JP2947706B2 - Bridge pier construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to lower the lower end of a cast-in-place open caisson skeleton, which is the foundation of a pier, to a support layer below the riverbed, and after the foundation is constructed, to stop water on the foundation until the pier is completed. The present invention relates to a method of constructing a pier using a structure of an open caisson skeleton composed of precast concrete blocks for temporary water stoppage walls.

[0002]

2. Description of the Related Art In general, a well is known as a basis to which the principle of well digging is applied. The wells are formed by successively extending upwards, and are formed of a reinforced concrete frame (hereinafter referred to as an open caisson frame) sunk into the ground, and concrete and gravel filled therein. Things.

[0003] When forming the well, first, an open caisson frame for one lot (node) is formed by casting concrete, for example, at a place where a foundation is to be provided. At this time, a sharp cutting edge is provided on the lower surface of the open caisson body. Then, by excavating the inside of the open caisson frame, the open caisson frame is sunk into the ground by its own weight.

[0004] Then, the open caisson frame for the next lot is formed on top of the settled open caisson frame for the next lot, and the inside of the open caisson frame is excavated again, so that the open caisson frame by its own weight. It is further submerged in the ground. Then, successively, a new lot of open caisson skeletons are added to the sunk open caisson skeletons to form and sink. Then, when the open caisson skeleton is formed to the required depth, the inside of the open caisson skeleton is filled with concrete, gravel, or the like to form a foundation.

In recent years, the open caisson frame (for one lot) is not made of cast-in-place reinforced concrete but made of precast concrete (hereinafter abbreviated as PC) as shown in FIG. 1 and this open caisson frame 1 made of PC
There is a case where a method of building a foundation by stacking and sinking is performed.

By using the above-mentioned open caisson skeletons 1 made of PC, it is not necessary to cast and cure concrete at the construction site of the foundation, and the workability of foundation construction can be improved. Further, by using the PC-made open caisson skeleton 1, no concrete curing period is required at the construction site, so that the construction period can be greatly reduced.

[0007]

The above-mentioned well is used, for example, as a base part of a pier of a bridge constructed on a river. Then, in the city area or in the vicinity of the city area, the base portion of the pier may be constructed using the well. However, in a case where a large-sized open caisson frame made of PC is used in the above-mentioned urban area or the like, there are the following problems.

That is, in an urban area or the like, a general large truck capable of traveling in an urban area is used to transport an open caisson frame made of PC from a production site to a bridge construction position. The weight and size of the conveyed object are limited, and it is difficult to convey a large PC open caisson frame from the production site of the open caisson frame to the bridge construction site.

In addition, in the vicinity of a bridge construction site such as an urban area,
It is also difficult to secure a place to produce the PC open caisson. That is, in order to produce a large open caisson made of PC, a large site corresponding to the large site is required, and it is not always possible to secure such a large site near a bridge construction site in an urban area. Therefore, the bridge construction site and P
It is difficult to make the open caisson frame made of C adjacent to the production site. Further, it is difficult to transport and install a large crane or the like for handling a large PC open caisson frame in an urban area.

A special method is required for transporting a large open caisson made of PC that cannot be transported by a large truck, even in an urban area. Implementing is difficult.

[0011] Therefore, the well using the frame-shaped open caisson frame made of PC of the above-mentioned conventional example has a small diameter of the well itself and can be transported by a large truck. PC adjacent to the construction site
Can secure a place to produce an open caisson made of
At present, it can be used only in a special environment such as a place where a large open caisson can be transported by a ship or the like.

The present invention has been made in view of the above circumstances, and even when the large open caisson frame is made of a PC structure, the handling of the PC structure, such as transportation, is facilitated. To provide a method of constructing a bridge pier using an open caisson structure that enables a large foundation, a water blocking wall, a closing wall, and the like to be constructed with an open caisson structure made of a PC structure at any place. It is intended for.

According to a first aspect of the present invention, there is provided a method for constructing a pier, wherein the frames are constructed in a tubular shape by connecting the frames up and down, and each of the frames is formed by dividing the frames by a substantially vertical dividing plane. A method for constructing a pier using an open caisson skeleton formed by connecting precast concrete blocks of a plurality of divided shapes in the circumferential direction as a temporary waterproof wall, and a cast-in-place open caisson skeleton serving as a foundation of the pier. The open caisson frame consisting of the precast concrete blocks is built up sequentially on the above-mentioned cast-in-place open caisson frame, and is also built in place by excavating the cast-in-place open caisson frame. The open caisson frame is settled, and then the cast-in-place open caisson frame is used as the foundation for the pier. And performing the build piers open caisson building frame body made of cast concrete block.

