JP5966442B2 - Pile head structure, pier structure using the same, and repair method thereof - Google Patents

Description

  The present invention relates to a pile head structure suitable for supporting a floor slab, a pier structure using the pile head structure, and a repair method thereof.

In general, as shown in FIG. 3, the pier has a structure in which a steel pipe pile 5 is driven on the sea 2 side of the revetment 1 and the floor slab 4 is supported by the steel pipe pile 5. In such a pier 3, when the floor slab 4 is greatly deformed in the horizontal direction due to a collision of a ship berthing or a large earthquake, the steel pipe pile 5 is buckled at the joint between the steel pipe pile 5 and the floor slab 4. Occur.
The steel pipe pile 5 that has buckled cannot sufficiently support horizontal forces (inertial force due to an earthquake or ship's berthing force), and the ship's berthing is hindered and the pier function is impaired. . Therefore, it is necessary to repair the steel pipe pile 5 that has been buckled. In particular, when a large-scale earthquake occurs, it takes approximately one week so that the ship for transporting relief supplies to the stricken area can berth. Immediate repair work that can be repaired in a short construction period is required. Therefore, when the steel pipe pile 5 of the existing pier 3 is buckled, various methods for repairing the steel pipe pile 5 have been studied.

For example, as shown in FIG. 4, a method of recovering the function of the buckling portion 9 by covering the outer surface of the buckling portion 9 of the steel pipe pile 5 below the floor slab 4 with reinforced concrete has been put into practical use. (See Non-Patent Document 1).
However, since all of the methods shown in FIG. 4 involve repair work under the floor slab 4 and work in seawater, workability is poor, and it is extremely difficult to perform repair work in a work period of about one week. difficult.

"Port Steel Structure Corrosion Prevention and Repair Manual (Revised)", Coastal Development Technology Center, April 1997, p187

  The present invention is a steel pipe pile head structure that can perform repair work for functional recovery in a short time and safely when buckling occurs in a steel pipe pile of a pier due to a collision of a ship berthing or a large-scale earthquake, etc. And a pier structure using the steel pipe pile head structure, and a repair method thereof.

  As a result of examining a technique for repairing a buckled steel pipe pile, the present inventor has constructed a pier having a structure in which the pile head is supported in advance by a steel pipe pile having a double pipe structure, and an earthquake or the like. After the steel pipe pile is buckled due to the above, the function is restored by filling the gap between the double pipes at the pile head with concrete or mortar, and the repair work is performed in a short time and safely. I got the knowledge that I can do it.

The present invention has been made based on such knowledge.
That is, the present invention is inserted inside the pile head of the steel pipe pile supporting the floor slab, and an inner steel pipe having a lower end below the lower surface of the floor slab, and concrete filled inside the inner steel pipe, A pile head structure comprising concrete filled in a portion embedded in the floor slab in a gap between the steel pipe pile and the inner steel pipe.

  In the pile head structure of the present invention, it is preferable to have at least two injection pipes that penetrate the floor slab from the upper surface of the floor slab to the lower surface of the floor slab in the gap between the steel pipe pile and the inner steel pipe. Moreover, it is preferable to have a slip prevention protrusion on the inner wall surface of the steel pipe pile and the outer wall surface of the inner steel pipe between the lower surface of the floor slab and the lower end of the inner steel pipe. Furthermore, it is preferable to have a bottom plate attached to the lower end of the inner steel pipe.

Moreover, this invention is a pier structure characterized by supporting a floor slab using said pile head structure.
Further, in the present invention, when buckling occurs at the pile head of the steel pipe pile in the above-mentioned pile head structure or pier structure, the gap between the steel pipe pile and the inner steel pipe is filled with concrete or mortar for repair. This is a repair method characterized by this.

  According to the present invention, when a buckling occurs in a steel pipe pile of a pier due to a collision of a ship berthing or a large earthquake, repair work for functional recovery can be performed safely in a short period of time. It will be possible to carry out the repair work of the pier advantageously, and there will be a remarkable industrial effect.

It is sectional drawing which shows typically the example of the jetty structure which supports a floor slab using the steel pipe pile head structure of this invention. It is sectional drawing which shows typically the example of repair after buckling arises in the steel pipe pile of FIG. It is sectional drawing which shows the principal part of a jetty structure typically. It is a side view which shows typically the example which repairs the conventional steel pipe pile. It is sectional drawing which shows typically the example which uses a bending rebar in the steel pipe pile head structure of this invention. It is sectional drawing which shows typically the example which installs a formwork in the steel pipe pile head structure of this invention.

FIG. 1 is a cross-sectional view schematically showing an example of a jetty structure that supports a floor slab using the steel pipe pile head structure of the present invention. With reference to FIG. 1, the pier structure using the steel pipe pile head structure of this invention is demonstrated below.
As shown in FIG. 1, an inner steel pipe 12 with a bottom plate 11 is installed on a pile head of a steel pipe pile 5 driven in a predetermined position. Here, the bottom plate 11 and the inner steel pipe may be fixed with a strength that does not come off even if concrete is put inside the inner steel pipe. As a method for fixing the position of the inner steel pipe 12, for example, there is a method of using a bent rebar 10 as shown in FIG.

