JP2017066836A - Core material for earth retaining wall and upper core material removing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To disengage an upper core member 12 by releasing the connection with a lower core member 11 in a core member 5 built in a retaining wall. SOLUTION: A connecting means 13 for connecting a lower core material (H-shaped steel) 11 and an upper core material (H-shaped steel) 12 includes outer surfaces and inner surfaces of excavation side flanges 11a and 12a, and natural ground side flanges 11b and 12b. First to fourth contact plates 21 to 24 that respectively contact the inner surface and the outer surface, first fixing means 25 for fixing the lower portion of the contact plates 21 to 24 and the lower core 11, 2nd fixing means 26 which fixes the upper part of the adjoining plates 21-24 and the upper side core material 12 is included. The second fixing means 26 includes, from the excavation side, the first attachment plate 21, the excavation side flange 12a, the second attachment plate 22, the third attachment plate 23, the natural mountain side flange 12b, and the first 4 including a long bolt 35 penetrating the four contact plates 24. Here, only the second attachment plate 22 has a screw portion 36 that is screwed with the long bolt 35. [Selection] Figure 3

Description

  The present invention relates to a core material for a retaining wall composed of a lower core material and an upper core material, and a method for removing the upper core material from the core material while leaving the lower core material.

When constructing an underground structure such as a tunnel structure, an earth retaining wall is constructed, and the interior is excavated while retaining the structure and retaining water.
In the construction of underground structures using earth retaining walls, for example, soil mortar soil that reaches the impermeable layer from the ground surface using SWM (Soil Mixing Wall) method or TRD (Trench cutting Re-mixing Deep wall) method. Build a retaining wall. In the construction of the earth retaining wall, a plurality of core materials made of H-section steel are built in parallel at intervals from each other in the soil mortar before hardening. After construction of the retaining wall (after the soil mortar has hardened), the excavation of the construction site will proceed. Then, an underground structure is constructed at the excavated construction site. After the construction of the underground structure, it will be backfilled.

Here, in urban areas, near the construction site of underground structures, road tunnel construction work and burial work such as communication cables, water pipes and gas pipes may be carried out in the future. Sometimes, in the core material, removal of a portion (upper portion) in a range from the ground surface to a depth at which future construction is expected may be required.
In such a case, as shown in Patent Document 1 or the like, a core material made of H-shaped steel for retaining walls is used as a connection structure of the lower core material and the upper core material, and the lower core material is backfilled at the time of backfilling. It is performed that the upper core material can be separated and removed.

  In particular, in the connection structure of the lower core material and the upper core material described in Patent Document 1, the outer core surface of the excavation side flange and the outer surface of the natural ground side flange are respectively straddled between the lower core material and the upper core material. An abutment plate (joining plate) is provided, and the long bolt is passed from the excavation side to the excavation side attachment plate, the excavation side flange, the natural ground side flange, and the natural ground side attachment plate, and the long bolt on the natural ground side The tip is screwed into a nut fixed to the natural ground side attachment plate and tightened.

In such a connection structure, at the time of backfilling (specifically, when backfilling to the vicinity of the connection position between the lower core material and the upper core material), the head of the long bolt is rotated from the excavation side to After releasing the screwing, the connection between the lower core member and the upper core member can be released by pulling out the long bolt. Thereby, the upper core material can be pulled out from the soil mortar on the ground surface side.
Accordingly, the connection between the lower core member and the upper core member can be released by the operation of pulling out the long bolt from the excavation side, and the upper core member can be easily removed.

Japanese Patent No. 3404315

However, the structure described in Patent Document 1 has the following problems because the nut into which the long bolt is screwed is located behind the natural mountain side flange.
A large external force may be applied to the long bolt when the core material is built in. As a result, the long bolt may be bent or the nut may be crushed, and the long bolt and the nut may not be released. In such a case, it is necessary to melt the screwed portion using a gas welding machine or the like. However, since the threaded part is at the back of the natural mountain side flange, it is necessary to break the earth retaining wall of the part from the excavation side to the natural mountain side for gas fusing, by breaking the earth retaining wall to the natural mountain side, There is a risk that the water stoppage may be impaired.

  The present invention has been made in view of such a situation, and it is easy to release the connection between the lower core material and the upper core material, and even when the screwing portion does not rotate, the earth retaining wall is broken so much. It is an object of the present invention to provide a core material for a retaining wall (a connection structure of a lower core material and an upper core material) that can be disconnected without any problem.

