JP6913583B2 - Ground improvement method - Google Patents

Description

The present invention relates to a ground improvement construction method.

When a heavy structure such as a heavy machine is used on the ground of soft cohesive soil, if the earth and sand or crushed stone are spread directly on the ground, the soft soil may not be able to support the weight of the earth and sand, crushed stone, heavy machine or the like. Therefore, conventionally, a solidifying material such as cement has been added to soft soil and mixed, and the surface layer portion of the ground has been strengthened by cement-improved soil.

Another method of strengthening the surface layer of the ground is to lay a bag body in a grid pattern on a planar member laid on the ground, fill the bag body with a fluid solidifying material and solidify it, and make it rigid on the ground. There was a method of forming a reinforcing body (see, for example, Patent Document 1). There is also a method in which a frozen pipe is driven vertically into the ground to a predetermined depth to form a glisol layer, and a receiving plate is laid on the upper surface of the glisol layer (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2012-31596 Special Fair 7-882 Gazette

However, when the surface layer of the ground was strengthened by using cement-improved soil in areas such as riverbeds and leased land, it was not easy to remove the strengthened part, and it was difficult to restore the current state of the ground. In addition, the removed cement-improved soil had to be treated as industrial waste. On the other hand, the method of forming a rigid reinforcing body and the method of driving a freezing pipe in the vertical direction to form a gelisol layer are suitable for application to riverbeds and leased land because it is relatively easy to restore the current state after work. However, it took days to complete the construction.

The present invention has been made in view of the above problems, it is an object of the present invention, it is possible construction in a short period of time to provide a ground improvement construction method is easy current recovery after work be.

The first invention for achieving the above-mentioned object is a step a of horizontally installing a refrigerant circulation pipe near the surface of the ground, and a surface layer of the ground by circulating frozen refrigerant through the refrigerant circulation pipe. A step b for freezing the freezing range of the portion is provided , and a covering material for covering the upper surface of the refrigerant circulation pipe and the surface of the ground is arranged, and the covering material is plate-shaped or block-shaped, and the covering is provided. recesses or holes at predetermined positions are provided in the timber, by the refrigerant circulation pipe is detachably disposed in the recess or hole, Ru is integrated with the covering material and the pipe refrigerant circulation This is a ground improvement method characterized by this.
The second invention is a step a of horizontally installing a refrigerant circulation pipe near the surface of the ground, and a step of circulating frozen refrigerant through the refrigerant circulation pipe to freeze the freezing range of the surface layer portion of the ground. This is a ground improvement method comprising b and, wherein a steel covering material covering the upper surface of the refrigerant circulation pipe and the surface of the ground is arranged in the step a.
The third invention is a step a of horizontally installing a refrigerant circulation pipe near the surface of the ground, and a step of circulating frozen refrigerant through the refrigerant circulation pipe to freeze the freezing range of the surface layer portion of the ground. B, and a ground improvement characterized in that, in the step a, earth and sand containing at least a part of water is arranged as a covering material for covering the upper surface of the refrigerant circulation pipe and the surface of the ground. It is a construction method.
The fourth invention is a step a of horizontally installing a refrigerant circulation pipe having a heat insulating material on the upper surface near the surface of the ground, and a surface layer portion of the ground by circulating frozen refrigerant through the refrigerant circulation pipe. This is a ground improvement method comprising a step b of freezing the freezing range of the above, wherein the upper surface of the heat insulating material and the surface of the ground are covered with a covering material.

By installing a 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 period of time. Further, by thawing the freezing range and removing the refrigerant circulation pipe, the current state can be easily restored after the work.

In the first to fourth inventions, covering material covering the upper surface and the surface of the ground of the piping refrigerant circulation Ru is located.
If a steel member such as an iron plate is provided as a covering material on the upper surface of the refrigerant circulation pipe or the surface of the ground, the heat conduction effect of the covering material efficiently cools the frozen refrigerant in the refrigerant circulation pipe to the ground. Can be transmitted to. Further, if crushed stone or earth and sand are provided as the covering material, the heat insulating effect of the covering material makes it difficult for cold heat to escape from the frozen refrigerant and the ground.

