Method for preventing the buoyancy and sinking of piles and a device for preventing buoyancy and sinking used therein.

Abstract

The present invention provides a method for preventing piles from floating or sinking, and a device for preventing the floating or sinking of piles, which can prevent changes in the depth position of a pile when the burial work is interrupted and no external force is applied to the buried pile. [Solution] When the pile driving work by the pile driving machine 10 is interrupted, a state occurs where no external force is applied to the lower pile 20a which is in the buried state. In such a case, with the lower pile 20a inserted through the anti-sway device 17 of the pile driving machine 10, a detachable anti-buoyancy device 30 is attached to the lower pile 20a so as to contact the anti-sway device 17 above, below, or both of the anti-sway device 17. If the lower pile 20a tries to float up or sink, the anti-buoyancy device 30 will contact the anti-sway device 17, preventing a change in its depth position.

Description

Technical Field

[0001] The present invention relates to a method for preventing the sinking and floating of piles and a sinking and floating prevention tool used therefor.

Background Art

[0002] When constructing a structure on soft ground, a pile foundation is provided to stably support the structure. In order for the tip of the pile foundation to reach the support layer below the soft ground, it is necessary to arrange it at a predetermined depth and embed it while managing the depth position. If the pile foundation in the embedded state sinks by itself and the depth position changes, it will hinder the management of the depth position. Therefore, when constructing a foundation pile, it is necessary to prevent the self-sinking of the foundation pile. Therefore, in the open-cut method, which is one of the construction methods of pile foundations, it has been proposed to prevent the self-sinking of the foundation pile by providing a hired pile on the pile head of the foundation pile (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As construction methods for foundation piles, various construction methods according to the state of the ground, the scale of the structure, etc. are known, and some of them connect a plurality of piles into one foundation pile. In that construction method, it is necessary to connect the piles to each other. In such a construction method of connecting a plurality of piles, the embedding work using a pile driver is interrupted during the connection work between the piles, and an external force is not applied to the piles in the embedded state. When the ground is soft, there is a risk that the piles in the embedded state will sink by themselves. Therefore, it is necessary to prevent the self-sinking of the piles for depth management of the piles.

[0005] However, since other piles are connected to the buried piles, it is not possible to install the aforementioned hierarchical piles, and therefore the technology to prevent self-settling cannot be applied. In addition, depending on the ground conditions, such as the presence of groundwater, buried piles may float up rather than settle on their own. Therefore, in order to manage the depth of the piles, it is necessary to address not only self-settling piles but also floating piles.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a method for preventing the floating and sinking of piles and a device for preventing floating and sinking of piles used therein, which can prevent the piles from floating up or sinking and changing their depth position when the burial work is interrupted and no external force is applied to the buried piles. [Means for solving the problem]

[0007] To achieve the above objective, the present invention is: A method for preventing a pile from floating up, sinking, or both of the above, which occurs when a pile is embedded in the ground using a pile driver, and the embedding work by the pile driver is interrupted, thereby eliminating external force on the embedded pile. The pile driving machine is equipped with a sway-preventing device that prevents the pile from swaying during its installation, With the buried pile inserted into the anti-sway device, a detachable anti-buoyancy device is attached to the buried pile above, below, or both of the anti-sway device so as to come into contact with the anti-sway device. [Effects of the Invention]