The core material for the retaining wall according to the present invention is:
A lower core made of an H-shaped steel and forming a lower part of the core;
The lower core material is made of H-section steel having the same cross-sectional shape, and the upper core material forming the upper part of the core material;
The first to first contact with the outer surface of the excavation side flange, the inner surface of the excavation side flange, the inner surface of the natural ground side flange, and the outer surface of the natural ground side flange in a form straddling the lower core material and the upper core material. A fourth accessory plate;
First fixing means for fixing a lower portion of the first to fourth attachment plates and the lower core member;
A second fixing means for fixing the upper part of the first to fourth attachment plates and the upper core member;
It is comprised including.
Here, the second fixing means is a long bolt having a head on the excavation side, and the long bolt is connected to the first attachment plate, the excavation side flange, the second excavation side from the excavation side. It penetrates through the attachment plate, the third attachment plate, the natural ground flange, and the fourth attachment plate. Of these penetrating parts, only the second attachment plate has a threaded part that engages with the long bolt.

According to the present invention, from the excavation side, after turning the head of the long bolt to release the threaded engagement with the screw portion of the second attachment plate, the step of pulling out the long bolt; The upper core material can be removed in the process of pulling out the upper core material from the ground surface side of the retaining wall.
That is, the operation of pulling out the long bolt from the excavation side can release the connection between the lower core material and the upper core material, and the upper core material can be easily removed.
Moreover, even when it becomes impossible to release the screwing between the long bolt and the screw part, the screwing part is located on the excavation side flange. It is enough to break only. Therefore, the connection can be released without much breaking the earth retaining wall, and there is little risk of impairing the water stoppage.

The figure which shows the construction example of the underground structure using the earth retaining wall as one Embodiment of this invention Top view of the retaining wall of the above construction example Front view of the connecting portion of the core material corresponding to the enlarged view of the portion X in FIG. Top view of the connecting part Front view of connecting part showing modification 1 The top view of the connection part which shows the modification 2

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a construction example of an underground structure using a retaining wall as one embodiment of the present invention. FIG. 2 is a top view of the retaining wall of the construction example same as above, (A) shows a columnar retaining wall by the SMW method, and (B) shows an equal thickness retaining wall by the TRD method.

When constructing and constructing an underground structure (buried frame) 2 under the ground 1, prior to this construction, the retaining wall 3 is constructed for the purpose of retaining and stopping the water at the construction site.
Therefore, the earth retaining wall 3 partitions the excavation side (scheduled excavation area) of the ground 1 from the natural ground side (non-excavation area).
In this embodiment, the earth retaining wall 3 is a soil mortar. In the present embodiment, a pair of retaining walls 3 are also provided facing each other so as to sandwich the construction site from both sides thereof. Therefore, the construction site is partitioned by the retaining wall 3.

When using the SMW method, etc., as the construction method of the retaining wall 3, drill the ground with a multi-shaft kneading auger, discharge cement milk as a solidifying agent from the tip, mix and agitate with excavated soil (Soil) (Mixing) A soil mortar wall body (Wall) 4 is formed, and this is repeated to form a columnar continuous wall in the ground (see FIG. 2A).
Also, when using the TRD method, etc., move the chainsaw-type cutter post built in the ground in the lateral direction, excavate the groove, inject cement milk, mix and agitate with the excavated soil. Then, a wall 4 made of soil mortar is formed in the ground, and in this construction method, a constant-thickness type continuous wall is formed (see FIG. 2B).

In the earth retaining wall 3, a core material (pile) 5 extending in a vertical direction is built inside the wall body 4 of the soil mortar by the SMW method or the TRD method before the soil mortar is hardened. Here, a plurality of core members 5 are built in the continuous direction of the wall body 4 at a predetermined interval.
Therefore, the earth retaining wall 3 includes a soil mortar wall body 4 and a plurality of core members 5 arranged in a line at a predetermined interval in the continuous direction of the wall body 4.

  The core material 5 is basically made of an H-shaped steel. Accordingly, the core member 5 is composed of a pair of front and rear flanges that are parallel to each other and a web that connects the center portions of both flanges. An I-shaped steel is similar to the H-shaped steel. This is only a relatively short flange compared to the H-section steel. Therefore, even if it is called an I-shaped steel, if it has a pair of front and rear flanges that are parallel to each other and a web that connects the central portions of both flanges, the “H-shape” referred to in the present invention is used. Included in “steel”.

