JP2013032684A - Foundation form changing method for existing building - Google Patents

Foundation form changing method for existing building Download PDF

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Publication number
JP2013032684A
JP2013032684A JP2012019458A JP2012019458A JP2013032684A JP 2013032684 A JP2013032684 A JP 2013032684A JP 2012019458 A JP2012019458 A JP 2012019458A JP 2012019458 A JP2012019458 A JP 2012019458A JP 2013032684 A JP2013032684 A JP 2013032684A
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Prior art keywords
pile
existing
pressure
foundation
existing building
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JP5854506B2 (en
Inventor
Satoru Kusaka
哲 日下
Kohei Kishimoto
光平 岸本
Tamehiro Araki
爲博 荒木
Akira Naito
陽 内藤
Kazutaka Kamimura
一貴 上村
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Takenaka Komuten Co Ltd
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Takenaka Komuten Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a foundation form changing method for an existing building, capable of executing foundation base isolation renovation of the existing building without being adversely affected by soundness and construction quality of an existing pile for supporting the existing building.SOLUTION: A lower part of an existing building 1 supported by a pile foundation is excavated to expose a footing 2 and an existing pile 3, a pressure-proof board 9 is constructed at an excavation bottom 6 in the state of being structurally edge-cut from the existing pile 3, and then a pile head of the existing pile 3 is cut and removed in the state of supporting an upper load by the pressure-proof board 9 through a jack 11. Thereafter, a seismic isolator C is installed between the pressure-proof board 9 and the footing 2. Thus, the existing building 1 is base-isolated and a foundation form is changed from a pile foundation to a direct foundation by the pressure-proof board 9.

Description

本発明は、既存建物の基礎形式変更方法に関し、詳しくは、杭基礎で支持された既存建
物を基礎免震改修する場合に好適な基礎形式の変更方法に関する。 The present invention relates to a method for changing the foundation type of an existing building, and more particularly, to a method for changing a foundation type suitable for base-isolation repair of an existing building supported by a pile foundation.

杭基礎で支持された既存建物を基礎免震改修する場合、従来では、既存建物の下方を掘
削してフーチング及び既存杭を露出させ、掘削底に構築した耐圧盤によりジャッキを介し
て上部荷重を支持した状態で、既存杭の杭頭部を切断撤去し、切断した杭上部に構築した
免震装置支承部（下架台）とフーチング下面に設けた上架台との間に免震装置を挿入して
おり、特許文献１、２に見られるように、基礎免震改修後も建物を既存杭で支持するよう
に構成されていた。 Conventionally, when an existing building supported by a pile foundation is to be seismically isolated, the lower part of the existing building is excavated to expose the footing and the existing pile, and the upper load is applied via a jack with a pressure plate built at the bottom of the excavation. In the supported state, the pile head of the existing pile is cut and removed, and the seismic isolation device is inserted between the base isolation device support (lower frame) built on the upper part of the cut pile and the upper frame provided on the bottom of the footing. As seen in Patent Documents 1 and 2, the building was configured to be supported by existing piles even after the foundation seismic isolation.

そのため、例えば、既存杭が施工精度の問題などで当初の設計図書よりも芯ズレを起こ
している場合や、コンクリート品質の経年劣化、杭頭切断時の衝撃や既存杭にアンカー部
材を打ち込むことによって、既存杭の損傷（杭コンクリートのひび割れ等）が生じている
場合など、既存杭の健全性に問題がある場合には、地震時に派生する応力により、免震装
置や耐圧盤に構造的に悪影響を及ぼす可能性があった。 Therefore, for example, when the existing pile has a misalignment from the original design book due to problems in construction accuracy, etc., deterioration of concrete quality over time, impact at the time of cutting the pile head or driving anchor members into the existing pile If there is a problem with the soundness of existing piles, such as damage to existing piles (such as cracks in pile concrete), structurally adverse effects on seismic isolation devices and pressure panels due to stress derived from the earthquake There was a possibility of affecting.

尚、建物の建て替え時に既存杭を新築建物の杭（新築建物の直接基礎を支持する杭）と
して再利用する工法においては、既存杭の健全性に問題があっても、新たな直接基礎とな
る耐圧盤に構造的に悪影響を及ぼさないようにするために、既存杭と耐圧盤との間に、鉛
直力は伝達するが地震時水平力は伝達しない手段、又は、鉛直力は伝達するが地震時曲げ
モーメントは伝達しない手段を設ける発明が、特許文献３によって提案されている。 In the method of reusing existing piles as piles for new buildings (pile that supports the direct foundation of new buildings) when rebuilding the building, even if there is a problem with the soundness of the existing piles, it becomes a new direct foundation. In order not to have a structural adverse effect on the pressure platen, a means to transmit vertical force but not horizontal force during an earthquake between existing piles and pressure platen, or means to transmit vertical force but not earthquake Patent Document 3 proposes an invention in which a means for transmitting no bending moment is provided.

この発明を、既存建物の基礎免震改修に応用すれば、既存杭の健全性に問題があっても
、地震時に派生する応力による免震装置や耐圧盤への悪影響を回避できると思われる。し
かしながら、これによる場合は、基礎免震改修に必要な本来の免震装置に加え、既存杭へ
の地震時水平力を伝達させないようにするための免震装置、又は、既存杭への地震時曲げ
モーメント伝達させないようにするためのピン支承部材が付加されることになるため、構
成部材が増え、コストが高く付くことになる。 If this invention is applied to the basic seismic isolation repair of an existing building, even if there is a problem with the soundness of the existing pile, it seems that the adverse effects on the seismic isolation device and the pressure panel due to the stress derived during the earthquake can be avoided. However, in this case, in addition to the original seismic isolation device necessary for basic seismic isolation repair, the seismic isolation device for preventing the horizontal force during the earthquake from being transmitted to the existing pile, or the earthquake to the existing pile Since a pin support member for preventing the bending moment from being transmitted is added, the number of components increases and the cost increases.

