JP2012127581A - Method of building pipe member for underground heat exchanger in borehole of ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate build of a pipe member into a target depth without using a large-scale auxiliary member such as a balance weight when the pipe member whose specific gravity is smaller than liquid is lowered and built along its pipe axis direction, into a borehole filled with liquid.SOLUTION: The method is related to lowering and build of the pipe member of an underground heat exchanger, whose specific gravity is smaller than the liquid, along the pipe axis direction of the pipe member, into the borehole filled with the liquid. By extracting the liquid in the borehole by a predetermined quantity during build of the pipe member, the level of the liquid is lowered.

Description

  The present invention relates to a method for installing a pipe member used in a ground heat exchanger into a ground excavation hole.

  A geothermal heat utilization system that heats and cools buildings using geothermal heat with small year-round temperature fluctuations is attracting attention. In this geothermal heat utilization system, a geothermal heat exchanger is installed in the ground to collect and radiate heat with the ground. For example, heat is dissipated to the ground in summer and heat is collected from the ground in winter.

  This underground heat exchanger has a pipe member embedded vertically in the ground. Then, the heat medium is poured into the pipe member, and the heat medium is taken out after exchanging heat with the underground heat, and sent to the heat pump for use.

Such an underground heat exchanger is installed in the ground as follows, for example.
First, an excavation hole is formed in the ground by an excavator such as a boring machine or an auger. Then, the pipe member is built (inserted) into the excavation hole from above along the pipe axis direction, and then the gap between the excavation hole and the pipe member is backfilled with an appropriate filler.

  Here, the drilling water is usually used for the above-described excavation, and therefore, the drilling hole is filled with the drilling water at the time of construction after excavation. Recently, a resin pipe is used as the pipe member, and the resin pipe has a specific gravity smaller than that of water. Therefore, when the pipe member is set in the excavation hole along the pipe axis direction from below, the buoyancy based on the specific gravity difference with the drilling water acts on the pipe member and floats. It was difficult to build up to the target building depth.

  In this regard, Patent Document 1 describes that a balance weight is used as an auxiliary member in order to make it easy to build up to a target building depth. In other words, it is disclosed that a buoyancy acting on the pipe member at the time of installation is countered by attaching a balance weight to the pipe member.

JP-A-8-29079

  However, the preparation and attachment of the auxiliary member as the balance weight takes time and can lead to a long construction period and an increase in cost.

  The present invention has been made in view of the above-described conventional problems, and its main purpose is to provide a pipe member having a specific gravity smaller than that of a liquid in a drilling hole containing a liquid such as drilling water. It is to make it easy to install the pipe member to the target installation depth without using a large auxiliary member such as a balance weight when building by sinking along the pipe axis direction.

In order to achieve this object, the invention shown in claim 1
A method in which a pipe member having a specific gravity smaller than that of the liquid is set in the borehole containing the liquid by sinking along the pipe axis direction of the pipe member,
During the installation of the pipe member, the liquid level of the liquid is lowered by removing a predetermined amount of liquid in the excavation hole.

  According to the first aspect of the present invention, the liquid level is lowered. And by this liquid level drop, the length of the portion of the tube member submerged in the liquid is relatively reduced, the buoyancy is reduced, and the length of the portion of the tube member not submerged is relatively Increase. Then, the pipe member is submerged in water until the weight and buoyancy of the portion of the pipe member not submerged are balanced. That is, the pipe member sinks in the excavation hole, and as a result, the pipe member can be easily built up to a target embedment depth.

The invention according to claim 2 is a method of laying a pipe member according to the underground heat exchanger in the excavation hole of the ground according to claim 1,
The pipe member is built by being settled in the excavation hole in a state where liquid is contained in the pipe.

  According to the second aspect of the present invention, the pipe member is not easily affected by the buoyancy caused by the air in the pipe, and therefore, the pipe member is further easily built up to the target build-in depth.

The invention according to claim 3 is a method of erection of the pipe member according to the underground heat exchanger in the ground excavation hole according to claim 1 or 2,
The lowering of the liquid level is repeatedly performed until the embedment depth of the pipe member reaches a target embedment depth.

