JP5339962B2 - Construction method for underground heat exchanger and hollow tube used in the method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ground heat exchange technology that uses geothermal heat for air conditioning, hot water supply, snow melting, etc., and in particular, construction of a ground heat exchanger that contains a heat exchange medium and is buried in the ground. The present invention relates to a hollow tube body for underground heat exchange that is buried in the ground by the method and the construction method.
In the present specification, the underground heat exchanger refers to a heat exchange medium disposed in the ground, members and devices for placing the heat exchange medium in the ground.

Performing air conditioning, hot water supply, snow melting, and the like using geothermal heat is a technique that has been performed conventionally, and has recently attracted attention as one of the uses of natural energy.
A general method of using geothermal heat is to arrange a heat exchange medium for exchanging heat with underground heat in the ground and use the heat of this heat exchange medium for the air conditioning or the like.

There are several modes for arranging the heat exchange medium in the ground, and a method using a borehole is widely used in Europe and America.
However, it is not so popular in Japan because of the high cost of drilling boreholes. In addition, when excavating a borehole, there is a risk of contaminating groundwater because mud or cement is used to protect the hole wall. Furthermore, the heat exchange tubes accommodated in the boreholes are buried and there is a problem in maintainability.

The following are proposed as another aspect of the underground heat exchanger.
(1) A spiral blade is provided at the tip of either the tip steel pipe or the drilled steel pipe, and the drilled steel pipe equipped with the tip steel pipe is rotated and press-fitted into the ground to reach a predetermined excavation depth. Insert the heat exchange tube into the hole steel pipe, and then reversely rotate the hole drilled steel pipe to separate the tip steel pipe and pull out and collect the hole drilled steel pipe and simultaneously fill the hole around the heat exchange tube with grout material A heat exchange tube is installed (see Patent Document 1).
According to the present invention, drilling is carried out with no drainage using a rotary press-fit steel pipe provided with spiral blades only at the tip, and after inserting a heat exchange tube into the drilling hole, the drilled steel pipe is filled with a grout material. Since the heat exchange tube can be inserted and installed in the drilling hole without a temporary casing, it can be removed from the tip steel pipe and removed, eliminating the need for soil disposal and reducing the cost of the heat exchange tube installation work. I can do it.

(2) Spiral blades for screwing piles having an outer diameter of 1.5 to 3 times the outer diameter of the pile body project one or more turns on the outer peripheral surface of the pile body, and further, excavation claw at the lower end of the pile The steel pipe pile for heat exchange which used the pipe for heat exchange in the pile hollow part using the steel pipe pile provided with (refer patent document 2).
According to this invention, it is supposed that the heat exchanging steel pipe pile which can transmit the underground heat more efficiently to the inside of the pile and is excellent in workability.

JP2002-303088 JP2004-177012

The thing of patent document 1 inserts a heat exchange tube in the excavation hole provided in the ground, and injects grout in the hole around it.
Thus, since the thing of patent document 1 grout material is directly inject | poured into the excavation hole provided in the ground, there exists a danger of contaminating groundwater.
Even if the heat exchanger is no longer used, it is difficult to dig up the grout material injected into the ground, so there is a risk that it will be left as it is, and it is not necessarily environmentally friendly.

On the other hand, the thing of the patent document 2 places the pile main body in the ground, and uses this as a heat exchanger, so as compared with the thing of the patent document 1 which injects the grout material directly into the ground as described above. There are few environmental problems.
However, the thing of the patent document 2 has the following problems.
The thing of patent document 2 needs to apply a rotational torque to a pile head like the construction of a normal rotation penetration pile. Therefore, it is necessary to make the pile plate thickness that can withstand the rotational torque applied to the pile head, and the pile material cost increases, which is uneconomical.
Moreover, since the thing of patent document 2 is only for an underground heat exchanger, since the supporting force required for a pile is not required, the blade | wing provided in a front-end | tip is only needed in order to obtain the thrust at the time of construction. Nevertheless, it remains buried in the ground after construction and is wasteful, which is also uneconomical.

Since the thing of patent document 2 embeds a pile body in the ground, when it stops using a heat exchanger, it can be said that it is easier to remove from the ground than the thing of patent document 1. .
However, the thing of patent document 2 has the following subjects regarding extraction of a pile body.
A heat exchange tube will be installed inside the pile. In order to prevent this heat exchange tube from being affected by solar radiation, it is generally necessary to install it below the ground surface. The pile head will also be constructed below the ground surface. In other words, when performing Yatco construction to rotate the pile, the pile head is buried in the ground, so it can be left as it is, but if the construction is completed with the pile head protruding from the ground surface, the head will be cut. Become.
In this way, the pile head is buried in the ground after construction, so when pulling out, the pile head rotation method excavates the ground around the pile head and attaches the rotating bracket. There is a problem that it takes time and effort.

  The present invention has been made to solve such problems, and is an environment-friendly construction method for an underground heat exchanger that does not contaminate groundwater or the ground, and to obtain a hollow tube used for the construction method. It is an object.

