JP6987559B2 - Construction method of continuous underground wall and steel pipe pile - Google Patents

Description

The present invention relates to a method for constructing a continuous underground wall formed by connecting piles made of a solidifying material such as concrete to each other in the ground, and a steel pipe pile used for constructing the continuous underground wall.

Conventionally, it has been known to construct a continuous underground wall underground or underground as a method of constructing a structure at a construction site. It is also known to construct a continuous underground wall as a water blocking wall.
In the conventional method of constructing a continuous underground wall, for example, excavation holes are excavated in the ground at predetermined intervals to fill the inside with concrete, and when these concretes are semi-hardened and become self-supporting, other excavations are performed during that time. Holes are excavated and filled with concrete and overlapped with each other to build a continuous underground wall. In order to prevent the excavation hole from collapsing, a casing is installed at the entrance to fill the excavation hole with bentonite liquid or the like.

Further, in the method for constructing a waterproof wall described in Patent Document 1, a hole is drilled by a casing, earth and sand in the casing are discharged into the ground, and a steel pipe pile is built in the casing. By injecting the solidifying material into the hole and pulling out the casing to form a solidifying material ring, a pile having a double structure is used as a leading pile and placed at a predetermined interval. Further, a continuous underground wall is formed by forming a trailing pile so as to wrap the solidifying material ring between the leading piles.

In the method for constructing a continuous underground wall described in Patent Document 2, a bottomed tubular body for water blocking with a casing attached is inserted into a vertical hole excavated in soft ground, and the bottomed tubular body is cured through the bottomed tubular body. The filler is filled in the vertical hole to form a double-structured waterproof pile. Then, a continuous underground impermeable wall is formed so that the adjacent waterproof piles overlap each other at the portion of the curable filler. The casing is pulled up, leaving the curable filler provided on the outer peripheral surface of the water-stopping bottomed cylinder.
Moreover, the curable filler between the adjacent waterproof piles is agitated by the spiral stirring member provided on the outer peripheral surface of the water-stopping bottomed tubular body, and after the spiral stirring member is pulled up, the curable filler is used. It is hardened to build a continuous underground wall.

Japanese Unexamined Patent Publication No. 2001-96060 Japanese Unexamined Patent Publication No. 2012-237138

By the way, the bentonite liquid is pumped up and reprocessed together with the construction of the continuous underground wall, but the bentonite generated by the reprocessing is discarded as industrial waste, which has an adverse effect on the environment.
Further, the method of constructing the continuous underground wall described in Patent Documents 1 and 2 requires a casing, a spiral stirring member, etc. in addition to the steel pipe, and has a drawback that it is troublesome and costly due to a large number of work man-hours. there were.

Therefore, the present invention has been made in view of the above-mentioned circumstances, does not generate industrial waste with treatment, does not have a double structure in the pile body, and can be constructed with a small number of work man-hours and low cost. It is an object of the present invention to provide a method of constructing a continuous underground wall as described above and a steel pipe pile used in this construction method.

The method for constructing a continuous underground wall according to the present invention includes a steel pipe placing process in which the first steel pipe and the second steel pipe are continuously and alternately placed along the construction direction, and the first steel pipe and the second steel pipe are placed. The excavation process of excavating the inside of the first steel pipe and the second steel pipe while or after placing, and the first of pulling out the first steel pipe while filling or filling the solidifying material in the first steel pipe arranged every other pipe. Filling in the solidifying material filling step and the filling in the first solidifying material filling step by the claws protruding to the outside of the second steel pipe while filling or filling the solidifying material in the second steel pipe arranged between the first steel pipes. It is characterized by comprising a second solidifying material filling step of pulling out a second steel pipe while disturbing the solidified material.
According to the present invention, from the first steel pipe and the second steel pipe that are continuously cast, the solidified material is disturbed by the claws of the second steel pipe between the piles of the solidified material from which the first steel pipe is pulled out. By pulling out, it is possible to form a continuous underground wall in which piles of solidifying material are connected to each other. Therefore, it is possible to construct a continuous underground wall in which piles made of solidifying material are integrated with each other with a small number of man-hours. Moreover, it is possible to prevent the solidified material from collapsing during construction and to prevent the generation of industrial waste because bentonite or the like is not used.

The method for constructing a continuous underground wall according to the present invention includes a first steel pipe placing step in which the first steel pipe is placed at intervals along the construction direction, and a first steel pipe placing step while or after the first steel pipe is placed. (1) The first excavation step of excavating the inside of the steel pipe, the first solidifying material filling step of pulling out the first steel pipe while filling or filling the first steel pipe with the solidifying material, and the second steel pipe between the first steel pipes. The second steel pipe placing process to be placed, the second excavation step to excavate the inside of the second steel pipe while driving or after placing the second steel pipe, and filling or filling the solidifying material in the second steel pipe. It is characterized by comprising a second solidifying material filling step of pulling out the second steel pipe while disturbing the solidifying material filled in the first solidifying material filling step by the claw portion protruding to the outside of the second steel pipe.
According to the present invention, the solidifying material is pulled out from the solidifying material while disturbing the solidifying material by the claws of the second steel pipe that is driven later between the piles of the solidifying material from which the first steel pipe was driven earlier. It is possible to form a continuous underground wall by connecting the piles of the above.

The method for constructing a continuous underground wall according to the present invention includes a second steel pipe placing step in which a second steel pipe is placed at intervals along the construction direction, and a second steel pipe placing step while or after placing the second steel pipe. (2) The second excavation process for excavating the inside of the steel pipe, the first steel pipe placing process for placing the first steel pipe between the second steel pipes, and the inside of the first steel pipe while or after placing the first steel pipe. The first excavation step of excavating, the first solidifying material filling step of pulling out the first steel pipe while filling or filling the first steel pipe, and filling or filling the solidifying material in the second steel pipe. It is characterized by comprising a second solidifying material filling step of pulling out the second steel pipe while disturbing the solidifying material filled in the first solidifying material filling step by the claw portion protruding to the outside of the second steel pipe.
According to the present invention, the first steel pipe is driven between the second steel pipes having the previously driven claws, and the first steel pipe is solidified by the claws of the second steel pipe between the piles of the solidifying material from which the first steel pipe is pulled out. By pulling out from the solidifying material while disturbing the material, it is possible to form a continuous underground wall in which piles of the solidifying material are connected to each other.