In the first invention, the covering material is plate-shaped or block-shaped, recesses or holes are provided at predetermined positions of the covering material, and the refrigerant circulation pipe is detachably arranged in the recesses or holes. by being, said dressing and said pipe and the coolant circulation Ru integrated.
As a result, the covering material and the refrigerant circulation pipe can be installed near the surface of the ground in an integrated state.

In the third invention, in the step a, earth and sand containing at least a part of water is arranged as a covering material for covering the upper surface of the refrigerant circulation pipe and the surface of the ground. Then, Ru frozen the sediment by circulating the freezing refrigerant to the piping coolant circulation.
If the earth and sand soaked in water are frozen so that the upper side becomes convex by the cooling heat from the lower side, the bearing capacity of the covering material can be increased against the load from the upper side by the arch effect.

It is desirable that the refrigerant circulation pipe is an extruded aluminum product provided with a refrigerant circulation path.
If an extruded aluminum product is used, it is possible to obtain a refrigerant circulation pipe that is lightweight and has excellent thermal conductivity.

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

Alternatively, in the step a, the plurality of the refrigerant circulation pipes may be arranged in parallel at predetermined intervals in a direction orthogonal to the pipe axis direction.
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 the refrigerant circulation pipes may be arranged at predetermined intervals in the pipe axis direction and in the direction orthogonal to the pipe axis.
If the installation intervals of the refrigerant circulation pipes in the pipe axis direction and the direction orthogonal to the pipe axis are appropriately set, the freezing range can be frozen by effectively utilizing the cold heat.

In the fourth invention, in the step a, the refrigerant circulation pipe with the heat insulating material attached to the upper surface is installed in the horizontal direction.
If a heat insulating layer having a lower thermal conductivity than the lower side surface facing the ground is formed on the upper side surface of the refrigerant circulation pipe, it becomes difficult for the cold heat of the frozen refrigerant to escape upward.

After the step b, a step c may be further provided in which heat is circulated in the refrigerant circulation pipe to promote melting in the freezing range.
As a result, the freezing range can be thawed in a short period of time, and the period required for restoration of the current state can be further shortened.

In the step b, a frozen portion having a higher strength than the center may be formed in a portion of the freezing range outside the center.
As a result, when a heavy machine such as a crane is used in the freezing range, the strength of the portion to which the heavy machine is applied can be increased.

According to the present invention, it is possible construction in a short period of time, it is possible to provide a ground improvement construction method is easy current recovery after operation.

The figure which shows the flowchart of the ground improvement method The figure which shows the installation method of the refrigerant circulation pipe 7 and the like. The figure which shows the example which connected the plurality of refrigerant circulation pipes 7 in parallel The figure which shows the other arrangement example of the refrigerant circulation pipe The figure which shows the flowchart of the ground improvement method The figure which shows the installation method of the refrigerant circulation pipe 7 and the like. The figure which shows the example which used the covering material 41 which has a hole 43 The figure which shows the example which used crushed stone and earth and sand as a covering material 27 The figure which shows the example which formed the frozen part which is stronger than the center in the part off the center. The figure which shows the example of the cross section of the ground 1 which installed the refrigerant circulation pipe.

Hereinafter, the first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a flowchart of a ground improvement method. FIG. 2 is a diagram showing an installation method and the like of the refrigerant circulation pipe 7. 2 (a) and 2 (b) are views showing the arrangement of the refrigerant circulation pipe 7, and FIG. 2 (b) is a cross-sectional view taken along the arrow CC shown in FIG. 2 (a). FIG. 2 (c) is a perspective view of the refrigerant circulation pipe 7, FIG. 2 (d) is a diagram showing a state in which the ground 1 is frozen, and FIG. 2 (e) is a 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 the bearing capacity of the scaffolding of the crane on the soft ground. Hereinafter, the ground improvement method of the first embodiment will be described with reference to 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. 2A and 2B, the refrigerant circulation pipe 7 is horizontally installed on the surface 15 of the planned freezing range 3 of the ground 1 which is soft ground. The refrigerant circulation pipes 7 are arranged at predetermined intervals in the pipe axis direction, 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 range 3 is set, for example, with a margin of 1 m around the crane installation location 5.

