Pile foundation construction method and attachment

Abstract

To provide a pile foundation construction method capable of, when excavating a buried pile, preventing a main reinforcement of the pile from bending, and removing an excess concrete part as it is.SOLUTION: An attachment 50 has: a foundation part 52 which is fixed rotatably in a right / left direction on an arm of a hydraulic shove; and a plurality of steel bars 54 which are thinner than a main reinforcement of a pile, are longer than a length from an upper end face of the pile to an upper end of the main reinforcement, extend downward from the foundation part 52 and are aligned with intervals in the right / left direction. Soil around the upper end of the main reinforcement of the pile is scraped by using the hydraulic shovel on which the attachment 50 is attached.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a pile foundation forming method and an attachment. [Background technology]

[0002] Patent Document 1 discloses a pile head treatment method in which a refrigeration pipe that has been buried in concrete in advance is frozen and expanded to cause cracks, and the excess concrete portion of the on-site construction pile is then removed at the cracked portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-143547 Summary of the Invention [Problem to be solved by the invention]

[0004] In-situ pile construction may involve digging a hole from the ground surface, constructing the pile inside it, and then backfilling the hole to bury the entire pile. When the buried pile is dug up again, heavy machinery may come into contact with the main reinforcement extending upward from the top end surface of the buried pile, causing the main reinforcement to bend. In the pile head treatment method of Patent Document 1, if the main reinforcement is bent, the excess concrete cannot be removed as is, and it becomes necessary to chip off part of the excess concrete. The present invention aims to solve such problems, for example, by preventing the main reinforcement from bending and enabling the excess concrete portion to be removed as it is. [Means for solving the problem]

[0005] A pile having concrete with an upper end surface and main reinforcement bars embedded in the concrete, with their upper end portions extending upward from the upper end surface and exposed, and their upper ends located below the ground surface, is constructed in a pile hole excavated downward from the ground surface. The pile hole with the pile constructed therein is backfilled to bury the pile. The area around the backfilled pile hole is excavated to leave the soil around the upper end portions of the main reinforcement bars. A hydraulic excavator with an attachment attached is used to scrape out the soil around the excavated upper end portions of the main reinforcement bars. The attachment has a base fixed to the arm of the hydraulic excavator so as to be rotatable in the left and right directions, and a plurality of reinforcing bars that are thinner than the main reinforcement bars, longer than the length from the upper end surface of the pile to the upper ends of the main reinforcement bars, extending downward from the base, and arranged at a distance in the left and right directions. [Effects of the Invention]

[0006] The length of the rebar in the attachment is longer than the length from the top surface of the pile to the top of the main reinforcement, so it is possible to prevent the base of the attachment from accidentally coming into contact with the main reinforcement of the pile and bending it. Also, because the rebar in the attachment is thinner than the main reinforcement of the pile, even if the rebar in the attachment accidentally comes into contact with the main reinforcement of the pile, the rebar in the attachment will bend, preventing the rebar in the pile from bending. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 10 is a side cross-sectional view showing an example of a pile construction process. [Figure 2] FIG. 10 is a side cross-sectional view showing an example of a backfilling step. [Figure 3] FIG. 10 is a side cross-sectional view showing an example of a backfilling step. [Figure 4] FIG. 10 is a side cross-sectional view showing an example of a backfilling step. [Figure 5] FIG. 10 is a side cross-sectional view showing an example of a root cutting process. [Figure 6] FIG. 10 is a side cross-sectional view showing an example of a root cutting process. [Figure 7] FIG. 10 is a side cross-sectional view showing an example of a root cutting process. [Figure 8]FIG. 10 is a side cross-sectional view showing an example of a root cutting process. [Figure 9] FIG. 2 is a side cross-sectional view showing an example of an attachment. [Figure 10] FIG. 10 is a side cross-sectional view showing an example of a scraping step. [Figure 11] FIG. 10 is a side cross-sectional view showing an example of a pile head treatment process. DETAILED DESCRIPTION OF THE INVENTION