特開２００６−３４８６９０号公報JP 2006-348690 A 特開平９−１２５７０５号公報JP-A-9-125705 特開２００２−４７６６８号公報JP 2002-47668 A

本発明は、上記の問題点を踏まえてなされたものであって、その目的とするところは、
既存建物を支持する既存杭の健全性や施工品質による悪影響を受けることなく既存建物の
基礎免震改修を行えるようにした既存建物の基礎形式変更方法を提供することにある。 The present invention has been made in view of the above-mentioned problems, and the object is as follows.
The object is to provide a method for changing the foundation type of an existing building so that the existing building can be subjected to base isolation isolation without being adversely affected by the soundness and construction quality of existing piles that support the existing building.

上記の目的を達成するために、本発明が講じた技術的手段は、次の通りである。即ち、
請求項１に記載の発明による既存建物の基礎形式変更方法は、杭基礎で支持された既存建
物の下方を掘削してフーチング及び既存杭を露出させ、掘削底に耐圧盤を既存杭と構造的
に縁切りされた状態に築造した後、当該耐圧盤によりジャッキを介して上部荷重を支持し
た状態で、既存杭の杭頭部を切断撤去し、しかる後、耐圧盤とフーチングとの間に鉛直力
伝達部材を設置することにより、杭基礎から耐圧盤による直接基礎に基礎形式を変更する
ことを特徴としている。 In order to achieve the above object, technical measures taken by the present invention are as follows. That is,
The method for changing the foundation type of an existing building according to the first aspect of the invention is to excavate the lower part of the existing building supported by the pile foundation to expose the footing and the existing pile, and to construct the pressure platen on the bottom of the excavation with the existing pile. After being built in a state where the edge is cut, the pile head of the existing pile is cut and removed while the upper load is supported by the pressure board via the jack, and then the vertical force is applied between the pressure board and the footing. By installing a transmission member, the foundation type is changed from a pile foundation to a direct foundation using a pressure platen.

請求項２に記載の発明は、請求項１に記載の既存建物の基礎形式変更方法であって、耐
圧盤とフーチングとの間に鉛直力伝達部材として免震装置を設置することにより、既存建
物を免震化すると共に、杭基礎から耐圧盤による直接基礎に基礎形式を変更することを特
徴としている。 The invention according to claim 2 is a method for changing the basic form of the existing building according to claim 1, wherein an existing building is installed by installing a seismic isolation device as a vertical force transmission member between the pressure platen and the footing. The base type is changed from a pile foundation to a direct foundation using a pressure plate.

請求項３に記載の発明は、請求項２に記載の既存建物の基礎形式変更方法であって、既
存杭の外周に縁切り用のクッション材を巻き付けた状態で、耐圧盤のコンクリートを打設
することにより、耐圧盤と既存杭を構造的に確実に縁切りすることを特徴としている。 The invention according to claim 3 is a method for changing the basic form of the existing building according to claim 2, wherein the concrete of the pressure platen is placed in a state in which a cushion material for edge cutting is wound around the outer periphery of the existing pile. Therefore, the pressure-resistant platen and the existing pile are structurally and reliably edged.

請求項４に記載の発明は、請求項３に記載の既存建物の基礎形式変更方法であって、杭
頭部を切断撤去した後、既存杭の切断面を縁切り用のクッション材で被覆した状態で、耐
圧盤又は耐圧盤に構築される免震装置支承部のコンクリートを打設することを特徴として
いる。 The invention according to claim 4 is a method for changing the basic form of the existing building according to claim 3, wherein the pile head is cut and removed, and then the cut surface of the existing pile is covered with a cushion material for edge cutting. Then, it is characterized in that concrete of the seismic isolation device support part constructed on the pressure plate or the pressure plate is placed.

請求項１に記載の発明によれば、掘削底に築造した新設の耐圧盤が既存杭と構造的に縁
切りされているため、長期荷重の支持および地震時に発生する応力それぞれに対して新設
耐圧盤のみで成立する基礎形式となっており、既存杭の健全性や施工品質に関係なく構造
設計が可能である。また、新設の耐圧盤がジャッキによる仮受時の反力となることから、
仮受対応用の反力要素を施工時に構築する必要がなくなる。 According to the first aspect of the present invention, since the new pressure plate built on the bottom of the excavation is structurally cut off from the existing pile, the new pressure plate is supported for each of the long-term load support and the stress generated during the earthquake. It is a basic form that is formed only by the structure, and structural design is possible regardless of the soundness and construction quality of existing piles. In addition, since the new pressure-resistant panel will be the reaction force at the time of provisional reception with jack,
There is no need to construct a reaction force element for provisional support at the time of construction.

請求項２に記載の発明によれば、既存杭が施工精度の問題などで当初の設計図書よりも
芯ズレを起こしていたとしても、あるいは、コンクリート品質の経年劣化や杭頭切断時の
衝撃等により既存杭が損傷していても、免震装置の据え付けには影響せず、既存杭の施工
品質を問わず基礎免震改修が可能である。 According to the invention described in claim 2, even if the existing pile has caused a misalignment from the original design book due to problems in construction accuracy, etc., or aged deterioration of concrete quality, impact at the time of pile head cutting, etc. Even if the existing pile is damaged by the above, it does not affect the installation of the seismic isolation device, and the basic seismic isolation can be repaired regardless of the construction quality of the existing pile.

