Underground heat exchange device and method for building underground heat exchange device

Abstract

To provide an underground heat exchange device in which a heat exchange between a bore hole and a hole wall is efficiently performed.SOLUTION: The present invention includes: a water-proof cylindrical bag body 5 which has a bottomed cylindrical shape with flexibility, and is arranged by extending in a vertical direction inside a bore hole 2 in which an excavated earth and sand mixed liquid 3 containing a hardening material is stored inside; a vertically extending float resistance member 12 which extends in a vertical direction along an outer face 6 of the cylindrical bag body 5 in the bore hole 2 and in which a lower end part of the resistance member is connected to a lower end part of the bag body of the cylindrical bag body 5; and a reactive force member 15 which supports such that an upper end of the float resistance member 12 does not move in an upward direction. An outer diameter of the cylindrical bag body 5 which is expanded to maximum and in which a thermal medium liquid 17 having a smaller specific gravity than the excavated earth and sand mixed liquid is smaller than an inner diameter of the bore hole 2. The buoyancy acting on the cylindrical bag body 5 in which the thermal medium liquid is stored is resisted by the float resistance member 12 in a state of stretching between the lower end part 9 of the bag body and the reactive force member 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an underground heat exchanger and a method for constructing an underground heat exchanger. [Background technology]

[0002] As an example of a geothermal heat exchanger that uses a borehole formed by injecting drilling fluid into the ground to excavate and agitate it, there is provided a borehole-type heat storage device described in Patent Document 1.

[0003] The borehole-type heat storage device is equipped with a pile-shaped heat medium container formed by driving a mud pump to drain muddy water from a borehole formed by excavating the ground, inserting a flexible bag made of a watertight sheet material into the borehole, inflating the bag by injecting a heat medium from the bottom, and then adhering the bag to the wall of the borehole due to the pressure generated when the heat medium is injected.

[0004] Incidentally, paragraph 0011 of Patent Document 1 states that, with regard to the adhesion of the borehole to the hole wall surface, the borehole wall may be uneven to the extent that it does not lead to wall collapse. Here, a borehole refers to a hole drilled into the ground for geothermal energy extraction. Depending on the condition of the geological layer, the hole may be drilled in hard ground such as bedrock or in easily collapsible ground such as silt. As stated in paragraph 0011, the degree of unevenness of the borehole wall targeted by Patent Document 1 must be such that the bag can be flexible enough to adhere to the hole wall surface. If the unevenness is too great and the bag cannot adhere to the hole wall, an insulating space will be created in that area, resulting in reduced heat exchange efficiency. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-317389 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention was developed in consideration of the above-mentioned problems of the conventional technology, and aims to provide an underground heat exchanger that can efficiently exchange heat with the borehole wall without being affected by unevenness on the wall of the borehole, even if the unevenness is relatively large, and also aims to provide a construction method for an underground heat exchanger that can improve the efficiency of the construction and installation of the underground heat exchanger without requiring active sludge removal work using a sludge pump, as in Patent Document 1. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following means. That is, a first aspect of the underground heat exchange device of the present invention is an underground heat exchange device that uses a borehole formed by injecting drilling fluid to excavate and mix the ground, and is equipped with a bottomed, flexible, waterproof tubular bag that is arranged extending in the vertical direction within the borehole, which has a drilled soil mixture containing a hardening agent stored inside, a vertically extending buoyancy resistance material that extends in the vertical direction along the outer surface of the tubular bag within the borehole and whose lower end is connected to the lower end of the tubular bag, and a reaction material that supports the upper end of the buoyancy resistance material so that the upper end does not move upward. The cylindrical bag, whose lower end is located at the bottom of the borehole, is filled with a heat transfer liquid having a lower specific gravity than the excavated soil mixture, and the outer diameter of the cylindrical bag, which is expanded to its maximum extent by this, is set to be smaller than the inner diameter of the borehole, and the buoyancy acting on the cylindrical bag containing the heat transfer liquid present in the excavated soil mixture in the borehole is resisted by the buoyancy resistance material which is in a tensioned state between the lower end of the bag and the reaction material, thereby preventing the cylindrical bag from floating up.

[0008] A second aspect of the underground heat exchanger according to the present invention is an underground heat exchanger that uses a borehole formed by injecting drilling fluid into the ground to excavate and agitate the ground, The device comprises: a bottomed, flexible, waterproof tubular bag that is arranged extending vertically within the borehole, which stores an excavation soil mixture containing a hardening agent inside; a first water pipe that extends vertically along the outer surface of the tubular bag within the borehole, the lower end of the water pipe being connected in communication with the lower end of the tubular bag; a vertically extending buoyancy resistance material that extends vertically along the outer surface of the tubular bag within the borehole, the lower end of the resistance material being connected to the lower end of the tubular bag; and a reaction material that supports the upper end of the buoyancy resistance material to prevent the upper end from moving upward. The cylindrical bag, whose lower end is located at the bottom of the borehole, contains a heat transfer liquid having a lower specific gravity than the excavated soil mixture, and the outer diameter of the cylindrical bag, when it is fully expanded, is set to be smaller than the inner diameter of the borehole, and the buoyancy acting on the cylindrical bag containing the heat transfer liquid present in the excavated soil mixture in the borehole is resisted by the buoyancy resistance material which is in a tensioned state between the lower end of the bag and the reaction material, thereby preventing the cylindrical bag from floating up.

[0009] A third aspect of the underground heat exchange device of the present invention is characterized in that, in the first aspect, the buoyancy resistance material is configured as a steel cylindrical body extending vertically so as to accommodate the tubular bag body in the vertical direction, and the tubular bag body extending vertically is accommodated within the cylindrical body.

[0010] A fourth aspect of the underground heat exchange device of the present invention is the second aspect, characterized in that the buoyancy resistance material is configured as a steel cylindrical body extending vertically to accommodate the tubular bag body in the vertical direction, the tubular bag body extending vertically is accommodated within the cylindrical body, and the first water pipe is arranged extending vertically while accommodated within the cylindrical body, or is arranged extending vertically along the outer surface of the cylindrical body.

[0011] A fifth aspect of the underground heat exchange device of the present invention is characterized in that, in the third or fourth aspect, the steel cylindrical body is formed into a cylindrical shape by connecting axial reinforcing bars installed upright at a required angular pitch in the circumferential direction with ring reinforcing bars at a required interval above and below.

[0012] A sixth aspect of the underground heat exchange device of the present invention is characterized in that, in the third aspect, the steel cylindrical body is formed into a cylindrical shape by connecting axial reinforcing bars, which are set upright at a required angular pitch in the circumferential direction, with annular reinforcing bars at a required interval above and below, and the axial reinforcing bars are connected to the annular reinforcing bars while abutting the inner and / or outer peripheral surfaces of the annular reinforcing bars, and all of the annular reinforcing bars have introduction openings cut out on the same side when viewed from above, through which the tubular bag body can be introduced into the cylindrical body.

[0013] The seventh aspect of the underground heat exchanger of the present invention is characterized in that, in the fourth aspect, the steel cylindrical body is formed into a cylindrical shape by connecting axial reinforcing bars, which are set upright at a required angular pitch in the circumferential direction, with annular reinforcing bars at a required interval above and below, and the axial reinforcing bars are connected to the annular reinforcing bars while abutting the inner and / or outer peripheral surfaces of the annular reinforcing bars, and all of the annular reinforcing bars have introduction openings cut out on the same side when viewed from above, through which the tubular bag body and the first water pipe can be introduced into the cylindrical body.