  According to the third aspect of the invention, the liquid level is repeatedly lowered. Each time the liquid level is lowered, the pipe member sinks in the borehole. Therefore, it is possible to reliably build up to the target building depth.

  According to the present invention, when a pipe member having a specific gravity smaller than that of a liquid is set in the borehole containing liquid such as drilling water, the balance weight or the like is set. Without using a large auxiliary member, it becomes easy to install the pipe member to the target installation depth.

It is explanatory drawing of the underground heat utilization system 11 using the underground heat exchanger 21 which concerns on this embodiment. 2A is a side view of the underground heat exchanger 21 seen through the hole 23 of the ground G, and FIG. 2B is a cross-sectional view taken along line BB in FIG. 2A. 3A and 3B are explanatory diagrams of the construction procedure of the installation work of the underground heat exchanger 21. FIG. 4A to 4C are explanatory diagrams of the construction procedure. 5A to 5C are explanatory diagrams of the construction procedure. 6A is an explanatory diagram of the state of the early stage of erection, FIG. 6B is an explanatory diagram of the state of the erection end, and FIG. It is explanatory drawing and FIG. 6D is a figure which shows that further embedment becomes possible by the same water level fall.

=== This Embodiment ===
<<< About the underground heat exchanger 21 >>>
FIG. 1 is an explanatory diagram of a ground heat utilization system 11 using a ground heat exchanger 21 according to the present embodiment. 2A is a side view of the underground heat exchanger 21 seen through the hole 23 of the ground G, and FIG. 2B is a cross-sectional view taken along line BB in FIG. 2A.

  The ground heat utilization system 11 is for heating the building 1 by using heat from the ground heat exchanger 21 that performs heat exchange with the ground G and the heat medium 26 of the ground heat exchanger 21. A heat pump 15 that generates hot water and cold water for cooling, and a circulation pump 17. In addition, since the structure of the heat pump 15 is known, the description is abbreviate | omitted.

  As shown in FIGS. 2A and 2B, the underground heat exchanger 21 is a so-called “borehole system”. That is, the filling material filled in the space SP23 between the borehole 23 and the U-shaped pipe 30 and the U-shaped pipe 30 inserted into the borehole 23, and the space SP23 between the borehole 23 and the U-shaped pipe 30. 27. Then, water or antifreeze or the like is sent as heat medium 26 from the heat pump 15 to one pipe end opening 35 a of the U-shaped pipe 30, and the heat medium 26 flows into the ground G while flowing through the U-shaped pipe 30. Heated or cooled by heat, and then sent from the other pipe end opening 35 b of the U-shaped pipe 30 toward the heat pump 15 by the circulation pump 17, and used for hot water generation or cold water generation by the heat pump 15.

  The hole 23 is a hole excavated almost perpendicularly to the ground G by an excavator such as a boring machine or an auger, and has a diameter of 100 to 200 mm and a depth of 30 to 150 m.

  The U-shaped tube 30 is a U-shaped tube made of resin such as high-density polyethylene. Specifically, the U-shaped tube 30 includes a U-shaped joint portion 31 that forms a folded portion of the flow path of the heat medium 26, and two single tubes 35 and 35 that are connected to the U-shaped joint portion 31. The pipe end openings 35 a and 35 b of the two single pipes 35 and 35 are respectively protruded from the hole 23 while the U-shaped joint part 31 is positioned at the deepest part of the hole 23. One of the tube end openings 35a and 35b serves as an intake port for the heat medium 26 sent from the heat pump 15, and the other 35b sends the heat medium 26 exchanged with the ground G to the heat pump 15. It becomes a delivery exit.

  In the illustrated example, a pair of such U-shaped tubes 30, 30 are provided for each fistula 23. In other words, in FIG. 2A, the pair of U-shaped tubes 30, 30 are built in the fistula 23 with the U-shaped joint portions 31, 31 at the leading ends being overlapped, although they are hidden behind and cannot be seen. Thus, as shown in FIG. 2B, a total of four single tubes 35, 35, 35, 35 are arranged. Therefore, in this embodiment, a group of a pair of U-shaped pipes 30 and 30 corresponds to a “pipe member” according to the claims. However, the number of U-shaped tubes 30 is not limited to a pair, and may be one. Incidentally, in the case of providing a pair of U-shaped tubes 30 and 30, considering the insertability into the fist hole 23 at the time of erection, the U-shaped joint portions 31 and 31 may be fixed by shifting each other up and down. If it does in this way, the size of the part which becomes the head at the time of erection in these U-shaped pipes 30 and 30 will become small, and it will become easy to erection into the fistula 23.

