JP7545721B2 - Wooden Pile Unit - Google Patents

Description

The present invention relates to wooden piles used for ground improvement, and in particular to wooden pile units formed by bundling multiple wooden piles together.

Wooden piles, concrete piles, steel piles, etc. are used for pile foundations in ground improvement work. Of these, wooden piles are often suitable for use on soft ground with a high moisture content. Wooden piles can reduce the surrounding moisture content while maintaining sufficient bearing capacity. There are also various other benefits, such as the ability to maintain durability for a very long period of time if there is sufficient moisture, and the ability to reduce the effort and cost of construction. Furthermore, it is also possible to reduce carbon dioxide emissions.

A technology that uses such wooden piles is disclosed in Patent Document 1. The technology shown in Patent Document 1 is a carbon stocking method in which wooden piles for carbon stocking, equipped with drainage means, are driven into the ground, and drainage channels are formed on the sides of the logs. In particular, Figures 11 and 12 of Patent Document 1 disclose a structure in which multiple logs are bundled together and a conical bottom cap is attached to the tip.

On the other hand, patent documents 2 to 4 disclose techniques for effectively utilizing geothermal energy using piles in ground improvement. The technique shown in patent document 2 comprises a heat pump unit having a heat exchanger of a heat pump for air conditioning the interior of a building, a heat collection pile buried in the ground, an antifreeze pipe that passes through the heat exchanger and the heat collection pile, antifreeze filled in the antifreeze pipe, and a pump for circulating the antifreeze in the antifreeze pipe, and the heat pump unit is installed in the underfloor space of a building in a geothermal heat pump system that exchanges heat between the ground and the indoor air through circulation.

The technology shown in Patent Document 3 relates to a screw-in type geothermal steel pipe pile in which the heat exchange pipes that make up the geothermal heat exchanger can be set in advance on the pile, and by expanding the diameter of the pile head of the winged steel pipe pile, a structure that balances horizontal and vertical forces and has good penetration performance is achieved. The pile is made up of a lower pile with wings attached to its tip or nearby, and an upper pile that is larger in diameter than the lower pile and is joined integrally to the lower pile via a joining member, and has an expanded head screw-in type steel pipe pile that is buried in the ground by applying a rotational force, and a heat exchange pipe is installed inside the upper pile.

The technology shown in Patent Document 4 is a geothermal heating and cooling system that uses geothermal heat obtained from a heat exchange unit buried underground to cool or heat living spaces. The heat exchange unit is configured by inserting a return pipe with both ends protruding upward from a hollow steel pipe pile that is driven into the ground from the foundation of the building into the hollow steel pipe pile, and storing a heat exchange liquid consisting of an alkaline aqueous solution between the hollow steel pipe pile and the return pipe. One end of the return pipe is connected to an air supply pipe to the living space, and the other end of the return pipe is connected to an air recovery pipe from the living space.

JP 2007-205068 A JP 2012-47360 A JP 2005-188865 A JP 2013-148277 A

Patent Document 1 discloses a structure in which multiple wooden stakes are bundled together to form a unit, but because the tip is machined into a cone shape, there is an issue that machining each individual wooden stake is time-consuming.

The technology shown in Patent Document 2 utilizes geothermal energy using heat collection piles and antifreeze pipes, but when burying them underground, the shape and configuration of the heat collection piles and antifreeze pipes are extremely important. In other words, it is extremely important to determine how to arrange and configure the heat transfer through the antifreeze pipes to effectively utilize geothermal energy while maintaining the basic function of the heat collection piles, but Patent Document 2 does not disclose the specific configurations for these.

Patent Documents 3 and 4 specifically disclose the configuration of steel pipes and heat exchange pipes to be buried underground, but because they both use steel pipes, the construction work is large-scale and very costly. In addition, the technologies described in both documents have in common the need to finely process the steel pipes, which is a labor-intensive task.

The present invention has been made to solve the above problems, and aims to provide a wooden pile unit that can increase the bearing capacity by unitizing multiple wooden piles with simple processing, and that can effectively obtain geothermal energy by using the unitized wooden piles.

