JPH01235713A - Earthquake-proof reinforcement construction of caisson structure - Google Patents

Abstract

PURPOSE:To prevent the outflow of a caisson fill by passing through holes bored in a caisson basement with casing pipes and piercing the insides of casing pipes with earthquake-proof reinforcing piles. CONSTITUTION:Casing pipes 6 are passes through holes 2a bored in a caisson basement 2 to link the inside of a caisson 1 with the ground under a mound. Earthquake-proof reinforcing piles 4 are passes through the insides of the casing pipes 6, and the force of fill absorption between a caisson fill section and the mound section under the caisson basement 2 is not generated. Accordingly, the outflow of the caisson fill 3 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an earthquake-resistant reinforcement structure for a caisson structure such as a gravity concrete caisson.

[Prior art and problems to be solved] As one method for seismically reinforcing caisson structures, as shown in Fig. 16, piles 4 for seismic reinforcement are penetrated through the caisson bottom slab 2 and embedded into the supporting ground. There is a construction method to do so. This construction method involves making a large number of small holes 5 in a part of the seismic reinforcement pile 4,
The aim is to prevent liquefaction of ground that has the potential for liquefaction. However, in order to drill into the caisson bottom plate 2 and erect the resistor 4, some kind of treatment must be taken at the drilled portion.

That is, the caisson filling material 3 may flow out from the gap between the shaft 4 and the hole 2a of the caisson bottom plate 2, and the stability of the caisson I, which is a gravity structure, may not be maintained.

For this reason, a method has conventionally been proposed in which a ring 20 and mortar 21 are used to prevent the caisson filling material 3 from flowing out, as shown in FIG. However, with this method alone, if the pile 4 is largely displaced near the caisson bottom plate 2, a gap will be created between the shaft 4 and the mortar 21, and the suction action of water from inside the caisson 1 toward the mount 9 will cause the caisson to become clogged. Material 3 may leak out.

The earthquake-resistant structure of the caisson structure of this invention prevents the caisson filling material from being sucked out between the inside of the caisson and the mount by using a casing pipe installed to connect the caisson bottom plate and the ground below the mount, thereby solving the above problems. This is an attempt to solve the problem.

[Means to solve the problem]

An overview of the invention will be explained below with reference to FIG.

In this invention, a casing pipe 6 having an inner diameter larger than the outer diameter of the seismic reinforcement pile 4 that penetrates the caisson bottom plate 2 and is erected to good ground is installed so as to connect the ground below the caisson bottom plate 2 and the rubble mount 9, The seismic reinforcement pile 4 is passed through the casing pipe 6, and the caisson filling material 3 is inserted into the casing pipe 6.
We are trying to prevent the outflow of

The casing pipe 6 only needs to penetrate into the ground below the mount 9 by a length necessary to prevent the caisson filling material 3 from flowing out. The casing pipe 6 has a flange portion 7 having a diameter larger than the diameter of the hole 2a bored in the caisson bottom plate 2 attached to its upper part, so that the lower surface of the flange portion 7 is brought into contact with the upper surface of the caisson bottom plate 2. , the casing pipe 6 can be locked to the caisson bottom plate 2.

The seismic reinforcing pile 4 used in this invention has the side surface of JP-A-61-146910 or JP-A-62.
A steel pipe pile having a large number of small holes 5 for water passage as seen in Japanese Patent No. 211416 can be used. In other words, the excess pore water pressure generated in the sandy ground during an earthquake is absorbed by the small hole 5.
By dissipating more water into the steel pipe shaft, liquefaction of the sandy ground can be prevented, resulting in effective seismic reinforcement. In addition, depending on the ground conditions, a synthetic resin pipe with a perforated part, or a pile without a perforated part may be used if liquefaction is not a problem.

〔Example〕

Next, the illustrated embodiment will be explained along with its construction procedure.

First, as shown in Fig. 2, a conventionally used normal casing pipe 12 is installed in the filling part of the caisson l that is to be seismically reinforced, and the filling material 3, etc. inside the casing pipe 12 is discharged. . Then, an excavator is inserted into the casing pipe 12, and the caisson bottom plate 2 and the rubble mount 9 are bored. Hole 2a of caisson bottom plate 2 and mount 9
The diameter of the hole in this section is larger than the outer diameter of the seismic reinforcement pile 4 that will later be erected through the inside of the caisson 1 to the supporting ground below the mount 9. (See Figure 3).

