JP2013060774A - Pull-out method for underground pile and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of securely and efficiently pulling out a foundation pile through simple and continuous operation irrelevantly to the outer diameter of the pile without having any special gripping structure for pile.SOLUTION: A casing 7 is pressed in an outer circumference of a foundation pipe 2 buried in the ground by fluidizing the soil through injection of high-pressure water into an outer periphery and exciting operation. Sludge produced by the fluidization is discharged onto the ground from a through hole at an upper part of the casing 7. After vibration is stopped and the casing 7 is stopped at a predetermined position in the ground, the foundation pile 2 is held with sediment solidified by the fluidization. The casing 7 is pulled up onto the ground and extracted while the foundation pile 2 is held in this state. After the casing is pulled out onto the ground, the foundation pile 2 is discharged from the casing 7 by performing the exciting operation again.

Description

  The present invention relates to a method and an apparatus for extracting an underground pile buried in the ground. More specifically, the present invention relates to a drawing method and an apparatus for drawing out an existing underground pile such as a foundation pile buried in the ground through a casing excavation operation.

  In general, when a structure such as an existing construction is dismantled for some reason, the foundation pile, which is an existing pile supporting these, is pulled out and removed together with the dismantling of the facilities on the ground. When the ground such as a general residential area is soft and the burial depth of the pile is shallow, it is possible to pull it out by grasping the head of the existing pile peeping on the ground with a heavy machine and lifting it. However, it is difficult for piles whose ground is hard and deeply buried. For example, existing piles used for river piers, etc. and existing piles used for the grounds of large constructions cannot be easily pulled out as described above.

  For this reason, various techniques for facilitating this extraction have been developed and implemented. The construction method generally used is a construction method that makes the ground around existing piles flexible and easy to pull out. For this purpose, a construction method is adopted in which the periphery of the pile is surrounded by a casing and the ground in the casing is excavated by jetting high-pressure jet water. In this manner, the existing piles are pulled out after handmade to make it easy to pull out the ready-made piles.

  The conventional method for pulling out piles is, for example, while excavating in the soil a casing in which a nozzle for supplying high-pressure water to the ground surrounding the foundation pile buried in the ground is excavated. A technique is known in which compressed air is ejected and the soil is fluidized to reduce the resistance in the soil due to the ground on the outer periphery of the foundation pile, and the foundation pile is pulled out (see, for example, Patent Document 1). Pulling out in this case is a method of excavating by applying vibration without rotating the casing, but is a method of holding and lifting the lower end of the pile after detecting the position of the lower end of the foundation pile after excavation.

  Further, as another example, a technique is known in which the casing is dug while rotating so as to wrap the existing pile, the outer periphery of the existing pile is chucked with a chucking device, and the casing is pulled up together with the existing pile (for example, Patent Documents) 2 and 3). In this case, the pile is gripped by forcibly operating gripping means such as gripping claws for chucking. Furthermore, the casing embedded concentrically with the pile drives the casing while applying vibration with a vibration generator, digs the ground, pulls up only the casing, and then connects the pile to the head of the pile by connecting the wire A technique for lifting by a crane is also known (for example, see Patent Document 4).

JP 2002-81066 A JP-A-8-165649 JP 2001-3362 A JP 2003-155747 A

  As described above, a technique for pulling out a pile using a casing is known. However, although the conventional method gives the casing a rotational motion or gives vibration, when holding and pulling the pile, the gripping operation is forcibly performed by a chucking device attached to the casing. There is a need. Moreover, the method of detecting the lower end part of a pile after excavation with a casing and grasping the lower end part of a pile requires installation of a detection means and also requires electrical control.

  All of these techniques are forcibly applying a gripping force from the outside or accompanied by control. In addition, since the gripping device that requires operation is attached to the casing that digs into the ground, the gripping device itself is prone to trouble when the device is in the soil, and the gripping itself may lack stability. It was. In addition, the method of pulling up the pile after pulling up the casing is accompanied with a slinging work for changing the wire rope from the casing side to the pile side, and is a work such as re-hanging the wire rope of the crane, which is not efficient.

