JP2019060076A - Ground improvement method and covering material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground improvement method and a covering material which can be constructed in a short period of time and can easily restore the current state after work. SOLUTION: A refrigerant circulation pipe 7 is installed in a horizontal direction on a surface 15 of a ground 1 which is a soft ground. The refrigerant circulation pipes 7 are installed at predetermined intervals in the pipe axis direction, and are connected in series by the connecting pipe 13. Next, the frozen refrigerant is circulated horizontally in the refrigerant circulation path 17 of the refrigerant circulation pipe 7 to start freezing, and after a predetermined time has elapsed, the freezing range 21 is formed on the surface layer portion 19 of the ground 1. Make sure you are there. After that, the upper surface 8 of the refrigerant circulation pipe 7 and the surface 15 of the ground 1 are covered with the covering material 23, the crane 25 is installed to measure the subsidence, and if the subsidence amount clears the standard value, the improved ground is put into service. Start. When the work is completed, the service is terminated, the freezing range 21 is thawed, the covering material 23 and the refrigerant circulation pipe 7 are removed, and the surface layer portion 19 of the ground 1 is returned to the original state. [Selection diagram] Fig. 2

Description

  The present invention relates to a ground improvement method and a covering material.

  When heavy structures such as heavy machinery are used on soft clay soil, if soil or crushed stone is spread directly on the ground, the soft soil may not be able to support the weight of the soil, crushed stone, heavy machinery, etc. Therefore, conventionally, a solidifying material such as cement is added to soft soil and mixed, and the surface layer portion of the ground is reinforced by cement-modified soil.

  As another method of strengthening the surface layer of the ground, the bag body is laid in a grid shape on a planar member laid on the ground, and the bag body is filled with the flowable solidifying material and solidified, and the rigidity on the ground There has been a method of forming a reinforcing body (see, for example, Patent Document 1). There is also a method of forming a frozen soil layer by driving a frozen pipe in a vertical direction to a predetermined depth to form a frozen soil layer and laying a backing plate on the upper surface of the frozen soil layer (see, for example, Patent Document 2).

JP 2012-31596 A Japanese Examined Patent 7-882

  However, if the surface layer of the ground is reinforced using cement-modified soil in areas such as riverbeds and leased lands, removal of the reinforced part is not easy, and restoration of the current state of the ground is difficult. In addition, the removed cement-modified soil had to be treated as industrial waste. On the other hand, the method of forming a rigid reinforcement and the method of forming a frozen soil layer by driving a frozen pipe in the vertical direction are relatively easy to restore the present condition after work, so they are suitable for application to riverbeds and leased land However, it took days for construction.

  The present invention has been made in view of the above-mentioned problems, and its object is to provide a ground improvement method and a covering material which can be constructed in a short period of time and which can easily be restored after the operation. It is.

  In the first invention for achieving the above-mentioned object, in the step a of installing the refrigerant circulation pipe in the horizontal direction near the surface of the ground, and circulating the frozen refrigerant in the refrigerant circulation pipe, the surface layer of the ground It is a ground improvement construction method characterized by including the process b of freezing the frozen range of a part.

  By installing the refrigerant circulation pipe in the horizontal direction near the surface of the ground and circulating the frozen refrigerant in the horizontal direction, it is possible to form a freezing range for strengthening the surface layer portion of the ground in a short time. In addition, the present condition can be easily restored after work by the melting of the freezing range and the removal of the refrigerant circulation pipe.

In the first aspect of the invention, it is preferable that a covering material that covers the upper surface of the refrigerant circulation pipe and the surface of the ground be disposed.
If a steel member such as a base plate is provided as a covering material on the upper surface of the refrigerant circulation pipe or on the surface of the ground, the heat conduction effect of the covering material efficiently cools the cold refrigerant in the refrigerant circulation pipe. Can be transmitted to Further, if crushed stone or earth and sand is provided as the covering material, the heat insulation effect of the covering material makes it difficult for cold heat to escape from the frozen refrigerant or the ground.

The covering material is plate-like or block-like, and a recess or a hole is provided at a predetermined location of the covering material, and the refrigerant circulation pipe is detachably disposed in the recess or the hole. The covering material and the refrigerant circulation pipe may be integrated.
Thereby, it can install in the surface vicinity of the ground in the state which unified a covering material and piping for refrigerant circulation.