The refrigerant circulation pipe 7 is connected in series by the connecting pipe 13. A supply pipe 9 is connected to one end of a plurality of refrigerant circulation pipes 7 connected in series, and a 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 in the refrigerant circulation pipe 7 to start freezing (S103). As shown in FIG. 2A, the frozen refrigerant flows from a refrigerant circulator (not shown) into the refrigerant circulation pipe 7 via the supply pipe 9 as shown by arrow A1. Then, it passes through the plurality of refrigerant circulation pipes 7 and the connecting pipes 13 connected in series, and returns to the refrigerant circulation machine (not shown) via the return pipe 11 as shown by the arrow B1.

As shown in FIG. 2C, the refrigerant circulation pipe 7 is a plate-shaped member and is an extruded aluminum product. The refrigerant circulation pipe 7 has a plurality of refrigerant circulation paths 17 which are flow paths of frozen refrigerant inside. The frozen refrigerant circulates horizontally in the refrigerant circulation path 17 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 frozen refrigerant was started in S103, freezing is confirmed (S104). In S104, as shown in FIG. 2D, it is confirmed that the freezing range 21 is formed on the surface layer portion 19 of the ground 1. It is desirable to determine the timing of confirming freezing 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, and the supply pipe is used. The temperature difference between the inlet of 9 and the outlet of the return pipe 11 is measured, the elastic coefficient is measured by falling ball exploration, the strength is measured by penetrating the cone, and the like.

After confirming freezing in S104, the covering material 23 is laid (S105), the crane 25 is installed, and the settlement measurement is performed (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 the covering material 23. The covering material 23 is, for example, an iron plate. In S106, as shown in FIG. 2E, the crane 25 is installed on the covering material 23 laid in S105, and the amount of subsidence in the freezing range 21 is measured.

If the settlement amount 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. When the subsidence amount measured in S106 clears the reference value, the crane 25 is installed on the freezing range 21 and put into service as shown in FIG. 2 (e) (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 frozen refrigerant is stopped to thaw the freezing range 21, 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.

As described above, in the first embodiment, the surface layer portion 19 of the ground 1 is strengthened by horizontally installing the refrigerant circulation pipe 7 near the surface 15 of the ground 1 and circulating the frozen refrigerant in the horizontal direction. The freezing range 21 for this purpose can be formed in a short period of time, the trafficability of the ground 1 is improved, and the bearing capacity for preventing the heavy machinery from tipping over can be secured. Further, by thawing the freezing range 21 and removing the refrigerant circulation pipe 7 and the covering material 23, the ground 1 can be easily restored to the present state after the work.

In the first embodiment, since a lightweight extruded aluminum product is used, it is easy to transport the refrigerant circulation pipe 7 to the site and install it on the ground 1. Further, since the refrigerant circulation pipe 7 of the extruded aluminum product has excellent thermal conductivity, the cold heat of the frozen refrigerant can be efficiently transferred to the surface layer portion 19 of the ground 1 during operation.

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, the direction of freezing in the freezing range 21 can be specified. Therefore, the connection in series is useful when the soft ground on the riverbank is frozen from the side far from the riverbank.

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

FIG. 3 is a diagram showing an example in which a plurality of refrigerant circulation pipes 7 are connected in parallel. In the example shown in FIG. 3, one end of a plurality of refrigerant circulation pipes 7 arranged at predetermined intervals in a direction orthogonal to the pipe axis direction is connected to a branch pipe 31a branched from the supply pipe 31. The other end is connected to the branch pipe 33a branched from the return pipe 33, respectively. As a result, a 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, in S103, the frozen refrigerant is supplied from a refrigerant circulator (not shown) via the supply pipe 31 and the branch pipe 31a as shown by arrow A2. It flows into the circulation pipe 7. Then, as shown by the arrow B2, the refrigerant returns to the refrigerant circulator (not shown) via the branch pipe 33a and the return pipe 33.