The wooden pile unit of the present invention is a wooden pile unit consisting of a bundle of multiple wooden piles used for ground improvement, and is provided with multiple individual wooden piles that are arranged at the tip end at an angle of less than 90 degrees to the longitudinal direction of the wooden piles, and the multiple individual wooden piles are bundled together with the side portion that is the longest in the longitudinal direction of the individual wooden piles facing toward the center.

In this way, the wooden pile unit of the present invention is a wooden pile unit consisting of a plurality of wooden piles used for ground improvement, and includes a plurality of individual wooden piles that cross at an angle of less than 90 degrees to the longitudinal direction of the wooden piles at their tip portions, and the plurality of individual wooden piles are bundled together with the side portion that is the longest in the longitudinal direction of the individual wooden piles facing toward the center. This simplifies the processing of the individual wooden piles by only crossing the tip portions in one direction at a predetermined angle, and has the effect of enabling the bundled wooden piles to firmly support buildings on the ground.

In particular, bundling multiple individual wooden piles creates a supporting force between them, suppressing eccentricity when burying them in the ground and allowing them to move in a straight line with a stable direction, making it possible to bury the wooden pile unit in a precise position and with a precise posture. In addition, bundling multiple individual wooden piles means that the side shape of the areas where the individual wooden piles are in contact with each other and the surrounding areas is not flat in the horizontal direction but has an uneven shape, which increases the friction with the soil in the horizontal direction and makes it possible to stably support structures on the ground. Furthermore, even when multiple individual wooden piles are bundled together, they are tapered toward the center of the tip, so the increased lateral earth pressure allows them to be buried smoothly in the ground.

The wooden pile unit of the present invention is, as necessary, a structure in which at least three or more individual wooden piles are bundled together in contact with adjacent individual wooden piles to form a void area in the center, and a hollow heat exchange pipe is stored in a U-shape in the void area, with the openings at both ends of the heat exchange pipe exposed from the top of the void area.

In this way, in the wooden pile unit of the present invention, at least three or more individual wooden piles are bundled together while in contact with adjacent individual wooden piles to form a void area in the center, and a hollow heat exchange pipe is stored in a U-shape in the void area, with the openings at both ends of the heat exchange pipe exposed from the top of the void area. This has the effect of making it possible to extract geothermal energy with a very simple structure by utilizing the space in the center that is created when three or more individual wooden piles are restrained.

In the wooden pile unit according to the present invention, as necessary, the side portion of each individual wooden pile that is the longest in the longitudinal direction is processed into a flat shape, and a gap area is formed by the side portion including the flat surface of each individual wooden pile.

In this way, in the wooden pile unit of the present invention, the side portion of each individual wooden pile that is the longest in the longitudinal direction is processed into a flat shape, and a void area is formed by the side portion including the flat surface of each individual wooden pile, which has the effect of expanding the volume of the void area and enabling efficient heat exchange with a thick heat exchange pipe.

The wooden pile unit of the present invention is provided with a restraining means, if necessary, which is attached to the outer periphery of the side of the assembly of a plurality of individual wooden piles arranged in contact with each other, and which holds the assembly of individual wooden piles together, and a hollow heat exchange pipe is stored in a U-shape in the gap area created between the outer surface of the individual wooden piles and the restraining means, and the openings at both ends of the heat exchange pipe are arranged in a state where they are exposed from the gap area.

In this way, the wooden pile unit of the present invention is provided with a restraining means that is attached to the outer periphery of the side of the aggregate of a plurality of individual wooden piles that are arranged in contact with each other and that holds the aggregate of the individual wooden piles together, and a hollow heat exchange pipe is stored in a U-shape in the gap area that is created between the outer surfaces of the individual wooden piles and the restraining means, and the openings at both ends of the heat exchange pipe are arranged in a state where they are exposed from the gap area, thereby achieving the effect of being able to extract geothermal energy with a very simple structure by utilizing the space created between the outer surfaces of the individual wooden piles and the restraining means.