At least a part of the covering material may be earth and sand containing water, and the earth and sand may be frozen by circulating the frozen refrigerant through the refrigerant circulation pipe.
If the soil containing water is frozen so that the upper side becomes convex by cold heat from the lower side, the supporting effect of the covering material against the load from the upper side can be enhanced by the arch effect.

It is desirable that the refrigerant circulation pipe be an aluminum extrusion molded article provided with a refrigerant circulation passage.
By using an aluminum extrusion, it is possible to obtain a light-weight and refrigerant conduction pipe excellent in thermal conductivity.

In the step a, for example, the plurality of refrigerant circulation pipes are arranged in a direction perpendicular to the pipe axis direction at predetermined intervals and connected in series.
The circulation direction of the freezing can be specified by circulating the freezing refrigerant in order in the plurality of refrigerant circulation pipes connected in series.

Alternatively, in the step a, the plurality of refrigerant circulation pipes may be disposed in parallel at predetermined intervals in a direction orthogonal to the pipe axis direction and connected in parallel.
By simultaneously circulating the frozen refrigerant through a plurality of refrigerant circulation pipes connected in parallel, the entire freezing range can be uniformly frozen in a short time.

Alternatively, in the step a, the plurality of refrigerant circulation pipes may be disposed at predetermined intervals in the pipe axial direction and the direction orthogonal to the pipe axis.
By appropriately setting the installation interval of the refrigerant circulation pipe in the pipe axial direction and the direction orthogonal to the pipe axis, it is possible to freeze the freezing range by effectively utilizing cold heat.

A heat insulating layer may be formed on the upper side surface of the refrigerant circulation pipe.
If a heat insulating layer having lower thermal conductivity than the lower surface which is a surface facing the ground is formed on the upper surface of the refrigerant circulation pipe, the cold heat of the frozen refrigerant is unlikely to escape upward.

After the step b, a step c may be further included, wherein heat is circulated through the refrigerant circulation pipe to promote the melting of the freezing range.
As a result, the freezing range can be melted in a short time, and the time required to restore the current state can be further shortened.

In the step b, a frozen part higher in strength than the center may be formed in a part out of the center of the freezing range.
Thereby, when using heavy machines, such as a crane, on a freezing range, the intensity | strength of the part to which the load by heavy machines is applied can be made high.

  A second aspect of the invention is a plate-like or block-like covering material for covering the surface layer portion of the ground, wherein a recess or a hole is provided at a predetermined location, and the refrigerant is disposed in the horizontal direction near the surface of the ground. The covering material is characterized in that the circulation pipe is detachably disposed in the recess or the hole portion, thereby being integrated with the refrigerant circulation pipe.

  By using the coating material of the second invention, the integrated coating material and the refrigerant circulation pipe can be simultaneously installed or removed near the surface of the ground. In addition, if the refrigerant circulation pipe can be desorbed from the coating material, it can be removed and diverted.

  According to the present invention, it is possible to provide a ground improvement method and a covering material which can be constructed in a short period of time and which can easily be restored after the operation.

Figure showing the flow chart of the ground improvement method Diagram showing the installation method etc. of the refrigerant circulation pipe 7 A diagram showing an example in which a plurality of refrigerant circulation pipes 7 are connected in parallel Diagram showing another arrangement example of refrigerant circulation piping Figure showing the flow chart of the ground improvement method Diagram showing the installation method etc. of the refrigerant circulation pipe 7 The figure which shows the example using the covering material 41 which has the hole 43 Figure showing an example using crushed stone and soil as covering material 27 The figure which shows the example which formed the frozen part whose strength is stronger than the center in the part which deviated from the center The figure which shows the example of the section of ground 1 which installed piping for refrigerant circulation

Hereinafter, a first embodiment of the present invention will be described in detail based on the drawings.
FIG. 1 is a diagram showing a flowchart of the ground improvement method. FIG. 2 is a view showing a method of installing the refrigerant circulation pipe 7 and the like. 2 (a) and 2 (b) are diagrams showing the arrangement of the refrigerant circulation pipe 7, and FIG. 2 (b) is a cross-sectional view taken along arrow CC shown in FIG. 2 (a). 2 (c) is a perspective view of the refrigerant circulation pipe 7, FIG. 2 (d) is a view showing a state in which the ground 1 is frozen, and FIG. 2 (e) is a diagram showing the frozen ground 1 in service. It is a figure which shows the state which is.