If the frozen refrigerant is simultaneously circulated in 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 if a large number of refrigerant circulation pipes 7 are installed in a wide range, a plurality of refrigerant circulation pipes 7 can be supplied to the supply pipe 31. It can be connected to the return pipe 33 at the same time and is easy to install.

FIG. 4 is a diagram showing another arrangement example of the refrigerant circulation pipe. In the example shown in FIG. 4A, the refrigerant circulation pipe 7a shown in FIG. 2C is cut to a length of about 1 m, and the refrigerant circulation pipe 7a is designated in the pipe axis direction and in the direction orthogonal to the pipe axis. Place them at intervals. Then, all the refrigerant circulation pipes 7a are connected in series by using the connecting pipe 13 and the connecting pipe 13a. In S103, the frozen refrigerant flows from the supply pipe 9 into the refrigerant circulation pipe 7a as shown by the arrow A3, passes through the plurality of refrigerant circulation pipes 7a, the connecting pipe 13, and the connecting pipe 13a connected in series, and the arrow indicates. Return to the return pipe 11 as shown in B3.

In the example shown in FIG. 4B, in addition to the refrigerant circulation pipe 7 shown in FIG. 2A, a plurality of refrigerant circulation pipes 7b are provided at predetermined intervals in the pipe axis direction of the refrigerant circulation pipe 7. And place it. The plurality of refrigerant circulation pipes 7b are connected in series by the connecting pipe 13b. A supply pipe 9b is connected to one end of a plurality of refrigerant circulation pipes 7b connected in series, and a return pipe 11b is connected to the other end.

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

As shown in each figure of FIG. 4, if the installation intervals of the refrigerant circulation pipes in the pipe axis direction and the direction orthogonal to the pipe axis are appropriately set according to the range to be frozen, the cold heat can be effectively used. The freezing area can be frozen.

In the example shown in FIG. 4A, the planned freezing range 3 is set by transmitting cold heat from the location where the refrigerant circulation pipe 7a is installed to the ground 1 and not transmitting cold heat from the location where the connecting pipe 13a is installed. It can be partially cooled and the freezing range can be efficiently frozen with a small amount of heat. Even when a long refrigerant circulation pipe 7 is used as shown in FIGS. 2A and 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. By preventing the cold heat from being transmitted from the portion around which the heat insulating material is wound to the ground 1, the same effect as the example shown in FIG. 4A can be obtained.

In the ground improvement method of the first embodiment, crushed stone, earth and sand, or the like may be used as the covering material 23 instead of using the iron plate.

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

FIG. 5 is a diagram showing a flowchart of the ground improvement method. FIG. 6 is a diagram showing an installation method and the like of the refrigerant circulation pipe 7. 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 circulation pipe 7, and FIG. 6 (c) is the refrigerant circulation pipe 7 and the covering material. FIG. 6 (d), which shows the arrangement of 35, is a diagram showing a state in which the ground 1 is frozen.

Hereinafter, the ground improvement method of the second embodiment will be described with reference to 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 steel plate-shaped member, and groove-shaped recesses 37 are provided on one surface at predetermined intervals. As shown in FIG. 2B, a refrigerant circulation pipe 7 is installed in the recess 37 of the covering material 35. The refrigerant circulation pipe 7 can be attached to and detached 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. 6A and 6B so that the surface on the side where the recess 37 is formed is in contact with the ground 1, and the refrigerant circulation pipe 7 is installed. Covers the upper surface 8 and the surface 15 of the ground 1.

