Pile construction method, pile removal method, and pile structure

Abstract

To provide a pile construction method, a pile removal method, and a pile structure that can reduce labor and cost involved in pressing in a casing.SOLUTION: A pile construction method is for constructing a pile structure that will be removed after a predetermined period of time passes. The pile construction method comprises the steps of: forming a drilled hole 2 in the ground 1; erecting a reinforcing bar cage 10 to which a pipe 20 into which replacement material is injected when the pile structure is removed is fixed into the drilled hole 2; and pouring concrete into the drilled hole 2 into which the reinforcing bar cage 10 to which the pipe 20 is fixed is erected to form a concrete portion in which the reinforcing bar cage 10 and the pipe 20 are embedded.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a pile construction method for constructing a pile structure, a pile removal method, and the pile structure. [Background technology]

[0002] Patent Document 1 describes a method for improving ground in a pile extraction hole. In this method, after an existing pile is extracted using the edge cutting and extraction method, volume adjustment sand is poured into the bottom sedimentary soil and muddy water accumulated in the pile extraction hole. Then, a mixer is inserted into the pile extraction hole to mix the volume adjustment sand, and an improved body is filled into the pile extraction hole while the mixer is removed. After that, a backfilling process is carried out in which the space between the top surface of the improved body and the surface of the surrounding ground is filled back with improved soil or the like.

[0003] Patent Document 2 describes a method for removing existing piles. In this method, first, multiple PC steel bars are buried in the head of the existing pile, and a caisson foundation liner plate with a larger cross-sectional area than the existing pile is positioned on the ground surface so that it is concentric with the existing pile. After that, the caisson foundation liner plate is inserted into the ground until its lower end reaches below the height of the head of the existing pile. Then, soil is removed between the existing pile and the caisson foundation liner plate to form a soil removal space, and the soil removal space is filled with liquefied treated soil.

[0004] After the liquefied soil has solidified, a casing with a bit at its lower end is positioned on the ground surface so that it is concentric with the existing pile, and then the casing is inserted into the ground until its lower end reaches the depth of the bottom of the existing pile. Then, soil is dumped from inside the casing to form a soil dumping space, and stabilizing liquid is supplied to the soil dumping space. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2021-169749 A [Patent Document 2] Patent No. 6645098 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned method for removing an existing pile, it is necessary to press a casing into the ground until its lower end reaches the depth of the bottom surface of the existing pile. This casing is provided to protect the hole wall. However, pressing in the casing is currently time-consuming and costly. Therefore, it is required to reduce the time and cost required for pressing in the casing.

[0007] An object of the present disclosure is to provide a pile construction method, a pile removal method, and a pile structure that can reduce the effort and cost involved in pressing in a casing. [Means for solving the problem]

[0008] (1) A pile construction method according to the present disclosure is a pile construction method for constructing a pile structure to be removed after a predetermined period of time has passed. The pile construction method includes the steps of forming a borehole in the ground, erecting a reinforcing bar cage to which a pipe is fixed, into which a replacement material is injected when the pile structure is removed, and pouring concrete into the borehole into which the reinforcing bar cage to which the pipe is fixed is erected, thereby forming a concrete section in which the reinforcing bar cage and the pipe are buried.

[0009] (2) The pile removal method according to the present disclosure is a pile removal method for removing a pile structure constructed by the above-described pile construction method, and includes the steps of: extracting the pile structure from the borehole; and filling the borehole with a replacement material by extracting the pile structure and injecting a replacement material into piping.

[0010] In this pile construction method and pile removal method, a reinforcing bar cage is erected in a borehole formed in the ground, and a pipe into which a replacement material is injected is fixed to the reinforcing bar cage. Concrete is poured into the reinforcing bar cage to which the pipe is fixed, so that the reinforcing bar cage and the pipe are buried in the concrete. Then, when the pile structure is pulled out of the borehole after a predetermined period of time, a replacement material is injected into the pipe fixed to the reinforcing bar cage. The replacement material is injected into the pipe to fill the borehole. By filling the borehole with the replacement material while the pile structure is pulled out, the replacement material protects the wall of the borehole, making it possible to eliminate the need for a casing for protecting the wall of the borehole. Therefore, since it is possible to eliminate the need to press in a casing, it is possible to reduce the effort and cost involved in pressing in a casing.