  In the first embodiment, the surface layer of the ground is improved as a measure for supporting the scaffold of the crane on a soft ground. Below, the ground improvement method of 1st Embodiment is demonstrated along the flowchart shown in FIG.

  In the ground improvement method of the first embodiment, first, the installation conditions of the refrigerant circulation pipe 7 are examined (S101). Then, the refrigerant circulation pipe 7 is installed on the surface 15 of the ground 1 (S102). In S102, as shown in FIGS. 2 (a) and 2 (b), the refrigerant circulation pipe 7 is horizontally installed on the surface 15 of the planned freezing area 3 of the ground 1 which is a soft ground. The refrigerant circulation pipes 7 are arranged at predetermined intervals in the axial direction of the pipe, for example, at intervals of 1 m. The planned freezing range 3 is a range in which it is necessary to increase the strength of the ground 1 in order to install the crane 25 shown in FIG. 2 (e). The planned freezing area 3 is set, for example, with a margin of 1 m around the crane installation point 5.

  The refrigerant circulation pipe 7 is connected in series by the connection pipe 13. The supply pipe 9 is connected to one end of the plurality of refrigerant circulation pipes 7 connected in series, and the return pipe 11 is connected to the other end. The supply pipe 9 and the return pipe 11 are connected to a refrigerant circulator (not shown).

  After S102, the frozen refrigerant is circulated through the refrigerant circulation pipe 7 to start freezing (S103). As shown to Fig.2 (a), a freezing refrigerant | coolant flows in into the piping 7 for refrigerant | coolant circulations via the supply piping 9 as shown to arrow A1 from the refrigerant | coolant circulator which is not shown in figure. Then, it passes through the plurality of refrigerant circulation pipes 7 and the connection pipe 13 connected in series, and returns to the refrigerant circulator (not shown) through the return pipe 11 as indicated by the arrow B1.

  As shown in FIG. 2 (c), the refrigerant circulation pipe 7 is a plate-like member and is an aluminum extrusion. The refrigerant circulation pipe 7 internally includes a plurality of refrigerant circulation paths 17 which are flow paths of the frozen refrigerant. The frozen refrigerant circulates in the horizontal direction in the refrigerant circulation path 17 of the refrigerant circulation pipe 7 installed in the horizontal direction on the surface 15 of the ground 1.

  After a predetermined time has elapsed since the circulation of the freezing refrigerant was started in S103, freezing is confirmed (S104). In S104, as shown in FIG. 2 (d), it is confirmed that the freezing range 21 is formed in the surface layer 19 of the ground 1. It is desirable to determine the freezing completion time by grasping the freezing completion time by the existing design method. For confirmation of freezing, for example, a thermometer is installed between the refrigerant circulation pipes 7 arranged at predetermined intervals to measure the temperature, the freezing depth is measured with a freezing depth meter using methylene blue, a supply piping The temperature difference between the frozen refrigerant at the inlet of the fuel cell 9 and the outlet of the return pipe 11 is measured, the elastic modulus is measured by falling ball survey, and the strength is measured by cone penetration.

  After freezing is confirmed in S104, the covering material 23 is laid (S105), and the crane 25 is installed to perform settlement measurement (S106). In S105, as shown in FIG. 2E, the upper surface 8 of the refrigerant circulation pipe 7 and the surface 15 of the ground 1 are covered with a covering material 23. The covering material 23 is, for example, a floor plate. In S106, as shown in FIG. 2 (e), the crane 25 is installed on the covering material 23 laid in S105, and the amount of settlement of the freezing range 21 is measured.

  If the amount of settlement measured in S106 does not clear the reference value, the crane 25 is retracted, the circulation of the frozen refrigerant is continued without starting the service, and S106 is performed again. If the amount of settlement measured in S106 clears the reference value, as shown in FIG. 2 (e), the crane 25 is installed on the freezing range 21 and service is started (S107).

  When the work is completed, the crane 25 is retracted to end the service (S108), and the freezing range 21 is thawed (S109). In S109, the circulation of the freezing refrigerant is stopped to melt the freezing range 21, the covering material 23 and the refrigerant circulation pipe 7 are removed, and the surface layer 19 of the ground 1 is returned to the original state.