According to a second aspect of the present invention, there is provided the pier construction method according to the first aspect.
Grout material is cast between the adjacent precast concrete blocks on the left and right so that the inside of the frame is in a water-blocking state, and the water-blocking material is placed on the top surface of the precast concrete block, and the upper and lower precast concrete blocks The prevention of water leakage between the blocks made of the steel is a means for solving the above-mentioned problem.

Further, according to a third aspect of the present invention, there is provided the pier construction method according to the first or second aspect, wherein the cut-off wall is filled with earth and sand, and the pier is filled on the earth and sand. The construction of a base cast-in-place open caisson skeleton was the solution to the above problem.

[0016]

According to the structure of the first aspect, the frame is formed by connecting the blocks made of the PC having a shape obtained by dividing the frame into a plurality of pieces in the weekly direction. The weight and size of the PC block can be transported by a transport vehicle such as a normal truck without the difficulty of transporting the open caisson frame. The open caisson frame can be easily transported from the member production site to the installation site of the open caisson frame.

In addition, since the weight and size of the PC block constituting the open caisson frame can be transported by truck as described above, a general crane is also used for lifting the PC block. be able to. Therefore, even if the open caisson frame is made of PC, it is possible to install the open caisson frame without any special vehicle or equipment.

When the pier is completed, the open caisson frame as the temporary water stop wall is removed. In this case, the open caisson frame is easily disassembled as compared with the integrated cast-in-place open caisson frame. Can be
Removal work with a crane or the like can be facilitated.

Further, the removed PC block of the open caisson frame can be reused as long as the strength is not reduced by the removal work or the like, and the PC block can be used for other temporary water stop walls and other uses. It can be diverted and cost can be reduced.

According to the method for constructing a pier according to claim 2,
The upper, lower, left and right P
Since the block made of C is completely stopped by the joining of the blocks made of C, water leakage from the earth and sand in the cutoff wall does not enter the open caisson body.

Further, even if the earth and sand and the sheet pile in the cutoff wall are removed, water leakage into the open caisson body can be prevented.

According to the method of constructing a pier according to claim 3,
After lowering the conventional cast-in-place open caisson frame from the top of the earth and sand inside the cut-off wall to a predetermined depth, the open cast-in caisson frame composed of the PC block is built up sequentially on the cast-in-place open caisson frame. As it moves, the cast-in-place open caisson structure is lowered, and an open caisson structure made of PC blocks can be constructed until the lower end of the cast-in-place open caisson structure reaches the support layer of the riverbed.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for constructing a pier using an open caisson frame structure formed from a PC block according to the present invention will be described below with reference to the drawings. FIG. 1 to FIG. 3 show the structure of an open caisson frame 10 formed from a PC block of this embodiment. In addition,
In this embodiment, an open caisson frame is not used as a base but as a temporary water stop wall as described later.

The left half of the open caisson frame 10 shown in FIG. 1 shows a cross section taken along the line AA in FIG.
FIG. 2B shows a side view, in which the left half of the open caisson frame 10 in FIG. 2 shows a cross section taken along the line CC in FIG.
A cross section is shown, and FIG. 3 is a development view of the open caisson frame 10. As shown in FIGS. 1 to 3, the open caisson frame 10 of this embodiment is formed in a cylindrical shape. And the open caisson frame 10
The open caisson frame 10 is composed of a plurality of frames 11 which are vertically divided into a plurality of parts (annular in plan view). Further, the frame bodies 11 are composed of PC blocks 12 each having a shape (an arc shape in plan view) obtained by dividing the frame bodies 11 into a plurality of sections along a radially dividing plane.

Also, as shown in FIGS. 1 and 3, between the vertically adjacent frames 11, the right and left sides of the joints of the PC blocks 12 constituting the frames 11 are alternated. (Ie, the joint between the PC blocks 12 of the upper frame 11 and the PC block 1 of the lower frame 11).
2) Make sure that the joints between them are not on a straight line) PC
Blocks 12 are arranged.

FIGS. 4 to 7 show the PC block 1 described above.
FIG. The PC block 12 shown in FIG.
5 shows the EE plane of FIG. 5, the right half shows the FF section, and the left half of the PC block of FIG.
G inner surface, the upper right half shows the HH cross section of FIG. 4, the lower right half shows the II cross section of FIG. 4, and FIG. 6 shows the JJ side surface of FIG. FIG. 7 shows a KK cross section of FIG.

