JPH05295709A - Bridge pier and its construction method - Google Patents

Abstract

(57) [Summary] [Purpose] There is no need to construct a double cut-off work or deep excavation, the number of steps required for construction is simplified, the construction period is shortened, and construction costs can be reduced, especially close to the existing piers. There is no risk of adversely affecting the existing piers even if
Provide (the structure of) the pier and its construction method. [Structure] A plurality of steel pipe piles 2 whose lower end reaches the support layer in the ground below the water bottom and whose upper end projects above the water surface, and those steel pipe piles 2 are surrounded, and a part of the steel pipe pile 2 is placed in the ground below the water bottom. A buried steel form 5 and a height that is arranged around the steel pipe pile 2 along the inner peripheral surface of the steel form 5 and that slightly exceeds the upper end of the steel pipe pile 2 from the lower end of the steel form 5 Reinforcement basket having a concrete part, a concrete part and a steel form frame 5 placed in a space in the steel form frame 5.
And a concrete portion 7 that extends upward along the outer peripheral surface of the steel pipe, and that integrates the upper end portion of the steel pipe pile 2 with the reinforcing bar cage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pier of a railway bridge or a road bridge and a construction method therefor, and more particularly to a pier and a construction method suitable for construction close to an existing pier (bridge). is there.

[0002]

2. Description of the Related Art For example, in the case of constructing a pier on a river, a pier has been conventionally installed on the river, and then cast-in-place piles are first constructed from this pier, and then a double cut-off work is performed to construct the pier frame. Install. Next, a general construction procedure is to excavate the earth and sand in the deadline to construct a pier frame and remove the deadline.

That is, the conventional construction method is shown in FIG.
And as shown in (b), a plurality of cast-in-place piles 31,
Construction will be carried out at a certain interval deep within the ground beneath the riverbed within the planned square footing construction position. Next, the steel sheet pile 32 is punched in a square shape with a certain interval from the planned outer shape of the footing construction, the steel sheet pile 33 is double-dried on the outer side thereof, and sand 36 is filled between the inner and outer steel sheet piles 32 and 33 to fill the inside. Prevent water from entering the steel sheet pile 32 (so-called double deadline construction). After extracting the water from the steel sheet pile (double deadline) 32, excavating the earth and sand, and constructing a footing 34 that integrally connects the upper portions of the cast-in-place piles 31 together with a reinforced concrete using a formwork, and further The pier frame 35 is continuously constructed above the pier frame 35 using reinforced concrete using a form (not shown). Then, after removing the formwork, the inner and outer steel sheet piles 32 and 33 are pulled out and removed. In addition, the code | symbol S in a figure is an existing bridge pier (bridge).

[0004]

However, the above-mentioned conventional method of constructing a bridge pier has room for improvement in the following points.

Since a construction method such as double cut-off work is required, the number of construction steps is large, each step work is complicated, and the construction period is long (about 4 months per pier). In the case of a river that has to be completed, it requires a lot of day and night work, which puts a heavy burden on the worker.

When the pier is constructed near the existing pier S (FIG. 6), the ground may be loosened during the construction of the double cofferdam (particularly at the time of removal), which may adversely affect the existing pier.

When the ground in the excavation or near the bottom of the excavation is soft, the ground is improved to suppress the displacement of the double cut-off work, or a chemical solution is injected below the bottom to stabilize the bottom of the excavation. Need to be done and the construction cost will be quite high.

The present invention has been made in view of the above-mentioned points, and it is not necessary to perform a double cut-off work or deep excavation, the construction process is simplified, the construction period is shortened, and the construction cost can be reduced. It is an object of the present invention to provide a pier (structure of pier) and a construction method therefor, which does not have an adverse effect on an existing pier even when it is constructed near the pier.

[0009]

In order to achieve the above-mentioned object, the pier of the present invention comprises: a) a plurality of steel pipe piles whose lower end reaches a supporting layer in the ground below the water bottom and whose upper end projects above the water surface. And b) a steel form frame that surrounds the steel pipe piles and is partially buried in the ground under the water bottom, and c) around the steel pipe piles along the inner peripheral surface of the steel form frame. With the rebar baskets distributed,
d) Concrete that extends upward along the outer peripheral surface of the steel form and the concrete part cast in the space inside the steel form, and integrates the upper end of the steel pipe pile with the rebar cage. And a section.