  In any case, the excavation of the casing, the lifting and holding of the pile, and the lifting require operations in separate processes, and the continuity of work is interrupted. The present invention has been made to solve the above-described problems, and achieves the following object. An object of the present invention is to provide an underground pile drawing method and apparatus capable of pulling up a foundation pile with a simple structure and capable of efficiently and efficiently pulling up a foundation pile in a short time.

The present invention takes the following means in order to achieve the object.
The pulling method of the underground pile of the present invention 1
The process of moving to the position of the existing pile (2) buried in the ground and excavating the ground on the outer periphery of the existing pile (2) by vibrating the casing (7) arranged on the outer periphery of the existing pile (2) When,
At the same time as applying the vibration, from the nozzle (12) provided on the outer periphery of the casing (7), spraying high-pressure water onto the soil below the casing (7) to fluidize the soil;
Holding the existing pile (2) by solidifying the soil in the fluidized casing (7) after stopping the vibration and stopping the casing (7) at a predetermined depth in the ground;
A step of pulling up the casing (7) holding the existing pile (2) together with earth and sand in the casing (7) to the ground and pulling out the existing pile (2) from the ground;
The casing (7) pulled up to the ground is vibrated, the holding of the earth and sand in the casing (7) and the existing pile (2) is canceled, and the existing pile (2) is discharged out of the casing (7). Process.

The method of pulling out the underground pile of the present invention 2 is the present invention 1,
An auxiliary rod-shaped auxiliary member (16) for preventing the earth and sand from falling is disposed at the lower part of the casing (7), and the auxiliary member (16) is a rocking member that swings freely only upward in the vertical direction. It has a dynamic operation function and is characterized by holding the foundation pile (2).

The method for pulling out underground piles of the present invention 3 in the present invention 1,
The casing (7) has a plurality of through holes (19) at the upper part on the outer periphery, and the mud water in the casing (7) is discharged out of the casing (7) through the through holes (19). It is characterized by becoming.
The method for pulling out underground piles of the present invention 4 in the present invention 1,
The casing (7) is lifted by a movable crane (5).

The underground pile pulling device of the present invention 5
A casing (7) having a plurality of through holes (19) for excavating the ground on the outer periphery of the existing pile (2) by excavating the ground on the outer periphery of the existing pile (2) embedded inside with a hollow inside When,
A vibration exciter (8) provided on an upper part of the casing (7) for applying vibration to the casing (7);
A nozzle (12) provided in the lower part of the casing (7), for injecting and fluidizing high-pressure water into the excavation-side soil by supply from the high-pressure water supply device (13, 14);
An outer peripheral surface of the existing pile (2) which is provided in the casing (7) via a support (17) and has a swing operation function which swings freely only in the vertical direction under the restriction of the stopper (17a). And a plurality of auxiliary members (16) in contact with.

  The underground pile pulling method and apparatus according to the present invention is a pulling device having a simple structure, and the pulling process of the pile can be performed in a short time. It is not limited to the size of the target pile, it is not necessary to dig around the entire pile length, there is no need to detect the lower end of the pile, and there is no need to forcibly clamp the pile. is there. Although the present invention is not essential, the auxiliary pile is provided so that the foundation pile can be gripped only by the reciprocation of the casing accompanying the vibration. As a result, a plurality of foundation piles can be pulled up continuously in a short time, and the lifting efficiency is improved.

FIG. 1 is an overall view showing an underground pile extracting device. FIG. 2 is a cross-sectional view showing details of the casing. FIG. 3 is a process diagram showing a state immediately before excavation of the casing. FIG. 4 is a process diagram showing a state where the casing is excavated to a predetermined position in the ground. FIG. 5 is a process diagram showing a state in which the casing holds the foundation pile and is pulled up to the ground. FIG. 6 is a process diagram showing a state in which the foundation pile is discharged from the casing lifted on the ground.

