JP2010265631A - Freezing pipe unit, freezing device and freezing method using freezing pipe unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To permit the works of reinforcing and repairing an underground structure safely and at a low cost to be carried out while reducing an influence on the ground around. <P>SOLUTION: When the ground 2 outside the underground structure 3 is to be frozen, a freezing pipe unit 22 made by connecting a plurality of freezing pipes 10 each having an inlet and an outlet of a refrigerant and having a structure where the refrigerant inpoured from the inlet of one of the freezing pipes 10 is discharged from the outlet of another freezing pipe 10 through the freezing pipes 10 is used. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a freezing tube unit for flowing a refrigerant, a freezing apparatus including the freezing tube unit, and a freezing method using the freezing tube unit.

  In the construction to reinforce or renovate existing small underground structures such as manholes by drilling or opening, water flows into the underground structure from the ground around the underground structure, or the surrounding ground is It is necessary to effectively prevent the collapse. A chemical solution injection method is known as one of ground improvement methods that can meet such demands (see, for example, Patent Document 1).

  The chemical solution injection method is a method of injecting a liquid material in which a hardening agent and an auxiliary agent are added to a water glass-based chemical solution (main agent) into the ground around the underground structure to cure the ground. This is a method to reduce and strengthen the ground.

  Moreover, the freezing method is also known as another ground improvement method (for example, refer patent document 2). The freezing method is a method in which a ground to be hardened is excavated to form a hole, and a freezing pipe for injecting a refrigerant into the hole is buried in the ground.

JP-A-5-311637 (abstract) JP 2004-176447 A (Claims etc.)

  However, in the case of the chemical solution injection method and the freezing method described above, it is necessary to grasp the soil condition of the surrounding ground, and the investigation for that is expensive. In addition, since the boring from the ground is required in order to inject the chemical solution and the refrigerant into the ground, the cost of the construction becomes high. For this reason, in practice, in order to reduce the construction cost, it is often the case that chemical solution is injected in a coping therapy after inundation from the surrounding ground or collapse of the ground occurs. Such coping therapy has a problem of increasing the risk of construction. In particular, in the case of the chemical solution injection method, there is a concern about the adverse effect on the surrounding ground, and the construction cost including the countermeasures becomes high.

  The present invention has been made to solve the above-mentioned problems, and it is intended to reduce the influence on the surrounding ground, and to perform construction such as reinforcement and renovation of underground structures safely and at low cost. With the goal.

  In order to achieve the above-described object, a cryopipe unit of the present invention is formed by connecting a plurality of cryotubes having refrigerant inlets and outlets, and a plurality of refrigerants injected from the inlet of a single cryotube. It has a structure that is discharged from the discharge port of another freezing tube through the freezing tube.

  Further, another cryopipe unit of the present invention is formed by arranging two or more cryopipes along the inner surface of an underground structure, and a frame shape or a frame for fixing the two or more freeze tubes on the inner surface. And a split-piece-like fixing member forming a part of the above.

  Further, another freezing pipe unit of the present invention further includes one or a plurality of buried freezing pipes that can be inserted into the ground outside from the inner surface of the underground structure and can supply a refrigerant.

  The freezing apparatus of the present invention is formed by connecting a plurality of cryotubes having refrigerant inlets and outlets, and refrigerant injected from one cryotube inlet passes through one or more cryotubes, A temperature sensor including a freezing tube unit having a structure that is discharged from a discharge port of another freezing tube, and disposed on the surface of the freezing tube through which the refrigerant flows (for example, disposed on the freezing tube surface on the inner surface of the manhole); And a control device for controlling the opening / closing operation of the valve based on temperature information detected by the temperature sensor, and the control device is configured to control the temperature when the temperature is smaller than a predetermined value. The valve operation is controlled so that the valve is closed and the valve is opened when the temperature is equal to or higher than the predetermined value.

  Here, the opening / closing operation of the valve includes not only the case where the valve is completely opened or closed, but also the case where the degree of opening of the valve is changed to adjust the flow rate of the refrigerant and the valve is not completely opened or closed. As such, it shall be interpreted broadly. Hereinafter, the same applies to the control of the valve opening / closing operation.

  In the freezing method of the present invention, a plurality of freezing pipes having refrigerant inlets and outlets are connected, arranged along the inner surface of the underground structure, and the refrigerant is supplied from the inlet of one freezing pipe. Supply and discharge the refrigerant from the outlet of another freezing pipe, and the refrigerant flowing through multiple freezing pipes exchanges heat with the outer ground via the outer wall of the freezing pipe and the inner surface of the underground structure. And freeze the ground outside the underground structure.

  In another freezing method according to the present invention, in the step of arranging a plurality of freezing pipes along the inner surface of the underground structure, a clogging member is interposed in the gap between the freezing pipe and the inner surface.

  In addition, another freezing method according to the present invention has a provision for disposing a water stop plug on the upstream side and the downstream side of the drain pipe when the drain pipe passes through the underground structure, and temporarily passing through the two water stop plugs. Install the piping and place the freezing pipe so as to avoid the temporary piping.

