JP2011058189A - Liner plate and deep foundation construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liner plate and a deep foundation construction method, which achieves safe work and improves work efficiency. <P>SOLUTION: In this liner plate, four supporting parts 53 are inserted into recessed parts 12a of a connection ring 12, respectively, and the upper face of a flange 53a on the upper side is abutted on the rear surface of a flange 12b on the upper side of the connection ring 12 to fix on a frame piece 52. Thus, a liner plate unit 11 is supported by four supporting parts 53 through the connection ring 12. The liner plate units 11, 11 are mutually connected through the connection rings 12, 12 outside a vertical shaft 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liner plate and a deep foundation method.

  In recent years, liner plates are sometimes used in deep foundation methods. The liner plate is provided so as to cover the inner wall surface of the shaft and is used as a soil retaining material.

  The deep foundation method using the liner plate has a process in which an operator connects the flange portions of a plurality of liner plates with bolts in the shaft to be provided on the inner wall surface of the shaft as shown in Patent Document 1, for example. It was.

  In this deep foundation method, a backfill material is injected between the outer peripheral surface of the liner plate and the inner wall surface of the shaft, and concrete is placed in the shaft, and the liner plate is fixed as it is in the shaft. It was.

Japanese Patent No. 3084141

  However, in the conventional liner plate and the deep foundation method described above, the worker has to perform the connecting operation of the liner plate in the shaft, which is dangerous and the work efficiency is also poor.

  Further, in the conventional liner plate and the deep foundation method described above, the liner plate is buried in the shaft by placing concrete, so that the cost becomes high, and the outer peripheral surface of the liner plate and the inner wall surface of the shaft There was a problem that the concrete could not be sufficiently filled between the two and a shaft with sufficient strength could not be obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liner plate and a deep foundation method capable of safely working and improving work efficiency.
Another object of the present invention is to provide a liner plate and a deep foundation method capable of reducing cost and obtaining a high-strength shaft.

In order to achieve the above object, the liner plate of the present invention comprises:
A plurality of cylindrical liner plate units that are connected to the inner wall surface of the shaft to be excavated and can be pulled out from the shaft,
A liner plate provided with a connecting ring for connecting the liner plate units to each other, wherein the liner plate unit is fixed to an upper end of the liner plate unit, and a recess opening outward is formed.
The liner plate unit includes a plurality of projecting support portions provided around the excavation position of the shaft and on a base installed on the ground, and are inserted into the recesses of the connection ring. It can be supported via a ring.

  Further, the liner plate units can be connected to each other via the connecting ring and can be released outside the shaft.

  Moreover, it can support by the said support part so that it can move to an up-down direction in the excavation position of the said shaft.

  Further, it is possible to pull out a predetermined distance from the shaft depending on a predetermined height of the concrete placed in the shaft.

Further, the base is formed as a frame by upper and lower joining plates in which through holes are formed, and frame pieces joined by the joining plates,
A plurality of rod-shaped fixing members may be fitted into the through holes of the joining plate and driven into the ground.

  The liner plate unit may be fixed with a connecting ring for connecting the liner plate units to the lower end.

  Further, the support portion may be formed of H-shaped steel, and the connection ring may be supported by an upper flange portion.

  The connecting ring fixed to the upper end of the liner plate unit may have a U-shaped cross section.

  In addition, the support portion may be slidably provided on the base.

The liner plate unit has a corrugated shape having a concave portion,
The liner plate unit may be supported by inserting the support portion into the concave portion.

In order to achieve the above object, the deep foundation method of the present invention is:
A step of excavating the shaft, a step of connecting a plurality of cylindrical liner plate units each having a connecting ring formed with an outwardly-opened concave portion fixed to the upper end through the connecting ring, A deep foundation method having a step of installing the connected liner plate unit on an inner wall surface,
A plurality of projecting support portions provided around the excavation position of the shaft and on a base installed on the ground are fixed to the upper end of the liner plate unit disposed at the excavation position of the shaft. Inserting into the recess of the connecting ring and supporting the liner plate unit via the connecting ring;
A step of connecting the liner plate unit supported by the support portion and the other liner plate unit via the connection ring outside the shaft.

A step of pulling out the liner plate unit from the shaft,
Removing the connection between the liner plate units by the connection ring outside the shaft.

  The liner plate unit is supported so as to be movable in the vertical direction at the excavation position of the shaft.