As shown in FIGS. 4 to 7, the PC block 12 is a PC plate curved in an arc shape. The PC block 12 has a shape obtained by dividing the cylindrical frame 11 along a radial direction and along a vertical division surface, and joining the PC blocks 12 along the circumferential direction. The frame 11 can be formed.

Each PC block 12 is designed to be conveyable on at least a general large truck with a weight and size. The PC block 12
Are joint surfaces 13 between the PC blocks 12 when the frame 11 is formed.

Further, the upper and lower end surfaces of the PC block 12 serve as joint surfaces 14 between the frames 11 when the open caisson frame 10 is constructed. Also, the above PC
Recesses 15, 15 are formed on both left and right end surfaces (connection surfaces 13, 13) of the block 12 along the vertical direction.

When connecting the PC blocks 12 along the circumferential direction, one of the PC blocks 12 connected to each other is connected in order to widen the allowable error range of the shape of the PC blocks 12. The connection surface 13 and the other connection surface 13 are joined with a space therebetween.

The space between the connection surfaces 13, 13 and the recesses 15, 15 are filled with a grout material such as non-shrink mortar or cement milk to reinforce the connection by the connection member S described later, and to make PC. Block 12, 1
The connection between the two is made more water-tight.

On the upper surface of the PC block 12, a groove 16 is formed at a position above the inner surface along the circumferential direction (the length direction of the PC block 12). And
As shown in FIG. 8 which is an enlarged view of a portion R in FIG. 6, a rubber waterproof material 17 is attached along the groove 16 inside the groove 16. And this waterproof material 17
Frame 11 composed of PC blocks 12.
.. Are designed to increase the water stoppage of the joint between them.

In the PC block 12, FIG.
As shown in FIGS. 5 and 7, the reinforcing bars 18 are arranged in a state of being buried in concrete, and
Connection members S are embedded in the upper, lower, left, and right ends of the connection member 2.
Then, as shown in FIG. 4, a first connection member LR1 for right and left connection is arranged at one end (left end in FIG. 4) of the left and right ends of the PC block 12, and the other end is provided. The second connecting member L is attached to the end (the right end in FIG. 4).
R2 ... are arranged.

As shown in FIG. 5, a first connection member TU1 for vertical connection is disposed at one of the upper and lower ends of the PC block 12 (the lower end in FIG. 5). The second connection member TU2 is disposed at the other end (the upper end in FIG. 5). As shown in FIG. 6, four connecting members S are arranged on the left and right connecting surfaces 13, 13 of the PC block, and two connecting members S, among these four connecting members S, are arranged. S is
The other two connecting members S, S are arranged above and below the inner peripheral side of the connecting surfaces 13, 13, and are arranged above and below the outer peripheral side of the connecting surfaces 13, 13.

That is, on the left and right connection surfaces 13 of the PC block 12, connection members S are arranged on the inner peripheral side edge and the outer peripheral side edge. FIG.
Is a drawing in which the inner peripheral surface of the frame 11 is developed.
At the right and left joints of the PC blocks 12,..., The PC blocks 12, 12 are connected by two upper and lower connecting members S, S.

As shown in FIG. 9, in the upper and lower connecting portions of the PC block 12, the connecting member S on the left side of the upper PC block 12 is connected to the connecting member S on the right side of the lower PC block 12. Is connected to the upper PC block 1.
2 is connected to the left connecting member S of the lower PC block 12 and the PC is connected between the upper and lower frames 11.
The blocks 12 are to be connected alternately.

FIGS. 10 to 12 show a connecting member S for connecting the upper and lower PC blocks 12 and 12 together. As shown in FIGS. 11 and 12, the upper and lower connecting members S are a first connecting member TU1 embedded in one PC block 12 of the two PC blocks 12 to be connected, and the other. And the second connection member TU2 embedded in the PC block.

The first connection member TU1 has a rectangular parallelepiped box-like member 20 with a hollow inside, and is welded to the left and right side surfaces of the box-like member 20, respectively, and extends rearward of the box-like member 20. It comprises two reinforcing bars (extending members) 21, 21.

In the upper and lower connecting members S,
The entire side surface of the box-shaped member 20 of the first connection member TU1 is an opening 22. When the box-shaped member 20 of the first connection member TU1 is embedded in the PC block 12, the opening 22 is exposed on the inner surface of the PC block 12, that is, the box 22 is opened by the opening 22. The inside of the shaped member 20 and the outside of the PC block 12 are in communication with each other.

