JP4111262B2

JP4111262B2 - Connection structure between foundation pile and superstructure, pile head joint, connection method between foundation pile and superstructure

Info

Publication number: JP4111262B2
Application number: JP2002205489A
Authority: JP
Inventors: 隆荒木
Original assignee: Mitani Sekisan Co Ltd
Current assignee: Mitani Sekisan Co Ltd
Priority date: 2002-07-15
Filing date: 2002-07-15
Publication date: 2008-07-02
Anticipated expiration: 2022-07-15
Also published as: JP2004044303A

Description

【０００１】
【発明の属する技術分野】
この発明は、地盤に構築された基礎杭と、その基礎杭の上端部に定着される上部構造物との結合に係る、基礎杭と上部構造物との連結構造、杭頭ジョイント具、基礎杭と上部構造物との連結方法に関する。
【０００２】
【従来の技術】
建築・土木における構造物の基礎杭頭部における結合構造部は、従来から剛結を主に設計されているため、大部分の建築物の基礎杭頭部を基礎に剛結した杭基礎構造が用いられてきた。また、基礎杭の頭部が剛結の場合には、大地震時に発生する大きな曲げ応力により杭頭部分を破損する例が報告されている。
【０００３】
杭頭部の破損を避けるために、ピン結合で杭頭部と基礎とを互いに拘束させない構造による杭基礎構造も提案されてきた（例えば特開2000-220151公報）。
【０００４】
この種の構造は、杭頭部にかかる曲げ応力が防止でき杭頭部の下方の杭本体に作用する曲げ応力も剛結合に比べかなり低減できることが確認されているが、地震時の水平変位が大きくなるため大規模の地震を考慮した場合は、総じて基礎の形状が大きくなると共に滑り面および弾性体材料等で全荷重を常時負担するために材料強度面から使用範囲が限られている。即ち、地震等の無い通常時に支持材料に常時荷重がかかり、実用化に際しては材料の劣化が懸念されているため、材料への荷重を低減せざるを得ず使用範囲が狭かった。
【０００５】
また、鋼製の円形の筒体１１の中に杭本体の各鋼棒９の突出部８を配置し、突出部８の周囲に鉛１０を囲饒して筒体１１との間に介在させ、その筒体１１を基礎７に埋め込ませ水平方向変位を制限し、横揺れエネルギーを吸収する免震構造も提案されている（特開2000- 336666 公報。特に、図１〜５）。この免震構造では、コンパクトではあるが、高鉛直支持力に関する支持構造の点から見た場合耐力的に使用範囲が制限される。
【０００６】
従って、基礎杭と上部構造物との間の基礎において、高鉛直荷重への耐力を有すると共に、高支持力基礎で想定された大地震での高水平力への耐力をも有し、かつ安定した一定の保有耐力に容易に制御され得る結合部が期待されていた。
【０００７】
【発明が解決しようとする課題】
本発明は、杭頭部と上部構造物との結合部において、剛結合の場合に可能な高支持力の伝達機能を保有すると共に、地震時の水平方向変位にもローラー結合の場合同様の機能を有する構造を採用して高耐力を実現すると共に、両者の耐力を所定の値に制御する基礎杭と上部構造との結合構造又は結合方法を提供することを目的としている。
【０００８】
最近、既製杭を利用した高い鉛直支持力（従来比２倍以上）を得ることができる基礎杭構造が開発されつつあり（例えば、特開2002- 97635 公報）、この高い支持力を有する基礎杭構造では、従来より積載荷重の大きい上部構造物の基礎構造に適用されている。従って、高い鉛直支持力に見合った高い曲げモーメントを有する基礎杭が必要であるが、従来から常用されているような上部構造のフーチング内で、基礎杭の杭頭部を剛結合させる方法では大きい地震により杭頭部に水平力が作用し、これに伴い杭頭部に生じる曲げモーメントへの対応が困難であるので、剛接合でありながら大きい曲げモーメントを許容できる結合構造を確実にかつ簡便に実現できる免震構造が必要となってきている。
【０００９】
そこで、従来のように基礎杭の杭頭部から定着用の鉄筋を突出させ、この鉄筋を上部構造に埋設して、この鉄筋が単独で、上部構造全ての曲げモーメントを負担して、基礎杭に伝える構造を見直しする必要がある。例えば、地震時の曲げモーメントに関し定着用の鉄筋が負担する割合を低減させ、その残りの分力をゴムなど弾性材料からなる緩衝材にも負担させる構造が求められている。
【００１０】
【課題を解決するための手段】
然るにこの発明では、定着鋼材と緩衝材を有する杭頭ジョイント具とで、基礎杭の杭頭部と上部構造とを結合し、地震時に、定着用の鉄筋と緩衝材の両方で応力負担をさせることにより高い耐力を有する基礎杭と上部構造の連結構造を実現する。また、この場合、緩衝材を材料自身の弾性領域範囲内の負荷となるように制御することにより、従来のように通常時での過重負荷による緩衝材の劣化も防止でき、前記問題点を解決した。
【００１１】
即ちこの発明は、杭穴内に既製杭を埋設して地中に構築された基礎杭の前記既製杭の中空部を有する上端板に、上下剛板の間に緩衝材を介装してなる杭頭ジョイント具を装着すると共に、定着鋼材の下端部を前記既製杭の上端板のねじ孔に定着固定し、前記定着鋼材の上部を前記杭頭ジョイント具に形成した貫通孔から上方に突出させ、前記緩衝材を押圧した状態を維持して、前記定着鋼材の中間部を前記杭頭ジョイント具に固定し、前記定着鋼材を上部構造物内に定着させたことを特徴とする基礎杭と上部構造物との連結構造である。
【００１２】
また、前記において、前記定着鋼材に螺糸部を形成してナットを螺合して、該ナットを杭頭ジョイント具の上面に配置して締結し、前記杭頭ジョイント具の緩衝材を所定の押圧を維持した状態で、前記定着鋼材を杭頭ジョイント具の上剛板に固定したことを特徴とする基礎杭と上部構造物との連結構造である。また、緩衝材の押圧は、定着鋼材に伝達される上部構造物からの鉛直荷重の内、前記定着鋼材から直接基礎杭に伝達される第一分力と、前記定着鋼材から緩衝材を経由して前記基礎杭に伝達される第二分力とを、前記第二分力が所望の値となるように調節して押圧した基礎杭と上部構造物との連結構造である。
【００１３】
また、前記において、杭頭ジョイント具を、基礎杭に載置する下剛板と、基礎杭の杭頭部を覆う保護筒を有する上剛板を上下に並列し、前記上剛板と前記下剛板との間、前記下剛板と前記保護筒との間に、夫々緩衝材を介装して構成し、前記保護筒の下端部内面と基礎杭の杭頭部外面との間を、弾性材料で塞いだことを特徴とする基礎杭と上部構造物との連結構造である。
【００１４】
また、ジョイント具の発明は、既製杭の中空部を有する上端板の上面に設置できる下剛板と、上剛板とを、緩衝材を挟んで上下に積層してジョイント基材を形成し、前記ジョイント基材に、前記既製杭の上端板のねじ孔に定着される定着鋼材を通すことができる貫通孔を穿設し、前記上剛板に、前記ジョイント基材の外側を覆うことができる保護筒の上端部を固定し、前記保護筒の内面と前記下剛板の外周との間に緩衝材を嵌挿したことを特徴とする杭頭ジョイント具である。
【００１５】
また、前記において、上剛板の外径を下剛板の外径より大径とし、前記上剛板の外周に沿って保護筒の上端部を取り付け、該保護筒を基礎杭の杭頭部より大径に形成したことを特徴とする杭頭ジョイント具である。
【００１６】
また、他の発明は、以下の工程をとることを特徴とした基礎杭と上部構造物との連結方法である。
(1) 杭頭部を露出して、基礎杭を構築する。
(2) 基礎杭の上端部から上方に向けて、下端部を前記基礎杭に定着固定した定着鋼材を突出させる。
(3) 杭頭ジョイント具は、上下方向に貫通孔を設けた垂直方向の緩衝材の外周側に、水平方向の緩衝材を設けてあり、該杭頭ジョイント具の上下方向の貫通孔に、定着鋼材を通しながら、前記基礎杭の上端部に、前記杭頭ジョイント具を装着する。
(4) 前記垂直方向の緩衝材を所定の圧力で、押圧した状態を維持して、前記定着鋼材の中間部を前記杭頭ジョイント具に固定する。
(5) 前記垂直方向の緩衝材の押圧は、前記定着鋼材に伝達される上部構造物からの鉛直荷重の内、前記定着鋼材から直接基礎杭に伝達される第一分力と、前記定着鋼材から垂直方向の緩衝材を経由して前記基礎杭に伝達される第二分力とを、前記第二分力が所望の値となるように調節して押圧する。
(6) 上部構造用のコンクリートを打設して、前記定着鋼材及び杭頭ジョイント具を上部構造物内に定着させる。
【００１７】
前記における基礎杭は、既製杭を使用した杭、現場造成杭のいずれも含む。また、既製杭を使用する場合、杭穴を掘削した後に既製杭を埋設し、あるいは杭穴を掘削せずに、打撃や回転などの方法で既製杭を地盤に押し込み、あるいは杭穴を掘削しつつ既製杭を地盤に押し込める等の従来用いられた工法により構築された基礎杭をいずれも採用できる。