  Another freezing method according to the present invention is based on temperature information detected by a temperature sensor disposed on the surface of the freezing tube through which the refrigerant flows (for example, disposed on the surface of the freezing tube on the inner surface of the manhole). A control method for controlling the opening and closing operation of the valve provided in the supply path, so that the valve is closed when the temperature is lower than a predetermined value set in advance, and the valve is opened when the temperature is higher than the predetermined value. Control the operation of the valve.

  According to the present invention, it is possible to reduce the influence on the surrounding ground, and to perform construction such as reinforcement and repair of an underground structure safely and at low cost.

FIG. 1 is an overall configuration diagram for explaining a situation in which a freezing apparatus according to an embodiment of the present invention is set inside an underground structure and the ground around the underground structure is frozen. FIG. 2 is a view of a state where the freezing apparatus according to the embodiment of the present invention is fixed to the inner side of the manhole when viewed from the opening side (the ground surface side) of the manhole, and a partially enlarged view thereof. FIG. 3 is a cross-sectional view showing the internal structure of the freezing tube. FIG. 4 is a diagram illustrating a state in which a fixing metal fitting, which is a partial configuration of the freezing device, is carried into the manhole. FIG. 5 is a diagram illustrating the fixing bracket in a state where the half-shaped fixing bracket is joined. FIG. 6 is a perspective view showing a state in which each freezing tube is fixed to the inner surface of the manhole with a fixing bracket. FIG. 7 is a diagram showing a state in which the inside of the manhole is virtually expanded left and right, and the freezing tubes fixed on the inside are arranged in the left-right direction. FIG. 8 illustrates a control device constituting a part of the freezing device, and a method for controlling the opening / closing operation of the valve based on the signals of the valves in the liquid nitrogen supply path and the thermocouple installed on the surface of the freezing tube. FIG. FIG. 9 is an overall configuration diagram (9A) showing a modified example of the freezing apparatus according to the present invention and a simplified diagram (9B) showing a state when a part thereof is viewed from the direction of arrow A.

  Next, preferred embodiments of the present invention will be described with reference to the drawings. Hereinafter, an example in which a freezing device is fixed inside a manhole (an example of an underground structure) buried underground and the ground around the outside of the manhole is frozen, the cryopipe unit according to the embodiment of the present invention, A freezing apparatus including a freezing tube unit and a freezing method using the freezing apparatus will be described. However, the underground structure is not limited to a manhole, and any form may be used as long as the structure is partially embedded in the underground.

1. Overall Configuration FIG. 1 is an overall configuration diagram for explaining a situation in which a freezing apparatus according to an embodiment of the present invention is set inside an underground structure and the ground around the underground structure is frozen.

  In order to reinforce or renovate the manhole 3 buried below the ground surface 1, it is effective to flood the ground from the ground 2 existing around the manhole 3 into the manhole 3 and to cause the ground 2 to collapse. There is a need to prevent. In the freezing apparatus according to the embodiment of the present invention, the freezing tube 10 constituting a part of the freezing apparatus is arranged inside the manhole 3 and the outside of the freezing pipe 10 is arranged through the wall surface of the manhole 3 by the refrigerant supplied to the freezing pipe 10. The ground 2 is frozen. The conventional apparatus and the freezing method are greatly different in that the ground 2 is cooled from the inside of the manhole 3. The manhole 3 is usually provided with an existing drain pipe 4 in the vicinity of the bottom thereof. In this embodiment, necessary piping and the like are arranged in the manhole 3 and the drain pipe 4 so that the sewage flowing through the drain pipe 4 can be used even during the freezing period of the ground 2.

  The freezing apparatus 5 used here includes a plurality of freezing tubes 10. In FIG. 1, the freezing tube 10 is drawn in black. The freezing tube 10 is attached to the inside of the manhole 3 at a position near or at the bottom of the manhole 3. However, the freezing tube 10 may be fixed inside the manhole 3 by a method other than attaching the freezing tube 10, for example, a method of jointing the freezing tube 10 to a fixture fixed inside the manhole 3. In this embodiment, the freezing tube 10 has a hollow, substantially rectangular parallelepiped shape of 100 mm × 40 mm × 1000 mm, but is not limited to such dimensions and shapes.

  On the ground surface 1, one or a plurality of liquid nitrogen cylinders 11 in which liquid nitrogen which is an example of a refrigerant is sealed at a high pressure are arranged. The liquid nitrogen cylinder 11 passes through a pressure regulator connected to the cylinder 11, a valve 12, a pipe 13, and a flexible tube 14 branched from the pipe 13 in order, and a part of the plurality of freezing pipes 10. The freezing tube 10 is connected. Further, a flexible tube 15 is connected to a part of the freezing tube 10, and the flexible tube 15 extends to the ground surface 1. In addition to liquid nitrogen, other refrigerants such as liquid air and chlorofluorocarbon may be used.