  Moreover, it has the process of pulling out the said liner plate unit from the said shaft within a predetermined distance according to the predetermined height of the concrete cast | placed in the shaft.

According to the present invention, it is possible to provide a liner plate and a deep foundation method capable of safely working and improving work efficiency.
Moreover, according to this invention, while reducing cost, the liner plate and deep foundation method which can obtain a high intensity | strength shaft can be provided.

It is a perspective view showing the structure of the liner plate and support frame which concern on embodiment of this invention. It is a perspective view showing the state before the connection of the liner plate unit shown in FIG. 1, and the structure of a support frame. FIG. 3 is an enlarged perspective view of the vicinity of a connection portion between a connection ring fixed to the liner plate unit shown in FIG. 2 and a support portion fixed to a support frame. FIG. 2 is an enlarged cross-sectional view of the vicinity of a connecting portion of the liner plate unit shown in FIG. It is sectional drawing for demonstrating the deep foundation construction method which concerns on embodiment of this invention. It is a partially-omission perspective view showing the structure of the support frame provided with the fixing member which concerns on the modification of this invention.

  A liner plate and a deep foundation method according to an embodiment of the present invention will be described below with reference to the drawings.

The liner plate 1 can be installed on the inner wall surface of the shaft 2 so that it can be pulled out, and is used as a soil retaining material.
As illustrated in FIG. 1, the liner plate 1 includes a plurality of liner plate units 11 and a plurality of connecting rings 12 that connect the liner plate units 11 to each other. The liner plate 1 is configured by sequentially connecting a plurality of liner plate units 11 from above through a connecting ring 12 at an excavation position of the shaft 2. Although FIG. 1 shows a state where two liner plate units 11 are connected, a predetermined number of liner plate units 11 are further connected via a connecting ring 12 according to the depth of the shaft 2. The liner plate 1 is configured.

As shown in FIGS. 1 and 2, the liner plate unit 11 is formed of a cylindrical steel plate and has a corrugated shape in the vertical direction. The corrugated shape of the liner plate unit 11 has a concave portion 11a.
As shown in FIG. 4, a plurality of bolt holes 11 b for fixing the connecting ring 12 are formed in the peripheral portions of the upper and lower ends of the liner plate unit 11, and are connected to the peripheral portions of the upper and lower ends of the liner plate unit 11. The ring 12 can be attached. 1 and 2, the connecting ring 12 is not fixed to the peripheral edge at the lower end of the liner plate unit 11 located at the lowermost part because it is not necessary to connect another liner plate unit.

The connecting ring 12 connects the liner plate units 11 and supports the liner plate unit 11 together with a support portion 53 described later. The connection ring 12 is formed of, for example, a steel material.
As shown in FIG. 4, the connection ring 12 is configured by a ring having a U-shaped cross section, and includes a recess 12 a that opens outward along the circumference, and upper and lower flange portions 12 b. A support portion 53 is inserted into the recess 12 a and the connection ring 12 is supported by the support portion 53, whereby the liner plate 11 and thus the liner plate 1 are supported through the connection ring 12.

The connection ring 12 is formed with a plurality of bolt holes 12c for fixing to the other connection ring 12 in one of the upper and lower flange portions 12b, and for fixing to each liner plate unit 11 to the other of the upper and lower flange portions 12b. A plurality of bolt holes 12d are formed.
The connecting ring 12 is inserted into the bolt hole 11b and the bolt hole 12d, and the nut 7 is screwed into the bolt 6 so that one of the upper and lower peripheral edges or the upper and lower peripheral edges of each liner plate unit 11 is engaged. Fixed to. The connecting rings 12 are connected to each other by inserting bolts 6 into the bolt holes 12 c and 12 c and screwing nuts 7 into the bolts 6.

  As shown in FIGS. 1 to 4, the support frame 5 is a support member that guides the liner plate 1 to the shaft 2 and supports the liner plate 1 together with the connecting ring 12. The support frame 5 includes a base 51 installed on the ground formed by joining steel materials and a support portion 53 that is a projecting support piece provided near the center of each frame piece 52 of the base 51. It has. The base 51 is installed around the excavation position of the shaft 2. 1 and 2, only two support portions 53 among the four support portions 53 are illustrated.