The construction method of the bridge pier according to the present invention is
1) Multiple steel pipe piles are constructed so that the lower end reaches the supporting layer in the ground below the water bottom and the upper end projects above the water surface.
A steel formwork that surrounds the constructed multiple steel pipe piles is hung from above the water surface with a crane or the like, and is sunk to a relatively shallow position in the ground below the bottom of the water with a certain distance from each steel pipe, Projecting the upper end of the steel formwork above the water surface,
3) After excavating the earth and sand in the steel formwork, pre-assembled rebar cages are suspended from above the water surface by a crane or the like and dropped around the steel pipe along the inner peripheral surface of the steel formwork, The upper end of the rebar cage is made to project slightly above the upper end of the steel pipe pile, and 4) a formwork is temporarily installed above the steel formwork so as to surround the rebar cage, and inside the temporary formwork and steel. After the concrete is cast in the formwork, the temporary formwork is removed.

In the construction method of the present invention, when a guide steel is projected in a vertical direction at an appropriate position on the inner surface of the steel form, and the steel form is built around a plurality of steel pipe piles. In addition, one of the H steels is inserted into the guide steel to maintain a constant gap between the steel pipe piles, and when the rebar cage is dropped into the steel form, the guide steel is attached to the rebar cage. It is preferable to insert and guide the tip of the CT steel.

[0012]

The pier of the present invention having the above construction (claim 1)
According to the construction method (Claim 2), a part of the steel pipe pile is projected above the water surface, and the periphery thereof is surrounded by a steel mold, and the steel mold part is projected above the water surface. ,
Since the lower end is sunk in the ground below the water bottom, it is possible to perform work such as excavating earth and sand in the steel form, and by dropping the rebar cage in the steel form and placing concrete. , The upper part of the steel pipe pile can be integrated. Therefore, there is no need for a double cut-off work to construct the pier frame, the work from excavation to concrete placement can be performed underwater, and there is no risk of loosening the ground.Construction should be performed near the existing pier. However, it does not adversely affect the existing piers. Furthermore, the auxiliary construction method for protecting the existing piers is not required, and the construction period and cost can be reduced.

Further, according to the construction method of claim 3, when the steel form is built around the plurality of steel pipe piles, the interval between the steel pipe piles is kept constant by the H steel. A space is secured when the rebar cage is dropped into the steel form and the steel pipe pile, and when the rebar basket is dropped, the rebar cage is guided by the guide steel and the CT steel along the inner peripheral surface of the steel form. It is possible to smoothly drop the rebar cage.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a bridge pier according to the present invention will be described below with reference to the drawings and a construction method thereof will be described.

FIG. 1 is a front sectional view showing a pier according to an embodiment of the present invention constructed near an existing pier. FIG. 2 is an enlarged cross-sectional view of the bridge pier of FIG. 1 taken along the line II-II and enlarged cross-sectional views of a portion A and a portion B in the enlarged cross-sectional view. FIG. 3 is a front view showing a lower portion of a steel pipe used for a steel pipe pile, an enlarged view of a portion C of the front view, and a sectional view taken along line D-D of the enlarged view. As shown in FIG. 1, the bridge pier 1 includes two steel pipe piles 2 that are sunk at regular intervals, a reinforced concrete pile 3 that extends downward from each of the steel pipe piles 2, and two steel pipe piles. The steel form 5 includes a steel form 5 surrounding the upper part of the steel pipe pile 2, and a concrete part 7 extending upward along the outer peripheral surface of the steel form 5. The pier 1 of the present embodiment is constructed close to the existing pier S.

Each of the steel pipe piles 2 has a lower end reaching a support layer in the ground below the river bottom (river bed) and an upper end protruding along the water surface along a long steel pipe 2a and an inner peripheral surface of the steel pipe 2a. It has a structure in which concrete 2c is cast in a steel pipe 2a. Around the lower end of the steel pipe 2a, as shown in FIG.
1 are formed at equal intervals in the circumferential direction, and hard facing processing is performed to increase the hardness of the cutting edge 2a-1. Therefore, the work of sinking (penetrating) the steel pipe 2a into the ground is easily performed.