[0011] (3) In the above (2), the pile removal method may include a step of injecting a lubricant between the outer surface of the concrete part and the inner surface of the borehole before the step of pulling out the pile structure. In this case, since the lubricant is injected between the outer surface of the concrete part and the inner surface of the borehole before the pile structure is pulled out, the peripheral friction of the pile structure during the pulling out can be reduced. Therefore, the pile structure can be easily pulled out.

[0012] (4) The pile structure according to the present disclosure is a pile structure that is to be removed after a predetermined period of time has elapsed. The pile structure includes a concrete portion, a reinforcing bar cage embedded in the concrete portion, and a pipe that is embedded in the concrete portion and fixed to the reinforcing bar cage and into which a replacement material is injected when the pile structure is removed. The pipe has a cap that seals a lower end of the pipe and is removed when the replacement material is injected.

[0013] In this pile structure, a pipe into which the replacement material is injected is fixed to the reinforcing cage, and the reinforcing cage and the pipe are buried in a concrete section. When the pipe is pulled out of the borehole after a predetermined period of time, the replacement material is injected into the pipe fixed to the reinforcing cage. The pipe has a cap that seals its lower end, and the cap is removed when the replacement material is injected into the pipe. The replacement material is injected into the pipe from which the cap has been removed, thereby filling the borehole. Thus, as with the pile construction method and pile removal method described above, the replacement material protects the wall of the borehole, making it possible to eliminate the need for a casing. This reduces the effort and cost involved in pressing in the casing. Effect of the Invention

[0014] According to the present disclosure, the effort and cost involved in pressing in a casing can be reduced. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing an example of a railway viaduct having a pile structure. [Diagram 2] 1A is a plan view of the borehole, and FIG. 1B is a cross-sectional view of the borehole. [Diagram 3] 1A is a plan view showing the reinforcing bar cage and piping installed in the borehole, and FIG. 1B is a cross-sectional view showing the reinforcing bar cage and piping installed in the borehole. [Figure 4] 3(a) is a plan view showing a state in which a tremie pipe is placed in the borehole of FIG. 3(a), and FIG. 3(b) is a cross-sectional view showing a state in which a tremie pipe is placed in the borehole of FIG. 3(b). [Diagram 5] FIG. 1( a ) is a schematic cross-sectional view showing the state in which the pile structure is pulled out and replacement material is filled into the excavated hole. [Figure 6] 1A is a plan view showing a state in which a reinforcing bar cage to which a pipe according to a modified example is fixed is erected in a borehole, and FIG. 1B is a cross-sectional view showing a state in which a reinforcing bar cage to which a pipe according to a modified example is fixed is erected in a borehole. [Figure 7] 6(a) is a plan view showing a state in which a lubricant is being injected into the pipe of Fig. 6(a), and (b) is a cross-sectional view showing a state in which a lubricant has been injected into the pipe of Fig. 6(b). [Figure 8] FIG. 2 is a cross-sectional view of an example lubricant injection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the pile construction method, pile removal method, and pile structure according to the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0017] The pile construction method and pile removal method according to the present embodiment are used for a pile structure that will be removed from the ground after a predetermined period of time. The pile structure 100 according to the present embodiment is temporarily constructed, for example, at a site A of railway viaduct construction for a railway vehicle T. In the present embodiment, the pile structure 100 is a pile that is expected to be removed with certainty. For example, the pile structure 100 is a temporary pile used in a temporary line construction method.