Further, it is preferable that the claw portion is provided at a position where it does not interfere with the first steel pipe when the second steel pipe is placed.
By driving the second steel pipe into the first steel pipe previously driven by press-fitting or rocking press-fitting, the claw portion can be driven at a position that does not interfere with the first steel pipe.

Further, it is preferable that the claw portion of the second steel pipe is provided in the gap between one circumscribed line of the first steel pipe and / or the second steel pipe or two opposing circumscribed lines on both sides and the adjacent first steel pipe.
Even when the continuous underground wall is constructed at a position close to the existing structure, the second steel pipe can be placed by positioning the claw portion between the circumscribed line and the adjacent first steel pipe.

Further, the second steel pipe provided with the claw portion may be driven by press-fitting, rotary press-fitting or rocking press-fitting.
The second steel pipe can be driven by selecting either press-fitting, rotary press-fitting, or rocking press-fitting so that the claws do not interfere with each other due to the hardness of the ground and the relationship with the first steel pipe.

Further, when the second steel pipe is pulled out, it is preferable that the solidified material filled in the first solidifying material filling step is in a state from the condensation start time to the condensation end time.
If the solidified material filled in the first solidifying material filling step is in a state from the setting start time to the setting ending time, it flows by being disturbed by the claws of the second steel pipe and is solidified filled in the second solidifying material filling step. Can be integrated with the material by stirring.

Further, it is preferable that the claw portion of the second steel pipe can be expanded and contracted outward.
By reducing the diameter of the claw portion when placing the second steel pipe, it can be press-fitted smoothly without interfering with the first steel pipe that was previously placed. Further, when the second steel pipe is pulled out, the solidifying material of the first steel pipe can be disturbed and integrated by enlarging the diameter of the claw portion.

Further, when the second steel pipe is pulled out, it is preferable to replenish the new solidifying material while disturbing the solidifying material filled in the first solidifying material filling step by the claw portion.
By replenishing the solidified material disturbed by the claw portion of the second steel pipe with a new solidified material, it is possible to reinforce the connecting portion between the solidified materials and assist the integration.

Further, a press-fitting machine may be installed in the first steel pipe and / or the second steel pipe, and the first steel pipe and the second steel pipe may be driven and pulled out by the press-fitting machine.
By installing the press-fitting machine in the first steel pipe and / or the second steel pipe, it is possible to perform press-fitting and pulling out by taking reaction force on the first steel pipe and the second steel pipe, and hitting without using the surrounding ground as a scaffold. Since it can move on the installed first steel pipe and second steel pipe, it can be constructed even on slopes and rough ground.

In addition, after installing the PC steel wire in the excavated first steel pipe and / or the second steel pipe and fixing the first solidified material corresponding to the first steel pipe and / or the second solidified material corresponding to the second steel pipe. The PC steel wire may be strained to introduce prestress.
By introducing prestress in the first pile and / or the second pile constituting the continuous underground wall by the post-tension method, the tensile stress applied to the continuous underground wall can be controlled.

In addition, the first steel pipe and the second steel pipe are pulled out in the ground region, and the first solidified material and the second solidified material are disturbed at the claws, and the first steel pipe and the second steel pipe are held in water without being pulled out. It may have been done.
Since the solidified material filled in the first steel pipe and the second steel pipe does not come into direct contact with water, it can be held in an independent state.
In addition, the first steel pipe and the second steel pipe are pulled out in the ground area, and the first solidified material and the second solidified material are disturbed at the claws, and the first steel pipe and the second steel pipe are held on the ground without being pulled out. It may have been done.
On the ground, the solidified material filled in the first steel pipe and the second steel pipe can be held in a self-supporting state by the first steel pipe and the second steel pipe.

The steel pipe pile according to the present invention has a steel pipe and a claw portion that protrudes radially outward at an appropriate position in the longitudinal direction of the steel pipe, and is a solidified material adjacent to the claw portion when the steel pipe placed in the ground is pulled up. It is characterized by disturbing.
According to the present invention, the solidifying material can be filled in the cast steel pipe, and the solidifying materials can be integrated by disturbing the adjacent solidifying materials at the claws when the steel pipe is pulled up.

According to the method for constructing a continuous underground wall according to the present invention, the pile bodies are connected to each other by pulling out the pile bodies of the solidified material from which the first steel pipe has been pulled out while disturbing the pile bodies at the claws of the second steel pipe. It is possible to form a continuous underground wall. Therefore, it is possible to reliably construct a continuous underground wall in which piles of solidifying materials are integrated with each other with a small number of man-hours.
Moreover, it is possible to prevent the solidified material from collapsing during construction and to prevent the generation of industrial waste because bentonite or the like is not used, and it is possible to reduce the number of parts and man-hours.

Further, according to the steel pipe pile according to the present invention, since the claw portion is formed on the outer peripheral surface of the steel pipe pile, the pile body of the adjacent solidifying material can be disturbed and integrated at the time of pulling out.

It shows the steel pipe used in the construction method of the continuous underground wall by embodiment of this invention, (a) is the figure which shows the 1st steel pipe, (b) is the figure which shows the 2nd steel pipe. The second steel pipe is shown, (a) is a plan view, and (b) is a partial side view. The arrangement of the first steel pipe and the second steel pipe buried in the ground is shown, (a) is a plan view, (b) is a side view of a main part, and (c) is an explanatory view showing a claw part of the second steel pipe. be. The construction method of the continuous underground wall by 1st Embodiment is shown, (a) is the explanatory view of the process of pulling out the 1st steel pipe from the wall body in the ground, and (b) is the structural drawing. (A) and (b) are explanatory views and structural views of the process of pulling out another first steel pipe. (A) and (b) are explanatory views and structural views of the process of pulling out the second steel pipe. (A) and (b) are explanatory views and structural views of the process of pulling out another second steel pipe. (A) is an explanatory diagram of the construction process of the continuous underground wall, (b) is an explanatory diagram showing the arrangement of the first pile and the second pile, and (c) is a diagram of a modified example of the first pile. It is a figure which shows the 1st deformation example of the claw part provided in the 2nd steel pipe, (a) is a plan view, (b) is a partial cross-sectional view taken along line AA of the figure (a) which shows a claw part. It is explanatory drawing of the process of pulling out a 1st steel pipe from a wall body in the construction method of the continuous underground wall by 2nd Embodiment. It is explanatory drawing of the process of pulling out another first steel pipe. It is explanatory drawing of the process of pulling out a 2nd steel pipe. It is explanatory drawing of the process of pulling out another 2nd steel pipe. It is explanatory drawing of the process of placing the second steel pipe in the construction method of the continuous underground wall by the third embodiment. It is a figure of the process of pulling out the first steel pipe. It is a figure of the process of pulling out another first steel pipe. It is a figure of the process of pulling out the second steel pipe. It is a figure which shows the deformation example of a wall body and a claw part. It is a figure which shows the 2nd deformation example of the claw part provided in the 2nd steel pipe, (a) is a plan view, (b) is a vertical sectional view, (c) is a back view of the claw part. It is an exploded perspective view of a claw part. It shows the continuous underground wall by the modification, (a) is the explanatory view of the wall body of the 1st steel pipe and the 2nd steel pipe, and (b) is the explanatory view of the continuous underground wall. It shows a part of a continuous underground wall according to a modified example, and is an explanatory diagram of a state where a prestress unit is installed in a first steel pipe. It is a figure which shows the first pile filled with concrete. It is a figure which shows the first pile of the continuous underground wall which gave prestress. It is a figure which shows the modification of the construction method of a continuous underground wall. It is sectional drawing of the main part which shows the deformation example of a continuous underground wall.