[0014] In a first aspect of the method for constructing a geothermal heat exchanger according to the present invention, a borehole is formed by injecting drilling fluid into the ground to excavate and agitate the ground, and a soil mixture containing a hardener is stored in the borehole. A number of flexible, waterproof cylindrical bags, each having a bottom and extending in the vertical direction, are successively lowered into the borehole together with buoyancy resistance materials whose lower ends are connected to the lower ends of the bags. When the lower ends of the bags reach the bottom of the borehole, a heat transfer liquid having a specific gravity less than that of the soil mixture is supplied into the cylindrical bags, causing the cylindrical bags to expand. When the excavated soil mixture is interposed between the outer peripheral surface of the expanded cylindrical bag and the inner peripheral surface of the borehole, the buoyancy force acting on the cylindrical bag will cause the upper end of the buoyancy resistance material to tend to float up together with the cylindrical bag, but the upper end is supported by a reaction material installed at the upper end of the borehole to prevent the upper end from moving upward, and the tensioning action of the buoyancy resistance material, which is in a tensioned state between the lower end of the bag and the reaction material, prevents the cylindrical bag, which is connected to the lower end of the resistance material, from floating up.The reaction material is then no longer necessary after the fully expanded cylindrical bag is fixed in the borehole by the hardening action of the hardening agent.

[0015] In a second aspect of the method for constructing a geothermal heat exchanger according to the present invention, a borehole is formed by excavating the ground and filled with a soil mixture containing a hardening agent, and a flexible, waterproof tubular bag extending in the vertical direction and having a bottom is successively lowered into the borehole together with a first water pipe whose lower end is connected in communication with the lower end of the bag and a buoyancy resistance material whose lower end is connected to the lower end of the bag. When the lower end of the bag reaches the bottom of the borehole, a heat transfer liquid having a specific gravity lower than that of the soil mixture is supplied into the tubular bag to expand the tubular bag. When the excavated soil mixture is interposed between the outer peripheral surface of the expanded cylindrical bag and the inner peripheral surface of the borehole, the buoyancy force acting on the cylindrical bag causes the upper end of the buoyancy resistance material to tend to float up together with the cylindrical bag, but the upper end is supported by a reaction material installed at the upper end of the borehole to prevent the upper end from moving upward, and the tensioning action of the buoyancy resistance material, which is in a tensioned state between the lower end of the bag and the reaction material, prevents the cylindrical bag, which is connected to the lower end of the resistance material, from floating up. After the fully expanded cylindrical bag is fixed in the borehole by the hardening action of the hardening agent, the reaction material becomes unnecessary.

[0016] A third aspect of the construction method for a geothermal heat exchanger according to the present invention is a construction method for a geothermal heat exchanger according to the first aspect, wherein the buoyancy resistance material is configured as a steel cylindrical body extending vertically so as to accommodate the cylindrical bag body in the vertical direction, and the cylindrical body is configured in a cylindrical shape by connecting axial reinforcing bars, which are set upright at a required angular pitch in the circumferential direction, with annular reinforcing bars at required intervals vertically, and the axial reinforcing bars are connected to the annular reinforcing bars in a state of abutting the inner and / or outer peripheral surfaces of the annular reinforcing bars, and all of the annular reinforcing bars have introduction openings cut out on the same side when viewed from above so as to allow the bag body to be introduced into the cylindrical body, and the lower end of the cylindrical body, which is the lower end of the cylindrical body, is the lower end of the resistance material. As the cylindrical body is lowered into the borehole, the cylindrical bag body, whose lower end is connected to the lower end of the cylindrical body, is sequentially accommodated in the cylindrical body through the introduction opening while extending in the vertical direction.

[0017] In a fourth aspect of the method for constructing a geothermal heat exchanger according to the present invention, in the second method for constructing a geothermal heat exchanger, the buoyancy resistance material is configured as a vertically extending steel tube that can accommodate the tubular bag in the vertical direction, the tube is configured as a tube by connecting axial reinforcing bars arranged circumferentially at a required angular pitch with annular reinforcing bars at required vertical intervals, all of the annular reinforcing bars have introduction openings cut out on the same side in a plan view through which the bag can be introduced into the tube, and the lower end of the tube is the lower end of the resistance material. As the tube is lowered into the borehole, the tubular bag, formed by connecting the lower end of the bag to the lower end of the tube, and the first water pipe are sequentially inserted into the tube through the introduction openings while extending vertically.

[0018] In a fourth aspect of the method for constructing a geothermal heat exchanger according to the present invention, in the second method for constructing a geothermal heat exchanger, the buoyancy resistance material is configured as a vertically extending steel tube that can accommodate the tubular bag in the vertical direction, the tube is configured as a tube by connecting axial reinforcing bars arranged circumferentially at a required angular pitch with annular reinforcing bars at required vertical intervals, all of the annular reinforcing bars have introduction openings cut out on the same side in a plan view through which the bag can be introduced into the tube, and the lower end of the tube is the lower end of the resistance material. As the tube is lowered into the borehole, the tubular bag, formed by connecting the lower end of the bag to the lower end of the tube, and the first water pipe are sequentially inserted into the tube through the introduction openings while extending vertically.

[0019] A fifth aspect of the construction method for an underground heat exchanger according to the present invention is characterized in that, in the construction method for an underground heat exchanger of the third aspect, an escape prevention means is used to prevent the cylindrical bag body introduced into the cylindrical body from escaping from the introduction opening.

[0020] A sixth aspect of the construction method for an underground heat exchanger according to the present invention is characterized in that, in the construction method for an underground heat exchanger according to the fourth aspect, an escape prevention means is used to prevent the tubular bag body and the first water pipe introduced into the tubular body from escaping from the introduction opening. [Effects of the Invention]

[0021] The present invention has the following excellent effects. According to the present invention, an underground heat exchange device can be provided that can efficiently exchange heat with the borehole wall without being affected by unevenness on the borehole wall, even if the unevenness is relatively large.

[0022] Furthermore, the present invention provides a construction method for an underground heat exchanger that can efficiently construct an underground heat exchanger without the need for actively draining mud from the borehole using a sludge pump, as in Patent Document 1. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an explanatory diagram illustrating a geothermal heat exchange device according to the present invention. [Figure 2] 1 is a partially enlarged view of a geothermal heat exchanger according to the present invention. [Figure 3] FIG. 1 is an explanatory diagram of a construction method for the underground heat exchanger according to the present invention, which is carried out using a pile driver and a crane. [Figure 4] FIG. 2 is a perspective view showing a cylindrical body that is an example of a buoyancy resistance material. [Figure 5] FIG. 10 is a perspective view showing a cylindrical unit located at the top. [Figure 6] FIG. 10 is an explanatory view illustrating a step of connecting a first tubular unit and a second tubular unit. [Figure 7] This is an explanatory diagram showing a case where the annular reinforcing bar that constitutes the cylindrical body and the escape prevention means provided at the introduction opening of the annular reinforcing bar are constructed using a short flexible hose. [Figure 8] FIG. 10 is an explanatory view illustrating the process of introducing the cylindrical bag body and the first water pipe into the cylindrical body through the introduction opening of the ring-shaped reinforcing bar. [Figure 9] FIG. 10 is a perspective view showing a tubular bag body crushed in the width direction. [Figure 10] FIG. 10 is an explanatory diagram illustrating a case where upper and lower unit cylindrical bodies are connected to each other by connecting an upwardly protruding axial reinforcing bar and a downwardly protruding axial reinforcing bar via a connecting fitting. [Figure 11] FIG. 1 is a perspective view showing a reaction member configured as a concrete block. [Figure 12] FIG. 10 is an explanatory view illustrating a step of connecting a second tubular unit and a third tubular unit. [Figure 13]10 is a cross-sectional view showing a state in which a hardened layer formed by hardening of the excavation soil mixture liquid is formed between the outer surface of the cylindrical bag body and the hole wall surface of the borehole. FIG. [Figure 14] 1 is an explanatory diagram illustrating a geothermal energy utilization device for utilizing the heat contained in a heat transfer liquid in a cylindrical bag. [Figure 15] 10 is an explanatory diagram illustrating another embodiment of a geothermal energy utilization device for utilizing the heat contained in the heat transfer liquid in the cylindrical bag. FIG. [Figure 16] 10 is an explanatory diagram illustrating another embodiment of a geothermal energy utilization device for utilizing the heat contained in the heat transfer liquid in the cylindrical bag. FIG. [Figure 17] 10A and 10B are explanatory diagrams illustrating another aspect of the escape prevention means. [Figure 18] FIG. 10 is an explanatory diagram illustrating another embodiment of the buoyancy resistance material. [Figure 19] FIG. 10 is an explanatory diagram illustrating another embodiment of the buoyancy resistance material. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0024] 1 and 2, the geothermal heat exchange device 1 of the present invention is a geothermal heat exchange device that uses a borehole 2 formed by injecting drilling fluid into the ground to excavate and mix it, and is equipped with a bottomed, flexible, waterproof tubular bag 5 that is arranged extending vertically within the borehole 2, which stores a drilled soil mixture 3 containing a hardening agent inside, a first water pipe 10 that extends vertically along the outer surface 6 of the tubular bag 5 within the borehole 2 and has a water pipe lower end 7 connected to a bag lower end 9 of the tubular bag 5 in a communicating state, a buoyancy resistance material 12 that extends vertically along the outer surface 6 of the tubular bag 5 within the borehole 2 and has a resistance material lower end 11 connected to the bag lower end 9, and a reaction material 15 that supports an upper end 13 of the buoyancy resistance material 12 to prevent the upper end 13 from moving upward. The cylindrical bag 5, whose lower end 9 is located at the bottom 16 of the borehole 2, contains a heat transfer liquid 17 having a specific gravity lower than that of the excavated soil mixture 3, and the outer diameter of the cylindrical bag 5, which is maximally expanded, is set to be smaller than the inner diameter of the borehole 2. The buoyancy acting on the cylindrical bag 5 containing the heat transfer liquid 17 present in the excavated soil mixture 3 in the borehole 2 is resisted by the buoyancy resistance material 12 which is in a tensioned state between the bag lower end 9 and the reaction material 15, thereby preventing the cylindrical bag 5 from floating up. The reaction material 15 becomes unnecessary after the excavated soil mixture 3 hardens.