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

After S112, the frozen refrigerant is circulated in the refrigerant circulation pipe 7 to start freezing (S103). The frozen refrigerant circulates horizontally 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 frozen refrigerant was started in S103, freezing is confirmed (S104). In S104, as shown in FIG. 6D, it is confirmed that the freezing range 21 is formed on the surface layer portion 19 of the ground 1. The timing and method for confirming freezing are the same as in S104 of the first embodiment.

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

As described above, in the second embodiment, the surface layer portion 19 of the ground 1 is strengthened by horizontally installing the refrigerant circulation pipe 7 near the surface 15 of the ground 1 and circulating the frozen refrigerant in the horizontal direction. The freezing range 21 for this purpose can be formed in a short period of time, the trafficability of the ground 1 is improved, and the bearing capacity for preventing the heavy machinery from tipping over can be secured. Further, by thawing the freezing range 21 and removing the refrigerant circulation pipe 7 and the covering material 35, the ground 1 can be easily restored to the present state after the work.

In the second embodiment, by integrating the covering material 35 and the refrigerant circulation pipe 7, the covering material 35 and the refrigerant circulation pipe 7 can be simultaneously installed and removed near the surface 15 of the ground 1. Further, if the refrigerant circulation pipe 7 can be attached to and detached from the covering material 35, the refrigerant circulation pipe 7 can be removed and diverted after use. Further, by arranging the refrigerant circulation pipe 7 in the recess 37 of the steel covering material 35, the heat conduction effect of the covering material 35 efficiently transfers cold heat from the refrigerant circulation pipe 7 to the ground 1 via the covering material 35. I can tell.

In the second embodiment, the refrigerant circulation pipe 7 is arranged in the recess 37 provided in the plate-shaped covering material 35, but the refrigerant circulation pipe 7 may be arranged in the hole. FIG. 7 is a diagram showing an example in which a covering material 41 having a 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 diagram showing a state in which the ground 1 is frozen.

As shown in FIG. 7A, the covering material 41 is a steel plate-shaped member, and holes 43 are provided at substantially the center in the thickness 49 direction at predetermined intervals. A refrigerant circulation pipe 7 is installed in the hole 43 of the covering material 41. That is, the covering material 41 covers the entire outer circumference of the refrigerant circulation pipe 7. The refrigerant circulation pipe 7 can be attached to and detached 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 pipe 7 may be connected in series by a connecting pipe as shown in FIG. 2A, or may be connected in parallel by a branch pipe as shown in FIG.

Even when the refrigerant circulation pipe 7 and the covering material 41 are integrated by 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 period of time. The same effect as that of the second embodiment can be obtained.

In the second embodiment and the example shown in FIG. 7, the covering material 35 and the covering material 41, which are steel plate-shaped materials, are provided with the recesses 37 and the holes 43, but the block-shaped covering material is provided with the recesses and holes. A portion may be provided so that the refrigerant circulation pipe 7 can be detachably arranged.

Further, in the ground improvement method of the second embodiment, a covering material provided with recesses and holes may not be used, and a paving iron plate may be used as the covering material as in the first embodiment, or crushed stone. Or earth and sand may be used.

FIG. 8 is a diagram showing an example in which crushed stone or earth and sand are used as the covering material 27. In each figure shown in FIG. 8, the covering material 27 and the refrigerant circulation pipe 7 are installed in S112. That is, in S112, after the refrigerant circulation pipe 7 is installed on the surface 15 of the ground 1, 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 earth and sand. If crushed stone or earth and sand are used as the covering material 27, cold heat is less likely to escape from the frozen refrigerant and the ground 1 due to the heat insulating effect of the covering material.

In the example shown in FIG. 8B, the iron plate 29 is installed on the covering material 27. In the example shown in FIG. 8C, a pavement or a roadbed 39 is installed on the covering material 27. The paving iron plate 29, the pavement and the roadbed 39 are installed between S104 and S107, for example.