[0018] In this case, at the site A, the pile structure 100 and the temporary pillar C located above it are constructed. More specifically, for example, after the main pile E1, the main pillar F1, the pile structure 100, and the temporary pillar C are constructed and the up and down lines are elevated, the main pile E2 is constructed between the main pile E1 and the pile structure 100, and the main pillar F2 is constructed between the main pillar F1 and the temporary pillar C. Then, the temporary pillar C and the pile structure 100 are removed.

[0019] In this way, the temporary pillar C and the pile structure 100 are removed after a predetermined period of time has elapsed (in the above example, after the main piles E2 and F2 are constructed). Here, the temporary pillar C can be removed relatively easily, but the pile structure 100 may have a length of 20 m or more (or 30 m or more), and in such cases, it may happen that the pile structure 100 cannot be easily removed. Therefore, it is desirable that the pile structure 100 can be easily removed.

[0020] Conventionally, in removing a pile structure, a cylindrical casing is arranged so as to surround the pile structure in a plan view, the casing is pressed into the ground, and the pile structure is removed after the inside of the casing is removed. However, the casing can be very costly to prepare and press in. In particular, when the pile structure 100 has a length of 20 m or more, pressing in the casing takes time and costs money. Therefore, it is required to be able to remove the pile structure 100 without using a casing.

[0021] In the pile construction method, pile removal method, and pile structure 100 according to the present embodiment, the pile structure 100 can be removed without using a casing. Below, examples of the steps of the pile construction method and pile removal method according to the present embodiment will be described. First, the pile construction method according to the present embodiment will be described.

[0022] For example, as shown in Figures 1, 2(a) and 2(b), after the construction of the piles E1 and the columns F1 is completed, the ground 1 at the site A is excavated to form a borehole 2 (a process of forming a borehole in the ground). For example, the ground 1 is drilled with an auger to form the borehole 2, and a stabilizing liquid such as bentonite muddy water is injected into the borehole 2 to protect the wall of the borehole 2.

[0023] Next, as shown in Figures 3(a) and 3(b), a reinforcing bar cage 10 is erected in the borehole 2 (step of erecting the reinforcing bar cage). For example, in a plan view, the reinforcing bar cage 10 has a circular ring shape. The reinforcing bar cage 10 includes a plurality of main reinforcements 11 extending in the vertical direction, a plurality of tie bars 12 arranged in the vertical direction, and a plurality of spacers 13 arranged in the vertical direction. The main reinforcements 11 are arranged in the circumferential direction of the borehole 2, and the tie bars 12 extend in the circumferential direction of the borehole 2.

[0024] The spacers 13 are provided to align the center of the reinforcing bar cage 10 in a plan view with the center of the borehole 2 in a plan view. The reinforcing bar cage 10 has a plurality of spacers 13, and the plurality of spacers 13 are lined up along the circumferential direction of the reinforcing bar cage 10. The spacers 13 are plate-shaped. The spacers 13 have protruding portions that protrude radially outward from the reinforcing bar cage 10, and the protruding portions of the plurality of spacers 13 face the wall of the borehole 2, thereby aligning the position of the reinforcing bar cage 10 in the borehole 2.

[0025] A pipe 20 into which a replacement material 50 (see FIG. 5 ) is injected when the pile structure 100 is removed is fixed to the reinforcing bar cage 10. For example, the pipe 20 is located inside the reinforcing bar cage 10 in a plan view. As an example, the pipe 20 is located at the center of the reinforcing bar cage 10 in a plan view. However, the pipe 20 may be disposed at a position eccentric to the center of the reinforcing bar cage 10 in a plan view, and the position of the pipe 20 in a plan view is not particularly limited.

[0026] The piping 20 extends in the vertical direction. For example, an upper end 21 of the piping 20 protrudes upward from an upper end of the reinforcing bar cage 10, and a lower end of the piping 20 protrudes downward from a lower end of the reinforcing bar cage 10. A cap 22 that seals the lower end of the piping 20 is fixed to the lower end of the piping 20. For example, a lattice structure in which a plurality of reinforcing bars are arranged in a lattice pattern is formed at the lower end of the reinforcing bar cage 10, and the piping 20 is fixed to the lattice structure.