[0025] The borehole 2 is drilled to a required depth by injecting drilling fluid using a pile driver. In this embodiment, the borehole 2 has an inner diameter of about 500 mm and a depth of about 30 m. The drilling fluid is made of water and bentonite.

[0026] The excavated soil mixture 3 is a mixture of soil and sand produced by the excavation and hardening materials, etc., and the hardening materials are cement mixtures such as cement milk, mortar, concrete, blast furnace slag, resins such as epoxy resin, water glass, etc.

[0027] The tubular bag 5 has a bottom, is a flexible, tubular, waterproof woven bag body, and has a reinforcing resin, such as polyurethane resin, applied to the inside of the tubular bag 5, so that the tubular bag 5 can resist soil pressure when the heat transfer liquid 17 is stored inside the tubular bag 5. The tubular bag 5 can expand when the heat transfer liquid 17 is stored inside. The outer diameter of the maximally expanded tubular bag 5 (hereinafter, the expanded tubular bag 5 is also referred to as tubular bag 5a) is set to be smaller than the inner diameter of the borehole 2, and in this embodiment, the outer diameter is set to be about 300 mm.

[0028] The specific gravity of the heat transfer liquid 17 contained in the cylindrical bag 5 is smaller than that of the excavated soil mixture liquid (specific gravity 1.1 to 2.0) 3. The heat transfer liquid 17 is a medium for transporting thermal energy, and is usually water. In cold regions, antifreeze liquid itself may be used as the heat transfer liquid, or water mixed with antifreeze liquid may be used as the heat transfer liquid.

[0029] In this embodiment, the first water pipe 10 is made of a polyethylene pipe, extends vertically along the outer surface 6 of the tubular bag 5a, and has a lower end 7 of the water pipe connected to a lower end 9 of the bag via a connecting pipe 19 (e.g., a U-shaped connecting pipe 19a) in a communicating state. The first water pipe 10 supplies the heat transfer liquid 17 into the tubular bag 5 at its lower end 20, or sucks the heat transfer liquid 17 into the tubular bag 5 at its lower end.

[0030] The buoyancy-resistant material 12 has a structure capable of resisting the buoyancy acting on the tubular bag 5a containing the heat transfer liquid 17 present in the excavated soil mixture 3 in the borehole 2, thereby preventing the tubular bag 5a from floating up. In this embodiment, the buoyancy-resistant material 12 is configured as a vertically extending steel cylindrical body 21 as shown in Figures 3 to 6, and the vertically extending tubular bag 5 is contained in a storage section 22 within the cylindrical body 21. In this embodiment, when the tubular bag 5 is contained in the storage section 22, the vertically extending buoyancy-resistant material 12 extends vertically along the outer surface of the tubular bag 5 within the borehole 2.

[0031] In this embodiment, the outer diameter of the cylindrical body 21 is set to approximately 350 mm. As shown in Figures 4 and 6, the cylindrical body 21 is configured by connecting axial reinforcing bars 23, which are installed upright at a required angular interval (e.g., 120° angular interval) in the circumferential direction, with horizontally arranged ring-shaped reinforcing bars 25 at required intervals (e.g., 300 to 1000 mm intervals, 500 mm intervals in this embodiment) to achieve a highly rigid cylindrical shape with excellent buckling resistance, capable of exerting the required tensioning action described below. The axial reinforcing bars 23 are connected to the ring-shaped reinforcing bars 25 in abutting relation to the inner peripheral edge 25A and / or outer peripheral edge 25B of the ring-shaped reinforcing bars 25. In this embodiment, all of the axial reinforcing bars 23 are connected to the inner peripheral edge 25A. Furthermore, in this embodiment, the upper and lower end ring-shaped reinforcing bars 25a, 25b are positioned approximately 1 m inward from the upper and lower ends 26, 27 of the axial reinforcing bars 23.

[0032] In this embodiment, all of the annular reinforcing bars 25 are configured as C-shaped rings 30 having an overall C-shape, with introduction openings 29 cut out to allow the tubular bag body 5 and the first water pipe 10 to be introduced into the tubular body 21 (FIG. 4), as shown in FIGS. 4, 7(A), and 8. In this embodiment, the introduction openings 29 of the tubular body 21 are arranged vertically in a straight line on the same side in a plan view, as shown in FIG. 4. The tubular bag bodies 5 introduced into the tubular body 21 (FIG. 4) through the introduction openings 29 are crushed in the width direction, as shown in FIGS. 8 and 9. FIG. 9 is a perspective view showing the tubular bag body 5 in a widthwise crushed state. In this embodiment, the diameter of the axial reinforcing bar 23 is set to approximately 19 mm, and the diameter of the annular reinforcing bar 25 is set to approximately 13 mm. The width (opening) of the introduction openings 29 of the annular reinforcing bar 25 is set to approximately 150 mm.

[0033] The tubular bag 5 and the first water pipe 10 introduced into the tubular body 21 through the introduction opening 29 may escape from the introduction opening 29. Therefore, in this embodiment, the introduction opening 29 is equipped with an escape prevention means 31 for preventing these from escaping. In this embodiment, as shown in FIG. 7(B), the escape prevention means 31 is composed of left and right short-length flexible hoses 32 (e.g., 250 to 300 mm long). The base end portions 33 of each short-length flexible hose 32 are attached to the end portions 34 of the C-shaped ring 30. This attachment is achieved by press-fitting the end portions 34 into the base end portion 33. As shown in FIG. 7(B), by overlapping the middle portions 36 of the pair of short-length flexible hoses 32 and connecting them with a cable tie 37, the introduction opening 29 (FIG. 7(A)) can be closed to prevent the escaping. The flexible hoses 32, 32 also have the function of preventing the C-shaped ends 35, 35 from damaging the tubular bag body 5.

[0034] In this embodiment, the total length of the cylindrical body 21 (FIG. 3) is set to about 30 m. In this embodiment, the cylindrical body 21 is configured by connecting unit cylindrical bodies 39, 39, each having a total length of about 10 m, at their upper and lower end portions 40, 40, as will be described later, as shown in FIG.

[0035] In the following description, the three unit cylindrical bodies 39, 39, 39 will be appropriately distinguished as unit cylindrical body 39A, unit cylindrical body 39B, and unit cylindrical body 39C.