  Thus, in the first embodiment, the refrigerant circulation pipe 7 is installed horizontally in the vicinity of the surface 15 of the ground 1 to circulate the frozen refrigerant in the horizontal direction, thereby strengthening the surface portion 19 of the ground 1 The freezing range 21 to be formed can be formed in a short time, the trafficability of the ground 1 can be improved, and the ground resistance for preventing overturning of heavy machinery etc. can be secured. In addition, the melting of the freezing range 21 and the removal of the refrigerant circulation pipe 7 and the covering material 23 make it possible to easily restore the ground 1 after the operation.

  In the first embodiment, since a lightweight aluminum extrusion is used, transportation of the refrigerant circulation pipe 7 to the site and installation on the ground 1 are easy. Further, since the refrigerant circulation pipe 7 of the aluminum extrusion is excellent in thermal conductivity, the cold heat of the frozen refrigerant can be efficiently transmitted to the surface portion 19 of the ground 1 during the service.

  In the first embodiment, as shown in FIG. 2A, a plurality of refrigerant circulation pipes 7 are connected in series. If the frozen refrigerant is sequentially circulated through the plurality of refrigerant circulation pipes 7 connected in series, it is possible to specify the advancing direction of freezing in the freezing range 21. Therefore, connection in series is useful, for example, when freezing the soft ground of a riverbank from the side far from the riverbank.

  In the first embodiment, the plurality of refrigerant circulation pipes 7 are disposed at predetermined intervals in the direction orthogonal to the pipe axis direction and connected in series, but the arrangement and connection of the refrigerant circulation pipes are described. The method is not limited to that shown in the first embodiment. In the example shown below, points different from the first embodiment will be described, and the same points will be denoted by the same reference numerals in the drawings and the like, and the description will be omitted.

  FIG. 3 is a view showing an example in which a plurality of refrigerant circulation pipes 7 are connected in parallel. In the example shown in FIG. 3, one ends of the plurality of refrigerant circulation pipes 7 arranged at predetermined intervals in the direction orthogonal to the pipe axis direction are respectively connected to the branch pipes 31 a branched from the supply pipe 31. The other end is connected to the branch pipe 33 a branched from the return pipe 33. Thus, the plurality of refrigerant circulation pipes 7 are connected in parallel. The supply pipe 31 and the return pipe 33 are connected to a refrigerant circulator (not shown).

  When a plurality of refrigerant circulation pipes 7 are connected in parallel as shown in FIG. 3, the frozen refrigerant is supplied from the refrigerant circulator (not shown) through the supply pipe 31 and the branch pipe 31a as shown by arrow A2 in S103. It flows into the circulation pipe 7. Then, as shown by the arrow B2, the refrigerant circulation machine returns to the refrigerant circulator (not shown) via the branch pipe 33a and the return pipe 33.

  If the frozen refrigerant is simultaneously circulated through the plurality of refrigerant circulation pipes 7 connected in parallel as shown in FIG. 3, the entire freezing range can be uniformly frozen in a short time. Further, if a jig integrated with the branch pipe 31a and the branch pipe 33a is prepared, even when a large number of refrigerant circulation pipes 7 are installed in a wide range, the plurality of refrigerant circulation pipes 7 can be supplied as supply pipes 31. It becomes possible to connect simultaneously to the return pipe 33 and installation is easy.

  FIG. 4 is a view showing another arrangement example of the refrigerant circulation pipe. In the example shown in FIG. 4 (a), the refrigerant circulation pipe 7a obtained by cutting the refrigerant circulation pipe 7 shown in FIG. 2 (c) to a length of about 1 m is predetermined in the pipe axis direction and the direction orthogonal to the pipe axis. Arrange at intervals. Then, all the refrigerant circulation pipes 7a are connected in series using the connection pipe 13 and the connection pipe 13a. In S103, the frozen refrigerant flows from the supply pipe 9 into the refrigerant circulation pipe 7a as shown by arrow A3, passes through the plurality of refrigerant circulation pipes 7a connected in series, the connection pipe 13, and the connection pipe 13a, and the arrow It returns to the return piping 11 as shown to B3.

  In the example shown in FIG. 4 (b), in addition to the refrigerant circulation pipe 7 shown in FIG. 2 (a), the plurality of refrigerant circulation pipes 7b have predetermined intervals in the pipe axis direction of the refrigerant circulation pipe 7. Place. The plurality of refrigerant circulation pipes 7b are connected in series by the connection pipe 13b. The supply pipe 9b is connected to one end of the plurality of refrigerant circulation pipes 7b connected in series, and the return pipe 11b is connected to the other end.