In the invention described in Patent Document 2, in the invention earlier than the present invention, the foundation pile as the structure and the underground heat exchanger were combined, whereas the pile body was used as the underground heat exchanger. This is a new concept in that it is used exclusively.
According to such a way of thinking, since the supporting force is not required for the pile body, the pipe thickness can be reduced accordingly.
However, since the thing of patent document 2 exists in the range of the idea of the conventional pile body, the steel pipe which comprises a pile body is buried in the ground with the function of excavating a hole in the ground, and the underground heat which accommodates a heat exchange medium It is required to have a function as an exchanger.
In order to exhibit the function of excavating a hole, it is necessary to transmit the rotational torque for excavation over the entire length, and thus the steel pipe is required to have a thickness sufficient to withstand the rotational torque. In particular, when the pile length is long and deep, or when it is placed on a hard ground such as a gravel layer, a large torque is required, and a large plate thickness and strength that can withstand it are necessary.
On the other hand, considering the heat exchange in the ground, it can be said that the thinner the steel pipe, the better the heat transfer.
As described above, the functions necessary for excavating the hole and the functions as the heat exchanger are required to be contradictory, but this has been conventionally performed with a single member, which is uneconomical and low. It was efficient.
Therefore, the inventor has paid attention to this point, and has obtained the knowledge that by separating the conflicting functional members, a highly efficient and highly efficient heat exchanger and its construction method can be realized.
The present invention is based on such knowledge, and specifically comprises the following configuration.

(1) The construction method of the underground heat exchanger according to the present invention includes an underground heat exchange in which a heat exchange medium is accommodated and buried in the ground to exchange heat between the underground heat and the heat exchange medium. The body construction method,
A hollow tube body fitting step of fitting a hollow tube body constituting the underground heat exchanger inside a cylindrical casing having a function of penetrating into the ground, and the inside of the casing together with the penetration of the casing into the ground An embedding step of burying an empty tube in the ground, a casing extracting step of extracting only the casing after the hollow tube is embedded at a predetermined depth, and a heat exchange tube in the hollow tube And a step of inserting the .

(2) In the above (1), the casing has wings at the tip and / or outer periphery thereof, and in the embedding step, the casing is rotationally inserted into the ground. .

(3) Further, in the above (1) or (2), the hollow tube fitting step includes a connecting step of connecting the casing and the hollow tube, and the casing extraction step releases the connection. A connection releasing step is included.

(4) Further, in the above described (3), the connecting step is to lock the locking protrusion provided at the lower end portion of the hollow tubular body into the engaging hole provided at the lower end portion of the casing. Yes, the connection releasing step is to release this locking.

(5) The hollow tube of the underground heat exchanger according to the present invention is a hollow tube used in the construction method of the underground heat exchanger according to any one of the above (1) to (4). And it has the latching | locking part which can be detachably latched with a casing, It is characterized by the above-mentioned.

(6) Further, in the above (5), a locking portion capable of transmitting rotational force and / or pulling force to the hollow tube body is provided on the inner surface of the lower end of the hollow tube body. To do.
As a specific example of the position where the locking portion is provided, for example, when the diameter of the hollow tube is D, the locking portion is within the range of 2D at the lower end.

(7) Moreover, in the thing in any one of said (5)-(6), a hollow pipe body is a steel pipe, It is characterized by the above-mentioned.

According to the construction method of the underground heat exchanger of the present invention, the hollow tube is disposed inside the casing having a function of penetrating into the ground, and the hollow tube is buried in the ground together with the penetration of the casing into the ground. Then, after the hollow tube body was buried at a predetermined depth, only the casing was extracted, so in the process of embedding in the ground, a large torque does not act on the hollow tube body, The thickness of the member forming the hollow tube can be reduced, the cost can be reduced, and the heat transfer rate is improved, so that the heat exchanger is highly efficient.
In addition, since a hollow tube is used as an underground heat exchanger, it is environmentally friendly without contaminating groundwater or the ground as in the case of injecting a grout material directly into a hole provided in the ground.

It is a schematic diagram explaining the construction tool used for the construction method of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the construction method of the underground heat exchanger which concerns on one embodiment of this invention. It is arrow AA sectional drawing of FIG. It is explanatory drawing of the other aspect of the construction method of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the construction method of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the process of embedding the hollow pipe body in the construction method of the underground heat exchange body which concerns on one embodiment of this invention. It is explanatory drawing of the insertion method of the heat exchange tube in the construction method of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the drawing-out method of the hollow tube which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the drawing-out method of the hollow tube which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the drawing-out method of the hollow tube which concerns on one embodiment of this invention. It is a graph which shows the experimental result which confirms the effect of the form of the wing | blade in one embodiment of this invention. It is explanatory drawing explaining the effect of the form of the wing | blade which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the process of the aspect of the construction method of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the underground heat exchanger which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the underground heat exchanger which concerns on one embodiment of this invention.

FIG. 1 is a schematic view showing a part of the instrument used in the construction method of the underground heat exchanger according to one embodiment of the present invention.
An instrument used in the construction method according to the present embodiment includes a hollow tube 1 that is buried in the ground and becomes a part of a heat exchanger, and a wing for burying the hollow tube 1 in the ground. A casing 3 is provided.
Hereinafter, each configuration will be described in detail.

<Winged casing>
The winged casing 3 is a dedicated instrument for embedding the hollow tube body 1 in the ground, and includes a casing main body portion 5 made of a cylindrical steel pipe and a wing 7 provided on the lower peripheral surface thereof. This is a structure.
The winged casing 3 has a strong connection to the main body of the wing 7 so that it can be constructed even on hard ground such as gravel with an N value exceeding 50, and can be subjected to a larger torque than normal pile construction. Increase the plate thickness sufficiently.
Thereby, it can be set as the casing 3 with a wing | blade with good penetrability in the way of a wood screw using a big torque.