FIG. 2 is a six-view diagram showing the structure of each individual wooden pile constituting the wooden pile unit according to the first embodiment. FIG. 2 is an overall perspective view of the wooden pile unit according to the first embodiment. FIG. 2 is a six-sided view showing the structure of the wooden pile unit according to the first embodiment. FIG. 11 is an overall perspective view of a wooden pile unit according to a second embodiment. FIG. 11 is a cross-sectional view of a wooden pile unit according to a second embodiment. FIG. 11 is a top view of the wooden pile unit according to the second embodiment. FIG. 13 is a diagram showing the structure of the wooden pile unit according to the second embodiment when a cap is fitted to the tip thereof. FIG. 13 is a top view of the wooden pile unit according to the third embodiment. FIG. 11 is an overall perspective view of a wooden pile unit according to another embodiment. FIG. 11 is a top view of a wooden pile unit according to another embodiment.

(First embodiment of the present invention)
The wooden pile unit according to this embodiment will be described with reference to Figures 1 to 3. The wooden pile unit according to this embodiment firmly supports buildings on the ground by bundling a plurality of wooden piles used for ground improvement into a unit, and also captures geothermal energy by utilizing the gaps generated by bundling the wooden piles.

Wooden piles were not used much for a long time after the war due to environmental destruction caused by deforestation. However, many wooden piles were used before that, and they have supported buildings in the same condition as they were at the time, without corroding for a long time. For this reason, ground improvement using wooden piles has been carried out in recent years. When wooden piles used for ground improvement are buried deeper than the groundwater level, they are always submerged in water, so they will not corrode even without any treatment. When they are buried only shallower than the groundwater level, it is possible to maintain their condition for a long time by carrying out preservative and anti-termite treatments.

1 is a six-sided view showing the structure of an individual wooden pile (hereinafter, referred to as an individual wooden pile) constituting a wooden pile unit according to this embodiment. FIG. 1(A) is a top view of the individual wooden pile, FIG. 1(B) is a bottom view of the individual wooden pile, FIG. 1(C) is a front view of the individual wooden pile, FIG. 1(D) is a rear view of the individual wooden pile, FIG. 1(E) is a right side view of the individual wooden pile, and FIG. 1(F) is a left side view of the individual wooden pile. As shown in FIG. 1, the tip of the individual wooden pile 2 is cut at a predetermined angle α less than 90 degrees with respect to the longitudinal direction A. This cut is made in a single direction from one side portion S1 of the individual wooden pile 2 to the other opposing side portion S2 at a predetermined angle α. More specifically, for example, referring to FIG. 1(C), the blade is inserted from one side portion S1 perpendicular to the longitudinal direction A toward the opposing lower side portion S2, and the blade is moved in a single direction while maintaining the horizontality of the left and right sides.

This type of shape can be formed much more easily than the conventional method of forming the tip into a cone shape, simplifying the work process. Note that in Figure 1, the individual wooden stake 2 is shown in its peeled state.

Figure 2 is an overall perspective view of the wooden pile unit according to this embodiment, and Figure 3 is a six-sided view showing the structure of the wooden pile unit according to this embodiment. The wooden pile unit 1 shown in Figures 2 and 3 is three individual wooden piles 2 (2a, 2b, 2c) shown in Figure 1 that are restrained together by restraining means 3. At this time, the side portion S2 of each individual wooden pile 2, which has the longest longitudinal dimension, is restrained in a state facing the center. In other words, as shown in Figures 2 and 3, the three individual wooden piles 2a, 2b, 2c are gathered together, making the tip center portion of the wooden pile unit 1 sharp, making it easier to drive the wooden pile unit 1 into the ground. In addition, since the bearing force of the three individual wooden piles 2a, 2b, 2c can support a building on the ground, the number of buried wooden piles can be reduced, and processing efficiency can be improved.

The number of individual wooden stakes 2 that can be restrained can be two or more depending on the usage environment. Regardless of the number, the shape of the individual wooden stakes 2 will be the same, and the longest side portion S2 will be restrained toward the center. For example, in the case of two individual wooden stakes 2, the individual wooden stakes 2 will be placed and restrained so that the side portions S2 are in contact with each other.