【００１８】
また、前記における定着とは、ねじによる螺合の場合、溶接の場合、鋼材等をコンクリート内に埋設して定着する場合など、構造的に一体となることを指す。
【００１９】
また、前記における定着鋼材は、基礎杭と杭頭ジョイント具とを接合し、上部構造に埋設できれば、その構造は任意である。例えば、基礎杭の構造材料（構造鉄筋等）とは別部材の鋼材を基礎杭の構造材料に溶接等で接合して定着固定する。また、コンクリート系の基礎杭の場合には、別部材の鋼材を、基礎杭に形成した縦穴に嵌挿し、隙間にコンクリート類を充填して定着固定することもできる。また、既製杭を使用した基礎杭の場合には、別部材の鋼材を、既製杭の上端板（構造鉄筋が接合してある）に溶接し、あるいは上端板のねじ孔に螺合して定着固定する。また、定着鋼材を、基礎杭の構造鉄筋を基礎杭の上端部から突出させて構成することもできる。
【００２０】
また、前記における上部構造物とは、基礎杭の杭頭部が定着する基礎杭の上方の構造物を指すが、工程上、フーチングや、最下階のスラブ等が、基礎杭と直接接合される。
【００２１】
また、前記における緩衝材は、例えば、高強度かつ高耐久性を有するウレタンエラストマー、各種ゴム材、ばね材、樹脂コンクリート等を使用する。
【００２２】
【発明の実施の形態】
(1) 下剛板１は、既製杭４２の上端板３８に載置できる円盤状で、貫通孔４、４を形成してある。
上剛板６は、既製杭４２の上端板３８より大径の円盤状で、貫通孔９、９が形成されている。上剛板６の外周７に沿って、保護筒１２の上端部を固定する。
下剛板１と上剛板６との間に、円盤状で、貫通孔１８、１８を有する第一緩衝材１５を介装する。保護筒１２の内面と、下剛板６の外周面及び第一緩衝材１５の外周面との間に、第二緩衝材１９を介装する。以上のようにして、杭頭ジョイント具２２を構成する。ここで、貫通孔４、９、１８は互いに連通し、かつ既製杭４２の上端板３８のねじ孔４０とも連通する。
【００２３】
(2) 既製杭４２の上端板３８上に、杭頭ジョイント具２２を載せる。下剛板１の下面が、上端板３８に当接し、上端板３８のねじ孔４０が、貫通孔４、９、１８と連通し、かつ貫通孔４、９、１８がねじ孔４０より十分大きく形成されている。
貫通孔４、９、１８を通したアンカー筋４９付きの定着鉄筋４４の先端側を、ねじ孔４０に螺合して、定着鉄筋４４の上端側を杭頭ジョイント具２２から上方に突出させる。各定着鉄筋４４にスペーサー４７を挟んで、ナット４８を螺合する。
【００２４】
(3) ナット４８を杭頭ジョイント具２２の上剛板６の上面で、締めると、締めに従って、上下剛板１、６の間が縮み、第一緩衝材１５が押圧される。従って、第一緩衝材１５の弾性変形領域内で、第一緩衝材１５の押圧に対応して、上下剛板１、６に反発力が発生する。対応して、定着鉄筋４４に引張応力を生じさせる。
従って、ナット４８を締めるトルク値を管理することにより、第一緩衝材１５に生じる反発力を管理できる。
【００２５】
(4) 所望のトルク値で、ナット４８の締め付けが完了したならば、アンカー筋４９付きの各定着鉄筋４４等の杭頭部をフーチング５１内に定着させるために、フーチング５１用の型枠、鉄筋５０、５０を組む。型枠内にコンクリートを打設すれば、杭頭ジョイント具２２の上剛板６の上面６ａ、保護筒１２の外面１３ａがコンクリートに接した状態で、ナット４８とその上方の定着鉄筋４４、アンカー筋４９がコンクリート内に埋設される。従って、既製杭４２の杭頭部が、上部構造物を構成するフーチング５１に定着して結合される。
【００２６】
(5) ナット４８のトルク値の管理は、第一緩衝材１５が負担する範囲が、４０〜６０％となるように、この範囲で適宜選択して適用すれば、応力バランス上、好ましい。
【００２７】
【実施例１】
図１〜３に基づきこの発明の実施例を説明する。
【００２８】
［１］杭頭ジョイント具２２の構成
【００２９】
(1) 使用する既製杭４２の上端板３８に載置できる形状で、上端板３８のねじ孔４０、４０に連通して、かつねじ孔４０より大径の貫通孔４、４を形成して、下剛板１とする。下剛板１は円盤状に形成され、外周２は、上端板３８と同程度の外径に形成する。
【００３０】
使用する上端板３８より大径、即ち下剛板１より大径の円盤状で、下剛板１の貫通孔４、４と同一径で連通する貫通孔９、９を形成して、上剛板６を構成する。上剛板６の下面６ｂに、外周７に沿った環状の切欠き１０を形成し、鋼材から形成した保護筒１２の上端部を、切欠き１０に嵌合固着する。
【００３１】
下剛板１と同一平面形状の第一緩衝材１５を形成する。即ち、第一緩衝材１５は、円盤状で、貫通孔４、４と同一位置に同径の貫通孔１８、１８を形成してある。上剛板６と下剛板１との間に、第一緩衝材１５を重ねる。
【００３２】
下剛板１及び第一緩衝材１５の外周２と保護筒１２の内面１３との間に、高さの低い筒状の第二緩衝材１９を嵌挿する。第二緩衝材１９の上面２０は、上剛板１の下面１ａの外周２側に接着され、第二緩衝材１９の下面２０ａは、下剛板１の下面１ｂと面一に形成されている。即ち、第二緩衝材１９の高さは、下剛板１と第一緩衝材１５とを重ねた状態の高さと同一に形成されている。
【００３３】
この状態で、保護筒１２は、下剛板１の下面１ｂから高さＨ_１だけ下方に突出している。また、保護筒１２の内面１３の下端部に、既製杭４２に嵌装するゴムリング４６が当接できるようになっている。
【００３４】
以上のようにして、杭頭ジョイント具２２を構成する（図１）。前記における貫通孔４、９、１８は、定着鉄筋４４が余裕を持って通過できる程度に十分な大きさに形成される。尚、上下剛板１、６、保護筒１２、緩衝材１５、１９の各部材の当接面の全部又は一部で、互いに接着することもできる。
【００３５】
(2) 尚、前記において、第一緩衝材１５、第二緩衝材１９は、２部材から形成したので、異なる材料から構成して、垂直方向、水平方向の求める反発力に対応させることができるが、一つの材料から一体に成型して形成することもできる。
【００３６】
［２］基礎杭４３の構築
【００３７】
(1) 埋設予定の既製杭４２の節状の突起３３の外径より若干大きい掘削径Ｄ_００の杭穴２４を、地盤２８の地表面から所定深度まで掘削し、杭穴２４の下端部に杭穴２４の軸部２４ａの径Ｄ_００の１．５〜２．５倍の掘削径Ｄ_１１で、拡径部長約２．５ｍの拡底根固め部２５を造成する。その拡底根固め部２５内に周辺地盤強度より固化強度の大きなソイルセメント層５５を形成する。また、杭穴２４の軸部２４ａにも周辺地盤強度より固化強度の大きく、かつ拡大根固め部２５のソイルセメント層５５よりも固化強度が小さなソイルセメント層５６を、杭穴口２７の近傍まで形成する（図５（ａ））。
【００３８】
(2) 引続き、下杭の下端部の軸部３２を上部の軸部３１（径Ｄ_０）に比べて細径Ｄ_１の細径部３２として、細径部３２に節状の突起３３、３３を複数有するコンクリート製の下杭（既製杭）３０を形成して、下杭３０を杭穴口２７から杭穴２４内に沈設する（図５（ｂ））。下杭３０に、下杭３０の軸部３１と同径の軸部３７を有するストレート状のコンクリート製の上杭（既製杭）３６を接合して（図５（ｃ））、既製杭４２として、既製杭４２（下杭３０）の突起３３、３３を高固化強度のソイルセメントが充填された拡底根固め部２５のソイルセメント層５５内に設置する（図５（ｄ））。
【００３９】
下杭３６は、軸部３１から下端部の細径部３２に変化する部分に、上側の突起３３を配置し、該部を大径調節部３３ａとする。大径調節部３３ａは、拡大根固め部２５の上端２５ａから深さＤＨ_２だけ、拡大根固め部２５内に入った状態で埋設され、既製杭４２の下面３４（下杭３０の下面）と杭穴２４の底２６（拡大根固め部の底）とに深さＤＨ_１だけ間隙を設け、所要の固化強度を確保している。
【００４０】
(3) 以上のように、杭穴２４内に既製杭４２を埋設して、基礎杭４３を構成する（図５（ｄ））。
【００４１】
(4) このように形成した拡大根固め部２５内の既製杭４２（下杭３０）は、鉛直荷重に対して、その突起３３や下面３４から斜め下方に拡大根固め部の底２６（杭穴２４の底２６）に向けて、ソイルセメント層５５内をせん断力が伝搬し、引抜力に対しては、突起３３、３３から斜め上方に向けて、ソイルセメント層５５内をせん断力が伝搬する。
【００４２】
また、上杭３６は、下杭３０の軸部３１と同径として、杭材の曲げモーメントを増強した構成とし、既製杭４２の杭頭部で地震時等に発生する水平荷重に対して十分耐える構造となっている。
【００４３】
従って、杭穴２４内に埋設した既製杭４２は、杭穴根固め部２５内で、せん断力を充分発現させ、高支持力を有すると共に、杭頭部での水平耐力を高めた基礎杭を造成する。
【００４４】
(5) 既製杭４２の地盤２８（杭穴２４）内への埋設は、杭穴２４を掘削した後の埋設に限らず、従来の他の方法を採用することもできる。即ち、杭穴２４を掘削せずに、打撃や回転などの方法で既製杭４２を地盤２８に押し込み、あるいは杭穴２４を掘削しつつ既製杭４２を地盤２８に押し込める中掘工法とすることもできる。
【００４５】
［３］上部構造物（フーチング５１）の構築
【００４６】
(1) 上杭３６には、ねじ孔４０を有する上端板３８を取り付けてあり、上端板３８を地盤２８より上方に露出させる（図５（ｄ）、図１）。地盤２８上に砂利層５８を形成する。