The plate thickness of the casing main body 5 is desirably about 1.5% to 10% of the casing diameter, and is preferably as thick as possible in the production range. It is preferable to use a high-strength material because the range of torque that can be withstood is widened.
It is desirable that the inner diameter of the casing body 5 is set to be slightly larger than the outer diameter of the hollow tube 1 so as not to contact the hollow tube 1 during construction. For example, it is desirable that D1 = 1.2 to 2D with respect to the outer diameter D of the hollow tube 1.
The wings 7 attached to the casing body 5 may be spiral or flat and may be provided in a plurality of stages. The wing 7 may be a continuous one like a spiral auger, but if it is attached over the entire length, the soil will be discharged from the ground, so that there are about 2-3 turns around the tip of the casing body 5. Is preferred. Further, the blades 7 are not continuous, and may be discontinuously attached to the tip portion or the intermediate portion.
The diameter of the blade 7 is preferably about 1.2 to 3 times the diameter of the casing body 5.

  At the lower part of the casing body 5, there is provided an engagement hole 9 into which a locking projection 21 of the hollow tube 1 described later can be inserted and locked. The engagement hole 9 is formed in a substantially T shape by a leg portion 11 opened at the lower end edge of the casing body portion 5 and an arm portion 13 provided at the upper portion thereof. The width of the leg portion 11 of the engagement hole 9 is set to be larger than the width (circumferential direction) of the locking projection 21 of the hollow tube body 1, and the height (width in the vertical direction) of the arm portion 13 is It is set slightly larger than the thickness (vertical direction) of the stop protrusion 21. By setting in this way, the locking projection is inserted from the lower side of the leg of the engagement hole 9 and can be inserted to the left and right of the arm 13. The locking projection 21 and the engagement hole 9 having such a relationship constitute an attachment / detachment mechanism for connecting or disconnecting the casing body 5 and the hollow tube 1.

<Hollow tube>
The hollow tube body 1 constitutes a ground heat exchanger that exchanges heat between the ground heat and the heat exchange medium by accommodating the heat exchange medium and being buried in the ground.
The hollow tube 1 is a bottomed cylindrical body having a circular cross section in which a bottom plate 14 is provided at a lower end and an upper end is opened. However, the cross-sectional shape of the hollow tube body 1 is not particularly limited as long as it is a shape that can contain, for example, a heat exchange tube that allows a heat exchange medium to flow therethrough, or water that fills the periphery of the heat exchange tube. Besides, it may be a square or a polygon. Further, in order to increase the heat exchange efficiency, the whole may have a bellows shape, or may have a structure with fins attached thereto.
The material forming the hollow tube 1 may be any material that can exchange heat between the heat exchange medium accommodated in the hollow tube 1 and the underground heat, such as steel or resin. Good.
As described above, the shape material of the hollow tube 1 is not particularly limited, but it is generally desirable to use a circular steel pipe having a high thermal conductivity and a low cost.

The diameter, the number, and the length of the hollow tube 1 are determined according to the load required for air conditioning design.
The diameter of the hollow tube 1 is not particularly limited, but is preferably about φ80 mm to φ600 mm in consideration of the construction cost and the cost of the winged casing 3.
However, since the contact area with the ground greatly affects the amount of heat that can be obtained, the total amount of heat that can be obtained is increased by creating multiple small diameters rather than creating a large-diameter underground heat exchanger. It is desirable to take this into consideration.
In addition, since the number of heat exchange tubes put in the hollow tube 1 also affects the amount of heat obtained, it is desirable to determine the diameter of the hollow tube 1 in consideration of this number.
In general, when the hollow tube 1 has an inner diameter of up to about φ200 mm, one heat exchange tube of about φ30 mm is inserted (one pair, see FIG. 7). It is desirable to use a plurality of heat exchange tubes. As the heat exchange tube, a polybutene tube or a crosslinked polyethylene tube is generally used. In consideration of workability, maintainability, thermal conductivity, and cost, the best material should be used.

When the total length of the underground heat exchanger is long, the construction is performed while the hollow tube 1 and the casing body 5 are connected. In this case, since it is necessary to connect so that the water etc. which are filled in the hollow tube 1 do not flow out to the ground, welding connection is good when the hollow tube 1 is a steel pipe. However, another joining method may be used as long as the structure can maintain the sealing property of the connecting portion.
The casing body 5 is preferably a mechanical joint joint. Since the casing main body 5 is pulled out and reused after the hollow tube body 1 is buried at a predetermined depth, welding the joint portion takes time in operations such as gas cutting and groove reworking. This is because it is more convenient to use a joint.

Since a large torque acts on the casing body 5 at the time of construction, a mechanical joint having a structure capable of withstanding the large torque is used. FIG. 2 is a view showing an example of a mechanical joint, and FIG. 3 is an AA view of FIG. 2. As shown in FIGS. 2 and 3, the connection method using the flange 15 and the bolt 17 is also possible. good.
Further, as shown in FIG. 4, a method of connecting the casing body parts 5 with only the bolts 19 may be used, or a threaded joint in which a threaded part is provided at the connection end of the casing body part 5 and these are screwed together. It is good.
In addition, when this mechanical coupling protrudes inside the casing main-body part 5, it is necessary to leave sufficient distance between both so that this mechanical coupling may not collide with an outer surface of a hollow pipe body.