Hereinafter, the construction method of the continuous underground wall according to the embodiment of the present invention and the second steel pipe 2 used in the construction method will be described with reference to the attached drawings.
1 to 8 are views showing a method of constructing a continuous underground wall R according to the first embodiment of the present invention.
In the first embodiment, the continuous underground wall R is constructed by using the first steel pipe 1 and the second steel pipe 2. The first steel pipe 1 is a normal steel pipe shown in FIG. 1 (a), and the second steel pipe 2 is radially outward from a position facing the outer peripheral surface at the lower portion in the longitudinal direction of the pipe body as shown in FIG. 1 (b). A pair of protruding claw portions 3 are provided. The first steel pipe 1 and the second steel pipe 2 form a steel pipe pile.

As shown in FIGS. 2A and 2B, the claw portion 3 of the second steel pipe 2 is made of, for example, steel, and has a substantially arcuate plate shape and the tip portion 3a is formed in an arcuate shape. A blade portion 4 made of a high hardness material, for example, a cemented carbide is connected to both side portions 3b of the claw portion 3 by welding or the like, and the tip portion 3a of the claw portion 3 and the blade portions 4 at both ends in the circumferential direction, for example, have a substantially cross section. It is formed in a triangular shape.
Therefore, when the second steel pipe 2 is press-fitted into the ground, the ground can be excavated by the tip portion 3a of the claw portion 3 and the blade portions 4 on both sides by linear press-fitting, rotary press-fitting, or rocking press-fitting. When the second steel pipe 2 is pulled out from the ground, the first pile made of concrete before hardening, which is adjacent to the tip portion 3a of the claw portion 3 and the blade portion 4, can be disturbed and integrated. The claw portion 3 can be installed at an appropriate position in the longitudinal direction of the second steel pipe 2 as needed.

Next, the construction method of the continuous underground wall R according to the first embodiment will be described based on each step shown in FIGS. 3 to 7.
First, for example, a press-fitting machine 6 shown in FIG. 4 is used as a press-fitting and pulling-out device, and the first steel pipe 1 and the second steel pipe 2 are alternately press-fitted and sequentially driven (steel pipe driving step). 3 (a) to 3 (c) show the wall body 7 of the first steel pipe 1 and the second steel pipe 2 continuously pressed into the ground, and the second steel pipe 2 is between the first steel pipe 1. It has been cast.
In the steel pipe placing step, the second steel pipe 2 is oscillated and press-fitted into the first steel pipe 1 previously press-fitted within a range in which the claw portion 3 does not interfere with each other, or is linearly press-fitted without oscillating.

Next, a method of constructing a continuous underground wall by pulling out the first and second steel pipes 1 and 2 from the wall body 7 will be described with reference to FIGS. 4 to 7, and FIG. ) Shows the configuration of the wall body 7 in each step.
In FIG. 4, the press-fitting machine 6 installs the lock portion of the carriage 8 on the existing first steel pipe 1 and second steel pipe 2 (or reaction force weight) to take reaction force, and each steel pipe 1 and 2 is held by the grip portion 9. It is pulled out from the ground while being gripped and filled with concrete or after filling.
It is preferable that the press-fitting machine 6 projects a plurality of first steel pipes 1 and second steel pipes 2 forming the wall body 7 from the GL surface of the ground by a height for clamping the lock portion. As a result, the press-fitting machine 6 can perform press-fitting and pulling-out operations of the first steel pipe 1 and the second steel pipe 2 while moving on the first steel pipe 1 and the second steel pipe 2.

In FIG. 4A, after the inside of each steel pipe 1 and 2 is press-fitted by the press-fitting machine 6 (or while press-fitting), earth and sand are discharged from the inside of each of the steel pipes 1 and 2 by an excavator (not shown) (excavation step). ). Next, after filling or filling the first steel pipe 1 press-fitted into the end of the wall body 7 with concrete, the press-fitting machine 6 pulls out the first steel pipe 1 already cast while taking a reaction force ( First solidification material filling process). As a result, the first pile 1A, which is made of concrete and has a substantially columnar shape, is buried in the ground. The first pile 1A is uncured but is supported by the surrounding ground.
Since the first steel pipe 1 is pulled out while filling concrete, the holes in the ground do not collapse. In FIG. 4, the GL surface of the ground is the upper surface of the first pile 1Aa (1A).

Next, the press-fitting machine 6 is moved on another first steel pipe 1 opened. While filling or filling the first steel pipe 1 adjacent to the first pile 1Aa sandwiching the second steel pipe 2, the first steel pipe 1 is pulled out by the press-fitting machine 6 (second solidifying material filling step). ). In the press-fitting machine 6, the other first steel pipe 1 is pulled out while taking a reaction force.
As shown in FIG. 5A, when the first steel pipe 1 is pulled out, the first steel pipe 1 between the second steel pipes 2 is difficult to grip, so the downing device 11 is gripped by the grip portion 9 of the press-fitting machine 6. Then, the tip portion thereof is fitted into the first steel pipe 1 and pulled out in a state of being engaged with each other. In this way, the first pile 1Ab, which is made of concrete and has a substantially columnar shape, is buried in the ground.