[0008] According to the present invention, if there is a risk of a buried pile sinking, a buoyancy prevention device is attached above the anti-sway device. This prevents the pile from sinking and changing its depth position, as the buoyancy prevention device attached above the anti-sway device will contact the anti-sway device even if the pile attempts to sink. Furthermore, if there is a risk of a buried pile floating up, a buoyancy prevention device is attached below the anti-sway device. This prevents the pile from floating up and changing its depth position, as the buoyancy prevention device attached below the anti-sway device will contact the anti-sway device even if the pile attempts to float up. If there is a risk of both sinking and floating up, buoyancy prevention devices are attached both above and below the anti-sway device. This prevents the pile from changing its depth position due to both factors. When resuming pile driving work with a pile driver, the attached buoyancy prevention devices can be removed so that they do not interfere with the driving work. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram showing a pile driver with a lower pile attached. [Figure 2] A diagram illustrating the procedure for burying steel pipe piles while using a method to prevent the piles from floating or sinking. [Figure 3] A perspective view showing a device to prevent buoyancy. [Figure 4] A perspective view showing how the anti-buoyancy device is attached to the steel pipe pile in its open position. [Figure 5] A perspective view showing another example of a buoyancy control device. [Figure 6] A plan view showing another example of a buoyancy control device. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the pile buoyancy prevention method and buoyancy prevention device used therein according to the present invention will be described with reference to the drawings. In this embodiment, the pile buoyancy prevention method and buoyancy prevention device according to the present invention are applied when constructing a steel pipe pile construction method. The steel pipe pile construction method is a method that is generally known in which a foundation pile is formed by connecting a plurality of steel pipe piles, including a steel pipe pile with an expanding wing at its lower end.

[0011] First, we will briefly describe the pile driving machine used to embed steel pipe piles in the ground in the steel pipe pile construction method. As shown in Figure 1, the pile driving machine 10 comprises a base machine 11 and a leader 12. The leader 12 is provided in front of the base machine 11 so as to be able to move up and down. When the leader 12 is upright, it extends vertically and is supported by a stay 13 that connects the base machine 11 and the leader 12. The leader 12 is equipped with a rotary drive device 14 (hydraulic auger 14) that moves up and down along the leader 12 by a drive source (not shown).

[0012] The hydraulic auger 14 is equipped with a hydraulic motor 15 and a rod cap 16. The hydraulic motor 15 is the drive source that rotates the rod cap 16. The rod cap 16 is detachably attached to the upper end of the buried steel pipe pile 20, and when the steel pipe pile 20 is installed, it is configured to rotate together with the rod cap 16 by the drive of the hydraulic motor 15. Therefore, by rotating the steel pipe pile 20 with the hydraulic auger 14 and lowering the hydraulic auger 14 along the leader 12, the steel pipe pile 20 is rotated and pressed into the ground.

[0013] When the steel pipe pile 20 is driven in by rotation, a vibration-preventing device 17 is provided at the lower end of the leader 12 to prevent the steel pipe pile 20 from tilting or becoming misaligned. The vibration-preventing device 17 is designed to be openable and closable, and when closed, an insertion hole 18 is formed. During rotational driving, the steel pipe pile 20 is inserted with a gap between the inner surface of the insertion hole 18 and the outer surface of the steel pipe pile 20, thereby preventing vibration.

[0014] The steel pipe pile 20 shown in Figure 1 is the lowest of the multiple steel pipe piles 20 that make up the foundation pile (referred to as the lower pile 20a), and has an expanding wing 21 and an excavation bit 22 at its lower end.

[0015] Next, the procedure for embedding foundation piles using the steel pipe pile method, performed with the pile driving machine 10, will be explained. A method and device for preventing the piles from floating or sinking will be used in this construction. Here, we will assume the case where two steel pipe piles 20 are connected to form a foundation pile, but there are also cases where three or more steel pipe piles 20 are connected to form a foundation pile.

[0016] First, with the vibration damping device 17 of the pile driver 10 open, the lower pile 20a, which has expanding wings 21 and a drilling bit 22 at its lower end, is set in the pile driver 10, and the vibration damping device 17 is closed to insert the lower pile 20a into the insertion hole 18. This state is shown in Figure 1. Then, the hydraulic auger 14 is rotated (for example, clockwise) by the hydraulic auger 14 while the hydraulic auger 14 is lowered along the leader 12. As a result, the lower pile 20a is embedded in the ground, as shown in Figure 2(a). During the embedding of the lower pile 20a, the depth at which the lower pile 20a is embedded is controlled. This is the first step.

