, the cavity K emerges behind the shield machine 10.

Then, as shown in FIG. 5, when the cavity K emerges behind the shield machine 10, part of the footwear material of the footwear wall W moves in the direction of arrow A. When the movement of the footwear material occurs, the pressure of the footwear material in the concrete piston chamber 23 decreases. At this time, the spring provided in the elastic device 70 that takes a short time to expand and contract (has good followability) is stretched due to the decrease in concrete pressure, and the pushing piston 24 is pushed out in the direction of arrow B. By moving the pushing piston 24 in the arrow B direction, the footwear material in the concrete piston chamber 23 moves in the arrow C direction. That is, the footwear material of the shoe wall W moves into the cavity K and refills the cavity K. Here, FIG. 6 shows a state where the cavity K is filled with the footwear material in a short time. In this way, the expansion of the elastic device 70 that takes a short time to expand and contract (has a good followability) makes it possible to fill the cavity K with the footwear material in an extremely short time. Even in this case, the decrease in the pressure of the footwear material can be suppressed within a range that has almost no influence.

The state in which the hollow K is filled with the footwear material will be described in detail below. Concrete pressure P1 in this state
6 is smaller than the initial concrete pressure Po as shown in FIG. 6, but by selecting an elastic material 70 having physical properties (tension, stroke, etc.) suitable for the expected cavity, the cavity K becomes extremely large. Unless it is a large cavity, the concrete pressure P1 can be made larger than the natural pressure Pj. On the other hand, the pressure-holding jack 25 is initially set so that the concrete pressure becomes Po, and therefore extends in the direction of arrow D in FIG. Since the pressure holding jack 25 normally uses a hydraulic jack, this stretching takes a considerable amount of time.

If the cavity K is replenished with concrete only by the pressure-holding jack 25, the pressure-holding jack 25 normally uses a hydraulic jack, so this filling takes a considerable amount of time. Since concrete has a very small elasticity unlike air, if the volume that needs to be filled is larger than the concrete pushing capacity by stretching the pressure holding jack 25, the concrete pressure will drop sharply. Such a sudden decrease in concrete pressure causes the earth and sand and groundwater to be drawn into the work wall W, and the earth and sand and groundwater are mixed into the work material, which causes a serious defect in the quality of the work wall W. Bring

FIG. 7 shows a state in which the pressure holding jack 25 has been stretched and the concrete pressure has reached Po. After this, normal excavation is possible. As described above, since the pressure holding jack 25 and the pushing piston 24 are connected via the elastic device 70, the cavity K
Even if it occurs, it is possible to excavate without lowering the concrete pressure below the natural ground pressure (not possible with a very large cavity).

FIG. 8 shows the intermittent progress of the shield machine 10. Depending on the condition of the ground, the shield machine 10 during excavation may advance intermittently.
Here, when the tail portion instantaneously advances by the distance S,
The footwear material will move in the direction of the arrow F, and as with the appearance of the cavity K, the elastic material 70 is stretched to enable the excavation without lowering the concrete pressure below the ground pressure. Become.

Needless to say, the pressure inside the concrete piston chamber 23 is kept constant by the pressure holding jack 25 even after the completion of the excavation. If it is necessary to replace the seal member 26 of the extrusion piston 24 during the process, the extrusion piston 24 may be removed from the concrete piston chamber 23 after the hardening of the concrete, and the sealing member 26 may be replaced. This work is a simple work of extracting the extruding piston 24 using the pressure holding jack 25 after the concrete is hardened and replacing the seal member 26 on the outer periphery thereof, and since the replacement work is carried out after the concrete is hardened, it can be safely performed on site. Can be done.

When it becomes necessary to clean the concrete pipe, the shut-off mechanism 28 attached to the pushing piston 24 is used to close the filling port 24a, and the placing pipe 3
You can remove 0 and clean it. This work can prevent the concrete from flowing out from the filling hole by the shut-off mechanism 28.
It can be done while applying pressure to the concrete inside, and workability during tunnel lining is not impaired.

In the above-described embodiment, the shield excavator 10 has a double tail portion, a plurality of concrete piston chambers 23 are provided therein, and an extrusion piston 24 is provided in the concrete piston chamber 23.
4 is adapted to adjust the pressure in each concrete piston chamber 23 by the pressure holding jack 2 and the elastic device 70, so that it is possible to cope with a change in natural pressure (usually, the deeper the depth, the higher the pressure). The pressure of the concrete in each room can be individually controlled, and the concrete pressure can always be kept higher than the natural pressure reliably and easily.