  In the present embodiment, since the construction is performed using the winged casing 3, almost no torque acts on the main body of the hollow tube 1. Therefore, it is natural that the thickness of the hollow tube 1 of the present embodiment can be made thinner than a pile that also serves as an underground heat exchanger, but compared with that shown in Patent Document 2. But it can be made even thinner. Therefore, when using a steel pipe as the hollow tubular body 1, it is not necessary to use a high-strength one, as long as the thickness is such that there is a hole due to corrosion and does not leak water, etc. A thickness of about 5% or a thickness of about 2 to 10 mm is sufficient.

In order to rotate and penetrate the winged casing 3 together with the winged casing 3, the hollow tubular body 1 has a hollow prismatic locking projection 21 for transmitting the torque, pushing force, and pulling force of the winged casing 3. It is provided so as to protrude to the outer surface side of the tube body 1. Since a certain amount of torque acts on the locking projection 21, it is necessary for the distal end portion of the hollow tube body 1 to have strength. For example, it is better to increase the plate thickness.
The position at which the locking projection 21 is provided is preferably provided in a range of about 1D (D: diameter of the hollow tube 1) from the lower end of the hollow tube 1.
In addition, the locking protrusion 21 may be provided at one or more locations, but it is desirable to provide about 2 to 4 locations in order to reliably transmit torque. In addition, since the hollow tube body 1 may not be stable when the number of places where the locking projections 21 are provided is less than 3, it is desirable to provide a spacer or the like and perform the construction as stably as possible at the center position.
As described above, the lower end portion of the hollow tube body 1 is covered with the bottom plate 14 such as a steel plate. However, in order to facilitate penetration into the ground on the lower surface side of the bottom plate 14, the soil is discharged to the outside during penetration. A triangular plate 22 as shown in FIG. 5 may be provided, the excavating blade may be attached to the lower part of the casing or the wing, or the tip may be drilled. The tip is preferably made of steel, and may be separately produced by casting.

<Removal mechanism>
As described above, the casing body 5 and the hollow tube 1 are connected by the engagement hole 9 provided in the winged casing 3 and the locking projection 21 provided in the lower portion of the hollow tube 1. An attachment / detachment mechanism for separating and separating is configured.
Hereinafter, the operation of the attachment / detachment mechanism will be described in detail.
The winged casing 3 is fitted to the outside of the hollow tube body 1 from above, the leg 11 of the engagement hole 9 is aligned with the position of the locking projection 21, and the winged casing 3 is moved downward in this state. The locking projection 21 is positioned in the arm portion of the engagement hole 9. In this state, the winged casing 3 is rotated, for example, in a clockwise direction (hereinafter referred to as a positive direction), and the locking projection 21 is moved to one side (right end in FIG. 1) of the arm portion 13 of the engagement hole 9. Position. As a result, the locking projection 21 is locked in the engagement hole 9, and the hollow tube 1 and the winged casing 3 are integrally connected (see FIG. 1).

In the integrally connected state, if the winged casing 3 is lowered or raised, the hollow tube body 1 is also lowered or raised together. That is, the pushing force and pulling force of the winged casing 3 can be transmitted to the hollow tube 1.
Further, when the winged casing 3 is rotated in the forward direction, the rotational torque of the winged casing 3 is transmitted to the hollow tubular body 1 via the locking projection 21 and the hollow tubular body 1 is rotated in the forward direction. To do.
Further, when the winged casing 3 is rotated counterclockwise (hereinafter referred to as a reverse direction) from the state shown in FIG. 1, the locking projection 21 moves in the reverse direction in the arm portion of the engagement hole 9. Lock to the other end (left end in FIG. 1). If the winged casing 3 is further rotated in the reverse direction in this state, the hollow tube 1 can be rotated in the reverse direction.

<Construction method>
FIG. 6 is an explanatory view for explaining a construction method for constructing the hollow tube 1 configured as described above into the ground using the winged casing 3.
Hereinafter, this construction method will be described with reference to FIG. 6 and FIGS.
First, as shown in FIG. 6 (a), the hollow tube body 1 is disposed at a planned embedding position on the ground, and a winged casing 3 is fitted into the hollow tube body 1 so that the inside as described above. The locking projection 21 of the hollow tube 1 is locked in the engagement hole 9 of the casing body 5, and the hollow tube 1 and the winged casing 3 are connected together.
And the head of casing 3 with wings is connected to rotation motor 25 of construction machine 23 via a connector which is not illustrated.

In this state, if the rotary motor 25 is rotated in the forward direction to drive the winged casing 3 to rotate, the winged casing 3 is penetrated into the ground by the screw action of the wings 7 (see FIG. 6B). . At this time, the rotational force and pushing force of the winged casing 3 are transmitted to the hollow tubular body 1 through the transmitting portion, and the hollow tubular body 1 penetrates into the ground together with the winged casing 3. As described above, since the hollow tube 1 also rotates when it penetrates into the ground, as shown in FIG. 5, a triangular plate or the like is provided at the lower portion of the hollow tube 1, thereby excavating the triangular plate or the like. Thus, the hollow tube body 1 can penetrate more smoothly.
In addition, there is a gap between the hollow tube 1 and the casing body 5, but since this gap is not so large, soil does not enter the gap and soil enters the gap and becomes resistance. There is no.
The head of the hollow tube 1 during construction is free, and the outer peripheral surface of the hollow tube 1 and the inner peripheral surface of the casing main body 5 may come into contact with each other. A spacer or the like may be appropriately provided on the outer wall of the hollow tube 1 or the inner wall of the casing body 5.

