Existing structure removing method

Abstract

To provide an existing structure removing method capable of efficiently removing an existing structure even when the existing structure buried in the ground is removed under an overhead space restriction.SOLUTION: An existing structure removing method comprises: A step of fitting a tensile member 11 to an existing structure 10 and pressing-in a casing 30 between the existing structure 10 and its surrounding foundation G; B step of installing a structure grip band 60 at a top end 35 of the casing 30; C step of raising the tensile member 11 by a press-in machine 20, gripping the existing structure 10 by the structure grip band 60 to support it on the casing 30, and cutting a removal region of the existing structure 10 to remove it; and D step of chopping off a new top end generated in the existing structure to expose a head of the tensile member 11, connecting it to another tensile member 14, raising the other tensile member 14 by the press-in machine 20, gripping the existing structure 10 by the structure grip band 60 to support it on the casing 30, and cutting the removal region of the existing structure 10 to remove it.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a method for removing an existing structure. [Background technology]

[0002] When pulling up and removing existing structures such as piles buried underground, there are many cases where it is practically impossible to pull up the existing structure as a whole if there are headroom restrictions due to the presence of above-ground structures above. By the way, one method of removing existing underground structures is to erect a casing while excavating around the existing structure, crushing the existing structure inside the casing with a chisel or breaker, etc., and cutting and dividing the reinforcing bars and the like into small pieces using gas cutting, etc., and then transporting these out using a hammer grab, etc. Here, if the existing structure is larger than the casing to be used, the above procedure will be carried out in multiple stages. When carrying out this type of removal method under headroom restrictions, for example, restrictions arise on the dimensions of the hammer grab when it is used, so the current situation is that the caisson foundation method is applied or a large-scale device is separately manufactured to carry out the removal work, and both the caisson foundation method and the separate manufacture of the device are factors that increase the removal work costs.

[0003] Therefore, Patent Document 1 proposes a method for removing existing structures, which can remove existing structures efficiently with a high degree of safety, even when removing existing structures buried underground under headroom restrictions, without the need for large-scale, special equipment. This method of removing an existing structure includes a first step of attaching a tension member to the existing structure buried underground, and using an excavator to install a casing between the existing structure and the ground surrounding it to separate the existing structure from the ground, installing a support frame on the ground and supporting the tension member on the support frame, and a second step of pulling the tension member upward to pass the existing structure through the inside of the excavator and pull part of it up to the ground, drilling a hole at a midpoint of the existing structure that has been pulled up to the ground, inserting a support member into this hole and fixing the support member to ensure a fixed position of the existing structure, and cutting off and removing the portion of the existing structure above the attachment point of the support member. Furthermore, the method includes a third step of attaching a tension member to the new top end of the existing structure created by partially cutting the existing structure, supporting the tension member on a mounting frame, using an excavator to lift the existing structure to the ground, drilling a separate hole at a midpoint of the existing structure that has been lifted to the ground, inserting a support member into this separate hole, fixing the support member to ensure a fixed position of the existing structure, and cutting and removing the portion of the existing structure above the attachment point of the support member, and the method repeats the third step to remove the existing structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-218861 A Summary of the Invention [Problem to be solved by the invention]

[0005] The method of removing an existing structure described in Patent Document 1 does not require the preparation of large-scale special equipment, even when removing an existing structure buried underground under headroom restrictions. However, each time the existing structure is pulled up to the ground, holes must be drilled at an intermediate position, support members must be inserted, and the support members must be fixed in place to ensure that the existing structure is fixed in place, leaving room for improvement in terms of the amount of work required.