[0036] Of the three unit cylindrical bodies 39, 39, 39 having this configuration, the uppermost unit cylindrical body 39C has an abutting flat plate (made of iron plate) 42 fixed to its upper end 41, covering the upper end 41, as shown in Fig. 5. Also as shown in the same figure, a water-pipe-fixing flat plate 50 is fixed to the uppermost unit cylindrical body 39C, for example, about 1.5 m below the abutting flat plate 42. As shown in Fig. 2, the water-pipe-fixing flat plate 50 abuts against the upper end portion of the tubular bag body 5a expanded in the borehole 2 as described below (in this embodiment, the upper end portion 47 of the connecting member 46 of the second water pipe 45 connected to the upper end 43 of the expanded tubular bag body 5a), thereby fixing the base end 49 of the second water pipe 45 in a required position. 5, the water-pipe fixing plate 50 is provided with a notch 51 for guiding the second water pipe 45 and the first water pipe 10 upward, and the inner end of the notch 51 serves as an insertion section 52 for guiding the second water pipe 45 upward. The abutting plate 42 also has an insertion notch 53 for guiding the first and second water pipes 10, 45 upward.

[0037] As described above, the flat plate 50 for fixing the water pipe is provided in order to regulate the upper end position of the tubular bag 5 and prevent interference between the tubular bag 5 and pipes of structures, etc., which are often buried at a depth of 1 to 1.5 m below the ground surface 55 (Figure 6).

[0038] The reaction member 15 (Fig. 1), as shown in Fig. 11, is configured as a rectangular concrete block 15a (weighing, for example, 2 tons in this embodiment) that is square in plan view and has a notched opening 56 for guiding the first water pipe 10 and the second water pipe 45 upward. The rectangular concrete block 15a is placed on the ground surface 55 with the notched opening 56 aligned with the insertion notch 53 (Fig. 5) so that its flat lower surface 57 (Figs. 1 and 11) can abut against the upper surface 54 of the abutting plate body 42 (the upper end 13 of the buoyancy-resisting material 12 shown in Fig. 5), thereby resisting the buoyancy acting on the inflated cylindrical bag body 5a.

[0039] Next, a construction method for the heat exchanger will be described with reference to FIGS. 1 to 3, 10, etc. However, in FIG. 10, the cylindrical bag 5a is not shown. In this construction method, a borehole 2 is formed by excavating the ground with a pile driver 59 (FIG. 3), and the excavated soil mixture 3 containing the hardening agent is stored in the borehole. A bottomed, flexible, waterproof cylindrical bag 5 extending vertically and having a bottom is then lowered into the borehole 2 together with a first water pipe 10 having a water pipe lower end 7 connected to the bag lower end 9, and the cylindrical body 21 (the buoyancy resistance material 12) having a cylindrical body lower end 60 (the resistance material lower end 11) connected to the bag lower end 9 (FIG. 3). The connection state between the bag lower end 9 and the water pipe lower end 7 and the connection state between the bag lower end 9 and the cylindrical body lower end 60 are shown in FIG. 2. When the bag lower end 9 has reached the bottom 16 of the borehole 2, a heat transfer liquid 17 is supplied into the cylindrical bag 5 to expand the cylindrical bag 5. With the excavated soil mixture 3 interposed between the outer peripheral surface 61 of the expanded cylindrical bag 5a and the hole wall surface (inner peripheral surface) 62 of the borehole 2, the buoyancy acting on the expanded cylindrical bag 5a causes the upper end 13 of the buoyancy resistance material 12 to tend to float up together with the cylindrical bag 5a. To prevent the upper end 13 from moving upward, the buoyancy resistance material 12 is supported by a reaction material 15 installed at the upper end 63 of the borehole 2, as shown in Figures 1 and 10. As a result, the tensioning action of the buoyancy resistance material 12, which is in a tensioned state between the bag lower end 9 and the reaction material 15, prevents the tubular bag 5a, which is formed by connecting the bag lower end 9 to the resistance material lower end 11, from floating up (Figs. 1-2, 10(A)). After the tubular bag 5a, which has expanded to its maximum extent, is fixed in the borehole 2 as the excavation soil mixture 3 hardens, the reaction material 15 becomes unnecessary. This will be described in detail below in the order of steps.

[0040] FIG. 3 shows the state in which the cylindrical body 21 (the buoyancy resistance material 12) is suspended by a crane 65, and the state in which the cylindrical bag body 5 is suspended by the pile driver 59. As shown in FIG. 9, the cylindrical bag body 5 in the suspended state is extended in the vertical direction while being collapsed in the width direction. FIG. 2 shows the state in which the bag body lower end portion 9 has reached the bottom 16 of the borehole 2, and also shows the state in which the water pipe lower end portion 7 of the first water pipe 10 is connected to the bag body lower end portion 9 via the U-shaped connecting pipe 19a, and the resistance material lower end portion 11 is connected to the U-shaped connecting pipe 19a via a shackle 66, thereby connecting the resistance material lower end portion 11 to the bag body lower end portion 9. In this embodiment, this connected state is a state in which the resistance material lower end portion 11 is slightly separated from the bag body lower end portion 9.

[0041] The connection between the resistance material lower end 11 and the bag lower end 9 via the shackle 66 is made on the ground. That is, the connection is made with the resistance material lower end 11 of the suspended unit cylindrical body 39A (unit cylindrical body 39 that will be located at the lowest end in the borehole 2) positioned slightly above the upper end of the borehole 2 in which the excavated soil mixture 3 containing the hardening agent is stored, and with the bag lower end 9 positioned at approximately the same height as the resistance material lower end 11.

[0042] With the resistance material lower end 11 and the bag body lower end 99 connected in this manner, the tubular unit 39A is hung down and inserted sequentially into the borehole 2. At the same time, the tubular bag body 5 is hung down at the same speed as the tubular body 21 is hung down (FIG. 3).

[0043] At this time, the worker pushes the tubular bag 5 (FIG. 9) and the first water pipe 10, which are successively being lowered and collapsed in the width direction, into the tubular body 39A (the storage section 22) through the introduction opening 29 as shown by the arrow in FIG. 8. In this embodiment, the pushing is performed through the opening 29a between the bent portions 67, 67, which is formed by folding each of the short flexible hoses 32, 32 in half at the bent portion 67 and binding them with a detachable band 37. Note that the connection of the intermediate portions 36, 36 to each other with the binding band 37, as shown in FIG. 7(B), is performed after the binding with the detachable band 37 is released.

[0044] When using the horizontal insertion method performed through such an introduction opening 29a, the insertion work of inserting the tubular bag body 5 and the first water pipe 10 into the unit tubular body 39A can be performed easily and efficiently while hanging down the tubular body 21 and the tubular bag body 5.

[0045] Thereafter, as shown in Figure 7(B), the middle portions 36, 36 of the pair of short flexible hoses 32, 32 constituting the escape prevention means 31 are overlapped and connected with the binding band 37, thereby preventing the tubular bag body 5 and the first water conduit 10 introduced into the unit tubular body 39A (Figure 4) from escaping through the introduction opening 29. Note that the tubular bag body 5 and the first water conduit 10 are not shown in Figure 7(B).

[0046] When the tubular unit 39A is lowered in the borehole 2, the tubular bag 5 also sinks because the bag lower end 9 is connected to the tubular lower end 60 (which constitutes the resistance material lower end 11) (FIG. 3). During this lowering process, the pushing operation and the escape prevention operation are performed. The lowering is continued until the upper end 68A of the tubular unit 39A protrudes approximately 100 cm from the upper end 63 of the borehole 2, as shown in FIG. 6. After this lowering, both end portions 64, 64 of a support bar (e.g., a single pipe) 69 supporting the uppermost annular reinforcing bar 25A of the tubular unit 39A from below are placed on supports 70, 70 installed around the upper end of the borehole 2, so that the tubular unit 39A is supported in a suspended state, as shown by the dashed line in FIG. 4.

