JP3827625B2 - Seismic control structure that allows lifting of pile tip - Google Patents

Seismic control structure that allows lifting of pile tip Download PDF

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JP3827625B2
JP3827625B2 JP2002221368A JP2002221368A JP3827625B2 JP 3827625 B2 JP3827625 B2 JP 3827625B2 JP 2002221368 A JP2002221368 A JP 2002221368A JP 2002221368 A JP2002221368 A JP 2002221368A JP 3827625 B2 JP3827625 B2 JP 3827625B2
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pile
tip
peripheral surface
concrete
outer peripheral
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JP2004060322A (en
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康博 春日
敬三 岩下
雅路 青木
秀樹 木村
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Takenaka Corp
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Description

【０００１】
【発明の属する技術分野】
この発明は、地震時に発生する構造物の浮き上がりを杭の先端部で許容する制震構造の技術分野に属する。
【０００２】
【従来の技術】
地震時に発生する構造物の浮き上がりは、通例杭頭部又は柱脚部等（地表部分）で許容する制震構造が一般的で、杭の先端部（地中部分）で許容する制震構造は見聞しない。
【０００３】
例えば、（ｉ）特開平１０−３３１１７３号公報に記載の基礎構造は、杭頭部で浮き上がりを許容する構成である。前記構造物の下部には凹部が形成されており、地震時における構造物のせん断力を確実に杭頭部へ伝達できるように、杭頭部が構造物の凹部へ嵌め込まれている。
【０００４】
（ii）特開２０００−２４０３１５公報に記載のアスペクト比が大きい建物の免震方法及び免震構造は、構造物（建物）を支持する支持版で浮き上がりを許容する構成である。前記構造物の下端部には凸部が設けられ、支持版には凹部が形成されており、地震時における構造物のせん断力を確実に支持版へ伝達できるように、前記構造物の凸部が支持版の凹部へ嵌め込まれている。
【０００５】
（iii）特開２００１−３３６３０６公報に記載の免震構造架構は、杭頭部で浮き上がりを許容する構成である。前記杭頭部には凹部が形成されており、地震時における構造物のせん断力を伝達できるように、構造物の柱の下端部が杭頭部の凹部へ嵌め込まれている。そして、浮き上がり時において、凹部内へ土砂等が侵入しないように、前記凹部の上端は杭の上端面よりも上方へ立ち上げられ、その立ち上がり部はシール材で被覆されている。
【０００６】
（iv）特開２００２−４６３２公報に記載の免震柱脚部構造は、ベースプレートへ下端部を固定した鞘管が柱脚部に立ち上げられ、前記鞘管の中に、下端部にエンドプレートを取り付けた柱が嵌め込まれ、柱脚部で浮き上がりを許容する構成である。前記エンドプレートは、鞘管へ地震時における構造物のせん断力を確実に伝達できる形状、大きさとされている。そして、通常時及び柱の下端部が浮き上がり時において、鞘管内へ土砂等が侵入しないように、前記鞘管の上端部と柱の側面との間の開口部を塞ぐ変形可能なゴム板などが設置されている。
【０００７】
【本発明が解決しようとする課題】
上述した（ｉ）〜（iv）の技術の所謂凹凸構造は、せん断力を伝達するための接触面が極めて小さいので、同凹凸構造に十分な強度を確保する必要がある。そのため、通例（ｉ）の技術では、杭頭部や構造物の凹部の周辺の鉄筋を増やすなどして補強される。（ii）の技術では、構造物の凸部や支持版の凹部の周辺の鉄筋を増やすなどして補強される。また、（iii）の技術では、柱の下端部や杭頭部の凹部の周辺の鉄筋を増やすなどして補強される。（iv）の技術では、十分に厚みのあるエンドプレートを柱へ取り付けたり、鞘管の周辺の鉄筋を増やすなどして補強される。
【０００８】
特に、（ｉ）〜(iv)の技術は、凹凸構造の凹部及び凸部のいずれもが構造物の主要部（柱や杭、支持版など）に設けているため、破壊されることは決して許されず、時として必要以上に補強される。
要するに、補強に伴う構造設計及び施工が煩雑である。
【０００９】
上記（ｉ）、（ii）の技術は、地上部分で構造物の浮き上がりを許容しているのに、浮き上がり時の土砂等の侵入を防ぐことができる構成とされていない。
【００１０】
本発明の目的は、凹凸構造において大きな接触面を確保して、同接触面に作用するせん断応力を小さくすることで、鉄筋を増やすなどして補強する必要がほとんどなく、構造設計及び施工の容易化を図り、常時健全な状態を維持することができる杭先端の浮き上がりを許容した制震構造を提供することである。