  The filler 27 is made of, for example, mortar, river sand, mountain sand, quartz sand, or the like as a base material, and is densely filled into the space SP23 between the U-shaped tube 30 and the fistula 23. Thereby, heat exchange is performed between the heat medium 26 in the U-shaped tube 30 and the ground G through the filler 27. In order to increase the heat exchange efficiency, silicon carbide, alumina, and blast furnace with a volume content of 1 to 20% with respect to the filler 27 (= total volume of long particles / total volume of the filler 27). You may mix the long grain thing which consists of at least any 1 type of slag.

<<< About installation work of underground heat exchanger 21 >>>
3A to 5C are explanatory diagrams of the construction procedure of the installation work of the underground heat exchanger 21. FIG. 3A to 5C, a part of the configuration is shown in a side view, and the other configuration is shown in a vertical sectional view. In addition, hatching is omitted for some cross-sectional portions for the purpose of preventing complication of the drawing.

  First, as shown in FIG. 3A, a resin pipe 22 made of vinyl chloride or the like for retaining earth is driven into the target ground G while the pipe axis direction is directed in the vertical direction. The resin tube 22 prevents the ground surface layer from collapsing, and the length thereof is, for example, a short one of 1 to 5 m. However, with respect to the tube diameter, since the above-described pores 23 are formed on the inner peripheral side thereof, the inner diameter of the resin tube 22 is set slightly larger than the diameter of the pores 23.

  Next, as shown in FIG. 3B, by excavating the portion of the ground G inside the resin tube 22, a hole 23 having a hole diameter of 100 to 200 mm and a depth of 30 to 150 m as shown in FIG. 4A is finally formed. To do. This excavation is performed by an excavating machine such as a boring machine or an auger. For the purpose of protecting the hole wall or drilling itself, the excavator 23 has the same size as the excavator 23 at the same time or immediately after the excavation. A matching casing steel pipe 24 is inserted. The casing steel pipe 24 may be omitted. Further, in the inside of the borehole 23 (to be exact, it should be referred to as “inside of the casing steel pipe 24”, but in the following, the borehole 23 including the casing steel pipe 24 will be simply referred to as the borehole 23). Water 23w is full. This drilling water 23w is used at the time of excavation. In other words, the drilling water 23w is pumped toward the lower side of the borehole 23 at the time of excavation. It is used to perform excavation itself by being injected at a high pressure on the excavation surface. Therefore, at the end of excavation, the borehole 23 is generally filled with the used drilling water 23w.

  Then, as shown in FIG. 4B and FIG. 4C, the U-shaped tubes 30 and 30 are arranged in the tube axis direction (the tube axis direction of the single tube 35) in the hole 23 filled with the drilling water 23 w. Installed with the longitudinal direction of the barrel settling down along the vertical direction.

  Specifically, first, the U-shaped tube 30 is carried in the field with the coil wound up. In this example, since the pair of U-shaped tubes 30 and 30 are built in the fistula 23 as described above, a pair of U-shaped tubes 30r and 30r wound in a coil shape are also carried in the field, and the ground It is attached to a pair of reel devices 70 and 70 placed directly on G. Each reel device 70 rotates the U-shaped tube 30r in the same winding state horizontally and feeds it. Then, the fed U-shaped tube 30 is pulled up to a predetermined height by a pulling mechanism 80 disposed above the hole 23 and then enters the hole 23 in a state where it is suspended just above the hole 23. It is built sequentially by following the built-in route of going.

  During this erection, the drilling water 23w in the pit 23 is the upper edge of the mouth 23eu of the pit 23 by the volume of the U-shaped tubes 30 and 30 built in the pit 23. It naturally overflows from the section 23eu and is drained. Therefore, almost always, the mouth portion 23eu of the hole 23 is filled with the drilling water 23w.