[0017] Next, the hydraulic auger 14 is removed from the lower pile 20a and raised as shown in Figure 2(b). At this time, since the hydraulic auger 14 has been removed from the lower pile 20a, no external force is applied to the lower pile 20a, and there is nothing to receive any external force. Therefore, if the lower pile 20a is left as is, there is a risk that it may sink on its own due to reasons such as soft ground. In such cases, with the lower pile 20a still inserted through the insertion hole 18 of the anti-vibration device 17, the anti-buoyancy device 30 is attached to the lower pile 20a above the anti-vibration device 17. At this time, the anti-buoyancy device 30 is made to contact the upper surface of the anti-vibration device 17. As a result, even if the lower pile 20a tries to sink on its own, the anti-buoyancy device 30 attached to the lower pile 20a will contact the anti-vibration device 17, thus preventing the lower pile 20a from sinking and changing its depth.

[0018] Also, if the hydraulic auger 14 is left removed from the lower pile 20a, in some cases, the lower pile 20a may float due to reasons such as the ground containing groundwater. In such a case, as shown by the phantom line in Fig. 2(b), with the lower pile 20a inserted through the insertion hole 18 of the anti-floating device 17, the anti-floating and sinking prevention tool 30 is attached to the lower pile 20a below the anti-floating device 17. At this time, the anti-floating and sinking prevention tool 30 is made to abut against the lower surface of the anti-floating device 17. Thereby, even if the lower pile 20a tries to float, the anti-floating and sinking prevention tool 30 attached to the lower pile 20a abuts against the anti-floating device 17, preventing the lower pile 20a from floating and changing its depth position.

[0019] If there is a risk of both self-sinking and floating, the anti-floating and sinking prevention tool 30 is attached to the lower pile 20a both above and below the anti-floating device 17. Thereby, it is possible to prevent the lower pile 20a from self-sinking or floating and changing its depth position. Whether the anti-floating and sinking prevention tool 30 is provided above, below or both of the anti-floating device 17 is arbitrarily selected according to the state of the ground where the steel pipe pile 20 is embedded.

[0020] With the self-sinking, floating or both of the lower pile 20a thus prevented, the operation of connecting another steel pipe pile 20 (referred to as the upper pile 20b) to the lower pile 20a is carried out. In this case, as shown in Fig. 2(b), the upper end portion of the upper pile 20b is attached to and suspended from the rod cap 16 of the hydraulic auger 14. Then, as shown in Fig. 2(c), the hydraulic auger 14 is lowered to align the lower end portion of the upper pile 20b with the upper end portion of the lower pile 20a, and the two are connected using welding or fixtures, etc., to integrate the lower pile 20a and the upper pile 20b. The above process carried out after the first process becomes the second process.

[0021] In the subsequent third step, the anti-buoyancy device 30 attached to the lower pile 20a is removed, and then the integrated lower pile 20a and upper pile 20b are rotated by the hydraulic auger 14 while the hydraulic auger 14 is lowered along the leader 12. As a result, the lower pile 20a and upper pile 20b are rotated and pressed into the ground, as shown in Figure 2(d). Here as well, the depth at which the lower pile 20a and upper pile 20b are buried is controlled, and the construction of one foundation pile is completed when both piles 20a and 20b are buried to a predetermined depth.

[0022] Furthermore, when three or more steel pipe piles 20 are connected to form a foundation pile, the second and third steps described above will be repeated.

[0023] Next, we will describe the anti-buoyancy device 30 used in the embedding construction of the foundation piles as described above. As shown in Figure 3, the anti-buoyancy device 30 has a pair of arc-shaped members 31 and an inner member 32.

[0024] The pair of arc-shaped members 31 are made of a curved strip of steel plate having a uniform thickness. The thickness of each arc-shaped member 31 is, for example, several mm to about 10 mm. The pair of arc-shaped members 31 are combined to form an annular shape. In this case, the inner diameter is set to be larger than the outer diameter of the steel pipe pile 20. When the pair of arc-shaped members 31 are combined to form an annular shape, a hinge 33 is provided on one of the two opposing ends of the pair of arc-shaped members 31, and a snap lock 34 is provided on the other.