  As will be described later, the valve 12 is an electromagnetic valve so that it can be opened and closed based on the temperature of liquid nitrogen flowing through the freezing tube 10, but may be another type of valve such as an air valve. In this embodiment, the pipe 13 or the flexible tubes 14 and 15 are made of stainless steel, but the material is not limited to the material. You can also

  A thermocouple 16 as an example of a temperature sensor is inserted on a part of the freezing tube 10 (in this embodiment, the freezing tube 10 through which liquid nitrogen flows) (on the inner surface side of the manhole 3). The thermocouple 16 is electrically connected to a control device 19 disposed on the ground surface 1 via an electric cable 17. Further, the control device 19 is connected to the valve 12 via the electric cable 18. Based on the temperature information of the liquid nitrogen measured by the thermocouple 16, the control device 19 opens the valve 12 in a situation where the supply of liquid nitrogen is necessary, and controls the valve 12 to be closed when the supply is unnecessary. It can be carried out. In this embodiment, the thermocouple 16 is a T thermocouple (a thermocouple using pure Cu for the plus leg and a Cu-Ni alloy (constantin) for the minus leg) that has relatively high accuracy and low electrical resistance. . However, the thermocouple 16 is not limited to a T thermocouple, and for example, a K thermocouple, a J thermocouple, an E thermocouple, a CrAu thermocouple, a CuAu thermocouple, or the like may be employed. Further, the thermocouple 16 may be inserted into all the freezing tubes 10.

  Within the pipe of the drain pipe 4, water stop plugs 21 are arranged on the upstream side and the downstream side, respectively. Each water stop plug 21 is formed with a hole penetrating in the flowing direction of sewage or the like, and a temporary pipe 20 is provided so as to connect the holes. The freezing tube 10 is affixed to the inner surface of the manhole 3 so that the temporary piping 20 is between the freezing tubes 10 or in a region where the freezing tube 10 does not exist. As described above, by disposing the water stop plug 21 and the temporary pipe 20, it is possible to use sewage flowing through the drain pipe 4 even during the freezing period of the ground 2. As the water stop plug 21, a rubber or resin stopper having excellent elasticity is preferable in order to minimize the gap between the drain pipe 4 and the temporary pipe 20, but a material other than rubber or resin may be used. The temporary pipe 20 is preferably made of metal, resin, or the like, but may be made of any material.

2. Configuration of Freezing Device FIG. 2 is a view of a state in which the freezing device according to the embodiment of the present invention is fixed to the inside of the manhole when viewed from the opening side (the ground surface side) of the manhole and a partially enlarged view thereof. is there.

  The freezing device 5 includes 16 freezing tubes 10, a tube 30 for connecting the freezing tubes 10, and fixing fittings 35 a and 35 b for fixing the freezing tube 10 to the inside of the manhole 3. The freezing tube 10 is fixed inside the manhole 3 with its length direction (direction of dimension 1000 mm, reverse direction of the paper) as a vertical direction. In FIG. 2, the freezing tube 10 is illustrated with its upper surface as a hatched area. The freezing tube 10 constitutes a freezing tube unit 22 as a set of four. In this embodiment, the distance between adjacent freeze tubes 10 in the freeze tube unit 22 is set to approximately 150 mm, but is not limited to this distance. The freezing tube unit 22 is formed by connecting four freezing tubes 10 each having an inlet and an outlet for liquid nitrogen, and liquid nitrogen injected from the inlet of one freezing tube 10 is used for the remaining three freezing tubes 10. It passes through the outlet of the last freezing tube 10 and has a structure. Four sets of freezing tube units 22 having such a structure are fixed inside the manhole 3. Each freezing tube 10 needs to be attached as close to the curved inner surface of the manhole 3 as possible so as to facilitate heat exchange with the ground 2 outside the manhole 3. For this reason, the putty 25 as a clogging member is interposed between each freezing tube 10 and the inner surface of the manhole 3 (see the black portion of the enlarged view A in FIG. 2). The putty 25 is preferably made of a material that is sufficiently flexible to fill the gap, has high thermal conductivity, and has low temperature resistance, such as a liquid polymer (polybutene-based). However, the putty 25 is not an essential component for the freezing apparatus 5. For example, when one surface of the freezing tube is a curved surface that matches the curved surface inside the manhole 3, the putty 25 is not used, or Even if it is used, it can be interposed very thinly.

  Each freezing tube unit 22 has a configuration in which four freezing tubes 10 are connected by a tube 30. The tube 30 is made of stainless steel, resin, or other material. At the top of each freezing tube 10, an inlet and an outlet for liquid nitrogen are provided. For example, in the case of the upper left freezing tube unit 22 in FIG. 2, the flexible tube 14 is connected to the inlet above the lower left freezing tube (first freezing tube) 10, and the outlet below the first freezing tube 10. To the inlet above the other freezing pipe (second freezing pipe) 10 above it is connected by a tube 30, and another freezing next to the upper side from the outlet below the second freezing pipe 10. The tube (third freezing tube) 10 is connected to the inlet above the tube 30 by a tube 30, and another freezing tube (fourth freezing tube) 10 adjacent to the upper side from the outlet below the third freezing tube 10 is connected. The tube 30 is connected to the inlet on the right side, and the flexible tube 15 is connected to the outlet on the left side of the fourth freezing tube 10. The above connecting method of the upper left freezing tube unit 22 in FIG. 2 is also adopted in the lower right freezing tube unit 22 in FIG.