  The core material 5 is also divided into a lower core material (lower H-shaped steel) 11 and an upper core material (upper H-shaped steel) 12, and a connection structure between the lower core material 11 and the upper core material 12. It has become. Accordingly, the core material 5 includes the lower core material 11, the upper core material 12, and the connecting means 13 that connects the upper end portion of the lower core material 11 and the lower end portion of the upper core material 12. .

The lower core 11 is an H-shaped steel, and includes a pair of front and rear flanges 11a and 11b and a web 11c that connects the center portions of both flanges 11a and 11b.
The upper core member 12 is an H-section steel having the same cross-sectional shape as the lower core member 11, and is composed of a pair of front and rear parallel flanges 12a and 12b and a web 12c that connects the center portions of both flanges 12a and 12b. .

As for the core material 5 (lower core material 11 and upper core material 12) made of H-shaped steel, a pair of front and rear flanges (11a, 12a and 11b, 12b) are mutually connected in the thickness direction of the retaining wall 3. It is installed in the earth retaining wall 3 so as to face each other. Therefore, one flange 11a, 12a becomes an excavation side flange, and the other flange 11b, 12b becomes a natural ground side flange.
In addition, about the two core materials 5 adjacent to the continuous direction of the earth retaining wall 3, earth retaining so that mutual webs (11c, 12c and 11c, 12c) may face each other in the continuous direction of the earth retaining wall 3 It is installed in the wall 3.

The earth retaining wall 3 (the wall body 4 made of soil mortar) is constructed so as to reach the impermeable layer from the surface of the ground 1.
The length of the core material 5 in the longitudinal direction (that is, the length of the retaining wall 3 in the height direction) is such that the lower end of the core material 5 reaches slightly below the flooring surface (bottom surface of excavation) 6 at the construction site. Is set based on the stress calculation.
Regarding the length in the longitudinal direction of the upper core member 12 (that is, the length in the height direction of the earth retaining wall 3), the core member 5 is required to be removed after the underground structure 2 is built and backfilling is completed. Is set based on the depth to be played.

Next, the connecting means 13 for the core material 5 (the lower core material 11 and the upper core material 12) will be described with reference to FIGS.
FIG. 3 is a front view (cross-sectional view taken along line FF in FIG. 4) of the connecting portion of the core member 5 corresponding to the enlarged view of the portion X in FIG. 1, and FIG. In FIG. 3 and FIG. 4, the illustration of the earth retaining wall 3 (the wall body 4 of the soil mortar) is omitted for simplification.

  The connecting means 13 includes first to fourth attachment plates 21 to 24, first fixing means 25 for fixing the lower portion of the first to fourth attachment plates 21 to 24 and the lower core member 11. The second fixing means 26 for fixing the upper portions of the first to fourth attachment plates 21 to 24 and the upper core member 12 are included.

The first attachment plate 21 is applied to the outer surfaces of the excavation side flanges 11 a and 12 a so as to straddle the lower core material 11 and the upper core material 12.
The second attachment plate 22 is applied to the inner surfaces of the excavation side flanges 11 a and 12 a so as to straddle the lower core material 11 and the upper core material 12.
The 3rd attachment board 23 is applied to the inner surface of the natural ground side flanges 11b and 12b in the form straddling the lower side core material 11 and the upper side core material 12. As shown in FIG.
The fourth attachment plate 24 is applied to the outer surfaces of the natural ground flanges 11b and 12b so as to straddle the lower core member 11 and the upper core member 12.
Although the first to fourth attachment plates 21 to 24 are shown in a flat plate shape in the drawing, they may have appropriate reinforcing ribs or the like for improving the strength.

The first fixing means 25 includes a first bolt / nut (which fixes the lower part of the first attachment plate 21, the excavation side flange 11 a of the lower core 11, and the lower part of the second attachment plate 22 ( Bolts 31 and nuts 32), second bolts and nuts for fixing the lower portion of the third attachment plate 23, the ground-side flange 11b of the lower core member 11, and the lower portion of the fourth attachment plate 22; A bolt 33 and a nut 34). The nuts 32 and 34 may be fixed to the second and fourth attachment plates 22 and 23 by welding or the like.
However, since it is not necessary to attach and detach the lower core material 11 and the first to fourth attachment plates 21 to 24, the first fixing means 25 may be anything, and it is fixed by welding. You may make it do.