[0006] To provide a method for removing an existing structure, which can efficiently remove an existing structure buried underground without the need for a large-scale special device, even when the existing structure is to be removed under headroom restrictions. [Means for solving the problem]

[0007] In order to achieve the above object, one aspect of the method for removing an existing structure according to the present invention includes: Process A involves attaching tension members to an existing structure buried underground, and using a press-in machine to press a casing between the existing structure and the surrounding ground to separate the existing structure from the ground; Step B: installing a structure holding band for supporting the existing structure on the top end of the casing or on the construction base on the ground; A process C of pulling up the tension member with the press-in machine or a separate lifting machine, passing the existing structure through the inside of the structure gripping band, gripping the existing structure with the structure gripping band and supporting it on the casing or the construction base, and cutting and removing a removal area of ​​the existing structure that is above the gripping point by the structure gripping band; and a step D of chipping off a new top end of the existing structure resulting from the cutting to expose a head of the tension member and connecting it to a separate tension member, supporting the separate tension member on the press-in machine or the separate lifting machine, releasing the grip of the existing structure by the structure gripping band, lifting the separate tension member with the press-in machine or the separate lifting machine, passing the existing structure through the inside of the structure gripping band, gripping the existing structure with the structure gripping band and supporting it on the casing or the construction base, and cutting and removing a removal area of ​​the existing structure that is above the gripping point by the structure gripping band. The step D is repeated to remove the existing structure.

[0008] According to this embodiment, the pulled-up existing structure is grasped with a structure gripping band and supported on the casing or construction base surface, and the removal area above the gripping point is cut and removed, and this process is repeated to remove the existing structure.By doing so, even when the existing structure is removed under headroom restrictions, there is no need to prepare large-scale special equipment, and the existing structure can be removed efficiently.

[0009] Here, "existing structures" include concrete or steel caissons and foundations buried in the ground, cast-in-place piles buried in the ground, prefabricated piles such as steel pipe piles and PHC piles, etc. When pulling up an existing structure, a press-in machine is used to press-in short casings into the ground one after another in order to separate the existing structure from the surrounding ground. The reason for adding short casings is to comply with headroom restrictions.

[0010] When lifting an existing structure, a boring machine or the like is used to drill a hole to a specified depth on the top of the existing structure, a tension member made of rebar or tendon is inserted into the hole, and the tension member is attached to the existing structure by filling it with grout, etc. Then, the upper end of the attached tension member is lifted by a press-in machine or a separate lifting machine and passed through the inside of the structure gripping band, and the existing structure can be gripped by the structure gripping band. The structure gripping band is supported on the top of the casing or on the construction base, which can be set on the ground, a steel plate laid on the ground, or the top surface of a platform made of multiple steel sections arranged in a crisscross pattern on the ground.

[0011] Another aspect of the method for removing an existing structure according to the present invention is to In the step A, a center hole jack is attached directly or indirectly to the top end of the casing, and the existing structure is cut using the center hole jack.

[0012] According to this embodiment, by using a center hole jack to cut the hip of the existing structure, construction problems such as the surrounding ground adhering to the existing structure being lifted and the edge of the structure not being severed, making it difficult to lift the structure, can be prevented. Here, "cutting the foundation" refers to releasing the close contact between an existing structure and the surrounding ground. In addition, "attaching a center hole jack directly or indirectly to the top end of the casing" means not only literally attaching a center hole jack directly to the top end of the casing, but also arranging, for example, multiple shaped steel members (H-shaped steel members, etc.) on the top end of the casing and attaching a center hole jack to the multiple shaped steel members.

[0013] Another aspect of the method for removing an existing structure according to the present invention is to The method further includes a step E of pulling out and removing the casing, The method is characterized in that the casing is pulled up partway, the casing is gripped and supported by a casing gripping band on the ground, the cavity created by pulling the casing up partway is backfilled with backfill material, and this set of pulling the casing up partway, gripping it, and backfilling with backfill material is repeated.

[0014] According to this aspect, the casing is pulled up halfway, and the cavity created by this pulling is filled with backfilling material. This process is repeated, so that the hole wall is prevented from collapsing when the casing is pulled up, and the backfilling material can be reliably filled into the cavity that is formed. Here, of the pulled up casings, the casings above the casing gripping band are removed by being cut and removed, or by removing the short casing, or the like.

[0015] In another aspect of the method for removing an existing structure according to the present invention, In step E, a jack is placed on the casing gripping band, a material to be pushed up is attached to an upper region of the casing above the casing gripping band, and in addition to lifting the casing with the pressing machine or a separate lifting machine, the casing is lifted by pushing up the material to be pushed up with the jack.