The reinforced concrete pile 3 has a structure in which a lower end reaches a support layer in the ground and a reinforced cylinder which is assembled in a tubular shape by a reinforcing bar 3b continuous with the reinforcing bar 2b is integrated with concrete 3a. In the present embodiment, the construction cost is reduced by making the steel pipe pile 2 and the reinforced concrete pile 3 into a two-stage structure, but the steel pipe pile 2 may be extended to the portion of the reinforced concrete pile 3.

As shown in FIG. 2, the steel frame 5 has a substantially elliptical shape when viewed from above, and its surface is coated.
The lower end of the steel form 5 is buried in the ground below the riverbed, and the upper end projects above the water surface, but it is lower than the upper end of the steel pipe pile 2 so that the upper end of the steel pipe pile 2 is made of steel. 5 is projected above.

On the inner peripheral surface side of the steel form 5, a pair of L-shapes are provided at a total of 8 locations, that is, 4 locations on the arcuate portions corresponding to the left and right steel pipe piles 2 and 4 locations on the intermediate facing flat portions. Guide steel 5a formed by welding steel at intervals
Are projected in the height direction. Reinforcing cage 6 in steel form 5
The rebar cage 6 is assembled into a substantially elliptical shape slightly smaller than the steel form 5 using a large number of rebars, and its height is higher than that of the steel form 5. That is, the height is higher than the upper end of the steel pipe pile 2 protruding above the steel form frame 5. On the left and right of the middle portion of the rebar cage 6, the L-shaped steel frame member 6a is provided across the opposing cage members.
Guide steel 5a intermediate between the steel form 5 by welding through
A CT steel 6c having a T-shaped cross section is projected outward from the rebar cage 6 by welding at a position opposed to.

The earth and sand below the bottom of the river in the steel form 5 is excavated, the reinforcing bar cage 6 is inserted into the steel form 5, and then concrete is poured into the space inside the steel form 5. With
Steel pipe pile 2 in succession to this concrete part (not shown)
A concrete portion 7 that integrates the upper end portion of the steel sheet with the rebar cage 6 is extended upward along the outer peripheral surface of the steel form frame 5. The top portion 7a of the concrete portion 7 is formed to be slightly larger than the lower portion thereof by bulging outward over the entire circumference because a bridged shoe (not shown) is installed.

FIG. 4 is a schematic view showing the bar arrangement of the pier 1. As shown in the figure, the reinforcing bars inserted in the pier 1 are arranged in a cylindrical shape along the inner peripheral surface of the steel pipe 2a. , A reinforcing bar 2b continuous with the reinforcing bar in the lower reinforced concrete pile 3 and a reinforcing bar constituting the reinforcing bar cage 6. The upper end of the reinforcing bar 2b is the steel pipe 2a
It projects further and bends in a J shape, and the upper end of the reinforcing bar cage 6 reaches the top portion 7a of the concrete portion 7.

Next, the construction method of the pier 1 of the embodiment having the above-mentioned structure will be described in order.

First, as shown in FIG. 5, a temporary jetty 20 is installed from the bank to the construction position of the bridge pier 1 of the river. Reference numeral 21 in FIG. 5 is a pile for supporting the jetty 20, and a plurality of piles 21 are erected at regular intervals.

A predetermined length (21.20 in this embodiment)
m) steel pipe 2a to the crane 22 on the pier 20 (Fig. 5)
Suspend with, and drive into the ground below the river bottom to penetrate the support layer. The steel pipes 2a are arranged at regular intervals (4.
5 m) is opened and two pipes are placed along the river, and the upper portions of the steel pipes 2a are projected above the water surface as shown in FIG.

After excavating the earth and sand in each steel pipe 2a (below the riverbed), the earth and sand below each steel pipe 2a is excavated until it reaches the next support layer, and the reinforcing bars 2b are formed from inside each steel pipe 2a to the excavated portion below it. Are continuously arranged in a cylindrical shape at intervals, and the upper end of the reinforcing bar 2b is projected above the steel pipe 2a.