【００１１】
【課題を解決するための手段】
上記従来技術の課題を解決するための手段として、請求項１に記載した発明に係る杭先端の浮き上がりを許容した制震構造は、
アスペクト比の大きな構造物を支持する杭の先端部が到達する支持地盤に、応力伝達用コンクリートが打設され、前記応力伝達用コンクリートに杭先端部を嵌める凹部が形成されていること、
杭の先端部は前記凹部へ縁を切って嵌め込まれ、杭頭部は基礎梁と剛結されており、前記杭の先端部より上方の外周に土砂等が埋め戻されていること、
前記杭の先端面と凹部の底面とは面接触とされ、且つ杭の先端部の外周面と凹部の内周面との間にクリアランスが設けられ、杭底部にせん断力伝達用の隙間材が取り付けられ、前記隙間材の厚さを包含するクリアランスにグリースが充填されていること、
前記杭の軸方向に、同杭の先端面まで貫通された縦孔が設けられ、前記縦孔にグリースが充填されていることを特徴とする。
【００１２】
請求項２記載の発明は、請求項１に記載した杭先端の浮き上がりを許容した制震構造において、
応力伝達用コンクリートの凹部に、その内周面及び底面を形成する箱形の鋼製鞘管が設置されていること、
杭の先端部には、その外周面及び先端面を形成する箱形の鋼製鞘管がスタッドを介して一体化されており、杭の内部に設けられた縦孔の先端は前記鋼製鞘管の外側底面まで貫通されていること、
前記鋼製鞘管によって形成された杭の先端部の外周面には、同杭の先端部の外周面と応力伝達用コンクリートの凹部の内周面とのクリアランスに包含される隙間材が取り付けられていることを特徴とする。
【００１３】
請求項３記載の発明は、請求項１又は２に記載した杭先端の浮き上がりを許容した制震構造において、
杭の外周であって、応力伝達用コンクリートの略直上の埋め戻し土砂は、杭の外周面と縁を切って打設されたソイルセメントで構成されていることを特徴とする。
【００１４】
請求項４記載の発明は、請求項１又は２に記載した杭先端の浮き上がりを許容した制震構造において、
杭は先細のテーパー形状に形成されていることを特徴とする。
【００１５】
【本発明の実施形態、及び実施例】
以下に、本発明に係る杭先端の浮き上がりを許容した制震構造の実施形態を図面に基づいて説明する。
【００１６】
図１は、制震構造の浮き上がり時を概念的に示している。この制震構造は、アスペクト比の高い構造物１を支持する比較的短い（４ｍ程度の）杭２の先端部が到達する支持地盤３に、応力伝達用の鉄筋コンクリート４（以下、単に応力伝達用コンクリート４という。）が打設され、前記応力伝達用コンクリート４に杭２の先端部を嵌める凹部５が形成されている。
【００１７】
前記杭２の先端部は凹部５へ縁を切って嵌め込まれ、杭頭部は構造物１の基礎梁６と剛結されている。そして、前記杭２の先端部より上方の外周であって、応力伝達用コンクリート４の略直上部位には、浮き上がり時において杭２の外周面との摩擦力を軽減して、浮き上がりを良好に実施するために、同外周面と縁を切ったソイルセメント７が打設されている（請求項３記載の発明）。前記杭１の外周面とソイルセメント７とは面接触とされるので、地震時における構造物１のせん断力は、杭２の先端部の外周面と応力伝達用コンクリート４の凹部５の内周面との接触面、及び上記杭２の先端部より上方の外周面とソイルセメント７との接触面に作用する。即ち、杭２の外周面全体を使って構造物１のせん断力を伝達することができるので、所謂凹凸構造において大きな接触面を確保することができ、同接触面に作用するせん断応力を小さくできる。そのため、杭２の先端部や凹部５の周辺の鉄筋の数を増やなどして補強する必要がなく、施工が容易である。
【００１８】
前記杭２の先端面と応力伝達用コンクリート４の凹部５との底面とは面接触とされている。そのため、杭２の先端面全体を使って、浮き上がりによる落下衝撃力を応力伝達用コンクリート４へ伝達できる。前記応力伝達用コンクリート４は、上述のように支持地盤３上に打設されているので、前記落下衝撃力を確実に受け止めることができる。したがって、必要以上に鉄筋を配置して強度を確保する必要がなく、構造設計や施工が容易である。
【００１９】
図２は、杭部分の構造を詳細に示している。
応力伝達用コンクリート４の凹部５には、杭２の先端部外径よりも若干大きな内径を有し、凹部５の内周面及び底面を形成する箱形の鋼製鞘管８が設置されている。前記杭２の先端部も略同様に、その外周面及び先端面を形成する箱形の鋼製鞘管９がスタッド１０を介して一体化されており、この鋼製鞘管９が鋼製鞘管８の内部へ嵌め込まれている。前記鋼製鞘管８は、詳細は後述するが応力伝達用コンクリート４に凹部５を形成するための型枠として用いられ、鋼製鞘管９は杭２の先端部を形成するための型枠として用いられる。
【００２０】
前記のように嵌め込まれた杭２の先端部の外周面と凹部５の内周面との間にはクリアランスＴが設けられ、杭２の先端部の外周面下部（即ち杭底部）に前記クリアランスＴより若干薄い鋼板１２が、せん断力伝達用の隙間材として杭２の先端部の浮き上がりを許容するように取り付けられている（請求項２記載の発明）。前記鋼板１２の厚さを包含するクリアランスＴにはグリース１１が充填されている。即ち、前記鋼板１２を介して杭２の先端部の外周面と凹部５の内周面とが面接触する構成とされている。