Next, as shown in FIG. 4, a casing pipe 6 having a diameter smaller than the diameter of the hole in the caisson bottom plate 2 and the rubble mount 9 is inserted into the hole. The method for inserting the casing pipe 6 into the perforation of the rubble mount 9 is as follows:
If the hole does not stand up on its own until the casing pipe 6 is inserted after drilling, a method may be adopted in which the casing pipe 6 is inserted into the hole while drilling the rubble mount 9. The tip of the casing pipe 6 is fixed in the ground below the mount 9. At the top of the casing pipe 6,
As shown in FIGS. 5 to 7, a flange portion 7 having a diameter larger than the hole 2a drilled in the caisson bottom plate 2, for example, a circular plate having a diameter smaller than the diameter of the casing pipe 12 installed in the filling part of the caisson 1, is used. Install it. This casing pipe 6 is installed so that the lower surface of the flange portion 7 and the upper surface of the caisson bottom plate 2 are in close contact with each other to prevent the caisson filling material 3 from flowing out. The casing pipe 6 is preferably made of steel, but may be made of synthetic resin, concrete, or any material comparable to these.

As shown in FIG. 8, a stretchable backing 13 (for example, a rubber backing) is provided in the gap between the upper part of the casing pipe 6 and the hole 2a of the caisson bottom plate 2 to prevent the filling material 3 from flowing out. can do. FIG. 9 shows a case where the backing 14 wraps around between the lower surface of the flange part of the casing pipe 6 and the upper surface of the caisson bottom plate 2, and the backing 15 is also placed inside the casing pipe 6 as shown by the two-dot chain line in FIG. It is also possible to close the gap between the inner surface of the casing vibe 6 and the seismic reinforcement pile 4.

After installing the casing pipe 6 to connect the ground below the caisson bottom plate 2 and the mount 2, as shown in FIG.
2 and the casing pipe 6 installed in the caisson bottom plate 2 part to penetrate to a predetermined stratum. Earthquake reinforcement pile 4
is preferably made of steel, but may also be made of synthetic resin, concrete, or a composite material combining steel, synthetic resin, concrete, etc. When a perforated portion with a large number of small holes 5 is provided in the shaft 4, the perforated portion is located in a stratum where liquefaction may occur (sand layer 8 below the mount 9). If the seismic reinforcement pile 4 is not required due to ground conditions, it may be a pile without a perforated portion.

After the earthquake reinforcement pile 4 is erected, sand 16 is poured into the gap between the casing pipe 12 and the pile as shown in FIG. The casing pipe 12 is pulled out while sand 16 is being introduced. It is desirable to put the sand 16 in such a way that it fills the gap between the casing pipe 6 and the seismic reinforcement pile 4, but if the gap is small, it is also possible to wait for the sand 16 to fill naturally.

In this case, the inside of the caisson l and the ground below the mount 9 communicate through the gap between the casing pipe 6 and the seismic reinforcement pile 4, but there is no suction between them like inside the mount 9. By embedding the casing pipe 6 into the ground below the mount 9, the caisson filling material 3 is prevented from flowing out (FIG. 11). The above-mentioned FIG. 1 shows the situation in which the casing pipe 6 has been removed and the inside of the caisson 1 has been filled with sand 16.

In order to prevent the caisson filling material 3 from flowing out, a filling material 17 such as mortar or mastic may be placed near the caisson bottom plate 2 as shown in FIG. 12. This filling material 17
Fill the gap between the casing pipe 6 and the seismic reinforcement pile 4 as much as possible, and fill the caisson bottom plate 2 to about the thickness of the caisson bottom plate 2. When injecting mortar as the filler 17, dowels 18, reinforcing bars, etc. may be attached to the flange portion 7 of the casing pipe 6 and the seismic reinforcement pile 4 to achieve integration. In FIG. 13, a cylindrical tube 19 is temporarily fixed to the lower end of the casing pipe 12 installed in the caisson 1, and the cylindrical tube 19 is filled with a filler 17. This cylindrical pipe 19 facilitates the removal of the casing pipe 12 and is left behind even after removal.