In this way, the wooden pile unit 1 according to this embodiment has a number of individual wooden piles 2 whose tip portions are arranged at an angle of less than 90 degrees to the longitudinal direction of the wooden pile, and the individual wooden piles 2 are bundled together with the side portion S2, which is the longest length in the longitudinal direction of the individual wooden piles 2, facing toward the center. This simplifies the processing of the individual wooden piles 2 by simply cutting the tip portions in one direction at a specified angle, and allows the bundled individual wooden piles 2 to firmly support buildings on the ground.

In particular, bundling multiple individual wooden piles 2 creates a support force between them, suppressing eccentricity when burying them in the ground and allowing them to move in a straight line with a stable direction, making it possible to bury the wooden pile unit in a precise position and with a precise posture. In addition, bundling multiple individual wooden piles 2 causes the side shape of the areas where the individual wooden piles 2 are in contact with each other and the surrounding areas to have an uneven shape rather than a flat shape in the horizontal direction, which increases the frictional force with the soil in the horizontal direction and makes it possible to stably support structures on the ground. Furthermore, even when multiple individual wooden piles 2 are bundled together, they are tapered toward the center of the tip, which allows them to be buried smoothly in the ground due to the increased lateral earth pressure.

Second Embodiment of the Invention
The wooden pile unit according to this embodiment will be described with reference to Figures 4 to 6. The wooden pile unit 1 according to this embodiment is an extension of the function of the wooden pile unit 1 according to the first embodiment, and utilizes the space created by restraining a plurality of individual wooden piles 2 to extract geothermal energy from the ground in which the wooden pile unit 1 is buried. In this embodiment, since it is necessary to create space by restraining a plurality of individual wooden piles 2, a group of at least three or more individual wooden piles 2 (2a, 2b, 2c) is restrained. Also, in this embodiment, explanations that overlap with those in the first embodiment will be omitted.

Figure 4 is an overall perspective view of the wooden pile unit according to this embodiment, Figure 5 is a cross-sectional view taken along line B-B of the wooden pile unit according to this embodiment, and Figure 6 is a top view of the wooden pile unit 1 according to this embodiment. As shown in the figure, three individual wooden piles 2 (2a, 2b, 2c) are restrained in a state of mutual contact with adjacent individual wooden piles 2, forming a gap area G in the center of the wooden pile unit 1. A cap 4 is attached to the gap area G at the tip side of the wooden pile unit 1 to prevent mud and the like from entering when the wooden pile unit 1 is struck and buried in the ground.

A U-shaped heat exchange pipe 5 is disposed in the gap area G above the cap 4, and both ends 5a, 5b of the pipe are connectable to a heat exchange system (e.g., a heat pump) on the ground. The mechanism of heat pumps is generally known, so a detailed explanation is omitted. The heat exchange pipe 5 is made of a material with high thermal conductivity, such as stainless steel or copper, and the inside of the pipe is filled with antifreeze liquid, which is circulated by a pump or the like.

For example, during the hot summer months, heat from above ground is transported underground via antifreeze, where it is then released into the ground, where the temperature is relatively low. Conversely, during the cold winter months, heat from the underground, which is relatively high, is transported to the ground via antifreeze, where it is then released to heat the ground. In other words, it is possible to maintain a relatively stable temperature throughout the year, making this a very effective system for environments such as plant cultivation.

When the wooden pile unit 1 is buried at a position deeper than the groundwater level, moisture will enter through the gaps between the individual wooden piles 2 (2a, 2b, 2c), causing the heat exchange pipe 5 to be held underwater in the ground, and the heat exchange efficiency can be significantly improved. On the other hand, when the wooden pile unit 1 is buried at a position shallower than the groundwater level and water does not flood into the void area G, for example, water can be stored in a hollow, elongated pipe (hereinafter referred to as an input pipe) with a closed bottom, and the U-shaped heat exchange pipe 5 can be inserted into the input pipe so that both ends are exposed upward, and then installed together with the input pipe in the void area G, thereby maintaining a state similar to that in which the heat exchange pipe 5 is held underwater in the ground. In this case, a very small hole may be drilled in the input pipe so that the moisture is replaced little by little over a long period of time. The replacement moisture may be rainwater, water stored above ground in advance, or supplied from a water pipe.