Further, the pushing piston 24 is moved to the rear of the shield machine 10 when pushing out concrete, and to the front when putting concrete into the concrete piston chamber 23, and the forward movement is made to the pressure holding jack 2.
5, the pressure holding jack 25 contracts when the driving pressure in the supply pump 31 becomes higher than the holding pressure, so that the concrete piston chamber 23
It becomes possible to keep the concrete pressure of the concrete substantially constant even when it is placed by the supply pump 31, so as not to give an excessive pressure to the ground and the formwork 1 and to push up the ground and the formwork 1 You don't need to be more sturdy than you need. For this reason, it is possible to keep the concrete pressure always higher than the earth pressure and water pressure of the natural ground, preventing water leakage,
High-strength and high-quality concrete can be poured. Further, since the strength due to the hardening of concrete is not required, it is possible to use concrete having a long hardening time, and it is not necessary to clean the pipe or the like for each ring.

Further, in the embodiment, since the concrete piston chamber 23 is provided in the tail portion of the shield machine 10 and the extrusion piston 24 is sealed in the concrete piston chamber 23 and slidably arranged in the factory in advance. , The accuracy of the seal portion of the push-out piston 24 can be maintained at the same level as the seal of the movable portion such as the cutter device 12 of the shield machine 10, and the shield machine 1
Almost all the grounds that can support 0 can be supported.

Further, in the embodiment, since it is possible to safely and easily exchange the seal important for maintaining the pressure of the concrete, the seal can be exchanged even during long-distance excavation so that the concrete pressure can be constantly maintained. It has the advantage that it can be held. Further, in the embodiment, the pushing piston 24 is moved forward with the supply of the concrete, and when the concrete is pushed out, the pushing piston 24 is moved to the rear of the shield machine 10, so that the pressure in the concrete piston chamber 23 is reduced. It is possible to keep it almost constant even when concrete is supplied, and as a result, neither excessive pressure is applied to the ground or the formwork 1, nor the ground is pushed up. This has the effect of eliminating the need to make it sturdy.

Further, according to the above, in the embodiment, the pressure in the concrete piston chamber 23 can always be kept higher than the earth pressure / water pressure of the natural ground, so that there is no water leakage and high strength and high quality concrete. It has the advantage that it can be placed, and since it can reliably fill the tail void, it has the advantage that there is no risk of ground subsidence. Further, in the embodiment, since the pushing piston 24 is configured to constantly press the concrete,
It also enables the use of concrete with a long curing time and eliminates the need to clean the piping and the like for each ring.

Next, a second embodiment of the shield machine of the present invention will be described with reference to FIG. Here, the same components as those in the first embodiment are designated by the same reference numerals to simplify the description. In this shield machine 75, a cylindrical skin plate 11 forming an outer shell and the skin plate 1
A cutter device 12 provided at the front end portion of 1 for excavating the ground by being rotated by a driving means (not shown); and a propulsion jack 13 having a base end connected to a partition plate 11a formed inside the skin plate 11. It has a basic structure equipped with. The tail portion of the skin plate 11 includes an outer cylinder 20 forming a part of the skin plate 11 and the outer cylinder 2
It is formed by a double inner cylinder 21 having a diameter smaller than 0. The outer cylinder 20 and the inner cylinder 21 are connected by a plurality of partition walls 22 extending in the radial direction of the skin plate 11. There is. A plurality of concrete piston chambers 23 are provided between the outer cylinder 20 and the inner cylinder 21, and pushing pistons 24 are slidably housed in the respective concrete piston chambers 23.