[0027] For example, the inner diameter of the pipe 20 is 100 mm. The pipe 20 is made of, for example, metal. In this case, the pipe 20 is fixed to the lattice structure by, for example, welding, while vertically penetrating the lattice structure. However, the pipe 20 does not have to be made of metal. For example, the pipe 20 may be made of resin (for example, it may be made of polyvinyl chloride), and the material of the pipe 20 is not particularly limited as long as it is not deformed when concrete is poured as described below.

[0028] After the reinforcing bar cage 10 to which the piping 20 is fixed is erected in the borehole 2, as shown in Fig. 4(a) and Fig. 4(b), the concrete pouring piping 30 is inserted into the borehole 2 and concrete is poured to form the concrete section 40 (see Fig. 5) (step of forming the concrete section). One example of the concrete pouring piping 30 is a tremie pipe. The inner diameter of the concrete pouring piping 30 is, for example, 200 mm.

[0029] At this time, the concrete pouring piping 30 is placed inside the reinforcing bar cage 10 in a plan view, and the lower end of the concrete pouring piping 30 is brought close to the lower end (bottom surface) of the borehole 2. For example, the concrete pouring piping 30 is placed at a position eccentric to the center of the reinforcing bar cage 10 in a plan view. However, the concrete pouring piping 30 may be placed at the center of the reinforcing bar cage 10 in a plan view, and the position of the concrete pouring piping 30 in a plan view is not particularly limited.

[0030] For example, the concrete pouring piping 30 is disposed so as to extend vertically adjacent to the piping 20. Then, concrete is poured into the concrete pouring piping 30 with the lower end of the concrete pouring piping 30 approaching the lower end of the borehole 2, and the concrete pouring piping 30 is gradually pulled up while the concrete is filling the borehole 2 from the lower end of the concrete pouring piping 30.

[0031] Concrete is filled into the borehole 2 while the concrete pouring pipe 30 is pulled up, and the concrete is allowed to harden after it reaches the upper end of the borehole 2. At this time, the upper end 21 of the pipe 20 is sealed. Then, the concrete section 40 in which the reinforcing bar cage 10 and the pipe 20 are embedded is formed, completing the pile structure 100 and completing a series of steps in the pile construction method. After that, for example, a temporary pillar C (see FIG. 1) is constructed on the pile structure 100 (concrete section 40) to elevate the railway.

[0032] The pile structure 100 is removed after a predetermined period of time has passed. The "predetermined period of time" refers to the period from when the construction of the pile structure is completed until the pile structure is no longer needed. The "predetermined period of time" is, for example, several months or more and several years or less. In this embodiment, the pile structure 100 is removed after the construction of the main piles E2 and the main columns F2 is completed and the temporary columns C are removed as the railway is elevated.

[0033] The pile removal method according to this embodiment will be described below. First, the cap 22 located at the lower end of the pipe 20 is removed (a cap removing step). For example, the cap 22 is removed by being broken. As a specific example, the upper end 21 of the pipe 20 is opened and a rod-shaped member (a reinforcing bar, for example) that is thinner than the inner diameter of the pipe 20 is moved downward to break the cap 22.

[0034] After removing the cap 22, the pile structure 100 is pulled out from the borehole 2 as shown in Fig. 5 (pile structure pulling out process). For example, the pile structure 100 is pulled out by a multi-pulley pulling out method. Then, at the same time as the pile structure 100 is pulled out, the replacement material 50 is injected from the upper end 21 of the pipe 20 to fill the borehole 2 with the replacement material 50.

[0035] At this time, while the pile structure 100 is being pulled up, the replacement material 50 is injected into the piping 20 to fill the borehole 2 with the replacement material 50. The replacement material 50 is injected from the upper end 21 of the piping 20, passes through the inside of the piping 20, and is discharged from the lower end of the piping 20 that opens at the lower end of the concrete portion 40 into the borehole 2, where it is filled in the borehole 2.