  Further, when the lower end portion 30d of the U-shaped tube 30 is installed, the U-shaped joint portions 31, 31 of the pair of U-shaped tubes 30, 30 are overlapped with each other and bound together with an appropriate binding tool such as a number wire. After fixing, it is inserted together into the mouth 23eu of the fistula 23. Therefore, after that, the pair of reel devices 70 and 70 are interlocked with each other, and the U-shaped tubes 30 and 30 that are in charge of the reel devices 70 and 30 are fed out while aligning the feeding amounts.

  By the way, during this erection, water is passed into the U-shaped tubes 30 and 30. That is, at least a portion of the U-shaped tube 30 built in the fistula 23 is filled with water. The reason for this is that the buoyancy due to the air in the U-shaped tubes 30 and 30 is eliminated by eliminating the air in the tube, and the U-shaped tubes 30 and 30 are submerged in the drilling water 23w. It is for performing smoothly.

However, even if the influence of the buoyancy due to the air in the pipe is eliminated, the buoyancy due to the specific gravity difference with the drilling water 23w is acting on the U-shaped tubes 30 and 30. That is, the density of the drilling water 23w is about 1 kg / m ³ , and the density of the U-shaped tube 30 is 0.93 to 0.96 kg / m ³ , so that the specific gravity of the U-shaped tube 30 is the drilling water. Due to being smaller than 23 w, the buoyancy Ff based on this specific gravity difference acts on the U-shaped tubes 30 and 30.

  Here, the buoyancy Ff caused by the specific gravity difference is very small and hardly affects the erection since the erection depth Lt is not deep in the early stage of erection as shown in FIG. 6A. Specifically, since the buoyancy Ff is smaller than the weight of the portions 30s, 30s (FIG. 4B) of the U-shaped tubes 30, 30 that are substantially suspended from the lifting mechanism 80, basically, the U-shaped tubes 30, 30 are used. If it is sent out from the pulling mechanism 80, it will sink into the hole 23 sequentially by the amount sent out.

  However, at the end of the erection as shown in FIG. 6B, the U-shaped tubes 30 and 30 may not settle further no matter how much the lifting mechanism 80 is sent out. This is because the buoyancy Ff and the weights of the portions 30 s and 30 s of the U-shaped tubes 30 and 30 are substantially balanced. When this balanced state occurs before reaching the target erection depth Lta in FIG. 6D, as shown in FIG. 6B, further erection is impossible, that is, the U-shaped tubes 30, 30 Cannot be built up to the target build-up depth Lta.

  Therefore, in this embodiment, when this balanced state is reached, the drilling water 23w is extracted from the borehole 23 by a predetermined amount by using a drainage pump, an air blower or the like (not shown), and the water level is lowered. ing. That is, the state shown in FIG. 6B is changed to the state shown in FIG. 6C.

  Then, due to this lowering of the water level, the lengths of the portions 30wd and 30wd of the U-shaped tubes 30 and 30 that are submerged are relatively reduced and the buoyancy is reduced, and the portions of the U-shaped tubes 30 and 30 that are not submerged. Since the lengths of 30 wu and 30 wu are relatively increased, the state of FIG. 6C is changed to the state of FIG. The tube 30, 30 is immersed in water. That is, the U-shaped tubes 30 and 30 settle in the fistula 23, and as a result, the U-shaped tubes 30 and 30 can be easily built up to the target building depth Lta.

  Furthermore, in this embodiment, by extracting the predetermined amount of the drilling water 23w, the water level is calculated from the starting position of the erection depth Lt (in this example, the upper edge 23eu which is the mouth of the fist hole 23). Is set to be lower than the predetermined length Lw, so that the erection depth Lt that achieves the balanced state is equal to or deeper than the target erection depth Lta. As a result, after that, the above-mentioned balanced state does not appear again before reaching the target embedment depth Lta, so that the U-shaped tubes 30 and 30 can be connected to the target as shown in FIG. 6D. It is possible to build up to the build-up depth Lta.

  However, if, for some reason, the above-mentioned balanced state is entered again and the construction becomes impossible, the hole water 23w may be extracted once again to lower the water level. Then, again, the U-shaped tubes 30 and 30 start to settle based on the above-described mechanism. That is, the water level reduction due to the extraction of the drilling water 23w is not limited to once, and may be repeated a plurality of times until the U-shaped tubes 30 and 30 reach the target built-in depth Lta.