[0008] The pile construction process will be described with reference to FIG. In the pile construction process, piles 20 are constructed. The piles 20 are, for example, on-site construction piles, and are constructed by inserting a framework assembled with a plurality of main reinforcements 21 and a plurality of tie bars 22 into pile holes 12 drilled downward (in the -Z direction) from the ground surface 11, and then pouring concrete 23 into the pile holes. The concrete 23 has, for example, a main body portion 31 and excess concrete 32, and the excess concrete 32 can be removed by cracking the boundary 33 using, for example, the technique described in Patent Document 1. The main reinforcement 21 is, for example, a reinforcing bar extending in the vertical direction (±Z direction), and is embedded in the concrete 23 with its upper end portion extending upward (+Z direction) and exposed from the upper end surface of the concrete 23. The upper end of the main reinforcement 21 is located at a position lower than the ground surface 11. The upper end portion of the main reinforcement 21 is inserted into and covered by the tubular member 24. As shown in the figure, the lower end of the tubular member 24 may be embedded in the excess concrete 32. This prevents the excess concrete 32 from adhering to the main reinforcement 21 and makes it easier to remove the excess concrete 32. The upper end of at least one tubular member 24 is located higher than the upper end of the main reinforcement 21 and lower than the ground surface 11 (for example, at a position about 500 mm higher than the upper end of the main reinforcement 21). The tubular member 24 is made of a relatively soft material, such as urethane foam or a sheath tube, so that even if a portion of the tubular member 24 above the upper end of the main reinforcement 21 is caught during excavation work, the main reinforcement 21 will not bend.

[0009] The backfilling step will be described with reference to FIGS. In the backfilling step, the pile holes 12 in which the piles 20 have been constructed in the pile construction step described with reference to FIG. 1 are backfilled.

[0010] First, as shown in Figure 2, soil 41 is poured into the pile hole 12 and backfilled to a position higher than the upper end of the main reinforcement 21. However, the soil is stopped at a position lower than the upper end of at least one tubular member 24 so that the upper end of at least one tubular member 24 is exposed above the soil 41. For example, the soil is backfilled to a position about 300 mm higher than the upper end of the main reinforcement 21.

[0011] Next, as shown in Figure 3, sand 43 is poured into the pile hole 12 to backfill the pile hole 12. In this case, as in the case of pouring the soil 41, the sand is poured to a position lower than the upper end of at least one tubular member 24 so that the upper end of at least one tubular member 24 is exposed above the soil 41. For example, the sand is poured to a position about 500 mm higher than the upper end of the main reinforcement 21. The sand 43 is colored in a color that can be clearly distinguished from the surrounding soil so that it can be easily seen when excavated.

[0012] Then, as shown in FIG. 4, soil 42 is poured into the pile holes 12 to completely backfill the pile holes 12. As a result, three layers are formed in the pile hole 12 on top of the concrete 23 of the pile 20, namely, a layer of soil 41, a layer of sand 43, and a layer of soil 42, in that order from the bottom.

[0013] The root pruning step will be described with reference to FIGS. In the root cutting step, a wide area including the pile holes 12 backfilled in the backfilling step described with reference to Figs. 2 to 4 is excavated to expose the piles 20 again.

[0014] First, a wide area including the pile holes 12 is excavated to expose only the upper end portions of the tubular members 24 as shown in FIG. With the upper end portion of the tubular member 24 exposed, the approximate position of the pile 20 can be visually confirmed. In addition, since it can be seen that the layer of sand 43 is nearby, it is possible to prevent the layer of sand 43 from being removed by mistake.

[0015] Next, excavation is continued more carefully than before the upper end portion of the tubular member 24 is exposed, and sand 43 is exposed as shown in FIG. At this time, the exposed portion of the tubular member 24 is a portion that does not have the main reinforcement 21 therein, so excavation work can be carried out without worrying about the tubular member 24. The exposed sand 43 shows the cross-sectional shape of the stake hole 12. Because the sand 43 is colored, it can be clearly distinguished from areas other than the stake hole 12. This makes it clear the exact position where the stake 20 is located.

[0016] Therefore, using the exposed sand 43 as a marker, further excavation is carried out around the pile holes 12, leaving them as shown in FIG. Then, as shown in FIG. 8, excavation is performed to a predetermined depth that is lower than the upper end surface of the concrete 23, and the soil in the portions other than the pile holes 12 is removed.

[0017] The attachment 50 will be described with reference to FIG. The attachment 50 is attached to the bucket of a hydraulic excavator, for example, and is used to scrape out the soil 41 remaining around the main reinforcement 21. The attachment 50 includes, for example, a mounting portion 51, a base portion 52, a rotating shaft 53, and a plurality of reinforcing bars 54.

[0018] The mounting portion 51 is a part for attaching the attachment 50 to the arm of a hydraulic excavator, and has a structure (not shown) that allows it to be fixed to the claws of a bucket attached to the arm of the hydraulic excavator using bolts or the like. The base 52 is rotatably attached to the attachment portion 51 via a rotation shaft 53 . The pivot shaft 53 has, for example, a bolt, and rotatably fixes the base 52 to the mounting part 51. The direction in which the base 52 pivots is the left-right direction relative to the mounting part 51 (and the arm of the hydraulic excavator to which the mounting part 51 is attached). If the base 52 becomes tilted while the attachment 50 is in use, the end on the lowered side will hit the ground or concrete 23, causing the base 52 to pivot, returning the base 52 to a substantially horizontal position.

[0019] The reinforcing bars 54 extend further from the tip side of the base 52 in the tip direction and are arranged spaced apart in the left-right direction. Here, the reinforcing bars 54 are thinner than the main reinforcements 21 (for example, D13 to D19). As a result, even if the reinforcing bars 54 accidentally come into contact with the main reinforcements 21, the reinforcing bars 54 are weaker than the main reinforcements 21, so the reinforcing bars 54 will bend but the main reinforcements 21 will not bend. The length that the reinforcing bar 54 extends from the base 52 is longer than the length that the main reinforcement 21 extends from the upper end of the concrete 23. As a result, even if the attachment 50 is operated incorrectly, the tip of the reinforcing bar 54 will come into contact with the concrete 23 before the base 52 comes into contact with the main reinforcement 21, preventing the main reinforcement 21 from being bent by mistake. It is desirable that the reinforcing bar 54 be detachably fixed to the base 52. This allows the reinforcing bar 54 to be easily replaced when the reinforcing bar 54 is bent or when the reinforcing bar 54 is used for a pile 20 in which the main reinforcement 21 extends a different length from the top end of the concrete 23.

[0020] The scraping step will be described with reference to FIG. In the scraping process, a hydraulic excavator equipped with an attachment 50 is used to scrape out the soil 41 and sand 43 remaining around the main reinforcement 21 during the root cutting process described in Figures 5 to 8, such as the area surrounded by the main reinforcement 21. The soil 41 and sand 43 are used to backfill the pile holes 12 and are not compacted. Therefore, they can be easily scraped out with the attachment 50. As described above, the attachment 50 is configured not to bend the main reinforcement 21, and therefore, bending of the main reinforcement 21 can be prevented during the scraping process.

[0021] The pile head treatment process will be described with reference to FIG. In the pile head treatment process, the soil 41 and sand 43 are scraped out in the scraping process described with reference to FIG. 10, and the top end portion of the pile 20 is completely exposed, and the excess concrete 32 is removed from the pile. For example, using the technology described in Patent Document 1, cracks are created at the boundary 33 to separate the excess concrete 32. The separated excess concrete 32 is then lifted upward (in the +Z direction) to remove it. Because the main reinforcement 21 is not bent, there is no need to chip the excess concrete 32, and it can be easily removed. Furthermore, noise, vibration, and dust generated by the chipping work can be prevented.

[0022] The above-described embodiment is an example for facilitating understanding of the present invention. The present invention is not limited thereto, and includes various modifications, changes, additions, or omissions without departing from the scope defined by the appended claims. This can be easily understood by those skilled in the art from the above description.