  In S103, the frozen refrigerant flows from the supply pipe 9 as shown by arrow A4, passes through the plurality of refrigerant circulation pipes 7 and connecting pipes 13 connected in series, and returns to the return pipe 11 as shown by arrow B4. . At the same time, as shown by arrow A5, it flows from the supply pipe 9b, passes through the plurality of refrigerant circulation pipes 7b and connecting pipes 13b connected in series, and returns to the return pipe 11b as shown by arrow B5.

  As shown in each drawing of FIG. 4, if the installation interval of the refrigerant circulation pipe in the direction of the pipe axis and the direction orthogonal to the pipe axis is appropriately set according to the range to be frozen, cold heat is effectively utilized. The freezing range can be frozen.

  In the example shown in FIG. 4 (a), cold heat is transmitted from the portion where the refrigerant circulation pipe 7a is installed to the ground 1, and not transmitted from the portion where the connecting pipe 13a is installed. It is possible to partially freeze and freeze the freezing range efficiently with a small amount of heat. Even when using a long refrigerant circulation pipe 7 as shown in FIG. 2 (a) and FIG. 3, a heat insulating material is wound around the entire circumference of the refrigerant circulation pipe 7 at a predetermined interval in the pipe axis direction. The effect similar to the example shown to Fig.4 (a) is acquired by making it not transmit cold heat to the ground 1 from the part which wound the heat insulating material.

  In the ground improvement method according to the first embodiment, crushed stone, earth and sand, etc. may be used as the covering material 23 without using a floor plate.

  Next, a second embodiment will be described. In the second embodiment, points different from the first embodiment will be described, and the same points will be denoted by the same reference numerals in the drawings and the like, and the description will be omitted.

  FIG. 5 is a view showing a flowchart of the ground improvement method. FIG. 6 is a view showing a method of installing the refrigerant circulation pipe 7 and the like. 6 (a) is a perspective view of the covering material 35, FIG. 6 (b) is a perspective view of the covering material 35 integrated with the refrigerant circulating pipe 7, FIG. 6 (c) is a refrigerant circulating pipe 7 and the covering material. FIG. 6 (d) is a view showing the arrangement of 35, and FIG. 6 (d) is a view showing a state in which the ground 1 is frozen.

  Below, the ground improvement method of 2nd Embodiment is demonstrated along the flowchart shown in FIG. In the ground improvement method of the second embodiment, first, the installation conditions of the refrigerant circulation pipe 7 are examined (S101). Then, the covering material 35 and the refrigerant circulation pipe 7 are installed on the surface 15 of the ground 1 (S112).

  As shown in FIG. 6A, the covering material 35 is a plate-like member made of steel, and groove-like concave portions 37 are provided on one surface at predetermined intervals. As shown in FIG. 2 (b), the refrigerant circulation pipe 7 is installed in the recess 37 of the covering material 35. The refrigerant circulation pipe 7 is removable from the recess 37 of the covering material 35.

  In S112, as shown in FIG. 2 (b), the covering material 35 integrated with the refrigerant circulation pipe 7 is installed on the surface 15 of the ground 1, which is a soft ground, as shown in FIG. 2 (c). The covering material 35 is installed upside down from the state shown in FIGS. 6 (a) and 6 (b) so that the surface on the side where the recess 37 is formed is in contact with the ground 1; And the surface 15 of the ground 1 are covered.

  The refrigerant circulation pipes 7 may be connected in series by a connection pipe as shown in FIG. 2A, or may be connected in parallel by branch pipes as shown in FIG.

  After S112, the frozen refrigerant is circulated through the refrigerant circulation pipe 7 to start freezing (S103). The frozen refrigerant circulates in the horizontal direction in the refrigerant circulation path 17 (FIG. 2C) of the refrigerant circulation pipe 7 installed horizontally on the surface 15 of the ground 1.

  After a predetermined time has elapsed since the circulation of the freezing refrigerant was started in S103, freezing is confirmed (S104). In S104, as shown in FIG. 6 (d), it is confirmed that the freezing range 21 is formed in the surface layer 19 of the ground 1. The timing for confirming freezing and the confirmation method are the same as those in S104 of the first embodiment.