The second fixing means 26 includes a long bolt 35 having a head on the excavation side.
The long bolt 35 extends from the excavation side to the upper part of the first attachment plate 21, the excavation side flange 12a of the upper core member 12, the upper part of the second attachment plate 22, the upper part of the third attachment plate 23, and the upper side. It penetrates the natural mountain side flange 12 b of the core material 12 and the upper part of the fourth attachment plate 24.
Here, of these through portions, only the second attachment plate 22 has a screw portion (screw hole) 36 that is screwed with the screw portion 35 a of the long bolt 35.
That is, the long bolt 35 penetrating portion of the first attachment plate 21 and the excavation side flange 12a is a bolt insertion hole through which the long bolt 35 is inserted. Further, the long bolt 35 penetrating portions of the third attachment plate 23, the natural mountain side flange 12 b and the fourth attachment plate 24 are also bolt insertion holes through which the long bolts 35 are inserted.
Therefore, the long bolt 35 slidably penetrates the first attachment plate 21 and the excavation side flange 12a and is screwed into the second attachment plate 22, and further, the third attachment plate 23, The natural mountain side flange 12b and the fourth attachment plate 24 are slidably penetrated.

The long bolt 35 may be formed with a screw up to the tip, but may have a screw portion 35a at a position corresponding to the screw portion (screw hole) 36 of the second attachment plate 22. The tip side from 35a may be a straight pin shape.
That is, the front end side of the long bolt 35 is a connecting pin portion 35b that fits loosely so that it can be inserted and removed with respect to the ground-side flange 12b of the upper core member 12 and the third and fourth attachment plates 23 and 24 before and after the flange 12b. I am doing.

  In the above connecting structure, the lower core member 11 and the first to fourth attachment plates 21 to 24 are fastened by normal bolts 31 and 33 and nuts 32 and 34. In the first to fourth attachment plates 21 to 24 and the upper core member 12, the screw portion 35 a of the long bolt 35 is a screw of the second attachment plate 22 on the excavation side flange 12 a side of the upper core member 12. The upper core member 12 can be fastened and fixed between the first and second attachment plates 21 and 22 by being screwed into the portion (screw hole) 36. In addition, the first to fourth attachment plates 21 to 24 and the upper core member 12 are connected to the ground pin side flange 12b of the upper core member 12 by connecting the connecting pin portion 35b of the long bolt 35 to the ground mountain side flange 12b. By fitting the front and rear third and fourth attachment plates 23 and 24, these can be integrally connected.

  Next, the core material 5 (the lower core material 11 and the upper core material 12) having the connection structure as described above is built to complete the earth retaining wall 3, and the inside thereof is excavated to form the underground structure 2 A method of removing the upper core material 12 while leaving the lower core material 11 from the earth retaining wall 3 when backfilling after construction will be described.

When the backfilling is completed to the vicinity of the connection portion between the lower core member 11 and the upper core member 12, a part of the soil mortar on the excavation side of the retaining wall 3 is broken, and the head of the long bolt 35 is exposed.
In this state, the head of the long bolt 35 is rotated to release the screwing with the screw portion 36 of the second attachment plate 22, and then the long bolt 35 is pulled out. At this time, since the long bolt 35 is only loosely fitted to the natural mountain side flange 12b and the third and fourth attachment plates 23 and 24 before and after the flange 12b, the drawing is easy.
By pulling out the long bolt 35, the connection between the upper core member 12 and the first to fourth attachment plates 21 to 24, that is, the connection between the upper core member 12 and the lower core member 11 can be released (edge cutting). .

  Even if the long bolt 35 and the threaded portion 36 of the second attachment plate 22 cannot be released, the screwed portion is located on the excavation side flange 12a. Therefore, it is sufficient to break only the excavation side of the earth retaining wall 3 (wall body 4) of the part. Accordingly, the connection can be released without damaging the earth retaining wall 3 so much that there is little risk of impairing the water stoppage.

