Prefabricated pile installation method, and prefabricated pile reinforcement structure

Abstract

To reinforce a head of a prefabricated pile while ensuring the workability of a prefabricated pile.SOLUTION: A prefabricated pile installation includes steps of: sinking a prefabricated pile having a cylindrical cross section, in which a bag body capable of being filled with a hardening material is attached to part of an inner surface of a pile head with a space formed between the other part of an inner surface and the bag body, into a pile hole in which soil cement is stored; filling the bag body with the hardening material while the prefabricated pile is sunk into the pile hole, inflating the bag body and bringing the bag body into contact with the entire circumference of the inner surface to fix the bag body to the pile head; and hardening the hardening material filled in the bag body.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a construction method for a precast pile and a reinforcing structure for a precast pile. [Background technology]

[0002] Patent document 1 describes a construction method for burying a hollow precast pile into the ground, in which the inner surface of the precast pile is pressed in the outward radial direction while the precast pile is penetrated into the ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-177103 A Summary of the Invention [Problem to be solved by the invention]

[0004] A common construction method for pile foundations using precast piles with a cylindrical cross section is the pre-boring method. In this construction method, if the head of the precast pile is filled with concrete or the like in advance to reinforce the precast pile, the workability of the precast pile when sinking it deteriorates. In addition, in the case of precast piles with a cylindrical cross section, it is desirable to reinforce the head of the pile, which is likely to be a weak point in the pile foundation structure.

[0005] The object of the present disclosure is to reinforce the head of a precast pile while ensuring the workability of the precast pile. [Means for solving the problem]

[0006] The construction method of a precast pile in the first embodiment is characterized by comprising the steps of: sinking a precast pile having a cylindrical cross-section, in which a bag body capable of being filled with a hardening material is attached to a part of the inner surface of the pile head with a space formed between the other part of the inner surface and the bag body, into a pile hole in which soil cement is stored; filling the bag body with a hardening material while the precast pile is sunk into the pile hole, inflating the bag body and bringing the bag body into contact with the entire circumference of the inner surface to fix the bag body to the pile head; and hardening the hardening material filled in the bag body.

[0007] According to the above-mentioned embodiment, a prefabricated pile having a cylindrical cross section, in which a bag body is attached to a part of the inner circumferential surface of the pile head and a space is formed between the other part of the inner circumferential surface and the bag body, is sunk into a pile hole in which soil cement is stored. In this way, a space is formed between the other part of the inner circumferential surface of the prefabricated pile and the bag body, and the soil cement passes through this space when the prefabricated pile is sunk. This ensures ease of construction.

[0008] Furthermore, with the precast pile sunk in the pile hole, the bag is filled with a hardening material to expand the bag, and the bag is brought into contact with the entire inner periphery of the head of the precast pile, thereby fixing the bag to the head. Then, the hardening material filled in the bag is hardened. This reinforces the head of the precast pile. In this way, the workability of the precast pile is ensured, and the head of the precast pile can be reinforced.

[0009] The precast pile installation method according to the second aspect is the precast pile installation method according to the first aspect, characterized in that an expandable metal mesh is provided on the outer peripheral surface of the bag body.

[0010] According to the above-mentioned embodiment, an expandable metal mesh is provided on the outer circumferential surface of the bag body, so that when the bag body expands, the metal mesh is sandwiched between the bag body and the inner circumferential surface of the precast pile, and the bag body can be fixed more firmly to the head of the precast pile than when no metal mesh is provided.

[0011] The reinforcing structure for a precast pile in the third aspect is characterized in that it comprises a bag body that is attached to a part of the inner surface of the pile head of a precast pile having a cylindrical cross-section, with a space formed between the bag body and another part of the inner surface, and into which a hardening material can be filled, and a hardening material that is filled into the bag body, thereby inflating the bag and contacting the entire circumference of the inner surface of the pile head of the precast pile, thereby fixing the bag body to the pile head and hardening in the filled state.