【００４７】
(2) 既製杭４２（上杭３６）の上端板３８の各ねじ孔４０に、外側に螺糸を形成した定着鉄筋４４、４４の下端部を捻じ込み固定する。また、事前に、既製杭４２（上杭３６）の杭頭部にゴムリング４６を嵌装する（図１）。
【００４８】
続いて、下剛板１の各貫通孔４、４に、定着鉄筋４４を通して、下剛板１を上端板３８に載置する。
【００４９】
続いて、予め第一緩衝材１５の外周に、第二緩衝材１９を貼りあわせた連結緩衝材２１を、その各貫通孔１８、１８に、夫々定着鉄筋４４を通しながら、連結緩衝材２１の第一緩衝材１５を下剛板１に載置し、第二緩衝材１９の下端部を、下剛板１の外周２に嵌装する。
【００５０】
続いて、予め上剛板６の環状の切欠き１０に、保護筒１２の上端部を嵌装して溶接固着し、保護筒１２付きの上剛板６を吊り下ろし、上剛板６の各貫通孔９、９に定着鉄筋４４を夫々通すと共に、上剛板６を結合緩衝材２１上に載置する。この際、保護筒１２は、上部が結合緩衝材２１の第二緩衝材１９に嵌装し、内面１３の下端部にゴムリング４６が弾性支持して、間隙が塞がれる。
【００５１】
この状態で、上剛板６の上面６ａから定着鉄筋４４、４４が突出しており、各定着鉄筋４４、４４に、上からスペーサ（座金）４７をはめ、ナット４８を螺合する。ナット４８を締めながら、上剛板６と下剛板１とで、結合緩衝材２１を押圧してこれを縮め、所定トルク値まで締め付け、ナット４８と定着させる。
【００５２】
(3) 各定着鉄筋４４、４４の上端には、フーチング５１と既製杭４２とを定着する為のアンカー筋４９が一体に形成されている（図３、図４）。通常、定着鉄筋４４とアンカー筋４９を一体の鋼材から成形加工する。
【００５３】
アンカー筋４９の固着作業に前後して、砂利層５８上に、均しコンクリート層５９を形成する。保護筒１２の下端部を均しコンクリート層５９内に埋設し、均しコンクリート層５９を既製杭４２の側面まで至らせる。一般に均しコンクリート層５９は薄く、静かにコンクリートが打設されるので、コンクリートが保護筒１２の上方へ入るおそれはなく、更に、ゴムリング４６が弾性当接しているので、コンクリートが保護筒１２の上方へ入ることを確実に防止できる。
【００５４】
(4) 均しコンクリート層５９上で、上剛板６、保護筒１２の外周側に、上部構造物のフーチング用の鉄筋５０、５０を配筋して、必要ならばアンカー鉄筋４９、４９と結合し、また、フーチング用の型枠を構築し（図示していない）、型枠内に、コンクリートを打設する。
【００５５】
(5) コンクリートが固化発現した後に、杭穴２４内に埋設された既製杭４２からなる基礎杭４３とフーチング５１とが結合される。
【００５６】
［４］応力の伝達作用の説明
【００５７】
(1) 長期荷重の作用時（鉛直荷重のみが作用する通常時）
【００５８】
上部構造物の荷重は、フーチング５１で受け、杭頭ジョイント２２の全体を介して既製杭４２に伝達され基礎杭４３で負担されるようになっている。
【００５９】
一方、所定のトルク値でナット４８を締め付けてあるので、そのトルク値の大小に対応して第一緩衝材１５に反発力を生じさせ荷重の一部を負担させている。この第一緩衝材の締め付けは、第一緩衝材１５の弾性変形内で調整されている（図６（ａ）（ｂ））。
【００６０】
(2) 水平荷重の作用時（地震等の短期時）
【００６１】
地震等で杭頭部に水平力（水平荷重）が作用した時には、その既製杭４２の杭頭部に曲げモーメントが生じ、上剛板６と下剛板１とがずれるように作用する。具体的には、上剛板６の一側が上がり、他側が下がるような変化が生じ、この変化は先ず、第一緩衝材１５及び第二緩衝材１９の変形（弾性応力）で吸収され（図６（ｃ））、更に大きい曲げモーメントが生じた場合には、第一第二緩衝材１５、１９での応力吸収に加えて、剛結合の定着鉄筋４４の伸張等による変形による耐力で吸収される構造となっている。この場合も第一第二緩衝材１５、１９は弾性変形内で変形に追随するよう維持されている。
【００６２】
また、既製杭４２の杭頭部が移動した際に、既製杭４２の外面と保護筒１２の内面との距離が短くなる部分が生じるが、このずれはゴムリング４６でも吸収し、既製杭４２や保護筒１２を損傷しないようにしている。
【００６３】
また、定着鉄筋４４の軸径に対して、上下剛板６、１の貫通孔９、４は充分に大径に形成し、既製杭４２の杭頭部の変位に伴い定着鉄筋４４をこの径の隙間の範囲内で移動させ損傷・変形を低減させるようにしている。
【００６４】
［５］他の実施例
【００６５】
(1) 前記実施例において、既製杭４２の杭頭部に下剛板１、結合緩衝材２１、上剛板６を順に載せて、杭頭ジョイント具２２を形成したが、予め杭頭ジョイント具２２を形成しておき、上端板３８に定着した定着鉄筋４４に、杭頭ジョイント具２２の貫通孔４、９、１８を挿通しながら、杭頭ジョイント具２２を既製杭４２の上端板３８に載置することもできる。
【００６６】
(2) また、前記実施例において、既製杭４２の上端板３８のねじ孔４０に定着鉄筋４４を螺合した後に、杭頭ジョイント具（上下剛板６、１、緩衝材１５、１９）２２を取り付けたが、先に杭頭ジョイント具２２を既製杭４２の上端板３８に載せた後に、杭頭ジョイント具２２の貫通孔９、１８、４を通過させて、定着鉄筋４４の下端部をねじ孔４０に螺合することもできる。
【００６７】
(3) また、前記実施例において、定着鉄筋４４とアンカー筋４９を一体の鋼材から成形加工したが、別々に製造した定着鉄筋４４とアンカー筋４９とを溶接等により一体に接合して形成することもできる。尚、この場合には、接合強度に関するの信頼性等の為、現場溶接ではなく工場で溶接することが望ましい。
【００６８】
(4) また、前記(3)のように定着鉄筋４４とアンカー筋４９とを分離して形成した場合、アンカー筋４９を定着鉄筋４４に固着する代わりに、あるいは定着鉄筋４４に固着して、更にアンカー筋４９を上剛板６に固着することもできる（図示していない）。尚、定着鉄筋４４とアンカー筋４９を一体に形成した場合であっても、更に、別のアンカー筋４９を上剛板６に固着することもできる（図示していない）。
【００６９】
(5) また、前記実施例において、定着鉄筋４４は、既製杭４２の上端板３８に螺合して、既製杭４２に定着させたが、上端板３８に溶接し、あるいは上端板３８に螺合して更に溶接して、定着させることもできる。
【００７０】
(6) また、前記実施例において、保護筒１２の下端部は、均しコンクリート層５９内に埋設したので、保護筒１２内にコンクリートが入り込むことを確実に防止できるので好ましいが、直接にフーチング５１内に埋設することもできる（図示していない）。
【００７１】
(7) 杭頭ジョイント具２２は、基礎杭４３の構築が完了した後に、基礎杭４３に装着したが、既製杭４２を使用して基礎杭４３を構成する場合には、予め既製杭４２の上端板に、杭頭ジョイント具２２を取り付けた状態で、既製杭４２を杭穴２４内に埋設することもできる（図示していない）。
【００７２】
【発明の効果】
(1) この発明では、定着鋼材の下部を基礎杭に定着固定し、中間部を、緩衝材を弾性を維持する範囲で、押圧した杭頭ジョイント具に固定し、上端部を上部構造内に定着させたので、通常時の上部構造物の鉛直荷重は、定着鋼材及び杭頭ジョイント具の緩衝材を介して、基礎杭に伝達される。この際、緩衝材の押圧力に応じて、緩衝材が負担すべき鉛直荷重の分量が決まり、定着鋼材が負担すべき鉛直荷重の分量を軽減できる。
【００７３】
従って、高支持力杭では、１本当たりの基礎杭が負担すべき支持力を大きうできるが、これに伴い、１本が負担すべき鉛直荷重が大きく設定されるが、この倍であっても、対応する定着鋼材をより耐力の大きな材料を選択したり、あるいは定着鋼材の本数を軽減できる。
【００７４】
(2) 従って、上部構造物と基礎杭を結合した際に、従来から剛結合が常用されて来たため、特に高い鉛直支持力を発揮できる基礎杭においては、地震等での水平力による水平変位を上部構造に伝達してしまうため、基礎杭の杭耐力が充分に活かされ難いという問題があったが、本発明の上部構造物と基礎杭との結合構造では、剛結合される定着鋼材と緩衝材とを併用して曲げモーメントの負荷を分散し、定着鋼材の負担を低減したので、高い支持力を有す基礎杭においても鉛直、水平両荷重に対してバランスの取れた高耐力を有する構造を容易に提供できる。
【００７５】
また、剛結合部分と緩衝材とをボルトとナットによる締め付けで固定した場合には、従来から提案されている特殊な積層ゴムやダンパ類で全荷重を支持した各種の免震構造に比較し、容易に免震構造を実現できると共に、緩衝材をその弾性範囲内で制御して使用できるので、通常の長期荷重時における緩衝材の劣化も防止できる。
従って、使用する緩衝材の選択範囲を広くできる。
【００７６】
(3) また、定着鋼材に螺糸部を形成してナットを螺合して、ナットを杭頭ジョイント具の上面に配置して締結する場合には、ナットの締め付けトルク値を管理することにより、地震等の水平荷重が作用する時の緩衝材の加圧力、ひいては定着鋼材が負担すべき、曲げモーメントを管理できる。従って、所望の緩衝材の加圧力や定着鋼材の圧縮応力を容易に設定できる効果がある。
【００７７】