In the opening 22, a connecting bolt 23 to be described later can be tightened. The tip end surface of the box-shaped member 20 is arranged so as to be substantially flush with the lower surface of the PC block 12 and is exposed. A through-hole (not shown) that penetrates the bolt 23 is formed at the center of the distal-side plate member 24 that forms the distal end surface of the box-shaped member 20.

The inside of the box-shaped member 20 and the outside of the PC block 12 communicate with each other through the through holes. The two rebars 21, 21 are bent in such a manner that their rear ends spread outward, respectively, and are formed in an L-shape. The reinforcing bars 21 and 21 increase the strength against the pull-out stress applied to the first connection member TU1, and smoothly transmit the bending moment between the PC blocks 12.

The second connecting member TU2 of the upper and lower connecting members S is formed by welding a flange 25 having a shape obtained by cutting a short angled steel material into a short shape, and is vertically welded to the inner surface of the flange 25. And a reinforcing bar (extending member) 27 screwed to the rear end of the cylindrical portion 26.

The flange portion 25 is formed integrally with two plate members perpendicular to each other in an L-shaped cross section.
8, a through hole (not shown) through which the bolt 23 penetrates is formed. Then, a portion around the through hole of the plate body 28 and a distal end portion of the cylindrical portion 26 are welded, so that the through hole and the screw hole of the cylindrical portion 26 are in communication.

The flange portion 25 is formed in the PC block 12 such that the outer surface of the plate body 28 to which the cylindrical portion 26 is welded on the inner surface side is substantially flush with the connection surface 14 of the PC block 12. Buried in Further, the plate 28
The position of the through hole is determined by the connection surface 1 of the PC block 12.
4, when the first connection member TU1 of the other PC block 12 abuts against the connection surface 14 in which the first connection member TU1 is embedded, the position substantially coincides with the position of the through hole of the box-shaped member 20 of the first connection member TU1. Have been.

Then, when the connection surfaces 14 of the two PC blocks 12 abut against each other as described above, the through-hole of the box-shaped member 20 of the first connection member TU1 and the second connection member TU
One bolt 23 can pass through the through hole of the second flange 25 at the same time.

The cylindrical portion 26 has a screw hole (not shown) inside as described above.
6 through the upper and lower ends. Reinforcing bar 27
Has a threaded portion formed at the tip end thereof, is screwed to the rear end of the cylindrical portion, and the rear end of the reinforcing bar 27 is bent in an L-shape.

The reinforcing bar 27 of the second connecting member TU2 has the same strength as the reinforcing bars 21 and 21 of the first connecting member TU1 with respect to the strength against the pull-out stress applied to the second connecting member TU2 and the PC block. The bending stress between 12, 12 is smoothly transmitted.

Then, as described above, the connection surfaces 14 and 14 of the two PC blocks 12 and 12 are abutted, and the through-hole of the box-shaped member 20 of the first connection member TU1 and the connection hole of the second connection member TU2 are formed. In a state where the position of the flange portion 25 is aligned with the through hole, the bolt 23 passes through the plate 24 of the box-shaped member 20 and the plate 28 of the flange 25 via the washer 29, and is screwed into the cylindrical portion 26. As a result, the first connection member TU1 and the second connection member TU2 are fastened to the bolt 23 and joined.

FIGS. 13 and 14 show the connecting members S for left and right.
It shows. As shown in FIGS. 13 and 14, the left and right connecting members S are composed of a first connecting member LR1 and a second connecting member LR2, like the above-mentioned up and down connecting members S. First connection member L of left and right connection member S
R1 is a rectangular box-shaped member 20 having a hollow inside.
Rebars (extending members) 21, 2 welded to the left and right side surfaces of the box-shaped member 20 and extending rearward of the box-shaped member 20.
It consists of one. Since the box-shaped member 20 and the reinforcing bar 21 have basically the same configuration as that of the upper and lower connection members S, the same reference numerals are given to the same components in the drawings, and the description thereof will be omitted. I do.

The second connection member LR2 of the left and right connection members
Is a flange portion 25 formed by cutting an angled steel material into a short shape, a tubular portion 26 which is vertically welded to the inner surface of the flange portion 25 and has a screw hole (not shown) therein; And a reinforcing bar (extending member) 27 screwed to the rear end portion. The flange portion 25 and the cylindrical portion 26
Since the reinforcing bars 27 have basically the same configuration as that of the upper and lower connecting members S, the same reference numerals are given to the same components in the drawings, and the description thereof will be omitted.