また、耐圧盤と既存杭との構造的な縁切りは、既存杭の周囲に、シアコネクターやコッ
ターなどを付加することなくコンクリートを打設するだけでも達成することが可能である
が、請求項３に記載の発明のように、既存杭の外周に縁切り用のクッション材を巻き付け
た状態で、耐圧盤のコンクリートを打設することにより、一層確実に行える。従って、健
全性に問題のある既存杭でも再利用できるように、既存杭と耐圧盤との間に鉛直力は伝達
するが地震時水平力は伝達しない免震装置や鉛直力は伝達するが地震時曲げモーメントは
伝達しないピン支承部材を設ける場合に比して、構成部材が少なくて済み、それ故、既存
建物の基礎免震改修をより容易に且つ低コストで実施することが可能である。 Further, the structural edge cutting between the pressure platen and the existing pile can be achieved only by placing concrete around the existing pile without adding a shear connector or a cotter. As in the invention described in the above, it can be performed more reliably by placing the concrete of the pressure platen in the state where the cushion material for edge cutting is wound around the outer periphery of the existing pile. Therefore, seismic isolation devices that transmit vertical force but do not transmit horizontal force during an earthquake or transmit vertical force but transmit earthquakes between existing piles and pressure-resistant panels so that existing piles with soundness can be reused. Compared to the case where a pin support member that does not transmit the bending moment is provided, the number of constituent members is small, and therefore, the basic seismic isolation of an existing building can be carried out more easily and at low cost.

請求項４に記載の発明によれば、既存杭の外周に縁切り用のクッション材を巻き付けた
状態で、耐圧盤のコンクリートを打設するだけでなく、既存杭の切断面を縁切り用のクッ
ション材で被覆した状態で、耐圧盤又は耐圧盤に構築される免震装置支承部のコンクリー
トを打設するので、耐圧盤を築造する地盤の地下水位が高い場合であっても、既存杭の外
周部からの地下水の浸入を抑制することが可能である。 According to the invention described in claim 4, not only is the concrete of the pressure platen placed in the state where the cushion material for edge cutting is wound around the outer periphery of the existing pile, but also the cushion material for edge cutting of the cut surface of the existing pile. Because the concrete of the seismic isolation device support part built on the pressure plate or the pressure plate is placed in the state covered with, even if the groundwater level of the ground where the pressure plate is built is high, the outer periphery of the existing pile It is possible to suppress the intrusion of groundwater from the ground.

本発明の実施形態を示す要部の縦断正面図である。It is a vertical front view of the principal part which shows embodiment of this invention. 図１に続く工程を説明する要部の縦断正面図である。It is a longitudinal front view of the principal part explaining the process following FIG. 図２に続く工程を説明する要部の縦断正面図である。It is a longitudinal front view of the principal part explaining the process following FIG. 図３に続く工程を説明する要部の縦断正面図である。FIG. 4 is a longitudinal front view of a main part for explaining a process following FIG. 3. 図４に続く工程を説明する要部の縦断正面図である。It is a longitudinal front view of the principal part explaining the process following FIG. 図５に続く工程を説明する要部の縦断正面図である。It is a longitudinal front view of the principal part explaining the process following FIG. 本発明の他の実施形態を示す要部の縦断正面図である。It is a vertical front view of the principal part which shows other embodiment of this invention. 本発明の他の実施形態を示す要部の縦断正面図である。It is a vertical front view of the principal part which shows other embodiment of this invention. 図８に続く工程を説明する要部の縦断正面図である。It is a longitudinal front view of the principal part explaining the process following FIG. 図９に続く工程を説明する要部の縦断正面図である。It is a longitudinal front view of the principal part explaining the process following FIG. 本発明の他の実施形態を示す要部の縦断正面図である。It is a vertical front view of the principal part which shows other embodiment of this invention. 図１１に続く工程を説明する要部の縦断正面図である。It is a longitudinal front view of the principal part explaining the process following FIG. 本発明の他の実施形態を示す要部の縦断正面図である。It is a vertical front view of the principal part which shows other embodiment of this invention. 図１３に続く工程を説明する要部の縦断正面図である。FIG. 14 is a longitudinal sectional front view of a main part for explaining a process following FIG. 13. 図１４に続く工程を説明する要部の縦断正面図である。It is a longitudinal front view of the principal part explaining the process following FIG. 図１５に続く工程を説明する要部の縦断正面図である。FIG. 16 is a longitudinal front view of a main part for explaining a process following FIG. 15. 図１６に続く工程を説明する要部の縦断正面図である。FIG. 17 is a longitudinal sectional front view of a main part for explaining a process following FIG. 16.

以下、本発明に係る既存建物の基礎形式変更方法を図面に基づいて説明する。先ず、図
１に示すように、杭基礎で支持された既存建物１の下方を掘削してフーチング（杭頭接合
部やパイルキャップと呼ばれることもある。）２及び既存杭３を露出させる。この掘削作
業は、既存建物１の敷地外周に山留め壁（図示せず）を構築した後に行われる。４は最下
階の床スラブ、５は基礎梁である。 Hereinafter, the basic form change method of the existing building which concerns on this invention is demonstrated based on drawing. First, as shown in FIG. 1, a footing (sometimes referred to as a pile head joint or a pile cap) 2 and an existing pile 3 are exposed by excavating the lower part of an existing building 1 supported by a pile foundation. This excavation work is performed after a mountain retaining wall (not shown) is constructed on the outer periphery of the site of the existing building 1. 4 is a floor slab on the lowest floor, and 5 is a foundation beam.