  2, the flexible tube 14 is connected to the inlet on the left side of the upper left freezing tube (first freezing tube) 10 and the outlet on the right side of the first freezing tube 10 is used. To the inlet above the other freezing pipe (second freezing pipe) 10 next to the lower freezing pipe 10 is connected by the tube 30, and another freezing adjacent to the lower side from the outlet below the second freezing pipe 10. The tube (third freezing tube) 10 is connected to the inlet located above the tube 30 by a tube 30, and another freezing tube (fourth freezing tube) 10 adjacent to the lower side from the outlet below the third freezing tube 10. A tube 30 is connected to an upper inlet, and a flexible tube 15 is connected to an outlet below the fourth freezing tube 10. The above connecting method of the upper right freezing tube unit 22 in FIG. 2 is also adopted in the lower left freezing tube unit 22 in FIG.

  As described above, the freeze tube unit 22 employs two types of connection methods, but only one type of connection method may be employed. Further, instead of flowing liquid nitrogen to the adjacent freezing tube 10, the first freezing tube 10 to the third freezing tube 10, the third freezing tube 10 to the second freezing tube 10, and the second freezing tube 10 to the fourth freezing tube 10. Liquid nitrogen may be allowed to flow so as to skip to the freezing tube 10. Whatever the order, liquid nitrogen may be connected so as to flow through the four freezing tubes 10. Further, instead of the four freezing tubes 10 constituting one freezing tube unit 22, two, three, or five or more freezing tubes 10 may constitute one freezing tube unit. . Further, the number of the freezing tubes 10 constituting the freezing tube unit may be plural types instead of one. In that case, for example, a freezing tube unit including two freezing tubes 10 and a freezing tube unit including three freezing tubes 10 may be attached to the inner surface of the manhole 3.

  The freezing device 5 includes fixing metal fittings 35 a and 35 b as split-shaped fixing members that form part of a frame for fixing the 16 freezing tubes 10 toward the inner surface of the manhole 3. The fixing brackets 35a and 35b are both substantially half-shaped brackets. The fixing bracket 35 a is for fixing the eight freezing tubes 10 on the left side in FIG. 2 to the inner surface of the manhole 3. The fixing bracket 35 b is for fixing the eight freezing tubes 10 on the right side in FIG. 2 to the inner surface of the manhole 3. The fixing bracket 35a and the fixing bracket 35b are connected to each other in the lengthwise direction by a stopper (for example, a bolt) 37 and a stopper (for example, a bolt) 38. The fixing fittings 35a and 35b are provided with a protrusion 36 that protrudes outward from the region in contact with the freezing tube 10 so that the freezing tubes 10 are in contact with or close to the inner surface of the manhole 3. The putty 25 may be interposed between the protrusion 36 and the inner surface of the manhole 3. As shown in the enlarged view in FIG. 2, the fixing brackets 35 a and 35 b and each freezing tube 10 are fastened and fixed by bolts 39. Screw holes that pass through the freezing pipes 10 are formed in the inner portions of the fixing metal fittings 35a and 35b that are in contact with the freezing pipes 10. By screwing bolts 39 into the screw holes, the fixing metal fittings 35a and 35b Each freezing tube 10 can be strongly joined. Note that the fixing bracket 35a and the fixing bracket 35b do not have to be substantially halved. For example, the shape of the fixture 35a may be a small arc shape with a central angle of about 60 degrees, and the shape of the fixture 35b may be a large arc shape with a center angle of about 300 degrees. Further, a completely frame-shaped fixing member may be used without using the split-shaped fixing brackets 35a and 35b. Further, instead of the manhole 3, for example, in the case of a rectangular underground buried object, a rectangular frame-shaped fixing bracket or a split-shaped fixing member obtained by dividing the rectangular frame-shaped fixing bracket into a plurality of pieces may be used. .

3. Configuration of Freezing Tube FIG. 3 is a cross-sectional view showing the internal structure of the freezing tube.

  The freezing tube 10 includes an inlet 40a serving as an inlet for liquid nitrogen and an outlet 40b serving as an outlet for liquid nitrogen. In this embodiment, the injection port 40a and the discharge port 40b are cylinders that protrude above the connection pipe 10, but may be square tubes. Further, the injection port and the discharge port of the freezing tube 10 may be formed as simple holes without protruding upward, or may be formed so as to protrude inward of the freezing tube 10.

  Inside the freezing tube 10, an inner tube 41 for forming a liquid nitrogen channel is inserted. The inner tube 41 extends from the inner upper portion of the freezing tube 10 to the vicinity of the inner bottom portion, but does not contact the inner bottom portion. As shown by the arrow in FIG. 3, the liquid nitrogen that has entered from the inlet 40a first flows in the inner tube 41 from the upper side to the lower side of the freezing tube 10, returns from the lower side to the upper side of the freezing tube 10, and the discharge port 40b. This is because a flow path is formed so as to exit from.