[0036] The replacement material 50 is filled into the borehole 2 to protect the wall of the borehole 2 after the pile structure 100 is pulled out. The replacement material 50 is, for example, a stabilizing liquid. For example, the replacement material 50 is bentonite mud or fluidized sand. Bentonite mud is mud to which bentonite has been added. Fluidized sand is sand to which water has been added to adjust the water content, and is sand to which an agent (a fluidizing agent, for example, an anionic polymer material) has been added and kneaded to increase the fluidity.

[0037] When the replacement material 50 is bentonite mud water, it is easier to obtain and the cost of the replacement material 50 can be reduced compared to when the replacement material 50 is fluidized sand. On the other hand, when the replacement material 50 is fluidized sand, it is easier to perform post-processing after the pile structure 100 is pulled out. That is, after the pile structure 100 is pulled out and the borehole 2 is filled with the replacement material 50, when the replacement material 50 is bentonite mud water, the strength of the replacement material 50 is made equal to the strength of the surrounding ground 1 by adding cement to the replacement material 50. On the other hand, when the replacement material 50 is fluidized sand, it is not necessary to add cement to the replacement material 50, and it is sufficient to wait for the replacement material 50 to harden. As described above, after the replacement material 50 filled in the borehole 2 hardens, a series of steps of the pile removal method is completed.

[0038] Next, the effects obtained from the pile construction method, pile removal method, and pile structure 100 according to this embodiment will be described. As shown in Figures 4(a), 4(b), and 5, in the pile construction method, pile removal method, and pile structure 100 according to this embodiment, a reinforcing bar cage 10 is erected in a borehole 2 formed in the ground 1, and a pipe 20 into which a replacement material 50 is injected is fixed to the reinforcing bar cage 10 in advance when the pile structure 100 is constructed. By pouring concrete into the reinforcing bar cage 10 to which the pipe 20 is fixed, the reinforcing bar cage 10 and the pipe 20 are embedded in a concrete portion 40.

[0039] Then, when the pile structure 100 is pulled out of the borehole 2 after a predetermined period of time has elapsed, the replacement material 50 is injected into the piping 20 fixed to the reinforcing bar cage 10. The replacement material 50 is filled into the borehole 2 by being injected into the piping 20. By filling the borehole 2 with the replacement material 50 while the pile structure 100 is being pulled out, the replacement material 50 protects the wall of the borehole 2, making it possible to eliminate the need for a casing for protecting the wall. This makes it possible to eliminate the need to press in a casing, thereby reducing the effort and cost involved in pressing in a casing.

[0040] Incidentally, this is not a problem when the pile structure 100 is thin and short, but when the pile structure 100 is thick and long, it may become difficult to pull out the pile structure 100 due to peripheral friction of the pile structure 100 against the wall of the borehole 2. Therefore, it may be preferable to reduce the peripheral friction of the pile structure 100 before pulling out the pile structure 100.

[0041] The pile construction method, pile removal method, and pile structure according to the modified example will be described below with reference to Figures 6 to 8. The pile structure according to the modified example differs from the above-described pile structure 100 in that it includes a peripheral friction reducing member 60, but is otherwise the same as the pile structure 100. In the following, explanations that overlap with those of the pile structure 100 will be omitted as appropriate by assigning the same reference numerals.

[0042] 6(a) and 6(b), the peripheral friction reducing member 60 has a first pipe 61 extending in the vertical direction and a second pipe 62 extending from a middle portion of the first pipe 61 radially outward of the reinforcing bar cage 10. The peripheral friction reducing member 60 has a plurality of first pipes 61 and a plurality of second pipes 62.

[0043] The multiple first pipes 61 and the multiple second pipes 62 are arranged in the circumferential direction of the reinforcing bar cage 10. As an example, the number of the first pipes 61 arranged in the circumferential direction and the number of the second pipes 62 arranged in the circumferential direction are six. For example, the first pipes 61 are fixed to the radially inner side of the hoops 12 of the reinforcing bar cage 10. As an example, the first pipes 61 are fixed to the hoops 12 by welding.