[0016] According to this aspect, by placing a jack on the casing gripping band and using the jack to push up the pushed-up material attached to the upper region of the casing above the casing gripping band, even if the lifting force is insufficient when lifting the casing using a press-in machine or a separate lifting machine, the casing can be lifted without having to separately prepare a higher-performance press-in machine, etc. Effect of the Invention

[0017] According to the method for removing an existing structure of the present invention, even when an existing structure buried underground is to be removed under headroom restrictions, there is no need to prepare large-scale, special equipment, and the existing structure can be removed efficiently. [Brief description of the drawings]

[0018] [Figure 1] FIG. 4 is a process diagram illustrating step A of an example of a method for removing an existing structure according to an embodiment. [Diagram 2] 1, is a process diagram illustrating step A of an example of the method for removing an existing structure according to the embodiment. FIG. [Diagram 3] 2, is a process diagram illustrating step A of the example of the method for removing an existing structure according to the embodiment. FIG. [Figure 4] FIG. 2 is a perspective view of an example of a ruler steel plate. [Diagram 5] 5 is a process diagram illustrating step A of the example of the method for removing an existing structure according to the embodiment, following FIG. [Figure 6] 5, is a process diagram illustrating step A of the example of the method for removing an existing structure according to the embodiment. FIG. [Figure 7]FIG. 11 is a process diagram illustrating process B of an example of a method for removing an existing structure according to an embodiment. [Figure 8] FIG. 2 is a plan view of an example of a structure gripping band. [Figure 9] FIG. 13 is a process diagram illustrating step C of an example of a method for removing an existing structure according to an embodiment, and is also a diagram illustrating step D. [Figure 10] FIG. 10 is an enlarged view of a portion X in FIG. [Figure 11] 9, and is a process diagram illustrating step C of the example of the method for removing an existing structure according to the embodiment, and is a diagram illustrating step D together. FIG. [Figure 12] FIG. 12 is an enlarged view of part XII in FIG. [Figure 13] FIG. 11 is a process diagram illustrating step E of an example of a method for removing an existing structure according to an embodiment. [Figure 14] 13 , and is a process diagram illustrating process E of the example of the method for removing an existing structure according to the embodiment. [Figure 15] FIG. 13 is a diagram illustrating an example of an auxiliary method in step E. [Figure 16] 14 , and is a process diagram illustrating step E of the example of the method for removing an existing structure according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, a method for removing an existing structure according to an embodiment will be described with reference to the accompanying drawings. In this specification and the drawings, substantially identical components are designated by the same reference numerals, and duplicated descriptions may be omitted.

[0020] [Method for removing an existing structure according to the embodiment] An example of a method for removing an existing structure according to an embodiment will be described with reference to FIGS. Here, Figs. 1 to 3, 5, and 6 are process diagrams for explaining step A of an example of a method for removing an existing structure according to the embodiment, and Fig. 4 is a perspective view of an example of a ruler steel plate. Fig. 7 is a process diagram for explaining step B of an example of a method for removing an existing structure according to the embodiment, and Fig. 8 is a plan view of an example of a structure gripping band. Figs. 9 and 11 are process diagrams for explaining step C of an example of a method for removing an existing structure according to the embodiment, and are figures for explaining step D together, Fig. 10 is an enlarged view of part X in Fig. 9, and Fig. 12 is an enlarged view of part XII in Fig. 11. Figs. 13, 14, and 16 are process diagrams for explaining step E of an example of a method for removing an existing structure according to the embodiment, and Fig. 15 is a view for explaining an example of an auxiliary construction method in step E.

[0021] In the following, we will use cast-in-place concrete piles as an example of an existing structure, but the existing structure to be removed may be other than cast-in-place concrete piles, prefabricated piles such as steel pipe piles, reinforced concrete or steel caissons, etc.

[0022] As shown in Figure 1, the area in which the existing pile 10 is to be removed includes a bridge (highway) (not shown) and the like, and since a headway limit level has been set, it is assumed that construction work must be carried out within a range below the headway limit level.