The support portion 53 is formed of H-shaped steel and has upper and lower flange portions 53a and 53b and a web portion 53c.
As shown in FIGS. 3 and 4, the upper flange portion 53 a is inserted into the recess 12 a of the connection ring 12, and the upper surface (support surface) is in contact with the back side of the upper flange portion 12 b of the connection ring 12, The connection ring 12 is supported.
As shown in FIG. 4, the lower flange portion 53b is formed shorter in the longitudinal direction than the upper flange portion 53a. For this reason, only a part of the upper flange portion 53 a and the web portion 53 c are inserted into the recess 12 a of the connection ring 12, and the support portion 53 is easily inserted into the recess 12 a of the connection ring 12.
The lower flange portion 53b is formed with a plurality of guide holes 531b whose longitudinal direction is the liner plate 1 installed in the frame of the base 51.

As shown in FIG. 4, the frame piece 52 has a plurality of bolt holes 52 a for fixing the support portion 53. The support portion 53 is fixed to the frame piece 52 by inserting the bolt 8 into the guide hole 531 b and the bolt hole 52 a of the support portion 53 and screwing the nut 9 into the bolt 8. A washer may be used when the nut 9 is screwed onto the bolt 8.
The fixing position of the support portion 53 with respect to the connecting ring 12 can be adjusted by the guide hole 531b of the support portion 53.

Next, the deep foundation method using the liner plate 1 according to the embodiment of the present invention will be described with reference to FIG.
First, the support frame 5 is installed so that the position where the shaft 2 is excavated is located in the frame. After the support frame 5 is installed, the shaft 2 is excavated by, for example, a clam shell 60 as shown in FIG. After mechanical excavation by the clamshell 60, an operator uses the handrail 70 or the like to correct and excavate the natural ground.

Next, as shown in FIG. 5 (B), the liner plate unit 11 with the connecting ring 12 fixed to the upper end is suspended by, for example, a crane 80, placed at the excavation position of the shaft 2, and set at a predetermined height. . As shown in FIG. 2, the connection ring 12 is installed at a position higher than the ground and can be supported by the support portion 53.
As shown in FIGS. 2 and 3, the four support portions 53 are respectively inserted into the recesses 12 a of the connection ring 12, and the upper surface (support surface) of the upper flange portion 53 a is connected to the upper flange portion 12 b of the connection ring 12. It is made to contact with the back surface of. The bolt 8 is inserted into the guide hole 531 b of the support portion 53 and the bolt hole 52 a of the frame piece 52, and the nut 9 is screwed into the bolt 8 to fix the support portion 53 to the frame piece 52. Accordingly, the liner plate unit 11 is supported by the four support portions 53 via the connection ring 12. And the lifting tool of the crane 80 is removed from the liner plate unit 11 to which the connecting ring 12 is fixed.

  Next, the shaft 2 is excavated to a predetermined depth by the clam shell 60 as shown in FIG. Then, corrective excavation by workers is performed.

  Next, as shown in FIG. 5D, another liner plate unit 11 having the connection ring 12 fixed to the upper and lower ends is suspended by a crane 80, and the connection ring 12 fixed to the lower end is attached to the support frame 5. It overlaps on the connecting ring 12 fixed to the upper end of the supported liner plate unit 11. At this time, the connecting rings 12 are brought into contact with each other so that the positions of the bolt holes 12c of the connecting rings 12 coincide with each other.

  1 and 4, the bolt 6 is inserted into the bolt holes 12c and 12c, and the nut 7 is screwed into the bolt 6 and tightened, whereby the liner plate units 11 and 11 are connected to each other. , 12 for connection. This operation can be performed on the ground outside the shaft 2. The connection between the liner plate units 11 and 11 is strengthened by the connection by the two connection rings 12 and 12. Note that this connection operation can be performed while the suspension of the liner plate unit 11 by the crane 80 is held or in a state in which the suspension is released.

Next, in a state where the connected liner plate units 11 and 11 are suspended by the crane 80, the support of the lower liner plate unit 11 by the four support portions 53 is released. Specifically, the support portion 53 is removed from the frame piece 52 by releasing the screwing of the nut 9 to the bolt 8.
Thereafter, the liner plate units 11 and 11 connected while being suspended by the crane 80 are lowered into the shaft 2 by a predetermined distance, and the connection ring 12 fixed to the upper end of the upper liner plate unit 11 is supported by the four support portions 53. Then, the lifting tool of the crane 80 is removed from the liner plate unit 11.