In the above, heat exchange is performed by circulating antifreeze in the heat exchange pipe 5, but it is also possible to arrange the heat exchange pipe 5 so that it passes through multiple wooden pile units 1, make the heat exchange pipe 5 hollow, take in outside air from an opening on one side, exchange heat while passing through multiple wooden pile units 1, and release the air from an opening on the other end into the building, thereby circulating air and adjusting the temperature.

In the above, the cap 4 is attached to the gap area G at the tip of the wooden pile unit 1, but it is also possible to fill the gap area G with filler beforehand without using the cap 4, and then bury the wooden pile unit by striking it, and then removing the filler from above ground after burying the wooden pile unit, thereby preventing mud and the like from entering the gap area G. In this case, the heat exchange pipe 5 may be inserted to the deepest part of the wooden pile unit 1 that is buried, or it may be inserted to a midpoint. When inserting to a midpoint, filler may be left in the gap area G in order to lock the heat exchange pipe 5, or the heat exchange pipe 5 may be hooked and locked with something like a hook.

Furthermore, as shown in FIG. 7, a cap 4 may be fitted to the tip portion to prevent mud and other foreign matter from entering the gap region G when the tube is buried.

In this way, in the wooden pile unit 1 according to this embodiment, at least three or more individual wooden piles 2 are bundled together while in contact with other adjacent individual wooden piles 2 to form a gap area G in the center, and the hollow heat exchange pipes 5 are stored in a U-shape in the gap area G, with the openings at both ends of the heat exchange pipes 5 exposed from the gap area G. Therefore, by utilizing the space in the center that is created when three or more individual wooden piles 2 are restrained, geothermal energy can be extracted with a very simple structure.

Third embodiment of the present invention
The wooden pile unit according to this embodiment will be described with reference to Fig. 8. Fig. 8 is a top view of the wooden pile unit 1 according to this embodiment. Here, when peeling the bark of the individual wooden pile 2, only one side surface is processed to be flat. That is, in Fig. 8, only one place is cut in the longitudinal direction at the part of the string H to form a flat area on the side surface of the individual wooden pile 2.

With the above-mentioned flat surface formed on the side surface, the tip of the individual wooden pile 2 is cut at a specified angle α to the longitudinal direction A. At that time, the flattened side surface is cut so that it becomes the other side surface portion S2 described above. In this way, the side surface portion that is the longest in the longitudinal direction of the individual wooden pile 2 is processed into a flat surface, and by unitizing each individual wooden pile 2 around its flat surface, a wide gap region G can be formed. By widening the gap region G, it is possible to increase, thicken, or lengthen the heat exchange pipes 5, thereby improving heat exchange efficiency.

When flattening the side surface, the larger the flat area becomes, the less sharp the tip of the individual wooden stake 2 becomes (because the tip becomes flat to match the edge of the flat surface), so it is desirable to process it into a flat area that maintains a certain degree of sharpness.

In addition, although the above description describes flattening when peeling the bark off the individual wooden stakes 2, there is no particular limit to the timing for flattening, and it may be done after sharpening the tip.

In this way, in the wooden pile unit 1 according to this embodiment, the side portion S2, which is the longest in the longitudinal direction of the individual wooden pile 2, is processed into a flat shape, and the side portion including the flat surface of each individual wooden pile 2 forms a gap region G, so that the volume of the gap region can be expanded and heat can be exchanged more efficiently with a thicker or longer heat exchanger pipe 5.

Other Embodiments of the Invention
The wooden pile unit according to this embodiment will be described with reference to Figures 9 and 10. Figure 9 is an overall perspective view of the wooden pile unit according to this embodiment, and Figure 10 is a top view of the wooden pile unit according to this embodiment. Here, two individual wooden piles 2 (2d, 2e) are restrained to form the wooden pile unit 1.