また、トルク値で管理するので、トルク値と緩衝材の加圧力との相関関係も容易に解析でき、トルクレンチなどを使用すれば、現場での所望のトルク値の管理が容易である。
【００７８】
また、既製杭、杭頭ジョイント具の結合作業が容易になる。
【００７９】
また、定着鋼材の下端側にも螺糸部を形成すれば、既製杭を使用した場合、その上端板に形成されている螺孔を使用して、容易に定着鋼材と定着固定できる。
【００８０】
(4) また、基礎杭の杭頭部より大径の保護筒を使用して杭頭ジョイント具を構成した場合には、水平荷重の付加に伴う杭頭部及び緩衝材の移動スペースを確保して、杭頭部及び上部構造の破損を防止できる範囲を広げることができる。
【００８１】
またこの場合、杭頭部と保護筒の間に弾性材料を嵌挿すれば、更に破損を防止出きると共に、弾性力により杭頭部が移動後に現状復帰することを促すことができる。更に、上部構造のコンクリートを打設する際に、保護筒の内側にコンクリートが入ることを防止できる。
【図面の簡単な説明】
【図１】この発明の実施例の部材の構成を表す左側を破切した正面図である。
【図２】図１のＡ−Ａ線における断面図である。
【図３】同じく構築した状態の左側を破切した正面図である。
【図４】同じく構築した状態の左側を破切した正面図である。
【図５】（ａ）〜（ｄ）は、この発明の実施に使用する基礎杭を構築する過程を説明する縦断面図である。
【図６】この発明の緩衝材の変形を表す概念図で、（ａ）は締め付け前、（ｂ）長期荷重時、（ｃ）短期荷重で曲げモーメントが作用した状態、を夫々表す。
【符号の説明】
１下剛板
２下剛板の外周
４下剛板の貫通孔
６上剛板
７上剛板の外周
９上剛板の貫通孔
１０上剛板の切欠き
１２保護筒
１３保護筒の内面
１３ａ保護筒の外面
１５第一緩衝材
１６第一緩衝材の外周
１８第一緩衝材の貫通孔
１９第二緩衝材
２０第二緩衝材の上面
２０ａ第二緩衝材の下面
２１結合緩衝材
２２杭頭ジョイント具
２４杭穴
２４ａ杭穴の軸部
２５杭穴の拡底根固め部
２８地盤
３０下杭（既製杭）
３６上杭（既製杭）
３８上端板
３９上端板の中空部
４０上端板のねじ孔
４２既製杭
４３基礎杭
４４定着鉄筋
４６ゴムリング
４７スペーサー
４８ナット
４９アンカー筋
５０フーチング用の鉄筋
５１フーチング
５３基礎杭構造
５５、５６ソイルセメント層
５９均しコンクリート層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a connection structure between a foundation pile and an upper structure, a pile head joint tool, and a foundation pile, which are related to the connection between the foundation pile built on the ground and the upper structure fixed to the upper end of the foundation pile. The present invention relates to a method for connecting the upper structure to the upper structure.
[0002]
[Prior art]
Since the joint structure in the foundation pile head of structures in civil engineering and civil engineering has been mainly designed to be rigidly connected, the pile foundation structure that is rigidly connected to the foundation pile head of most buildings is used. Has been used. Moreover, when the head of a foundation pile is rigidly connected, the example which damages a pile head part by the big bending stress which generate | occur | produces at the time of a big earthquake is reported.
[0003]
In order to avoid damage to the pile head, a pile foundation structure having a structure in which the pile head and the foundation are not restrained by pin connection has also been proposed (for example, JP 2000-220151 A).
[0004]
This type of structure has been confirmed to be able to prevent bending stress on the pile head and significantly reduce the bending stress acting on the pile body below the pile head as compared to rigid coupling. When large-scale earthquakes are taken into consideration, the shape of the foundation is generally large, and the entire range of use is limited in terms of material strength because the entire load is always borne by the sliding surface and elastic material. That is, since a load is always applied to the support material at normal times without an earthquake or the like, and there is a concern about deterioration of the material at the time of practical use, the load on the material has to be reduced, and the use range is narrow.
[0005]
Further, the protruding portions 8 of the steel rods 9 of the pile main body are arranged in a steel circular cylindrical body 11, and the lead 10 is surrounded around the protruding portion 8 so as to be interposed between the cylindrical body 11. A seismic isolation structure has also been proposed in which the cylindrical body 11 is embedded in the foundation 7 to limit horizontal displacement and absorb roll energy (Japanese Patent Laid-Open No. 2000-336666, especially FIGS. 1 to 5). Although this seismic isolation structure is compact, the range of use is limited in terms of strength when viewed in terms of the support structure for high vertical support force.
[0006]
Therefore, in the foundation between the foundation pile and the superstructure, it has the resistance to high vertical load, and also has the resistance to high horizontal force in the case of a large earthquake assumed in the high bearing capacity foundation, and is stable. Therefore, a joint that can be easily controlled to a certain holding strength has been expected.