FIGS. 15 to 17 show a cast-in-place open caisson frame (a part of which is shown in FIGS. 15 to 17).
1 and 2 show a joining structure for joining the open caisson frame 10 including the PC block 12.

In this embodiment, since the open caisson frame 10 composed of the PC blocks 12... Is arranged on the cast-in-place open caisson frame 30 as described later,
A structure that joins the open caisson frame 10 composed of the PC block 12 and the PC block 12 is required.

And the cast-in-place open caisson frame 3
0 and an open caisson frame 10 composed of PC blocks 12 are shown in FIG. 15 to FIG. In FIGS. 15 to 17, the first connection member TU1 on the PC block 12...
0 to those shown in FIG.

Then, the cast-in-place open caisson frame 3
When the PC blocks 12 are placed on the upper surface of the
At a position facing the first connection member TU1, a box punching portion 31 is provided.
Are formed. The box emptying portion 31 is a concave portion for burying the anchor bolt 32.

When the PC block 12 is placed on the cast-in-place open caisson frame 30, the inner surface of the PC block 12 is placed in the cast-in-place open caisson frame 30.
Outside of the inner surface of. That is, under the inner surface of the PC block 12, the upper surface of the cast-in-place open caisson frame 30 is exposed.

The box punching portion 31 has a shape in which a portion facing the first connection member TU1 is dug down vertically, and an inner surface of the cast-in-place open caisson frame 30 of the inner surface. The slope 33 (see FIG. 17) in which the box-extracted portion 31 becomes wider as the surface corresponding to
), And the opening of the box emptying portion 31 is P
The C block 12 is exposed to the inside from the inner surface.

That is, with the PC block 12 placed on the cast-in-place open caisson frame 30, the opening of the box opening 31 on the upper surface of the cast-in-place open caisson frame 30 is completely closed by the PC block 12. Without
Partially open. The anchor bolt 32 has a threaded upper end,
The lower end is bent and is in a horizontal state.

Then, in the box punching section 31 having the above-described configuration, the box punching section 31 is opened in the box punching section 31 with the PC block 12 placed on the cast-in-place open caisson frame 30. The anchor bolt 3
2 and the upper end of the anchor bolt 32 is inserted into the through-hole of the box-shaped member 20 of the first connection member TU1, and the upper end of the anchor bolt 32 is used for bolt operation of the first connection member TU1. A nut 34 is inserted through the opening 22 and screwed together, so that the anchor bolt 32 is disposed substantially vertically in the boxed portion 31.

Then, in this state, the non-shrink mortar is filled from the open portion of the box punching portion 31 so that the anchor bolt 32 is fixed to the cast-in-place open caisson frame 30 and the anchor bolt 32 is used to fix the place. The striking open caisson frame 30 and the PC block 12 are fixed.

Next, a method of constructing a temporary water stoppage wall using the structure of the open caisson frame 10 composed of the PC blocks 12 will be described. In this embodiment, as shown in FIG. 1, a cut-off wall 37 is formed by a sheet pile 36 at the base of a pier of a bridge to be constructed in a river 35.
And filling the cut-off wall 37 with earth and sand 38,
8, a conventional cast-in-place open caisson frame 30 is used to construct the foundation of the pier.

The upper end of the foundation provided by the cast-in-place open caisson frame 30 is below the water surface of the river 35, and a pier is provided on the foundation below the water surface. In this embodiment, the lower end of the cast-in-place open caisson frame 30 is lowered to the support layer below the riverbed, and after the foundation is constructed, a temporary water stop wall for stopping water on the foundation until the pier is completed. In addition, the structure of the open caisson frame 10 of the present invention is applied.

That is, the conventional cast-in-place open caisson body 30 was lowered from the upper surface of the earth and sand in the cutoff wall 37 to a predetermined depth (the same depth as the length from the support layer to the upper end of the completed foundation). Later, the open caisson frame 10 composed of the PC blocks 12 is constructed so as to be sequentially stacked on the cast-in-place open caisson frame 30, and the cast-in-place open caisson frame 30 is lowered. The open caisson frame 10 composed of the PC blocks 12 is constructed until the lower end of the cast-in-place open caisson frame 30 reaches the support layer of the riverbed.

In FIG. 1, only the open caisson frame 10 of this embodiment constructed on the cast-in-place open caisson frame 30 is shown. In order to construct the open caisson frame 10 of this embodiment, first, at the production site of the PC blocks 12, the PC blocks 12 are manufactured.

