JP2004124452A

JP2004124452A - Foundation pile structure in bearing ground and working method of foundation pile

Info

Publication number: JP2004124452A
Application number: JP2002288418A
Authority: JP
Inventors: Sadao Yabuuchi; 藪内　貞男
Original assignee: Geotop Corp
Current assignee: Geotop Corp
Priority date: 2002-10-01
Filing date: 2002-10-01
Publication date: 2004-04-22
Anticipated expiration: 2022-10-01
Also published as: JP4057873B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foundation pile structure in a bearing ground capable of obtaining the bearing capacity of a pile at a widened bottom, and at the same time, a bearing lateral load and displacement in an upper stratum and carrying out work at a low cost even in the ground having the bearing capacity of a lower layer with a soft upper layer. <P>SOLUTION: In the foundation pile structure in the bearing ground embedding a prefabricated pile 2 in a pile hole 1 having the widened bottom 11, a knotted prefabricated concrete pile is placed as a lower pile 21 embedded in the widened bottom 11, and at the same time, a prefabricated cylinder concrete pile is placed as an intermediate pile 22 connected to the upper part of the lower pile 21, and a prefabricated cylinder pile having the approximately same diameter as that of the cylinder concrete pile as an upper pile 23 connected to the upper part of the intermediate pile 22 and having flexural rigidity higher than that of the cylinder concrete pile is placed. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、支持力を得る支持層に拡底部を有する杭孔を掘削し、該杭孔に既製杭を埋設する支持地盤における基礎杭構造及び基礎杭の施工法に関するものである。
【０００２】
【従来の技術】
従来より、杭の支持力及び引き抜き抵抗を増加させるための手段として、杭の下端に拡底部を設ける拡底杭が広く知られている。
この場合、拡底杭としては、現場打ち杭の下端に拡底部を設けるものと、既製杭の下端に拡底部を設けるものとがあり、いずれも予め杭孔の底部に杭径よりも大径な拡底部を掘削しておき、この拡底部内にコンクリートを打設して拡底杭とする。
既製杭による拡底杭としては、既製杭の埋設前又は埋設後に、杭孔内にセメントミルクを注入し固化させる方法が一般によく知られており、また、杭の外周に節を設けた節杭も使用されている。
【０００３】
【発明が解決しようとする課題】
しかしながら、上記従来の支持地盤における基礎杭の施工法は、杭孔の全長に亘ってコンクリート杭を埋設することから、上層が軟弱で下層が支持力を有する地盤に既製杭を埋設する場合は、拡底部での杭の支持力は得られたとしても、上層の地盤での横方向の荷重と変位にコンクリート杭の上部が耐えられないという問題が発生する。
