JP2023121407A - Insulation structure of frozen duct, segment and freezing method - Google Patents

Abstract

To make cold from a frozen duct conduct to a frozen object more effectively by taking an insulation measure with a high insulation property compared to a conventional insulation material such as urethane foam to a freezing method.SOLUTION: An insulation structure of a frozen duct 18 comprises a concrete wall 14, a skin plate 12 to cover an outer surface of the concrete wall 14, a recess part 24 formed at the outer surface of the concrete wall 14, a frozen duct 18 laid on an inner surface of the skin plate 12 within the recess part 24, and a vacuum insulation layer 34 formed between the inner surface of the skin plate 12 and an inner surface of the recess part 24.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a technique for freezing soil or the like by circulating a refrigerant in a freezing pipe, stabilizing the ground, stopping water, or the like.

When a tunnel is formed in the ground by the shield construction method, a shield machine is started from a starting pit formed in the ground, and a tunnel is excavated toward the arrival pit. When the tunnel formed by the shield machine is connected to the arrival shaft, frozen soil may be formed in the surrounding soil for the purpose of stabilizing the ground and stopping water.

For example, in Patent Document 1, a plurality of frozen pipes are attached to the inside of a steel segment (filled concrete) that constitutes the wall of a tunnel built in the ground, and a refrigerant such as brine is circulated in each frozen pipe. A technique is disclosed for freezing the soil outside the steel segment by allowing the soil to freeze.
JP 2017-101452

In the case of the steel segment of Patent Document 1, each frozen pipe is covered with a covering material such as concrete or mortar, and the surface is covered with a heat insulating layer, so that cold heat from the frozen pipe is efficiently transmitted to the soil. are planning to
That is, according to the document, since concrete and mortar have excellent heat storage properties, by covering each freezing tube with these, it is possible to cool the soil in a plane rather than in a point or line. It is said that the heat insulating layer can effectively prevent cold heat from dissipating into the tunnel.

However, since the heat insulating layer is made of urethane foam, its heat insulating performance is limited.
This invention has been devised in view of the current situation. The purpose is to provide a technology that can efficiently conduct the cold heat from the freezer to the frozen object.

In order to achieve the above object, the heat insulation structure for a frozen tube according to claim 1 comprises an inner stuffing material, an exterior material covering the outer surface of the inner stuffing material, and a concave portion formed on the outer surface of the inner stuffing material. a freezing pipe laid on the inner surface of the exterior material in the recess; and a vacuum heat insulating layer formed between the inner surface of the exterior material and the interior surface of the recess.

A heat insulating structure for a frozen tube according to claim 2 is the structure according to claim 1, wherein a rib that supports the recess is provided in the recess, and the rib is provided with each of the ribs partitioned by the rib. It is characterized in that a channel is formed in the void for circulating gas, liquid, or semi-fluid.

The segment described in claim 3 is a segment used in a shield construction method, comprising a concrete wall having a curved shape, a metal plate having a curved shape covering the outer surface of the concrete wall, and a metal plate having a curved shape covering the outer surface of the concrete wall a formed recess, a freezing tube attached to the inner surface of the metal plate and housed in the recess, a conduit for circulating and supplying a refrigerant to the freezing tube, an inner surface of the recess and the freezing tube and a conduit for discharging air in a gap existing between the surface of the body and the surface of the body.

The segment according to claim 4 is the segment according to claim 3, wherein ribs are provided in the recesses to support the recesses, and the ribs are provided with gas and gas in the gaps partitioned by the ribs. It is characterized in that a channel is formed for circulating a liquid or a semi-fluid.

The freezing method according to claim 5 comprises: an inner stuffing material, an exterior material covering the outer surface of the inner stuffing material, a recess formed in the outer surface of the inner stuffing material, and an inner surface of the exterior material in the recess A freezing method using a filling structure including a laid freezing pipe and a vacuum insulation layer formed between the inner surface of the exterior material and the inner surface of the recess, wherein the inner surface of the recess and the freezing Forming a vacuum insulation layer by discharging the air in the gap between the surface of the pipe and supplying a refrigerant to the frozen pipe to form frozen soil in the soil in contact with the filling structure from It is characterized by becoming

The freezing method according to claim 6 is the method according to claim 5, wherein ribs are provided in the recesses to support the freezing pipes, and the ribs have gaps partitioned by the ribs. It is characterized by forming a channel for circulating a liquid or a semi-fluid.

