JP2009155794A - Base isolation construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base isolation construction method, effective and suitable for achieving the base isolation of an existing building. <P>SOLUTION: This base isolation construction method includes: a process of constructing an earth retaining wall 10 along an existing building 1 as a base-isolation object in the periphery thereof; a process of constructing a base isolation pit 2 in the periphery of the underground part of the existing building and below it while restraining the horizontal displacement of the existing building by a horizontal displacement restraining means 12 installed between the earth retaining wall and the existing building; a process of disposing a reinforcement mat 3 for directly reinforcing the existing foundation by work in the base isolation pit and driving a pile 13 into the lower ground of the base isolation pit to temporarily support the existing building through the reinforcement mat; and a process of disposing a batholith as a new foundation at the bottom in the base isolation pit, interposing a base isolation device between the batholith and the reinforcement mat, and then releasing temporary support of the pile to support the existing building through the reinforcement mat using the base isolation device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for isolating existing buildings.

As a so-called seismic isolation retrofit method for isolating an existing building, for example, the one disclosed in Patent Document 1 has been proposed.
This is intended for existing buildings with solid foundations, and the foundations under the existing buildings are excavated to construct pile bodies by the deep foundation method, and the existing buildings are installed with support interposed between the pile bodies and the solid foundations. The seismic isolation pit is constructed in a state where it is temporarily supported, and a bottom base is newly installed at the bottom of the base isolation pit, and a base isolation device is interposed between the bottom base and the existing solid foundation.
JP 2003-253911 A

  The conventional seismic isolation method described above is considered to be effective as a seismic isolation method for existing buildings with a relatively small and simple structure. Therefore, it is not possible to secure seismic isolation while using existing buildings, so it is desirable to develop a more effective and appropriate seismic isolation method.

  The present invention is a seismic isolation method for an existing building whose foundation structure is directly based, and constructs a mountain wall surrounding the existing building along the periphery of the existing building to be seismically isolated The ground between the existing building and the mountain wall is directly grounded while restraining the horizontal displacement of the existing building by a horizontal displacement restraint means installed between the mountain wall and the existing building. By excavating to the depth that reaches the bottom and excavating the lower ground of the direct foundation and constructing seismic isolation pits around and below the underground part of the existing building, and work in the seismic isolation pit, A step of providing a reinforcing mat for directly reinforcing the foundation, driving a pile into the lower ground of the seismic isolation pit, and temporarily supporting the existing building via the reinforcing mat by the pile, and a new installation at the bottom of the seismic isolation pit Providing a base as a foundation A step of interposing a seismic isolation device between the board and the reinforcing mat, and then releasing a temporary support by the pile and supporting the existing building by the seismic isolation device via the reinforcing mat. To do.

  In the present invention, for the existing building group consisting of a plurality of existing buildings arranged in proximity, the seismic isolation pits are provided around and under the basement of the entire existing building group, and the direct foundation of each existing building is provided. It is also possible to integrally provide a reinforcing mat that reinforces the existing building group so as to reinforce the entire existing building group.

  It is also conceivable that an annular outer mountain retaining wall surrounding the mountain retaining wall is provided outside the mountain retaining wall as necessary.

  Furthermore, it is possible to make the seismic isolation pit function as a water tank so that the stored load causes buoyancy to act on the existing building to reduce the support load by the seismic isolation device.

  According to the seismic isolation method of the present invention, it is possible to obtain an excellent seismic isolation effect for an existing building without performing seismic reinforcement for the existing building and its installed equipment, and greatly improve the seismic performance for the existing building. In addition to what can be done, when constructing a seismic isolation pit, a mountain retaining wall is provided to surround the existing building and a horizontal displacement restraint is provided between the mountain retaining wall and the existing building. Even if an earthquake occurs, it is possible to effectively prevent the occurrence of excessive horizontal displacement in the existing building, so that not only the construction safety can be secured sufficiently, but the existing building and its installed equipment are not damaged by the earthquake. Therefore, it is possible to make the base isolation while using an existing building, which is optimal as a base isolation method for a nuclear power plant, for example.

  In particular, when targeting a group of existing buildings in which multiple existing buildings are closely arranged, the entire direct foundation of each existing building is integrated with a robust reinforcement mat, and then the entire building is integrated with a seismic isolation device. As a result, the entire existing building group can be efficiently seismically isolated, and if each existing building is isolated independently, the relative relationship between the existing buildings is required. It is not necessary to consider the horizontal displacement.

  Further, if an annular outer mountain retaining wall is constructed outside the mountain retaining wall, the outer mountain retaining wall can effectively resist the earth pressure, so that the construction safety can be ensured.

  Furthermore, by making the seismic isolation pit function as a water tank and using the so-called floating-type seismic isolation system that uses the buoyancy of the stored water, the support load by the seismic isolation device can be reduced, and the damping effect by the stored water is expected It is also possible.