Next, in FIG. 6, while filling or filling the second steel pipe 2 between the first piles 1Aa and 1Ab with concrete, the press-fitting machine 6 pulls out the second steel pipe 2 while taking a reaction force. .. At that time, the first piles 1Aa and 1Ab are in an uncured state, and the second steel pipe 2 is rotated and pulled out linearly with or without swinging while being overlapped with the first piles 1Aa and 1Ab. ..
As a result, the second pile 2Aa, which is made of concrete and has a substantially columnar shape, is buried in the ground in an uncured state. Moreover, the uncured first piles 1Aa and 1Ab are disturbed by the facing claws 3 of the second steel pipe 2 and integrated with the second pile 2Aa (2A).

Here, when the first piles 1Aa and 1Ab on both sides are disturbed by the claw portion 3 of the second steel pipe 2 and integrated with the second pile 2Aa of the second steel pipe 2, the increased amount of concrete is removed through the second steel pipe 2 to be pulled out. Since it is supplied, the cross-sectional area of the second pile 2Aa at the connecting portion with the first pile 1Aa and 1Ab increases. As a result, concrete is replenished at the connecting portion between the second pile 2Aa and the first piles 1Aa and 1Ab on both sides to form a high-strength continuous underground wall R. In the example shown in FIG. 7, the second pile 2Aa is formed wide at the connecting portion with the first piles 1Aa and 1Ab on both sides.

Next, the press-fitting machine 6 is moved from the first pile 1Ab to the first steel pipe 1 in which one buried second steel pipe 2 is skipped. While or after filling the first steel pipe 1 with concrete, the first steel pipe 1 is pulled out by the press-fitting machine 6. The press-fitting machine 6 pulls out the other first steel pipe 1 while taking a reaction force, and holds the concrete first pile 1Ac in the buried state.
In this state, as shown in FIG. 7A, the second steel pipe 2 is pulled out by the press-fitting machine 6 while filling or after filling the second steel pipe 2 between the first piles 1Ab and 1Ac with concrete. .. At that time, the first piles 1Ab and 1Ac are in an uncured state, and the second steel pipe 2 is rotated so that the claw portion 3 is overlapped with the first piles 1Ab and 1Ac and is shaken or not shaken. Pull out in a straight line. As a result, the second pile 2Ab, which is made of concrete and has a substantially columnar shape, is buried in the ground in an uncured state. Moreover, since the uncured first piles 1Ab and 1Ac are disturbed by the facing claws 3 of the second steel pipe 2 and are in an uncured state with each other, the connecting portion with the second pile 2Ab is reinforced by the replenished concrete. And integrated. Moreover, as shown in FIGS. 7A and 7B, the width of the second pile 2Ab increases.

By repeating such work, the concrete first pile 1A and the second pile 2A are alternately arranged in the wall body 7. Moreover, since the first pile 1A (= 1Aa, 1Ab, 1Ac, ...) Is disturbed by the claw portion 3 of the second steel pipe 2, the first pile 1A and the second pile are as shown in FIGS. 8A and 8B. The piles 2A (= 2Aa, 2Ab, ...) Are integrated in the ground to form a continuous underground wall R in which the connecting portion of the second pile 2A with the first pile 1A has an enlarged diameter.
In addition, H steel may be constructed in the first pile 1A and the second pile 2A depending on the required wall strength of the continuous underground wall R (see FIG. 8C).

As described above, according to the method of constructing the continuous underground wall R according to the first embodiment, since the claw portion 3 facing the second steel pipe 2 press-fitted between the first steel pipes 1 is provided, the concrete is made of concrete. By sequentially repeating the process of pulling out the second steel pipe 2 filled with concrete between the first piles 1A and 1A, a continuous underground wall R in which the first pile 1A and the second pile 2A are integrated can be formed. Therefore, construction is easy and low cost.
Moreover, by replenishing concrete inside when the second steel pipe 2 is pulled out, the concrete at the joint between the first pile 1A and the second pile 2A on both sides can be reinforced to form a high-strength continuous underground wall R. , Water stoppage is also improved.

The method for constructing the continuous underground wall R according to the present invention and the second steel pipe 2 used therein are not limited to the above-described embodiment, and various changes and replacements can be made without departing from the gist thereof. These cases are also included in the technical scope of the present invention. Hereinafter, other embodiments and modifications of the present invention will be described with reference to the same or similar parts and members as those described above.

FIG. 9 shows a first modification example of the claw portion 3 installed in the second steel pipe 2.
As shown in FIG. 3A, the claw portion 13 according to the present modification may have a blade portion 14 made of, for example, a cemented carbide fixed to the tip portion 13a at predetermined intervals. As shown in FIG. 3B, the blade portion 14 is formed with an acute-angled blade 14a protruding upward. As a result, when the second steel pipe 2 is pulled out, the first piles 1A on both sides can be cut and disturbed.
Further, as another modification, a configuration in which the blade portion 14 of the claw portion 13 shown in FIG. 9 is added to the tip portion 3a of the claw portion 3 shown in FIG. 2 may be adopted. If such a configuration is adopted, the strength and cutting ability of the claw portion 3 become higher, and the disturbing effect of the uncured or semi-cured first pile 1A is improved. Further, the blade portions 4 and 14 are not limited to cemented carbide, and an appropriate high-strength alloy such as cBN can be adopted.

Next, the construction method of the continuous underground wall R according to the second embodiment of the present invention will be described with reference to FIGS. 10 to 13.
In FIG. 10, as a step of placing the first steel pipe, the first steel pipe 1 is press-fitted by the press-fitting machine 6 at intervals of one of the second steel pipes 2 along the construction direction of the wall body 7. The casting of the first steel pipe 1 may be press-fitting, rotary press-fitting, or rocking press-fitting. Next, as the first excavation step, the inside of the first steel pipe 1 is excavated by an excavator (not shown) while or after the first steel pipe 1 is driven.
Then, in the first solidifying material filling step, the first steel pipe 1 is pulled out while or after the solidifying material such as concrete is filled in the first steel pipe 1. By pulling out the first steel pipe 1, a concrete, substantially columnar first pile 1Aa is buried in the ground in an uncured state.