  Next, as shown in FIG. 5 (E), the shaft 2 is excavated to a predetermined depth by the clam shell 60. Then, corrective excavation by workers is performed.

Thereafter, a new liner plate unit 11 is connected from above, release of the support of the liner plate 1 (the connected liner plate unit 11) by the support 53, and a predetermined distance of the liner plate 1 into the shaft 2 is reached. As shown in FIG. 5 (F), the descent, the support of the liner plate 1 through the connecting ring 12 by the support portion 53, the mechanical excavation by the clamshell 60, the correction excavation by the worker, etc. are repeated several times, as shown in FIG. Drill the shaft 2 to the length.
In the state where the excavation of the shaft 2 has been completed, the liner plate 1 is supported by the support portion 53 via the connecting ring 12 fixed to the upper end of the liner plate unit 11 positioned at the uppermost position.

  After excavation of the shaft 2, as shown in FIG. 5 (G), the main bars 90 and the hoop bars 91 are arranged in the shaft 2 to assemble the reinforcing bars.

Then, using the concrete chute 100, the concrete 110 is placed in the shaft 2, and the liner plate 1 composed of a plurality of liner plate units 11 is gradually pulled out from the shaft 2.
Specifically, when the concrete 90 is cast and rises to a predetermined height or more from the foundation bottom, the liner plate 1 is used for the shaft 2 by using the crane 80 according to the predetermined height of the cast concrete 110. When a connecting portion by the connecting ring 12 of the liner plate unit 11 appears outside the shaft 2 while being pulled out from the inside by a predetermined distance, the liner plate units 11 are connected to each other as shown in FIG. Remove and release.
To disconnect the liner plate units 11 from each other, the four support portions 53 support the connection ring 12 of the liner plate unit 11 located second from the top, while releasing the screwing of the bolt 6 and the nut 7. Then, the connection rings 12 are disconnected, and the liner plate unit 11 located at the top is lifted by the crane 80.
Thus, the liner plate 1 is pulled out from the shaft 2 while disconnecting the liner plate unit 11 from above according to the height of the concrete 110 in the shaft 2.
Note that the concrete chute 100 is manually removed one by one.
The placing work of the concrete 110 is performed while stabilizing the liner plate 1 while supporting the connecting ring 12 by the support portion 53 as necessary.

  As shown in FIG. 5 (I), the concrete foundation 110 is driven into the shaft 2 and the liner plate 1 is pulled out from the shaft 2, and the deep foundation method is completed.

  As described above, in the present embodiment, the liner plate unit 11 can be connected to the outside of the shaft 2 on the ground or the like while being supported by the support portion 53. The work can be performed safely without being accompanied, and the work efficiency of the connecting work is improved.

  Moreover, in this Embodiment, since the liner plate 1 was supported by the support part 53, the liner plate 1 can be supported so that it can move to the up-down direction in the excavation position of the shaft 2. For this reason, the liner plate 1 can be stably guided and installed to the shaft 2, and the liner plate 1 can be stably pulled out from the shaft 2. Moreover, the efficiency of the connection operation | work of the liner plate 1 and a connection release operation | work can be improved.

  Moreover, in this Embodiment, since the liner plate 1 was pulled out from the shaft 2 with the concrete 110 placement operation, the liner plate 1 would not be buried in the shaft 2, The cost for the foundation method can be reduced. Furthermore, the concrete 110 can be sufficiently filled in the shaft 2, and a shaft with sufficient strength can be obtained.

  Further, in the present embodiment, when the liner plate 1 is pulled out from the shaft 2, the liner plate units 11 are easily disconnected from each other outside the shaft 2 such as on the ground. Is good.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. The liner plate units 11 constituting the liner plate 1 may have the same or different lengths in the height direction.

In the present embodiment, the example in which the liner plate units 11 are connected to each other via the two connecting rings 12 fixed to each other as shown in FIG. 4 has been described. You may make it connect using only the ring 12. FIG.
That is, using only the connecting ring 12 fixed to the peripheral edge of the upper end of the liner plate unit 11 positioned on the lower side, the peripheral edge of the lower end of the liner plate unit 11 positioned on the upper side is directly bolted to the connecting ring 12. 6. You may make it connect using the nut 7. FIG.
In this case, the bolt hole 12c of the connecting ring 12 fixed to the peripheral edge of the upper end of the liner plate unit 11 positioned on the lower side and the bolt hole 11b of the peripheral edge of the lower end of the liner plate unit 11 positioned on the upper side, By inserting the bolts 6 and screwing the nuts 7, the liner plate units 11 are connected to each other via one connecting ring 12.
As described above, the connection ring 12 is not necessarily fixed to the peripheral edge portions of the upper and lower ends of each liner plate unit 11, and the connection ring 12 may be fixed only to the peripheral edge portion of the upper end of the liner plate unit 11.
Further, it is not necessary to fix the connection ring 12 to all the liner plates 11, and some of the liner plates 11 may be directly connected without using the connection ring 12.