  The hollow tube body 1 functions as a heat exchanger and does not require a tip support force or a peripheral friction force in a state after being embedded like a pile. Therefore, at the time of rotation penetration into the ground by the casing 3 with wings, in order to increase the construction speed, the construction may be performed by frequently moving up and down by reverse rotation or the like. However, it is necessary to prevent soil from being discharged to the ground or disturbing the groundwater flow.

When the total length of the underground heat exchanger is long, as shown in FIG. 6C, the construction is performed while the hollow tube 1 and the casing body 5 are added. In this example, two hollow tube bodies 1 and two casing main body portions 5 are connected. FIG. 6 (d) shows a state where the hollow tube body 1 and the casing body 5 are joined and then rotated to penetrate to a predetermined depth.
When the penetration to a predetermined depth is completed, a slight pulling force is applied to the winged casing 3 so as to disconnect the engagement protrusion 21 of the hollow tube 1 and the engagement hole 9 of the casing body 5. By slightly rotating, when the locking projection 21 comes to the position of the leg 11 of the engagement hole 9, the connection between the two is released. When the connection between the two is disengaged, the winged casing 3 is rotated and pulled up, so that only the winged casing 3 can be recovered while leaving the hollow tube 1 in its position (FIGS. 6E and 6F). )reference).
The gap between the ground after the winged casing 3 is pulled out and the hollow tube body 1 is usually small and disappears naturally. However, if necessary, when the casing 3 is pulled out, sand, gravel, It is also possible to fill this gap with a mixture of water and soil mixed with a material with good thermal conductivity.

When the construction of the hollow tube 1 is completed, as shown in FIG. 7, the heat exchange tube 27 is inserted into the hollow tube 1 (see FIG. 7A), and water is poured into the hollow tube 1. If it fills (refer FIG.7 (b)), an underground heat exchanger will be completed.
By repeating the same construction a plurality of times, it is possible to form an underground heat exchanger group corresponding to the designed load.
In addition, it is desirable to install the heat exchangers in various places apart from each other by about 1 m or more so as not to receive mutual heat action. Further, when the heat exchange tube 27 is piped to the heat pump, it is affected by solar radiation, so it is desirable to bury it in about 1 m underground. Considering the influence of solar radiation, if the underground heat exchanger is installed in the shade, such as the north side of the building, it will be less susceptible to the influence of solar radiation and can effectively use the underground heat.

As mentioned above, in the construction method of the underground heat exchanger according to the present embodiment, the hollow tube body 1 is disposed inside the winged casing 3 having a function of penetrating into the ground, and the winged casing 3 Since the hollow tube body 1 is buried in the ground with the penetration into the ground, and the hollow tube body 1 is buried at a predetermined depth, only the winged casing 3 is extracted. In the embedding process, since a large torque does not act on the hollow tube body 1, the thickness of the member forming the hollow tube body 1 can be reduced, and the cost can be reduced and the heat transfer rate is improved. It becomes high efficiency as a heat exchanger.
In addition, since the winged casing 3 can be used repeatedly, even if a thick-walled casing 3 is manufactured to allow the winged casing 3 to penetrate various grounds, for example, hard ground, the cost can be greatly increased. Rather, the cost can be reduced by improving the work efficiency.

  Further, in the present embodiment, since the winged casing 3 with the wings 7 attached in the vicinity of the tip is used, it is possible to perform soil-free construction. Therefore, it is not necessary to use cement milk or the like. Environmentally friendly without having to.

In addition, the underground heat exchanger according to the present embodiment pulls out the hollow tube 1 when it becomes unnecessary due to renewal of a building or an air conditioner or when it is necessary to move the installation location. Can be easily removed, and can be used as an underground heat exchanger by re-installing in another place.
In order to make it easy to pull out the hollow tube 1, as shown in FIG. 8, a locking projection 29 for transmitting rotational torque and pulling force is provided near the lower end of the inner surface of the hollow tube 1. It is desirable to provide it. One or more locking protrusions 29 may be provided. When pulling out the hollow tube 1, for example, as shown in FIG. 8, a pulling rod 33 having an engagement hole 31 that can be engaged with the locking projection 29 at the tip is used. The engagement hole 31 provided at the tip of the extraction rod 33 may be a T-shape similar to the engagement hole 9 provided in the winged casing 3. Note that the engagement hole 31 and the locking projection 29 may have any shape as long as the torque and the pulling force necessary for pulling out the hollow tube 1 can be applied.

The drawing operation of the hollow tube 1 is performed as follows.
First, the heat exchange tube 27 is pulled out from the hollow tube body 1, the filling water in the hollow tube body 1 is pumped up with a pump or the like, and the extraction rod 33 is inserted into the hollow tube body 1 that has become empty. Although the pulling rod 33 can be inserted without pumping up the filling water, the workability is better when pumping up first.
The pulling rod 33 is inserted, the engaging hole 31 and the locking projection 29 are locked, and in this state, the pulling rod 33 is rotated by a heavy machine motor on the ground. As a result, the frictional edge between the hollow tube 1 and the ground is cut, and if the hollow tube 1 is pulled up with the edge cut, the hollow tube 1 can be easily pulled out.