  An embodiment of an underground pile drawing method and its apparatus according to the present invention will be described in detail with reference to the drawings. The scope of application of the present invention is not limited to the method of drawing underground piles, but is mainly implemented at construction sites such as residential areas and river construction sites. Hereinafter, in this Embodiment, it demonstrates as an example applied to removal of the foundation pile used for the foundation of the bridge over the river. FIG. 1 is an example of an underground pile extraction device (system) 1 and shows an overall configuration of an apparatus for extracting a foundation pile 2 after a bridge pier laid in a river is removed.

  The foundation pile 2 is a foundation pile that has supported the structure left in the soil after the above-ground structure is removed, that is, an existing pile. This foundation pile 2 must be removed for newly constructed structures and the like. In the case of this example, the temporary bridge 3 is extended from the shore to the foundation pile 2 side of the river, the temporary bridge 3 is installed, the underground pile extraction device 1 is arranged on the temporary bridge 3 and the removal work is performed. It is. On this temporary bridge 3, a crawler crane 4 for lifting the foundation pile 2 is installed. A wire rope 6 is wound around the tip of the crawler type mobile crane 4 via a crane 5 to suspend a casing 7.

  A vibratory hammer 8 as a vibration device is disposed and fixed on the casing 7, and the wire rope 6 suspends the vibratory hammer 8, and the casing 7 is also indirectly suspended. This vibro hammer 8 is a known vibration device that vibrates the casing 7 in the vertical direction, and a drive device 9 such as a hydraulic unit is installed in the vicinity thereof to vibrate the casing 7 in the vertical direction (vertical direction). Is.

  On the other hand, as shown in FIG. 2, the casing 10 is provided with a pipe 10 for supplying high-pressure jet water to the outer wall thereof, and the tip of the pipe 10 is disposed in the opening 11 which is the lower end of the casing 7. The nozzle 12 which injects water is attached to this front-end | tip. The jet pump device 13 for producing the high-pressure water is installed on the temporary bridge 2, and accompanying this, the pump 14 immerses the suction port so as to be submerged in the river water and pumps up the water. The pump 14 is a submersible pump driven by an electric motor, and is driven by electricity generated by a generator 15 installed on the temporary bridge 3. The jet pump device 13, the pipe 10, the nozzle 12, the pump 14 and the like constitute a high-pressure jet injection device.

  The jet pump device 13 is for converting the river water taken in from the pump 14 into high-pressure jet water. In this manner, river water is used as a high-pressure pressurized water by the jet pump device 13 and supplied to the nozzle 12 via the hose and the pipe 10. The spray water from the nozzle 12 fluidizes the soil around the opening 11 as the casing 7 digs. The casing 7 is provided with an auxiliary member 16 on the inner wall near the opening 11.

  The auxiliary member 16 is a rod-like or plate-like member, and is arranged at four equiangular intervals along the inner diameter circumference of the casing 7 so that it can swing in the excavation direction. Each auxiliary member 16 is supported on a support body 17 fixed to the inner wall of the casing 7 so as to be swingable by a swing shaft 18. One end of the auxiliary member 16 is rocked in a direction including the central axis of the casing 7 while being regulated by the support body 17 and is not rocked downward from the horizontal state. It has become. That is, the auxiliary member 16 swings by an angle of 90 degrees upward from the horizontal state within the inner hole of the casing 7.

  That is, the support body 17 is provided with a stepped portion (stopper) 17a to restrict the auxiliary member 16 from moving downward. When the foundation pile 2 relatively moves (in the direction of the central axis) and passes through the casing 7, as shown in FIG. 2, the head of the foundation pile 2 hits the auxiliary member 16 and the auxiliary member 16 swings. Then the end is lifted up like a two-dot chain line. When the foundation pile 2 passes through the casing 7, the tip of the auxiliary member 16 is maintained in contact with the outer peripheral surface of the foundation pile 2.