次に、図２に示すように、掘削底６に割栗石７及び捨てコンクリート８を敷設し、その
上に鉄筋コンクリート造の耐圧盤（マットスラブ）９を既存杭３と構造的に縁切りされた
状態に築造する。具体的には、既存杭３の切断予定レベルａから耐圧盤下端までの既存杭
外周に縁切り用のクッション材１０を巻き付けた状態で、耐圧盤９のコンクリートを打設
する。 Next, as shown in FIG. 2, the crushed stone 7 and the discarded concrete 8 are laid on the excavation bottom 6, and the reinforced concrete structure pressure slab (mat slab) 9 is structurally edged with the existing pile 3. Build on. Specifically, the concrete of the pressure platen 9 is placed in a state in which the cushion material 10 for edge cutting is wound around the outer periphery of the existing pile from the planned cutting level a of the existing pile 3 to the lower end of the pressure platen.

耐圧盤９のコンクリートが硬化したら、図３に示すように、耐圧盤９によりジャッキ１
１を介して上部荷重を支持した状態で、既存杭３の杭頭部（耐圧盤９からフーチング２下
面までの杭体部分）をワイヤーソー等で切断して撤去した後、既存杭３の切断面を縁切り
用のクッション材１０で被覆する。クッション材１０としては、例えば、厚さ５〜１０ｍ
ｍ程度の発泡樹脂シート等が使用される。 When the concrete of the pressure platen 9 is hardened, the jack 1 is pushed by the pressure platen 9 as shown in FIG.
In the state where the upper load is supported via 1, the pile head of the existing pile 3 (the pile body portion from the pressure platen 9 to the bottom surface of the footing 2) is cut and removed with a wire saw, and then the existing pile 3 is cut. The surface is covered with a cushioning material 10 for edge cutting. As the cushion material 10, for example, a thickness of 5 to 10 m
A foamed resin sheet of about m is used.

そして、図４、図５に示すように、耐圧盤９上の所定位置（免震装置設置予定位置）に
免震装置支承部（下架台）用の配筋及びコンクリート打設を行い、免震装置支承部（下架
台Ａ）を構築する。１２は免震装置支承部（下架台Ａ）の補強鉄筋、１３は補強鉄筋１２
を定着する無収縮モルタル、１４は下架台成型用型枠である。 Then, as shown in FIG. 4 and FIG. 5, reinforcing bars and concrete placement for the seismic isolation device support (base) are performed at a predetermined position on the pressure platen 9 (position where the seismic isolation device is planned to be installed). Build the device support (underlay base A). Reference numeral 12 denotes a reinforcing bar for the seismic isolation device support (the undercarriage base A), and 13 denotes a reinforcing bar 12.
A non-shrinkable mortar for fixing, and 14 is a frame for molding a base.

尚、免震装置支承部（下架台）用の補強鉄筋１２が既存杭３の杭頭部を切断除去する際
の障害にならない場合には、図７に示すように、耐圧盤９の配筋時に、耐圧盤９の肉厚内
に下端部が埋め込まれるように配筋しておき、耐圧盤用のコンクリートを打設することに
より、耐圧盤９内に定着されるようにしてもよい。 In addition, when the reinforcing bar 12 for the seismic isolation device support part (the undercarriage) does not become an obstacle when cutting and removing the pile head of the existing pile 3, as shown in FIG. Sometimes, the reinforcement is placed so that the lower end portion is embedded in the thickness of the pressure platen 9, and the concrete for the pressure platen is placed to be fixed in the pressure platen 9.

免震装置支承部（下架台Ａ）の構築後、図１２に示すように、露出した既存のフーチン
グ２の下面に、プレキャストコンクリート製の上架台Ｂをアンカーボルト１５やそれを定
着する無収縮モルタル１６等によって取り付け、下架台Ａと上架台Ｂとの間に鉛直力伝達
部材として免震装置Ｃを設置した後、ジャッキ１１を撤去する。これにより、既存建物１
が免震化されると共に、杭基礎から耐圧盤９による直接基礎に基礎形式が変更されること
になる。尚、免震装置Ｃとしては、積層ゴム系免震装置が使用されているが、これに限定
されない。 After construction of the seismic isolation device support (underlay base A), as shown in FIG. 12, the precast concrete base B is anchor bolt 15 and the non-shrink mortar that fixes it on the exposed lower surface of the footing 2. After installing the seismic isolation device C as a vertical force transmission member between the lower base A and the upper base B, the jack 11 is removed. As a result, the existing building 1
Will be seismically isolated, and the foundation type will be changed from the pile foundation to the direct foundation by the pressure platen 9. In addition, as the seismic isolation device C, although a laminated rubber type seismic isolation device is used, it is not limited to this.