4). Freezing Device Setting Method FIG. 4 is a diagram illustrating a state in which a fixing metal fitting, which is a partial configuration of the freezing device, is carried into the manhole. FIG. 5 is a diagram illustrating the fixing bracket in a state where the half-shaped fixing bracket is joined.

  Each of the fixing brackets 35a and 35b is a half-shaped bracket, and is fixed in an annular shape as shown in FIG. 5 by joining with screw bolts 37 and 38 so that the screw holes at the ends of each other overlap each other. The metal fitting 35 can be completed. If an annular fixing bracket that cannot be divided from the beginning is used, it is difficult to carry it into the manhole 3. However, if the annular fixing bracket 35 can be divided into two half-shaped fixing brackets 35a and 35b as in this embodiment, the half-shaped fixing brackets 35a and 35b are respectively connected by ropes 45 or the like. The manhole 3 is lowered in the direction of arrow A in FIG. 4, and the fixing brackets 35 a and 35 b can be easily carried into the manhole 3. In addition, the operation of fixing the freezing tube 10 (the black portion in FIG. 4) with the fixing brackets 35a and 35b can be easily performed.

  FIG. 6 is a perspective view showing a state in which each freezing tube is fixed to the inner surface of the manhole with a fixing bracket.

  In this embodiment, the fixing bracket 35 is made of stainless steel or steel and has a U-shaped cross section with a width of about 100 mm. The fixing bracket 35 includes a plurality of protruding portions 36 that protrude outwardly so as to come into contact with or close to the inner surface of the manhole 3 between adjacent freezing tubes 10, and are formed between the protruding portions 36. Each fixing tube 35 is pressed in the direction of arrow A in FIG. 6 so that each freezing tube 10 is in contact with the recess, and is fixed to each freezing tube 10.

  The fixing method is performed using the bolt 39 as described above. As shown in FIG. 6, the screw hole for fixing the freezing tube 10 with the bolt 39 may be formed in the fixing bracket 35 so as to be one for each freezing tube 10. A screw hole may be formed in the fixing bracket 35 so that it can be fixed to the fixing bracket 35 at the positions of the freezing tubes 10 at both ends.

  Further, the fixing bracket 35 may be widened and fixed to one freezing tube 10 with bolts or the like at two or more locations. Alternatively, two or more fixing brackets 35 may be prepared, and each freezing tube 10 may be fixed by the fixing brackets 35 in a plurality of stages in the vertical direction.

  FIG. 7 is a diagram showing a state in which the inside of the manhole is virtually expanded left and right, and the freezing tubes fixed on the inside are arranged in the left-right direction.

  As described above, liquid nitrogen is injected and discharged in units of the freezing tube unit 22. For this reason, taking the two freezing tube units 22 on the left side of FIG. 7 as an example, as shown by the arrows in FIG. 7, the liquid nitrogen injected from the flexible tube 14 into the leftmost freezing tube 10 is It flows through the inside of the freezing tube 10, flows in order to the right freezing tube 10 via the tube 30, and is discharged from the rightmost freezing tube 10 to the flexible tube 15. The same applies to the two freeze tube units 22 on the right side of FIG.

  A thermocouple 16 is arranged on the outer surface of one freezing tube 10 in each freezing tube unit 22, and the temperature of the freezing tube 10 into which liquid nitrogen has been injected can be measured. In addition, the freezing pipe 10 is arranged so as to avoid the position of the temporary piping 20 so that the temporary piping 20 attached to the drain pipe 4 does not overlap the freezing pipe 10. In this embodiment, the freezing pipes 10 are all the same size, but another freezing pipe having a short vertical length is mixed and another short freezing pipe and a freezing pipe are placed at the position of the temporary pipe 20. The pipe 10 may be arranged with a gap in the vertical direction, and the temporary pipe 20 may be arranged in the gap.

5). Freezing method Next, a freezing method according to an embodiment of the present invention will be described.

  The freezing method according to this embodiment has the following steps. After carrying in the liquid nitrogen cylinder 11 in which liquid nitrogen, which is an example of a refrigerant, is filled with high pressure, and each device (carrying-in step), the liquid nitrogen cylinder 11 and the pressure regulator are connected, the valve 12 is connected thereto, the pipe 13, The flexible tubes 14 are connected in sequence (refrigerant channel connection step). Moreover, while connecting the control apparatus 19 and the valve | bulb 12 with the electrical cable 18, the control apparatus 19 and each thermocouple 16 are connected with the electrical cable 17 (control path | route connection step). A plurality of freezing tubes 10 having liquid nitrogen inlets 40a and outlets 40b are connected by a tube 30 and arranged along the inner surface of the manhole 3 (freezing tube arranging step). In addition, the frozen tube 10 is pasted through a putty 25 which is a clogging member, the fixing brackets 35a and 35b are carried into the manhole 3, and the frozen tube 10 is fixed by the fixing brackets 35a and 35b (fixing of the frozen tube). Step). Further, the fixing bracket 35a and the fixing bracket 35b are connected (fixing bracket connecting step). The flexible tube 14 is connected to the injection port 40a of the freezing tube 10 that supplies liquid nitrogen first in the unit of the freezing tube unit 22, and the flexible tube 15 is connected to the discharge port 40b of the freezing tube 10 that supplies liquid nitrogen (freezing). Tube connection step in the tube unit). The water stop plug 21 is attached to the drain pipe 4, and the through holes of the water stop plug 21 are connected by the temporary pipe 20 so as to avoid the freezing pipe 10 (temporary pipe installation step).