  That is, when the foundation pile 2 enters the casing 7, the auxiliary member 16 maintains the foundation pile 2 during relative movement. However, when the foundation pile 2 relatively moves downward from the casing 7, the end of the auxiliary member 16 is in frictional contact with the foundation pile 2. That is, after the foundation pile 2 is taken into the casing 7, the foundation pile 2 cannot move out of the casing 7 and remains held. The auxiliary member 16 has a lever shape, and swings freely only in an upward direction indicated by an arrow (see FIG. 2) around a swing shaft 18 provided on the support body 17. Note that the auxiliary member 16 is not for holding the casing 7, but for holding the fall of the earth and sand in the ground that has been solidified by liquefaction and compacted as a result of liquefaction. Is.

  Further, as described above, the nozzles 12 are arranged and fixed at four positions at equiangular positions on the outer peripheral surface of the lower end portion of the casing 7. The injection directions of the nozzles 12 are arranged toward the center line (casing center line) in the excavation direction. From this nozzle 12, the water pumped up by the pump 14 is jetted as high-pressure water through the pipe 10. The jetted water fluidizes the ground near the opening 11 of the casing 7. This fluidization promotes the excavation of the casing 7. With the promotion of the casing 7, the fluidized ground sediment remains between the foundation pile 2 and the casing 7, mud is brought upward, and heavy sediment is retained downward.

  Further, a plurality of drain ports (through holes) 19 are formed in the upper pipe wall of the casing 7, and a part 20 of the muddy water fluidized in the casing 7 is passed through the discharge port 19 to the casing 7. Can be discharged to the outside. Further, when the casing 7 digs into the ground and reaches a predetermined position, when a part of the discharge port 19 of the casing 7 reaches the head position of the foundation pile 2, the foundation pile 2 is removed from the discharge port 19. It can be confirmed visually. Therefore, the discharge port 19 has a function as a confirmation window for the foundation pile 2.

  The underground pile extraction device 1 on the temporary bridge 3 is basically configured as described above. All devices are easy to move. Since multiple foundation piles 2 exist on one pier and are submerged at the river level, when starting construction work, surround the pile 2 with sheet pile steel and drain the water inside. It is carried out. The foundation pile 2 is pulled out for each individual pile. Since water is drained at the time of drawing, the worker can work near the pile even in a river. The casing 7 is arranged at a predetermined position while being hung by the crane 5 and the wire rope 6 on the upper part of the foundation pile 2 to be pulled out.

[Drilling with casing 7]
Next, the casing 7 is dug up and the foundation pile 2 is pulled up. The construction method will be described with reference to FIGS. FIG. 3 shows a process immediately before excavation in which the casing 7 is installed and positioned on the foundation pile 2. Although the upper part is omitted in FIG. 3, the casing 7 corresponds to one foundation pile 2 as described above and is suspended by the crane 5. Subsequently, the casing 7 is dug into the ground as shown in FIG.

  In this case, the vibro hammer 8 is activated and vibrates the casing 7. At the same time, high-pressure water is ejected from the nozzle 12 disposed at the lower end of the casing 7 into the ground. When the casing 7 reaches the foundation pile 2, as shown in FIG. 4, the auxiliary member 16 in a horizontal state comes into contact with the head of the foundation pile 2 and swings and tilts. The auxiliary member 16 and the foundation pile 2 move relative to each other while maintaining the contact state along. The earth and sand of the excavated ground is fluidized by the jet of high-pressure water and stays between the casing 7 and the foundation pile 2. At this time, the soil having a large specific gravity and light moisture is discharged from the discharge port 19 of the casing 7. Excavation proceeds while sand with relatively high specific gravity in the earth and sand is volumetric at the bottom.