【００２１】
前記杭２の軸方向には、浮き上がりによって杭２の先端部と凹部５との間が真空状態になり、負圧による抵抗が発生しないように、鋼製鞘管９の外側裏面まで貫通するチューブ１３が設けられ、同チューブ１３によって形成された縦孔にグリース１１が充填されている。要するに、浮き上がり時の負圧により杭２の先端面と凹部５の底面との間にグリース１１が吸い込まれ、落下する時には前記グリース１１は縦孔へ押し戻される構成とされている。
【００２２】
上述したように杭２の先端部より上方の外周面は、摩擦抵抗の少ないソイルセメント７と面接触とされているので、図１に示すように、杭２の先端部は地震時において良好に浮き上がることができ、構造物の地震応答低減効果を発揮できる。また、杭２の先端部と凹部５とのクリアランスＴにはグリース１１が充填されているので、浮き上がり時に土砂等の侵入を防ぐことができ、常時健全な状態を維持することができる。
【００２３】
上記構成の杭先端の浮き上がりを許容した制震構造の構築は、先ず、杭２の周辺に鋼製型枠１４を打設し、前記杭１の外周面周辺及び先端部下方の支持地盤３まで掘削する。前記掘削地盤の底部に捨てコンクリート１５を打設し、その上方へ落下衝撃力を受け止めるのに十分な鉄筋１６を配置する。そして、杭２の先端部を嵌め込むことができる所定の位置に鋼製鞘管８を配置して固定し、応力伝達用コンクリート４を打設して凹部５を形成する。
【００２４】
杭１の先端部の外周面及び先端面を形成する鋼製鞘管９の内面には、予めスタッド１０を設け、前記鋼製鞘管９の上端部から地表まで伸びる型枠１７を仮設する。さらに、前記鋼製鞘管９の外周面下部には、クリアランスＴより若干薄い鋼板１２を取り付ける。なお、鋼製鞘管９の底面には、チューブ１３の下端部を貫通させる孔９ａを設ける。
【００２５】
その鋼製鞘管９を鋼製鞘管８の内部へ嵌め込み、前記鋼製鞘管９の外周面と鋼製鞘管８の内周面との間のクリアランスＴに、土砂等の侵入を防ぐグリース１１を充填する。
【００２６】
前記鋼製鞘管９及び仮設した型枠１７の内部には、縦孔を形成するためのチューブ１３と鉄筋（図示を省略）を配置する。このとき、前記チューブ１３の下端部は、鋼製鞘管９の孔９ａへ貫通させ、後に打設するコンクリートが漏れ出さないように、前記孔９ａの内周とチューブ１３の外周とをしっかりと塞いでおく。一方、上端部は後に構築される基礎梁６を貫通させるのに足りる長さを地表から突出させる。そして、上記鋼製鞘管９及び仮設した型枠１７の内部へ、コンクリートを打設して杭２を構築する。
【００２７】
次に、上記鋼製型枠１４を取り除き、杭２の外周の掘削部にソイルセメント７を打設し、杭２のコンクリートとソイルセメント７とが硬化した後に型枠１７を引き抜く。つまり、杭２の外周面とソイルセメント７との縁は切られる。
【００２８】
そして、地表に突出させたチューブ１３の上端部を貫通させ、杭２の上端部と剛結するように基礎梁６を構築し、前記チューブ１３が形成する縦孔にグリース１１を充填する。
【００２９】
上記の構築方法では、応力伝達用コンクリート４及びソイルセメント７を打設するために用いる掘削用の鋼製型枠１４を一種類で済ますことができ、施工の一層の容易化を図ることができる。
【００３０】
なお、本実施形態では、型枠１７を引き抜いて撤去したが、捨て型枠として残しておいても支障はない。
【００３１】
図３は、杭先端の浮き上がりを許容する制震構造の異なる実施形態を、杭部分の構造について詳細に示している。この制震構造は、図２に示した制震構造と略同様の構成であるが、杭２の先端部から上方に向かって外径Ｒが大きくなる所謂先細テーパー形状に形成されている（請求項４記載の発明）。前記先細テーパー形状により杭２の引き抜き抵抗が軽減される。よって、図３に示す制震構造は、杭２の外周の掘削部へソイルセメント７を打設することなく、掘削土砂１８を埋め戻している。そのため施工の一層の容易化を図ることができる。
【００３２】
図４は、杭先端の浮き上がりを許容する制震構造の更に異なる実施形態を、杭部分の構造について詳細に示している。この制震構造も、図２に示した制震構造と略同様の構成とされているが、掘削部周辺の地盤１９の摩擦力が小さい場合に好適に実施されるものである。
【００３３】
具体的には、応力伝達用コンクリート４の上面２０と縁を切って、杭２の外周の掘削部へコンクリート２１を打設し、杭２と一体化されている。そのためコンクリート２１の下面と応力伝達用コンクリート４の上面２０とが面接触となり、浮き上がりによる落下衝撃力をより確実に応力伝達用コンクリート４へ伝達できる。
【００３４】
【本発明の奏する効果】
請求項１〜４に記載した発明に係る杭先端の浮き上がりを許容した制震構造は、地震のせん断力が、杭の先端部の外周面と応力伝達用コンクリートの凹部の内周面との接触面、及び杭の先端部より上方の外周面とソイルセメント等との接触面に広く作用する。即ち、杭の外周面全体を使ってせん断力を伝達できるので、所謂凹凸構造において大きな接触面を確保することができ、同接触面に作用するせん断応力を小さくできる。そのため杭の先端部や凹部の周辺の鉄筋の数を増やして補強する必要がなく、施工が容易である。
【００３５】
また、杭の先端部は地震時に良好に浮き上がり、構造物の地震応答低減効果を発揮できる。しかも、杭の先端部と凹部とのクリアランスにはグリースが充填されているので、浮き上がり時に土砂等の侵入を防ぐことができ、常時健全な状態を維持することができる。