In order to manufacture the PC blocks 12,..., A reinforcing bar is provided in the formwork, and the first and second connection members TU1, TU1,
The TU2 is arranged, and the left and right first and second connection members LR1, LR2 are arranged on the left and right connection surfaces 13, 13, respectively.

Then, the concrete blocks 12 are completed by pouring concrete into a mold and curing the concrete.
Next, the manufactured PC blocks 12 are transported to the construction site of the pier.
The weight and size of the open caisson frame 10 can be freely determined to some extent by changing the number of divisions of the open caisson frame 10 even when the open caisson frame 10 is large.

Accordingly, since the PC blocks 12 can be formed to have a weight and size that can be transported by the truck, the PC blocks 12 can be easily transported to the bridge pier construction site by the truck. .

Next, on the cast-in-place open caisson frame 30 formed as described above, the PC blocks 12 for one frame 11 are connected. At this time, the PC blocks 12 are arranged so that the first connecting member LR1 and the second connecting member LR2 face each other on the joining surfaces 13, 13 of the connected PC blocks 12. Each PC block 12 has a first connection member TU1 at the lower portion thereof, and a cast-in-place open caisson frame 3
0 so that it is located on the box emptying portion 31 on the upper surface.

In this embodiment, in order to widen the allowable range of the error in the shape of the PC blocks 12...
... is designed to have a gap at the connection part. Therefore,
The PC blocks 12 are arranged with a gap therebetween, and an error in the shape of the PC blocks 12 is absorbed by changing the interval between the adjacent PC blocks 12.

The cast-in-place open caisson frame 30
When the blocks 12 made of PC are arranged, concrete is thrown away. Then, in the cast-in-place open caisson frame 30 and the block 12 made of PC, an anchor bolt 32 is inserted into the box-opening portion 31 of the cast-in-place open caisson frame 30, and the anchor bolt 32 is connected to the first connection member TU1 with a nut. Fix using 34.

Then, the non-shrinkable mortar is filled in the box punching portion 31 to fix the cast-in-place open caisson frame 30 and the blocks 12 made of PC. And
The first connection member LR1 and the second connection member LR2, which are arranged to face each other on the joint surfaces of the adjacent PC blocks 12, 12, are fastened by bolts. At this time, the bolt 23 is inserted into the box-shaped member 20 from the bolt operation opening 22 of the first connection member LR1. Then, a washer 29 is inserted into the bolt 23. Next, bolt 23
Of the threaded portion of the first connecting member LR1
And the second connecting member LR2
Through the through hole of the flange portion 25, is inserted into the screw hole of the cylindrical portion 26, the screw portion of the bolt 23 is screwed to the cylindrical portion 26, the first connecting member LR1 and the second connecting member LR2 To conclude.

Since the left and right connecting members S are provided on both the outer peripheral side and the inner peripheral side, when the bending moment acts on the frame body 11, the connection surfaces 13, 13 serving as neutral shafts are provided.
Are joined at both sides of the central portion of the frame 11 so that bending stress can be reliably transmitted between the blocks 12 and 12 made of PC, and a force acting from the outside of the frame 11 is dispersed throughout the frame 11. Therefore, sufficient strength can be maintained even when the open caisson frame 10 is constructed from the PC blocks 12.

Next, the left and right adjacent PC blocks 12
... have a gap therebetween, and the left and right end surfaces (connection surfaces 13, 13) of the PC blocks 12 ...
Since the concave portions 15 are formed on the upper and lower sides, a grout material is cast in this portion.

The above operation is performed by a PC constituting one frame 11.
The frame 11 is completed by performing the processing between the blocks 12. As described above, the grout material is cast between the PC blocks 12...
1 is in a state where water is stopped.

Then, the cast-in-place open caisson frame 3
By further excavating the inside of the box 0, the frame 11 newly formed by the PC block 12 is lowered together with the cast-in-place open caisson frame 30. Next, the frame 11 is further constructed on the lowered frame 11.

In this case, not only are the PC blocks 12 constituting the frame 11 joined to the left and right as described above, but also the frame 11 formed earlier using the connecting members S for up and down. PC block 12 and frame 11 to be formed later
Are joined together. Further, in this case, the PC blocks 12 of the previously formed frame 11 are formed.
And the PC blocks 12 of the frame body 11 to be formed later are arranged so as to be staggered by being shifted by half the length of the PC blocks 12.