After releasing the connection between the lower core 11 and the upper core 12 by pulling out the long bolt 35, from the ground surface side, the upper core is pulled by a puller (reversing the press-fitting machine), jack, or wire pulling using a multi pulley. The core member 12 is pulled up and pulled out from the earth retaining wall 3.
At this time, if the first to fourth attachment plates 21 to 24 are left on the lower core member 11 side, only the upper core member 12, that is, only the H-section steel having the same cross-sectional shape from the top to the bottom is pulled up. Since it is good, the pull-out resistance can be kept extremely small.

Next, a modification to the above embodiment will be described.
FIG. 5 is a front view of the connecting portion showing the first modification.
In this example, instead of providing a threaded portion (screw hole) in the second attachment plate 22, a nut 37 is fixed to the bolt insertion hole by welding or the like. Therefore, the thread portion of the second attachment plate 22 is constituted by the nut 37 fixed to the second attachment plate 22.

FIG. 6 is a plan view of a connecting portion showing a second modification.
In this example, the second attachment plate 22 and the third attachment plate 23 are connected to each other by a connecting portion 38 and are formed in a U-shaped cross section as a whole. Thereby, the intensity | strength of a connection structure can be improved.

  The illustrated embodiments are merely examples of the present invention, and the present invention is not limited to those directly described by the described embodiments, and various improvements and modifications made by those skilled in the art within the scope of the claims. Of course, it encompasses changes.

  In the illustrated embodiment, eight short bolts and four long bolts are used for the connecting portion between the lower core member 11 and the upper core member 12, but this is simply the number determined in the drawing. Needless to say, this is different from the actual number used.

DESCRIPTION OF SYMBOLS 1 Ground 2 Underground structure 3 Earth retaining wall 4 Wall body of soil mortar 5 Core material (H-section steel)
6 Flooring surface of construction site (bottom surface of excavation)
11 Lower core (H-section steel)
11a Excavation side flange 11b Natural ground side flange 11c Web 12 Upper core material (H-section steel)
12a Excavation side flange 12b Ground mountain side flange 12c Web 13 Connecting means 21 First attachment plate 22 Second attachment plate 23 Third attachment plate 24 Fourth attachment plate 25 First fixing means 26 Second Fixing means 31, 32 First bolt / nut 33, 34 Second bolt / nut 35 Long bolt 35a Threaded portion 35b Connecting pin portion 36 Threaded portion (screw hole) of second attachment plate
37 Nut 38 Connection

Claims (6)

A core material built into a retaining wall that separates the excavation side and the natural mountain side of the ground,
A lower core made of an H-shaped steel and forming a lower part of the core;
The lower core material is made of H-section steel having the same cross-sectional shape, and the upper core material forming the upper part of the core material;
The first to first contact with the outer surface of the excavation side flange, the inner surface of the excavation side flange, the inner surface of the natural ground side flange, and the outer surface of the natural ground side flange in a form straddling the lower core material and the upper core material. A fourth accessory plate;
First fixing means for fixing a lower portion of the first to fourth attachment plates and the lower core member;
A second fixing means for fixing the upper part of the first to fourth attachment plates and the upper core member;
Comprising
The second fixing means is a long bolt having a head on the excavation side,
The long bolts are arranged from the excavation side to the first attachment plate, the excavation side flange, the second attachment plate, the third attachment plate, the ground mountain side flange, and the fourth attachment plate. Penetrate the plate,
Of these penetrating parts, only the second attachment plate has a threaded part that engages with the long bolt, and a core material for a retaining wall.   The long bolt has a threaded portion at a position corresponding to the threaded portion of the second attachment plate, and the distal end side of the long bolt has a straight pin shape. Core material for earth retaining walls.   The core material for a retaining wall according to claim 1 or 2, wherein the thread portion of the second attachment plate is a nut fixed to the second attachment plate.   The second attachment plate and the third attachment plate are connected to each other and formed in a U-shaped cross section as a whole. Core material for retaining walls as described in 1.   The first fixing means includes a first bolt / nut for fixing the first attachment plate, the excavation side flange, and the second attachment plate, the third attachment plate, and the ground side. The earth retaining wall according to any one of claims 1 to 4, comprising a flange and a second bolt and nut for fixing the fourth attachment plate. Core material. A method of removing the upper core material from the core material according to any one of claims 1 to 5, which is built in the retaining wall, leaving the lower core material.
From the excavation side, turning the head of the long bolt, releasing the screwing with the screw portion of the second attachment plate, and then pulling out the long bolt;
Extracting the upper core from the ground surface side of the earth retaining wall;
A method for removing the upper core material, including: