Extraction method for existing piles, and fluid supply device

Abstract

To provide an existing pile extraction method capable of restoring the ground by constructing a high-quality solidified material in a place where an existing pile is pulled out.SOLUTION: An existing pile extraction method includes: an edge-cutting step of cutting the edge between the existing pile and the ground by penetrating the borehole casing into the ground while injecting drilling water along the outer periphery of the existing piles left underground; a restoration step of restoring a pile pullout remain by pulling out the existing pile and by solidifying muddy water that accumulates at a pile pullout remain to build a solidified body. In the restoration step, injection and mixing of cement-based solidification liquid is carried out at multiple points in the depth direction of the pile pullout remain.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for extracting an existing pile buried in the ground, and after extracting the existing pile, constructing a solidified body in the pile extraction trace to restore the ground, and a fluid supply device used in the method for extracting the existing pile.

Background Art

[0002] Among various methods for removing existing piles buried in the ground, there is a cutting and extraction method. The cutting and extraction method is a method of cutting the edge between an existing pile and the surrounding ground using a boring casing and then extracting and removing the existing pile. The pile extraction trace is backfilled to ensure the same strength as the natural ground to restore the ground. For example, Patent Document 1 discloses a method for extracting an embedded pile employing the cutting and extraction method.

[0003] In the method for extracting an embedded pile described in Patent Document 1, first, a boring casing that injects foamed water from the tip is rotationally pressed into the ground to bore the surrounding ground of the embedded pile. When the boring casing reaches near the lower end of the embedded pile, this boring casing is extracted and removed. After that, while extracting the embedded pile, fluidized treated soil is supplied to and filled in the pile extraction trace.

[0004] As described above, in Patent Document 1, when the boring casing is rotationally pressed into the ground, foamed water is used instead of boring water. Thereby, dilution of the fluidized treated soil filled in the pile extraction trace is prevented, and a decrease in the strength of the restored ground due to solidification of these fluidized treatment degrees is prevented. However, when the existing pile is large in diameter and long, the extraction work of the existing pile often takes time. In such a case, when supplying fluidized treated soil to the pile extraction trace while extracting the existing pile, the fluidized treated soil may harden during the extraction work, which may cause problems in the work.

[0005] In this context, the slurry solidification method is known as one method for backfilling underground holes. For example, Patent Document 2 discloses a method for removing underground obstacles at a retaining wall construction site using the slurry solidification method. Specifically, while supplying slurry, excavation is carried out while removing underground obstacles such as concrete rubble, boulders, and wooden piles, to construct an underground hole of a predetermined depth. Next, a pipe is installed in the underground hole, and air blow agitation is performed using the pipe to make the slurry stored in the underground hole uniform in the depth direction. After this, a solidifying agent is dropped from the opening of the excavated hole, and air blow agitation is performed again to mix and agitate the solidifying agent and slurry. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-122197 [Patent Document 2] Japanese Patent Application Publication No. 09-13373 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] If a method like the one disclosed in Patent Document 2 is adopted for the extraction method of existing piles, it is possible to efficiently construct a solidified body, backfill the pile extraction site, and restore the ground, even when the extraction work of existing piles takes a considerable amount of time.

[0008] but, Existing piles If the pile is very long, dropping the solidifying agent through the upper opening of the pile extraction site will help to pull out the pile. There is a risk that it will not reach the lower part of the remains. In that case, the solidified body constructed at the pile removal site will be at the top The intensity of expression may differ in the lower part, raising concerns about the quality of the ground restored by backfilling with solidified material. This occurs.

[0009] This invention has been made in view of the above problems, and its main purpose is to restore the ground by backfilling the pile extraction marks of existing piles with a high-quality solidified material. [Means for solving the problem]

[0010] To achieve this objective, the present invention provides an existing pile extraction method comprising: an isolation step of inserting a drilling casing into the ground while spraying drilling water along the outer circumference of the existing pile left in the ground, thereby separating the existing pile from the ground; and a restoration step of extracting the existing pile, solidifying the muddy water accumulated in the pile extraction site to construct a solidified body, thereby restoring the pile extraction site, wherein in the restoration step, a cement-based solidification liquid and air of via the same flow path injection Furthermore, by the air The mixing and stirring is characterized by being carried out at multiple points in the depth direction of the pile extraction site.

[0012] The present invention relates to an existing pile extraction method, which involves the cement-based solidification liquid. and the air of via the same flow path Injection and Furthermore, by the air The mixing and stirring is performed at multiple points in a plan view of the pile extraction site.

[0013] The present invention relates to an existing pile extraction method, which involves the cement-based solidification liquid. and the air of via the same flow path Injection and Furthermore, by the air The mixing and stirring are characterized by being carried out using an air blow pipe.

[0014] The fluid supply device of the present invention comprises an air blow pipe and a branch pipe attached to the base end of the air blow pipe, the branch pipe being provided with an air inlet to which a compressed air supply pipe is connected and a solidification liquid inlet to which a solidification liquid supply pipe is connected. The system is configured to allow injection of the solidification liquid from the solidification liquid supply pipe and the air from the compressed air supply pipe through the same flow path, as well as mixing and stirring with the air, using the air blow pipe. It is characterized by the following:

[0015] According to the existing pile extraction method and fluid supply device of the present invention, cement-based solidification liquid is injected and mixed at multiple points in the depth direction of the pile extraction site where muddy water is stored, or continuously in the depth direction. This makes it possible to backfill and restore the pile extraction site with a high-quality solidified body that exhibits uniform strength in the depth direction, even when the existing pile is very long.

[0016] In addition, if the injection and mixing agitation of the cement-based solidifying liquid are carried out at a plurality of points in plan view, when the existing pile has a large diameter and the plan view area of the pile extraction trace is large, it is possible to fill and restore the pile extraction trace with a high-quality solidified body that exhibits uniform strength not only in the depth direction but also in the plan view direction.

[0017] Furthermore, if a fluid supply device is adopted, the injection pressure when injecting the cement-based solidifying liquid can be easily adjusted. Thereby, even when the existing pile is long and the pile extraction trace has a large depth, it is possible to efficiently inject the cement-based solidifying liquid at a plurality of points in the depth direction or continuously in the depth direction.

Effect of the Invention

[0018] According to the present invention, since the injection and mixing agitation of the cement-based solidifying liquid are carried out at a plurality of points in the depth direction of the pile extraction trace where muddy water is stored or continuously in the depth direction, it is possible to fill and restore the pile extraction trace with a high-quality solidified body that exhibits uniform strength in the depth direction without being affected by the size and length of the existing pile.

Brief Description of the Drawings

[0019] [Figure 1] It is a diagram showing the procedure of the edge cutting step in the extraction method of an existing pile in an embodiment of the present invention. [Figure 2] It is a diagram showing the procedure of the restoration step in the extraction method of an existing pile in an embodiment of the present invention (First Embodiment). [Figure 3] It is a diagram showing a fluid supply device in an embodiment of the present invention. [Figure 4] It is a diagram showing the procedure of the restoration step in the extraction method of an existing pile in an embodiment of the present invention (Second Embodiment). [Figure 5] It is a diagram showing the procedure of the restoration step in the extraction method of an existing pile in an embodiment of the present invention (Third Embodiment). [Figure 6]This figure shows the procedure for the restoration process in the existing pile extraction method according to an embodiment of the present invention (fourth embodiment). [Modes for carrying out the invention]

[0020] This invention is a method for removing existing piles, often carried out in conjunction with building demolition or reconstruction. It employs a so-called "edge-cutting extraction" method, which uses a drilling casing to isolate the existing pile from the ground. This method is particularly suitable for extracting large, long, and large-diameter existing piles, such as those exceeding 30 meters in length. The details of this existing pile extraction method will be explained below with reference to Figures 1 to 6.

[0021] <<Extraction method for existing piles>> In this embodiment, we will explain in detail using an existing concrete pile 10 as an example, as shown in Figure 1(a), but the type of existing pile 10 is not limited in any way. Furthermore, any method can be used to extract the existing pile 10 after it has been separated from the ground, such as a leader type or a suspension type.

[0022] To give a general overview of the existing pile extraction method, first, as shown in Figures 1(b) to (d), an isolation extraction method using a drilling casing 40 is employed as an isolation process to isolate the existing pile 10 remaining in the ground from the ground. Next, as shown in Figures 1(e) to (f), the existing pile 10 is extracted and removed from the ground. After this, as a restoration process, a cement-based solidification liquid C is injected into the pile extraction site H and mixed.

[0023] In this way, a solidified body 20 is constructed, and the pile extraction site H is restored using the backfill ground made of this solidified body 20. At this time, one of the major features of the existing pile extraction method is that, as shown in Figures 2 and 4, cement-based solidification liquid C is injected at multiple points in the depth direction, or as shown in Figure 5, cement-based solidification liquid C is continuously injected in the depth direction and mixed and stirred with bentonite-containing slurry M3.

[0024] The cement-based solidification liquid C only needs to contain at least a cement-based solidification agent and water, and any material commonly used in slurry solidification methods or ground improvement methods can be used. Bentonite-containing slurry M3 will be discussed later.

[0025] In this way, by injecting cement-based solidification liquid C at multiple points in the depth direction, or continuously in the depth direction, even when the pile extraction site H is at great depth due to the long length of the existing pile 10, the solidified body 20 constructed at the pile extraction site H can exhibit uniform strength in the depth direction. As a result, the pile extraction site H can be restored with backfill ground consisting of a high-quality solidified body 20.

[0026] In the restoration process described above, it becomes necessary to adjust the injection pressure of the cement-based solidification liquid C according to the injection depth of the cement-based solidification liquid C. Therefore, in this embodiment, a fluid supply device 30 as shown in Figure 3 is employed to improve work efficiency by performing both the injection pressure adjustment of the cement-based solidification liquid C and air blow agitation with the same device.

[0027] ≪≪Fluid supply device≫≫ As shown in Figure 3, the fluid supply device 30 includes an air blow pipe 31 inserted into the pile extraction site H, a flexible pipe 32, and a swivel joint 33 connecting one end of the pipe 32 to the base end of the air blow pipe 31. The fluid supply device 30 also includes a branch pipe 34 connected to the other end of the pipe 32, and this branch pipe 34 is provided with an air inlet 341 to which a compressed air supply pipe 35 is connected, and a solidification liquid inlet 342 to which a solidification liquid supply pipe 36 is connected.

[0028] This allows the fluid supply device 30 to supply air from the air compressor Ac to the bentonite-containing slurry M3 via the air blow pipe 31. Furthermore, the solidification liquid manufacturing device CM can produce a cement-based solidification liquid C, which can then be injected into the bentonite-containing slurry M3 via the air blow pipe 31. Additionally, the air supplied from the air compressor Ac can be used to adjust the injection pressure of the cement-based solidification liquid C injected into the bentonite-containing slurry M3.

[0029] In addition, by employing this fluid supply device 30, the injection of cement-based solidification liquid C and air blow agitation can be performed simultaneously. The air blow pipe 31 may be a single pipe or a double pipe, or any other configuration.

[0030] The procedure for using the above-mentioned fluid supply device 30 in the restoration process and performing the extraction method for the existing piles 10 will be described below as the first to fourth embodiments, with reference to Figures 2 and 4 to 6.

[0031] <<<First Embodiment>>> ≪Edge-cutting process≫ First, as shown in Figure 1(a), as a preparatory step, a protective pipe 50 for the opening of the existing pile 10 left in the ground is driven in from the ground surface to a predetermined depth.

[0032] Next, as shown in Figure 1(b), the drilling casing 40 is driven into the ground along the outer circumference of the existing pile 10 while injecting drilling water W. Any type of casing widely used in the edge-cutting extraction method may be used for the drilling casing 40, and its lower end is provided with a cutting blade and an injection nozzle 41 from which drilling water W can be injected.

[0033] As shown in Figure 1(c), when the lower end of the drilling casing 40 reaches a position below the tip of the existing pile 10, the injection of drilling water W is stopped, and the drilling casing 40 is pulled out of the ground and removed. This separates the existing pile 10 from the surrounding ground, as shown in Figure 1(d).

[0034] After the drilling casing 40 is withdrawn and removed, as shown in Figure 1(e), the existing pile 10 is withdrawn while bentonite liquid M2 is injected. As a result, the pile withdrawal site H becomes a reservoir of bentonite-containing slurry M3, as shown in Figure 1(f). The bentonite-containing slurry M3 is a mixture of bentonite liquid M2 and slurry M1, which is a mixture of soil G and drilling water W. The soil G includes soil that fell from the ground when the drilling casing 40 was driven into the ground, when it was withdrawn and removed, or when the existing pile 10 was withdrawn.

[0035] ≪Restoration Process≫ Once the existing piles 10 have been removed, as shown in Figure 2(a), the tip of the air blow pipe 31 of the fluid supply device 30 is inserted to a predetermined depth, and the cement-based solidification liquid C is injected through this air blow pipe 31. After this, with the air blow pipe 31 still inserted, air blow agitation of the cement-based solidification liquid C and the bentonite-containing slurry M3 is performed, as shown in Figure 2(b).

[0036] Subsequently, as shown in Figures 2(c) and (d), the tip of the air blow pipe 31 is brought to the vicinity of the bottom of the pile extraction site H, and the cement-based solidification liquid C is injected and air blow agitation is performed. This mixes and agitates the entire pile extraction site H in the depth direction. After the agitation is completed, curing is performed to construct a homogeneous solidified body 20 with uniform strength in the height direction, as shown in Figure 2(e).

[0037] For example, if the pile length is about 40m and the pile diameter is about 2m, cement-based solidification liquid C is injected at a point 15m from the bottom and at a point 5-8m from the bottom. In addition, air blow agitation is performed at both points using an air compressor set to 9 atmospheres for a total of about 180 minutes. This corresponds to 1 minute / m³ relative to the volume of the pile extraction site H. 3 This is based on the finding that it is preferable to use a certain amount of stirring time as a guideline. In other words, when the pile diameter is about 2m, a drilling casing 40 with a diameter of about 2.4m is used. And when the pile length is 40m, the volume of the pile extraction site H is about 180m³. 3 Therefore, the total stirring time is set to 180 minutes.

[0038] Furthermore, it is preferable to allocate a greater amount of time to the mixing process as the mixing position approaches the bottom. In addition, the amount of cement-based solidification liquid C injected should be adjusted as appropriate according to the ground conditions at the site and the required strength of the solidified body 20.

[0039] In the first embodiment described above, the cement-based solidification liquid C was injected and air-blown agitated at two points in the depth direction of the pile extraction site H, from top to bottom in the depth direction. However, the method is not limited to this, and for example, the cement-based solidification liquid C may be injected at two points in the depth direction and air-blown agitation may be performed at four points in the depth direction. Increasing the number of agitation points in this way can shorten the total agitation time.

[0040] Taking the above example of a pile with a length of approximately 40m and a pile diameter of approximately 2m, the inside of the pile extraction site H can be uniformly mixed by setting the mixing time to approximately 10 minutes at the 10m point, 20 minutes at the 20m point, 30 minutes at the 30m point, and 60 minutes at the bottom. In other words, a time reduction of approximately 60 minutes can be achieved. Furthermore, the process of injecting the cement-based solidification liquid C and mixing it with air blow may be carried out from the bottom in the depth direction upwards.

[0041] <<Second Embodiment>> ≪Edge-cutting process≫ In the second embodiment, similar to the first embodiment, the existing pile 10 is isolated from the surrounding ground using the procedure described with reference to Figure 1. Then, after the drilling casing 40 is withdrawn and removed, the existing pile 10 is withdrawn while bentonite liquid M2 is injected. As a result, the pile withdrawal site H becomes a state where bentonite-containing slurry M3 is stored, as shown in Figure 1(f).

[0042] ≪Restoration Process≫ Next, as shown in Figure 4(a), the tip of the air blow pipe 31 is brought to the vicinity of the bottom of the pile extraction site H, and cement-based solidification liquid C is injected while air blow agitation with bentonite-containing slurry M3 is performed. Performing both the injection of cement-based solidification liquid C and air blow agitation simultaneously in this way can shorten the working time and contribute to improved work efficiency.

[0043] Furthermore, these operations are carried out sequentially from the bottom to the top in the depth direction, as shown in Figures 4(b) and (c). As a result, the entire inside of the pile extraction site H is mixed and stirred in the depth direction, as shown in Figure 4(d). After the stirring is completed, curing is performed to construct a homogeneous solidified body 20 that exhibits uniform strength in the height direction, as shown in Figure 4(e).

[0044] In the second embodiment described above, the process of injecting the cement-based solidification liquid C while agitating it with air blow was carried out at three points in the depth direction of the pile extraction site H, from bottom to top in the depth direction. However, it is not limited to this, and may be carried out at two or more points, or from top to bottom in the depth direction.

[0045] ≪≪Third Embodiment≫≫ ≪Edge-cutting process≫ In the third embodiment, as in the first and second embodiments, the existing pile 10 is isolated from the surrounding ground using the procedure described with reference to Figure 1. Then, after the drilling casing 40 is withdrawn and removed, the existing pile 10 is withdrawn while bentonite liquid M2 is injected. The pile withdrawal site H becomes a state where bentonite-containing slurry M3 is stored, as shown in Figure 1(f).

[0046] ≪Restoration Process≫ Once the existing piles 10 have been removed, the tip of the air blow pipe 31 of the fluid supply device 30 is inserted to a predetermined depth, as shown in Figures 5(a) to (c). Subsequently, the cement-based solidification liquid C is injected through the air blow pipe 31, and the bentonite-containing slurry M3 is mixed with the liquid using air blow while the air blow pipe 31 is moved downward at a constant speed.

[0047] In other words, in the third embodiment, both the injection of the cement-based solidification liquid C and the air-blowing agitation are performed simultaneously and continuously in the depth direction. Figure 5 illustrates a case where the tip of the air blow pipe 31 is moved downward at a constant speed, but it is not limited to this, and it may also be moved from bottom to top.

[0048] Thus, the entire area within the pile extraction site H is mixed and stirred in the depth direction, as shown in Figure 5(c). After the stirring is complete, curing is performed to construct a homogeneous solidified body 20 that exhibits uniform strength in the height direction, as shown in Figure 5(d).

[0049] ≪≪Fourth Embodiment≫≫ ≪Edge-cutting process≫ In the fourth embodiment, similar to the first to third embodiments, the existing pile 10 is isolated from the surrounding ground using the procedure described with reference to Figure 1. After the drilling casing 40 is withdrawn and removed, the existing pile 10 is withdrawn while bentonite liquid M2 is injected, and the pile withdrawal site H is filled with bentonite-containing slurry M3, as shown in Figure 1(f).

[0050] ≪Restoration Process≫ Next, as shown in Figure 6(a), the tips of the two air blow pipes 31 constituting the fluid supply device 30 are inserted to a predetermined depth in the pile extraction site H, and cement-based solidification liquid C is injected at two points in a plan view. Then, with the air blow pipes 31 still inserted, air blow agitation of the cement-based solidification liquid C and bentonite-containing mud M3 is performed, as shown in Figure 6(b).

[0051] Next, the tip of the air blow pipe 31 is moved below the pile extraction site H, and the cement-based solidification liquid C is injected and mixed with air blow. This ensures that the entire pile extraction site H is mixed and stirred in the depth direction. By performing the injection and mixing of the cement-based solidification liquid C at two points in a plan view, it becomes possible to backfill and restore the pile extraction site H with a high-quality solidified body 20 that exhibits uniform strength not only in the depth direction but also in the plan view direction, even when the existing pile 10 is large in diameter and the plan view area of ​​the pile extraction site H is vast.

[0052] In the fourth embodiment, two air blow pipes 31 were used, but the number is not limited to this, and the number may be increased as appropriate depending on the plan view shape of the existing pile 10. When multiple air blow pipes 31 are arranged, it is advisable to arrange them with sufficient spacing between them so that the cement-based solidification liquid C injected into the pile extraction site H from each air blow pipe 31 does not affect each other.

[0053] According to the above-described method for extracting existing piles, it is possible to backfill and restore the pile extraction site H with a high-quality solidified body 20 that exhibits uniform strength in both the depth direction and the plan view direction, regardless of the size, length, or shape of the existing pile 10, such as whether it is long or large in diameter.

[0054] The existing pile extraction method and fluid supply device of the present invention are not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0055] 10 Existing piles 20. Solidified body (backfill ground) 30 Fluid supply device 31 Air blow tube 32 Piping 33 Swivel Joint 34 Branch pipes 341 Air inlet 342 Solidified liquid inlet 35 Compressed air supply pipe 36 Solidified liquid supply pipe 40 Drilling casing 50 Mouth protection tube C Cement-based solidification liquid AC air compressor CM solidified liquid manufacturing equipment M1 muddy water M2 Bentonite Liquid M3 Bentonite-containing mud G Soil and Sediment W Drilling water H pile extraction marks

Claims

1. A cutting process involves inserting a drilling casing into the ground while spraying drilling water along the outer circumference of an existing pile left in the ground, thereby cutting the connection between the existing pile and the ground, A restoration process involves removing the existing piles, solidifying the muddy water stored in the pile removal area to construct a solidified body, and restoring the pile removal area. A method for extracting existing piles, In the aforementioned restoration process, A method for extracting existing piles, characterized by injecting a cement-based solidification liquid and air through the same flow path, and mixing and stirring with the air, at multiple points in the depth direction of the pile extraction site.

2. In the method for extracting existing piles according to claim 1, An existing pile extraction method characterized by injecting the cement-based solidification liquid and the air through the same flow path and mixing and stirring with the air at multiple points in a plan view of the pile extraction site.

3. In the method for extracting existing piles according to claim 1 or 2, An existing pile extraction method characterized by performing the injection of the cement-based solidification liquid and the air through the same flow path, as well as the mixing and stirring by the air, using an air blow pipe.

4. Air blow pipe and The air blow pipe is equipped with a branch pipe attached to its base end, In the branch pipe, An air inlet to which a compressed air supply pipe is connected and a solidification liquid inlet to which a solidification liquid supply pipe is connected are provided. A fluid supply device characterized in that it is configured to allow injection of solidifying liquid from the solidifying liquid supply pipe and air from the compressed air supply pipe through the same flow path, and mixing and stirring with the air, using the air blow pipe.

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