[0023] In the method for removing an existing structure, first, as shown in Fig. 1, a liner plate L is driven near the surface of the ground G in which the existing piles 10 are buried, so as to surround the existing piles 10. Furthermore, a drainage tank K is constructed by a backhoe B on the ground surface to the side of the liner plate L.

[0024] Next, as shown in Fig. 2, a coring machine C is installed on the top end of the existing pile 10, and a hole for erecting the tension member is drilled to near the bottom end of the existing pile 10. Next, an injection pipe (not shown) is inserted into the drilled hole, water is pumped in to clean the inside of the drilled hole, and then cement milk is injected into the drilled hole to erect the tension member 11. Here, a PC steel bar is used for the tension member 11.

[0025] Next, as shown in Fig. 3, a ruler steel plate 40 is placed on the ground surface corresponding to the existing pile 10. Here, as shown in Fig. 4, the ruler steel plate 40 is a long steel plate with a guide opening 42 having a larger diameter than the short casing 31 to be inserted in a later process, and a step 45 to be stepped on by the press-in machine 20 is provided on the opposite side to the guide opening 42.

[0026] Returning to Fig. 3, the ruler steel plate 40 is installed on the ground surface so that its guide opening 42 is located directly above the existing pile 10. Then, the press-in machine 20 hanging the short casing 31 approaches the construction position, and the press-in machine 20 steps on the step 45 of the ruler steel plate 40, automatically fixing the position of the ruler steel plate 40.

[0027] The press-in machine 20 in the illustrated example is a BG (multi-function large diameter drilling) drilling machine, in which a mast 23 is mounted on a base machine 21 so as to be movable vertically and horizontally, and a rotary drive 25 is attached to the mast 23 so as to be movable up and down.

[0028] 3 shows a state in which two short casings 31 connected to each other are suspended from the rotary drive 25. Since the construction site in the illustrated example has a headroom limit level, a long casing cannot be pressed in at once, so a method is applied in which a plurality of short casings 31 are successively added to form a casing 30 (see FIG. 6) of a length equivalent to that of the existing pile 10. As shown in FIG. 3, a sand pump S is installed in the boiler yard K when the short casing 31 is rotary pressed in.

[0029] Next, as shown in Fig. 5, a plant P is installed behind the press-in machine 20, and while drilling water is fed from the plant P into the short casing 31 through a hose H1 for feeding drilling water, the press-in machine 20 rotates the short casing 31 in the X1 direction and presses it in the X2 direction to perform rotary press-in. The drilling water is stored in a boiler pit K and is collected by a sand pump S into the plant P through a hose H2 for returning drilling water.

[0030] By sequentially performing the above-mentioned rotational pressing of the short casing 31 and adding another short casing 31, a casing 30 is installed that completely surrounds the existing pile 10 over its entire length, as shown in Figure 6, and the existing pile 10 is separated from the surrounding ground G.

[0031] Next, as shown in Figure 6, multiple (e.g., two) H-shaped steel members or other shaped steel members 52 are placed on the top 35 of the casing 30, a center hole jack 54 is attached on top of the multiple shaped steel members 52, and the tension member 11 is pulled upward in the X3 direction using the center hole jack 54 to separate the existing pile 10 from the surrounding ground.

[0032] This hip cutting can prevent construction problems such as the bottom end of the existing pile 10 being pulled up coming into close contact with the ground below it, preventing the edge from breaking with the ground below (the surrounding ground), making it difficult to pull up the pile. If the existing pile 10 is not in close contact with the surrounding ground, the hip cutting shown in the illustration is not necessary, but even in this case, the existing pile 10 can be pulled up with the center hole jack 54 to check whether hip cutting is necessary or not (the above is step A).

[0033] 7, the structure gripping band 60 is lowered by a crane CR, suspended in the X4 direction to the top end 35 of the casing 30, and installed on the top end 35. Here, the installation position of the structure gripping band 60 may be on any construction base surface set in addition to the top end of the casing 30.

[0034] Here, as shown in Figure 8, the structure gripping band 60 has two half bands 62, and the fixing flanges 64 at both ends of each half band 62 are placed opposite each other, and a ring-shaped structure gripping band 60 is formed by inserting bolt nuts 69 into bolt holes 64a opened on both bands.

[0035] A plurality of gripping elastic members 68 are attached to an inner wall surface 66 of the half-split band 62, and the plurality of gripping elastic members 68 grip the upper portion of the casing 30 inserted therein. Here, hard rubber or the like can be used as the gripping elastic member (this is the end of step B).

[0036] 9, a separate tension member 14 extending upward from the top end of the existing pile 10 is connected to the pressing machine 20 so as to be able to be lifted, and the feed cylinder 27 and the main winch 29 are driven to lift the separate tension member 14, thereby lifting the existing pile 10 upward in the X5 direction. Here, in this initial lifting, the upper part of the tension member 11 embedded in the existing pile 10 may be extended from the top end of the existing pile 10, and the tension member 11 may be lifted by the pressing machine 20.

[0037] As shown in Figure 10, which is an enlarged view of portion X in Figure 9, the upper end of a tension member 11 inserted into the inside of the existing pile 10 is connected to the lower part of a mechanical joint 13 (coupler) located near the top end 12 of the existing pile 10, and the lower end of a separate tension member 14 is connected to the upper part of the mechanical joint 13, and this separate tension member 14 is pulled up by a pressing machine 20.

[0038] As shown in Figures 9 and 10, the existing pile 10 is pulled up above the structure gripping band 60 until it protrudes a predetermined length (for example, about 1 m to several meters), and then the structure gripping band 60 attached to the top end 35 of the casing 30 is tightened to grip the existing pile 10 temporarily.

[0039] 11 and 12, which are enlarged views of part XII of the figure, a cutting line CL that defines a removal area (range of height t1) at a position t2 above the gripping point by the structure gripping band 60 is cut by a wire saw W. By this cutting, the blocks in the removal area at a range of height t1 above the existing pile 10 are removed (this is process C).

[0040] As shown in Figures 9 and 10, the existing pile 10 is pulled up to a predetermined length, the existing pile 10 is temporarily supported by being gripped by the structure gripping band 60, the cutting line CL is cut by the wire saw W as shown in Figures 11 and 12, the new top end resulting from the cutting is chipped off to expose the head of the tension member 11, a mechanical joint 13 (see Figure 10) is attached to the head of the tension member 11, a separate tension member 14 (see Figure 10) is connected to the mechanical joint 13, the separate tension member 14 is supported by the press-in machine 20, the grip of the existing pile 10 by the structure gripping band 60 is released, and the separate tension member 14 is pulled up by the press-in machine 20. This is the construction D step, and the existing pile 10 is removed by repeating the D step. Here, the existing pile 10 may be pulled up by a separate lifting machine such as a crane in addition to the press-in machine 20.

[0041] After the existing piles 10 are removed, as shown in Fig. 13, a hammer grab HG is attached to the press-in machine 20, and the hammer grab HG is used to dredge and drill the bottom of the casing 30. The soil generated by drilling is collected in a vessel V behind the press-in machine 20 and transported outside the site.

[0042] Next, as shown in FIG. 14, the casing 30 is pulled up partway in the X6 direction by the pressing machine 20, and the casing 30 is gripped and supported by a casing gripping band 90 on the ground, and the backfill material 82 is backfilled into the cavity 72 created by pulling the casing 30 up partway.

[0043] Here, the casing gripping band 90 may be a repurposed structure gripping band 60 .

[0044] Here, as shown in FIG. 15, a jack 38 is placed on top of the casing gripping band 90, and a pushed-up material 39 is attached to the upper region of the casing 30 above the casing gripping band 90. In addition to pulling up the casing 30 with the pressing machine 20, an auxiliary construction method may be applied in which the casing is pulled up by pushing up the pushed-up material 39 with the jack 38.

[0045] By applying this auxiliary construction method, even if the pulling force of the press-in machine 20 is insufficient when pulling up the casing 30, the casing 30 can be pulled up without having to separately prepare a press-in machine with higher performance.

[0046] By repeatedly pulling up the casing 30 halfway, holding and temporarily supporting it with the casing holding band 90, and filling the cavity 72 formed by pulling up the casing 30 with backfilling material 82, the removal of the casing 30 and the filling of the cavity 70 created by the removal of the casing 30 with backfilling material 80 are completed, as shown in Figure 16 (this is the end of process E).

[0047] According to the method for removing an existing structure shown in the figure, even when an existing structure 10 buried underground is to be removed under headroom restrictions, there is no need to prepare large-scale, special equipment, and the existing structure 10 can be removed efficiently.

[0048] In addition, the present invention is not limited to the configuration shown here, and may be implemented in other embodiments in which other components are combined with the configurations and the like of the above-mentioned embodiment. In this regard, the present invention may be modified within the scope of the gist of the present invention, and may be appropriately determined according to the application form. [Explanation of symbols]

[0049] 10: Existing structures (existing piles, cast-in-place concrete piles) 11: Tensile member (PC steel bar) 12: Top edge 13: Mechanical coupling 14: Separate tension member 20: Pressing machine (BG excavator) 21: Base Machine 23: Mast 25: Rotary drive 27: Feed cylinder 29: Main winch 30: Casing 31: Short casing 35: Top 38: Jack 39: Pushed up material 40: Ruler steel plate 42: Guide opening 45: Stepping 52: Shaped steel material 54: Center hole jack 60: Structure holding band 62: Half Band 64: Fixed flange 64a: Bolt hole 66: Inner wall 68: Gripping elastic material 69: Bolts and nuts 70,72: hollow 80, 82: Backfill material 90: Casing holding band G: Ground (underground) L: Liner plate B: Backhoe K:Kamaba C: Coring machine S: Sand pump H1, H2: Hose P:Plant CL: Cutting line W: Wire saw HG: Hammer Glove V: Vessel

Claims

1. Process A includes attaching a tension member to an existing structure buried underground, and isolating the existing structure from the ground by using a press-in machine to press a casing between the existing structure and the surrounding ground; A step B of installing a structure holding band for supporting the existing structure on the top end of the casing or on a construction base on the ground; A process C of pulling up the tension member with the press-in machine or a separate lifting machine, passing the existing structure through the inside of the structure gripping band, gripping the existing structure with the structure gripping band and supporting it on the casing or the construction base, and cutting and removing a removal area of ​​the existing structure that is above the gripping point by the structure gripping band; and a D process of chipping off a new top end of the existing structure resulting from the cutting to expose a head of the tension member and connecting it to a separate tension member, supporting the separate tension member on the press-in machine or the separate lifting machine, releasing the grip of the existing structure by the structure gripping band, lifting the separate tension member with the press-in machine or the separate lifting machine, passing the existing structure inside the structure gripping band, gripping the existing structure with the structure gripping band and supporting it on the casing or the construction base, and cutting and removing a removal area of ​​the existing structure that is above the gripping point by the structure gripping band. A method for removing an existing structure, comprising repeating step D to remove the existing structure.

2. 2. The method for removing an existing structure as described in claim 1, characterized in that in step A, a center hole jack is attached directly or indirectly to the top end of the casing, and the hip cutting of the existing structure is performed using the center hole jack.

3. 3. The method for removing an existing structure according to claim 1 or 2, wherein in step A, a ruler steel plate having a guide opening for guiding the press-in of the casing is installed prior to the press-in of the casing.

4. The method further includes a step E of pulling out and removing the casing, 3. A method for removing an existing structure as described in claim 1 or 2, characterized in that the casing is pulled up halfway, the casing is gripped and supported by a casing gripping band on the ground, the cavity created by pulling the casing up halfway is backfilled with backfill material, and this set of pulling the casing up halfway, gripping it, and backfilling it with backfill material is repeated.

5. The method for removing an existing structure described in claim 4, characterized in that in step E, a jack is placed on the casing gripping band, a pushed-up material is attached to an upper region of the casing above the casing gripping band, and in addition to lifting the casing with the pressing machine or a separate lifting machine, the casing is lifted by pushing up the pushed-up material with the jack.

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