[0025] The pair of arc-shaped members 31 are permanently connected and integrated by a hinge 33. Furthermore, the pair of arc-shaped members 31 can be opened and closed using the hinge 33 as a pivot point, and when closed, the entire structure forms a ring. In the closed state, the ends of the pair of arc-shaped members 31 are fastened together by a snap lock 34, thereby maintaining the closed state. As shown in Figure 4, by releasing the snap lock 34, the pair of arc-shaped members 31 are opened using the hinge 33 as a pivot point.

[0026] The inner member 32 is formed from an elastic material such as hard rubber, and is a curved strip-shaped elastic material with a uniform thickness. The thickness of the inner member 32 is about the same as the thickness of the arc-shaped member 31, for example, a few millimeters to 10 millimeters. The inner member 32 is attached to almost the entire arc-shaped inner surface 31a of each arc-shaped member 31. When the pair of arc-shaped members 31 are closed to form an annular shape, the arc-shaped inner surface 32a of the inner member 32 forms the annular inner surface 35. The thickness of the inner member 32 is set so that the diameter of the circle formed by the annular inner surface 35 is smaller than the outer diameter of the steel pipe pile 20. In other words, the thickness of the inner member 32 is formed to be thicker than the gap between the arc-shaped inner surface 31a of the arc-shaped member 31 and the outer surface of the steel pipe pile 20.

[0027] The pair of arc-shaped members 31 correspond to the combined member, and the arc-shaped inner surface 32a of the inner member 32 corresponds to the arc-shaped inner surface in this invention. When the pair of arc-shaped members 31 are closed and combined to form an annular inner surface 35 on the inside of the anti-buoyancy device 30, this corresponds to the annular inner surface formation state. On the other hand, when the pair of arc-shaped members 31 are open, this corresponds to the annular inner surface non-formation state. The hinge 33 and the snap lock 34 correspond to the state-changing member, and the snap lock 34 corresponds to the fastener.

[0028] The anti-buoyancy device 30 having the above configuration is attached to and detached from the steel pipe pile 20 in the following manner.

[0029] As shown in Figure 4, the snap lock 34 is released to open the pair of arc-shaped members 31, and the pair of arc-shaped members 31 are closed so that they sandwich the steel pipe pile 20. Then, the snap lock 34 is tightened to hold the closed state. Since the annular inner surface 35 of the anti-buoyancy device 30 is set to a size smaller than the outer diameter of the steel pipe pile 20, tightening the snap lock 34 causes the anti-buoyancy device 30 to be pressed against the steel pipe pile 20. Due to the frictional force between the annular inner surface 35 and the outer surface of the steel pipe pile 20 and this pressing force, the anti-buoyancy device 30 is firmly attached to the steel pipe pile 20. To remove the anti-buoyancy device 30, simply release the snap lock 34 and open the pair of arc-shaped members 31. In this way, the anti-buoyancy device 30 is configured to be detachable.

[0030] According to the method for preventing the buoyancy and sinking of steel pipe piles 20 and the buoyancy prevention device 30 used therein, as described above, the following effects can be obtained.

[0031] (1) In the steel pipe pile construction method, in which multiple steel pipe piles 20 are connected to form a foundation pile, it is necessary to connect the steel pipe piles 20 to each other and integrate them, and during this work, the burying work by the pile driving machine 10 is interrupted. As a result of this interruption, a situation arises in which no external force is applied to the buried steel pipe piles 20, or there is no object to receive the external force applied to the steel pipe piles 20.

[0032] In such cases, if there is a risk of the steel pipe pile 20 sinking while being buried, attaching the anti-buoyancy device 30 to the steel pipe pile 20 above the sway-stopping device 17 will prevent the steel pipe pile 20 from sinking and changing its depth. Also, if there is a risk of the steel pipe pile 20 floating up while being buried, attaching the anti-buoyancy device 30 to the steel pipe pile 20 below the sway-stopping device 17 will prevent the steel pipe pile 20 from floating up and changing its depth. If there is a risk of both sinking and floating up, attaching the anti-buoyancy device 30 to the steel pipe pile 20 both above and below the sway-stopping device 17 will prevent the steel pipe pile 20 from changing its depth while being buried. When resuming the burying work of the steel pipe pile 20 by the pile driver 10, the attached anti-buoyancy device 30 can be removed so that the anti-buoyancy device 30 does not interfere with the burying work.