The extruding piston 24 is formed in conformity with the internal shape of the concrete piston chamber 23,
A plurality of pressure holding jacks 25 having base ends attached to the partition plate 11a are configured to slide back and forth. The push-out piston 24 and the pressure holding jack 25 form an air damper 76 having a short expansion / contraction operation time.
(Elastic device). This air damper 76, as shown in FIG.
Of the headed cylindrical portions 77 and 78, which are fitted in the axial direction of the headed cylindrical member 77 and 78 so as to be movable back and forth, a space portion 79 formed by butting these headed cylindrical portions 77 and 78, and connected to the space portion 79. , An air tank 80 provided in the concrete piston chamber 23 in front of the pushing piston 24. The heads of the headed cylinders 77 and 78 are connected to the pressure holding jack 25 and the pushing piston 24, respectively, as shown in FIGS. The pressure holding jack 25 that operates the pushing piston 24 is provided with a relief valve, and when the placing pressure of the lining material supply pump 31 becomes higher than the holding pressure of the pressure holding jack 25, The pressure holding jack 25 is configured to contract.

A plurality of (two in the embodiment) seal members 26 are attached to the outer circumference of the extruding piston 24, and the inside of the skin plate 11 and the concrete piston chamber 23 are provided at the center of the extruding piston 24. Is formed with a lining material filling hole 24a that communicates with the lining material, and the filling hole 24a is formed on the inner surface of the extrusion piston 24.
A joint portion 27 is provided which is in communication with a and is connected to the casting pipe 30 of the lining material. Reference numeral 50 is a main gable frame that closes the space between the inner cylinder 21 and the mold 1, and the main gable frame 50 includes a plurality of curved plate bodies corresponding to the curvature of the inner surface of the inner cylinder 21. It has a basic configuration in which it is combined in a ring shape in the longitudinal direction. In the gap between the mold 1 and the main gable frame 50, an auxiliary gable frame 51 that closes the gap is set.

Next, a case of carrying out the shield tunnel lining method by applying the shield machine 75 according to the present invention configured as described above will be described in the order of steps. (I) Placing preparation step When performing concrete pouring to the outside, as in the first embodiment, the pouring pressure of the pressure holding jack 25 is made to correspond to the difference in the ground pressure depending on the height. The concrete is set to a size so that it can always apply a pressure larger than the pressure of the ground, and the driving pipe 30 is connected to the joint portion 27 of the extruding piston 24 through the filling port 24a of the extruding piston 24. The concrete piston chamber 23 is set so that the lining material can be supplied. (Ii) Concrete Placing Step into Concrete Piston Chamber After preparation for concrete pouring is completed, concrete is sent from the supply pump 31 to the pouring pipe 30, and the pouring pipe 3
Concrete is poured into the concrete piston chamber 23 through the filling port 24a of the extrusion piston 24 through 0.

(Iii) Excavation process of shield excavator Next, while pushing the concrete in the concrete piston chamber 23 rearward, the cutter device 12 at the front end of the skin plate 11 excavates the natural ground, and the reaction force is applied to the formwork 1. The shield jack 75 is driven by driving the propulsion jack 13. During the excavation of the shield machine 75, a cavity K may occur in the natural ground. Before the cavity K goes out to the rear of the shield machine 75, the concrete pressure Po is higher than the natural pressure Pj by the pressure holding jack 25, so that there is no fear of water leakage. Furthermore, as the shield machine 75 advances, the cavity K emerges behind the shield machine 75.

Then, as shown in FIG. 5, when the cavity K emerges behind the shield machine 75, a part of the footwear material of the footwear wall W moves in the direction of arrow A. When the movement of the footwear material occurs, the pressure of the footwear material in the concrete piston chamber 23 decreases. At this time, the air damper 76 (resilient device), which takes a short time to expand and contract (has good followability), stretches due to the decrease in the pressure of the concrete, and the arrow B
The pushing piston 24 is extruded in the direction of. By moving the pushing piston 24 in the arrow B direction, the footwear material in the concrete piston chamber 23 moves in the arrow C direction. That is, the footwear material of the footwear wall W moves into the cavity K,
Refill the cavity K.

The action of the air damper 76 for preventing a sudden pressure drop will be described. According to the air damper 76, the pressure fluctuation can be suppressed to be much smaller than that in the first embodiment. That is, according to the air damper 76, the following relationship is established according to Boyle's law. Po * Vo = P1 * (Vo + [Delta] V) (1) P1 = {Vo / (Vo + [Delta] V)} * Po ... (2) where Po is the set pressure of the pressure holding jack 25, and Vo is the pressure holding jack. When the pressure of 25 is Po, the total amount of air in the air damper 76 is represented, ΔV represents the amount of air required to push out the pushing piston 24 by the air damper 76 in an emergency, and P1 indicates the amount of the pushing piston 24 in an emergency. The pressure of the air damper 76 after being pushed out is shown.