[0012] According to the above aspect, the bag, which can be filled with a hardening material, is attached to a part of the inner circumferential surface of the head of the prefabricated pile having a cylindrical cross section, and in this state, a space is formed between the bag and the other part of the inner circumferential surface. As a result, when the prefabricated pile is sunk into the pile hole in which the soil cement is stored, the soil cement passes through the space between the bag and the other part of the inner circumferential surface, ensuring workability.

[0013] Furthermore, when the precast pile is sunk in the pile hole, the inside of the bag is filled with hardening material, which inflates the bag and brings the bag into contact with the entire inner periphery of the head of the precast pile, thereby fixing the bag to the head. With the bag fixed to the head, the hardening material is hardened. In this way, the workability of the precast pile is ensured, and the head of the precast pile can be reinforced. Effect of the Invention

[0014] According to the present disclosure, it is possible to reinforce the head of a precast pile while ensuring the workability of the precast pile. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a schematic diagram showing a construction machine used in the precast pile construction method according to the first embodiment of the present disclosure. [Diagram 2] 1A, 1B, and 1C are process diagrams showing each step of a precast pile construction method according to the first embodiment of the present disclosure. [Diagram 3] 1A, 1B, and 1C are process diagrams showing each step of a precast pile construction method according to the first embodiment of the present disclosure. [Figure 4]1A and 1B are a side cross-sectional view and a plan cross-sectional view showing a reinforcement structure for a precast pile according to the first embodiment of the present disclosure. [Diagram 5] 1A, 1B, and 1C are process diagrams showing main steps of a precast pile construction method according to the first embodiment of the present disclosure. [Figure 6] FIG. 11 is a side cross-sectional view showing a reinforcement structure for a precast pile according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] First Embodiment An example of a construction method for a precast pile according to a first embodiment of the present disclosure and a reinforcing structure for a precast pile will be described with reference to Fig. 1 to Fig. 5. Note that arrow H shown in each figure indicates the up-down direction, i.e., the vertical direction, arrow W shown in each figure indicates the width direction perpendicular to arrow H and also the horizontal direction, and arrow D shown in each figure indicates the depth direction perpendicular to arrows H and W and also the horizontal direction.

[0017] (Overall composition) [Construction machinery used to construct prefabricated piles 10] At the construction site where the precast pile 10 is constructed, as shown in FIG. 1, a pile driver (excavator) 20, a drilling fluid mixer (not shown), a cement milk plant 22, a generator 24, a water tank 26, and a silo 28 are installed.

[0018] The pile driver 20 includes a pile driver body 20a, a mast 20b, and a motor 20c. The pile driver body 20a is self-propelled, and a mast 20b is attached to the pile driver body 20a, and a motor 20c is attached to the mast 20b so as to be movable up and down. Furthermore, a swivel 20d and a drill 20e are connected to the motor 20c.

[0019] The pile driver 20 is also equipped with a generator 20f for supplying power to the motor 20c, and the drilling drill 20e is rotated by the driving force of the motor 20c. Meanwhile, the drilling drill 20e has an internal flow path, and drilling fluid and cement milk (pile periphery fixing fluid and foot protection fluid) are supplied to the internal flow path of the drilling drill 20e from a drilling fluid mixer and a cement milk plant 22 via a swivel 20d. The drilling fluid and cement milk supplied to the internal flow path are discharged from the tip (lower end) of the drilling drill 20e.

[0020] [Outline of construction method of prefabricated pile 10] The precast pile 10 to be constructed is a cylindrical precast concrete pile. First, the construction method of the precast pile 10 will be outlined, and the main part of the construction method will be described later.

[0021] 2(A) and (B), the drilling drill 20e is rotated to excavate the ground, thereby forming a pile hole 30. Specifically, the pile hole 30 is formed so as to penetrate the intermediate layer M of the ground and reach the supporting layer S.

[0022] In addition, in the root reinforcement liquid injection / stirring / mixing process shown in Figure 2(C), the root reinforcement liquid is supplied to the pile hole 30 while the root reinforcement liquid and the excavated soil are stirred and mixed to generate soil cement S02 that will become the root reinforcement portion inside the pile hole 30.