Since the inner steel pipe 12 with the bottom plate 11 does not become an obstacle when installed inside the steel pipe pile 5, the diameter of the bottom plate 11 needs to be smaller than the inner diameter of the inner steel pipe 12. The gap generated thereby encloses a filler.
The width S of the gap between the steel pipe pile 5 and the inner steel pipe 12 is preferably in the range of 50 to 150 mm. If the gap width S is less than 50 mm, it will be difficult to inject concrete or mortar, which will be described later, and if the gap width S exceeds 150 mm, it will be difficult to transmit force via slippage prevention.

In addition, since the outer diameter and plate thickness of the steel pipe pile 5 can be obtained at low cost if the outer diameter is in the range of 600 to 1600 mm and the plate thickness is 9 to 25 mm, which are generally used pile dimensions. Economically advantageous.
The relationship between the thickness t ₅ (mm) of the steel pipe pile 5 and the thickness t ₁₂ (mm) of the inner steel pipe 12 is set so that the inner steel pipe 12 has a cross-sectional secondary moment equal to or greater than that of the steel pipe pile 5. After the buckling of the steel pipe pile 5 occurs, the load of the floor slab 4 can be supported by the inner steel pipe 12. The cross-sectional secondary moment I of the steel pipe is a value calculated by the following formula.
I = π {D ⁴ − (D−2t) ⁴ } / 64
Here, I is the cross-sectional secondary moment, D is the steel pipe outer diameter, and t is the steel pipe plate thickness.

Above the bottom plate 11 inside the inner steel pipe 12 whose lower end is blocked by the bottom plate 11, concrete 13 is filled in accordance with the concrete placement of the floor slab.
In addition, the gap between the steel pipe pile 5 and the inner steel pipe 12 on the upper side of the floor slab is also placed in the concrete of the floor slab by installing the formwork 14 shown in FIG. Fill with concrete to match.

The length L (mm) from the lower surface of the floor slab 4 to the bottom plate 11 is set to the same length as the diameter of the steel pipe pile as in a normal pier.
As shown in FIG. 1, the pier constructed by the above procedure has a hollow space between the steel pipe pile 5 and the inner steel pipe 12 below the lower surface of the floor slab 4.
Next, repair work for functional recovery after the buckling of the steel pipe pile 5 due to the collision of a ship berthing or a large-scale earthquake will be described with reference to FIG.

  As shown in FIG. 2, when repairing the buckled portion 9 of the steel pipe pile 5, concrete or mortar 15 is filled in the gap between the steel pipe pile 5 and the inner steel pipe 12 below the lower surface of the floor slab 4. Since the lower end of the gap between the steel pipe pile 5 and the inner steel pipe 12 is closed by the bottom plate 11, the concrete or mortar 15 does not fall to the bottom of the steel pipe pile 5. Since this filled concrete or mortar 15 adheres not only to the buckled portion 9 but also to the healthy steel pipe pile 5 and the inner steel pipe 12, the ship's berthing force acting on the floor slab and the inertial force in the event of an earthquake are applied to the inner steel pipe 12. Can be transmitted to the steel pipe pile 5 to restore the function.

In order to efficiently transmit the berthing force of the ship acting on the slab and the inertial force at the time of earthquake from the inner steel pipe 12 to the steel pipe pile 5, for example, the inner wall of the steel pipe pile 5 and the outer wall surface of the inner steel pipe 12 are prevented from slipping. A protrusion 16 can be provided. The slip stop may be cut, bent, and welded to the steel pipe pile in the same manner as that used to integrate the steel pipe pile and the floor slab part.
In filling concrete or mortar 15 into the gap in the gap between the steel pipe pile 5 and the inner steel pipe 12, for example, when the pier 3 is constructed in advance, the gap between the steel pipe pile 5 and the inner steel pipe 12 from the upper surface of the floor slab 4 is used. An injection tube 17 penetrating the floor slab 4 can be provided up to the lower surface of the floor slab 4. When steel pipe pile 5 is buckled due to the collision of a ship berthing or a large-scale earthquake, it is possible to work on floor slab 4 by filling concrete or mortar 15 from this injection pipe 17. Moreover, since it is not necessary to use heavy machinery, the repair work for the pier 3 can be carried out safely in a short period of time within one week.

If two or more injection pipes 17 are provided in one steel pipe pile 5, and one of them is used as an air vent, the concrete or mortar 15 can be filled smoothly.
As described above, the present invention includes an inner steel pipe that is inserted inside the pile head of a steel pipe pile that supports the floor slab, and a bottom plate that is attached to the lower end of the inner steel pipe and serves as a formwork when casting concrete. The steel pipe pile head structure has concrete filled inside the inner steel pipe above the bottom plate, and concrete filled in a portion embedded in the floor slab in the gap between the steel pipe pile and the inner steel pipe.