  The excavation of the casing 7 is promoted by fluidization. Even if the diameters of the foundation piles 2 are different, they can pass within the swing range of the auxiliary member 16 in the casing 7 as long as the pile diameter is smaller than the casing inner diameter. Therefore, even if there are variations in the outer diameter and length of the foundation pile 2, it is possible to continue the excavation without being limited without any measurement. When the casing 7 digs up to a predetermined position as shown in FIG. 4, the vibration operation by the vibro hammer 8 is stopped, and at the same time, the injection of high-pressure water from the nozzle 12 is also stopped. However, the nozzle 12 may be clogged with earth and sand, and a small amount of water is ejected in actual construction.

[Grip of foundation pile 2]
A part 20 of muddy water having a light specific gravity is discharged from the discharge port 19 of the casing 7. When the casing 7 stops at a predetermined position, the head of the foundation pile 2 can be confirmed from the discharge port 19. Part of the muddy water 20 is discharged from the discharge port 19 due to the stop of the casing 7, but other earth and sand remain while being held by the auxiliary member 16 between the casing 7 and the foundation pile 2. In this state, the casing 7 is subsequently pulled up as shown in FIG. The materials (soil, gravel, sand, fine particles, clay) that mainly make up the earth and sand will solidify in the casing 7. However, even if the auxiliary member 16 is not provided, the earth and sand in the casing 7 does not fall.

  A large amount of high-pressure water jet from the nozzle 12 is supplied. At this time, when the earth and sand material contains a large amount of sand and gravel, the vibration operation by the vibro hammer 8 is applied to the soil in the casing 7 in the case of sand ground having a high groundwater level in the event of an earthquake. As a result, a phenomenon such as a liquefaction phenomenon occurs. Due to the liquefaction phenomenon, water such as muddy water is discharged from the upper part, whereby sand having a relatively high specific gravity sinks and becomes denser and hardened. When the vibration of the vibro hammer 8 is stopped when this liquefaction phenomenon occurs, moisture is released into the casing 7 and the sand is densely packed and compacted, that is, there are few gaps between particles. Only the sand and gravel will remain. The compacted and solidified sand and gravel hold the foundation pile 2 from the outer peripheral surface like a chuck. That is, since the surface of the foundation pile 2 that is generally an existing pile is rough, the foundation pile 2 is held by the frictional force between the compacted sand and the outer periphery of the foundation pile 2. Become.

  At the same time, a force that bites the foundation pile 2 in a wedge shape is generated in the auxiliary member 16 by the pulling operation when the casing 7 is pulled up. Therefore, the auxiliary member 16 grips the foundation pile 2 at the time of pulling up. Since the surface of the foundation pile 2 is rough, the auxiliary member 16 is configured to easily bite into the foundation pile 2 due to the wedge effect. Moreover, since each of the four auxiliary members 16 operates freely, the gripping force is reinforced by the frictional force individually following the surface shape of the foundation pile 2. In addition, since the earth and sand are in a state where the mound is not heavy and has a heavy specific gravity, it stays over the entire length of the foundation pile 2 in the casing 7, so that the foundation pile 2 and the casing are affected by friction and pressure with the sand and gravel in the earth and sand. 7 will be integrated.

  In addition, even if there is no auxiliary member 16, it has the function to hold the foundation pile 2 without the earth and sand falling outside the casing 7 when the foundation pile 2 is pulled up. Accordingly, the main function of the auxiliary member 16 is not the gripping of the foundation pile 2 by frictional force but the function of preventing the earth and sand in the casing 7 from collapsing and falling. When the casing 7 is lifted to the ground with such a configuration, the configuration shown in FIG. 5 is obtained. That is, when the casing 7 is dug up and reaches a predetermined position, the casing 7 is pulled up as it is, so that the foundation pile 2 can be grasped by the solidified earth and sand and the auxiliary member 16 as shown in the drawing and completely pulled out. When the outer diameters of the foundation piles 2 are different, the swing angle of the auxiliary member 16 is different, but it can be pulled out mainly by the frictional force of sand and gravel of the earth and sand described above.