【０００４】
本発明は、上記従来の支持地盤における基礎杭の施工法が有する問題点に鑑み、拡底部で杭の支持力を得るとともに、上層が軟弱で下層が支持力を有する地盤でも、上層の地盤での横方向の荷重と変位に耐え、しかも低コストで施工することができる支持地盤における基礎杭構造及び基礎杭の施工法を提供することを目的とする。
【０００５】
【課題を解決するための手段】
上記目的を達成するため、本発明の支持地盤における基礎杭構造は、拡底部を有する杭孔に既製杭を埋設する支持地盤における基礎杭構造において、拡底部に埋設される下部杭として既製の節付きコンクリート杭を配設するとともに、下部杭の上部に連結される中間杭として既製の円筒コンクリート杭を配設し、中間杭の上部に連結される上部杭として前記円筒コンクリート杭と略同径で、該円筒コンクリート杭より曲げ剛性の大きな既製円筒杭を配設したことを特徴とする。
【０００６】
また、同じ目的を達成するため、本発明の支持地盤における基礎杭の施工法は、拡底部を有する杭孔に既製杭を埋設する支持地盤における基礎杭の施工法において、拡底部に埋設される下部杭として既製の節付きコンクリート杭を配設するとともに、下部杭の上部に連結される中間杭として既製の円筒コンクリート杭を配設し、中間杭の上部に連結される上部杭として前記円筒コンクリート杭と略同径で、該円筒コンクリート杭より曲げ剛性の大きな既製円筒杭を配設することを特徴とする。
【０００７】
この支持地盤における基礎杭構造及び基礎杭の施工法は、拡底部に埋設される下部杭として既製の節付きコンクリート杭を配設することから、拡底部で杭の支持力を得るとともに、中間杭を介して連結される上部杭として、中間杭として配設する既製の円筒コンクリート杭と略同径で、該円筒コンクリート杭より曲げ剛性の大きな既製円筒杭を配設することから、上層が軟弱で下層が支持力を有する地盤でも、上層の地盤での横方向の荷重と変位に耐えることができ、さらに、下部杭の上部に連結される中間杭として既製の円筒コンクリート杭を配設することから、上層が軟弱で下層が支持力を有する地盤でも低コストで施工することができる。
【０００８】
この場合において、中間杭として下部の節付きコンクリート杭の軸部と略同径の既製の円筒コンクリート杭を配設するようにしたり、下部の節付きコンクリート杭の節部と略同径の既製の円筒コンクリート杭を配設するようにすることができる。
【０００９】
これにより、中間杭と下部の節付きコンクリート杭との接続を簡易に、かつ強固に行うことができる。
【００１０】
また、杭孔と杭の隙間に膨張・固化性を有するスラグを充填し、該スラグを膨張させながら固化させることができる。
【００１１】
これにより、スラグが膨張、固化することにより、スラグが既製杭を拘束することに加えて、杭孔周囲の地盤を締め固め、相対密度が増大し、これにより、孔壁からの側圧が増して既製杭がさらに拘束され、既製杭と杭孔が一体となって、その鉛直支持力と水平耐力を増強することができる。
【００１２】
また、拡底部の下部に根固め用スラグを投入し、該根固め用スラグの上に前記節付きコンクリート杭を建てることができる。
【００１３】
これにより、既製杭の下部の地盤を固め、基礎杭の鉛直支持力を一層高めることができる。
【００１４】
また、根固め用スラグとして、固化剤を添加した膨張・固化性を有するスラグを用いることができる。
【００１５】
これにより、既製杭の下部の地盤を固め、基礎杭の鉛直支持力をさらに高めることができる。
【００１６】
また、膨張・固化性を有するスラグとして、製鋼スラグ（転炉スラグ及び／又は電気炉スラグ（酸化スラグ及び／又は還元スラグ）をいい、ここでは、特に、エージング処理を行っていない製鋼スラグのほか、エージング処理を部分的に行うことにより膨張性を調整した製鋼スラグ等の膨張性を消失させていない製鋼スラグをいう。）、ゴミ焼却スラグ、汚泥スラグの１種若しくは２種以上の混合物を用いることができる。
さらに、膨張・固化性を有するスラグは、単独で用いるほか、これに、膨張性を消失した製鋼スラグ、高炉スラグ、フェロアロイスラグ、水砕スラグ、銅製錬スラグ、赤泥、フライアッシュ、ゴミ焼却灰、ガラス破砕物、廃石膏、コンクリート廃材等の産業廃棄物、石膏、生石灰、セメント、砕石、土砂、粘土等の建築用材料、人工材料、鉱物の１種若しくは２種以上を混合した、膨張性及び固化性を有するスラグの膨張性及び固化性を利用できるものを用いることができる。
【００１７】
これにより、膨張・固化性を有するスラグが吸水し、膨張、固化することによって、杭孔と杭の隙間が狭い場合等でも、杭孔と杭の隙間を、均一に空洞を形成することなく充填することができるとともに、深層部にも圧縮力を伝達することができ、杭の周囲の地盤を容易に、静的に、かつ確実に締め固めることができ、地盤の支持力を高め、これによって、杭の支持力を高めることができる。