An embodiment for applying the seismic isolation method of the present invention to an existing nuclear power plant for seismic isolation will be described with reference to FIGS.
As shown in FIG. 1, the nuclear power plant that is subject to seismic isolation in this embodiment is composed of an existing building group A in which a large number of existing buildings 1 are arranged close to each other, and the foundations of the individual existing buildings 1 are all In this embodiment, as shown in FIG. 6, in order to make the entire existing building group A seismically isolated as a whole, in this embodiment, In addition to the seismic isolation pit 2 at the bottom, a robust reinforcement mat 3 that connects the existing direct foundations of each existing building 1 together, and a base 4 as a new foundation for the entire existing building group A, The main purpose is to support the entire existing building group A with a seismic isolation device 5 such as a laminated rubber installed between the reinforcing mat 3 and the bottom panel 4.

In this embodiment, first, as shown in FIG. 2, the mountain retaining wall 10 surrounding the entire existing building group A is constructed. The mountain retaining wall 10 is constructed in a shape that conforms to the outline of the entire existing building group A, but the interval between the mountain retaining wall 10 and the outer periphery of the existing building 1 ensures a desired seismic isolation clearance, and It is set to such an extent that the ground around and below the existing building group A can be excavated through the interval.
The structure of the retaining wall 10 and its construction method in the present embodiment are arbitrary, but in any case, in addition to having a sufficient retaining function when excavating the inside, the horizontal displacement restraining means 12 described later. At the same time, it is necessary to be able to restrain the horizontal displacement of the existing building 1 during the construction. Therefore, as the structure of the mountain retaining wall 10, for example, an underground wall can be suitably used.
In the present embodiment, an annular outer mountain retaining wall 11 is further constructed outside the mountain retaining wall 10, and the mountain retaining wall 10 and the outer mountain retaining wall 11 are connected at important points. The outer outer mountain retaining wall 11 resists earth pressure, and the inner mountain retaining wall 10 secures the mountain retaining function at the time of excavation and the horizontal displacement restraining function for the existing building 1, so that in the event of construction It is possible to ensure sufficient safety even in the event of an earthquake. In addition, although the structure of the outer mountain retaining wall 11 is also arbitrary, it is preferably an underground continuous wall.

Next, as shown in FIG. 3, excavation is performed directly between the mountain retaining wall 10 and the existing building 1 until reaching the depth of the foundation, and further, the lower ground of the existing building 1 is horizontally oriented as shown in FIG. Excavating and building seismic isolation pit 2 around the basement of the entire existing building group A.
At that time, as shown in FIG. 3, a cut beam or a temporary floor as the horizontal displacement restraining means 12 is installed in multiple stages between the mountain retaining wall 10 and the existing building 1. As a result, the mountain retaining function by the mountain retaining wall 10 is fully secured, and the horizontal displacement of the existing building 1 can be reliably ensured by the horizontal displacement restraining means 12 and the mountain retaining wall 10 even in the event of an earthquake during construction. Therefore, it is possible to effectively prevent earthquake damage to the existing building 1 and its internally installed devices as well as ensuring construction safety.

As shown in FIG. 4, when the seismic isolation pit 2 is constructed by excavating the lower ground of the existing building 1 in the horizontal direction, the existing direct foundation is The reinforcement mat 3 to be reinforced is constructed, and a pile 13 is driven into the lower ground of the seismic isolation pit 2, and the existing building 1 is temporarily supported by the pile 13 through the reinforcement mat 3.
The reinforcing mat 3 not only reinforces the direct foundation of each existing building 1 but also connects the direct foundations of the existing buildings 1 together to support the existing building group A as a whole. Therefore, the structure may be a reinforced concrete structure.
In addition, the construction of the pile 13 needs to be carried out within the range of the height of the seismic isolation pit 2, and therefore construction of a long pile body is difficult. The steel pipe pile press-in method that press-fits into the ground while sequentially connecting in the seismic pit 2 can be suitably employed.

The seismic isolation pit 2 is constructed by the above process, and the entire reinforcing mat 3 that supports the entire existing building group A is constructed at the upper part of the seismic isolation pit 2. By constructing, the entire existing building group A is temporarily supported by the piles 13 via the reinforcing mat 3.
After that, or in parallel with the above-described process, a reinforced concrete base 4 is constructed on the entire bottom surface of the seismic isolation pit 2 as a new foundation for the entire existing building group A as shown in FIG.

As shown in FIG. 6, the seismic isolation device 5 such as laminated rubber is arranged between the bottom plate 4 and the reinforcing mat 3, and finally the pile head 13 is removed by removing the temporary support by the pile 13 so that the existing building is removed. If the entire group A is seismically isolated by the seismic isolation device 5 and the horizontal restraining means 12 is removed, the seismic isolation process is completed.
In addition, when it is necessary to provide the condensate pit 14 as shown by a chain line in FIG. 6, it may be provided below the bottom board 4, and the construction may be performed simultaneously with the construction of the bottom board 4.

According to the seismic isolation method of the above embodiment, nuclear power generation can be performed only by external work without performing seismic reinforcement for the existing building 1 and its internal equipment, and without any work from inside the existing building. The entire site can be seismically isolated, greatly improving facility safety against earthquakes.
In particular, when the seismic isolation pit 2 is constructed, not only the mountain retaining wall 10 is provided so as to surround the entire existing building group A, but also the horizontal displacement restraining means 12 between the mountain retaining wall 10 and the existing building 1. Therefore, even if an earthquake occurs during construction, it is possible to effectively prevent an excessive horizontal displacement of the existing building 1, so that not only the construction safety can be sufficiently secured but also the existing building 1 and its interior There is no earthquake damage to the installed equipment, so it is possible to make seismic isolation while operating the nuclear power plant.