[0023] When implementing the frozen pile head treatment method on-site, there are cases where the bucket of a hydraulic excavator gets caught on the main reinforcement that protrudes from the excess concrete, bending the main reinforcement. If the main reinforcement is bent, when pulling out the excess concrete, the bent part of the main reinforcement may get caught on the excess concrete, making it impossible to lift. In such cases, it is necessary to remove the concrete on the side where the main reinforcement is bent. Even if the heavy equipment operator works carefully, there are cases where they will hit something. For this reason, it is desirable to know that the pile is nearby and to remove the soil and sand inside the main reinforcement without bending it. (1) Indicating pile position during root cutting work Colored sand is backfilled at a position about 500 mm higher than the main reinforcement so that the operator can visually check the position of the piles while cutting the roots. Extend two to four rebar curing materials (breaking covers or sheath pipes) to a position about 500 mm higher than the main reinforcement so that the position of the piles can be seen. (2) Removal of backfill soil from inside the pile main reinforcement To prevent the main reinforcement from being bent when caught by the excavator bucket, an attachment with multiple rebars thinner than the diameter of the main reinforcement is attached to the bucket and the soil inside the main reinforcement is scraped out. The attachment has a swivel function so that it can be fitted even at an angle. In addition, the length and number of rebars to be scraped out can be adjusted according to the number and spacing of the main reinforcement in the pile. The attachment clamps the bucket and is fixed with bolts so that it can be easily attached and removed. The freezing pile head treatment method is a construction method that minimizes on-site chipping work. If the main reinforcement is bent during excavation, it is necessary to chip the concrete around the bent main reinforcement. By using this technology, the risk of bending the main reinforcement is reduced and the noise, vibration, and dust generated by unnecessary chipping work are suppressed. [Explanation of symbols]

[0024] 11 ground surface, 12 pile hole, 20 pile, 21 main reinforcement, 22 tie, 23 concrete, 24 tubular member, 31 main body, 32 excess concrete, 33 boundary, 41, 42 soil, 43 sand, 50 attachment, 51 mounting part, 52 base, 53 pivot axis, 54 reinforcing bar.

Claims

1. A pile having concrete with an upper end surface and main reinforcement embedded in the concrete, with the upper end portion extending upward from the upper end surface and exposed and the upper end at a position lower than the ground surface, is constructed in a pile hole excavated downward from the ground surface, The pile is buried by backfilling the pile hole in which the pile was created, Excavate the area around the backfilled pile hole, leaving the soil around the upper end portion of the main reinforcement, Using a hydraulic excavator with an attachment attached, scrape out the soil around the upper end portion of the main reinforcement whose periphery has been excavated, The attachment is a base portion fixed to the arm of the hydraulic excavator so as to be rotatable in the left-right direction; a plurality of reinforcing bars that are thinner than the main reinforcing bars, longer than the length from the upper end surface of the pile to the upper end of the main reinforcing bars, extend downward from the base, and are arranged at a distance in the left-right direction; having Pile foundation formation method.

2. In embedding the piles, Put soil into the pile hole to backfill the pile hole to a position higher than the upper end of the main reinforcement and lower than the ground surface, Fill the pile holes with colored sand on top of the soil poured into the pile holes to a level lower than the ground surface, Put soil on top of the sand put into the stake hole to backfill the stake hole, In excavating around the pile hole, By excavating an area including the backfilled pile holes, the sand backfilled in the pile holes is exposed, Excavating around the backfilled pile holes using the exposed sand as a marker; The pile foundation forming method according to claim 1.

3. The pile constructed in the pile hole further has a tubular member into which the upper end portion of the main reinforcement is inserted, and whose upper end is located higher than the upper end of the main reinforcement and lower than the ground surface, In backfilling the pile hole by putting in the sand, backfilling the pile hole to a position lower than the upper end of the tubular member; The pile foundation forming method according to claim 2.

4. the attachment further has a mounting portion that is detachably fixed to a bucket of the hydraulic excavator, The base of the attachment is rotatably fixed to the mounting portion. A pile foundation forming method according to any one of claims 1 to 3.

5. The plurality of reinforcing bars of the attachment are detachably fixed to the base. A pile foundation forming method according to any one of claims 1 to 3.

6. The pile has concrete with an upper end surface and main reinforcement embedded in the concrete, with the upper end portion extending upward from the upper end surface and exposed, and the upper end located at a position lower than the ground surface. The pile is constructed in a pile hole excavated downward from the ground surface, and is used to scrape out the soil around the upper end portion of the main reinforcement of the buried pile by backfilling the pile hole. a base portion fixed to the arm of the hydraulic excavator so as to be rotatable in the left-right direction; a plurality of reinforcing bars that are thinner than the main reinforcing bars, longer than the length from the upper end surface of the pile to the upper end of the main reinforcing bars, extend downward from the base, and are arranged at a distance in the left-right direction; An attachment comprising:

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