From (1) and (2), if Vo is made sufficiently larger than ΔV, the amount of pressure drop can be reduced and concrete can be poured. For example, Vo
If ΔV is set to 10 times ΔV, and 0.1V is applied to ΔV in the equation (2), the result is as follows. P1 = {Vo / (Vo + 0.1Vo)} × Po (3) ∴P1 = (1 / 1.1) × Po = 0.91Po (4) If Vo is set to 100 times ΔV, the formula is ΔV of (2)
Applying 0.01 Vo to the following results in: P1 = (1 / 1.01) × Po = 0.99Po ... (5)

As described above, by increasing the total air amount Vo of the air damper 76, the fluctuation between the pressure P1 of the air damper 76 after the pushing piston 24 is pushed out and the set pressure Po of the pressure holding jack 25 is extremely small. It is possible to suppress. Further, in order to increase the total air amount Vo of the air damper 76, the air tank 80 may be enlarged. Air tank 8 near this air damper 76
When there is no place to install 0, as shown in FIG. 12, an air tank 80 is provided in a wide place apart from the concrete piston chamber 23, and the air tank 80 and the space 79 of the air damper 76 are connected, for example, flexible. A different pipe 82 may be provided.

In such a shield machine 75, the tail portion of the shield machine 10 is doubled, a plurality of concrete piston chambers 23 are provided therein, and an extrusion piston 24 is provided in the concrete piston chamber 23. The pressure holding jack 2 and the air damper 76 are used to further improve the followability of the pushing piston 24 as compared with the first embodiment, and the pressure inside each concrete piston chamber 23 is adjusted. Therefore, in addition to having the same effect as that of the first embodiment, when the cavity K is provided in the natural ground, the shield machine 75
Even if the pressure progresses intermittently, the concrete pressure in each room can be managed individually in response to changes in the ground pressure (usually, the deeper the depth, the higher the pressure). It is possible to reliably and easily keep the pressure higher than the natural pressure.

[0048]

As described above, the shield machine according to the first aspect of the invention has the following effects. Since the pressure-holding jack and the push-out piston are connected via an elastic device, the push-out piston can be pushed out quickly when the shield machine progresses intermittently or there is a hollow in the ground, resulting in a sudden pressure drop. Can be prevented, and then the predetermined pressure can be held by extending the pressure holding jack. Since the concrete piston chamber is provided by forming the partition wall, a plurality of concrete piston chambers can be manufactured in advance in a factory or the like.
For this reason, the concrete piston chamber can be manufactured with high precision, a seal that can withstand high pressure can be manufactured, and the extrusion piston can be safely removed from the concrete piston chamber after hardening the concrete. Can be facilitated. By controlling the pressures of the extrusion pistons in the concrete piston chambers formed in these tails individually with the pressure-retaining jacks, the pressure of the footwear material in each chamber can be controlled individually. The difference in mountain pressure can be easily dealt with, and the pressure of the footwear material can always be kept higher than the earth pressure and water pressure of the natural ground.
Further, by such an action, the tail void is surely filled with the footwear material, and the risk of sinking is eliminated. Further, when the supply pressure of the footwear material becomes larger than the set holding pressure of the pressure holding jack, the supply pressure of the footwear material is configured to move the pushing piston forward of the shield machine. The extrusion piston moves to the rear of the shield machine when pushing the footwear material and to the front when putting the footwear material into the piston chamber, so that the pressure inside the concrete piston chamber can be kept almost constant even when the footwear material is supplied. It will be possible. Therefore, even if the shield machine is intermittently advanced or even if there are cavities in the ground, it is possible to sufficiently maintain the pressure and reliably prevent the pressure from decreasing, and there is no water leakage. High-strength, high-quality lining material can be placed, the shield tunnel can be constructed quickly and safely, and the ground is pushed up without giving excessive pressure to the ground and the formwork. And without having to make the form more robust than necessary.