[0023] Furthermore, in the pile periphery fixing liquid injection / stirring / mixing process shown in Figure 3(A), the pile periphery fixing liquid is supplied to the pile hole 30 while the pile periphery fixing liquid and the excavated soil are stirred and mixed to generate soil cement S01 that will become the pile periphery fixing portion in the pile hole 30, while the drilling drill 20e is pulled up.

[0024] 3(B) and (C), in the precast pile installation process, the precast pile 10 is installed in the pile hole 30 in which the soil cements S01 and S02 are stored by the pile driver 20 (see FIG. 1). Then, the soil cement S01 overflows from the pile hole 30.

[0025] (Main part configuration) Next, the reinforcing structure 100 for the precast pile 10 and a construction method for the main parts of the precast pile 10 will be described.

[0026] [Reinforcement structure 100 for prefabricated pile 10] The reinforcement structure 100 includes a bag body 12 (see FIG. 4) and concrete 34 (see FIG. 5) filled into the bag body 12. Concrete is an example of a hardening material.

[0027] 4(A) and (B) show the head of a precast pile 10 before it is sunk. As shown in Fig. 4(A) and (B), a bag body 12 is attached to the inner peripheral surface 10a of the head of the precast pile 10. This bag body 12 is made of a woven fabric made of synthetic fibers, and can be filled with concrete 34.

[0028] Specifically, the bag body 12 is formed to have a cylindrical shape extending in the vertical direction in an expanded state filled with concrete 34, and the bag body 12 in an unexpanded state before expansion is attached to a part of the inner circumferential surface 10a of the prefabricated pile 10 by a fixing member (not shown). A space 10b is formed between the bag body 12 in an unexpanded state and the other part of the inner circumferential surface 10a. Furthermore, one end of an injection pipe 14 for injecting concrete 34 into the inside of the bag body 12 is connected to the upper end of the bag body 12.

[0029] In this configuration, when concrete 34 is filled into the bag body 12 in the unexpanded state through the injection pipe 14, the bag body 12 expands to the expanded state. Then, the outer circumferential surface of the bag body 12 in the expanded state is pressed against the entire circumference of the inner circumferential surface 10a, and the bag body 12 is fixed to the pile head (see FIG. 5(C)). No space is formed between the bag body 12 in this expanded state and the inner circumferential surface 10a.

[0030] [Construction method for main parts of prefabricated pile 10] Next, a construction method for changing the unexpanded bag body 12 into the expanded state will be described by specifying the outlined construction method for the precast pile 10 described above.

[0031] First, as shown in Figures 4(A) and (B), before the precast pile 10 is sunk, the bag body 12 in an unexpanded state is attached to the inner peripheral surface 10a of the pile head of the precast pile 10. Then, in the precast pile sinking process shown in Figure 5(A), the precast pile 10 is sunk into the pile hole 30 in which the soil cement S01 is stored. When sinking the precast pile 10, the soil cement S01 passes through the space 10b between the bag body 12 in an unexpanded state and the other part of the inner peripheral surface 10a. This ensures ease of construction.

[0032] 5(A), (B), and (C), concrete 34 is injected into the bag body 12 in the unexpanded state through the injection pipe 14 to fill it, thereby displacing the soil cement S01 stored in the space 10b and expanding the bag body 12. The outer circumferential surface of the expanded bag body 12 then comes into contact with and is pressed against the entire circumference of the inner circumferential surface 10a, and the bag body 12 is fixed to the head of the precast pile 10. No space is formed between the bag body 12 in the expanded state and the inner circumferential surface 10a.

[0033] Then, the concrete 34 filled inside the bag body 12 hardens, thereby reinforcing the head of the precast pile 10. The injection pipe 14 is detached from the bag body 12 after the process of exposing the head of the precast pile 10.