[0044] A plurality of second pipes 62 are arranged vertically. The second pipes 62 branch off from the first pipe 61, and the inside of the second pipes 62 communicates with the inside of the first pipe 61. For example, the second pipes 62 are provided at the position of the spacer 13 of the reinforcing bar cage 10. Specifically, the second pipes 62 are attached to the spacer 13 in a state where they are inserted into a through hole formed in the spacer 13, and the radially outer end of the second pipes 62 faces the hole wall of the borehole 2. The first pipe 61 has an opening at the upper end, similar to the piping 20.

[0045] In the pile construction method according to the modified example, first, the borehole 2 is drilled as in the above-mentioned embodiment, and then the reinforcing bar cage 10 is erected. The piping 20 and the peripheral friction reducing member 60 are fixed to the reinforcing bar cage 10 in advance. At this point, the radially outer end of the second pipe 62 is sealed by a cap, similar to the cap 22. After the reinforcing bar cage 10 to which the piping 20 and the peripheral friction reducing member 60 are fixed is erected in the borehole 2, the concrete pouring piping 30 is inserted into the borehole 2 and concrete is poured, forming the concrete portion 40, completing a series of steps, as in the above-mentioned embodiment.

[0046] 7(a), 7(b) and 8, in the pile removal method according to the modified example, before the pile structure is pulled out, a lubricant 70 is injected between the outer surface of the concrete part 40 and the inner surface (hole wall) of the borehole 2 (a step of injecting a lubricant). For example, the peripheral friction reducing member 60 includes an injection pipe 63 used when injecting the lubricant 70, and a pair of upper and lower packers 64 fixed to the lower part of the injection pipe 63.

[0047] The outer diameter of the injection pipe 63 is smaller than the inner diameter of the first pipe 61, and the injection pipe 63 can be inserted into the first pipe 61. The injection pipe 63 is a pipe through which the lubricant 70 passes. An opening 63b through which the lubricant 70 is discharged is formed in the portion of the injection pipe 63 between the pair of packers 64. The lubricant 70 that has passed through the injection pipe 63 enters the second pipe 62 from the opening 63b.

[0048] The lubricant 70 is injected into the injection pipe 63 by, for example, a compressor. The compressor pressurizes the lubricant 70 into the injection pipe 63, thereby removing (e.g., breaking) the cap at the radial end of the second pipe 62. The lubricant 70 is then discharged from the opening 63b and enters the second pipe 62, passing through the second pipe 62 and reaching the wall of the borehole 2. The pair of packers 64 are provided to prevent the lubricant 70 from leaking between the pair of packers 64 and to parts other than the second pipe 62.

[0049] The injection of the lubricant 70 using the injection pipe 63 and the packers 64 is carried out, for example, sequentially from the bottom to the top. In this case, the injection pipe 63 is first moved downward inside the first pipe 61 so that the pair of packers 64 is located at the height of the second pipe 62 at the bottom, and the lubricant 70 is injected into the injection pipe 63 in a state where the height between the pair of packers 64 matches the height of the second pipe 62 at the bottom. As a result, the lubricant 70 is injected into the hole wall of the borehole 2 from the second pipe 62 at the bottom. After that, the injection pipe 63 is raised and the lubricant 70 is injected into the injection pipe 63 in a state where the height of the pair of packers 64 matches the height of the second pipe 62 from the bottom. As a result, the lubricant 70 is injected into the hole wall of the borehole 2 from the second pipe 62 from the bottom.

[0050] Thereafter, the lubricant 70 is sequentially injected into the wall of the borehole 2 while the injection pipe 63 is raised in the same manner as above. Unlike the above, the injection of the lubricant 70 may be performed sequentially from above to below, and the procedure for injecting the lubricant 70 is not particularly limited. Also, FIG. 7(b) shows an example in which a plurality of regions into which the lubricant 70 is injected are arranged vertically and the plurality of regions are separated from each other (do not overlap). However, it is possible to overlap the plurality of regions by increasing the number of second pipes 62 arranged vertically to increase the number of regions into which the lubricant 70 is injected. In this case, it is also possible to inject the lubricant 70 into the entire wall of the borehole 2.