【図面の簡単な説明】
【図１】本発明に係る杭先端の浮き上がりを許容した制震構造を示した立面図である。
【図２】杭部分の構造を詳細に示した立面図である。
【図３】異なる杭部分の構造を詳細に示した立面図である。
【図４】更に異なる杭部分の構造を詳細に示した立面図である。
【符号の説明】
１ 構造物
２ 建物の杭
３ 支持地盤
４ 応力伝達用コンクリート
５ 凹部
６ 基礎梁
７ ソイルセメント
８、９ 鋼製鞘管
１０ スタッド
１１ グリース
１２ せん断力伝達用の鋼板（隙間材）
１３ チューブ[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a technical field of a seismic control structure that allows a structure to be lifted at an end of a pile at the time of an earthquake.
[0002]
[Prior art]
In general, the lift of structures that occur during an earthquake is generally permitted to be controlled by the pile head or column base (surface part), and the vibration control structure permitted at the tip of the pile (underground part) is Don't listen.
[0003]
For example, (i) the foundation structure described in Japanese Patent Application Laid-Open No. 10-331173 is a configuration that allows the pile head to lift. A concave portion is formed in the lower portion of the structure, and the pile head is fitted into the concave portion of the structure so that the shearing force of the structure during an earthquake can be reliably transmitted to the pile head.
[0004]
(Ii) The seismic isolation method and the seismic isolation structure for a building having a large aspect ratio described in Japanese Patent Application Laid-Open No. 2000-240315 are configured to allow lifting by a supporting plate that supports a structure (building). A convex portion is provided at the lower end of the structure, and a concave portion is formed in the support plate, so that the shear force of the structure during an earthquake can be reliably transmitted to the support plate. Is fitted into the recess of the support plate.
[0005]
(Iii) The seismic isolation structure described in Japanese Patent Application Laid-Open No. 2001-336306 is a configuration that allows lifting at a pile head. A concave portion is formed in the pile head, and the lower end portion of the pillar of the structure is fitted into the concave portion of the pile head so that the shearing force of the structure during an earthquake can be transmitted. Then, the upper end of the concave portion is raised above the upper end surface of the pile so that earth and sand do not enter the concave portion when floating, and the rising portion is covered with a sealing material.
[0006]
(Iv) In the seismic isolation column pedestal structure described in Japanese Patent Application Laid-Open No. 2002-4632, a sheath tube having a lower end fixed to a base plate is raised on the column base, and the end plate is disposed at the lower end in the sheath tube. It is the structure which the column which attached is fitted and accepts floating at the column base. The said end plate is made into the shape and magnitude | size which can transmit the shearing force of the structure at the time of an earthquake to a sheath pipe reliably. Further, a deformable rubber plate or the like that closes the opening between the upper end of the sheath tube and the side surface of the column so that earth and sand do not enter the sheath tube during normal times and when the lower end of the column is lifted. is set up.
[0007]
[Problems to be solved by the present invention]
The so-called concavo-convex structure of the above-described techniques (i) to (iv) has a very small contact surface for transmitting the shearing force, so that it is necessary to ensure sufficient strength for the concavo-convex structure. For this reason, in the technique (i), the reinforcement is performed by increasing the reinforcing bars around the pile head and the concave portion of the structure. In the technique (ii), reinforcement is performed by increasing the reinforcing bars around the convex portion of the structure and the concave portion of the support plate. In the technique (iii), the reinforcement is performed by increasing the reinforcing bars around the lower end of the pillar and the concave portion of the pile head. In the technique (iv), a sufficiently thick end plate is attached to the column, or the reinforcing bars around the sheath tube are increased.
[0008]
In particular, in the techniques (i) to (iv), since both the concave and convex portions of the concavo-convex structure are provided in the main part of the structure (columns, piles, support plates, etc.), they are never destroyed. Not allowed, sometimes reinforced more than necessary.
In short, the structural design and construction accompanying reinforcement are complicated.
[0009]
The techniques (i) and (ii) described above allow the structure to float on the ground part, but are not configured to prevent intrusion of earth and sand or the like at the time of lifting.
[0010]
The object of the present invention is to secure a large contact surface in the concavo-convex structure and reduce the shear stress acting on the contact surface, so that there is almost no need to reinforce by increasing the number of reinforcing bars, and the structure design and construction is easy. The aim is to provide a seismic control structure that allows lifting of the tip of the pile that can be maintained and always kept in a healthy state.
[0011]
[Means for Solving the Problems]
As a means for solving the problems of the prior art, a vibration control structure that allows the pile tip to lift according to the invention described in claim 1,
Stress supporting concrete is placed on the supporting ground to which the tip of the pile supporting the structure having a large aspect ratio reaches, and a recess for fitting the tip of the pile to the stress transmitting concrete is formed,
The tip of the pile is fitted with the edge cut into the recess, the pile head is rigidly connected to the foundation beam, and earth and sand are backfilled on the outer periphery above the tip of the pile,
The tip end surface of the pile and the bottom surface of the recess are in surface contact, and a clearance is provided between the outer peripheral surface of the tip end of the pile and the inner peripheral surface of the recess, and a gap material for transmitting shear force is provided at the bottom of the pile. It is attached, and the clearance including the thickness of the gap material is filled with grease,
In the axial direction of the pile, a vertical hole penetrating to the tip end surface of the pile is provided, and the vertical hole is filled with grease.
[0012]
The invention according to claim 2 is a seismic control structure that allows the pile tip to lift up according to claim 1,
A box-shaped steel sheath tube that forms the inner peripheral surface and the bottom surface of the concave portion of the concrete for stress transmission is installed;
A box-shaped steel sheath tube that forms the outer peripheral surface and the tip surface of the pile is integrated with the stud, and the tip of the vertical hole provided in the pile is the steel sheath. Penetrated to the outside bottom of the tube,
A gap material included in the clearance between the outer peripheral surface of the tip of the pile and the inner peripheral surface of the concave portion of the stress transmission concrete is attached to the outer peripheral surface of the pile formed by the steel sheath tube. It is characterized by.
[0013]
The invention described in claim 3 is a seismic control structure that allows the pile tip to lift up according to claim 1 or 2,
The backfill earth and sand which is the outer periphery of the pile and is directly above the concrete for stress transmission is characterized in that it is composed of a soil cement that is placed by cutting the outer peripheral surface and the edge of the pile.
[0014]
The invention according to claim 4 is a seismic control structure that allows the pile tip to lift up according to claim 1 or 2,
The pile is formed in a tapered shape with a taper.
[0015]
[Embodiments and Examples of the Present Invention]
Hereinafter, an embodiment of a vibration control structure that allows lifting of a pile tip according to the present invention will be described with reference to the drawings.
[0016]
FIG. 1 conceptually shows when the damping structure is lifted. This seismic control structure is composed of a reinforced concrete 4 for stress transmission (hereinafter simply referred to as stress transmission structure) on a supporting ground 3 where a tip of a relatively short (about 4 m) pile 2 supporting a structure 1 having a high aspect ratio reaches. Concrete 4) is placed, and a recess 5 is formed in which the tip of the pile 2 is fitted into the concrete 4 for stress transmission.
[0017]
The tip of the pile 2 is fitted into the recess 5 by cutting the edge, and the pile head is rigidly connected to the foundation beam 6 of the structure 1. And the outer periphery above the tip of the pile 2 and substantially directly above the stress-transmitting concrete 4 reduces the frictional force with the outer peripheral surface of the pile 2 at the time of lifting, and lifts well. In order to achieve this, a soil cement 7 having an edge cut from the outer peripheral surface is cast (invention according to claim 3). Since the outer peripheral surface of the pile 1 and the soil cement 7 are in surface contact, the shearing force of the structure 1 at the time of an earthquake is the outer peripheral surface of the tip portion of the pile 2 and the inner periphery of the concave portion 5 of the stress transmission concrete 4. It acts on the contact surface with the surface and the contact surface between the outer peripheral surface above the tip of the pile 2 and the soil cement 7. That is, since the shear force of the structure 1 can be transmitted using the entire outer peripheral surface of the pile 2, a large contact surface can be secured in a so-called uneven structure, and the shear stress acting on the contact surface can be reduced. . Therefore, it is not necessary to reinforce by increasing the number of reinforcing bars around the tip of the pile 2 or the recess 5, and the construction is easy.
[0018]
The front end surface of the pile 2 and the bottom surface of the concave portion 5 of the stress transmitting concrete 4 are in surface contact. Therefore, the drop impact force due to lifting can be transmitted to the concrete 4 for stress transmission using the entire front end surface of the pile 2. Since the stress transmitting concrete 4 is placed on the support ground 3 as described above, the drop impact force can be reliably received. Therefore, it is not necessary to arrange reinforcing bars more than necessary to ensure strength, and structural design and construction are easy.
[0019]
FIG. 2 shows the structure of the pile portion in detail.
In the concave portion 5 of the stress transmission concrete 4, a box-shaped steel sheath tube 8 having an inner diameter slightly larger than the outer diameter of the tip portion of the pile 2 and forming the inner peripheral surface and the bottom surface of the concave portion 5 is installed. Yes. A box-shaped steel sheath tube 9 that forms the outer peripheral surface and the distal end surface of the pile 2 is integrated in a similar manner through a stud 10, and the steel sheath tube 9 is integrated with the steel sheath. The tube 8 is fitted inside. The steel sheath tube 8 is used as a mold for forming the recess 5 in the stress transmission concrete 4, which will be described later in detail, and the steel sheath tube 9 is a mold for forming the tip of the pile 2. Used as
[0020]
A clearance T is provided between the outer peripheral surface of the tip of the pile 2 fitted as described above and the inner peripheral surface of the recess 5, and the clearance is provided at the lower portion of the outer peripheral surface of the pile 2 (that is, the bottom of the pile). A steel plate 12 slightly thinner than T is attached as a gap material for transmitting a shearing force so as to allow the tip portion of the pile 2 to lift (the invention according to claim 2). A clearance T including the thickness of the steel plate 12 is filled with grease 11. That is, the outer peripheral surface of the tip portion of the pile 2 and the inner peripheral surface of the recess 5 are in surface contact with each other via the steel plate 12.
[0021]
In the axial direction of the pile 2, a tube that penetrates to the outer back surface of the steel sheath tube 9 so that the space between the tip of the pile 2 and the recess 5 is in a vacuum state due to floating and resistance due to negative pressure is not generated. 13 is provided, and the vertical hole formed by the tube 13 is filled with the grease 11. In short, the grease 11 is sucked between the front end surface of the pile 2 and the bottom surface of the recess 5 due to the negative pressure at the time of lifting, and when falling, the grease 11 is pushed back into the vertical hole.
[0022]
As described above, since the outer peripheral surface above the tip of the pile 2 is in surface contact with the soil cement 7 having a low frictional resistance, the tip of the pile 2 is excellent during an earthquake as shown in FIG. It can be lifted and the effect of reducing the earthquake response of the structure can be demonstrated. Further, since the clearance T between the tip portion of the pile 2 and the concave portion 5 is filled with the grease 11, it is possible to prevent intrusion of earth and sand or the like at the time of lifting, and a healthy state can be always maintained.
[0023]
The construction of the vibration control structure that allows the lifting of the tip of the pile having the above-described configuration is as follows. First, a steel mold 14 is placed around the pile 2, and the support ground 3 around the periphery of the pile 1 and below the tip is provided. Excavate. Abandoned concrete 15 is cast at the bottom of the excavated ground, and sufficient reinforcing bars 16 are placed above it to receive the drop impact force. And the steel sheath tube 8 is arrange | positioned and fixed to the predetermined position which can engage | insert the front-end | tip part of the pile 2, and the concrete 4 for stress transmission is cast, and the recessed part 5 is formed.