[0047] With the tubular unit 39A supported in this manner, the second tubular unit 39B is lowered by the crane 65, as indicated by arrow F1 in FIG. 6. As shown in FIG. 10(B), the upwardly protruding axial reinforcing bar 71a located at the upper end of the lower tubular unit 39A is overlapped with the downwardly protruding axial reinforcing bar 71b located at the lower end of the upper tubular unit 39B, with their axes aligned. The overlapping distance is determined as required depending on the diameter of the axial reinforcing bars, and is set to approximately 860 mm in this embodiment. The overlapping upwardly protruding axial reinforcing bar 71a and downwardly protruding axial reinforcing bar 71b are then connected at their upper, lower, and intermediate positions with bolts and nuts via connecting fittings (not shown). In FIG. 10(B), the connecting portions are indicated by horizontal dashed lines 74. This connects the first tubular unit 39A and the second tubular unit 39B.

[0048] 12, the second-stage tubular unit 39B is lowered into the borehole 2 while the pushing operation and the escape prevention operation are being carried out in the same manner as in the first-stage tubular unit 39A, and the lowering of the second-stage tubular unit 39B continues until its upper end portion 68B protrudes about 100 cm from the upper end 63 of the borehole. After the second-stage tubular unit 39B has been lowered in this manner, both end portions of the support bar (e.g., a single pipe) supporting the uppermost annular reinforcing bar 25b of the second-stage tubular unit 39B are placed on the support stands 70, 70, and the second-stage tubular unit 39B is supported in a suspended state, in the same manner as in the first-stage tubular unit 39A.

[0049] With the second-tier tubular unit 39B supported in this manner, the third-tier tubular unit 39C is lowered by a crane, as shown by arrow F2 in Figure 12. As shown in Figure 10(B), the upward-protruding axial reinforcing bar 71c located at the upper end of the second-tier tubular unit 39B is overlapped with the downward-protruding axial reinforcing bar 71d located at the lower end of the third-tier tubular unit 39C, with their axes aligned. In this embodiment, the overlapping distance is set to approximately 860 mm. Then, in the same manner as described above, the upward-protruding axial reinforcing bar 71c and the downward-protruding axial reinforcing bar 71d are connected at their upper, lower, and intermediate positions with bolts and nuts via connecting fittings (not shown).

[0050] Thereafter, the third-stage tubular unit 39C is lowered into the borehole 2 while performing the pushing operation (FIG. 8) and the escape prevention operation (FIG. 7(B)) in the same manner as for the first-stage tubular unit 39A. With the upper end 43 of the third-stage tubular unit 39C protruding about 150 cm from the upper end 63 of the borehole 2, the lower end of the second water pipe 45 is connected to the upper end 43 of the tubular bag body 5 via the connecting member 46.

[0051] 12, the third tubular unit 39C is lowered and the abutting plate 42 (FIG. 5) fixed to the upper end of the tubular unit 39C is positioned at the upper end portion of the borehole 2. In this state, as shown in FIG. 2, the bag lower end 9 has reached the bottom 16 of the borehole 2, and the resistance material lower end 11 of the buoyancy resistance material 12 is connected to the lower end 9 (the bag lower end) of the lowest tubular unit 39A via the U-shaped connecting pipe 19a.

[0052] In Figure 10(A), the part indicated by the symbol L1 is the connection between the upwardly protruding rebar 71a and the downwardly protruding rebar 71b, and the part indicated by the symbol L2 is the connection between the upwardly protruding rebar 71c and the downwardly protruding rebar 71d.

[0053] In this connected state, as shown in Figures 1 and 10(A), the reaction material 15 (in this embodiment, the rectangular concrete block 15a) is installed so as to cover the upper end of the borehole 2, and then the heat transfer liquid 17 as water is supplied into the cylindrical bag body 5 through the first water pipe 10 to form the expanded cylindrical bag body 5a.

[0054] The excavated soil mixture 3 is interposed between the outer peripheral surface 61 of the expanded cylindrical bag 5a and the inner peripheral surface 62 of the borehole 2. Because the specific gravity of the heat transfer liquid 17 is smaller than that of the excavated soil mixture 3 and because the lower end portion 11 of the resistance material is connected to the lower end portion 9 of the bag, the buoyancy acting on the cylindrical bag 5a causes the cylindrical body 21 to rise together with the cylindrical bag 5a.

[0055] As shown in Figure 10(A), the abutting flat plate 42 (Figure 5) provided at the upper end of the floated cylindrical body 21 abuts against the underside 57 of the reaction material 15 (in this embodiment, the underside of the rectangular concrete block 15a), and the upper end 13 of the buoyancy resistance material 12 is supported by the rectangular concrete block 15a so as not to move upward.As a result, the tensioning action of the buoyancy resistance material 12, which is in a tensioned state between the bag lower end 9 and the reaction material 15, prevents the tubular bag 5a, which is formed by connecting the bag lower end 9 to the resistance material lower end 11, from floating up (Figures 1 and 10(A)).

[0056] After the excavated soil mixture 3 has hardened due to the hardening action of the hardener, the buoyancy of the cylindrical bag 5a is no longer generated, and the reaction material 15 is no longer necessary. The reaction material 15 that is no longer necessary may be removed, but may be left in place if it does not interfere with the structure. The upper end portion of the third-stage unit cylindrical body 39C located above the upper end 43 of the cylindrical bag 5a (the portion of the unit cylindrical body 39C shown in Figure 5 that is above the water pipe fixing flat body 50) may be cut off if it interferes with the structure.

[0057] The hardened material 72 formed by the hardening of the excavation soil mixture 3 in this manner is in close contact with the hole wall surface 62 of the borehole 2, as shown in Figure 13 (where the hole wall surface 62 is uneven, the hardened material 72 is in close contact with the unevenness, stabilizing the hole wall surface 62 and preventing the hole wall from collapsing), and the hardened material 72 is in close contact with the outer surface 61 of the tubular bag body 5a, and in this embodiment, a hardened material layer 73 about 100 mm thick is interposed around the tubular bag body 5a (Figure 13).

[0058] Therefore, the entire outer peripheral surface 61 of the tubular bag 5a is in close contact with the hole wall 62 of the borehole 2 via the hardened material 72. The thermal conductivity of the hardened material 72 is equal to or greater than that of the ground. Therefore, even if the hole wall 62 of the borehole 2 has irregularities and the irregularities are relatively large, efficient heat exchange can be achieved between the hole wall 74 and the heat transfer liquid 17 in the tubular bag 5 without any heat insulating portion being affected by the irregularities. In the present invention, the irregularities mean a non-planar shape having recesses and / or protrusions.

[0059] Furthermore, when using the construction method for an underground heat exchanger having the above-mentioned configuration, the underground heat exchanger can be constructed efficiently without the need for actively draining mud from the borehole using a sludge pump, as in Patent Document 1.

[0060] 14 shows an example of a geothermal energy utilization device for utilizing the heat contained in the heat transfer liquid 17 stored in the cylindrical bag 5a. In the figure, the upper end 75 of the first water pipe 10 and the upper end 76 of the second water pipe 45 are connected via connecting pipes 82 and 83 to one pipe section 80 and the other pipe section 81 of a heat absorption / radiation pipe section 79 that can absorb heat in a heat absorption / radiation region 77, respectively, thereby forming a pipeline 85 through which the heat transfer liquid 17 flows. A pump 86 for circulating the heat transfer liquid 17 within the pipeline 85 is disposed at a required position of the connecting pipes 82 and 83, and a switching valve (not shown) for switching the operation of the geothermal heat exchange device 1 between summer and winter is also provided in the pipeline 85. Examples of the heat absorption and dissipation areas include the interiors of various buildings such as buildings, houses, factories, warehouses, and livestock barns, the surfaces of paved areas such as parking lots, public roads, and bridges, and the surfaces of paved areas around railway stations and tunnels, and various other areas that require heat absorption and dissipation. [Example]

[0061] The present invention is by no means limited to the above-described embodiments, and it goes without saying that various design modifications are possible within the scope of the claims. Examples of such modifications are as follows.