[0033] (2) Since the anti-buoyancy device 30 is attached to the steel pipe pile 20 in a state of being pressed against it, the anti-buoyancy device 30 can be securely fixed to the steel pipe pile 20. As a result, when the steel pipe pile 20 tries to sink or rise, the anti-buoyancy device 30 that is in contact with the anti-sway device 17 will not be displaced by that force, and sinking or rising can be reliably prevented.

[0034] (3) The anti-buoyancy device 30 has an inner member 32 made of an elastic material such as hard rubber, which is provided inside a pair of arc-shaped members 31, and an annular inner surface 35 is formed by the inner member 32 that contacts the outer surface of the steel pipe pile 20. As a result the steel pipe pile 20 is pressed against by the elastic inner member 32, it is possible to prevent the outer surface of the steel pipe pile 20 from being damaged and affecting its strength.

[0035] (4) By changing the thickness of the inner member 32 of the anti-buoyancy device 30, the pair of arc-shaped members 31 connected by a hinge 33 and equipped with a snap lock 34 can be used on other steel pipe piles 20 with different outer diameters, thereby increasing their versatility.

[0036] (5) When the pair of arc-shaped members 31 form an annular shape, the pair of arc-shaped members 31 are permanently connected by a hinge 33 provided on one of the opposing parts where the ends of the pair of arc-shaped members 31 face each other. This makes it possible to carry and manage the anti-buoyancy device 30 as a single device, thus making it easy to carry and manage the anti-buoyancy device 30. In addition, it can be easily attached to and detached from the steel pipe pile 20 by operating a fastener such as a snap lock 34 provided on the other of the pair of opposing parts.

[0037] Furthermore, the embodiment is not limited to the above-described embodiment; for example, the following form may also be used.

[0038] (a) Among the construction methods for installing foundation piles, if the method involves connecting multiple piles to form a single foundation pile, the method for preventing the buoyancy of the pile using the buoyancy prevention device 30 may be applied to other construction methods, not limited to the steel pipe pile method.

[0039] (b) In the steel pipe pile construction method, a break may be taken after removing the hydraulic auger 14 from the lower pile 20a, or the work for the day may be ended when the hydraulic auger 14 is removed from the lower pile 20a, and the work may be continued the following day. In such cases, when the lower pile 20a remains detached from the pile driving machine 10 for a longer period of time, it is more preferable to adopt the pile floating and sinking prevention method of this embodiment.

[0040] (c) Other fasteners besides the snap lock 34 may be used. As an example, a configuration using a bolt B and a nut N can be considered, as shown in the alternative fastener 40 in Figure 5. In this case, outwardly protruding pieces 41 are provided at the end of each arc-shaped member 31 on the side where the fastener is attached, and these protruding pieces 41 are connected to each other with a bolt B and a nut N. This fastens the ends of the pair of arc-shaped members 31 together.

[0041] (d) As shown in the alternative fastener 50 in Figure 6, when a pair of arc-shaped members 31 are combined to form an annular shape, fasteners may be provided on both of the two opposing ends of the pair of arc-shaped members 31. Note that the fastening configuration shown in Figure 6 fastens the projections 51 together with a bolt B and a nut N. In this case, the fasteners provided on both opposing ends correspond to the state-changing members.

[0042] (e) Instead of forming an annular ring with a pair of arc-shaped members 31, the annular ring may be formed by connecting multiple arc-shaped members 31. Furthermore, the combination does not have to be such that it forms an annular ring when combined with a pair of arc-shaped members 31; it is sufficient to have a combination member having an arc-shaped inner surface 31a that forms an annular ring when combined. For example, a combination member may have an arc-shaped inner surface 31a formed on one side of a rectangular member.