[0024]
Studs 10 are provided in advance on the outer peripheral surface of the front end portion of the pile 1 and the inner surface of the steel sheath tube 9 forming the front end surface, and a mold 17 extending from the upper end portion of the steel sheath tube 9 to the ground surface is temporarily installed. Further, a steel plate 12 slightly thinner than the clearance T is attached to the lower part of the outer peripheral surface of the steel sheath tube 9. In addition, the bottom surface of the steel sheath tube 9 is provided with a hole 9a that allows the lower end portion of the tube 13 to pass therethrough.
[0025]
The steel sheath tube 9 is fitted into the steel sheath tube 8 to prevent infiltration of earth and sand into the clearance T between the outer peripheral surface of the steel sheath tube 9 and the inner peripheral surface of the steel sheath tube 8. Fill with grease 11.
[0026]
Inside the steel sheath tube 9 and the temporary formwork 17, a tube 13 for forming a vertical hole and a reinforcing bar (not shown) are arranged. At this time, the lower end portion of the tube 13 penetrates into the hole 9a of the steel sheath tube 9, and the inner periphery of the hole 9a and the outer periphery of the tube 13 are firmly connected so that concrete to be placed later does not leak out. Keep it closed. On the other hand, the upper end projects a length sufficient to penetrate the foundation beam 6 to be constructed later from the ground surface. Then, concrete is cast into the steel sheath tube 9 and the temporary formwork 17 to construct the pile 2.
[0027]
Next, the steel mold 14 is removed, the soil cement 7 is placed on the excavation part on the outer periphery of the pile 2, and the mold 17 is pulled out after the concrete of the pile 2 and the soil cement 7 are cured. That is, the edge of the outer peripheral surface of the pile 2 and the soil cement 7 is cut.
[0028]
Then, the base beam 6 is constructed so as to penetrate the upper end portion of the tube 13 projecting to the ground surface and to be rigidly connected to the upper end portion of the pile 2, and the vertical hole formed by the tube 13 is filled with the grease 11.
[0029]
In the above construction method, only one type of excavation steel formwork 14 used for placing the stress transmitting concrete 4 and the soil cement 7 can be used, and the construction can be further facilitated. .
[0030]
In this embodiment, the mold 17 is pulled out and removed, but there is no problem even if it is left as a discarded mold.
[0031]
FIG. 3 shows in detail the structure of the pile part, which is a different embodiment of the damping structure that allows the pile tip to lift. This seismic control structure has substantially the same structure as the seismic control structure shown in FIG. 2, but is formed in a so-called taper taper shape in which the outer diameter R increases upward from the tip of the pile 2 (claim) Item 4). The pull-out resistance of the pile 2 is reduced by the tapered shape. Therefore, the seismic control structure shown in FIG. 3 backfills the excavated earth and sand 18 without placing the soil cement 7 in the excavated portion on the outer periphery of the pile 2. Therefore, the construction can be further facilitated.
[0032]
FIG. 4 shows in more detail the structure of the pile part, a further different embodiment of the damping structure that allows the pile tip to lift. This seismic control structure is also substantially the same as the seismic control structure shown in FIG. 2, but is suitably implemented when the frictional force of the ground 19 around the excavation part is small.
[0033]
Specifically, the upper surface 20 of the stress transmission concrete 4 is cut off from the edge, and the concrete 21 is placed on the excavation portion on the outer periphery of the pile 2 so as to be integrated with the pile 2. Therefore, the lower surface of the concrete 21 and the upper surface 20 of the stress transmission concrete 4 are in surface contact, and the drop impact force due to lifting can be transmitted to the stress transmission concrete 4 more reliably.
[0034]
[Effects of the present invention]
In the vibration control structure that allows lifting of the pile tip according to the inventions described in claims 1 to 4, the shearing force of the earthquake is a contact between the outer peripheral surface of the tip of the pile and the inner peripheral surface of the concave portion of the stress transmission concrete. It acts widely on the contact surface between the surface and the outer peripheral surface above the tip of the pile and the soil cement. That is, since the shear force can be transmitted using the entire outer peripheral surface of the pile, a large contact surface can be secured in a so-called uneven structure, and the shear stress acting on the contact surface can be reduced. Therefore, it is not necessary to reinforce by increasing the number of reinforcing bars around the tip of the pile or the recess, and the construction is easy.
[0035]
Moreover, the tip of the pile can be lifted well during an earthquake, and the effect of reducing the earthquake response of the structure can be exhibited. In addition, since the clearance between the tip portion and the concave portion of the pile is filled with grease, it is possible to prevent intrusion of earth and sand and the like when it is lifted, and it is possible to always maintain a healthy state.