上記の構成によれば、掘削底６に築造した新設の耐圧盤９が既存杭２と構造的に縁切り
されているため、長期荷重の支持および地震時に発生する応力それぞれに対して新設耐圧
盤９のみで成立する基礎形式となっており、既存杭２の健全性や施工品質に関係なく構造
設計が可能である。即ち、既存杭２が施工精度の問題などで当初の設計図書よりも芯ズレ
を起こしていたとしても、あるいは、コンクリート品質の経年劣化や杭頭切断時の衝撃等
により既存杭２が損傷していても、免震装置Ｃの据え付けには影響せず、既存杭２の施工
品質を問わず基礎免震改修が可能である。また、新設の耐圧盤９がジャッキ１１による仮
受時の反力となることから、仮受対応用の反力要素を施工時に構築する必要がなくなる。 According to the above configuration, since the new pressure plate 9 built on the excavation bottom 6 is structurally cut off from the existing pile 2, the new pressure plate 9 is supported for each of the long-term load support and the stress generated during an earthquake. It is a basic form that is formed only by the structure, and structural design is possible regardless of the soundness and construction quality of the existing pile 2. In other words, even if the existing pile 2 has a misalignment from the original design book due to problems in construction accuracy, etc., or the existing pile 2 is damaged due to deterioration of concrete quality over time or impact at the time of cutting the pile head, etc. However, it does not affect the installation of the seismic isolation device C, and the basic seismic isolation repair is possible regardless of the construction quality of the existing pile 2. Moreover, since the newly installed pressure-resistant panel 9 becomes a reaction force at the time of provisional reception by the jack 11, it is not necessary to construct a reaction force element for provisional reception at the time of construction.

耐圧盤９と既存杭２との縁切りは、既存杭２の外周に縁切り用のクッション材１０を巻
き付けた状態で、耐圧盤９のコンクリートを打設するといった手段によって容易かつ確実
に行えるので、健全性に問題のある既存杭でも再利用できるように、既存杭と耐圧盤との
間に鉛直力は伝達するが地震時水平力は伝達しない免震装置や鉛直力は伝達するが地震時
曲げモーメントは伝達しないピン支承部材を設ける場合に比して、構成部材が少なくて済
み、それ故、既存建物の基礎免震改修をより低コストで実施することが可能である。 Since the edge cutting between the pressure platen 9 and the existing pile 2 can be easily and reliably performed by means of placing concrete of the pressure platen 9 with the cushioning material 10 for edge cutting wound around the outer periphery of the existing pile 2, it is sound. The seismic isolation device that transmits vertical force but not horizontal force during an earthquake or transmits vertical force but transmits the bending force during an earthquake, so that existing piles with problems can be reused. Compared with the case where a pin bearing member that does not transmit is provided, the number of constituent members is small, and therefore, it is possible to carry out basic seismic retrofitting of an existing building at a lower cost.

殊に、上記の構成によれば、既存杭２の外周に縁切り用のクッション材１０を巻き付け
た状態で、耐圧盤９のコンクリートを打設するだけでなく、既存杭２の切断面を縁切り用
のクッション材１０で被覆した状態で、耐圧盤９に構築される免震装置支承部（下架台Ａ
）のコンクリートを打設するので、耐圧盤９を築造する地盤の地下水位が高い場合であっ
ても、既存杭２の外周部からの地下水の浸入を抑制することが可能である。 In particular, according to the above configuration, not only the concrete of the pressure platen 9 is placed in the state where the cushion material 10 for edge cutting is wound around the outer periphery of the existing pile 2, but also the cutting surface of the existing pile 2 is used for edge cutting. In the state covered with the cushioning material 10 of the base, the seismic isolation device support portion (the undercarriage A
), The infiltration of groundwater from the outer periphery of the existing pile 2 can be suppressed even when the groundwater level of the ground for constructing the pressure platen 9 is high.

図８〜図１０は、本発明の他の実施形態を示す。この実施形態は、耐圧盤９の天端より
も低い位置で既存杭２の切断を行う場合の施工手順を例示している。具体的には、図８に
示すように、既存杭２の切断予定レベルａから下の既存杭外周に縁切り用のクッション材
１０を巻き付け、且つ、切断予定レベルａでの切断作業に必要な作業スペースを確保する
箱型の型枠１７を設置した状態で、耐圧盤９のコンクリートを打設している。 8 to 10 show another embodiment of the present invention. This embodiment has illustrated the construction procedure in the case of cutting the existing pile 2 in the position lower than the top edge of the pressure | voltage resistant board 9. FIG. Specifically, as shown in FIG. 8, the cushion material 10 for edge cutting is wound around the outer periphery of the existing pile below the planned cutting level a of the existing pile 2, and the work necessary for the cutting work at the planned cutting level a The concrete of the pressure platen 9 is placed in a state where the box-shaped formwork 17 that secures the space is installed.

そして、耐圧盤９のコンクリートが硬化したら、図９に示すように、耐圧盤９によりジ
ャッキ１１を介して上部荷重を支持した状態で、既存杭３の杭頭部（切断予定レベルａか
らフーチング２下面までの杭体部分）をワイヤーソー等で切断して撤去する。 When the concrete of the pressure platen 9 is cured, as shown in FIG. 9, the pile head of the existing pile 3 (the footing 2 from the planned cutting level a) is supported with the upper load supported by the pressure platen 9 via the jack 11. Cut the pile body part to the bottom surface with a wire saw etc. and remove it.