In the example shown in FIG. 8, the freezing range 28 shown by the dotted line may be formed on the covering material 27. In this case, it is assumed that earth and sand in which at least a part of the covering material 27 is moistened is used. In order to make at least a part of the covering material 27 moistened earth and sand, the earth and sand soaked in water in advance is installed as the covering material 27 in S112. Alternatively, in S112, after the earth and sand are installed as the covering material 27, water is sprayed on the earth and sand to moisten the earth and sand. As a result, when the frozen refrigerant is circulated in the refrigerant circulation pipe 7 in S103 to start freezing, the earth and sand containing water freezes, and the covering material 27 also forms a freezing range 28. The freezing range 28 has an arch shape with a convex upper side due to cold heat from below. The covering material 27 has an increased strength against a load from above due to 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 scaffolding for a crane on soft ground, or as a temporary road or the like. .. For example, the example shown in FIG. 8C is suitable for use as a temporary road. Further, if a ballast is installed instead of the 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 a covering material, but a heat insulating layer (not shown) is formed on the upper side surface of the refrigerant circulation pipe 7, and the upper surface of the heat insulating layer is formed. It may be coated with a covering material. In the heat insulating layer, a heat insulating material is previously attached to one surface of the refrigerant circulation pipe 7, and in S102 of the first embodiment and S112 of the second embodiment, the surface to which the heat insulating material is attached becomes the upper surface 8. The refrigerant circulation pipe 7 is installed so that the surface on which the heat insulating material is not attached and the refrigerant circulation pipe 7 is exposed is the lower surface. The heat insulating layer is formed by using a material having a lower thermal conductivity than the lower surface of the refrigerant circulation pipe 7, which is a surface facing the ground. Therefore, by forming the heat insulating layer, it becomes difficult for cold heat to escape from the upper side surface of the refrigerant circulation pipe 7.

In S109 of the first and second embodiments, the circulation of the frozen refrigerant was stopped to thaw the freezing range 21, but the freezing range 21 was circulated in the refrigerant circulation pipe 7 instead of the frozen refrigerant. May accelerate the melting of the As a result, the surface layer portion 19 of the ground 1 can be restored in a shorter period of time.

In the first and second embodiments, the intensity of the substantially central portion of the freezing range 21 is increased, but the distribution of the intensity of the freezing range is not limited to this. FIG. 9 is a diagram showing an example in which a frozen portion having a higher strength than the center is formed in a portion deviated from 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 in the portion deviated from the center and wide in the central portion. As a result, in the freezing range 21a, a frozen portion having a higher strength than the center is formed in the portion deviated from the center. In the example shown in FIG. 9, when a heavy machine or the like is used in the freezing range, the strength of the portion to which the heavy machine is applied can be increased. Therefore, the outrigger 45 of the crane 25a is located outside the center of the freezing range 21a. It is suitable for supporting.

The method of forming a frozen portion having a strength higher than that of the center in the portion deviated from the center is not limited to the method of adjusting the installation interval of the refrigerant circulation pipe 7 as described above. By circulating a refrigerant having a lower temperature than the refrigerant circulation pipe 7 arranged near the center in the refrigerant circulation pipe 7 arranged in the portion deviated from the center, the strength is higher than that in the center in the portion deviated from the center. A frozen portion may be formed.

Further, the direction of installation of the refrigerant circulation pipe 7 and the shape of the refrigerant circulation pipe 7 are not limited to those shown in the first and second embodiments. FIG. 10 is a diagram showing an example of a cross section of the ground 1 in 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 horizontal. In the example shown in FIG. 10B, the refrigerant circulation pipe 47 having a circular cross section is installed horizontally on the surface 15 of the ground 1. Also in the examples shown in FIGS. 10 (a) and 10 (b), the freezing range for strengthening the surface layer portion of the ground 1 is shortened for a short period of time by circulating the frozen refrigerant horizontally near the surface 15 of the ground 1. Can be formed with.