[0062] (1) Figure 15 shows a case where both the first water pipe 10 and the second water pipe 45 are installed inside the tubular bag 5a storing the heat transfer liquid 17, and a lower end 87 of the first water pipe 10 is inserted up to a bottom 89 of the tubular bag 5a. A lower end 90 of the second water pipe 45 is located at an upper end 91 inside the tubular bag 5a. This is an embodiment in which the first water pipe 10 extending vertically along the outer surface 6 of the tubular bag 5 inside the borehole 2 is not provided. 14, the upper end 75 of the first water pipe 10 and the upper end 76 of the second water pipe 45 are connected via the connecting pipes 82, 83 to one pipe section 80 and the other pipe section 81 of the heat absorption and radiation pipe section 79, which can absorb and radiate heat in the heat absorption and radiation area 77, thereby forming the pipe line 85 through which the heat transfer liquid 17 flows, and by providing the pipe line 85 with a pump 86 and a switching valve, the heat within the tubular bag body 5a can be utilized for various purposes in the heat absorption and radiation area 77.

[0063] (2) In Fig. 16, a U-shaped pipe 84 is housed inside the cylindrical bag 5a in which the heat transfer liquid 17 is stored, and one end 84a and the other end 84b of the U-shaped pipe 84 are connected to one pipe section 80 and the other pipe section 81 of the heat absorption and radiation pipe section 79 via connecting pipe sections 82 and 83, respectively, as in the case of Fig. 14. This forms the pipe line 85 through which a fluid heat transfer medium (liquid or gas) 88 flows. By operating a pump 86 disposed at a required location of the pipe line 85, the fluid heat transfer medium 88 is circulated inside the pipe line 85, and the heat absorbed and radiated by the U-shaped pipe 84 can be supplied to the heat absorption and radiation region 77.

[0064] (3) When the buoyancy resistance material 12 is configured as the cylindrical body 21 having the above-described configuration, the diameter of the annular reinforcing bar 25 is set as required according to the diameter of the borehole 2. If the diameter of the borehole 2 is larger, the diameter of the annular reinforcing bar 25 also becomes larger accordingly. If the diameter of the annular reinforcing bar 25 becomes larger, the number of axial reinforcing bars 23 constituting the cylindrical body 21 also becomes larger. For example, the diameter of the borehole is set to 300 to 1000 mm, and the diameter of the cylindrical body 21 is set to 200 to 900 mm. The number of the axial reinforcing bars 23 is set according to the diameter of the cylindrical body 21, and may be set to 4 to 8, which is more than the above-mentioned 3, so that the cylindrical body 21 can exert the required buoyancy resistance. The axial reinforcing bar 23 may be arranged on the inner peripheral edge portion 25A (Figure 7) of the annular reinforcing bar 25 as shown in the above example, or may be arranged on the outer peripheral edge portion 25B (Figure 7) of the annular reinforcing bar 25, and the axial reinforcing bar 23 may also be arranged separately on the inner peripheral surface portion 25A and the outer peripheral surface portion 25B of the annular reinforcing bar 23. The annular reinforcing bars 25 may be arranged inside (as in the above embodiment) or outside the axial reinforcing bars 23 erected at a required angular pitch in the circumferential direction. The annular shape of the annular reinforcing bar 25 is not limited to the circular ring shape described above, and may be an annular shape other than a circular ring shape, such as a square ring shape or a pentagonal ring shape. The annular reinforcing bar 25 may not be provided with the introduction opening 29. When the annular reinforcing bar 29 is not provided with the introduction opening 29, the tubular bag body 5 and the first water pipe 10 are inserted into the tubular body 21 successively from their ends.

[0065] (4) The escape prevention means 31 for preventing the tubular bag body 5 and the first water pipe 10 introduced into the tubular body 21 from escaping through the introduction openings 29 of the annular reinforcing bar 25 can also be configured by providing the introduction openings 29 between adjacent axial reinforcing bars 23, 23 in a staggered arrangement on the left and right sides of the axial reinforcing bars 23, 23, as shown in Fig. 17. In Fig. 17, the introduction openings 29 are dotted to clarify the arrangement of the introduction openings 29.

[0066] (5) The depth and diameter of the borehole are set as required depending on the amount of heat required for the underground heat exchanger 1. The depth may be set to about 5 to 10 m.

[0067] (6) The reaction material 15 may be composed of the above-mentioned concrete blocks or various weights, or may be, for example, a self-propelled heavy machine such as a backhoe that rests on a steel plate installed to cover the upper end of the borehole 2.