  The predetermined length Lw changes according to the target embedding depth Lta, specific gravity difference, and the like, and the calculation method will be described later. Further, the starting position of the above-described erection depth Lt is generally the upper edge 23eu which is the mouth 23eu of the fistula 23, as in the example of FIG. 6C. What is the erection depth Lt? Specifically, it refers to the depth at which the U-shaped joint portion 31 which is the lower end portion 30d of the U-shaped tube 30 is located.

  When the target erection depth Lta is reached in this way (FIG. 4C), the U-tubes 30 are then cut to separate the U-tubes 30 from the reel devices 70. As a result, as shown in FIG. 5A, upper end portions 30u (35a) and 30u (35b) of the U-shaped tube 30 are formed, and both tube end openings 35a in the U-shaped tube 30 serving as the upper end portions 30u and 30u. , 35b protrudes upward from the mouth 23eu of the hole 23.

  Next, when the casing steel pipe 24 is inserted as shown in FIG. 5A, the casing steel pipe 24 is pulled upward as shown in FIG. 5B, and the steel pipe 24 is taken out from the bore hole 23. When the steel pipe 24 is pulled out, the upper end portions 30u, 30u... Of the U-shaped pipes 30 and 30 may come into contact with the inner peripheral surface of the casing steel pipe 24 and may be damaged. Therefore, before this extraction, as shown in FIG. 5A, the upper end portions 30u, 30u... Of the U-shaped tubes 30, 30 are covered with a protective cap 90.

  The protective cap 90 has a cylindrical portion 90a as a main body. The outer diameter of the cylindrical portion 90a is smaller than the inner diameter of the casing steel tube 24, and the inner diameter of the cylindrical portion 90a is a total of four upper end portions 30u, 30u,. It is set to a size that can be accommodated together. The cylindrical portion 90a is a covered cylindrical body having a lid portion 90b. When the lid portion 90b is placed on the upper end portions 30u, 30u,. Further, the protective cap 90 is made of a metal such as stainless steel having a certain weight.

  Therefore, as shown in FIG. 5B, there is no significant interference with the casing steel pipe 24 drawn upward, and the protective cap 90 is surely secured to the upper ends 30u, 30u,. As a result, the upper ends 30u of the U-shaped tubes 30, 30 are effectively prevented from being damaged.

  When the casing steel pipe 24 is pulled out, finally, as shown in FIG. 5C, a filler 27 is inserted into the hole 23 to fill the U-shaped pipes 30 and 30, thereby providing a ground heat exchanger. 21 installation work is completed.

  For example, a funnel 95 can be used as a method for putting the filler 27. In this case, the upper caps 30u, 30u,... Of the U-shaped tubes 30, 30 are covered with the protective cap 90 described above. Leave it alone. That is, the funnel 95 is disposed so that the substantially cylindrical portion 95p at the lower end portion of the funnel 95 enters between the inner peripheral surface of the stoma 23 and the outer peripheral surface of the protective cap 90. At this time, the funnel 95 is arranged so that a clearance is formed between the inner peripheral surface of the substantially cylindrical portion 95p which is the lower end portion of the funnel 95 and the outer peripheral surface of the protective cap 90.

  Then, the hopper 98 storing the filler 27 is lifted above the funnel 95 with a mini crane 99 or the like, and the lower end opening 98a of the hopper 98 is opened in that state. Then, the filler 27 falls on the funnel 95. These dropped fillers 27 are guided to the center of the plane while sliding down on the funnel 95, and the substantially cylindrical portion 95p at the lower end of the funnel 95 is introduced. Through the clearance between the protective cap 90 and the protective cap 90. As a result, the filler 27 is filled in the fist hole 23 and the U-shaped tubes 30 and 30 are embedded. At this time, the filler 27 falling from the hopper 98 directly hits the protective cap 90, but this protects the upper ends 30u, 30u... Of the U-shaped tubes 30, 30 from collision of the filler 27. The upper end portions 30u, 30u, ... are reliably prevented from being damaged.