また、産業廃棄物である製鋼スラグ等の有効利用を図ることができる。
【００１８】
また、杭孔の拡底部を、前記節付きコンクリート杭の略全長に亘る深さに掘削することができる。
【００１９】
これにより、杭の拘束力を増大し、既製杭の鉛直支持力と水平耐力を増強することができる。
【００２０】
また、中間杭が上載荷重を支持する必要耐力を有し、かつ上部杭よりも曲げ剛性が小さくなるようにすることができる。
【００２１】
これにより、上層の地盤で上部杭が受けた横方向の荷重を、この中間杭が撓むことによって吸収することができる。
【００２２】
【発明の実施の形態】
以下、本発明の支持地盤における基礎杭構造及び基礎杭の施工法の実施の形態を図面に基づいて説明する。
【００２３】
図１に、本発明の支持地盤における基礎杭構造及び基礎杭の施工法の一実施例を示す。
この基礎杭構造は、拡底部１１を有する杭孔１に既製杭２を埋設するもので、拡底部１１に埋設される下部杭２１として既製の節付きコンクリート杭を配設するとともに、下部杭２１の上部に連結される中間杭２２として前記節付きコンクリート杭の軸径と略同径の既製の円筒コンクリート杭を配設し、中間杭２２の上部に連結される上部杭２３として、中間杭２２として用いる円筒コンクリート杭と略同径で、この円筒コンクリート杭より曲げ剛性の大きな、鋼管杭、ＳＣ杭、ＰＲＣ杭等の複合杭等の既製円筒杭を配設している。
【００２４】
この場合、図１及び図２（ａ）に示すように、中間杭２２としては、下部の節付きコンクリート杭２１の軸部と略同径の既製の円筒コンクリート杭を用いるほか、図２（ｂ）及び（ｃ）に示すように、下部の節付きコンクリート杭２１の節部と略同径の既製の円筒コンクリート杭（ここで、下部杭２１と中間杭２２との接続は、図２（ｂ）に示すように、下部杭２１に、その上端部を節部と略同径の大径に形成した節付きコンクリート杭を用いたり、図２（ｃ）に示すように、テーパ形状の継手２４を用いるようにすることができる。）を配設するようにすることができる。また、図示しないが、中間杭２２と上部杭２３の接続は、図２（ｃ）と同様にして、上部杭２３の径を大径にすることができる。
これにより、中間杭２２と上部杭２３の軸径を大きくすることができ、水平耐力を増強することができる。
【００２５】
基礎杭の施工手順としては、まず、図１（ａ）に示すように、オーガーヘッド（図示省略）等により、上部構造物を支持できる地盤まで地盤を掘削し、図１（ｂ）に示すように、掘削した杭孔１の底部を拡径して拡底部１１を形成する。
次に、図１（ｃ）、（ｄ）に示すように、杭孔１の底部に既製杭２を建て、杭孔１と既製杭２の隙間に膨張・固化性を有するスラグ３を充填し、該スラグ３を膨張させながら固化させる。
これにより、スラグ３が膨張、固化することにより、杭孔１周囲の地盤を締め固め、相対密度が増大し、これにより、孔壁からの側圧が増して既製杭２が拘束され、既製杭２と杭孔１が一体となって、その鉛直支持力と水平耐力を増強することができる。
この場合、スラグ３は拡底部１１付近に充填し、後の杭孔１には、セメントミルク、ソイルセメント５等を充填するようにしたり、拡底部１１から杭孔の上部まですべてに充填することができる。
【００２６】
また、図３（ａ）に示すように、拡底部１１の下部に根固め用スラグ４を、杭径Ｄの１Ｄ〜３Ｄの層厚となるように投入し、該根固め用スラグ４の上に前記節付きコンクリート杭を建てることも可能であり、これにより、既製杭の下部の地盤を固め、基礎杭の鉛直支持力を一層高めることができるようにしたものである。
この場合、根固め用スラグ４として、セメント、石膏、水砕スラグ、還元スラグ等の固化剤を添加した膨張・固化性を有するスラグ（後述）を用いることができ、これにより、既製杭２の下部の地盤を固め、基礎杭の鉛直支持力をさらに高めることができる。
【００２７】
一方、スラグ３としては、膨張・固化性を有するスラグ、具体的には、製鋼スラグ（転炉スラグ及び／又は電気炉スラグ（酸化スラグ及び／又は還元スラグ）をいい、ここでは、特に、エージング処理を行っていない製鋼スラグのほか、エージング処理を部分的に行うことにより膨張性を調整した製鋼スラグ等の膨張性を消失させていない製鋼スラグをいう。）、ゴミ焼却スラグ、汚泥スラグの１種若しくは２種以上の混合物を用いることができる。