しかる後、図１０に示すように、箱型の型枠１７を撤去すると共に、既存杭３の切断面
を縁切り用のクッション材１０で被覆した状態で、箱型の型枠１７により形成された凹部
に免震装置支承部（下架台Ａ）の補強鉄筋１２の配筋とコンクリート打設を行い、さらに
、その上部にコンクリートを増し打ちして、免震装置支承部（下架台Ａ）を構築している
。箱型の型枠１５は、耐圧盤９のコンクリートが硬化すれば任意の時点で解体撤去できる
が、図示のように、既存杭２の切断後に撤去することが望ましい。その他の構成や作用は
、図１〜図６の実施形態と同じであるため、説明を省略する。 After that, as shown in FIG. 10, the box-shaped formwork 17 was removed, and the cut surface of the existing pile 3 was covered with the cushioning material 10 for edge cutting, and the box-shaped formwork 17 was formed. Reinforcement of the reinforcing bar 12 of the seismic isolation device support (underlaying platform A) and concrete placement in the recess, and further injecting concrete into the upper part, construction of the seismic isolation device support (underlaying platform A) doing. The box-shaped form 15 can be dismantled and removed at an arbitrary time if the concrete of the pressure-resistant board 9 is hardened, but it is desirable to remove it after cutting the existing pile 2 as shown in the figure. Other configurations and operations are the same as those in the embodiment of FIGS.

図１１、図１２は、本発明の他の実施形態を示す。この実施形態は、既存建物１に地下
１階を増築する場合の施工手順を示している。具体的には、図１１に示すように、杭基礎
で支持された既存建物１の下方を地下１階の増築に必要な深度まで掘削してフーチング２
及び既存杭３を露出させ、掘削底６に耐圧盤９を既存杭３と構造的に縁切りされた状態に
築造した後、図１２に示すように、耐圧盤９によりジャッキ１１を介して上部荷重を支持
した状態で、既存杭３の杭頭部（耐圧盤９からフーチング２下面までの杭体部分）をワイ
ヤーソー等で切断して撤去した後、耐圧盤９とフーチング２との間に鉛直力伝達部材とし
て柱Ｄを設置することにより、地下１階を構築すると共に、杭基礎から耐圧盤による直接
基礎に基礎形式を変更することを特徴としている。１８は柱用型枠、１９はジャッキ受け
台である。その他の構成や作用は先の実施形態と同じであるため、説明を省略する。 11 and 12 show another embodiment of the present invention. This embodiment has shown the construction procedure in the case of extending the 1st basement floor in the existing building 1. FIG. Specifically, as shown in FIG. 11, the bottom of the existing building 1 supported by the pile foundation is excavated to the depth necessary for the extension of the first basement floor, and the footing 2
Then, after exposing the existing pile 3 and constructing the pressure platen 9 on the excavation bottom 6 in a state in which the existing pile 3 is structurally cut off, the upper load is applied via the jack 11 by the pressure platen 9 as shown in FIG. After the pile head of the existing pile 3 (pile body part from the pressure platen 9 to the bottom surface of the footing 2) is cut and removed with a wire saw or the like, the vertical between the pressure platen 9 and the footing 2 is removed. By installing the column D as a force transmission member, the first floor underground is constructed, and the foundation type is changed from a pile foundation to a direct foundation using a pressure platen. Reference numeral 18 is a column form, and 19 is a jack cradle. Since other configurations and operations are the same as those of the previous embodiment, description thereof is omitted.

図１３〜図１７は、本発明の他の実施形態を示す。この実施形態は、掘削底６に割栗石
７及び捨てコンクリート８を敷設し、その上に鉄筋コンクリート造の耐圧盤（マットスラ
ブ）９を既存杭３と構造的に縁切りされた状態に築造するにあたり、上述した各々の実施
形態のように、既存杭３の切断予定レベルａから耐圧盤下端までの既存杭外周に縁切り用
のクッション材１０を巻き付けることなく、耐圧盤９のコンクリートを打設する点に特徴
がある。 13 to 17 show another embodiment of the present invention. In this embodiment, the crushed stone 7 and the discarded concrete 8 are laid on the excavation bottom 6, and the reinforced concrete pressure board (mat slab) 9 is constructed on the existing pile 3 so as to be structurally cut off. As in the above-described embodiments, the concrete of the pressure platen 9 is placed without wrapping the cushion material 10 for edge cutting around the existing pile outer periphery from the planned cutting level a of the existing pile 3 to the bottom of the pressure platen. There are features.

即ち、既存杭３が、例えば、ＰＣパイル（プレストレストコンクリート杭）やその他の
既製コンクリート、表面が平滑な場所打ちコンクリート杭などである場合、その周囲に、
後からコンクリートを打設しても、打ち継ぎ面（杭外周面）での付着力が弱く、打ち継ぎ
面に鉄筋等によるシアコネクターやコッターなどを付加しなければ、構造的に一体化しな
い。 That is, when the existing pile 3 is, for example, PC pile (prestressed concrete pile) or other ready-made concrete, a cast-in-place concrete pile with a smooth surface,
Even if concrete is placed afterwards, the adhesive strength on the joining surface (pile outer peripheral surface) is weak, and it will not be structurally integrated unless a shear connector or cotter such as a reinforcing bar is added to the joining surface.

図１３〜図１７の実施形態では、この事象を積極的に利用して、免震改修時に既存建物
の基礎形式を変更するものであり、次の手順により施工している。 In embodiment of FIGS. 13-17, this phenomenon is utilized actively, the basic form of the existing building is changed at the time of seismic isolation repair, and it constructs by the following procedures.