[0068] (7) The buoyancy resisting materials 12 may be of the types shown in the cross-sectional views of Figures 18(A) to 18(K) and 19(A) to 19(H), as long as they can resist the buoyancy acting on the cylindrical bag 5 containing the heat transfer liquid 17 by being tensioned between the bag lower end 9 and the reaction member 15. In each type of buoyancy resisting material 12, the resistance material lower end 11 is configured by attaching an appropriate connecting member (not shown) to the lower end, and is connected to the bag lower end 9 via the connecting member. In addition, if the area of ​​the upper end of each buoyancy resisting material 12 is small, an abutment plate member made of a steel plate or the like is provided at the upper end to increase the abutment area with the reaction member 15. Furthermore, in each type of buoyancy-resistant material 12, if necessary, an introduction opening similar to that shown in Example 1 is provided for introducing the tubular bag 5 or the first water pipe 10 laterally into the storage section 22 described below. If necessary, the introduction opening 29 is configured to include escape prevention means for preventing the tubular bag 5 or the first water pipe 10 from escaping from the introduction opening 29. In each of Figures 18(A) to 18(K) and 19(A) to 19(H), the parts indicated by circles are the tubular bag 5, and the parts indicated by thick dashed lines are connecting materials 92. The buoyancy resistance material 12 shown in Figure 18(A) is constructed by arranging equal-leg angle irons extending in the vertical direction at diagonal positions with their inside corners facing each other, and connecting adjacent sides of both equal-leg angle irons at required intervals in the vertical direction (for example, intervals of 300 to 1000 mm, for example, intervals of 500 mm) with connecting materials 92 such as iron pieces. The tubular bag body 5 and the first water pipe 10 (hereinafter referred to as the tubular bag body 5) are placed in the storage section 22 between the opposing equal-leg angle irons. The buoyancy resisting material 12 shown in FIG. 18(B) is the buoyancy resisting material 12 shown in FIG. 18(A) except that the equal-leg angle irons are arranged at the four corners. The buoyancy resisting material 12 shown in FIG. 18(C) is the buoyancy resisting material 12 shown in FIG. 18(A) except that the equal angle irons are replaced with unequal angle irons. The buoyancy resistance material 12 shown in Figure 18 (D) is made up of an H-shaped steel beam extending in the vertical direction, and the tubular bag body 5 is arranged in one of its recessed portions (the storage recess 22) extending in the vertical direction. The buoyancy resistance material 12 shown in Figure 18(E) is constructed by vertically extending H-shaped steel beams facing each other with one recessed portion spaced apart at a required interval, and the opposing flanges of the opposing H-shaped steel beams are connected to each other at a required interval (for example, 1 m intervals) in the vertical direction with connecting materials 92 such as iron pieces. The tubular bag body 5 is arranged extending in the vertical direction in the storage section 22 between the opposing recessed portions. The buoyancy-resistant material 12 shown in Figure 18(F) is configured by arranging another H-shaped steel extending in the vertical direction instead of one of the left and right connecting members 99, 99 in the buoyancy-resistant material 12 shown in Figure 18(E), and connecting the flanges of the H-shaped steel and the adjacent H-shaped steel with connecting members 92. The tubular bag body 5 is arranged extending in the vertical direction in the storage section 22 formed by the three H-shaped steels. The buoyancy resistance material 12 shown in Figure 18(G) is constructed by vertically extending I-beams facing each other with one recessed portion spaced apart at a required interval, and by connecting the opposing flanges of the opposing I-beams at a required interval (for example, 1 m intervals) in the vertical direction with connecting materials 92 such as iron pieces. The tubular bag 5 is arranged extending in the vertical direction in the storage section 22 between the opposing recessed portions. The buoyancy-resistant material 12 shown in Figure 18(H) is configured by replacing one of the left and right connecting members 92, 92 of the buoyancy-resistant material 12 shown in Figure 18(G) with another I-beam extending in the vertical direction, and connecting the flanges of the I-beam and the adjacent I-beam. The tubular bag 5 is placed extending in the vertical direction in the storage section 22 formed by the three I-beams. The buoyancy resistance material 12 shown in Figure 18(I) is constructed by vertically extending channel steels with their recessed portions facing each other at a required interval, and by connecting the opposing flanges of the facing channel steels with connecting members 92 such as iron pieces at a required interval (for example, 1 m interval) in the vertical direction. The tubular bag body 5 is arranged extending in the vertical direction in the storage section 22 between the opposing recessed portions. The buoyancy resistance material 12 shown in Figure 18(J) is made up of a channel steel that extends in the vertical direction, and the tubular bag body 5 is placed in the storage section 22, which is the recessed portion of the channel steel, extending in the vertical direction. The buoyancy resistance material 12 shown in Figure 18(K) is configured by replacing one of the left and right connecting members 92, 92 of the buoyancy resistance material 12 shown in Figure 18(I) with another channel steel extending in the vertical direction, arranged with its recessed portion facing inward, and connecting the flanges of the channel steel and the adjacent channel steel to each other. The tubular bag body 5 is arranged extending in the vertical direction in the storage section 22 formed by the three channel steels. The buoyancy resistance material 12 shown in Figure 19(A) is configured as a U-shaped box-like body that is square in plan view and extends in the vertical direction, and is configured by connecting both ends of its open end with a connecting material 92 such as an iron piece. In the same figure, the U-shaped box-like body is configured by welding the ends of three flat steel pieces of equal width to each other. The tubular bag body 5 is placed in the storage section 22 of the U-shaped box-like body, extending in the vertical direction. The buoyancy resisting material 12 shown in Figure 19(B) is configured by providing flat steel protruding pieces in opposing directions on the upper ends of the opposing side pieces of the buoyancy resisting material 12 shown in Figure 19(A), and connecting the tips of the opposing flat steel protruding pieces with connecting material 92 such as an iron piece. The cylindrical bag body 5 is arranged extending in the vertical direction in the storage section 22 of the U-shaped box body. The buoyancy resistance material 12 shown in Figure 19(C) is a type in which the left and right angle portions consisting of the side pieces and the flat steel protruding pieces of the buoyancy resistance material 12 shown in Figure 19(A) have both been changed to angle irons. The buoyancy resistance material 12 shown in Figure 19(D) is a type in which one of the left and right angle portions consisting of the side pieces and the flat steel protruding pieces in the buoyancy resistance material 12 shown in Figure 19(B) is changed to one in which the flat steel protruding piece protrudes in a state where it is bent at a right angle at the tip of the flat steel. The buoyancy resistance material 12 shown in Figure 19(E) is constructed by arranging vertically extending channel steels facing each other, and connecting the flanges facing each other on one side of both channel steels with flat steel on their outer surfaces, and connecting the tips of the flanges facing each other on the other side with connecting material 92 such as iron pieces. The cylindrical bag body 5 is arranged extending vertically in the storage section 22 of the box-shaped body constructed in this way. The buoyancy resisting material 12 shown in FIG. 19(F) is a type in which one of the channel steels in the buoyancy resisting material 12 shown in FIG. 19(E) is changed to a flat steel. The buoyancy resistance material 12 shown in Figure 19(G) is constructed by arranging I-beams extending in the vertical direction facing each other, connecting the flanges facing each other on one side of both I-beams with flat steel on their outer surfaces, and connecting the flanges facing each other on the other side with connecting material 92 such as iron pieces, and the tubular bag body 5 is arranged extending in the vertical direction in the storage section 22 between the opposing recessed portions. The buoyancy resistance material 12 shown in Figure 19(H) is constructed by arranging an I-beam extending in the vertical direction and a flat steel bar extending in the vertical direction facing each other with a required distance between them, and connecting the flange of the I-beam and one edge of the flat steel bar on one side with a connecting material 92 such as an iron piece. The tubular bag body 5 is arranged in a storage section 22 between the I-beam and the flat steel bar, extending in the vertical direction.

[0069] (8) The material of the buoyancy resistance material 12 is not limited to steel as long as it can exert the required buoyancy resistance effect, and may be, for example, a composite material of steel and other materials (concrete, mortar, resin, wood, bamboo, etc.).

[0070] (9) The cylindrical bag body 5 has the lower end portion 9 of the bag body connected to the lower end portion 11 of the resistance material, but if necessary, the middle portion in the vertical direction may be connected to the buoyancy resistance material 12.

[0071] (10) The first water pipe 10 may be disposed on the inner surface side of the cylindrical body 21, or may be disposed on the outer surface side. The first water pipe 10 is appropriately fixed to the axial reinforcing bar 23 or the annular reinforcing bar 25 of the cylindrical body 21 with a binding material.

[0072] (11) The connection between the lower end 9 of the bag body and the lower end 7 of the water pipe can be carried out using the U-shaped connecting pipe 19a described above, or any other suitable connecting means that connects the lower end 9 of the bag body and the lower end 7 of the water pipe in a communicating state.

[0073] (12) The connection between the lower end portion 9 of the bag body and the lower end portion 11 of the resistance material may be a direct connection (connection in which the lower end portion 11 of the resistance material is in contact with the lower end portion 9 of the bag body) made through a known fastening means such as a connection via the shackle, or may be an indirect connection (connection in which the lower end portion 11 of the resistance material is slightly separated from the lower end portion 9 of the bag body).

[0074] (13) The escape prevention means can also be constructed using known means such as a string-like member or a sliding member that can slide circumferentially around the C-shaped ring body 30, as long as it is configured to connect the end portions 34, 34 of the C-shape to each other and prevent the tubular bag body 5 and the first water pipe 10 introduced into the tubular body from escaping from the introduction opening 29.

[0075] (14) The water pipe fixing plate body 50 may not be provided. [Explanation of symbols]

[0076] 1 Underground heat exchange equipment 2. Borehole 3 Excavation soil mixture 5. Cylindrical bag 6 External surface 7 Lower end of water pipe 9 Lower end of bag 10 First Water Pipe 11 Lower end of resistor material 12 Buoyancy resistance material 15 Reaction material 17 Heat transfer fluid 22 Storage section 23 Axial reinforcing bars 25 Circular reinforcing bars 29 Introduction opening 31 Escape prevention measures 39 Unit cylindrical body 42 Contact flat plate bag 45 Second Water Pipe 50 Flat plate for fixing water pipes 51 Notch 62 Hole wall 72 Cured product 73 Cured material layer

Claims

1. A geothermal heat exchanger using a borehole formed by injecting drilling fluid into the ground and excavating and stirring the ground, The borehole is filled with a soil mixture containing a hardening agent and is arranged to extend vertically within the borehole. The borehole is provided with a bottomed, flexible, waterproof tubular bag, a vertically extending buoyancy resistance material that extends vertically along the outer surface of the tubular bag within the borehole and has a lower end connected to the lower end of the tubular bag, and a reaction material that supports the upper end of the buoyancy resistance material so that the upper end does not move upward. A geothermal heat exchange device characterized in that the cylindrical bag, whose lower end is located at the bottom of the borehole, is filled with a heat transfer liquid having a lower specific gravity than the excavated soil mixture, and the outer diameter of the cylindrical bag, which is expanded to its maximum by this, is set to be smaller than the inner diameter of the borehole, and the buoyancy acting on the cylindrical bag containing the heat transfer liquid present in the excavated soil mixture in the borehole is resisted by the buoyancy resistance material, which is in a tensioned state between the lower end of the bag and the reaction material, thereby preventing the cylindrical bag from floating up.