  Further, in the present embodiment, the example in which the connection ring 12 is configured by a ring having a U-shaped cross section and the recess 12a that opens outward along the entire circumference has been described, but the support portion 53 is inserted. A connection ring in which a recess 12a is formed only in the portion to be used may be used, and if the recess 12a is formed, the cross section is not limited to a U-shape. For example, even if the cross section is H-shaped , Type I may also be used.

Further, in the present embodiment, the example in which the support portion 53 is formed of H-shaped steel has been described. However, the support portion has a protruding shape and can be inserted into the recess 12a of the connection ring 12 to support the connection ring 12. For example, it may be formed of a steel material having a U-shaped cross section, an I-shaped steel, a steel bar, a square hollow steel pipe, or the like.
In the present embodiment, the lower flange portion 53b of the support portion 53 is formed to be shorter in the longitudinal direction than the upper flange portion 53a so as to be easily inserted into the recess 12a of the connecting ring 12. As described above, the upper and lower flange portions 53 a and 53 b may be formed to have the same length so that the projecting support portion 53 fits into the recess 12 a of the connecting ring 12. Thereby, the support of the liner plate 1 via the connection ring 12 by the support part 53 becomes more stable.

Further, as shown in FIG. 6, the support frame 5 may be provided with a rod-shaped fixing member 58 made of a pipe or the like driven into the ground. Through holes 56a and 57a are formed in an upper joining plate 56 and a lower joining plate 57 for joining the frame pieces 52 of the support frame 5 with squares, respectively. After the rod-shaped fixing member 58 is fitted into the through holes 56a and 57a, the supporting frame 5 is stably fixed on the ground by driving the fixing member 58 into the ground.
Thereby, positioning with respect to the shaft 2 of the liner plate 1 supported by the support frame 5 can be performed correctly, and the shift | offset | difference of a pile core can be suppressed.

  Further, in the present embodiment, the example in which the crane 80 is used in the drawing operation of the liner plate 1 has been described. For example, four hydraulic winch hooks are hooked on the lower edge of the liner plate 1 at approximately equal intervals. A pulling operation or the like may be performed by lifting the liner plate 1 using a hydraulic winch.

  Further, in the present embodiment, the example in which the liner plate units 11 are connected to each other by the bolt 6 and the nut 7 via the connection ring 12 has been described. However, the connection means is not limited to the bolt 6 and the nut 7, and the connection and connection are not limited. Any means can be used as long as the release is possible.

  Further, in the present embodiment, an example in which the base 51 of the support frame 5 is formed as a frame has been described. However, even if the base is not integrated, the support portion 53 can be provided and the shaft 2 can be excavated. As long as it is installed on the ground around the position, it may be a separate body.

  In the present embodiment, an example in which the four support portions 53 are provided has been described. However, a plurality of support portions 53 that can support the liner plate 1 may be used, and two or three support portions 53 may be provided. Or you may make it have five or more support parts 53. FIG.

In the present embodiment, the example in which the support portion 53 is detachably fixed to the frame piece 52 has been described. However, the support portion 53 is slidable in the direction toward the liner plate 1 and in the opposite direction. You may make it always fix to the frame piece 52. FIG. In this case, the guide hole 531b is formed longer in the longitudinal direction. By making the nut 9 loosely tightened on the bolt 8, the support portion 53 is slidable in the direction of the liner plate 1 and in the opposite direction.
For example, when the liner plate 1 is moved in the vertical direction at the excavation position of the shaft 2, the support portion 53 is slid to a position pulled away from the liner plate 1 so as not to be an obstacle.
Further, when the liner plate 1 is supported by the support portion 53 via the connection ring 12, the support portion 53 is slid to a position where it is inserted into the recess 12 a of the connection ring 12, and the nut 9 is tightened on the bolt 8. The support part 53 is firmly fixed to the frame piece 52.

