JP2001164583A - Seismic isolation method for underground structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide seismic isolation for an underground structure by utilizing a retaining wall. SOLUTION: An earth retaining wall B with cast-in-place steel pipe pile columns is constructed at a position far from a predetermined distance from an expected location of an underground structure A is constructed. And the ground C surrounded by a retaining wall B is excavated, and an underground structure A is constructed on the ground C while separating it from the retaining wall B. In this way, the construction ground site C surrounded by the retaining wall B is protected from the ground deformation and phenomena of liquefaction due to an earthquake or the like in the nearby ground by the retaining wall. And its stabilization is maintained and the concentration of seismic load to the underground structure can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation system for a structure in which the influence of an earthquake on an underground structure is suppressed by utilizing a steel pipe column retaining wall provided for the construction of an underground structure. It is about the law.

[0002]

2. Description of the Related Art When constructing underground structures such as railways, roads and buildings, earth retaining walls are installed on the ground surrounding the structures. Most of the retaining walls are temporary structures, and after the completion of the underground structure, they have completed their role. However, because they are difficult to pull out and remove, they are generally left underground.

[0003] In the design of underground structures,
The required cross-sectional thickness and the like have been determined assuming that only the structure exists in the ground, ignoring the existence of the remaining earth retaining wall. However, in practice, a retaining wall is left outside of the underground structure, which is expected to be effective in suppressing ground deformation and fluidization around the underground structure during an earthquake. There has been proposed a method of improving the seismic resistance of an underground structure by integrating the underground structure with the underground structure and making the underground structure slimmer. (JP-A-4-155018
JP, JP-B 8-9867)

[0004]

However, in the methods according to these proposals, in order to integrally connect the earth retaining wall and the underground structure, for example, a cross section which is a connecting point between the lower end of the underground structure and the earth retaining wall is used. In some cases, the seismic load was concentrated on the changing part, and reinforcement such as making the cross section larger was necessary, and the construction was troublesome.

The present invention has been made in order to solve the above-mentioned problems. The present invention utilizes the function of suppressing the deformation of the ground around the underground structure by the constructed retaining wall, and makes the ground surrounded by the retaining wall, The underground structure is constructed separately from the retaining wall, thereby preventing seismic loads from concentrating on the section where the cross section changes and improving seismic isolation on the underground structure. The aim is to provide a construction method that can contribute to the slimming of underground structures (reduction of construction cost and construction period).

[0006]

The construction of the present invention for achieving the above object will be described with reference to the accompanying drawings. The construction method of claim 1 relates to the construction of an underground structure A. A steel pipe column soil retaining wall B is installed at a predetermined distance from the planned position, and the soil retaining wall B and the separated portion 2 are not integrated with the soil retaining wall B in the ground area surrounded by the soil retaining wall B. To construct the underground structure A.

According to the construction method of the second aspect, when constructing the underground structure A, the steel pipe column soil retaining wall B is provided at a position away from the planned construction position by a predetermined distance, and the opposed soil retaining wall B is provided.
Are connected by a beam member 7, and in the ground area surrounded by the retaining wall B, the underground structure A is constructed without the integration with the retaining wall B but with the separated portion 2 existing. It is.

[0008] The construction method of claim 3 is characterized in that, in the construction method of claim 1 or 2, earth and sand 4 are backfilled in the separated portion 2.

The construction method according to claim 4 is the construction method according to claim 1 or 2, wherein the seismic isolation material 6 is interposed in the separated portion 2 and the seismic isolation material 6 is connected between the earth retaining wall B and the underground structure A. It is characterized in that it is joined through the intermediary.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show embodiments of the first method, and FIGS. 4 to 6 show embodiments of the second method.

First, an embodiment of the first method will be described. In FIG. 1, A is an underground structure to be constructed (including an underground structure portion of a building), and B is a steel pipe column retaining wall (hereinafter referred to as a retaining wall) provided on the ground surrounding the structure when constructing the underground structure A. Wall). This retaining wall B
As is well known in the art, a steel pipe sheet pile 1 formed by providing joints on opposite outer surfaces of a steel pipe is used. It is inserted and installed. This method is called a so-called ONS method.