Further, as shown in FIG. 11, the first steel pipe 1 is pulled out while or after the solidifying material such as concrete is filled in the first steel pipe 1 at a position adjacent to the first pile 1Aa at a distance. By pulling out the first steel pipe 1, a concrete, substantially columnar first pile 1Ab is buried in the ground in an uncured state.
Next, as a second steel pipe placing process, the second steel pipe 2 is press-fitted between the first piles 1Aa and 1Ab by the press-fitting machine 6. Since the pair of claws 3 (or claws 13) are fixed to the opposite positions of the lower end of the second steel pipe 2, the second steel pipe 2 is driven by press-fitting or rocking press-fitting so as not to interfere with the first piles 1Aa and 1Ab. .. As the second excavation step, the inside of the second steel pipe 2 is excavated by an excavator (not shown) while or after the second steel pipe 2 is driven, and soil is discharged.

Next, as a second solidifying material filling step, as shown in FIG. 12, the second steel pipe 2 is pulled out by the press-fitting machine 6 while filling or after filling the second steel pipe 2 buried in the ground with concrete. As a result, the second concrete pile 2Aa is buried in the ground. When the second steel pipe 2 is pulled out, the second steel pipe 2 is pulled out while disturbing the first piles 1Aa and 1Ab on both sides by the claws 3 protruding to the outside of the second steel pipe 2. Moreover, when the second steel pipe 2 is pulled out, additional concrete is replenished through the second steel pipe 2.
At that time, the first piles 1Aa and 1Ab are in an uncured state, and the second steel pipe 2 is rotated so that the claw portion 3 is overlapped with the first piles 1Ab and 1Ac and is shaken or not shaken. Pull out in a straight line. As a result, the second pile 2Aa, which is made of concrete and has a substantially columnar shape, is buried in the ground in an uncured state. Moreover, since the uncured first piles 1Aa and 1Ab are disturbed by the facing claws 3 of the second steel pipe 2, they are integrated with the second pile 2Aa, and the connecting portion of the second pile 2Aa is expanded by the additional concrete. Be stakeout.

By repeating such work, the second pile 2A from which the second steel pipe 2 is pulled out is connected between the first piles 1A and 1A from which the first steel pipe 1 is pulled out. Moreover, since the uncured first pile 1A is disturbed by the claw portion 3 of the second steel pipe 2 and is replenished with additional concrete, as shown in FIG. 13, the first pile 1A on both sides of the second pile 2A A continuous underground wall R is formed in which the diameter of the connecting portion with the pile is expanded. The second solidifying material filling step of the second steel pipe 2 is performed at the stage where the first piles 1A and 1A placed earlier are uncured. Therefore, the number of piles 1A that can be driven up to the second solidifying material filling step is limited, and these constructions are repeated.
Also in the second embodiment, it is possible to construct a high-strength continuous underground wall R and reduce the construction man-hours and costs.

Next, the construction method of the continuous underground wall R according to the third embodiment of the present invention will be described by each step shown in FIGS. 14 to 17. In the present embodiment, a continuous underground wall R is constructed on the hard ground, and the second steel pipe 2 on which the claw portion 3 is installed is buried in the hard ground by rotary press-fitting. Therefore, the second steel pipe 2 is press-fitted first, and then the first steel pipe 1 is press-fitted.
In the second steel pipe driving step shown in FIG. 14, the second steel pipe 2 is buried in the ground by rotary press-fitting at intervals along the construction direction of the wall body 7 using the press-fitting machine 6. As the second excavation step, the inside of the second steel pipe 2 is excavated by an excavator and the soil is discharged while or after the second steel pipe 2 is driven.
Next, in FIG. 15, as the first steel pipe placing step, the first steel pipe 1 is press-fitted between the buried second steel pipe 2. As the press-fitting of the first steel pipe 1, any of press-fitting, rotary press-fitting, and rocking press-fitting may be used. The inside of the first steel pipe 1 is excavated while or after the driving of the first steel pipe 1.

Then, in the first solidifying material filling step of FIG. 15, the first steel pipe 1 is pulled out by the press-fitting machine 6 while or after the concrete is filled in the first steel pipe 1. By pulling out the first steel pipe 1, a concrete, substantially columnar first pile 1Aa is buried in the ground. Further, in FIG. 16, the first steel pipe 1 is pulled out by the press-fitting machine 6 while filling or after filling the first steel pipe 1 from which the second steel pipe 2 is skipped from the first pile 1Aa. By pulling out the first steel pipe 1, a concrete, substantially columnar first pile 1Ab is buried in the ground.
Then, in the second solidifying material filling step shown in FIG. 17, the second steel pipe 2 is press-fitted with the press-fitting machine 6 while filling or after filling the second steel pipe 2 press-fitted between the first piles 1Aa and 1Ab with concrete. Pull out. As a result, the second concrete pile 2Aa is buried in the ground.

When the second steel pipe 2 is pulled out, the second steel pipe 2 is pulled out while disturbing the first piles 1Aa and 1Ab on both sides by the claws 3 protruding to the outside of the second steel pipe 2. The second steel pipe 2 is pulled out by overlapping the claws 3 on the first piles 1Aa and 1Ab without swinging, or swinging the second steel pipe 2. As a result, the second pile 2Aa, which is made of concrete and has a substantially columnar shape, is buried in the ground in an uncured state.
Moreover, the uncured first piles 1Aa and 1Ab are disturbed by the claw portion 3 of the second steel pipe 2 and integrated with the uncured second pile 2Aa, and the connecting portion of the second pile 2Aa is formed by the supplementary concrete. The diameter is expanded.

By repeating such work, the second pile 2A from which the second steel pipe 2 is pulled out is buried between the first pile 1A and 1A from which the first steel pipe 1 is pulled out, and the first pile 1A and the second pile made of concrete are buried. The piles 2A are arranged alternately. Since the uncured first pile 1A is disturbed by the claw portion 3 of the second steel pipe 2, it is integrated in the ground, and supplementary concrete is added to the first pile 2A on both sides as shown in FIG. A continuous underground wall R is formed in which the diameter of the connecting portion with the pile 1A is expanded.
Also in the third embodiment, a high-strength continuous underground wall R can be constructed, and the construction man-hours and costs can be reduced.