[0007]
[Problems to be solved by the invention]
The present invention has a function of transmitting a high bearing force that is possible in the case of a rigid connection at the joint between the pile head and the superstructure, and also has the same function in the case of a roller connection for horizontal displacement during an earthquake. It is an object of the present invention to provide a coupling structure or a coupling method of a foundation pile and an upper structure that adopts a structure having a high strength and realizes a high yield strength and controls both the yield strengths to a predetermined value.
[0008]
Recently, foundation pile structures that can obtain high vertical bearing capacity (more than double the conventional one) using off-the-shelf piles are being developed (for example, JP 2002-97635 A). In the structure, it is applied to the foundation structure of the superstructure having a larger load capacity than before. Therefore, a foundation pile having a high bending moment commensurate with a high vertical bearing force is required, but the method of rigidly connecting the pile head of the foundation pile in a superstructure footing that is conventionally used is large. A horizontal force acts on the pile head due to the earthquake, and it is difficult to cope with the bending moment generated at the pile head. A seismic isolation structure that can be realized is needed.
[0009]
Therefore, as in the conventional case, the reinforcing bar protrudes from the pile head of the foundation pile, and this reinforcing bar is embedded in the upper structure, and this reinforcing bar alone bears the bending moment of the entire upper structure. It is necessary to review the structure to convey to. For example, there is a demand for a structure that reduces the proportion of the bending rebars that are borne by the anchoring rebars and that the remaining component force is also borne by an elastic material such as rubber.
[0010]
[Means for Solving the Problems]
However, in this invention, the pile head joint and the upper structure of the foundation pile are combined with the pile head joint tool having the fixing steel material and the buffer material, and the stress load is applied to both the fixing reinforcing bar and the buffer material in the event of an earthquake. In this way, a foundation pile with high strength and a superstructure are realized. In this case, the cushioning material becomes a load within the elastic region range of the material itself. Ruyo By controlling in this way, it is possible to prevent the buffer material from being deteriorated due to an overload in a normal state as in the prior art, and the above-mentioned problems have been solved.
[0011]
That is, this invention A ready-made pile is buried in the pile hole Of foundation piles built underground Upper end plate having a hollow portion of the ready-made pile In addition, Between upper and lower rigid plates Attach a pile head joint device with cushioning material and end Part To the screw hole of the upper end plate of the ready-made pile Fixing and fixing Said The upper part of the fixing steel material is protruded upward from the through hole formed in the pile head joint device, the state of pressing the buffer material is maintained, and the intermediate portion of the fixing steel material is fixed to the pile head joint device, This is a connection structure between a foundation pile and an upper structure, characterized in that a fixing steel material is fixed in the upper structure.
[0012]
Further, in the above, a threaded portion is formed in the fixing steel material, a nut is screwed together, the nut is arranged and fastened on the upper surface of the pile head joint tool, and the cushioning material of the pile head joint tool is set to a predetermined value. In the state where the pressure is maintained, the fixing steel material is connected to the pile head joint tool. Upper rigid board It is the connection structure of the foundation pile and the superstructure characterized by being fixed to. In addition, the vertical pressure from the upper structure transmitted to the fixing steel material is the first component force transmitted directly from the fixing steel material to the foundation pile, and the pressing force of the buffer material is transmitted from the fixing steel material to the fixing material. The second component force transmitted to the foundation pile is adjusted to press the second component force so that the second component force has a desired value.
[0013]
Further, in the above, the pile head joint device is arranged in parallel with a lower rigid plate placed on the foundation pile and an upper rigid plate having a protective cylinder covering the pile head of the foundation pile, and the upper rigid plate and the lower Between the rigid plate, between the lower rigid plate and the protective cylinder, each configured with a cushioning material, between the lower end inner surface of the protective cylinder and the pile head outer surface of the foundation pile, It is a connection structure between the foundation pile and the superstructure, which is characterized by being covered with an elastic material.
[0014]
The invention of the joint tool Upper end plate with hollow part of ready-made pile A lower base plate and an upper base plate that can be installed on the upper surface of the upper and lower layers are laminated vertically with a cushioning material in between to form a joint base material. Screw holes in the top plate of ready-made piles Settled in Fixing A through hole through which a steel material can be passed is formed, and an upper end portion of a protective cylinder capable of covering the outside of the joint base is fixed to the upper rigid plate, and an inner surface of the protective cylinder Said It is a pile head joint tool characterized by inserting a buffer material between the outer periphery of the lower rigid plate.
[0015]
In the above, the outer diameter of the upper rigid plate is larger than the outer diameter of the lower rigid plate, the upper end of the protective cylinder is attached along the outer periphery of the upper rigid plate, and the protective cylinder is attached to the pile head of the foundation pile It is a pile head joint tool characterized by having formed in larger diameter.
[0016]
Moreover, another invention is the connection method of the foundation pile and superstructure characterized by taking the following processes.
(1) Expose the pile head and build the foundation pile.
(2) From the upper end of the foundation pile, the fixed steel material with the lower end fixed and fixed to the foundation pile is protruded upward.
(3) The pile head joint tool is provided with a horizontal cushioning material on the outer peripheral side of the vertical cushioning material having through holes in the vertical direction, While passing the fixing steel material through the vertical through hole of the pile head joint tool, on the upper end of the foundation pile, Said Install the pile head joint tool.
(4) said Vertical A state in which the buffer material is pressed at a predetermined pressure is maintained, and an intermediate portion of the fixing steel material is fixed to the pile head joint device.
(5) said Vertical Among the vertical loads from the upper structure transmitted to the fixing steel material, the buffer material is pressed from a first component force transmitted directly from the fixing steel material to the foundation pile, and from the fixing steel material. Vertical The second component force transmitted to the foundation pile via the cushioning material is adjusted and pressed so that the second component force becomes a desired value.
(6) Placing concrete for superstructure to fix the fixing steel and pile head joints in the superstructure.
[0017]
The foundation pile in the above includes both a pile using a ready-made pile and a field-built pile. In addition, when using ready-made piles, after excavating the pile holes, bury the ready-made piles, or without digging the pile holes, push the ready-made piles into the ground by means of striking or rotating, or excavating the pile holes. However, any foundation pile constructed by a conventionally used method such as pushing an already-made pile into the ground can be adopted.
[0018]
In addition, the fixing in the above means that they are structurally integrated, for example, in the case of screwing with screws, in the case of welding, or in the case of fixing by embedding steel or the like in concrete.
[0019]
Moreover, the fixing steel material in the above will be arbitrary if the foundation pile and a pile head joint tool are joined and it can embed in an upper structure. For example, a steel material that is a separate member from the structural material of the foundation pile (such as structural reinforcing bars) is joined and fixed to the structural material of the foundation pile by welding or the like. In the case of a concrete-based foundation pile, a steel member as a separate member can be inserted into a vertical hole formed in the foundation pile, and concrete can be filled in the gap and fixed. Also, in the case of foundation piles using ready-made piles, the steel material of another member is welded to the upper end plate of the pre-made pile (with structural rebars joined), or screwed into the screw hole of the upper end plate and fixed. Fix it. In addition, the fixing steel material can be configured by projecting the structural reinforcement of the foundation pile from the upper end of the foundation pile.
[0020]
The upper structure in the above refers to the structure above the foundation pile where the pile head of the foundation pile is fixed, but in the process, the footing, the slab on the lowest floor, etc. are directly joined to the foundation pile. The
[0021]
Further, as the cushioning material, for example, urethane elastomer having high strength and high durability, various rubber materials, spring materials, resin concrete, and the like are used.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
(1) The lower rigid plate 1 has a disk shape that can be placed on the upper end plate 38 of the ready-made pile 42 and has through holes 4 and 4 formed therein.
The upper rigid plate 6 has a disk shape larger in diameter than the upper end plate 38 of the ready-made pile 42 and has through holes 9 and 9 formed therein. The upper end portion of the protective cylinder 12 is fixed along the outer periphery 7 of the upper rigid plate 6.
Between the lower rigid plate 1 and the upper rigid plate 6, a first cushioning material 15 having a disk shape and having through holes 18 and 18 is interposed. A second cushioning material 19 is interposed between the inner surface of the protective cylinder 12 and the outer circumferential surface of the lower rigid plate 6 and the outer circumferential surface of the first cushioning material 15. The pile head joint tool 22 is comprised as mentioned above. Here, the through holes 4, 9 and 18 communicate with each other and also with the screw holes 40 of the upper end plate 38 of the ready-made pile 42.