  In addition, said temporary piping installation step is not essential and can also be abbreviate | omitted. In addition, the order of the refrigerant flow path connection step, control path connection step, freezing tube arrangement step, temporary piping installation step, and tube connection step in the freezing tube unit can be arbitrarily changed without changing the order thereof. . Further, the freeze tube fixing step and the fixing metal fitting connecting step may be performed in reverse order.

  After completing the setting of all the devices, the valve 12 is opened, liquid nitrogen is supplied from the inlet 40a of one freezing tube 10 of the freezing tube 10 constituting the freezing tube unit 22, and finally the liquid nitrogen is supplied. Liquid nitrogen is discharged from the discharge port 40b of another freezing tube 10 that flows (liquid nitrogen supply step). The liquid nitrogen flowing through the plurality of freezing tubes 10 causes heat exchange with the ground 2 via the outer wall of the freezing tube 10 and the inner surface of the manhole 3, thereby freezing the ground 2 outside the manhole 3 (ground freezing). Step).

6). In this embodiment, based on the temperature information detected by the thermocouple 16 which is an example of a temperature sensor installed on the surface of the freezing tube 10 through which liquid nitrogen flows, the supply path for liquid nitrogen is provided. It has a control system for controlling the opening / closing operation of the valve 12 provided. This control method. The valve 12 is controlled so that the valve 12 is closed when the temperature of the freezing tube 10 through which liquid nitrogen flows is smaller than a predetermined value set in advance, and the valve 12 is opened when the temperature is equal to or higher than the predetermined value. The configuration and control contents necessary for realizing this control method will be described below.

  FIG. 8 shows a control device that constitutes a part of a freezing device, a valve in a supply path of liquid nitrogen, and a method for controlling the opening / closing operation of the valve based on a signal of a thermocouple installed on the surface of a freezing pipe through which liquid nitrogen flows It is a schematic diagram for demonstrating.

  The control device 19 includes an interface (I / F) 51 that is a signal inlet from the thermocouple 16, an input device 52 such as a keyboard, a pointing device, and a touch key, a central processing unit (CPU) 53, and a kind of memory. ROM 54, a type of memory RAM 55, a hard disk drive (HDD) 56, an interface (I / F) 57 serving as a signal supply port to the valve 12, and a display 58. However, at least one of the input device 52, the HDD 56, and the display 58 may not be provided.

  The CPU 53 is a part that performs various arithmetic processes and also performs various controls. The ROM 54 includes a mask ROM and a programmable ROM (PROM). The RAM 55 includes a DRAM mainly used as a graphics memory and an SRAM mainly used as a cache memory, in addition to a main memory for storing a control program of the CPU 53 and the like. The HDD 56 is a part that stores an operation system (OS) and application software. A valve control program for controlling the valve 12 to close when the temperature measured by the thermocouple 16 is lower than a predetermined value set in advance and to open the valve 12 when the temperature is equal to or higher than a predetermined value is RAM 55 or It is stored in the HDD 56.

  When the valve 12 is a normally open (always open when no signal is received) type valve, the CPU 53 detects the temperature measured by the thermocouple 16 and pre-determines based on the valve control program. Compare with the set value. As a result, when the temperature is lower than the predetermined value, the CPU 53 sends a signal to the valve 12 via the I / F 57 and closes the valve 12. On the other hand, when the temperature is equal to or higher than the predetermined value, the CPU 53 does not send a signal to the valve 12, so that the valve 12 remains open.

  Further, when the valve 12 is a normally closed type valve (which is always closed when no signal is received), the CPU 53 detects the temperature measured by the thermocouple 16 via the electric cable 17. Then, it is compared with a predetermined value set in advance based on the valve control program. As a result, if the temperature is lower than the predetermined value, the CPU 53 does not send a signal to the valve 12, so that the valve 12 remains closed. On the other hand, when the temperature is equal to or higher than the predetermined value, the CPU 53 sends a signal to the valve 12 via the I / F 57 to open the valve 12.

  As a control method for controlling the opening / closing operation of the valve 12, a signal may be sent to the valve 12 when the temperature is lower than a predetermined value or higher than a predetermined value. When the temperature is lower than the predetermined value, it means that heat exchange with the ground 2 is not performed so much. In such a case, the ground 2 is sufficiently frozen, and the necessity for supplying a large amount of liquid nitrogen is low. Therefore, the valve 12 is closed in order to prevent unnecessary supply of liquid nitrogen. On the other hand, when the temperature is equal to or higher than a predetermined value, it means that heat exchange with the ground 2 is actively performed. In such a case, the ground 2 is in the process of freezing, and it is highly necessary to supply liquid nitrogen continuously. Therefore, the valve 12 is opened to continue the supply of liquid nitrogen.