The freezing method described in claim 7 includes the steps of connecting a bottomed cylindrical steel receiving chamber to the metal plate forming the inner surface of the arrival shaft, and attaching a freezing pipe to the outer surface of the steel receiving chamber. a step of injecting a filling material between a shield tunnel connected to the shield machine and an opening of the arrival shaft when the shield machine enters the steel receiving chamber by excavating the arrival shaft; forming a vacuum insulation layer by discharging the air in the gap formed between the inner surface of the exterior body and the surface of the freezing tube; and supplying the refrigerant to the freezing tube. and a step of circulating and supplying the filler to freeze the filler.

The freezing method according to claim 8 is the method according to claims 5 to 7, characterized in that the filling material is injected into the gap and the frozen pipe after the maintenance of freezing is no longer necessary.

According to this invention, since a vacuum insulation layer with high heat insulating properties is formed around the frozen pipe, heat conduction to anything other than the frozen object is prevented, and cold heat from the frozen pipe is wastefully conducted to the concrete wall or the like. is suppressed to the utmost limit, and cold heat can be efficiently conducted to a frozen object such as soil.
As a result, the time required for freezing can be shortened and the quality of freezing can be improved.

It is a figure explaining the principle of the ground freezing construction method based on this invention using the freezing pipe of a flat perforated pipe type. FIG. 10 is a diagram showing a state in which a filler is injected into the voids and frozen tubes that constitute the vacuum insulation layer; FIG. 2 is a diagram explaining the principle of the ground freezing method according to the present invention using a cylindrical freezing pipe having a single pipe structure; FIG. 6 is a cross-sectional view taken along line AA of FIG. 5 showing an example in which the present invention is applied to a segment of the shield construction method; FIG. 4 is a plan view showing a state in which the skin plate of the segment is removed; It is a figure which shows the example which applied this invention in an arrival shaft. FIG. 10 is a view showing an armor body formed on the outer peripheral surface of the steel receiving chamber in the arrival shaft;

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram for explaining the principle of the freezing method according to the present invention. A filling structure, that is, a skin plate 12 as an exterior material and a comparative It is depicted as being supported by a concrete wall 14 as a thick filling material.
An internal space 16 is formed below the concrete wall 14 .
The skin plate 12 is made of a metal plate such as steel plate or stainless steel plate.

A freezing pipe 18 is attached to the lower side of the skin plate 12, and its periphery is covered with a filling material 20 made of concrete or mortar.
The freezing tube 18 has a flat, flat perforated tube structure in which a plurality of micro refrigerant channels 22 having a rectangular cross section are horizontally connected, and liquefied carbon dioxide or the like as a refrigerant is circulated in each micro refrigerant channel 22. be.

A recess 24 is formed in the outer surface of the concrete wall 14, and the frozen pipe 18 and the filling material 20 are accommodated in this recess 24. As shown in FIG.
A gap 26 is formed between the recess 24 and the skin plate 12 and the filler material 20 .
A plurality of ribs 28 are arranged in the gap 26 at predetermined intervals.
Some ribs 28 are interposed between the bottom surface of the recess 24 and the filler 20, and other ribs 28 are interposed between the bottom surface of the recess 24 and the inner surface of the skin plate 12. .
Each rib 28 is arranged to support the recess 24 against the pressure from the soil and the vacuum negative pressure described below.
Each rib 28 is provided with a through-hole 30 as a flow path to ensure lateral flow of gas, liquid, and semi-fluid.

A pipe (pipe line) 32 is inserted through the concrete wall 14, and its tip opening 32a is led out into the gap 26. As shown in FIG. Further, the rear end opening 32b protrudes into the internal space 16. As shown in FIG.

Next, the ground freezing process will be explained.
First, an air hose, a valve, and a vacuum pump (not shown) are connected to the rear end opening 32b of the pipe 32, the air in the gap 26 is sucked into a vacuum state, and then the valve is closed. As a result, the voids 26 constitute the vacuum heat insulating layer 34 .
As described above, each rib 28 arranged in the gap 26 is formed with the through hole 30, so that every corner of the gap 26 is in a vacuum state.