Concrete is placed in each steel pipe 2a and in the excavated portion below the steel pipe 2a to construct a foundation pile consisting of the steel pipe pile 2 and the reinforced concrete pile 3 continuous therebelow.

The steel formwork 5 is attached to the crane 2 on the pier 20.
It is suspended by 2 and surrounds two steel pipe piles 2, and it is sunk to a relatively shallow position in the ground below the river bottom at regular intervals with each steel pipe pile 2, and the upper end of the steel form 5 is above the water surface. To project. In this way, when building the steel form 5 around the steel pipe pile 2, one of the H steels 11 is inserted into the guide steel 5a as shown in FIG. While keeping at, slowly descend. The work of immersing the steel form 5 is not limited, but a water jet is installed in the steel form 5 and a vibro is installed on the upper part,
It is recommended to use the vibration of the vibro while cutting the ground below with a water jet.

After excavating the earth and sand in the steel form 5 (below the river bottom), the rebar cage 6 is suspended by the crane 22 on the pier 20 and two steel pipe piles are provided along the inner peripheral surface of the steel form 5. It is dropped so as to surround 2, and the upper end portion of the reinforcing rod cage 6 projects slightly above the upper end of the steel pipe pile 2. When the rebar cage 6 is dropped between the steel form 5 and the steel pipe pile 2, the CT steel 6
With the tip end of c inserted into the guide steel 5a, the guide steel 5a and the CT steel 6c guide and drop it so that the steel form 5 and the steel pipe pile 2 and the rebar cage 6 are kept constant. It is possible to secure the interval.

A form (not shown) such as a veneer plate is temporarily installed so as to surround the reinforcing bar cage 6 projecting upward along the steel form 5, and inside the temporary form and the steel form 5 Place concrete inside and remove the temporary formwork after the concrete has solidified. Finally, if the temporary pier 20 is removed, all the work is completed.

The pier 1 according to the embodiment of the present invention was constructed by the construction method comprising the above steps (1) to (3). According to this construction method, since the bridge pier 1 is mainly supported by the two steel pipe piles 2 and the footing that is indispensable for the conventional bridge piers is not required, the excavation depth is shallow, and the excavation work is made by the steel mold. Since it is carried out in the frame 5, the construction of double deadening work can be omitted and the auxiliary construction method for protecting the existing piers is no longer necessary. Therefore, the construction work is simplified, and even if the installation work of the temporary pier 20 etc. is included, the dry season (November to May)
The four piers were completed within the building, and the construction period was drastically shortened (about 1/2 of the conventional construction period) and the construction cost was reduced (about 1/2 of the conventional construction cost). In addition, it is not necessary to remove the double cofferdam, and it is not necessary to excavate deep into the ground, and since it is possible to perform underwater excavation, despite the construction close to the existing pier S (Fig. 1), It had no effect.

[0031]

As is clear from the above description,
The bridge pier and its construction method of the present invention have the following excellent effects.

(1) It is not necessary to construct a double cut-off work or deep excavation, the number of steps required for construction can be reduced, and the construction period can be shortened.

(2) Even when constructing a pier close to the existing pier, there is no need to construct a double deadline, and the ground will not be loosened when the pier is removed, which may adversely affect the existing pier. Since there is no need and no auxiliary construction method is required to protect the existing piers, construction costs can be reduced.

(3) The construction method according to claim 3 is the same as above.
In addition to the effects of (1) to (2), when building a steel form around a plurality of steel pipe piles, and when dropping the rebar cage between the steel form and the steel pipe pile, The steel form and the rebar cage can be smoothly inserted, and a constant space can be secured between the respective members.

[Brief description of drawings]

FIG. 1 is a front view cross-sectional view showing a pier according to an embodiment of the present invention constructed near an existing pier.

FIG. 2 is an enlarged cross-sectional view taken along line II-II of the bridge pier of FIG. 1 and enlarged cross-sectional views of a portion A and a portion B in the enlarged cross-sectional view.

FIG. 3 is a front view showing a lower portion of a steel pipe used for a steel pipe pile, an enlarged view of a C portion of the front view, and a sectional view taken along line D-D of the enlarged view.