In addition, when constructing the continuous underground wall R, other existing structures may be installed in the vicinity. In this case, it is an outer tangent line of one of the wall body 7 composed of the first steel pipe 1 and the second steel pipe 2 (first pile 1A and second pile 2A) arranged in the construction direction as shown in FIG. It is necessary to construct so that the claw portion 3 of the second steel pipe 2 does not protrude from the tangent line L. In this case, the claw portion 3 does not protrude from the circumscribed line L by press-fitting the second steel pipe 2 or swinging and press-fitting within the gap between the circumscribed line L and the adjacent first steel pipe 1. It can be constructed as follows. In this case, the claw portion 3 may be formed, for example, in the shape of a substantially triangular plate having a convex curve on each side.
Further, the existing structure may be constructed not only on one side of the wall body 7 but also on the other side facing the wall body 7. By press-fitting the second steel pipe 2 in the region sandwiched between both circumscribed lines L and La, or by rocking and press-fitting within the gap between the circumscribed lines L and La on both sides and the adjacent first steel pipe 1. , The claw portion 3 can be constructed so as not to protrude from the circumscribed lines L and La.

In each of the above-described embodiments and modifications, the claw portion 3 is fixedly arranged to face the second steel pipe 2, but in this case, the claw portion 3 becomes a resistance when the second steel pipe 2 is press-fitted into the ground. Therefore, it may be performed by rotary press-fitting or rocking press-fitting.
On the other hand, in this second modification, the claw portion 16 is installed so that it can be expanded / contracted or moved forward / backward. Hereinafter, an example of the expandable claw portion 16 will be described with reference to FIGS. 19 and 20. At the lower end of the second steel pipe 2 shown in FIG. 19, the expandable and contractible claws 16 according to the second modification are installed facing each other at opposite positions. The claw portion 16 fits the bearing portion 17 fixed to the outer peripheral surface of the second steel pipe 2, the support shaft 18 inserted through the through hole of the bearing portion 17, and both ends of the support shaft 18. A claw portion main body 19 that can rotate in the vertical direction around the 18 is provided.

As shown in FIG. 20, the claw portion main body 19 has a plate shape having a concave curved surface along the outer peripheral surface of the second steel pipe 2, and a recess 19a into which the bearing portion 17 can be fitted is formed at the base thereof, and the blade portion is formed. The tip portion 19b of the eggplant is a convex curved surface or an inclined surface that is inclined in the thickness direction. Holes for fitting the support shaft 18 are formed on both side surfaces in the recess 19a. Further, both end portions of the recess 19a are stopper portions 19c, and when the claw portion main body 19 is opened in a horizontal position, it comes into contact with the outer peripheral surface of the second steel pipe 2 and can receive a disturbing load at the time of pulling out.

The claw portion main body 19 is normally held in an upright position where the concave curved surface is in contact with the outer peripheral surface of the second steel pipe 2, and in this state, the tip portion 19b is moved upward as it is separated from the outer peripheral surface of the second steel pipe 2 in the thickness direction. Form a curved or sloping pocket P. When the second steel pipe 2 buried in the ground is pulled out, the concrete or the like of the first pile 1A flows into the pocket P of the tip portion 19b, so that the claw portion main body 19 opens outward around the support shaft 18 and expands to a substantially horizontal position. The diameter is increased and the first pile 1A can be excavated and disturbed.
On the other hand, when the second steel pipe 2 is press-fitted, the claw portion main body 19 stands up and is held in a reduced diameter state in contact with the outer peripheral surface, and does not interfere with the press-fitting. Therefore, the second steel pipe 2 can be press-fitted linearly as well as rotary press-fitting and rocking press-fitting.

Further, in each of the above-described embodiments, the claw portions 3, 13 and 16 are installed near the lower end portion of the second steel pipe 2 to provide a continuous underground wall R capable of stopping water over almost the entire length and having wall strength. I tried to construct it. However, for example, if the continuous underground wall R is intended for water stoppage rather than wall strength, the claw portion 3 or the claw portion 16 may be installed in the water stop range. A method of constructing the continuous underground wall R according to such a modification will be described with reference to FIG.
In FIG. 21A, for example, when there is a clay layer in the ground and groundwater is flowing above the clay layer, a continuous wall body R1 may be constructed on the upper side of the clay layer in order to stop the groundwater. .. Therefore, the claw portion 3 is installed at an intermediate position in the longitudinal direction of the second steel pipe 2 corresponding to the clay layer.

In this modification, for example, the first steel pipe 1 is pulled out while filling or after filling the first steel pipe 1 that has been cast, and the first piles 1Aa and 1Ab are sequentially constructed. Next, by pulling out the second steel pipe 2 while filling or after filling the second steel pipe 2 between the first piles 1Aa and 1Ab, the first pile 1Aa is on the upper side from the portion where the claw portion 3 is provided. , 1Ab of concrete is disturbed, and supplementary concrete is added to widen both sides of the second pile 2Aa and integrated with the first piles 1Aa and 1Ab. By sequentially performing such operations, the continuous wall body R1 shown in FIG. 21B is formed in the water stop range.
In this case, even if the first pile 1A and the second pile 2A on the lower side of the continuous wall body R1 are not connected to each other, the earth pressure can be supported by the bending strength of the first pile 1A and the second pile 2A themselves and is continuous. The wall strength of the underground wall R can be secured. Moreover, it is not necessary to disturb the lower side of the claw portion 3 by excavating the first pile 1A, the construction is quicker, and the cost of materials such as concrete can be reduced.

Further, prestress may be introduced into the first pile 1A and the second pile 2A of the continuous underground wall R by a post-tension method. This modification will be described with reference to FIGS. 22 to 24, but in the figure, only the first steel pipe 1 and the corresponding first pile 1A are shown, and the first pile corresponding to the other first steel pipe 1 and the second steel pipe 2 is shown. 1A and the second pile 2A are omitted.
Similar to each of the above-described embodiments, the first steel pipe 1 and the second steel pipe 2 are driven into the ground, and the inside of the first steel pipe 1 and the second steel pipe 2 is excavated to remove soil. The prestress unit 21 is installed in the first steel pipe 1 shown in FIG. 22. In the prestress unit 21, a sheath tube 24 having a built-in PC steel wire 23 is installed on one surface of the end plate 22, and the PC steel wire 23 is passed through the other surface of the end plate 22 and fixed by the fixing tool 25. .. The prestress unit 21 is installed at the lower end of the first steel pipe 1 from which the end plate 22 is discharged, and the PC steel wire 23 and the sheath pipe 24 are extended from the upper opening to the outside through the inside of the first steel pipe 1.