According to the shield machine of claim 2,
In addition to the effect according to claim 1, since the pressure holding jack and the pushing piston are connected through the elastic device, and the elastic device is provided with the spring, the shield machine can be intermittently advanced, If there are cavities in the ground,
A spring that takes a short time to expand and contract (good followability) stretches due to the decrease in concrete pressure, quickly pushes out the extrusion piston, prevents a sudden decrease in pressure, and then retains a predetermined pressure by extending the pressure holding jack can do. For this reason, the intermittent progress of the shield machine,
Even if there are cavities in the ground, the pressure can be sufficiently retained to reliably prevent the pressure from decreasing, and there is no water leakage, and high-strength, high-quality lining material can be placed. This makes it possible to construct shield tunnels quickly and safely, without giving excessive pressure to the ground or formwork, without pushing up the ground, and making the formwork stronger than necessary. You can eliminate the need to

According to the shield machine of claim 3,
In addition to the effect according to claim 1, the pressure holding jack and the pushing piston are connected via the elastic device, and the elastic device is provided with the air damper, so that the shield machine can be intermittently advanced or , When there is a cavity in the ground, the air damper stretches due to the decrease in concrete pressure, quickly pushes out the extrusion piston to prevent a sudden drop in pressure, and then stretches the pressure holding jack to maintain a predetermined pressure. be able to. Here, by the air damper, it is possible to suppress the fluctuation between the pressure of the air damper after pushing out the pushing piston and the set pressure of the pressure holding jack to be very small. For this reason,
Even in the case where the shield machine is intermittently advanced or there are cavities in the ground, it is possible to sufficiently retain the pressure as compared with the shield machine according to claim 2 and surely prevent the pressure from decreasing. In addition, it is possible to place high-quality and high-quality lining material without water leakage, which enables quick and safe construction of shield tunnels and gives excessive pressure to the ground and formwork. It eliminates the need to push the ground up, and eliminates the need to make the form more robust than necessary.

[Brief description of drawings]

FIG. 1 is a side sectional view of a tunnel showing a state in which a shield machine is excavating a natural ground in a first embodiment of the shield machine of the present invention.

FIG. 2 is a cross-sectional view taken along the line I-I of FIG.

FIG. 3 is a process diagram showing a process of placing concrete into the reinforcing bar assembly chamber of FIG.

FIG. 4 is a side sectional view showing the pushing piston of FIG.

5 is a side sectional view before the cavity of FIG. 4 is filled with the footwear material.

6 is a side cross-sectional view of the cavity of FIG. 5 when the footwear material is filled.

7 is a side cross-sectional view after the cavity of FIG. 6 has been filled with footwear material.

FIG. 8 is a side sectional view showing an intermittently advanced state of the shield machine of FIG. 1.

FIG. 9 is a side sectional view showing an extruding piston in a second embodiment of the shield machine of the present invention.

10 is a side sectional view showing the air damper of FIG.

11 is a cross-sectional view of FIG.

FIG. 12 is a side sectional view showing the air tank of the air damper of FIG. 9 installed at another position.

[Explanation of symbols]

 T tunnel 1 formwork 10 shield machine 11 skin plate 12 cutter device 13 propulsion jack 20 outer cylinder 21 inner cylinder 22 partition wall 23 concrete piston chamber 24 extrusion piston 25 pressure holding jack 50 main gable frame 51 auxiliary gable frame 70 elastic device 76 air Damper

(72) Inventor Hidetake Ishizaki 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Shinichi Nishimura 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Masayuki Otsuka 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Tayoshi Taichi 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Invention Minor Imai 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Toru Kawai 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd.

Claims (3)

[Claims] 1. A cylindrical skin plate forming an outer shell,
A cutter device for excavating the ground by being rotated by a driving means provided at the front end portion of the skin plate, and a propulsion jack having a base end connected to a partition plate formed inside the skin plate were provided. In the shield machine, the tail portion of the skin plate is double formed by an outer cylinder and an inner cylinder, and a plurality of partition walls extending in the radial direction of the skin plate are formed between the inner cylinder and the outer cylinder of the tail portion. A plurality of concrete piston chambers for accommodating the pushing pistons are provided, the pushing pistons are inserted into the concrete piston chambers, a plurality of pressure holding jacks are provided on the partition plate, and the pressure holding jacks and the pushing pistons are elastic. A shield machine, which is connected through a device. 2. The shield machine according to claim 1, wherein the elastic device is provided with a spring. 3. The shield machine according to claim 1, wherein the elastic device is provided with an air damper.