JP-7857188-B2 - Freezing system and freezing structure construction method

Inventors

• 吉田 輝
• 佐藤 一成
• 田中 俊行
• 大野 進太郎
• 江崎 太一

Assignees

• 鹿島建設株式会社

Dates

Publication Date

20260512

Application Date

20220824

Claims (4)

1. Multiple freezing pipes are placed underground, through which a cooling medium flows, A casing into which multiple freezing pipes are inserted within a predetermined range from the ground surface, It is equipped with, Inside the casing, a plurality of the freezing tubes are clustered together, and below the casing, they are arranged so that the spacing between the plurality of freezing tubes increases . A freezing system characterized in that a borehole is formed below the casing into which each of the freezing pipes is inserted, and the inside of the borehole is filled with a heat transfer member .
2. The freezing system according to claim 1, characterized in that insulating means are arranged inside the casing and on the outer periphery of the plurality of freezing tubes.
3. The freezing system according to claim 1, characterized in that the freezing tube is an aluminum microchannel.
4. The process involves installing the casing into the ground to a predetermined depth, The process involves forming multiple boreholes below the casing so as to spread outward from the center, The process involves inserting the freezing pipes into each of the excavated holes via the casing, The process involves flowing a cooling medium through the freezing pipe to freeze a predetermined area underground, It is equipped with , A method for constructing a frozen structure, characterized in that, in the step of forming the borehole, the borehole is drilled while filling it with a filling liquid that functions as a heat transfer member .

Description

This invention relates to a freezing system and a method for constructing a frozen structure. The freezing method, as shown in Figure 8(a), involves installing freezing pipes 102 in the ground 101 and circulating a cooling medium to freeze the moisture in the ground, thereby forming frozen soil 103. This frozen soil 103 is then used as a watertight wall, a shear wall, etc. If the temperature of the cooling medium is too low or the freezing period is too long, freezing expansion will cause the ground 101 surrounding the frozen soil 103 to be consolidated in the direction indicated by the arrow. In the shallow layers of the ground 101, the soil pressure is lower, resulting in greater freezing expansion and consolidation than in the deeper layers. However, consolidation is an irreversible change, so even after freezing ends and the frozen soil 103 thaws, the surrounding consolidated portion does not return to its original position. Therefore, as shown in Figure 8(b), the thawed portion 105, which contains a large amount of moisture, undergoes self-weight consolidation, resulting in the formation of a settled area 104. To suppress settlement after thawing of frozen soil, measures such as limiting the freezing area using limited freezing pipes (see, for example, Patent Document 1) and increasing the rigidity of the ground through ground improvement methods such as jet grouting can be employed. Utility Model Application No. 55-47957 A vertical cross-sectional view of the freezing system 6.A horizontal cross-sectional view of the freezing system 6.Cross-sectional view of freezing pipe 3.A diagram showing the state of drilling the borehole 4.This diagram shows the state after drilling the borehole 4.A vertical cross-sectional view of the freezing system 6 in operation.A vertical cross-sectional view of the freezing system 6a.A diagram illustrating the freezing method. The first embodiment of the present invention will be described in detail below with reference to the drawings. Figure 1 is a vertical cross-sectional view of the freezing system 6, and Figure 2 is a horizontal cross-sectional view of the freezing system 6. Figure 2(a) shows a cross-section along line A-A in Figure 1, and Figure 2(b) shows a cross-section along line B-B in Figure 1. Figure 3 is a cross-sectional view of the freezing pipe 3. As shown in Figure 1, the freezing system 6 consists of freezing pipes 3, a casing 2, an insulating member 16, a heat transfer member 12, etc. The freezing pipes 3 are pipes through which a cooling medium flows to form frozen soil in the ground 1. The casing 2 is positioned from the surface of the ground 1 to a predetermined depth, and the same number of boreholes 4 as the freezing pipes 3 are formed below the casing 2. Each freezing pipe 3 is inserted into the inside of the casing 2 and into the boreholes 4. As shown in Figures 1 and 2(a), multiple freezing tubes 3 are arranged together inside the casing 2. Inside the casing 2, an insulating member 16, which serves as an insulating means, is placed around the outer circumference of each freezing tube 3. As shown in Figures 1 and 2(b), the boreholes 4 below the casing 2 are formed such that the spacing between the straight sections 18 is increased by curved sections 17 that extend outward from the casing 2. That is, the curved sections 17 of the multiple boreholes 4 are arranged radially around the casing 2 in a plan view. The multiple freezing pipes 3 are arranged below the casing 2, inserted into different boreholes 4, so that the spacing between them increases. The boreholes 4 are filled with a heat transfer material 12. The heat transfer material 12 is, for example, water or cement bentonite, and is filled to facilitate the transfer of the cold and heat from the cooling medium flowing through the freezing pipes 3 to the ground 1. In the ground 1, the area from the surface to a predetermined depth is the freezing suppression range 5, where the formation of frozen soil is suppressed by the freezing pipe 3. In the freezing system 6, it is desirable that the curved section 17 of the excavation hole 4 is located below the freezing suppression range 5, and the straight section 18 is located below the freezing suppression range 5. As shown in Figure 3, the freezing tube 3 is, for example, an aluminum microchannel manufactured as an aluminum extruded product. Multiple refrigerant circulation channels 7 are provided in parallel within the freezing tube 3. Next, the method for constructing a frozen structure using the freezing system 6 will be described. Figure 4 is a vertical cross-sectional view showing the drilling of the borehole 4, and Figure 5 is a vertical cross-sectional view showing the completed drilling of the borehole 4. To construct a frozen structure using the freezing system 6, first, as shown in Figure 4, the casing 2 is erected in the ground 1 to a predetermined depth. Then, a drilling rod 8, equipped with a drilling section 9 at its tip, is passed throu