  The predetermined temperature is preferably compared with an average value of the temperatures measured in the four freeze tube units 22. However, the temperature measured in any one of the freezing tube units 22 is compared with a predetermined temperature, and the valve 12 can be closed when at least one temperature becomes lower than the predetermined temperature. Alternatively, the valve 12 can be closed when two or three temperatures become lower than a predetermined temperature. Furthermore, the valve 12 can be closed when all the temperatures measured in the four freeze tube units 22 become lower than a predetermined temperature.

  Moreover, although the said control system is control of opening and closing of the valve | bulb 12, you may prevent the valve 12 from closing completely by adjusting the open state of the valve | bulb 12. FIG. In addition, thermocouples are arranged at locations near the liquid nitrogen injection side and at the discharge side in one or two or more freezing tubes 10, and control by the control device 19 is performed at the temperature measured by each thermocouple. The valve 12 may be closed when the difference is smaller than a predetermined temperature difference, and the valve 12 may be opened when the difference is greater than the temperature difference.

7). FIG. 9 is an overall configuration diagram (9A) showing a modification of the freezing apparatus according to the present invention and a simplified diagram (9B) showing a state when a part thereof is viewed from the direction of arrow A.

  The freezing device 5 shown in FIG. 9 is different from the freezing device 5 shown in FIG. 1 in that an embedded freezing pipe 60 is inserted into the ground 2 from the side wall surface of the manhole 3. The buried type freezing tube 60 is drawn in black in FIG. The freezing tube unit 22 includes a plurality of buried freezing tubes 60 that can be inserted into the ground 2 outside from the inner surface of the manhole 3 and can supply liquid nitrogen. In this modified example, specifically, as shown in FIG. 9 (9B), a total of ten buried freezing pipes 60 are inserted around the drain pipes 4 on both sides. A tube 61 is connected between the freezing tube 10 and the buried type freezing tube 60 or between the buried type freezing tubes 60.

  The tube 61 may be connected in any way as long as the liquid nitrogen is connected so as to be supplied from the freezing tube 10 to all the buried freezing tubes 60. Further, the buried type freezing tube 60 may have the same form as the freezing tube 10. Further, the buried type freezing tube 60 may be a square tube instead of a cylinder. Further, when screwing, a screw structure may be held on the outer surface of the buried type freezing pipe 60. Further, the buried type freezing pipe 60 is a freezing pipe inserted at an angle of less than 90 degrees from the side wall of the manhole 3 to the ground 2 outside the manhole 3 and upward or downward from the side wall. May be. Further, the number of buried type freezing tubes 60 is not limited to the number shown in FIG. 9 (9B), and may be 1 to 4 or 6 or more. Further, the buried type freezing tube 60 may be disposed above or in the middle of the freezing tube 10 instead of below the freezing tube 10.

8). Action The freezing tube unit 22 is formed by connecting four freezing tubes 10 each having an inlet 40a and an outlet 40b for liquid nitrogen, and liquid nitrogen injected from the inlet 40a of one freezing tube 10 is the remaining freezing tube. 10 through the discharge port 40b of the last freezing tube 10. For this reason, by arranging such a freezing pipe unit 22 inside the manhole 3, the ground 2 outside the manhole 3 can be easily frozen.

  In addition, the freezing tube unit 22 includes an inner tube 41 inside each freezing tube 10, and a liquid nitrogen channel is formed by the inner tube 41 inside each freezing tube 10. It is easy to go inside the freezing tube 10, the effective area for heat exchange with the ground 2 can be widened, and frozen soil is easily formed.

  The freezing tube unit 22 is formed by arranging the freezing tubes 10 along the inner side surface of the manhole 3, and a split-piece-like fixing bracket 35a forming a part of a frame for fixing the freezing tube 10 to the inner side surface thereof. , 35b. For this reason, it is easy to install the freezing tube 10 on the inner surface of the manhole 3 in a narrow space called the manhole 3. In addition, by fixing the freezing tube 10 to the inner surface of the manhole 3 with the fixing brackets 35a and 35b, heat exchange between the ground 2 and the freezing tube 10 can be performed effectively.

  Moreover, since the freezing tube unit 22 is further provided with the embedded freezing tube 60 that can be inserted into the ground 2 outside the manhole 3 from the inner side surface and can supply liquid nitrogen, the embedded freezing tube 60 is inserted. The area and the surrounding ground 2 can be frozen more rapidly.

  The freezing device 5 includes a freezing tube unit 22 and is detected by a thermocouple 16 disposed on the surface of the freezing tube 10 through which liquid nitrogen flows, a valve 12 provided in a supply path of liquid nitrogen, and the thermocouple 16. And a control device 19 for controlling the opening / closing operation of the valve 12 based on the temperature information, and the control device 19 has a predetermined temperature so as to close the valve 12 when the temperature is lower than a predetermined value. The operation of the valve 12 is controlled so that the valve 12 is opened when the value is greater than or equal to the value. For this reason, the supply of liquid nitrogen can be automatically controlled, and frozen soil can be formed with the supply of as little liquid nitrogen as possible.