Next, the frozen soil 36 is formed in the soil 10 by circulating the refrigerant through the minute refrigerant flow paths 22 of the freezing pipes 18 via piping (not shown). As a result, since the soil 10 is stabilized and the water cut-off property is ensured, it is possible to safely carry out various construction works (for example, construction of connecting a shield tunnel and an arrival vertical shaft, etc.).

Since the vacuum insulation layer 34 is formed between the freezing pipe 18 and the filling material 20 and the concrete wall 14 as described above, cold heat from the freezing pipe 18 does not escape to the concrete wall 14 side. Most of it is conducted through the skin plate 12 to the soil 10 to be frozen. As a result, the formation of the frozen soil 36 is realized extremely efficiently.
Incidentally, the insulation performance (thermal conductivity) of the vacuum insulation layer 34 is approximately 0.002 W/m K, which surpasses the insulation performance (approximately 0.024 W/m K) of rigid urethane foam, which is a general insulation material. ing.

When the necessary construction work is completed and the maintenance of the frozen soil 36 is no longer necessary, the valve is opened to release the vacuum state, instead, a mortar hose is connected to the rear end opening 32b of the pipe 32, and the mortar pump is used to remove the vacuum. Filling materials such as shrinkable mortar are pumped.
As a result, as shown in FIG. 2, the filling material 40 spreads within the voids 26 and the pipes 32 .
Also, a filling material 40 such as non-shrinkable mortar is injected into each minute refrigerant channel 22 of the freezing tube 18 through a pipe (not shown) in place of the refrigerant.

In this way, since the filler 40 is placed in the voids 26, the pipes 32, and the frozen pipes 18 after the construction work is completed, no gaps are left in the concrete structure, and a predetermined strength can be secured.

Incidentally, since it is not allowed to leave foreign matter in the concrete wall 14, which is a permanent structure, it is not possible to place a conventional heat insulating material made of hard urethane foam or the like instead of the vacuum heat insulating layer 34 in this place.
In addition, even if cold heat can be prevented from dissipating into the internal space 16 with the conventional measure of attaching a heat insulating material to the inner surface of the concrete wall 14 (the boundary portion with the internal space 16), the thickness of the concrete wall 14 When the is relatively thick, losses due to diffusion of cold into the concrete become non-negligible.

In the above, an example using a flat porous tube type freezing tube 18 was shown, but as shown in FIG. 3, the present invention is also applicable to a freezing method using a cylindrical freezing tube 42 having a single tube structure It is possible.
Also in this case, the outer peripheral surface of the freezing tube 42 is in contact with the inner surface of the skin plate 12, and the periphery thereof is covered with the filling material 20. As shown in FIG.
A gap 26 is formed between the recess 24 formed on the outer surface of the concrete wall 14 and the filling material 20, and a plurality of ribs 28 having through holes 30 are arranged at predetermined intervals.

Then, air is sucked into the space 26 through the pipe 32 inserted through the concrete wall 14 to form the vacuum heat insulating layer 34, the valve is closed, and a refrigerant such as brine (antifreeze) is introduced into the freezing pipe 42. The circulation forms frozen soil 36 within the soil 10 .

Similar to the above, since the vacuum insulation layer 34 is formed between the freezing pipe 42 and the filling material 20 and the concrete wall 14, the cold heat from the freezing pipe 42 does not escape to the concrete wall 14, and most of it It is conducted to the soil 10 to be frozen through the skin plate 12 .

Although not shown, in this case as well, when the necessary construction work is completed and the maintenance of the frozen soil 36 is no longer necessary, the valve is opened to release the vacuum state, and instead, the rear end opening 32b of the pipe 32 is closed. A hose for supplying a filler such as mortar is connected, and the filler is supplied to the gap 26 by a mortar pump.
A filling material is also supplied to the inside of the freezing tube 42 instead of the refrigerant.

FIG. 4 shows an embodiment in which a frozen pipe 52 and a filling material 54 are placed in a segment 50 used in the shield construction method, and a vacuum insulation layer 56 is formed around them.
The segment 50 has a curved cross-sectional shape, and by connecting the end surfaces of a plurality of segments 50, an annular inner wall surface of the tunnel is formed. Therefore, the skin plate 58 and the concrete wall 60 also have cross-sectional curved shapes.