The larger the contact area of the cooling circulation pipe with the ground 1, the shorter the freezing time and the better the yield strength of the freezing range. Therefore, it is desirable that a part of the cooling circulation pipe is buried in the ground 1. Further, for example, when the refrigerant circulation pipe 47 having a circular cross section is used, the strength of the cooling circulation pipe 47 itself can be used after freezing. In the present invention, since the frozen ground alone has sufficient yield strength without utilizing the strength of the cooling circulation pipe, the refrigerant circulation pipe may be removed when the freezing range is put into service.

Although 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 clear that a person skilled in the art can come up with various modified examples or modified examples within the scope of the technical idea disclosed in the present application, and these also naturally belong to the technical scope of the present invention. Understood.

1 ………… Ground 3 ………… Planned freezing 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 ……… Connecting piping 15 ……… Surface 17 ……… Refrigerant circulation path 19 ……… Surface layer 21, 21a, 28 ……… Freezing range 23, 27, 35, 35a, 41 ………… Covering material 25, 25a ………… Crane 29 ………… Laying iron plate 31a, 33a ………… Branch pipe 37 ………… Recessed 39 ………… Pavement and roadbed 43 ………… Hole 45 ……… Outrigger 49 ……… Thickness

Claims (10)

Step a of installing the refrigerant circulation pipe in the horizontal direction near the surface of the ground,
A step b in which a frozen refrigerant is circulated in the refrigerant circulation pipe to freeze the freezing range of the surface layer portion of the ground.
Equipped with
A covering material covering the upper surface of the refrigerant circulation pipe and the surface of the ground is arranged.
The covering material is plate-shaped or block-shaped, a recess or a hole is provided at a predetermined portion of the covering material, and the refrigerant circulation pipe is detachably arranged in the recess or the hole. A ground improvement method characterized in that the covering material and the refrigerant circulation pipe are integrated. Step a of installing the refrigerant circulation pipe in the horizontal direction near the surface of the ground,
A step b in which a frozen refrigerant is circulated in the refrigerant circulation pipe to freeze the freezing range of the surface layer portion of the ground.
Equipped with
A ground improvement method comprising arranging a steel covering material that covers the upper surface of the refrigerant circulation pipe and the surface of the ground in the step a. Step a of installing the refrigerant circulation pipe in the horizontal direction near the surface of the ground,
A step b in which a frozen refrigerant is circulated in the refrigerant circulation pipe to freeze the freezing range of the surface layer portion of the ground.
Equipped with
The ground improvement method, characterized in that, in the step a, earth and sand containing at least a part of water is arranged as a covering material for covering the upper surface of the refrigerant circulation pipe and the surface of the ground. Step a of horizontally installing a refrigerant circulation pipe with a heat insulating material on the upper surface near the surface of the ground,
A step b in which a frozen refrigerant is circulated in the refrigerant circulation pipe to freeze the freezing range of the surface layer portion of the ground.
Equipped with
A ground improvement method characterized in that the upper surface of the heat insulating material and the surface of the ground are covered with a covering material. The ground improvement method according to any one of claims 1 to 4, wherein the refrigerant circulation pipe is an extruded aluminum product provided with a refrigerant circulation path. Any one of claims 1 to 5, wherein in the step a, a plurality of the refrigerant circulation pipes are arranged in a direction orthogonal to the pipe axis direction at a predetermined interval and connected in series. Ground improvement method described in. Any one of claims 1 to 5, wherein in the step a, a plurality of the refrigerant circulation pipes are arranged in a direction orthogonal to the pipe axis direction at a predetermined interval and connected in parallel. Ground improvement method described in. The method according to any one of claims 1 to 5, wherein in the step a, the plurality of the refrigerant circulation pipes are arranged at predetermined intervals in the pipe axis direction and the direction orthogonal to the pipe axis. Ground improvement method. The method according to any one of claims 1 to 8, further comprising a step c in which heat is circulated in the refrigerant circulation pipe to promote melting of the freezing range after the step b. Ground improvement method. The ground improvement method according to any one of claims 1 to 9, wherein in the step b, a frozen portion having a strength higher than that of the center is formed in a portion of the freezing range outside the center.

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