[0034] (summary) As described above, in the construction method for the precast pile 10 and the reinforcing structure 100 for the precast pile 10, the bag body 12 in an unexpanded state is attached to a part of the inner circumferential surface 10a of the precast pile 10. A space 10b is formed between the bag body 12 in an unexpanded state and the other part of the inner circumferential surface 10a. As a result, when the precast pile 10 is sunk into the pile hole 30 in which the soil cement S01 is stored, the soil cement S01 passes through the space 10b between the bag body 12 and the other part of the inner circumferential surface 10a, ensuring workability.

[0035] Furthermore, after the precast pile 10 is sunk into the pile hole 30, the bag 12 attached to the pile head is filled with concrete 34, and the bag 12 is inflated to fix it to the pile head of the precast pile 10. Furthermore, with the bag 12 fixed to the pile head, the filled concrete 34 is hardened. In this way, the pile head of the precast pile 10 can be reinforced while ensuring the workability of the precast pile 10.

[0036] <Second embodiment> An example of a construction method for a precast pile according to a second embodiment of the present disclosure and a reinforcement structure for a precast pile will be described with reference to Fig. 6. Note that, regarding the second embodiment, differences from the first embodiment will be mainly described.

[0037] In the construction method for the precast pile 10 and the reinforcing structure 110 for the precast pile 10 according to the second embodiment, as shown in Fig. 6, an expandable metal mesh 50 is attached to the outer circumferential surface of the bag body 12. This expandable metal mesh 50 is arranged along the outer circumferential surface of the bag body 12 whether the bag body 12 is in a non-deployed state or in a deployed state, and is adapted to follow the deformation of the outer circumferential surface of the bag body 12.

[0038] In this configuration, when the bag body 12 is in the expanded state, the metal mesh 50 is sandwiched between the bag body 12 and the inner peripheral surface 10a of the precast pile 10. This allows the bag body 12 to be more firmly fixed to the pile head of the precast pile 10 compared to a case in which the metal mesh 50 is not provided.

[0039] Although the present disclosure has been described in detail with respect to a specific embodiment, it is clear to a person skilled in the art that the present disclosure is not limited to the embodiment, and various other embodiments are possible within the scope of the present disclosure. For example, in the above embodiment, the precast pile 10 is a cylindrical precast concrete pile, but it may be a cylindrical steel pipe pile.

[0040] In addition, although not specifically described in the above embodiment, in order to firmly fix the bag body 12 to the inner surface 10a of the pile head of the prefabricated pile 10, a comb-shaped plate member may be attached to the inner surface 10a of the pile head.

[0041] Furthermore, in the above embodiment, the concrete 34 is used as an example of the hardening material, but other hardening materials may be used. [Explanation of symbols]

[0042] 10 Prefabricated piles 10a Inner surface 10b space 12 Bag body 30 Pile hole 34 Concrete (an example of a hardening material) 50 Metal Mesh 100 Reinforcement structure 110 Reinforcement structure S01 Soil cement

Claims

1. A process of sinking a prefabricated pile having a cylindrical cross section, in which a bag capable of being filled with a hardening material is attached to a part of the inner peripheral surface of the pile head and a space is formed between the other part of the inner peripheral surface and the bag, into a pile hole in which soil cement is stored; a step of filling the bag with a hardening material to expand the bag while the prefabricated pile is sunk in the pile hole, thereby bringing the bag into contact with the entire periphery of the inner circumferential surface and fixing the bag to the pile head; A step of hardening the hardening material filled in the bag; A method for constructing prefabricated piles comprising the steps of:

2. A stretchable metal mesh is provided on the outer periphery of the bag body. A method for constructing a precast pile according to claim 1.

3. A bag body that is attached to a part of an inner peripheral surface of a pile head of a prefabricated pile having a cylindrical cross section, and a space is formed between the bag body and another part of the inner peripheral surface, and the bag body can be filled with a hardening material. a hardening material that is filled inside the bag, expands the bag, and contacts the bag with the entire inner circumferential surface of the pile head of the prefabricated pile, fixing the bag to the pile head and hardening in the filled state; A reinforcement structure for prefabricated piles.

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