When pulling out the hollow tube 1, it is conceivable to apply a rotational force to the head of the hollow tube 1, but in this case, a frictional force acting on the entire length of the hollow tube 1 is applied to the hollow tube 1. Since it acts as a resistance (because both the head and the tip of the hollow tube 1 are fixed points), the plate thickness of the hollow tube 1 is thin, so that the friction edge between the hollow tube 1 and the ground is There is a risk that the hollow tube 1 may be broken before it is cut. In particular, in Patent Document 2 having a wing at the tip, since the resistance of the wing is large, if the plate thickness is thin, the blade is broken.
In this regard, as shown in FIG. 8, if a rotational force is applied to the lower end of the hollow tube 1, the edge of friction gradually cuts from the lower end of the hollow tube 1 (the pile head is free). In this case, only the tip of the pile becomes a fixed point), and so much torque does not act on the hollow tube.
Further, if the edge of the peripheral friction is cut, the hollow tube body 1 is easily pulled out, so that even if the wing 7 is not attached like a pile with wings, there is no hindrance to the drawing work. Since the drawn hollow tube 1 can be reused in another place, it is an environmentally friendly method.

  Note that the attachment / detachment mechanism between the inner surface of the hollow tube 1 and the drawing rod 33 for pulling out the hollow tube 1 is not limited to that shown in FIG. Any other structure may be used as long as it can apply a rotational force and can move upward integrally with the extraction rod 33. For example, as shown in FIG. 9, a T-shaped T-shaped projection 35 is provided at a position opposite to the inner surface tip of the hollow tube 1, and the bottom surface of the hollow tube 1 and the shoulder of the T-shaped projection 35 are provided. A pulling rod 39 provided at the tip of a square member 37 that can be fitted between the two is provided with a rotational force and may be pulled out. Further, as shown in FIG. 10, an L-shaped protrusion 40 may be provided instead of the T-shaped protrusion 35 of FIG.

Moreover, as an example of the wings 7 attached to the casing body 5, in the above embodiment, an example in which one spiral wing is provided is shown, but the wings 7 according to the present invention are not limited to this. The shape may be a flat plate shape, and a plurality of steps may be provided.
The wings 7 may be continuous like a spiral auger, but if they are attached over the entire length, the soil will be discharged from the ground, so that there are about 2-3 turns around the tip of the casing body 5. Is preferred. Further, the blades 7 are not continuous, and may be discontinuously attached to the tip portion or the intermediate portion.

FIG. 11 is a graph showing experimental results obtained by examining changes in torque during construction when the shape and the number of stages of the blades are variously changed. The horizontal axis shows the torque during construction (kN · m), and the vertical axis shows the penetration depth (mm). In the graph, (A) shows a case where one stage with a blade diameter twice the casing body diameter is provided, and (B) shows a case where three stages with a blade diameter twice the casing body diameter are provided continuously. (C) is a case where a blade whose diameter is twice the casing body diameter is provided in the first stage and a blade whose diameter is 2.5 times the casing body diameter is discontinuously provided in the second stage. Is a case where two blades having a blade diameter twice the casing body diameter are provided non-continuously.
As can be seen from FIG. 11, in the soil tank test using the model pile conducted by the inventor, the shape with the two-stage spiral wings that are not continuous rather than the one-stage spiral wings was constructed under the same conditions. The torque can be reduced. FIG. 12 is an explanatory diagram for explaining this mechanism. In the first stage blade, as shown in FIG. 12 (a), the soil sent upward by the blade 7 cannot be moved to the side, so it is compacted and the peripheral frictional force is increased by pressing the steel pipe from the circumferential direction. On the other hand, as shown in FIG. 12 (b), when the discontinuous blade 7 is provided, the upper blade 7 stirs the ground again to reduce the peripheral frictional force. Therefore, it can be estimated that the torque during construction can also be reduced. For this reason, it is desirable in terms of construction that the blades 7 are mounted in a plurality of stages in a discontinuous manner.

  The distance between the blades 7 when discontinuous is about 1 to 5 times the outer diameter D1 of the casing body 5 as a guide. Also, the step between the start and end of the wing 7 is preferably about 0.1 to 1 times the pile diameter. Furthermore, the winding direction of one wing 7 in the circumferential direction is generally about 270 ° to 450 °, but considering the ease of movement of soil, the spacing is larger at 360 ° or less. So good. Further, the diameter of the blade 7 is preferably about 1.2 to 3 times the diameter of the casing body 5.

  Also, when providing multiple stages of blades, in the conventional pile, comparing the blade diameter of the first stage (bottom stage) with the blade diameter of the second stage (upper stage), the blade diameter of the second stage is increased. The shape is determined so that more support force can be obtained even when the torque is increased. However, in the present invention, it is not necessary to obtain a supporting force and it is only necessary to perform the construction of a predetermined length. Therefore, the shape may be determined so that the rate of torque reduction during construction is increased. In this regard, as shown in FIG. 11 which shows the experimental results performed by the inventor, the construction torque is smaller in the case of (D) than in the case of (C). It was found that the torque reduction rate during construction was greater when the blade diameter at the stage was the same.