[0023]
(2) The pile head joint tool 22 is placed on the upper end plate 38 of the ready-made pile 42. The lower surface of the lower rigid plate 1 contacts the upper end plate 38, the screw hole 40 of the upper end plate 38 communicates with the through holes 4, 9, 18, and the through holes 4, 9, 18 are sufficiently larger than the screw hole 40. Is formed.
The tip end side of the fixing reinforcing bar 44 with the anchor bar 49 passing through the through holes 4, 9, 18 is screwed into the screw hole 40, and the upper end side of the fixing reinforcing bar 44 protrudes upward from the pile head joint tool 22. A nut 48 is screwed together with a spacer 47 sandwiched between the fixing reinforcing bars 44.
[0024]
(3) When the nut 48 is tightened on the upper surface of the upper rigid plate 6 of the pile head joint tool 22, the space between the upper and lower rigid plates 1, 6 is contracted and the first cushioning material 15 is pressed according to the tightening. Accordingly, a repulsive force is generated in the upper and lower rigid plates 1 and 6 in response to the pressing of the first buffer material 15 within the elastic deformation region of the first buffer material 15. Correspondingly, tensile stress is generated in the fixing rebar 44.
Therefore, the repulsive force generated in the first cushioning material 15 can be managed by managing the torque value for tightening the nut 48.
[0025]
(4) When the tightening of the nut 48 is completed with a desired torque value, in order to fix the pile heads such as the fixing reinforcing bars 44 with the anchor bars 49 in the footing 51, a formwork for the footing 51, Assemble the reinforcing bars 50 and 50. If concrete is placed in the formwork, the nut 48 and the fixing rebar 44 above the nut 48 and the anchor in the state where the upper surface 6a of the upper rigid plate 6 of the pile head joint tool 22 and the outer surface 13a of the protective cylinder 12 are in contact with the concrete. A streak 49 is embedded in the concrete. Therefore, the pile head of the ready-made pile 42 is fixed and coupled to the footing 51 constituting the upper structure.
[0026]
(5) The management of the torque value of the nut 48 is preferable in terms of stress balance if it is appropriately selected and applied within this range so that the range borne by the first buffer material 15 is 40 to 60%.
[0027]
[Example 1]
An embodiment of the present invention will be described with reference to FIGS.
[0028]
[1] Configuration of pile head joint tool 22
[0029]
(1) Forming through-holes 4 and 4 having a shape that can be placed on the upper end plate 38 of the ready-made pile 42 to be used, communicating with the screw holes 40 and 40 of the upper end plate 38 and having a larger diameter than the screw hole 40. The lower rigid plate 1 is assumed. The lower rigid plate 1 is formed in a disc shape, and the outer periphery 2 is formed to have an outer diameter comparable to that of the upper end plate 38.
[0030]
A through hole 9, 9 having a diameter larger than that of the upper end plate 38 to be used, that is, a diameter larger than that of the lower rigid plate 1 and having the same diameter as the through holes 4, 4 of the lower rigid plate 1 is formed. The plate 6 is configured. An annular notch 10 along the outer periphery 7 is formed on the lower surface 6 b of the upper rigid plate 6, and the upper end portion of the protective cylinder 12 made of steel is fitted and fixed to the notch 10.
[0031]
A first cushioning material 15 having the same planar shape as the lower rigid plate 1 is formed. That is, the first buffer material 15 has a disk shape and has through holes 18 and 18 having the same diameter at the same positions as the through holes 4 and 4. A first cushioning material 15 is placed between the upper rigid plate 6 and the lower rigid plate 1.
[0032]
A cylindrical second cushioning material 19 having a low height is inserted between the outer periphery 2 of the lower rigid plate 1 and the first cushioning material 15 and the inner surface 13 of the protective cylinder 12. The upper surface 20 of the second cushioning material 19 is bonded to the outer periphery 2 side of the lower surface 1 a of the upper rigid plate 1, and the lower surface 20 a of the second cushioning material 19 is formed flush with the lower surface 1 b of the lower rigid plate 1. . That is, the height of the second cushioning material 19 is the same as the height of the state in which the lower rigid plate 1 and the first cushioning material 15 are overlapped.
[0033]
In this state, the protective cylinder 12 has a height H from the lower surface 1b of the lower rigid plate 1. ₁ Only protrudes downward. Further, a rubber ring 46 fitted to the ready-made pile 42 can be brought into contact with the lower end portion of the inner surface 13 of the protective cylinder 12.
[0034]
The pile head joint tool 22 is comprised as mentioned above (FIG. 1). The through holes 4, 9, and 18 are formed with a sufficient size so that the fixing reinforcing bar 44 can pass with a margin. The upper and lower rigid plates 1 and 6, the protective cylinder 12, and the cushioning materials 15 and 19 may be bonded to each other at all or part of the contact surfaces.
[0035]
(2) In the above, since the first cushioning material 15 and the second cushioning material 19 are formed of two members, they can be made of different materials and correspond to the repulsive forces required in the vertical and horizontal directions. However, it can also be formed by integrally molding from one material.
[0036]
[2] Construction of foundation pile 43
[0037]
(1) Excavation diameter D slightly larger than the outer diameter of the node-like protrusion 33 of the ready-made pile 42 to be buried ₀₀ The pile hole 24 is excavated from the ground surface of the ground 28 to a predetermined depth, and the diameter D of the shaft portion 24a of the pile hole 24 is formed at the lower end of the pile hole 24. ₀₀ Drilling diameter D of 1.5 to 2.5 times ₁₁ Thus, an expanded bottom hardening part 25 having an enlarged diameter part length of about 2.5 m is formed. A soil cement layer 55 having a larger solidification strength than the surrounding ground strength is formed in the expanded bottom hardening portion 25. In addition, a soil cement layer 56 having a solidification strength larger than the surrounding ground strength and a smaller solidification strength than the soil cement layer 55 of the expanded root consolidation portion 25 is also formed in the vicinity of the pile hole mouth 27 at the shaft portion 24a of the pile hole 24. (FIG. 5A).
[0038]
(2) The shaft portion 32 at the lower end of the lower pile is continuously replaced with the upper shaft portion 31 (diameter D ₀ Small diameter D compared to ₁ As the small diameter portion 32, a concrete lower pile (ready pile) 30 having a plurality of node-like protrusions 33, 33 is formed on the small diameter portion 32, and the lower pile 30 is moved from the pile hole port 27 into the pile hole 24. It is installed (FIG. 5B). A straight concrete upper pile (ready-made pile) 36 having a shaft portion 37 having the same diameter as the shaft portion 31 of the lower pile 30 is joined to the lower pile 30 (FIG. 5C), and a ready-made pile 42 is obtained. Then, the projections 33 and 33 of the ready-made pile 42 (lower pile 30) are installed in the soil cement layer 55 of the bottomed root consolidation portion 25 filled with the soil cement having a high solidification strength (FIG. 5D).
[0039]
In the lower pile 36, an upper protrusion 33 is arranged at a portion that changes from the shaft portion 31 to the small-diameter portion 32 at the lower end portion, and this portion serves as a large-diameter adjusting portion 33a. The large-diameter adjusting portion 33a has a depth DH from the upper end 25a of the enlarged root hardening portion 25. ₂ The depth DH is embedded in the state of entering the enlarged root consolidation portion 25, and is formed on the bottom surface 34 of the ready-made pile 42 (the bottom surface of the lower pile 30) and the bottom 26 of the pile hole 24 (the bottom of the expansion root consolidation portion). ₁ Only the gap is provided to ensure the required solidification strength.
[0040]
(3) As mentioned above, the ready-made pile 42 is embed | buried in the pile hole 24, and the foundation pile 43 is comprised (FIG.5 (d)).
[0041]
(4) The ready-made pile 42 (lower pile 30) in the enlarged root consolidation part 25 formed in this way is the bottom 26 (pile of the enlarged root consolidation part obliquely downward from the protrusion 33 and the lower surface 34 with respect to the vertical load. The shear force propagates in the soil cement layer 55 toward the bottom 26) of the hole 24, and the shear force propagates in the soil cement layer 55 obliquely upward from the protrusions 33 and 33 with respect to the pulling force. To do.
[0042]
In addition, the upper pile 36 has the same diameter as the shaft portion 31 of the lower pile 30 and has a configuration in which the bending moment of the pile material is increased, which is sufficient for a horizontal load generated during an earthquake at the pile head of the ready-made pile 42. It has a structure to withstand.
[0043]
Therefore, the ready-made pile 42 embedded in the pile hole 24 is a foundation pile having a sufficient bearing force and a high bearing capacity in the pile hole consolidation part 25 and having a high horizontal strength at the pile head. Create.