FIG. 4 (a) is a schematic view of the reinforcement of the pier, where the left half shows the reinforcement in the steel pipe and the right half shows the reinforcement in the steel form and in the concrete part above it. FIG. 4B shows E of FIG. 4A.
4E is a sectional view taken along the line E, and FIG. 4C is a sectional view taken along the line FF in FIG.

FIG. 5 is a front cross-sectional view showing a working state in which a steel pipe is sunk.

FIG. 6 (a) is a front sectional view showing a pier by a conventional general construction method, and FIG. 6 (b) is a VI-of the pier of FIG. 6 (a).
FIG. 6 is a sectional view taken along line VI.

[Explanation of symbols]

 1 Pier 2 Steel pipe pile 3 Reinforced concrete pile 5 Steel formwork 5a Guide steel 6 Reinforcing cage 7 Concrete part

Front Page Continuation (72) Inventor Masayuki Yamamoto 2-4-24 Shibata Kita-ku, Osaka City, Osaka Prefecture West Japan Railway Company (72) Inventor Mitsuo Mori 2-4-2-4 Shibata, Kita-ku, Osaka City, Osaka Prefecture No. West Japan Railway Company (72) Inventor Tokio Tanaka 2-4-24 Shibata Kita-ku, Osaka City, Osaka Prefecture West Japan Railway Company (72) Inventor Yoshio Sugiyama Kita-ku, Osaka City, Osaka Prefecture 2-4-24 Shibata West Japan Railway Company (72) Inventor Shoichi Ueda 2-4-24 Shibata Shibata Kita-ku, Osaka City, Osaka Prefecture (72) Inventor Seichi Okamoto Within 5-21-20 Nishinakajima, Yonagawa-ku, Osaka-shi, Osaka Prefecture JR West Japan Consultants Co., Ltd. (72) Inventor Shuji Yajima 5-4-20 Nishinakajima, Yonagawa-ku, Osaka-shi, Osaka City JR West Japan Consultants Co., Ltd. ( 72) Inventor Shinho Mabe 9-18 Ikeda-cho, Nishinomiya-shi, Hyogo New Co., Ltd. In the group

Claims (3)

[Claims] 1. The lower end reaches a supporting layer in the ground below the bottom of the water,
A plurality of steel pipe piles with an upper end protruding above the water surface, a steel form frame that surrounds the circumference of these steel pipe piles and is partially embedded in the ground under the water bottom, and an inner peripheral surface of the steel form frame. Reinforcing bar baskets arranged around the steel pipe pile along, and extending upward along the outer peripheral surface of the concrete part and the steel form frame placed in the space part of the steel form frame, A pier comprising a concrete portion in which an upper end portion of a steel pipe pile is integrated with the rebar cage. 2. A plurality of steel pipe piles are constructed so that the lower end reaches a supporting layer in the ground below the water bottom and the upper end projects above the water surface, and surrounds the periphery of the constructed multiple steel pipe piles. The steel formwork is hung from above the water surface by a crane or the like, and is sunk to a relatively shallow position in the ground below the bottom of the water with a certain distance from each steel pipe, and the upper end of the steel formwork is projected above the water surface. Then, after excavating the earth and sand in the steel mold, pre-assembled rebar baskets are suspended from above the water surface by a crane or the like and dropped around the steel pipe along the inner peripheral surface of the steel mold, The upper end of the rebar cage is made to project slightly above the upper end of the steel pipe pile, and a formwork is temporarily installed along the steel formwork so as to surround the rebar cage, and inside the temporary formwork and the steel formwork. After placing concrete in the frame, remove the temporary formwork Method of constructing piers, characterized in that. 3. A guide steel projecting in a vertical direction at a proper position on the inner surface of the steel formwork, and when the steel formwork is built around a plurality of steel pipe piles, H is added to the guide steel. Insert one side of the steel to maintain a constant gap between each steel pipe pile, and when dropping the rebar cage into the steel form, insert the tip end of the CT steel attached to the rebar cage into the guide steel. The pier construction method according to claim 2, wherein the pier is inserted and guided.