Then, by the same process as each of the above-described embodiments, the first steel pipe 1 is pulled out from the ground by the press-fitting machine 6 while or after the concrete is filled in the first steel pipe 1 as shown in FIG. Generate one pile 1A. When the second steel pipe 2 is pulled out while filling or after filling the concrete, the first pile 1A provided on both sides of the second steel pipe 2 is disturbed by the claw portion 3 and integrated with the second pile 2A. Next, after the first pile 1A is cured to develop a predetermined strength, a lid 26 is installed on the upper surface of the concrete first pile 1A, and the PC steel wire 23 in the sheath pipe 24 is pulled through and fixed. The tool 25 tensions and holds the first pile 1A. Prestress (compressive force) is applied to the second pile 2A corresponding to the second steel pipe 2 by the same process.
As a result, prestress is applied to the continuous underground wall R of the first pile 1A and the second pile 2A corresponding to all the first steel pipe 1 and the second steel pipe 2, and the tensile stress is applied even if a load is applied. It can be controlled to prevent cracks and the like.

It is not necessary to apply prestress to the first pile 1A and the second pile 2A corresponding to all the first steel pipe 1 and the second steel pipe 2. For example, prestress may be applied only to the first pile 1A or only the second pile 2A. Alternatively, prestress may be introduced only in a part of the first pile 1A and the second pile 2A, or only in the concrete of the part where the bending load is applied.

In the construction method of the continuous underground wall R according to each of the above-described embodiments and deformation examples, when the first pile 1A made of concrete is excavated and disturbed by the claws 3, 13 and 16 when the second steel pipe 2 is pulled out, the first It is assumed that one pile 1A is in an uncured state. It is preferable that the first pile 1A is disturbed by the claw portions 3, 13 and 16 within the range from the condensation start time to the condensation end time of the concrete. Further, even after the condensation completion time, the first pile 1A may be scraped and disturbed in a semi-cured state or a cured state. Even in this case, it can be integrated with the second pile 2A with additional supplementary concrete.

Further, in the method of constructing the continuous underground wall R such as each of the above-described embodiments and modifications, the press-fitting machine 6 is used to press-fit and pull out the first steel pipe 1 and the second steel pipe 2. It is not limited to such a configuration. Instead of the press-fitting machine 6, a known press-fitting / pulling-out device can be adopted.

Further, although the claw portions 3, 13 and 16 of the second steel pipe 2 are formed in the shape of an arc plate, they may be formed in the shape of a ring all around the second steel pipe 2. If this configuration is adopted, it is not necessary to align the claw portion 3 so as to overlap with the first pile 1A when the second steel pipe 2 is pulled out, and it is not necessary to swing or rotate the claw portion 3.
In this case, it is preferable to drive the second steel pipe 2 before the first steel pipe 1 as in the third embodiment. Further, in the construction method of the continuous underground wall R such as each of the above-described embodiments and deformation examples, a part of the first steel pipe 1 is set longer than the other first steel pipe 1 and the second steel pipe 2, and the first pile 1A is set. Or the second pile 2A may be formed.

Next, a modified example of the construction method of the continuous underground wall R according to the second embodiment described above will be described with reference to FIG. 25.
In the construction method of this modification, in FIG. 25, the inside of the first steel pipe is excavated with an excavator while or after the first steel pipe 1 is driven at intervals, but the second steel pipe 2 is the first steel pipe 1. It is not placed in sequence between. For example, the second steel pipe 2 is placed between two adjacent first steel pipes 1 as appropriate. The inside of the second steel pipe 2 is excavated while or after the second steel pipe 2 is driven.
Then, the first steel pipe 1 is sequentially pulled out while or after the solidifying material is filled in the first steel pipe 1 on both sides. The second steel pipe 2 is pulled out while or after the solidifying material is filled in the second steel pipe 2 placed between the obtained first piles 1Aa and 1Ab. At that time, the uncured first pile 1Aa and the first pile 1Ab are pulled out while being disturbed by the claw portion 3 of the second steel pipe 2.
Next, as shown in FIG. 25, the second steel pipe 2 may be placed between the first pile 1Ab and the first steel pipe 1 and constructed in the same manner. Alternatively, the second steel pipe 2 may be placed between the adjacent first steel pipes 1 at a distant position and constructed in the same manner. In this way, it is not always necessary to sequentially drive the second steel pipe 2 between the first steel pipes 1 that have been driven, and as a result, a continuous wall R that is continuous between the first pile 1A and the second pile 2A is constructed. I hope I can.

FIG. 26 shows a continuous underground wall R according to another modification.
When a continuous underground wall R is constructed in a river, swamp H, etc., the solidified material such as concrete cannot stand on its own before hardening in water. Therefore, the first steel pipe 1 of the first pile 1A and the second steel pipe 2 of the second pile 2A constituting the continuous underground wall R are not completely pulled out, but are submerged in the water above the first pile 1A and the second pile 2A. You may leave a part and cover it.
In the continuous underground wall R according to this modification, the first steel pipe 1 and the second steel pipe 2 are pulled out halfway to form the first pile 1Aa, 1Ab and the second pile 2Aa in the ground of the bottom of the water such as a river or a swamp H. The claw portion 3 of the second steel pipe 2 is disturbed and integrated. The continuous underground wall R in this portion is in contact with the ground.
In water such as rivers and swamps from above, the first steel pipe 1 is left above the first piles 1Aa and 1Ab and is in contact with water. Moreover, the area above the water surface of the first steel pipe 1 is cut as necessary. The second steel pipe 2 is also left above the second pile 2Aa in the ground, and is in contact with water in water such as rivers and swamps. Moreover, the claw portion 3 at the lower end of the second steel pipe 2 is buried in the ground. The area above the water surface of the second steel pipe 2 is cut as necessary. A joint 28 may be provided at the upper ends of the first steel pipe 1 and the second steel pipe 2 to connect and extend the steel pipe, or the joint 28 may separate and remove the pipe.
The rooting portion P from the bottom of the water to the upper part of the first pile 1Aa, 1Ab and the second pile 2Aa in the ground increases the strength of the continuous underground wall R by leaving the first steel pipe 1 and the second steel pipe 2.