In the above embodiment, when the casing body 5 is mechanically jointed, as shown in FIG. 4, the mechanical joint is a casing as a method of connecting the casing body 5 only with the bolt 19. The case where it protrudes inside the main-body part 5 was shown. In this case, as described above, it is necessary to provide a sufficient distance between the two so that the mechanical joint does not collide with the outer surface of the hollow tube body.
However, in the present invention, the casing body 5 does not require a peripheral frictional force with the ground unlike a pile, so that the mechanical joint projects to the outside of the casing body 5 as shown in FIG. There is no problem.

In the above-described embodiment, a T-shaped engagement hole 9 is provided in the winged casing 3 as a mechanism for attaching and detaching the hollow tubular body 1 and the winged casing 3, The example which provides the part 21 was shown.
In such an attachment / detachment mechanism provided with the T-shaped engagement hole 9, when the casing main body 5 and the hollow tube body 1 are separated, the casing main body 5 in order to be positioned on the leg 11 of the locking protrusion 21. Needs to be rotated relative to the hollow tube 1. In a relatively loose sand ground or the like, the casing body 5 and the hollow tube 1 can be attached and detached without rotating together, but when clay or the like adheres, the casing body 5 and the hollow tube 1 are separated. If the hollow tube body 1 is fixed or the casing main body 5 is not rotated in the reverse direction, it is difficult to separate the casing body 5 together.

Therefore, as shown in FIG. 14, a rectangular engagement hole 91 that is not cut in the steel pipe axial direction instead of the T-shape may be provided. With such a rectangular engagement hole 91, when the casing body 5 and the hollow tube 1 are separated, the hollow tube 1 can be easily separated from the casing body 5 by pushing the hollow tube 1 downward.
Depending on the hardness of the ground at the time of construction, the workability may be improved by repeating forward and reverse rotation of the casing body 5 or by moving up and down. When the vertical movement is performed, when the engagement hole 91 is provided, the locking projection 21 of the hollow tubular body 1 is caught on the casing body 5 side unlike the case of the T-shaped engagement hole 9. Therefore, there is a possibility that the hollow tube 1 falls into the ground. In such a case, as shown in FIG. 15, if a padding 42 such as clay or silicon is packed in advance in the gap between the engagement hole 91 or the casing body 5 and the hollow tube 1, the vertical movement is performed. The hollow tube 1 does not fall. Also, if the presence of cohesive ground is confirmed in the preliminary ground survey, clay will naturally clog during construction, and the hollow tube body 1 will not fall during vertical movement, so dare to fill clay etc. You don't have to work.

FIG. 16 is an explanatory diagram of a construction method when the engagement hole 91 shown in FIG. 14 is provided.
Hereinafter, this construction method will be described with reference to FIG. 16 and FIG. 14 described above.
First, the hollow tube body 1 is arranged at a planned embedding position on the ground, and the casing 3 with wings is fitted into the hollow tube body 1, and the locking projection 21 of the hollow tube body 1 is connected to the casing body portion 5. The engagement holes 91 are engaged. In this state, the winged casing 3 is rotationally driven to penetrate the winged casing 3 into the ground (see FIG. 16A).

When the total length of the underground heat exchanger is long, as shown in FIG. 16 (b), construction is performed while the hollow tube 1 and the casing body 5 are added. In this example, two hollow tube bodies 1 and two casing main body portions 5 are connected. FIG. 16C shows a state in which the hollow tube body 1 and the casing main body portion 5 are joined and then rotated and penetrated further.
After the winged casing 3 reaches a predetermined depth, the winged casing 3 is pulled up several tens of centimeters together with the hollow tube 1 to make the ground below the winged casing 3 loose, and in this state the hollow tube 1 Push down. As a result, the hollow tube 1 is detached from the engagement hole 91 of the casing body 5 and can be easily installed at a predetermined position (see FIG. 16D).
If the ground at a predetermined depth is weak, the hollow tube body 1 can be pushed in without pulling up the winged casing 3, but if it is hard, a large force is required to push it in. Then, it is better to raise the winged casing 3 slightly. Since the winged casing 3 and the hollow tube 1 are bonded together with clay or the like, the hollow tube 1 will not be displaced arbitrarily even if the reverse rotation is pulled up. .
After the hollow tube 1 is installed at a predetermined depth, the winged casing 3 is rotated and pulled up, so that only the winged casing 3 can be recovered while leaving the hollow tube 1 in its position (FIG. 16). (See (e) and (f)).

In the above embodiment, the example in which the locking projection 21 is provided on the hollow tube 1 has been shown. However, as shown in FIGS. 17A and 17B (viewed from the bottom side), the bottom plate 14 may be provided with a locking projection 21. In this case, if the bottom plate 14 is attached so as to match the inner diameter of the casing body 5, there is almost no earth and sand between the casing body 5 and the hollow tube 1, and the construction is not hindered. . In addition, since torque acts on the bottom plate 14 via the locking projection 21, it is not necessary to increase the plate thickness of the hollow tube 1.
Further, as shown in FIGS. 17C and 17D (viewed from the bottom surface side), a substantially T-shaped locking protrusion 21a is provided on the inner surface of the casing in a side view, and locked to the bottom plate 14. You may make it the structure which provides the latching recessed part 21b which can insert the T-shaped leg part of the protrusion 21a. In this case, the same effect as described above is obtained. Further, in this case, since it is not necessary to provide the engagement hole 91 in the casing, the surroundings of the engagement hole 91 are reinforced as in the case where the engagement hole 91 is provided in the casing when a large torque is applied. No response is required.