<<< Regarding the Calculation Method of the Predetermined Length Lw According to the Water Level Reduction of the Drilling Water 23w >>>
In the above description, during the erection, the water level of the drilling water 23w is lower than the starting position of the erection depth Lt by a predetermined length Lw, and thereby the buoyancy caused by the specific gravity difference and the U-shaped tube 30 , 30 has been described that the built-in depth Lt that is in a balanced state is equal to or deeper than the target built-in depth Lta. Hereinafter, the calculation method of the predetermined length Lw will be described. explain.

First, regarding the size of the buoyancy acting at the time of erection, if the buoyancy due to the air in the pipes 30 and 30 is ignored, as described above, the other buoyancy to be considered is the drilling water 23w. And the buoyancy Ff based on the specific gravity difference between the U-shaped tube 30 and the magnitude of the buoyancy Ff can be expressed by the following formula 1.
Ff (kg) = (Dw−Du) × (π × (φ2 / 2) ² −π × (φ1 / 2) ² ) × Lt × 4 (1)
In the above equation 1, φ1 and φ2 are the inner / outer diameter (m) of the single tube 35 of the U-shaped tube 30, Lt is the built-in depth (m), and Dw and Du are the cutting depths. It is the density (kg / m ³ ) of the pore water 23w and the U-shaped tube 30. Moreover, the meaning of the numerical value “4” at the end of the right side is that a pair of U-shaped tubes 30 and 30 are provided, thereby having four single tubes 35, 35, 35 and 35.

Here, for the purpose of making it easier to understand, the numerical value of the standard specification of the underground heat exchanger 21 is substituted into the above equation 1. In addition, as a numerical value of this standard specification, the following is mentioned, for example. The inner / outer diameter of the single pipe 35 of the U-shaped pipe 30 is 27/34 mm, the target embedment depth Lta is 100 m, the density Dw of the drilling water 23 w is 1000 kg / m ³ , and the U-shaped pipe The density Du of 30 is 954 kg / m ³ . When these numerical values are substituted into the above equation 1, the following equation is obtained. As a result, it is understood that 6.2 kg of buoyancy Ff acts before reaching the target erection depth Lta.
Ff = (1000−954) × (π × (0.034 / 2) ² −π × (0.027 / 2) ² ) × 100 × 4
= 6.2kg
Therefore, the U-shaped pipes 30 and 30 are in a balance state incapable of being built at a position shifted upward from the target building depth Lta by the buoyancy Ff of 6.2 kg. The penetration depth Lta cannot be reached.

  Here, by lowering the water level with respect to the state of FIG. 6B, as shown in FIG. 6C, by moving the water level of the drilling water 23w downward from the starting position of the erection depth Lt, The weights of the portions 30g and 30g of the U-shaped tubes 30 and 30 coming out into the air are a new force (hereinafter also referred to as a settling force) for sinking the U-shaped tubes 30 and 30 against the buoyancy Ff. Become. Then, until the weights of the portions 30g and 30g and the buoyancy Ff are balanced, the U-shaped tubes 30 and 30 are submerged in water as shown in FIG. 6D. Therefore, the length of the U-shaped tubes 30 and 30 corresponding to the weight corresponding to the buoyancy Ff corresponds to the predetermined length Lw.

Therefore, when the weight of the U-shaped tubes 30 and 30 per unit length is UWu, the predetermined length Lw is calculated by the following equation 2.
Lw = Ff / UWu (2)
Here, as described above, Ff is 6,2 kg, and the weight UWu of the U-shaped tubes 30, 30 per unit length is 2.56 kg / m (= (π × (34/2) ² Since −π × (27/2) ² ) × 954 × 2), when these are substituted into the above equation 2, the predetermined length Lw in this example is 2.4 m (= 6.2 / 2.56). By the way, the meaning of “2” at the end of the formula for calculating the weight UWu is because the U-shaped tubes 30 and 30 are provided as a pair.

=== Other Embodiments ===
As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, The deformation | transformation as shown below is possible in the range which does not deviate from the summary.