A flat perforated tube type freezing tube 52 is attached to the inner surface of the skin plate 58 , and the surface of the freezing tube 52 is covered with a filling material 54 . A cylindrical freezing tube may be used instead of the flat perforated tube type freezing tube 52 .
A concave portion 62 having a curved cross section is formed on the outer surface of the concrete wall 60, and the frozen pipe 52 and the filling material 54 are housed therein.
A space 64 that functions as a vacuum heat insulating layer 56 is formed between the recess 62 and the filler 54 .
Furthermore, a plurality of ribs 70 having through holes 66 are interposed within the recess 62 at predetermined intervals.
Reference numeral 72 in the drawing indicates a pipe that is connected to the gap 64 for communication.

FIG. 5 is a plan view of the segment 50 showing the removal of the skin plate 58 from the concrete wall 60. FIG.
As shown in the figure, a recess 62 is formed on the outer surface of the concrete wall 60, and a plurality of ribs 70 are erected at predetermined intervals on the bottom surface of the recess.
Further, a freeze tube 52 that meanders back and forth in the left and right direction is attached to the inner surface of the skin plate 58, and its surface is covered with a filling material 54. As shown in FIG.
Reference numerals 76a and 76b in the drawing denote through holes through which refrigerant flow pipes 78a and 78b connected to both ends of the freezing pipe 52 are inserted.

A plurality of segments 50 are installed on the inner wall surface of a tunnel excavated by a shield machine (not shown), and the end faces of adjacent segments are connected to each other.
Then, the air in the gap 64 of each segment 50 is sucked through the pipe 72 to form a vacuum insulation layer 56 between the filling material 54 covering the freezing pipe 52 and the concrete wall 60 .
Here, when the refrigerant is circulated and supplied to each of the freezing pipes 52 through the refrigerant circulation pipes 78a and 78b, the soil in contact with the outer surface of the skin plate 58 is cooled, and an annular frozen soil is formed at the connection with the arrival shaft. It is formed. As a result, soil stability and water stoppage are ensured at the connection with the arrival shaft.

After the necessary construction work is completed and it is no longer necessary to maintain the frozen soil, the vacuum state of the gaps 64 forming the vacuum insulation layer 56 is released, and the filling material is supplied through the pipes 72 to fill the gaps. 64 is filled.
At the same time, the filling material is also supplied into the freezing pipe 52 through the refrigerant flow pipes 78a and 78b.

FIG. 6 shows an embodiment for applying the invention in an access shaft 80. As shown in FIG.
That is, before the shield machine 82 reaches the arrival pit 80, a cylindrical steel receiving chamber 84 is attached by welding to the skin plate 83 forming the inner peripheral surface of the arrival pit 80 as preparation for receiving.
Next, after the shield machine 82 drills the wall surface of the arrival shaft 80 and enters the steel receiving chamber 84, the shield machine 82 is dismantled.

When dismantling the shield machine 82, in order to prevent groundwater and earth from flowing into the arrival shaft 80, a filler 85 made of cement bentonite or the like is injected into the gap between the shield machine 82 and the steel receiving chamber 84. , freezing this filling material 85 is performed.

In this freezing work, conventionally, a heat insulating material made of hard urethane foam or the like is placed behind the freezing pipe 87 and the filling material 88 wound around the outer peripheral surface of the steel receiving chamber 84, so that the cold heat from the freezing pipe 87 is dissipated. It was prevented from dissipating into the arrival shaft 80.
In contrast, in this embodiment, by providing the vacuum heat insulating layer 89, a higher heat insulating effect is realized.

The vacuum heat insulating layer 89 described above is formed by the following steps.
(1) A plurality of freezing pipes 87 are attached in an annular shape to the outer peripheral surface of the steel receiving chamber 84, and the outer periphery thereof is covered with a filling material 88.
(2) A formwork (not shown) is provided on the outer peripheral surface of the steel receiving chamber 84 and concrete is placed to form the exterior body 90 that airtightly surrounds the frozen pipe 87 and the filling material 88 . At this time, a gap 91 is formed between the inner surface of the exterior body 90 , the surface of the filling material 88 , the outer peripheral surface of the steel receiving chamber 84 and the skin plate 83 .
(3) Evacuate the air in the gap 91 through the pipe 92 inserted through the exterior body 90 to form the vacuum heat insulating layer 89 .

As shown in FIG. 7, the exterior body 90 is based on the shape of a bottomed cylindrical body laid down sideways. An end surface 94 that contacts the skin plate 83 has a curved shape corresponding to the inner peripheral surface of the skin plate 83 .
Although not shown, it also has an opening for leading the end of the freezing tube 87 to the outside.