先ず、図１と同様に、杭基礎で支持された既存建物１の下方を掘削してフーチング２及
び既存杭３を露出させた後、図１３に示すように、掘削底６に割栗石７及び捨てコンクリ
ート８を敷設し、その上に鉄筋コンクリート造の耐圧盤（マットスラブ）９を築造するた
めのコンクリートを切断予定レベルａまで打設する。このコンクリート打設は、既存杭３
の切断予定レベルａから耐圧盤下端までの既存杭外周に縁切り用のクッション材１０を巻
き付けることなく行う。 First, similarly to FIG. 1, after excavating the lower part of the existing building 1 supported by the pile foundation to expose the footing 2 and the existing pile 3, as shown in FIG. Abandoned concrete 8 is laid, and concrete for constructing a reinforced concrete pressure-resistant panel (mat slab) 9 is placed up to a planned cutting level a. This concrete placement is the existing pile 3
This is performed without wrapping the cushion material 10 for edge cutting around the existing pile outer periphery from the planned cutting level a to the lower end of the pressure platen.

耐圧盤９のコンクリートが硬化したら、図１４に示すように、耐圧盤９によりジャッキ
１１を介して上部荷重を支持した状態で、既存杭３の杭頭部（耐圧盤９からフーチング２
下面までの杭体部分）をワイヤーソー等で切断して撤去した後、既存杭３の切断面に縁切
り用のクッション材１０を敷設する。クッション材１０としては、例えば、厚さ５〜１０
ｍｍ程度の発泡樹脂シート等を既存杭３の径に合わせて成型又は裁断したものが使用され
る。既存杭３が、ＰＣパイルのような中空構造の既製コンクリートである場合、図１４に
おける左側の既存杭３で例示するように、切断面近くの中空部に充填用コンクリート２０
を打設し、多少の押圧力が加わっても、クッション材１０が中空部に落ち込まないように
する。 When the concrete of the pressure platen 9 is cured, as shown in FIG. 14, the pile head of the existing pile 3 (the footing 2 from the pressure platen 9 is supported with the upper load supported by the pressure platen 9 via the jack 11.
After cutting and removing the pile body part to the lower surface with a wire saw or the like, the cushion material 10 for edge cutting is laid on the cut surface of the existing pile 3. As the cushion material 10, for example, a thickness of 5 to 10
A foamed resin sheet or the like of about mm is molded or cut according to the diameter of the existing pile 3 is used. When the existing pile 3 is a ready-made concrete with a hollow structure such as a PC pile, as illustrated in the existing pile 3 on the left side in FIG.
So that the cushion material 10 does not fall into the hollow portion even if a slight pressing force is applied.

そして、図１５、図１６に示すように、耐圧盤９上の所定位置（免震装置設置予定位置
）に免震装置支承部（下架台）用の配筋及びコンクリート打設を行い、免震装置支承部（
下架台Ａ）を構築する。１２は免震装置支承部（下架台Ａ）の補強鉄筋、１３は補強鉄筋
１２を定着する無収縮モルタル、１４は下架台成型用型枠である。 Then, as shown in FIG. 15 and FIG. 16, reinforcing bars and concrete placement for the seismic isolation device support section (underlay) are performed at a predetermined position on the pressure platen 9 (position where the seismic isolation device is planned to be installed). Device support (
Build the undercarriage A). Reference numeral 12 denotes a reinforcing reinforcing bar for the seismic isolation device support (the undercarriage A), 13 denotes a non-shrink mortar for fixing the reinforcing reinforcing bar 12, and 14 denotes a form for forming the undercarriage.

尚、免震装置支承部（下架台）用の補強鉄筋１２が既存杭３の杭頭部を切断除去する際
の障害にならない場合には、図７と同様に、耐圧盤９の配筋時に、耐圧盤９の肉厚内に下
端部が埋め込まれるように配筋しておき、耐圧盤用のコンクリートを打設することにより
、耐圧盤９内に定着されるようにしてもよい。 If the reinforcing bar 12 for the seismic isolation device support (underlaying base) does not become an obstacle when cutting and removing the pile head of the existing pile 3, as in FIG. Further, the reinforcement may be arranged so that the lower end portion is embedded in the thickness of the pressure platen 9 and fixed in the pressure platen 9 by placing concrete for the pressure platen.

免震装置支承部（下架台Ａ）の構築後、図１７に示すように、露出した既存のフーチン
グ２の下面に、プレキャストコンクリート製の上架台Ｂをアンカーボルト１５やそれを定
着する無収縮モルタル１６等によって取り付け、下架台Ａと上架台Ｂとの間に鉛直力伝達
部材として免震装置Ｃを設置した後、ジャッキ１１を撤去する。これにより、既存建物１
が免震化されると共に、杭基礎から耐圧盤９による直接基礎に基礎形式が変更されること
になる。 After construction of the seismic isolation device support (underlay base A), as shown in FIG. 17, the precast concrete base B is anchor bolt 15 and the non-shrink mortar that fixes it on the exposed lower surface of the footing 2. After installing the seismic isolation device C as a vertical force transmission member between the lower base A and the upper base B, the jack 11 is removed. As a result, the existing building 1
Will be seismically isolated, and the foundation type will be changed from the pile foundation to the direct foundation by the pressure platen 9.

上記の構成によれば、既存杭３の切断予定レベルａから耐圧盤下端までの既存杭外周に
縁切り用のクッション材１０を巻き付けることなくコンクリートを打設して、耐圧盤（マ
ットスラブ）９を築造するので、クッション材１０の使用量が少なくて済み、クッション
材１０の巻き付け手間も不要であるため、より低コストで実施することが可能である。そ
の他の構成や作用は、図１〜図６の実施形態と同じであるため、説明を省略する。 According to said structure, concrete is laid around the existing pile outer periphery from the cutting plan level a of the existing pile 3 to the pressure | voltage resistant lower end, without wrapping the cushion material 10 for edge cutting, and the pressure | voltage resistant board (mat slab) 9 is made. Since it is constructed, the amount of use of the cushioning material 10 can be reduced, and the work of winding the cushioning material 10 is not required, so that it can be carried out at a lower cost. Other configurations and operations are the same as those in the embodiment of FIGS.