  In the above-described embodiment, the water level reduction as the liquid level reduction is performed when a balance state in which the water level cannot be built during the erection is reached, but the execution timing is not limited to this. For example, it may be performed at a time before the installation becomes impossible. However, in that case, the drilling water 23w is extracted in such a water amount that the water level is further lowered than the predetermined length Lw. In other words, this amount of water counters the buoyancy from the drilling water 23w from the actual erection depth Lt (corresponding to a predetermined depth) at the above time point to the target erection depth. However, the amount is set so as to settle based on the weight of the U-shaped tubes 30 and 30.

In the embodiment described above, the pair of U-shaped tubes 30 and 30 made of resin is illustrated as an example of a tube member having a specific gravity smaller than that of water, but the tube shape is not limited to a U shape.
For example, in the case of a double pipe type underground heat exchanger, an outer cylinder and an inner cylinder inserted and arranged in the outer cylinder are used as the main body of the heat exchanger, and the outer cylinder is A single tubular tube member whose bottom end is hermetically sealed is built in the fistula, but if the specific gravity is smaller than water, the present invention is applicable to the single tubular tube member. It is possible to apply the building method related to.
In addition, as an example of this single tubular pipe member, a corrugated pipe (corrugated pipe) is cited, and according to the pipe, due to the effect of expanding the surface area based on the helical corrugated shape of the outer peripheral surface and the inner peripheral surface. The heat exchange efficiency between the ground G and the heat medium in the corrugated pipe can be increased.

  In the above-described embodiment, the drilling water 23w is exemplified as the “liquid” that has entered the borehole 23 that is a drilling hole, but the present invention is not limited to this. For example, when the excavation hole 23 is excavated without using the drilling water 23w, even if the water has entered the excavation hole 23 due to ground water, rain water, or the like, if it is in the excavation hole 23, it is claimed It corresponds to the “liquid” described in 1. That is, before the pipe member such as the U-shaped pipe 30 having a specific gravity smaller than that of the liquid is built in the excavation hole 23, the liquid contained in the excavation hole 23 is completely covered and corresponds to the “liquid” according to the claims. To do.

  In the above-described embodiment, in order to eliminate the influence of the buoyancy caused by the air in the pipe applied from the drilling water 23w to the U-shaped pipe 30 when the digging hole 23 is built in the borehole 23, Although water was added as a liquid, it is not limited to this. For example, when the antifreeze liquid is used as the heat medium 26 flowing in the U-shaped tube 30 during the operation of the underground heat exchanger 21, the antifreeze liquid may be put in the U-shaped tube 30.

1 building, 11 geothermal heat utilization system, 15 heat pump,
17 circulation pump, 21 underground heat exchanger, 22 resin pipe,
23 hole (drilling hole), 23eu mouth (upper edge),
23w drilling water (liquid), 24 casing steel pipe, 26 heat medium,
27 Filler, 30 U-shaped tube (tube member), 30u upper end, 30d lower end,
30g part, 30s part, 30r U-shaped pipe (pipe member) in a wound state,
30wd U-tube part submerged, 30wu U-tube part not submerged,
31 U-shaped joint part, 35 single pipe, 35a pipe end opening, 35b pipe end opening,
70 reel device, 80 lifting mechanism, 90 protective cap,
90a cylindrical part, 90b lid part, 95 funnel, 95p substantially cylindrical part,
98 Hopper, 98a Lower end opening, 99 Mini crane SP23 Space, G Ground (ground), Ff Buoyancy

Claims (3)

A method in which a pipe member having a specific gravity smaller than that of the liquid is set in the borehole containing the liquid by sinking along the pipe axis direction of the pipe member,
The pipe according to the underground heat exchanger to the ground excavation hole, wherein the liquid level of the liquid is lowered by removing a predetermined amount of liquid in the excavation hole during the installation of the pipe member. How to build components. A method for building a pipe member according to the underground heat exchanger into a ground excavation hole according to claim 1,
The tube member is installed in a ground excavation hole in a ground heat exchanger, wherein the tube member is settled and built in the excavation hole in a state where liquid is contained in the tube. A method for building a pipe member according to an underground heat exchanger into a ground excavation hole according to claim 1 or 2,
The construction of the pipe member according to the underground heat exchanger in the ground excavation hole is characterized by repeatedly reducing the liquid level until the construction depth of the pipe member reaches a target construction depth. Method.