By arranging as described above, the joints of the PC blocks 12 are not aligned in a straight line with the upper and lower frames 11, so that the strength of the open caisson frame 10 composed of the PC blocks 12 is improved. Unevenness can be prevented, and the strength of the entire open caisson frame 10 can be improved.

Then, the lower side (the frame 11 formed earlier)
PC block 12: Second connection member TU2 on the top surface
And the PC block 12 on the upper side (the frame body 11 to be formed later)... On the lower surface of the first connection member TU1. Then, similarly to the case where the first connection member LR1 and the second connection member LR2 of the left and right connection members S are joined, the first connection member TU1 and the second connection member of the upper and lower connection members S are connected. TU2 is fastened by bolts 23.

As described above, the PC blocks 12.
The waterproof material 17 is disposed on the upper surface of the
Water leakage can be prevented between the blocks 12 made of C. Similarly, the PC blocks 12 adjacent to the left and right are joined to each other in the same manner as described above, so that a new frame 11 is formed on the frame 11 previously formed by the PC blocks 12.
Can be built.

Then, the frame 11 is lowered together with the cast-in-place open caisson frame 30 by excavating the inside of the cast-in-place open caisson frame 30 again. Then, by repeating the construction of the frame 11 and the settlement of the frame 11 as described above, as shown in FIG. 1, the open caisson frame 10 as a temporary water stop wall is completed.

Next, the cast-in-place open caisson frame 3
The cast-in-place open caisson skeleton 30 is used as the foundation of the pier by placing concrete, filling with gravel, etc. within 0. Then, the pier construction work is performed in the open caisson frame 10 composed of the PC blocks 12.

At this time, since the inside of the open caisson frame 10 is completely shut off by the connection of the upper, lower, left and right PC blocks 12,.. Water does not enter the open caisson frame 10.

The earth and sand in the sheet pile 36 and the sheet pile 36
Can be prevented from leaking into the open caisson frame 10. When the pier is completed, the open caisson skeleton 10 as the temporary water stop
To remove.

At this time, by removing the bolt 23, the open caisson frame 10 can be easily disassembled as compared with the integral cast-in-place open caisson frame, and the removal operation with a crane or the like can be facilitated. be able to. In addition, the removed open caisson frame 10
Can be reused if no decrease in strength due to removal work or the like is observed.
Can be diverted to other temporary water barriers and other uses,
It is also possible to reduce costs.

As described above, according to the structure of the open caisson frame 10 of this embodiment, the open caisson frame 1
By adopting a configuration including a plurality of blocks obtained by dividing 0 in the radial direction, even if the open caisson frame 10 is made of PC, it is possible to prevent the workability of transporting and constructing the open caisson frame 19 from decreasing.

The frame 1 is made up of the PC blocks 12.
1 is constructed and connected to the outer peripheral side and the inner peripheral side of the frame body 11 by connecting and connecting the connecting members S, thereby reliably transmitting the bending moment between the PC blocks 12 as described above. , And the strength of the open caisson frame 10 composed of the PC blocks 12 can be increased.

Further, even if the connecting member S which is composed of the first connecting members LR1 and TU1 and the second connecting members LR2 and TU2 and is fastened by the bolt 23 is used, the bolt operating opening 22 can be used. Is the first connection member LR1,
The second connection members LR2, TU2 are provided only for TU1.
Is not provided in the PC block 12.
..., the volume of the notched portion of the joint between them is reduced to make it easier to transmit a bending moment, particularly a compressive stress, and the extension of the first connecting members LR1, TU1 and the second connecting members LR2, TU2 With the extension member (rebar), the pull-out strength of the first and second connection members LR1, TU1, LR2, and TU2 can be increased, and a configuration in which a bending moment, particularly, a tensile stress can be easily transmitted can be achieved.

It goes without saying that a joint fitting other than the above-mentioned connecting member S may be used as the connecting member S of the PC block 12.

[0088]

As described above in detail, according to the structure of the open caisson frame according to the first aspect of the present invention, the open caisson is not constructed from a frame-shaped PC structure, but is constructed from a frame. Is constructed from PC blocks of a shape that is further divided into multiple parts, so that when building an open caisson frame with PC structures, there is no need to use special large trucks or special large cranes. Transportation and lifting work can be performed by a typical truck and crane.

Therefore, even in an area where transportation means and the like are restricted, such as an urban area, it is possible to perform work using a large open caisson made of PC, and not to use a special large heavy machine. Therefore, the cost can be reduced.