  If it is not confirmed in S104 that the freezing range 21 is frozen, circulation of the freezing refrigerant is continued without starting the service, and S104 is performed again. If it is confirmed that the freezing range 21 is frozen, the service is started (S107). When the work is completed, the service is ended (S108), and the freezing range 21 is thawed (S109). In S109, the circulation of the freezing refrigerant is stopped to melt the freezing range 21, the refrigerant circulation pipe 7 and the covering material 35 are removed, and the surface portion 19 of the ground 1 is returned to the original state.

  Thus, in the second embodiment, the refrigerant circulation pipe 7 is installed horizontally in the vicinity of the surface 15 of the ground 1 to circulate the frozen refrigerant in the horizontal direction, thereby strengthening the surface portion 19 of the ground 1 The freezing range 21 to be formed can be formed in a short time, the trafficability of the ground 1 can be improved, and the ground resistance for preventing overturning of heavy machinery etc. can be secured. In addition, by melting the freezing range 21 and removing the refrigerant circulation pipe 7 and the covering material 35, it is possible to easily restore the ground 1 after the operation.

  In the second embodiment, the covering material 35 and the refrigerant circulation pipe 7 can be simultaneously installed and removed near the surface 15 of the ground 1 by integrating the covering material 35 and the refrigerant circulation pipe 7. Further, if the refrigerant circulation pipe 7 can be desorbed to the covering material 35, it is possible to remove the refrigerant circulation pipe 7 after use and divert it. Furthermore, by disposing the refrigerant circulation pipe 7 in the concave portion 37 of the coating 35 made of steel, cooling heat can be efficiently transferred from the refrigerant circulation pipe 7 to the ground 1 via the coating 35 due to the heat conduction effect of the coating 35 I can tell.

  In the second embodiment, the refrigerant circulation pipe 7 is disposed in the recess 37 provided in the plate-like covering material 35. However, the refrigerant circulation pipe 7 may be disposed in the hole. FIG. 7 is a view showing an example in which the covering material 41 having the hole 43 is used. FIG. 7A is a perspective view of the covering material 41 integrated with the refrigerant circulation pipe 7, and FIG. 7B is a view showing a state in which the ground 1 is frozen.

  As shown in FIG. 7A, the covering material 41 is a plate-like member made of steel, and a hole 43 is provided substantially at the center in the thickness 49 direction at a predetermined interval. The refrigerant circulation pipe 7 is installed in the hole 43 of the covering material 41. That is, the covering material 41 covers the entire surface of the outer periphery of the refrigerant circulation pipe 7. The refrigerant circulation pipe 7 is detachable from the hole 43 of the covering material 41.

  In S112, as shown in FIG. 7B, the covering material 41 integrated with the refrigerant circulation pipe 7 is installed on the surface 15 of the ground 1 which is a soft ground. In S112, the refrigerant circulation pipe 7 is installed near the surface 15 of the ground 1, and the covering material 41 covers the surface 15 of the ground 1. The refrigerant circulation pipes 7 may be connected in series by a connection pipe as shown in FIG. 2A, or may be connected in parallel by branch pipes as shown in FIG.

  Even when the refrigerant circulation pipe 7 and the covering material 41 are integrated using the covering material 41 shown in FIG. 7, the freezing range 21 for strengthening the surface layer portion 19 of the ground 1 can be formed in a short time. The same effects as those of the second embodiment, such as the second embodiment, can be obtained.

  In the second embodiment and the example shown in FIG. 7, the covering member 35 and the covering member 41 which are steel plate-like members are provided with the recess 37 and the hole 43, but the recess and the hole are provided in the block-like covering A part may be provided to arrange the refrigerant circulation pipe 7 in a removable manner.

  Moreover, in the ground improvement method of the second embodiment, a covering iron plate may be used as the covering material as in the first embodiment without using the covering material provided with the recess and the hole, or the crushed stone may be used. You may use earth and sand.

  FIG. 8 is a view showing an example in which crushed stone or soil is used as the covering material 27. As shown in FIG. In each of the drawings shown in FIG. 8, the covering material 27 and the refrigerant circulation pipe 7 are installed in S112. That is, after the refrigerant circulation pipe 7 is installed on the surface 15 of the ground 1 in S112, the upper surface 8 of the refrigerant circulation pipe 7 and the surface 15 of the ground 1 are covered with a covering material 27 such as crushed stone or soil. If crushed stone or earth and sand is used as the covering material 27, cold heat hardly escapes from the frozen refrigerant or the ground 1 due to the heat insulating effect of the covering material.

  In the example shown in FIG. 8 (b), the base plate 29 is placed on the covering material 27. In the example shown in FIG. 8C, the pavement or the roadbed 39 is installed on the covering material 27. The floor plate 29, the pavement, and the roadbed 39 are installed, for example, between S104 and S107.

  In the example shown in FIG. 8, the covering material 27 may have a freezing range 28 indicated by a dotted line. In this case, it is assumed that soil in which water is contained in at least a part of the covering material 27 is used. In order to make at least a part of the covering material 27 contain soil containing water, in S112, the soil containing water in advance is installed as the covering material 27. Alternatively, after the earth and sand are installed as the covering material 27 in S112, water is dispersed to the earth and sand to contain water. As a result, when the freezing refrigerant is circulated in the refrigerant circulation pipe 7 and the freezing is started in S103, the soil containing water is frozen, and the freezing range 28 is also formed on the covering material 27. The freezing range 28 has a convex arch shape on the upper side due to cold heat from the lower side. The covering material 27 has increased strength against the load from above by the arch effect of the freezing range 28.

  In the second embodiment, the use of the improved ground is not limited, but as in the first embodiment, it may be used as a scaffold for a crane on a soft ground, or may be used as a temporary road or the like . For example, the example shown in FIG. 8C is suitable for use as a temporary road. Moreover, if a ballast is installed instead of pavement or the roadbed 39, it can be used for a temporary track.

  In the first and second embodiments, the upper surface 8 of the refrigerant circulation pipe 7 is covered with the covering material, but a heat insulation layer (not shown) is formed on the upper side surface of the refrigerant circulation pipe 7 and the upper surface of the heat insulation layer is It may be coated with a coating material. In the heat insulating layer, a heat insulating material is attached in advance to one surface of the refrigerant circulation pipe 7, and the surface to which the heat insulating material is attached in S102 of the first embodiment or S112 of the second embodiment is the upper surface 8. The refrigerant circulation pipe 7 is installed so that the surface on which the refrigerant circulation pipe 7 is exposed and the heat insulating material is not attached is the lower surface. The heat insulating layer is formed using a material whose thermal conductivity is lower than that of the lower surface of the refrigerant circulation pipe 7 which is a surface facing the ground. For this reason, by forming the heat insulating layer, cold heat hardly escapes from the upper side surface of the refrigerant circulation pipe 7.

  In S109 of the first and second embodiments, the circulation of the freezing refrigerant is stopped and the freezing range 21 is melted, but the heating range is circulated to the refrigerant circulation pipe 7 instead of the freezing refrigerant, and the freezing range 21 is frozen. May promote the melting of Thereby, the surface layer 19 of the ground 1 can be restored in a short time.

  In the first and second embodiments, the strength of the substantially central portion of the freezing range 21 is increased, but the distribution of the strength of the freezing range is not limited thereto. FIG. 9 is a diagram showing an example in which a frozen portion higher in strength than the center is formed in a portion off the center.

  In the example shown in FIG. 9, the position of the recess provided in the covering material 35a is adjusted so that the installation interval of the refrigerant circulation pipe 7 is narrow at a portion off the center and wide at the center portion. As a result, in the freezing range 21a, a frozen part having a higher strength than the center is formed in the part off the center. In the example shown in FIG. 9, when using a heavy machine or the like in the freezing range, the strength of the portion to which the load is applied by the heavy machine can be increased, so the outrigger 45 of the crane 25a is deviated from the center It is suitable for supporting the case.

  The method of forming a frozen portion having a strength higher than that of the center in a portion off the center is not limited to the method of adjusting the installation interval of the refrigerant circulation pipe 7 as described above. By circulating the refrigerant having a temperature lower than that of the refrigerant circulation pipe 7 disposed near the center to the refrigerant circulation pipe 7 disposed at the part deviated from the center, the part deviated from the center is stronger than the center You may form a freezing part.

  Further, the installation direction of the refrigerant circulation pipe 7 and the shape of the refrigerant circulation pipe are not limited to those shown in the first and second embodiments. FIG. 10 is a view showing an example of the cross section of the ground 1 on which the refrigerant circulation pipe is installed. In the example shown in FIG. 10A, the refrigerant circulation pipe 7 shown in FIG. 2C is installed near the surface 15 of the ground 1 so that the thickness direction is in the horizontal direction. In the example shown in FIG. 10 (b), the refrigerant circulating pipe 47 having a circular cross section is installed horizontally on the surface 15 of the ground 1. Also in the example shown in FIGS. 10 (a) and 10 (b), by circulating the frozen refrigerant horizontally in the vicinity of the surface 15 of the ground 1, the freezing range for strengthening the surface portion of the ground 1 can be shortened. Can be formed by

  In addition, it becomes possible for the piping for cooling circulation to shorten freezing time, and to improve the yield strength of a freezing range, so that a contact area with the ground 1 is large. Therefore, it is desirable that a portion of the cooling circulation piping be buried in the ground 1. Also, for example, in the case of using the refrigerant circulation pipe 47 having a circular cross section, the strength of the cooling circulation pipe 47 itself can also be utilized after freezing. In the present invention, the refrigerant circulation pipe may be removed when the frozen area is put into service, because the frozen ground alone has a sufficient yield strength without using the strength of the cooling circulation pipe.

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It is apparent that those skilled in the art can conceive of various modifications or alterations within the scope of the technical idea disclosed in the present application, and of course these also fall within the technical scope of the present invention. It is understood.

DESCRIPTION OF SYMBOLS 1 ...... Ground 3 ...... Planned frozen range 5 ...... Crane installation location 7, 7a, 7b, 47 ...... Refrigerant circulation piping 8 ...... Top surface 9, 9b, 31 ...... Supply piping 11 11b, 33 ......... Return piping 13, 13a, 13b ... ... Connection piping 15 ... ... Surface 17 ... ... Refrigerant circulation path 19 ... ... Surface layer 21, 21a, 28 ... ... Freezing range 23, 27, 35, 35a, 41 ...... Coating material 25, 25a ...... Crane 29 ...... Floor plate 31a, 33a ...... Branch pipe 37 ...... Recession 39 ...... Pavement or roadbed 43 ...... Hole 45 ......... Outrigger 49 ......... Thickness

Claims (12)

Installing a refrigerant circulation pipe in the horizontal direction near the surface of the ground;
A step b of circulating a frozen refrigerant through the refrigerant circulation pipe to freeze the frozen area of the surface layer portion of the ground;
Ground improvement method characterized by having.   The ground improvement construction method according to claim 1, wherein a covering material which covers an upper surface of the refrigerant circulation pipe and a surface of the ground is disposed.   The covering material is plate-like or block-like, and a recess or a hole is provided at a predetermined location of the covering material, and the refrigerant circulation pipe is detachably disposed in the recess or the hole. The ground improvement method according to claim 2, wherein the covering material and the refrigerant circulation pipe are integrated.   The ground according to claim 2 or 3, wherein at least a part of the covering material is earth and sand containing water, and the frozen refrigerant is circulated in the refrigerant circulation pipe to freeze the earth and sand. Improvement method.   The ground improvement construction method according to any one of claims 1 to 4, wherein the refrigerant circulation pipe is an aluminum extruded product provided with a refrigerant circulation passage.   6. The method according to any one of claims 1 to 5, wherein in the step a, the plurality of refrigerant circulation pipes are arranged at predetermined intervals in a direction orthogonal to the pipe axis direction and connected in series. Ground improvement method described in.   6. The method according to any one of claims 1 to 5, wherein in the step a, the plurality of refrigerant circulation pipes are arranged in parallel at predetermined intervals in a direction orthogonal to the pipe axis direction. Ground improvement method described in.   6. The method according to any one of claims 1 to 5, wherein in the step a, the plurality of refrigerant circulation pipes are disposed at predetermined intervals in the direction of the pipe axis and in the direction orthogonal to the pipe axis. Ground improvement method.   The ground improvement method according to any one of claims 1 to 8, wherein a heat insulating layer is formed on the upper side surface of the refrigerant circulation pipe.   10. The method according to any one of claims 1 to 9, further comprising a step (c) of circulating heat through the refrigerant circulation pipe after the step b to promote melting of the freezing range. Ground improvement method.   The ground improvement construction method according to any one of claims 1 to 10, wherein, in the step b, a frozen portion having a higher strength than the center is formed in a portion out of the center of the freezing range. A plate-like or block-like covering material that covers the surface of the ground,
A recess or a hole is provided at a predetermined location, and a refrigerant circulation pipe horizontally disposed in the vicinity of the surface of the ground is detachably disposed in the recess or the hole, whereby the refrigerant circulation pipe and A covering material characterized in that it is integrated.

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