  In the steel pipe pile head structure of the present invention, from the upper surface of the floor slab to the lower surface of the floor slab in the gap between the steel pipe pile and the inner steel pipe, an injection pipe for filling concrete or mortar when the steel pipe pile buckles, It is preferred to have at least one air vent tube. In addition, a misalignment projection is installed on the inside of the steel pipe pile of the double pipe portion and on the outside of the internal steel pipe. After buckling occurs in the steel pipe pile of the pier, the gap part of the double pipe part is filled with concrete or mortar using an injection pipe, and the steel pipe pile and the inner steel pipe are integrated at the misalignment part to transmit the force. Thus, functional recovery before buckling is performed. Moreover, this invention is a jetty structure which supports a floor slab using some or all the above-mentioned steel pipe piles.

  In addition, the pile head structure of this invention is applicable to the foundation structure which has a steel pipe pile other than a pier structure. However, since it is easy to dive under the floor slab, buckling can be easily detected, but it is necessary to check by excavating the structure on the land.

Examples will be described using specific dimensions.
As shown in FIG. 1, an inner steel pipe 12 (outside diameter D ₁₂ : 800 mm, sheet thickness t ₁₂ ) with a bottom plate 11 on the pile head of a steel pipe pile 5 (outer diameter D ₅ : 1000 mm, sheet thickness t ₅ : 10 mm): 21mm). Thereby, a gap of 90 mm (= [D ₅ −2t ₅ −D ₁₂ ] / 2) on one side was provided between the steel pipe pile 5 and the inner steel pipe 12. On the inner wall surface of the steel pipe pile 5 and the outer wall surface of the inner steel pipe 12, the deviation preventing projections 16 are provided in advance in two rows in an annular shape over the entire circumference, and the inner steel pipe 12 is fixed inside the steel pipe pile 5. In this state, the displacement preventing projections 16 are arranged so as not to face each other. The length of the inner steel pipe was set so that the position of the fixed plate 11 was 1000 m from the floor slab 4 (that is, L = D ₅ ).

  Above the bottom plate 11 inside the inner steel pipe 12 whose lower end is blocked by the bottom plate 11, concrete 13 is filled in accordance with the concrete placement of the floor slab. In addition, the gap between the steel pipe pile 5 and the inner steel pipe 12 on the upper side of the floor slab is also placed in the concrete of the floor slab by installing the formwork 14 shown in FIG. Fill with concrete to match.

When the pier 3 was constructed in advance, two injection pipes 17 penetrating the floor slab 4 were installed from the upper surface of the floor slab 4 to the lower surface of the floor slab 4 in the gap between the steel pipe pile 5 and the inner steel pipe 12.
When steel pipe pile 5 is buckled due to the collision of a ship berthing or a large-scale earthquake, it is possible to work on floor slab 4 by filling concrete or mortar 15 from this injection pipe 17. Moreover, since it is not necessary to use heavy machinery, the repair work for the pier 3 can be carried out safely in a short period of time within one week.

  In addition, it is necessary to cover the upper part of the injection tube normally so that rainwater or the like does not enter.

DESCRIPTION OF SYMBOLS 1 Revetment 2 Sea 3 Pier 4 Floor slab 5 Steel pipe pile 6 Reinforced concrete 7 Reinforced steel plate 8 Slit 9 Buckling part
10 Bending bar
11 Bottom plate
12 inner steel pipe
13 Concrete
14 Formwork
15 Concrete or mortar
16 Misalignment protrusion
17 Injection tube

Claims (5)

Inserted inside the pile head of the steel pipe pile supporting the floor slab and having a lower end below the lower surface of the floor slab, concrete filled inside the inner steel pipe, the steel pipe pile and the Concrete filled in a portion of the gap between the inner steel pipe and the floor slab, and from the upper surface of the floor slab to the lower surface of the floor slab in the gap between the steel pipe pile and the inner steel pipe, A pile head structure having at least two injection pipes penetrating the floor slab . 2. The pile head structure according to claim 1, wherein the pile head structure has a displacement preventing protrusion on an inner wall surface of the steel pipe pile and an outer wall surface of the inner steel pipe between a lower surface of the floor slab and a lower end of the inner steel pipe. Pile structure according to claim 1 or 2, characterized in that it has a bottom plate attached to the lower end of the inner steel tube. A pier structure using a pile head structure according to any one of claims 1 to 3 to support a floor slab. In the pile head structure according to claims 1 to 3 or the pier structure according to claim 4 , when buckling occurs at the pile head of the steel pipe pile, concrete or mortar is formed in a gap between the steel pipe pile and the inner steel pipe. A repair method characterized by filling and repairing.

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