[0044]
(Five) The embedding of the ready-made pile 42 in the ground 28 (pile hole 24) is not limited to the embedding after the pile hole 24 is excavated, and other conventional methods can also be adopted. That is, without making the pile hole 24, the ready-made pile 42 may be pushed into the ground 28 by a method such as striking or rotating, or the ready-made pile 42 may be pushed into the ground 28 while excavating the pile hole 24. it can.
[0045]
[3] Construction of superstructure (footing 51)
[0046]
(1) An upper end plate 38 having a screw hole 40 is attached to the upper pile 36, and the upper end plate 38 is exposed above the ground 28 (FIG. 5 (d), FIG. 1). A gravel layer 58 is formed on the ground 28.
[0047]
(2) Screw and fix the lower end portions of the fixing reinforcing bars 44, 44 having threads formed on the outer sides of the screw holes 40 of the upper end plate 38 of the ready-made pile 42 (upper pile 36). Moreover, the rubber ring 46 is fitted in the pile head of the ready-made pile 42 (upper pile 36) beforehand (FIG. 1).
[0048]
Subsequently, the lower rigid plate 1 is placed on the upper end plate 38 through the fixing reinforcing bars 44 through the through holes 4 and 4 of the lower rigid plate 1.
[0049]
Subsequently, the connection buffer material 21 in which the second buffer material 19 is bonded to the outer periphery of the first buffer material 15 in advance is passed through the fixing rebars 44 through the through holes 18 and 18, respectively. The first cushioning material 15 is placed on the lower rigid plate 1, and the lower end portion of the second cushioning material 19 is fitted to the outer periphery 2 of the lower rigid plate 1.
[0050]
Subsequently, the upper end of the protective cylinder 12 is fitted and fixed to the annular notch 10 of the upper rigid plate 6 in advance, and the upper rigid plate 6 with the protective cylinder 12 is suspended. The fixing reinforcing bars 44 are passed through the through holes 9 and 9, respectively, and the upper rigid plate 6 is placed on the coupling buffer material 21. At this time, the upper portion of the protective cylinder 12 is fitted into the second cushioning material 19 of the coupling cushioning material 21, and the rubber ring 46 is elastically supported at the lower end portion of the inner surface 13 to close the gap.
[0051]
In this state, the fixing reinforcing bars 44 and 44 protrude from the upper surface 6a of the upper rigid plate 6. A spacer (washer) 47 is fitted to each fixing reinforcing bar 44 and 44 from above, and a nut 48 is screwed. While tightening the nut 48, the upper rigid plate 6 and the lower rigid plate 1 press the coupling buffer material 21 to contract it, tighten it to a predetermined torque value, and fix it to the nut 48.
[0052]
(3) An anchor bar 49 for fixing the footing 51 and the ready-made pile 42 is integrally formed at the upper end of each fixing bar 44, 44 (FIGS. 3 and 4). Usually, the fixing reinforcing bars 44 and the anchor bars 49 are formed from an integral steel material.
[0053]
A leveled concrete layer 59 is formed on the gravel layer 58 before and after the fixing work of the anchor bars 49. The lower end portion of the protective cylinder 12 is leveled and embedded in the concrete layer 59, and the leveled concrete layer 59 reaches the side surface of the ready-made pile 42. In general, since the leveled concrete layer 59 is thin and the concrete is silently placed, there is no risk that the concrete will enter the upper side of the protective cylinder 12, and further, since the rubber ring 46 is in elastic contact, the concrete is not in the protective cylinder 12. Can be reliably prevented from entering above.
[0054]
(4) On the leveled concrete layer 59, reinforcing bars 50, 50 for footing of the upper structure are arranged on the outer peripheral side of the upper rigid plate 6 and the protective cylinder 12, and if necessary, anchor reinforcing bars 49, 49 and In addition, a formwork for footing is constructed (not shown), and concrete is placed in the formwork.
[0055]
(5) After the concrete is solidified, the foundation pile 43 and the footing 51 including the ready-made pile 42 embedded in the pile hole 24 are combined.
[0056]
[4] Explanation of stress transmission
[0057]
(1) When a long-term load is applied (normal time when only a vertical load is applied)
[0058]
The load of the superstructure is received by the footing 51, transmitted to the ready-made pile 42 through the entire pile head joint 22, and is borne by the foundation pile 43.
[0059]
On the other hand, since the nut 48 is tightened with a predetermined torque value, a repulsive force is generated in the first cushioning material 15 according to the magnitude of the torque value, and a part of the load is borne. The tightening of the first buffer material is adjusted within the elastic deformation of the first buffer material 15 (FIGS. 6A and 6B).
[0060]
(2) When a horizontal load is applied (short term such as an earthquake)
[0061]
When a horizontal force (horizontal load) is applied to the pile head due to an earthquake or the like, a bending moment is generated in the pile head of the ready-made pile 42, and the upper rigid plate 6 and the lower rigid plate 1 act so as to be displaced. Specifically, a change occurs such that one side of the upper rigid plate 6 is raised and the other side is lowered. This change is first absorbed by deformation (elastic stress) of the first cushioning material 15 and the second cushioning material 19 (see FIG. 6 (c)) When a larger bending moment is generated, in addition to the stress absorption by the first and second buffer members 15 and 19, the bending moment is absorbed by the deformation due to the extension of the rigidly-bonded fixing bar 44 and the like. It has a structure. Also in this case, the first and second buffer materials 15 and 19 are maintained so as to follow the deformation within the elastic deformation.
[0062]
Further, when the pile head of the ready-made pile 42 moves, a portion where the distance between the outer surface of the ready-made pile 42 and the inner surface of the protection cylinder 12 is shortened is absorbed by the rubber ring 46, and the ready-made pile 42 The protective cylinder 12 is not damaged.
[0063]
Further, the through holes 9 and 4 of the upper and lower rigid plates 6 and 1 are formed sufficiently large in diameter with respect to the shaft diameter of the fixing reinforcing bar 44, and the fixing reinforcing bar 44 is changed to this diameter in accordance with the displacement of the pile head of the ready-made pile 42. It is moved within the range of the gap to reduce damage and deformation.
[0064]
[5] Other embodiments
[0065]
(1) In the said Example, although the lower rigid board 1, the coupling | bonding shock absorbing material 21, and the upper rigid board 6 were mounted in order on the pile head of the ready-made pile 42, the pile head joint tool 22 was formed, 22, and through the through holes 4, 9, and 18 of the pile head joint tool 22 through the fixing rebar 44 fixed to the upper end plate 38, the pile head joint tool 22 is attached to the upper end plate 38 of the ready-made pile 42. It can also be placed.
[0066]
(2) Moreover, in the said Example, after fixing the fixing reinforcement 44 to the screw hole 40 of the upper end plate 38 of the ready-made pile 42, the pile head joint tool (upper and lower rigid board 6, 1, buffer material 15, 19) 22 is attached. However, after the pile head joint device 22 is first placed on the upper end plate 38 of the ready-made pile 42, the through holes 9, 18, 4 of the pile head joint device 22 are passed through, and the lower end portion of the anchoring reinforcing bar 44 is attached. It can also be screwed into the screw hole 40.
[0067]
(3) In the above-described embodiment, the fixing reinforcing bar 44 and the anchor reinforcing bar 49 are formed from an integral steel material. However, the fixing reinforcing bar 44 and the anchor reinforcing bar 49 manufactured separately are integrally joined by welding or the like. You can also In this case, it is desirable to perform welding at the factory instead of on-site welding because of reliability related to bonding strength.
[0068]
(4) Further, when the fixing reinforcing bar 44 and the anchor reinforcing bar 49 are separately formed as in the above (3), instead of fixing the anchor reinforcing bar 49 to the fixing reinforcing bar 44 or fixing to the fixing reinforcing bar 44, Further, the anchor bars 49 can be fixed to the upper rigid plate 6 (not shown). Even when the fixing reinforcing bar 44 and the anchor bar 49 are integrally formed, another anchor bar 49 can be fixed to the upper rigid plate 6 (not shown).
[0069]
(5) In the above embodiment, the fixing reinforcing bar 44 is screwed to the upper end plate 38 of the ready-made pile 42 and fixed to the ready-made pile 42, but is welded to the upper end plate 38 or screwed to the upper end plate 38. Further, it can be further welded and fixed.
[0070]
(6) In the above embodiment, the lower end portion of the protective cylinder 12 is embedded in the leveled concrete layer 59, so that it is possible to reliably prevent the concrete from entering the protective cylinder 12, but it is preferable to directly footing. It can also be embedded in 51 (not shown).
[0071]
(7) The pile head joint tool 22 is attached to the foundation pile 43 after the construction of the foundation pile 43 is completed, but when the foundation pile 43 is configured using the ready-made pile 42, The ready-made pile 42 can also be embedded in the pile hole 24 (not shown) with the pile head joint tool 22 attached to the upper end plate.