  If the bottom plate 14 does not require a drilling function such as a triangular plate depending on the ground conditions and is not attached, as shown in FIGS. 18 (a) and 18 (b) (viewed from the upper end side). The locking protrusions 21 and 21a may be eliminated, and an inner surface protrusion 43 that restricts the upward movement of the bottom plate 14 may be provided inside the casing body 5. The inner surface protrusions 43 may be arranged discretely or attached in a continuous ring shape. Moreover, you may pack clay etc. in the inner surface of the baseplate 14 and the casing main-body part 5 as needed.

  The attachment / detachment mechanism of the present invention is not limited to the above-described one, and the hollow tube 1 can be moved up and down integrally with the winged casing 3 and, if necessary, the hollow tube Other structures may be used as long as the body 1 can be left and only the winged casing 3 can be pulled up.

  In the above embodiment, the hollow tube body 1 and the winged casing 3 are connected to allow the hollow tube body 1 to penetrate into the ground simultaneously with the penetration of the winged casing 3. In the case of a simple ground, the hollow tube body 1 is not attached to the winged casing 3 by connecting the winged casing 3 by separately applying a pushing force to the hollow tube body 1 without connecting the winged casing 3 and the hollow tube body 1. May penetrate into the ground. That is, in this case, only the winged casing 3 is rotated and inserted, and the hollow tube 1 is press-fitted by the pressure input of the construction machine 23. When such construction is possible, the attachment / detachment mechanism between the winged casing 3 and the hollow tube 1 can be omitted.

  For filling the hollow tube, water is advantageous from the viewpoint of maintenance and cost, but it is desirable to select a material having good thermal conductivity when used as a ground heat exchanger. Therefore, concrete or mortar may be filled instead of water. If concrete is filled, the heat exchange characteristics will be higher than that of water, so the efficiency of the underground heat exchange system will increase.

  However, in this case, maintenance of the heat exchange tube 27 becomes difficult. Therefore, when a failure occurs in the heat exchange tube 27, the hollow tube 1 itself is replaced. In this case, the hollow tube body 1 is pulled out from the ground. However, since the hollow tube body 1 is filled with concrete, there is a risk of damage due to torque even if the hollow tube is thin. Therefore, the pile head can be pulled out easily by applying a rotational torque. And if a new hollow tube is driven in the extracted place, it can be utilized again as a ground heat exchanger.

  Certainly, when the hollow tube 1 is filled with concrete or the like, it can be said that the maintainability is worse than when water is filled, but the concrete is accommodated in the hollow tube 1. As in the case of directly injecting grout into the excavation hole provided in the ground described in Patent Document 1, there is no risk of groundwater contamination, and it is easy to remove as described above. It can be said that it is easy.

  Further, as another example of filling the hollow tube body 1, soil such as sand may be filled. In this case, since the work can be easily performed by scraping or digging up the soil with a water jet or the like during maintenance, the maintenance can be performed.

DESCRIPTION OF SYMBOLS 1 Hollow tube 3 Wing casing 5 Casing main-body part 7 Wing | blade 9 Engagement hole 11 Leg part 13 Arm part 14 Bottom plate 15 Flange 17 Bolt 19 Bolt 21, 21a Locking protrusion 22 Triangular plate 23 Construction machine 25 Rotating motor 27 Heat Exchange tube 29 Locking protrusion 31 Engagement hole 33 Pull-out rod 35 T-shaped protrusion 37 Square member 39 Pull-out rod 40 L-shaped protrusion 42 Stuffing 43 Inner surface protrusion 91 Engagement hole

Claims (7)

It is a construction method of a ground heat exchanger that performs heat exchange between ground heat and the heat exchange medium by containing a heat exchange medium and buried in the ground,
A hollow tube body fitting step of fitting a hollow tube body constituting the underground heat exchanger inside a cylindrical casing having a function of penetrating into the ground, and the inside of the casing together with the penetration of the casing into the ground An embedding step of burying an empty tube in the ground, a casing extracting step of extracting only the casing after the hollow tube is embedded at a predetermined depth, and a heat exchange tube in the hollow tube A method for constructing a subterranean heat exchanger, comprising:   The construction method of the underground heat exchanger according to claim 1, wherein the casing has blades at a tip portion and / or an outer peripheral portion thereof, and the casing is rotationally inserted into the ground in the embedding step.   The hollow tube body fitting step includes a connection step of connecting the casing and the hollow tube body, and the casing extraction step includes a connection release step of releasing the connection. Construction method of underground heat exchanger.   The connecting step is to lock the locking protrusion provided at the lower end of the hollow tube into the engaging hole provided at the lower end of the casing, and the connection releasing step is to release this locking. The construction method of the underground heat exchanger of Claim 3 characterized by these.   It is a hollow tube used for the construction method of the underground heat exchanger as described in any one of Claims 1-4, Comprising: It has a latching | locking part which can be detachably latched with a casing. Hollow tube of underground heat exchanger.   The hollow of the underground heat exchanger according to claim 5, wherein a locking portion capable of transmitting a rotational force and / or a pulling force to the hollow tube is provided on an inner surface of a lower end of the hollow tube. Tube. The hollow tube of the underground heat exchanger according to any one of claims 5 to 6, wherein the hollow tube is a steel pipe.

Images