In the construction method of the present invention, the retaining wall B is provided at a position away from the planned construction position of the underground structure A by a predetermined distance. As a result, the unification of the underground structure A and the retaining wall B is eliminated, and the seismic load is prevented from being concentrated on the cross-section change portion or the like due to the connection of the two A and B, and the two A and B are combined. Try to reduce mutual interference during an earthquake.

After the installation of the earth retaining wall B, the construction ground C between the earth retaining walls B, B is excavated to a predetermined depth point a to remove the earth and sand, and then the underground structure A is moved to a predetermined level on the ground C. The position, that is, the underground structure A is constructed at a position separated from the retaining wall B by a predetermined distance L. As a result, a required separation portion 2 is formed between the outer periphery of the underground structure A and the retaining wall B.

In the above-mentioned construction, the steel pipe sheet piles 1 and 1 are usually not lifted up on the retaining wall B exposed by the excavation of the construction ground C, and the material 3 is not removed and is used as a reinforcing beam of the retaining wall B as it is. It is good to utilize. In addition, it is advisable to strengthen the earth retaining wall B by newly providing a reinforcing beam 3 for connecting the steel pipe sheet piles 1 and 1 to the earth retaining wall B in which the bulging material 3 is not provided.

After completion of the underground structure A, the space 2 between the underground structure A and the retaining wall B can be used in various ways as an incidental cavity of the structure A. In this case, it is preferable to place a lid (for example, grating or the like) 4 for closing the surface portion of the separated portion 2 to cover the same.

According to the above construction method, since the construction ground C on which the underground structure A is constructed is surrounded by the retaining wall B, the retaining wall B resists the deformation of the ground due to the occurrence of the earthquake. , Will suppress the ground deformation,
A large seismic isolation effect on the underground structure A is achieved. Further, since the underground structure A and the retaining wall B are separated from each other, they are less likely to interfere with each other.
Since B is not integrally connected, there is no load concentration on the cross-section change portion or the like during an earthquake. Therefore, as a result, seismic isolation and seismic resistance are improved, which can contribute to slimming of underground structures (reduction of construction cost, shortening of construction period, etc.).

FIG. 2 shows another embodiment of the first method. In this example, the separated portion 2 between the underground structure A and the retaining wall B is not simply a hollow portion, but the sediment 5 is buried in the separated portion 2. According to this example, the separation portion 2
Can be used on the site. Further, the retaining wall B and the underground structure A are in contact with each other only through the earth and sand 5, and both
Since they are not integrated, there is no load concentration during an earthquake, so seismic isolation and anti-seismic effects can be fully expected.

FIG. 3 shows still another embodiment of the first method. In this example, underground structure A
A seismic isolation member 6 is interposed in the space 2 between the lands and the retaining wall B. As the seismic isolation material 6, for example, an elastic material such as asphalt, urethane, silicon, liquid rubber, and solid rubber is used. The seismic isolation material 6 may be filled in the entire gap 2 as shown in the figure, or may be provided partially at a required location. In this case,
Since the retaining wall B and the underground structure A are joined via the seismic isolation material 6, the attenuation and absorption of seismic waves can be effectively performed, and the influence of the earthquake on the underground structure is reduced. Is done.

Next, an embodiment of the second method will be described. In this construction method, as shown in FIGS. 4 to 6, the retaining walls B facing each other across the underground structure A are connected to each other by, for example, a beam member 7 such as bottom concrete at upper and lower intermediate portions thereof. The underground structure A is constructed on the beam member 7. In this case, although not shown, earth and sand are once back-filled on the beam member 7 by a required thickness, and the underground structure A is constructed on the earth and sand, or the beam member 7 and the underground structure A It is good to interpose a seismic isolation material such as a cushion body between them. In the second construction method, as in the first construction method, the separated portion 2 is formed between the retaining wall B and the underground structure A.

For connecting the retaining wall B and the beam member 7, various conventionally known means can be adopted. For example, when the beam member 7 is formed of concrete, as shown in the drawing, a reinforcing bar stud 8 is protruded from the outer surface of the steel pipe sheet pile 1 and is buried in the concrete. In addition, there is a method in which a plate or a bracket is protruded from the steel sheet pile 1 and connected to the beam member 7.