When the bridge pier is completed, the open caisson frame as the temporary water stop wall is removed. In this case, the open caisson frame is easily disassembled as compared with the integrated cast-in-place open caisson frame. Can be
Removal work with a crane or the like can be facilitated. In addition, the removed PC block of the open caisson skeleton can be reused if there is no decrease in strength due to removal work, etc., and it can be diverted to other temporary water stop walls and other uses. It is also possible to reduce the cost.

According to the method for constructing a pier according to claim 2,
The upper, lower, left and right P
Since the block made of C is completely stopped by the joining of the blocks made of C, water leakage from the earth and sand in the cutoff wall does not enter the open caisson body. Further, even if the earth and sand and the sheet pile in the cutoff wall are removed, water leakage into the open caisson body can be prevented.

According to the method for constructing a pier according to claim 3,
After lowering the conventional cast-in-place open caisson skeleton from the top of the earth and sand inside the cut-off wall to a predetermined depth, the open caisson skeleton consisting of the PC block was constructed to be sequentially stacked on the cast-in-place open caisson skeleton. As it moves, the cast-in-place open caisson structure is lowered, and an open caisson structure made of PC blocks can be constructed until the lower end of the cast-in-place open caisson structure reaches the support layer of the riverbed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an open caisson composed of a PC block inside a sheet pile for describing a structure of an open caisson frame of one embodiment of the present invention.

FIG. 2 is a sectional view showing the open caisson skeleton of the embodiment.

FIG. 3 is a development view of the open caisson skeleton of the embodiment.

FIG. 4 is a partially cutaway plan view showing the PC block.

FIG. 5 is a partially cutaway front view showing the PC block.

FIG. 6 is a side view showing the PC block.

FIG. 7 is a vertical sectional view showing the PC block.

FIG. 8 is an enlarged view of a portion indicated by D in FIG. 8 showing a water blocking material provided on the upper surface of the PC block.

FIG. 9 is a development view of a main part of the open caisson for explaining a connection position of the PC block.

FIG. 10 is a plan view showing up and down connecting members of the PC block of the embodiment.

FIG. 11 is a front view showing the upper and lower connecting members of the embodiment.

FIG. 12 is a side view showing the upper and lower connecting members of the embodiment.

FIG. 13 is a side view showing left and right connection members of the embodiment.

FIG. 14 is a front view showing left and right connection members of the embodiment.

FIG. 15 is a plan view showing a connection structure between the cast-in-place open caisson skeleton and the first connection member of the embodiment.

FIG. 16 is a front view showing a connection structure between the cast-in-place open caisson skeleton and the first connection member of the embodiment.

FIG. 17 is a side view showing a connection structure between the cast-in-place open caisson skeleton and the first connection member of the embodiment.

FIG. 18 is a perspective view showing an open caisson made of a PC structure according to the conventional example.

FIG. 19 is a cross-sectional view of a main part showing a connection structure between the conventional PC structures.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Open caisson frame 11 Frame 12 PC (precast concrete) block 13 Connecting surface 20 Box-shaped member 21 Reinforcing bar (extending member) 22 Opening 23 Bolt 26 Tube portion 27 Reinforcing bar (Extending member) S Connecting member LR1 First Connection member LR2 Second connection member TU1 First connection member TU2 Second connection member

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) E02D 23/00 E04B 2/02

Claims (3)

(57) [Claims] 1. A precast concrete block which is constructed in a tubular shape by connecting frames vertically to each other, and wherein each of the frames is formed by dividing the frame into a plurality of sections at a substantially vertical dividing surface. A method of constructing a pier using an open caisson skeleton formed by connecting in the direction as a temporary water blocking wall, wherein a cast-in-place open caisson skeleton as a foundation of the pier is constructed in a closing wall, and the above-described cast-in-place open caisson The open caisson frame consisting of the precast concrete blocks described above is constructed on top of the frame in such a way that it is sequentially stacked, and the cast-in-place open caisson frame is excavated, and the open caisson frame is settled down. An open caisson frame is used as the foundation for the pier, and is made of precast concrete blocks. A pier construction method characterized by performing pier construction work inside an open caisson body. 2. A method for constructing a pier according to claim 1, wherein a grout material is cast between adjacent left and right precast concrete blocks so that the inside of the frame is stopped. A method of constructing a pier, wherein a water-blocking material is disposed on an upper surface of a concrete block to prevent water leakage between upper and lower precast concrete blocks. 3. The method for constructing a pier according to claim 1 or 2, wherein the cut-off wall is filled with earth and sand, and the cast-in-place open caisson body serving as a foundation of the pier is constructed on the earth and sand. How to build a distinctive pier.