[0043] (f) The inner members 32 provided on the arc-shaped inner surface 31a of each arc-shaped member 31 may not be a single strip-shaped member covering substantially the entire arc-shaped inner surface 31a, but may be provided in a divided state.

[0044] (g) A configuration may be adopted in which circumferentially extending protrusions are formed on the arc-shaped inner surface 31a of a pair of arc-shaped members 31, and the inner member 32 is omitted. In this case, the inner diameter dimension formed by the protruding ends of the protrusions is set to be slightly smaller than the outer diameter dimension of the steel pipe pile 20. This makes it possible to create a state in which the anti-buoyancy device 30 is pressed against the steel pipe pile 20 by the protrusions biting into the steel pipe pile 20 when the anti-buoyancy device 30 is attached to the steel pipe pile 20. [Explanation of Symbols]

[0045] 10...Pile driver, 14...Hydraulic auger (rotary drive device), 20...Steel pipe pile, 21...Expanding wing, 30...Anti-buoyancy device, 31...Arch-shaped member (combination member), 32...Inner member, 32a...Arch-shaped inner surface, 33...Hinge (state-changing member), 34...Snap lock (fastener, state-changing member), 35...Annular inner surface.

Claims

1. A method for preventing a pile from floating up, sinking, or both of the buried pile, which occurs when the burying work by the pile driver is interrupted and external force is no longer applied to the buried pile, is provided for use when burying a pile in the ground using a pile driver. The pile driving machine is equipped with a sway-preventing device that prevents the pile from swaying during its installation, A method for preventing a pile from floating or sinking, comprising inserting the buried pile into the anti-sway device, and then attaching a detachable anti-buoyancy device to the buried pile above, below, or both of the anti-sway device so as to contact the anti-sway device.

2. A method for preventing the floating and sinking of a pile according to claim 1, applicable to a steel pipe pile construction method in which a foundation pile consisting of multiple steel pipe piles connected together is embedded in the ground, In addition to the aforementioned anti-sway device, the pile driver is equipped with a rotary drive device that moves up and down vertically. The aforementioned steel pipe pile construction method is, The first step involves attaching the upper end of a steel pipe pile, which has expanding wings at its lower end, to the rotary drive device and burying the steel pipe pile while rotating it, The second step involves removing the rotary drive device from the buried steel pipe pile and raising it, attaching the upper end of the connected steel pipe pile to the rotary drive device, and then connecting the upper end of the buried steel pipe pile to the lower end of the connected steel pipe pile to integrate the two piles. A third step involves burying the integrated steel pipe pile while rotating it, It is equipped with, A method for preventing a pile from floating or sinking, wherein the state in which no external force is applied by the pile driving machine occurs in the second step, and in the second step, the floating / sinking prevention device is attached to the buried steel pipe pile.

3. A buoyancy prevention device used in the method for preventing the buoyancy and sinking of a pile according to claim 1 or 2, Multiple combined members having an arc-shaped inner surface, A state-changing member that can switch between a state in which an annular inner surface is formed by the arc-shaped inner surfaces of each of the plurality of combined members, and a state in which an annular inner surface is not formed, Equipped with, A buoyancy prevention device that, when attached to a pile in the buried state with the aforementioned annular inner surface formed, is pressed against the pile.

4. The annular inner surface has a larger diameter than the outer diameter of the pile in the buried state. The anti-buoyancy device according to claim 3, wherein each of the plurality of combined members is provided with an inner member having a thickness greater than the gap dimension between its inner surface and the outer surface of the buried pile.

5. The anti-buoyancy device according to claim 4, wherein the inner member is an elastic material such as hard rubber.

6. The aforementioned combination members are provided in pairs, The buoyancy control device according to claim 3, wherein the state-changing member is a hinge provided on one of the two opposing portions where the ends of the pair of combined members face each other, and a fastener provided on the other.

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