In this method, the opposed retaining walls B, B are connected to each other by the beam member 7, so that the retaining walls B, B can be strengthened, and cooperate with the fluctuation of the ground to cope with the fluctuation of the ground. The effect of suppressing fluctuations and fluidization will be promoted, and the horizontal restraining force of the ground immediately below the underground structure will increase, which will improve the vertical support force of the construction ground C due to the arch effect. Become.

FIG. 4 shows an example in which the space 2 between the retaining wall B and the underground structure A is used as an incidental cavity.
The configuration is the same as that in the example of FIG. In the example of FIG. 5, the separated portion 2 is filled with earth and sand 5, which is the same as in the example of FIG. In the example of FIG. 6, the seismic isolation member 6 is interposed in the separated portion 2 as in the example of FIG. 3.

In the method of the present invention, although not shown in the drawing to further strengthen the retaining wall B itself, the steel pipe of the steel pipe sheet pile 1 constituting the retaining wall B is made thicker than necessary for the stability calculation of the retaining wall. It can also be reinforced by inserting an H-beam into the steel pipe.

[0024]

As described above, according to the present invention,
When constructing an underground structure, a steel pipe column retaining wall will be installed at a location far away from the planned construction location, and the underground structure will be constructed separately from the retaining wall without being integrated with the retaining wall As a result, it is possible to suppress the deformation of the ground due to earthquakes, etc., and reduce the effect on the ground where the underground structure was constructed by the steel pipe column retaining wall with excellent workability, proof strength, and water shielding. Seismic isolation of ground and underground structures,
Stabilization can be achieved.

Since the underground structure is constructed on the ground surrounded by the retaining wall without being joined to the retaining wall, the underground structure is less affected by deformation or liquefaction of the surrounding ground, Moreover, the concentration of the seismic load due to the integration with the retaining wall is prevented as in the related art. Therefore,
As a result, the underground structure can be made slim, the construction cost can be reduced, and the construction period can be shortened.

According to the construction method of claim 2, since the retaining walls are connected to each other by the beam members and integrated, the overall structure of the retaining walls can be strengthened, and each retaining wall cooperates with the deformation of the surrounding ground. A larger restraining function is exhibited, and the horizontal restraining force of the ground below the beam member is increased, so that the vertical supporting force is improved by the arch effect.

In particular, according to the construction method of claim 3, in addition to the above-mentioned effects, land use can be made at a distance from the earth retaining wall to the underground structure. Because they are in contact with each other via the seismic isolation material, the seismic isolation effect can be obtained without taking a large space, and the area of the earth retaining wall facility, that is, the construction site can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a first construction method.

FIG. 2 is a longitudinal sectional view showing another embodiment.

FIG. 3 is a longitudinal sectional view showing still another embodiment.

FIG. 4 is a longitudinal sectional view showing one embodiment of a second method.

FIG. 5 is a longitudinal sectional view showing another embodiment.

FIG. 6 is a longitudinal sectional view showing still another embodiment.

[Explanation of symbols]

 Reference Signs List A Underground structure B Steel pipe column retaining wall C Construction ground 1 Steel pipe sheet pile 2 Separated part 5 Sediment 6 Seismic isolation material 7 Beam member

Claims (4)

[Claims] When constructing an underground structure, a steel pipe column retaining wall is provided at a predetermined distance from a planned construction position, and integrated with the retaining wall in a ground area surrounded by the retaining wall. A method of seismic isolation of an underground structure, characterized by building an underground structure with an earth retaining wall and a gap. 2. In constructing an underground structure, a steel pipe column retaining wall is provided at a position separated by a predetermined distance from a planned construction position, and the opposed retaining walls are joined by a beam member and surrounded by the retaining wall. A method of seismic isolation of an underground structure, characterized in that an underground structure is built in a separated ground area without being integrated with the earth retaining wall, but with a gap. 3. The seismic isolation method for an underground structure according to claim 1, wherein earth and sand are backfilled in the separated portion. 4. The underground structure according to claim 1, wherein a seismic isolation material is interposed in the separated portion, and the retaining wall and the underground structure are joined via the seismic isolation material. Seismic method.