Further, in the present embodiment, the example in which the support portion 53 is inserted and supported in the concave portion 12a of the connecting ring 12 has been described. However, the protruding support portion 53 is supplementarily provided with the concave portion 11a of each liner plate unit 11. (FIG. 4) may be inserted and supported. In this case, the support portion 53 is inserted into and abutted with the concave portion 11a of the liner plate unit 11, and is protruded in a shape that can be fitted into the concave portion 11a so that the liner plate unit 11 can be stably supported. The support part 53 may be formed.
Thereby, the liner plate 1 can be moved in the vertical direction at a finer distance at the excavation position of the shaft 2, and the shaft 2 can be excavated with high accuracy.

  In the present embodiment, the example in which the liner plate unit 11 is removed one by one in the operation of pulling out the liner plate 1 from the shaft 2 has been described. However, a plurality of liner plate units 11 are removed at a time. It may be.

DESCRIPTION OF SYMBOLS 1 Liner plate 11 Liner plate unit 11a Recessed part 12 Connection ring 12a Recessed part 12b Flange part 2 Vertical shaft 5 Support frame (support member)
51 Base 52 Frame piece 53 Supporting portion 53a Upper flange portion 53b Lower flange portion 531b Guide hole 53c Web portions 56, 57 Joining plate (joining plate)
56a, 57a Through hole 58 Fixing member 6, 8 Bolt 7, 9 Nut 80 Crane 110 Concrete

Claims (14)

A plurality of cylindrical liner plate units that are connected to the inner wall surface of the shaft to be excavated and can be pulled out from the shaft,
A liner plate provided with a connecting ring for connecting the liner plate units to each other, wherein the liner plate unit is fixed to an upper end of the liner plate unit, and a recess opening outward is formed.
The liner plate unit includes a plurality of projecting support portions provided around the excavation position of the shaft and on a base installed on the ground, and are inserted into the recesses of the connection ring. A liner plate which can be supported via a ring.   The liner plate according to claim 1, wherein the liner plate units can be connected to each other via the connecting ring and can be released outside the shaft.   3. The liner plate according to claim 1, wherein the support plate can be supported so as to be vertically movable at an excavation position of the shaft.   4. The liner plate according to claim 3, wherein the liner plate can be pulled out from the shaft by a predetermined distance in accordance with a predetermined height of the concrete placed in the shaft. 5. The base is formed as a frame by upper and lower joining plates in which through-holes are formed and frame pieces joined by the joining plates,
The liner plate according to any one of claims 1 to 4, wherein a plurality of rod-shaped fixing members are fitted into the through holes of the joining plate and driven into the ground.   The liner plate according to any one of claims 1 to 5, wherein a connecting ring for connecting the liner plate units to each other is fixed to the liner plate unit.   The liner plate according to any one of claims 1 to 6, wherein the support portion is formed of H-shaped steel, and the connection ring can be supported by an upper flange portion.   The liner plate according to any one of claims 1 to 7, wherein the connecting ring fixed to the upper end of the liner plate unit has a U-shaped cross section.   The liner plate according to claim 1, wherein the support portion is slidably provided on the base. The liner plate unit has a corrugated shape having a concave portion,
The liner plate according to any one of claims 1 to 9, wherein the liner plate unit can be supported by inserting the support portion into the concave portion. A step of excavating the shaft, a step of connecting a plurality of cylindrical liner plate units each having a connecting ring formed with an outwardly-opened concave portion fixed to the upper end through the connecting ring, A deep foundation method having a step of installing the connected liner plate unit on an inner wall surface,
A plurality of projecting support portions provided around the excavation position of the shaft and on a base installed on the ground are fixed to the upper end of the liner plate unit disposed at the excavation position of the shaft. Inserting into the recess of the connecting ring and supporting the liner plate unit via the connecting ring;
A deep foundation method comprising a step of connecting the liner plate unit supported by the support portion and the other liner plate unit via the connecting ring outside the shaft. Extracting the liner plate unit from the shaft,
The deep foundation method according to claim 11, further comprising a step of disconnecting the liner plate units by the connection ring outside the shaft.   The deep foundation method according to claim 11 or 12, wherein the liner plate unit is supported so as to be movable in a vertical direction at an excavation position of the shaft.   The deep foundation method according to claim 12, further comprising a step of extracting the liner plate unit from the shaft by a predetermined distance according to a predetermined height of the concrete placed in the shaft.

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