After the vacuum insulation layer 89 is formed behind the freezing pipe 87 as described above, by circulating and supplying the refrigerant to the freezing pipe 87, cold heat is conducted to the inner peripheral surface of the steel receiving chamber 84, and the shield machine 82 The filler material 85 between is frozen.
As a result, it is possible to effectively prevent earth and sand or groundwater from flowing into the arrival shaft 80 from the natural ground side.
As described above, the vacuum heat insulating layer 89 has much higher heat insulating performance than heat insulating materials such as rigid urethane foam, so the time required for freezing can be greatly shortened.

In the above, an example in which a part of the vacuum heat insulating layer 89 (the voids 91) is constituted by the skin plate 83 is shown, but by forming the shape of the exterior body 90 to have, for example, a letter-shaped cross section, the exterior body 90 can be A gap 91 may be formed between the inner surface, the surface of the filling material 88 and the outer peripheral surface of the steel receiving chamber 84 .

10 Soil
12 skin plate
14 concrete wall
16 Interior space
18 cryo tube
20 filler
22 micro coolant channels
24 recess
26 Gap
28 ribs
30 through hole
32 Pipe
34 Vacuum insulation layer
36 Frozen soil
40 filler
42 Cryo Tube
50 segments
52 Cryo Tube
54 Filling material
56 Vacuum insulation layer
58 segment skin plate
60 concrete wall
62 recess
64 void
66 through hole
70 ribs
72 Pipe
80 Arrival Shaft
81 Shield Tunnel
82 Shield Machine
83 Skin plate of arrival shaft
84 Steel Receiving Room
85 Filler
86 Pit
87 Freezing tube
88 Filling material
89 Vacuum insulation layer
90 Exterior body
91 void
92 Pipe

Claims (8)

filling material;
an exterior material that covers the outer surface of the filling material;
a concave portion formed on the outer surface of the filling material;
a freezing pipe laid on the inner surface of the exterior material in the recess;
a vacuum heat insulating layer formed between the inner surface of the exterior material and the inner surface of the recess;
Insulation structure of freezing tube with A rib that supports the recess is provided in the recess,
2. The heat insulation structure of a freezing tube according to claim 1, wherein the ribs are formed with flow paths. A segment used in the shield construction method,
a concrete wall with a curved shape;
a metal plate having a curved shape that covers the outer surface of the concrete wall;
a recess formed in the outer surface of the concrete wall;
a freezing tube attached to the inner surface of the metal plate and housed in the recess;
a conduit for circulating and supplying a refrigerant to the freezing pipe;
a conduit for discharging air in a gap existing between the inner surface of the recess and the surface of the freezing tube to the outside;
segment with . A rib that supports the recess is provided in the recess,
4. The segment according to claim 3, wherein said ribs are formed with channels. an inner stuffing material, an outer material covering the outer surface of the inner stuffing material, a recess formed in the outer surface of the inner stuffing material, a freezing pipe laid on the inner surface of the outer material in the recess, and the outer material A freezing method using a filling structure having a vacuum insulation layer formed between the inner surface of the recess and the inner surface of the recess,
forming a vacuum heat insulating layer by discharging the air in the gap between the inner surface of the recess and the surface of the freezing tube;
a step of supplying a refrigerant to the freezing pipe to form frozen soil in the soil in contact with the exterior material;
Freezing method consisting of. A rib that supports the recess is provided in the recess,
6. The freezing method according to claim 5, wherein the rib is formed with a channel. connecting a bottomed cylindrical steel receiving chamber to a metal plate forming the inner surface of the arrival shaft;
affixing a freezing tube to the outer surface of the steel receiving chamber;
a step of injecting a filling material between a shield tunnel leading to the shield machine and an opening of the arrival shaft when the arrival shaft is excavated and the shield machine enters the steel receiving chamber;
a step of forming an armor covering the freezing tube;
a step of discharging air from a gap formed between the inner surface of the exterior body and the surface of the freezing tube to form a vacuum heat insulating layer;
a step of circulating and supplying a refrigerant to the freezing tube to freeze the filling material;
Freezing method consisting of. The freezing method according to any one of claims 5 to 7, characterized in that a filling material is injected into the gap and the freezing pipe after the maintenance of freezing becomes unnecessary.

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