  In the freezing method according to the present embodiment, a plurality of freezing tubes 10 are connected, arranged along the inner surface of the manhole 3, and liquid nitrogen is supplied from the inlet 40a of one freezing tube 10, Liquid nitrogen is discharged from the discharge port 40 b of another freezing tube 10, and heat exchange is performed with the ground 2 through the outer wall of each freezing tube 10 and the inner surface of the manhole 3 by liquid nitrogen flowing through the plurality of freezing tubes 10. And the ground 2 outside the manhole 3 is frozen. By using such a freezing method, frozen soil can be formed without damaging the manhole 3, the drain pipe 4 and the surrounding ground 2 and any reinforcement / repair work in the manhole 3 can be performed. In addition, the construction can be realized safely and at low cost.

  Further, in this freezing method, in the step of arranging the plurality of freezing tubes 10 along the inner side surface of the manhole 3, the putty 25 is interposed in the gap between the freezing tube 10 and the inner side surface. Without this, the heat exchange rate with the surrounding ground 2 can be further improved from the freezing tube 10 through the side wall of the manhole 3. In particular, the putty 25 can be used repeatedly by using a material that does not fluidize.

  Further, in this freezing method, the water stop plugs 21 are respectively arranged on the upstream side and the downstream side of the drain pipe 4, the temporary pipes 20 penetrating the two water stop plugs 21 are installed, and the freeze pipe 10 is connected to the temporary pipe 20. Arrange to avoid. For this reason, sewage can be used even during the reinforcement / renovation work of the manhole 3.

  The present invention creates a frozen soil on the ground below the groundwater level around an existing small-scale underground structure such as a manhole, and the ground collapse associated with water leakage when partially drilling or opening the existing small-scale underground structure. Can be used to prevent.

2 Ground 3 Manhole (an example of an underground structure)
4 Drain pipe 5 Freezing device 10 Freezing pipe 12 Valve 16 Thermocouple (example of temperature sensor)
19 Control device 20 Temporary piping 21 Water stop plug 22 Freezing tube unit 25 Putty (an example of a clogging member)
35 Fixing bracket (fixing member)
35a Fixing bracket (split-shaped fixing member)
35b Fixing bracket (split fixing member)
40a Inlet 40b Discharge port 41 Inner tube 60 Buried cryo tube

Claims (8)

  A plurality of cryotubes having refrigerant inlets and outlets are connected, and the refrigerant injected from the inlet of one cryotube passes through the plurality of cryotubes and from the outlet of another cryotube. A cryopipe unit having a structure to be discharged.   Two or more freezing pipes are arranged along the inner surface of an underground structure, and a frame shape for fixing the two or more freezing tubes on the inner surface or a piece-like fixing that forms a part of the frame body The cryopipe unit according to claim 1, further comprising a member.   The cryopipe unit according to claim 1 or 2, further comprising one or a plurality of buried type cryopipes that are inserted from the inner side surface of the underground structure into the ground outside thereof and capable of supplying a refrigerant. . A plurality of cryotubes having refrigerant inlets and outlets are connected, and refrigerant injected from the inlet of one cryotube passes through one or more of the cryotubes and the exhaust of another cryotube. Including a cryopipe unit having a structure discharged from the outlet;
A temperature sensor arranged on the surface of the freezing pipe through which the refrigerant flows;
A valve provided in a refrigerant supply path;
A control device for controlling the opening and closing operation of the valve based on the temperature information detected by the temperature sensor,
The control device controls the operation of the valve so as to close the valve when the temperature is lower than a predetermined value set in advance and open the valve when the temperature is equal to or higher than the predetermined value. Freezing device to do. A plurality of cryotubes having refrigerant inlets and outlets are connected, arranged along the inner surface of the underground structure,
Supplying the refrigerant from the inlet of one of the freezing tubes, discharging the refrigerant from the outlet of the other freezing tube,
The refrigerant flowing through the plurality of freezing pipes causes heat exchange between the outer wall of the freezing pipe and the ground outside of the underground structure through the inner surface of the underground structure, and the ground outside the underground structure is A freezing method characterized by freezing.   6. The step of arranging the plurality of freezing pipes along the inner side surface of the underground structure includes a clogging member interposed in a gap between the freezing pipe and the inner side surface. Freezing method. In the case of having a drain pipe that passes through the underground structure,
Disposing water stop plugs on the upstream side and downstream side of the drain pipe,
Install temporary piping that penetrates the two water stop plugs,
The freezing method according to claim 5 or 6, wherein the freezing pipe is disposed so as to avoid the temporary piping. Based on the temperature information detected by the temperature sensor arranged on the surface of the freezing pipe through which the refrigerant flows, the control system for controlling the opening and closing operation of the valve provided in the refrigerant supply path,
6. The operation of the valve is controlled so that the valve is closed when the temperature is lower than a predetermined value, and the valve is opened when the temperature is equal to or higher than the predetermined value. The freezing method according to claim 7.

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