2. A geothermal heat exchanger using a borehole formed by injecting drilling fluid into the ground and excavating and stirring the ground, The borehole comprises a bottomed, flexible, and waterproof cylindrical bag disposed extending vertically within the borehole, in which a soil mixture containing a hardening agent is stored; a first water pipe extending vertically along the outer surface of the cylindrical bag within the borehole, the first water pipe having a lower end connected to the lower end of the cylindrical bag in a communicating state; a vertically extending buoyancy resistance material extending vertically along the outer surface of the cylindrical bag within the borehole, the lower end of the resistance material being connected to the lower end of the cylindrical bag; and a reaction material supporting the upper end of the buoyancy resistance material to prevent the upper end from moving upward. A geothermal heat exchange device characterized in that the cylindrical bag, whose lower end is located at the bottom of the borehole, contains a heat transfer liquid having a lower specific gravity than the excavated soil mixture and the outer diameter of the cylindrical bag, when it is fully expanded, is set to be smaller than the inner diameter of the borehole, and the buoyancy acting on the cylindrical bag containing the heat transfer liquid present in the excavated soil mixture in the borehole is resisted by the buoyancy resistance material which is in a tensioned state between the lower end of the bag and the reaction material, thereby preventing the cylindrical bag from floating up.

3. The underground heat exchange device described in claim 1, characterized in that the buoyancy resistance material is configured as a steel cylindrical body extending vertically to accommodate the tubular bag body in the vertical direction, and the tubular bag body extending vertically is accommodated within the cylindrical body.

4. The underground heat exchange device described in claim 2, characterized in that the buoyancy resistance material is configured as a steel cylindrical body extending vertically to accommodate the tubular bag body in the vertical direction, the tubular bag body extending vertically is accommodated within the cylindrical body, and the first water pipe is arranged extending vertically while accommodated within the cylindrical body, or is arranged extending vertically along the outer surface of the cylindrical body.

5. The underground heat exchange device described in claim 3 or 4, characterized in that the steel cylindrical body is formed in a cylindrical shape by connecting axial reinforcing bars arranged upright at the required angular pitch in the circumferential direction with ring-shaped ring reinforcing bars at the required vertical intervals, and the axial reinforcing bars are connected to the ring reinforcing bars in a state of abutting the inner and / or outer peripheral surfaces of the ring reinforcing bars.

6. The steel cylindrical body is formed into a cylindrical shape by connecting axial reinforcing bars, which are set upright at the required angular pitch in the circumferential direction, with ring-shaped ring reinforcing bars at the required vertical intervals, and the axial reinforcing bars are connected to the ring reinforcing bars while abutting the inner and / or outer peripheral surfaces of the ring reinforcing bars, and all of the ring reinforcing bars have an introduction opening cut out on the same side when viewed from above, which can introduce the tubular bag body into the cylindrical body.This is an underground heat exchange device as described in claim 3.

7. The steel cylindrical body is formed into a cylindrical shape by connecting axial reinforcing bars, which are set upright at the required angular pitch in the circumferential direction, with annular reinforcing bars at the required vertical intervals, and the axial reinforcing bars are connected to the annular reinforcing bars while abutting the inner and / or outer peripheral surfaces of the annular reinforcing bars, and all of the annular reinforcing bars have introduction openings cut out on the same side when viewed from above, allowing the tubular bag body and the first water pipe to be introduced into the cylindrical body.The underground heat exchange device described in claim 4, characterized in that

8. A borehole is formed by injecting drilling fluid to excavate and mix the ground, and a mixture of excavated soil and sand containing hardening material is stored in the borehole. a waterproof cylindrical bag body extending in the vertical direction and having a bottomed cylindrical shape, and a flexible buoyancy resistance material having a lower end connected to a lower end of the cylindrical bag body, is successively lowered into the borehole; a heat transfer liquid having a specific gravity smaller than that of the excavated soil mixture is supplied into the cylindrical bag when the lower end of the bag reaches the bottom of the borehole, thereby expanding the cylindrical bag; With the excavated soil mixture liquid interposed between the outer peripheral surface of the expanded cylindrical bag and the inner peripheral surface of the borehole, the upper end of the buoyancy resistance material tends to float up together with the cylindrical bag due to the buoyancy acting on the cylindrical bag, but the upper end is supported by a reaction material installed at the upper end of the borehole to prevent the upper end from moving upward, and the tensioning action of the buoyancy resistance material, which is in a tensioned state between the lower end of the bag and the reaction material, prevents the cylindrical bag, which is connected to the lower end of the resistance material, from floating up, A construction method for an underground heat exchange device, characterized in that the reaction material is no longer needed after the tubular bag body has expanded to its maximum extent and is fixed in the borehole as the excavated soil mixture hardens due to the hardening action of the hardening agent.

9. A borehole is created by excavating the ground, and a mixture of excavated soil and sand containing hardening material is stored in it. a waterproof cylindrical bag body extending in the vertical direction and having a bottomed, flexible cylindrical shape is successively lowered into the borehole together with a first water pipe having a lower end of a water pipe connected in communication with the lower end of the cylindrical bag body, and a buoyancy resistance material having a lower end of a resistance material connected to the lower end of the bag body; a heat transfer liquid having a specific gravity smaller than that of the excavated soil mixture is supplied into the cylindrical bag when the lower end of the bag reaches the bottom of the borehole, thereby expanding the cylindrical bag; With the excavated soil mixture liquid interposed between the outer peripheral surface of the expanded cylindrical bag and the inner peripheral surface of the borehole, the upper end of the buoyancy resistance material tends to float up together with the cylindrical bag due to the buoyancy acting on the cylindrical bag, but the upper end is supported by a reaction material installed at the upper end of the borehole to prevent the upper end from moving upward, and the tensioning action of the buoyancy resistance material, which is in a tensioned state between the lower end of the bag and the reaction material, prevents the cylindrical bag, which is connected to the lower end of the resistance material, from floating up, A construction method for an underground heat exchange device, characterized in that the reaction material is no longer needed after the tubular bag body has expanded to its maximum extent and is fixed in the borehole as the excavated soil mixture hardens due to the hardening action of the hardening agent.

10. The buoyancy resistance material is configured as a steel cylindrical body extending vertically so as to be able to accommodate the cylindrical bag body in the vertical direction, and the cylindrical body is configured in a cylindrical shape by connecting axial reinforcing bars, which are set upright at a required angular pitch in the circumferential direction, with annular reinforcing bars at required vertical intervals, and the axial reinforcing bars are connected to the annular reinforcing bars in a state of abutting the inner and / or outer peripheral surfaces of the annular reinforcing bars, and all of the annular reinforcing bars have introduction openings cut out on the same side in a plan view so as to be able to introduce the bag body into the cylindrical body, and the lower end of the cylindrical body, which is the lower end of the cylindrical body, is the lower end of the resistance material, A construction method for an underground heat exchange device as described in claim 8, characterized in that as the cylindrical body is lowered into the borehole, the cylindrical bag body, whose lower end is connected to the lower end of the cylindrical body, is sequentially placed into the cylindrical body through the introduction opening in a state in which it extends in the vertical direction.

11. The buoyancy resistance material is configured as a steel cylindrical body extending vertically so as to be able to accommodate the cylindrical bag body in the vertical direction, and the cylindrical body is configured in a cylindrical shape by connecting axial reinforcing bars erected at a required angular pitch in the circumferential direction with annular reinforcing bars at required intervals in the vertical direction, and all of the annular reinforcing bars have introduction openings cut out on the same side in a plan view so as to be able to introduce the bag body into the cylindrical body, and the lower end of the cylindrical body, which is the lower end of the cylindrical body, is the lower end of the resistance material, A construction method for an underground heat exchange device as described in claim 9, characterized in that as the cylindrical body is lowered into the borehole, the cylindrical bag body, whose lower end is connected to the lower end of the cylindrical body, and the first water pipe are sequentially accommodated in the cylindrical body through the introduction opening, with the bags extending in the vertical direction.

12. 11. The method for constructing an underground heat exchanger according to claim 10, wherein the cylindrical bag introduced into the cylindrical body is prevented from escaping from the introduction opening by an escape prevention means.

13. A construction method for an underground heat exchanger according to claim 11, characterized in that an escape prevention means is used to prevent the tubular bag body and the first water pipe introduced into the tubular body from escaping from the introduction opening.

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