As another shape of the casing pipe 6, as shown in FIG.
Like the casing pipe 6 shown in the figure, it may be installed between the caisson bottom plate 2 and the ground below the mount 9. In this case, after the casing pipe 6 is installed, the gap between the casing pipe 12 in the caisson 1 and the seismic reinforcement pile 4 may be filled with only sand, or a filler 17 such as mortar may be filled as shown in FIG. However, it may also be structured to prevent the caisson filling material 3 from flowing out. Further, as shown in the figure, a dowel 18 or the like may be attached to the casing pipe 6, or a cylindrical pipe may be used as in the case of Fig. 13.

〔Effect of the invention〕

In this invention, the casing pipe is passed through a hole drilled in the caisson bottom plate and installed to connect the inside of the caisson with the ground below the mount, and the seismic reinforcement pile is passed through the inside of the casing pipe. The generation of suction force for filling material between the filling part and the lower mount part of the caisson bottom plate is eliminated. In this way, by reliably preventing the caisson filling material from flowing out, the caisson structure can be stabilized, and seismic reinforcement work can be performed easily and at low cost.

Furthermore, since the structure has seismic reinforcement piles passed through a casing pipe that penetrates through holes in the caisson bottom slab, it is possible to flexibly cope with the displacement of seismic reinforcement piles due to earthquakes or other causes.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing the overall structure of an embodiment of the present invention, Figs. 3 is an enlarged sectional view of the main part, Fig. 4 is a vertical sectional view showing how the casing pipe is inserted, Fig. 5 is an enlarged sectional view of the main part, and Fig. 6 is an enlarged sectional view of the casing pipe. A perspective view showing an example, Fig. 7 is a horizontal sectional view showing how the casing pipe is installed, Figs. 8 and 9 are vertical sectional views of the casing pipe section when backing is used, and Fig. 1O is seismic reinforcement. FIG. 11 is an enlarged sectional view of the main parts; FIGS. 12 and 13 are vertical sectional views showing an example of how to fill the upper part of the casing pipe; FIG. 14 is a vertical sectional view showing how the pile is driven. 15 is a perspective view showing a modified example of the casing pipe, FIG. 15 is a vertical sectional view when the casing pipe of FIG. 14 is used, and FIGS. 16 and 17 are
The figure is a vertical sectional view of a conventional example. 1... Caisson, 2... Bottom plate, 2a... Hole, 3...
...filling material, 4...earthquake reinforcement pile, 5...small hole, 6.
...Casing pipe, 7...Flange part, 8...
Sand layer, 9... Rubble mount, 10... Backfill material, 11
...Back filling soil, 12...Casing pipe, 13,1
4.15...backing, 16...sand, 17...
filler, 18... dowel, 19... cylindrical tube, 20.
...Ring, 21...Mortar Fig. 5 Fig. 9 Fig. 10 Fig. 14 Fig. 13 Fig. I) Reactor power Fig. 11

Claims (3)

[Claims] (1) A caisson is installed on the mount, and a hole is drilled in the caisson bottom plate of the caisson structure, which is made by filling the inside with filler material, and the seismic reinforcement pile is penetrated through the hole and rooted to the supporting ground. In the seismic reinforcement structure of a caisson structure, the casing pipe having an inner diameter larger than the outer diameter of the pile is passed through the hole drilled in the caisson bottom plate to connect the inside of the caisson and the ground below the mount. A seismic reinforcement structure for a caisson structure, characterized in that the seismic reinforcement piles are installed so as to penetrate through the inside of the casing pipe. (2) Earthquake resistance of the caisson structure according to claim 1, wherein the casing pipe has a flange portion at an upper portion thereof, and the lower surface of the flange portion is brought into contact with the upper surface of the caisson bottom plate and is latched to the caisson bottom plate. Reinforced structure. (3) The seismic reinforcement structure for a caisson structure according to claim 1, wherein the pile is made of a steel pipe or a synthetic resin pipe having a large number of small holes in a part of the side surface.