[Brief description of the drawings]
FIG. 1 is an elevational view showing a vibration control structure that allows lifting of a pile tip according to the present invention.
FIG. 2 is an elevation view showing the structure of a pile portion in detail.
FIG. 3 is an elevation view showing in detail the structure of different pile portions.
FIG. 4 is an elevational view showing the structure of a different pile portion in detail.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Structure 2 Building pile 3 Support ground 4 Stress transmission concrete 5 Recess 6 Foundation beam 7 Soil cement 8, 9 Steel sheath tube 10 Stud 11 Grease 12 Steel plate for shear force transmission (gap material)
13 tubes

Claims (4)

アスペクト比の大きな構造物を支持する杭の先端部が到達する支持地盤に、応力伝達用コンクリートが打設され、前記応力伝達用コンクリートに杭先端部を嵌める凹部が形成されていること、
杭の先端部は前記凹部へ縁を切って嵌め込まれ、杭頭部は基礎梁と剛結されており、前記杭の先端部より上方の外周に土砂等が埋め戻されていること、
前記杭の先端面と凹部の底面とは面接触とされ、且つ杭の先端部の外周面と凹部の内周面との間にクリアランスが設けられ、杭底部にせん断力伝達用の隙間材が取り付けられ、前記隙間材の厚さを包含するクリアランスにグリースが充填されていること、
前記杭の軸方向に、同杭の先端面まで貫通された縦孔が設けられ、前記縦孔にグリースが充填されていることを特徴とする、杭先端の浮き上がりを許容した制震構造。Stress supporting concrete is placed on the supporting ground to which the tip of the pile supporting the structure having a large aspect ratio reaches, and a recess for fitting the tip of the pile to the stress transmitting concrete is formed,
The tip of the pile is fitted with the edge cut into the recess, the pile head is rigidly connected to the foundation beam, and earth and sand are backfilled on the outer periphery above the tip of the pile,
The tip end surface of the pile and the bottom surface of the recess are in surface contact, and a clearance is provided between the outer peripheral surface of the tip end of the pile and the inner peripheral surface of the recess, and a gap material for transmitting shear force is provided at the bottom of the pile. It is attached, and the clearance including the thickness of the gap material is filled with grease,
A vibration-damping structure that allows lifting of a pile tip, wherein a vertical hole penetrating to the tip surface of the pile is provided in the axial direction of the pile, and the vertical hole is filled with grease. 応力伝達用コンクリートの凹部に、その内周面及び底面を形成する箱形の鋼製鞘管が設置されていること、
杭の先端部には、その外周面及び先端面を形成する箱形の鋼製鞘管がスタッドを介して一体化されており、杭の内部に設けられた縦孔の先端は前記鋼製鞘管の外側底面まで貫通されていること、
前記鋼製鞘管によって形成された杭の先端部の外周面には、同杭の先端部の外周面と応力伝達用コンクリートの凹部の内周面とのクリアランスに包含される隙間材が取り付けられていることを特徴とする、請求項１に記載した杭先端の浮き上がりを許容した制震構造。A box-shaped steel sheath tube that forms the inner peripheral surface and the bottom surface of the concave portion of the concrete for stress transmission is installed;
A box-shaped steel sheath tube that forms the outer peripheral surface and the tip surface of the pile is integrated with the stud, and the tip of the vertical hole provided in the pile is the steel sheath. Penetrated to the outside bottom of the tube,
A gap material included in the clearance between the outer peripheral surface of the tip of the pile and the inner peripheral surface of the concave portion of the stress transmission concrete is attached to the outer peripheral surface of the pile formed by the steel sheath tube. The seismic response control structure according to claim 1, wherein the pile tip is allowed to lift. 杭の外周であって、応力伝達用コンクリートの略直上の埋め戻し土砂は、杭の外周面と縁を切って打設されたソイルセメントで構成されていることを特徴とする、請求項１又は２に記載した杭先端の浮き上がりを許容した制震構造。The backfill earth and sand which is the outer periphery of the pile and is directly above the stress transmitting concrete is composed of a soil cement casted by cutting off the outer peripheral surface and the edge of the pile. Seismic control structure that allows lifting of the pile tip described in 2. 杭は先細のテーパー形状に形成されていることを特徴とする、請求項１又は２に記載した杭先端の浮き上がりを許容した制震構造。3. The damping structure according to claim 1 or 2, wherein the pile is formed in a tapered taper shape.
JP2002221368A 2002-07-30 2002-07-30 Seismic control structure that allows lifting of pile tip Expired - Fee Related JP3827625B2 (en)

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