As shown in Figures 9 and 10, the wooden pile unit 1 according to this embodiment is an integrated assembly of two individual wooden piles 2 (2d, 2e) with a sheet-like restraining means 3 attached to the outer periphery of the side surface. In this case, rather than attaching the restraining means 3 individually along the side surface of each individual wooden pile 2, the two individual wooden piles 2 (2d, 2e) are integrated and the restraining means 3 is attached to the outermost periphery, forming a gap region F between the outer surface of the individual wooden pile 2 and the sheet of restraining means 3.

The hollow heat exchange pipes 5 as described above are stored in the void area F in a U-shape, and the openings at both ends of the heat exchange pipes 5 are arranged in a state where they are exposed from the void area F. With this structure, two individual wooden piles 2 can form two void areas F, and the number of heat exchange pipes 5 can be increased accordingly. If three individual wooden piles 2 (2a, 2b, 2c) are used in the structure of this embodiment, it is possible to form a total of four void areas, including the void area G in the center, in addition to the three voids formed by the combinations of two individual wooden piles 2 (three combinations of 2a and 2b, 2a and 2c, and 2b and 2c) and the restraining means 3 (voids formed by each of the three sides of the restraining means 3 that are formed in a roughly triangular shape when viewed from above), and further improving the heat exchange efficiency.

In this way, the wooden pile unit 1 according to this embodiment is equipped with a restraining means 3 that is attached to the outer periphery of the side of the assembly of multiple individual wooden piles 2 that are arranged in contact with each other, and that holds the assembly of individual wooden piles 2 together. A hollow heat exchange pipe 5 is stored in a U-shape in the gap area F that is created between the outer surface of the individual wooden piles 2 and the restraining means 3, and the openings at both ends of the heat exchange pipe 5 are arranged in a state where they are exposed from the gap area F. Therefore, by utilizing the gap area created between the outer surface of the individual wooden piles 2 and the restraining means 3, geothermal energy can be extracted efficiently with a very simple structure.

REFERENCE SIGNS LIST 1 Wooden pile unit 2 (2a, 2b, 2c, 2d, 2e) Individual wooden pile 3 Restraint means 4 Cap 5 Heat exchange pipe F, G Void area S1, S2 Side portion

Claims (3)

A wooden pile unit formed by bundling a plurality of wooden piles used for ground improvement,
The wooden pile is provided with a plurality of individual wooden piles that are arranged at an angle of less than 90 degrees to the longitudinal direction of the wooden pile at the tip portion, and the plurality of individual wooden piles are bundled together with the side portion that is the longest in the longitudinal direction of the individual wooden piles facing toward the center ,
This wooden pile unit is characterized in that at least three or more of the individual wooden piles are bundled together in a state of contact with adjacent individual wooden piles to form a gap area in the center, a hollow heat exchange pipe is stored in a U-shape in the gap area, and the opening portions at both ends of the heat exchange pipe are exposed from the top of the gap area . The wooden pile unit according to claim 1,
A wooden pile unit in which the side portion of each individual wooden pile that is the longest in the longitudinal direction is processed into a flat shape, and the gap area is formed by the side portion including the flat surface of each individual wooden pile . A wooden pile unit formed by bundling a plurality of wooden piles used for ground improvement,
The wooden pile is provided with a plurality of individual wooden piles that are arranged at an angle of less than 90 degrees to the longitudinal direction of the wooden pile at the tip portion, and the plurality of individual wooden piles are bundled together with the side portion that is the longest in the longitudinal direction of the individual wooden piles facing toward the center,
A wooden pile unit comprising: a restraining means attached to the outer periphery of the side of a group of a plurality of individual wooden piles arranged in contact with each other, and which restrains the group of individual wooden piles together; a hollow heat exchange pipe stored in a U-shape in the gap area created between the outer surface of the individual wooden piles and the restraining means; and an opening portion at both ends of the heat exchange pipe arranged so as to be exposed from the gap area .

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