[Release of gripping foundation pile 2]
For example, when the casing 7 pulled up to the ground is subjected to an excitation operation in a state where the lower end of the foundation pile 2 is in contact with the ground surface, as shown in FIG. And discharged from the casing 7 together with earth and sand. According to this configuration, there is no need to perform operations such as holding and changing the casing 7 and the foundation pile 2. Thus, after discharging the foundation pile 2 and earth and sand from the casing 7, the casing 7 becomes empty and becomes the state shown in FIG.

  The earth and sand in the casing 7 is discharged and the auxiliary member 16 returns to the original horizontal state. Subsequently, the casing 7 is moved to the position of the foundation pile 2 remaining in the undrawn state, the same operation is repeated, and the foundation pile 2 is pulled out. As described above, the operator only moves and aligns the casing 7 to the position of the remaining foundation pile 2. The pulled-out foundation pile 2 is lifted on the temporary bridge 3 and transported to a storage place by a truck or the like.

  As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to this form, and can change within the range which does not deviate from the objective of this invention and the meaning. For example, in the above-described embodiment, the object to be pulled out is the foundation pile 2, but the foundation pile 2 may be any type of pile such as a wooden pile, a concrete pile, and a steel pipe pile. Moreover, since it can apply also to steel sheet piles (sheet pile) etc. other than a pile, the pile as used in the present invention is not limited to piles, such as a narrow foundation pile.

DESCRIPTION OF SYMBOLS 1 ... Underground pile extraction device 2 ... Foundation pile 3 ... Temporary bridge 5 ... Crane 6 ... Wire rope 7 ... Casing 8 ... Vibro hammer 12 ... Nozzle 13 ... Jet pump device 16 ... Auxiliary member 17 ... Support 18 ... Swing Shaft 19 ... Drain port

Claims (5)

The process of moving to the position of the existing pile (2) buried in the ground and excavating the ground on the outer periphery of the existing pile (2) by vibrating the casing (7) arranged on the outer periphery of the existing pile (2) When,
At the same time as applying the vibration, from the nozzle (12) provided on the outer periphery of the casing (7), spraying high-pressure water onto the soil below the casing (7) to fluidize the soil;
Holding the existing pile (2) by solidifying the soil in the fluidized casing (7) after stopping the vibration and stopping the casing (7) at a predetermined depth in the ground;
A step of pulling up the casing (7) holding the existing pile (2) together with earth and sand in the casing (7) to the ground and pulling out the existing pile (2) from the ground;
The casing (7) pulled up to the ground is vibrated, the holding of the earth and sand in the casing (7) and the existing pile (2) is canceled, and the existing pile (2) is discharged out of the casing (7). A method for drawing underground piles. In the underground pile extraction method according to claim 1,
An auxiliary rod-shaped auxiliary member (16) for preventing the earth and sand from falling is disposed at the lower part of the casing (7), and the auxiliary member (16) is a rocking member that swings freely only upward in the vertical direction. An underground pile pulling method characterized by having a dynamic operation function and holding the foundation pile (2). In the underground pile extraction method according to claim 1,
The casing (7) has a plurality of through holes (19) at the upper part on the outer periphery, and the mud water in the casing (7) is discharged out of the casing (7) through the through holes (19). A method for drawing underground piles, characterized by In the underground pile extraction method according to claim 1,
The casing (7) is lifted by a movable crane (5). A casing (7) having a plurality of through holes (19) for excavating the ground on the outer periphery of the existing pile (2) by excavating the ground on the outer periphery of the existing pile (2) embedded inside with a hollow inside When,
A vibration exciter (8) provided on an upper part of the casing (7) for applying vibration to the casing (7);
A nozzle (12) provided in the lower part of the casing (7), for injecting and fluidizing high-pressure water into the excavation-side soil by supply from the high-pressure water supply device (13, 14);
An outer peripheral surface of the existing pile (2) which is provided in the casing (7) via a support (17) and has a swing operation function which swings freely only in the vertical direction under the restriction of the stopper (17a). A plurality of auxiliary members (16) in contact with the underground pile extracting device.

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