  In addition, since the entire direct foundation of the existing building 1 is integrated with the robust reinforcement mat 3 and the whole is seismically isolated and supported by the seismic isolation device 5, the entire existing nuclear power plant is efficiently exempted. It can be seismicized, and when each existing building 1 is isolated independently, it is not necessary to consider the relative horizontal displacement between each existing building, and it is exempted from the piping straddling between each building. There is no need to install seismic couplings.

Although one embodiment of the present invention has been described above, the above embodiment is merely a preferred example, and the present invention is not limited to the above embodiment. For example, various applications and Deformation is possible.
The above embodiment is an application example in the case of seismic isolation of an existing nuclear power plant, but the present invention is not limited to the nuclear power plant and can be widely applied to existing buildings of various uses, scales, and forms.
Moreover, in the said embodiment, after connecting each existing building 1 integrally with the connection mat 3 for the several existing building 1 arrange | positioned closely, the whole existing building group A is collectively put together via the reinforcement mat 3 Although the seismic isolation support is provided, the present invention is not limited to such a case, and can naturally be applied to a case where the seismic isolation is applied only to a single existing building that is independently constructed.

  Moreover, it is also possible to make it a so-called floating type seismic isolation by the seismic isolation method of the present invention. That is, as shown in FIG. 7, the seismic isolation pit 2 in the above embodiment functions as a water tank, and the buoyancy caused by the stored water in the seismic isolation pit 2 is applied to the existing building 1, thereby supporting load by the seismic isolation device 5. In addition, it is possible to expect a damping effect due to stored water.

  Further, it is preferable to further provide an annular outer mountain retaining wall 11 outside the mountain retaining wall 10 as in the above embodiment, but the outer mountain retaining wall 11 may be omitted depending on the ground conditions, or the In the case where the installation space for the annular outer mountain retaining wall 11 cannot be secured, it is conceivable that the mountain retaining wall 10 is supported by a ground anchor 15 instead, for example, as shown in FIG.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the seismic isolation method of the present invention, and is a diagram showing a nuclear power plant as an existing building group to be seismically isolated. It is a figure which shows the state which constructed | assembled the mountain retaining wall and the outer contour mountain retaining wall. It is a figure which shows the state which is constructing the seismic isolation pit. It is a figure which shows the state which is constructing the reinforcement mat and the pile while constructing the seismic isolation pit. It is a figure which shows the state which the construction of the seismic isolation pit, the reinforcement mat, the pile, and the bottom panel was completed. It is a figure which shows the state which seismic isolation was completed as well. It shows a modification and shows an example in the case of floating body seismic isolation. FIG. 11 is a diagram showing another modification, and showing an example in which an annular outer mountain retaining wall is omitted and the mountain retaining wall is supported by a ground anchor.

Explanation of symbols

A existing building group 1 existing building 2 seismic isolation pit 3 reinforcement mat 4 bottom 5 seismic isolation device 10 mountain retaining wall 11 outer wall retaining wall 12 horizontal displacement restraint means 13 pile 14 condensate pit 15 earth anchor

Claims (4)

It is a seismic isolation method for existing buildings whose foundation structure is directly based,
Constructing a mountain retaining wall surrounding the existing building along the periphery of the existing building to be seismically isolated;
The ground displacement between the existing building and the mountain retaining wall reaches directly below the foundation while restraining the horizontal displacement of the existing building by the horizontal displacement restraining means installed between the mountain retaining wall and the existing building. Excavating to the depth and excavating the lower ground of the direct foundation to construct seismic isolation pits around and below the basement of the existing building;
A reinforcement mat that reinforces the existing direct foundation is provided by work in the seismic isolation pit, and a pile is driven into the lower ground of the seismic isolation pit and the existing building is temporarily supported by the pile via the reinforcement mat. Process,
After providing a base as a new foundation at the bottom of the seismic isolation pit and interposing a base isolation device between the base and the reinforcing mat, the temporary support by the pile is released and the base isolation device And a process for supporting an existing building through a reinforcing mat. The seismic isolation method according to claim 1,
Reinforcement mat for reinforcing existing foundations for the existing building group consisting of a plurality of existing buildings arranged in the vicinity and providing the seismic isolation pits around and below the basement of the entire existing building group and reinforcing the direct foundation of each existing building A seismic isolation method characterized in that the existing building group is integrally provided so as to reinforce the entire existing building group. The seismic isolation method according to claim 1 or 2,
A seismic isolation method characterized in that an annular outer mountain retaining wall surrounding the mountain retaining wall is provided outside the mountain retaining wall. The seismic isolation method according to claim 1, 2 or 3,
A seismic isolation method characterized in that the seismic isolation pit is caused to function as a water tank, and the stored load causes buoyancy to act on the existing building to reduce the support load by the seismic isolation device.

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