Ａ 下架台
Ｂ 上架台
Ｃ 免震装置（鉛直力伝達部材）
Ｄ 柱（鉛直力伝達部材）
ａ 切断予定レベル
１ 既存建物
２ フーチング
３ 既存杭
４ 床スラブ
５ 基礎梁
６ 掘削底
７ 割栗石
８ 捨てコンクリート
９ 耐圧盤
１０ クッション材
１１ ジャッキ
１２ 補強鉄筋
１３ 無収縮モルタル
１４ 下架台成型用型枠
１５ アンカーボルト
１６ 無収縮モルタル
１７ 箱型の型枠
１８ 柱用型枠
１９ ジャッキ受け台
２０ 充填用コンクリート A Lower base B Upper base C Seismic isolation device (vertical force transmission member)
D pillar (vertical force transmission member)
a Cutting scheduled level 1 Existing building 2 Footing 3 Existing pile 4 Floor slab 5 Foundation beam 6 Drilling bottom 70 Splitting stone 8 Discarded concrete 9 Pressure-resistant panel 10 Cushioning material 11 Jack 12 Reinforcing bar 13 Non-shrink mortar 14 Formwork 15 Anchor bolt 16 Non-shrink mortar 17 Box-shaped form 18 Column form 19 Jack cradle 20 Filling concrete

Claims (4)

杭基礎で支持された既存建物の下方を掘削してフーチング及び既存杭を露出させ、掘削
底に耐圧盤を既存杭と構造的に縁切りされた状態に築造した後、当該耐圧盤によりジャッ
キを介して上部荷重を支持した状態で、既存杭の杭頭部を切断撤去し、しかる後、耐圧盤
とフーチングとの間に鉛直力伝達部材を設置することにより、杭基礎から耐圧盤による直
接基礎に基礎形式を変更することを特徴とする既存建物の基礎形式変更方法。 After excavating the bottom of the existing building supported by the pile foundation to expose the footing and the existing pile, and constructing the pressure platen on the bottom of the excavation in a state where it is structurally cut off from the existing pile, via the jack with the pressure platen With the upper load supported, the pile head of the existing pile is cut and removed, and then a vertical force transmission member is installed between the pressure platen and the footing, so that the pile foundation can be changed directly to the foundation with the pressure platen. A method for changing the basic form of an existing building, characterized by changing the basic form. 耐圧盤とフーチングとの間に鉛直力伝達部材として免震装置を設置することにより、既
存建物を免震化すると共に、杭基礎から耐圧盤による直接基礎に基礎形式を変更すること
を特徴とする請求項１に記載の既存建物の基礎形式変更方法。 By installing a seismic isolation device as a vertical force transmission member between the pressure platen and the footing, the existing building is seismically isolated and the foundation type is changed from a pile foundation to a direct foundation using a pressure plate. The basic form change method of the existing building of Claim 1. 既存杭の外周に縁切り用のクッション材を巻き付けた状態で、耐圧盤のコンクリートを
打設することにより、耐圧盤と既存杭を構造的に縁切りすることを特徴とする請求項２に
記載の既存建物の基礎形式変更方法。 3. The existing pressure pile according to claim 2, wherein the pressure pile and the existing pile are structurally cut by placing concrete of the pressure plate in a state where a cushion material for edge cutting is wound around the outer periphery of the existing pile. How to change the basic form of the building. 杭頭部を切断撤去した後、既存杭の切断面を縁切り用のクッション材で被覆した状態で
、耐圧盤又は耐圧盤に構築される免震装置支承部のコンクリートを打設することを特徴と
する請求項３に記載の既存建物の基礎形式変更方法。 After the pile head is cut and removed, the concrete of the seismic isolation device support part built on the pressure plate or the pressure plate is placed with the cut surface of the existing pile covered with a cushion material for edge cutting. The method for changing the basic form of an existing building according to claim 3.
JP2012019458A 2011-06-29 2012-02-01 How to change the basic form of an existing building Expired - Fee Related JP5854506B2 (en)

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JP2012019458A JP5854506B2 (en) 2011-06-29 2012-02-01 How to change the basic form of an existing building

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JP2015209744A (en) * 2014-04-30 2015-11-24 大成建設株式会社 Seismic isolating modification method of pile foundation structure and temporary structure
JP5864686B1 (en) * 2014-09-01 2016-02-17 株式会社ダイナミックデザイン Pile foundation
CN108755744A (en) * 2018-06-25 2018-11-06 河南工业大学 Consider the structures and methods of the large diameter pile pile foundation underpinning of new and old cushion cap Influence from Eccentric
JP6430077B1 (en) * 2018-04-06 2018-11-28 トーヨーカネツ株式会社 Storage tank construction equipment

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JP2015055059A (en) * 2013-09-10 2015-03-23 株式会社竹中工務店 Beam connection structure and beam connection method
JP2015209744A (en) * 2014-04-30 2015-11-24 大成建設株式会社 Seismic isolating modification method of pile foundation structure and temporary structure
JP5864686B1 (en) * 2014-09-01 2016-02-17 株式会社ダイナミックデザイン Pile foundation
JP6430077B1 (en) * 2018-04-06 2018-11-28 トーヨーカネツ株式会社 Storage tank construction equipment
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