Further, in the configuration in which the first steel pipe 1 and the second steel pipe 2 are left in a part of the upper portion of the first pile 1A and the second pile 2A in the longitudinal direction, the wall portion protrudes above the ground such as the high top end as well as underwater. It can also be applied when forming a continuous wall in such a region. As a result, the first pile 1A and the second pile 2A of the solidifying material are protected by the first steel pipe 1 and the second steel pipe 2 and brought into contact with the continuous wall surface where earth pressure is applied, for example, on the wall above the ground, and the continuous wall is formed. Can be linked to a part of. The first steel pipe 1 and the second steel pipe 2 on the ground following the first pile 1A and the second pile 2A stand up with a slight gap. In the present specification, such a continuous wall extending above the ground is also included in the continuous underground wall R.
Further, as another modification of the continuous underground wall R according to the present embodiment, there is a soil wall on one side of the arrangement of the first steel pipe 1 and the second steel pipe 2 left above the first pile 1A and the second pile 2A. Or the solidifying material may be in contact and the other side may be in contact with the space. Alternatively, when the space is in contact with both sides of the first steel pipe 1 and the second steel pipe 2, or when the earthen wall or the solidifying material is in contact with one side of the first steel pipe 1 and the second steel pipe 2, the other side is in contact with the earthen wall or the solidifying material. Various cases such as when the water surface is in contact can also be included.

1 1st steel pipe 1A, 1Aa, 1Ab, 1Ac 1st pile 2 2nd steel pipe 2A, 2Aa, 2Ab 2nd pile 3, 16 Claws 6 Press-fitting machine 21 Prestress unit 23 PC steel wire 24 Sheath pipe R Continuous underground wall

Claims (16)

A steel pipe placing process in which the first steel pipe and the second steel pipe are continuously and alternately placed along the construction direction,
An excavation step of excavating the inside of the first steel pipe and the second steel pipe while or after driving the first steel pipe and the second steel pipe.
The first solidifying material filling step of pulling out the first steel pipe while filling or filling the first steel pipe arranged every other pipe with the solidifying material.
Solidification filled in the first solidifying material filling step by a claw portion protruding to the outside of the second steel pipe while filling or filling the second steel pipe arranged between the first steel pipes. The second solidifying material filling process of pulling out the second steel pipe while disturbing the material,
A method of constructing a continuous underground wall, which is characterized by being provided with. The first steel pipe placing process in which the first steel pipe is placed at intervals along the construction direction,
The first excavation step of excavating the inside of the first steel pipe while or after driving the first steel pipe.
The first solidifying material filling step of pulling out the first steel pipe while filling or after filling the first steel pipe with the solidifying material.
The second steel pipe driving process in which the second steel pipe is placed between the first steel pipes,
A second excavation step of excavating the inside of the second steel pipe while or after driving the second steel pipe.
The second steel pipe is pulled out while filling the solidifying material in the second steel pipe or after filling the second steel pipe while disturbing the solidifying material filled in the first solidifying material filling step by the claws protruding to the outside of the second steel pipe. The second solidifying material filling process and
A method of constructing a continuous underground wall, which is characterized by being provided with. The second steel pipe placing process, in which the second steel pipe is placed at intervals along the construction direction,
A second excavation step of excavating the inside of the second steel pipe while or after driving the second steel pipe.
The first steel pipe driving process in which the first steel pipe is placed between the second steel pipes,
The first excavation step of excavating the inside of the first steel pipe while or after driving the first steel pipe.
The first solidifying material filling step of pulling out the first steel pipe while filling or after filling the first steel pipe with the solidifying material.
The second steel pipe is pulled out while filling the solidifying material in the second steel pipe or after filling the second steel pipe while disturbing the solidifying material filled in the first solidifying material filling step by the claws protruding to the outside of the second steel pipe. The second solidifying material filling process and
A method of constructing a continuous underground wall, which is characterized by being provided with. The method for constructing a continuous underground wall according to claim 1 or 2, wherein the claw portion is provided at a position where the claw portion does not interfere with the first steel pipe when the second steel pipe is placed. The claw portion of the second steel pipe is provided in a gap between one circumscribed line of the first steel pipe and / or the second steel pipe or two opposing circumscribed lines on both sides and the adjacent first steel pipe. The method for constructing a continuous underground wall according to any one of 4 to 4. The method for constructing a continuous underground wall according to any one of claims 1 to 5, wherein the second steel pipe provided with the claw portion is driven by press-fitting, rotary press-fitting, or rocking press-fitting. The continuous according to any one of claims 1 to 6, wherein when the second steel pipe is pulled out, the solidified material filled in the first solidifying material filling step is in a state from the condensation start time to the condensation end time. Construction method of underground wall. The method for constructing a continuous underground wall according to any one of claims 1 to 7, wherein the second steel pipe has a claw portion that can be expanded and contracted outward. The invention according to any one of claims 1 to 8, wherein when the second steel pipe is pulled out, a new solidifying material is replenished while disturbing the solidifying material filled in the first solidifying material filling step by the claw portion. Construction method of the continuous underground wall. According to any one of claims 1 to 9, a press-fitting machine is installed in the first steel pipe and / or the second steel pipe, and the first steel pipe and the second steel pipe are driven and pulled out by the press-fitting machine. The described method of constructing a continuous underground wall. A PC steel wire is installed in the excavated first steel pipe and / or second steel pipe.
Claims 1 to 10 in which the PC steel wire is tensioned to introduce prestress after fixing the first solidifying material corresponding to the first steel pipe and / or the second solidifying material corresponding to the second steel pipe. The method for constructing a continuous underground wall according to any one of the items. The first steel pipe and the second steel pipe are pulled out in the area of the ground, and the first solidifying material and the second solidifying material are disturbed at the claw portion, and the first steel pipe and the second steel pipe are not pulled out in water. The method for constructing a continuous underground wall according to any one of claims 1 to 11. The first steel pipe and the second steel pipe are pulled out in the area of the ground, and the first solidifying material and the second solidifying material are disturbed at the claw portion, and the first steel pipe and the second steel pipe are not pulled out on the ground. The method for constructing a continuous underground wall according to any one of claims 1 to 11. With steel pipe,
It has a claw portion protruding outward in the radial direction at an appropriate position in the longitudinal direction of the steel pipe.
When the steel pipe placed in the ground is pulled up, the claw portion is pulled up together with the steel pipe, and the first pile made of a solidifying material adjacent to the steel pipe is disturbed by the claw portion, thereby passing through the steel pipe to the ground. A steel pipe pile characterized by being integrated with a second pile made of solidified material buried in the pile to form a continuous underground wall. It has a pair of the claws and
The steel pipe pile according to claim 14, wherein the pair of claws protrudes radially outward from a position facing the outer peripheral surface of the steel pipe. The steel pipe pile according to claim 14, wherein the claw portion can be expanded and contracted outward.

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