[0051] After the injection of the lubricant 70 into the wall of the borehole 2 is completed, the cap 22 is removed in the same procedure as in the above-described embodiment, and the pile structure is pulled out while injecting the replacement material 50 from above (step of pulling out the pile structure). Then, after the pile structure is pulled out and the borehole 2 is filled with the replacement material 50, a series of steps in the pile removal method is completed.

[0052] As described above, the pile structure, pile construction method, and pile removal method according to the modified example include a step of injecting lubricant 70 between the outer surface of the concrete portion 40 and the inner surface of the borehole 2 before the step of pulling out the pile structure. In this case, since the lubricant 70 is injected between the outer surface of the concrete portion 40 and the inner surface of the borehole 2 before the pile structure is pulled out, it is possible to reduce the peripheral friction of the pile structure during the pulling out. Therefore, the pile structure can be easily pulled out.

[0053] The above describes the embodiment and modified examples of the pile construction method, pile removal method, and pile structure according to the present disclosure. However, the pile construction method, pile removal method, and pile structure according to the present disclosure are not limited to the above-mentioned embodiment or modified examples, and may be further modified within the scope of the gist described in the claims. In other words, the content and order of the steps of the pile construction method and pile removal method, as well as the shape, size, material, number, and arrangement of each part of the pile structure can be appropriately changed within the scope of the above gist.

[0054] For example, in the above-described embodiment, an example has been described in which the replacement material 50, which is bentonite mud or fluidized sand, is used. However, the replacement material may be something other than bentonite mud or fluidized sand. For example, the replacement material may be fluidized treated soil or mortar.

[0055] For example, in the above-described embodiment, the pile structure 100 constructed in railway elevation construction work has been described. However, the pile construction method, pile removal method, and pile structure according to the present disclosure can be adopted in sites other than railway elevation construction work, and the type of site is not particularly limited. [Explanation of symbols]

[0056] 1...ground, 2...drilling hole, 10...reinforcement cage, 11...main reinforcement, 12...hoop, 13...spacer, 20...piping, 21...upper end, 22...cap, 30...concrete pouring pipe, 40...concrete part, 50...replacement material, 60...surface friction reduction member, 61...first pipe, 62...second pipe, 63...injection pipe, 63b...opening, 64...packer, 70...lubricant, 100...pile structure, A...site, C...temporary pillar, E1...main pile, E2...main pile, F1...main pillar, F2...main pillar, T...railroad vehicle.

Claims

1. A pile construction method for constructing a pile structure that is removed after a predetermined period of time has passed, forming a borehole in the ground; A step of erecting a reinforcing bar cage to which a pipe into which a replacement material is injected when the pile structure is removed is fixed, into the excavation hole; pouring concrete into the excavated hole into which the reinforcing steel cage to which the piping is fixed is erected, thereby forming a concrete portion in which the reinforcing steel cage and the piping are embedded; Equipped with Pile construction method.

2. A pile removal method for removing a pile structure constructed by the pile construction method according to claim 1, extracting the pile structure from the borehole; filling the borehole with the replacement material by extracting the pile structure and injecting the replacement material into the piping; Equipped with How to remove piles.

3. Prior to the step of extracting the pile structure, a step of injecting a lubricant between an outer surface of the concrete portion and an inner surface of the borehole is provided. The pile removal method according to claim 2.

4. A pile structure that is removed after a predetermined period of time has passed, Concrete section, a reinforcing bar cage embedded in the concrete section; A pipe that is embedded in the concrete portion, is fixed to the reinforcing bar cage, and into which a replacement material is injected when the pile structure is removed; Equipped with The piping has a cap that seals a lower end of the piping and is removed when the replacement material is injected. Pile structure.

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