[0072]
【The invention's effect】
(1) In this invention, the lower part of the fixing steel material is fixed and fixed to the foundation pile, the intermediate part is fixed to the pressed pile head joint tool within the range of maintaining the elasticity of the cushioning material, and the upper end part in the upper structure. Since it is fixed, the normal vertical load of the superstructure is transmitted to the foundation pile via the fixing steel material and the cushioning material of the pile head joint tool. At this time, the amount of the vertical load to be borne by the buffer material is determined according to the pressing force of the buffer material, and the amount of the vertical load to be borne by the fixing steel material can be reduced.
[0073]
Therefore, the high bearing capacity pile can increase the bearing capacity to be borne by one foundation pile, but with this, the vertical load to be borne by one is set large, However, it is possible to select a material having a higher proof stress as the corresponding fixing steel material, or to reduce the number of fixing steel materials.
[0074]
(2) Therefore, when the superstructure and the foundation pile are connected, the rigid connection has been used regularly. However, in the combined structure of the upper structure and the foundation pile of the present invention, the fixed steel material to be rigidly connected to the foundation pile is difficult to make full use of. Combined with cushioning material, the load of bending moment is distributed to reduce the burden of anchoring steel material. Therefore, even for foundation piles with high bearing capacity, they have a high yield strength that is balanced against both vertical and horizontal loads. Structure can be provided easily.
[0075]
In addition, when the rigid coupling part and the cushioning material are fixed by tightening with bolts and nuts, compared to various types of seismic isolation structures that support all loads with conventionally proposed special laminated rubber and dampers, The seismic isolation structure can be easily realized, and the cushioning material can be controlled and used within its elastic range, so that it is possible to prevent deterioration of the cushioning material during normal long-term load.
Therefore, the selection range of the buffer material to be used can be widened.
[0076]
(3) In addition, when a screw part is formed in the fixing steel material and the nut is screwed together, and the nut is placed on the top surface of the pile head joint tool and fastened, the tightening torque value of the nut should be managed. It is possible to manage the pressure applied to the buffer material when a horizontal load such as an earthquake is applied, and the bending moment that the fixing steel material should bear. Therefore, there is an effect that the desired pressure of the buffer material and the compressive stress of the fixing steel material can be easily set.
[0077]
Since the torque value is managed, the correlation between the torque value and the pressure applied to the buffer material can be easily analyzed. If a torque wrench or the like is used, the desired torque value can be easily managed on site.
[0078]
Moreover, the joining work of ready-made pile and pile head joint tool becomes easy.
[0079]
Further, if a threaded portion is also formed on the lower end side of the fixing steel material, when a ready-made pile is used, the fixing steel material can be fixed and fixed easily using the screw holes formed in the upper end plate.
[0080]
(4) In addition, when a pile head joint is constructed using a protective cylinder with a diameter larger than that of the pile head of the foundation pile, ensure a space for moving the pile head and cushioning material when a horizontal load is applied. Thus, the range in which damage to the pile head and the upper structure can be prevented can be expanded.
[0081]
Further, in this case, if an elastic material is inserted between the pile head and the protective cylinder, damage can be prevented further and the pile head can be urged to return to its current state after moving by elastic force. Furthermore, it is possible to prevent the concrete from entering the inside of the protective cylinder when placing the superstructure concrete.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a front view showing a structure of a member according to an embodiment of the present invention, with a left side broken.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a front view in which the left side of the constructed state is cut off.
FIG. 4 is a front view in which the left side of the constructed state is cut off.
FIGS. 5A to 5D are longitudinal sectional views for explaining a process of constructing a foundation pile used for carrying out the present invention.
FIGS. 6A and 6B are conceptual diagrams showing deformation of the cushioning material according to the present invention, wherein FIG. 6A shows a state before tightening, FIG. 6B shows a state in which a bending moment is applied, and FIG.
[Explanation of symbols]
1 Lower rigid plate
2 Outer circumference of lower rigid plate
4 Lower rigid plate through hole
6 Upper rigid board
7 outer circumference of upper rigid plate
9 Through hole in upper rigid plate
10 Notch in upper rigid plate
12 protection cylinder
13 Inner surface of protective cylinder
13a Outer surface of protective cylinder
15 First cushioning material
16 Outer circumference of first cushioning material
18 Through-hole of first buffer material
19 Second cushioning material
20 Upper surface of the second cushioning material
20a The bottom surface of the second cushioning material
21 Bonded cushioning material
22 Pile head joint tool
24 Pile hole
24a Pile hole shaft
25 Expanded bottom hardened part of pile hole
28 ground
30 Lower pile (off-the-shelf pile)
36 Upper pile (off-the-shelf pile)
38 Top plate
39 Hollow part of upper end plate
40 Screw hole on top plate
42 Ready-made piles
43 Foundation pile
44 Anchor reinforcement
46 Rubber Ring
47 Spacer
48 nuts
49 Anchor muscle
50 Reinforcing bars for footing
51 Footing
53 Foundation pile structure
55, 56 soil cement layer
59 Leveled concrete layer

Claims

While mounting a pile head joint tool with a cushioning material between the upper and lower rigid plates on the upper end plate of the foundation pile built in the ground by burying the ready-made pile in the pile hole The fixing steel material has a lower end fixed to a screw hole of the upper end plate of the ready-made pile, and the upper portion of the fixing steel material protrudes upward from a through hole formed in the pile head joint device, and the cushioning material is pressed. The intermediate pile of the fixing steel material is fixed to the pile head joint device, and the fixing steel material is fixed in the upper structure.

A state in which a threaded portion is formed in the fixing steel material and a nut is screwed, the nut is arranged and fastened on the upper surface of the pile head joint device, and the cushioning material of the pile head joint device is maintained at a predetermined pressure The connection structure between the foundation pile and the upper structure according to claim 1, wherein the fixing steel material is fixed to an upper rigid plate of the pile head joint tool.

The pressing of the buffer material is a first component force transmitted from the fixed steel material directly to the foundation pile among the vertical loads transmitted from the superstructure to the fixed steel material, and the buffer material from the fixed steel material via the buffer material. The connection structure of the foundation pile and upper structure of Claim 1 or 2 which adjusted and pressed the 2nd component force transmitted to a foundation pile so that said 2nd component force might become a desired value.

A lower rigid plate for placing the pile head joint tool on the foundation pile and an upper rigid plate having a protective cylinder covering the pile head of the foundation pile are arranged in parallel vertically between the upper rigid plate and the lower rigid plate. In addition, a cushioning material is interposed between the lower rigid plate and the protective cylinder, and the space between the lower end inner surface of the protective cylinder and the pile head outer surface of the foundation pile is closed with an elastic material. The connecting structure of a foundation pile and an upper structure according to claim 1.

A lower base plate that can be installed on the upper surface of the upper end plate having a hollow portion of a ready-made pile, and an upper base plate are stacked vertically with a cushioning material interposed therebetween to form a joint base material. A through hole through which the fixing steel material fixed to the screw hole of the upper end plate of the pile can be passed, and the upper end portion of the protective cylinder capable of covering the outside of the joint base material is fixed to the upper rigid plate. A pile head joint device, wherein a cushioning material is inserted between the inner surface of the protective cylinder and the outer periphery of the lower rigid plate.

The outer diameter of the upper rigid plate is larger than the outer diameter of the lower rigid plate, the upper end of the protective cylinder is attached along the outer periphery of the upper rigid board, and the protective cylinder is formed to be larger than the pile head of the foundation pile The pile head joint tool according to claim 5, wherein the pile head joint tool is provided.

A method of connecting a foundation pile and a superstructure characterized by taking the following steps.
(1) Expose the pile head and build the foundation pile.
(2) From the upper end of the foundation pile, the fixed steel material with the lower end fixed and fixed to the foundation pile is protruded upward.
(3) pile head joint member is on the outer peripheral side of the vertical direction of the buffer material provided with a vertically through-hole, is provided with a horizontal cushioning material, in the vertical direction of the through hole of the pile head joint member, while passing the fixing steel, the upper end of the foundation pile, mounting the pile head joint member.
(4) The intermediate portion of the fixing steel material is fixed to the pile head joint device while maintaining the state where the vertical cushioning material is pressed at a predetermined pressure.
(5) In the vertical load from the upper structure transmitted to the fixing steel material, the vertical buffer material is pressed by a first component force transmitted directly from the fixing steel material to the foundation pile, and the fixing steel material. The second component force transmitted to the foundation pile via the cushioning material in the vertical direction is adjusted and pressed so that the second component force becomes a desired value.
(6) Placing concrete for superstructure to fix the fixing steel and pile head joints in the superstructure.