さらに、膨張・固化性を有するスラグは、単独で用いるほか、これに、膨張性を消失した製鋼スラグ、高炉スラグ、フェロアロイスラグ、水砕スラグ、銅製錬スラグ、赤泥、フライアッシュ、ゴミ焼却灰、ガラス破砕物、廃石膏、コンクリート廃材等の産業廃棄物、石膏、生石灰、セメント、砕石、土砂、粘土等の建築用材料、人工材料、鉱物の１種若しくは２種以上を混合した、膨張性及び固化性を有するスラグの膨張性及び固化性を利用できるものを用いることができる。
これにより、膨張・固化性を有するスラグが吸水し、膨張、固化することによって、杭孔と杭の隙間が狭い場合等でも、杭孔と杭の隙間を、均一に空洞を形成することなく充填することができるとともに、深層部にも圧縮力を伝達することができ、杭の周囲の地盤を容易に、静的に、かつ確実に締め固めることができ、地盤の支持力を高め、これによって、杭の支持力を高めることができる。
また、産業廃棄物である製鋼スラグ等の有効利用を図ることができる。
【００２８】
また、図３（ｂ）に示すように、杭孔１の拡底部１１を、下部杭２１である節付きコンクリート杭の略全長に亘る深さに掘削することができる。
これにより、既製杭２の拘束力を増大し、基礎杭の鉛直支持力と水平耐力を増強することができる。
【００２９】
また、図３（ｂ）に示すように、杭孔１の直径Ｄ_Ｈを、上部杭２３の直径Ｄの２倍以上、より具体的には、２〜４倍（図３（ｂ）に示す実施例では、約３倍）とすることができる。
これにより、杭孔１と杭２の隙間に膨張・固化性を有するスラグを充填することによって、杭の周囲の地盤を容易に、静的に、かつ一層確実に締め固めることができ、地盤の支持力を高め、これによって、杭の支持力を高めることができる。
また、杭孔１の掘削長により、中間杭を必要本数継ぎ足すことができる。
【００３０】
また、中間杭２２は、上載荷重を支持する必要耐力を有し、かつ上部杭２３よりも曲げ剛性が小さくなるようにすることができる。
これにより、上層の地盤で上部杭２３が受けた横方向の荷重と変位を、この中間杭２２が撓むことによって吸収することができる。
【００３１】
かくして、この実施例の支持地盤における基礎杭構造及び基礎杭の施工法は、拡底部１１に埋設される下部杭２１として既製の節付きコンクリート杭を配設することから、拡底部１１で杭の支持力を得るとともに、中間杭２２を介して連結される上部杭２３として既製の円筒鋼管杭を配設することから、上層が軟弱で下層が支持力を有する地盤でも、上層の地盤での横方向の荷重と変位に耐えることができ、さらに、下部杭２１の上部に連結される中間杭２２として既製の円筒コンクリート杭を配設することから、上層が軟弱で下層が支持力を有する地盤でも低コストで施工することができる。
【００３２】
【実施例】
杭孔１と既製杭２の隙間に膨張・固化性を有するスラグ３を充填し、該スラグ３を膨張させながら固化させることによる杭の支持力（第２限界荷重：杭先端直径の１０％相当の杭先端沈下量が生じたときの荷重）の経時的な変化を、充填材として一般的に用いられるセメントミルクと比較するために行った現場規模実験の結果を、表１に示す。
なお、行った現場規模実験は、以下のとおりである。
【００３３】
［現場規模実験］
地盤：Ｎ値２〜１２、平均Ｎ値６の軟弱地盤
杭種：コンクリート節杭　φ４４０−３００　Ａ種　１１ｍ
杭Ｎｏ．▲１▼は、原地盤を掘削して杭を建て込み、杭孔と既製杭の隙間に膨張・固化性を有する製鋼スラグを充填した。
杭Ｎｏ．▲２▼は、原地盤を掘削して杭を建て込み、杭孔と既製杭の隙間にセメントミルクを注入して、ソイルセメント層を形成した。
【００３４】
【表１】

【００３５】
表１に示すように、製鋼スラグを充填した杭Ｎｏ．▲１▼は、３ヶ月養生支持力／１ヶ月養生支持力（＝１．２７）及び第２限界荷重の値が共にソイルセメント層を形成した杭Ｎｏ．▲２▼のそれより大きな値を示しており、これにより、製鋼スラグが膨張、固化することによって、杭の支持力を高めることができることを確認した。
【００３６】
以上、本発明の支持地盤における基礎杭構造及び基礎杭の施工法を実施例に基づいて説明したが、本発明は、この実施例の記載に限定されるものではなく、その要旨を逸脱しない範囲において適宜に変更することが可能である。
【００３７】
【発明の効果】
本発明の支持地盤における基礎杭構造及び基礎杭の施工法によれば、拡底部に埋設される下部杭として既製の節付きコンクリート杭を配設することから、拡底部で杭の支持力を得るとともに、中間杭を介して連結される上部杭として、中間杭として配設する既製の円筒コンクリート杭と略同径で、該円筒コンクリート杭より曲げ剛性の大きな既製円筒杭を配設することから、上層が軟弱で下層が支持力を有する地盤でも、上層の地盤での横方向の荷重と変位に耐えることができ、さらに、下部杭の上部に連結される中間杭として既製の円筒コンクリート杭を配設することから、上層が軟弱で下層が支持力を有する地盤でも低コストで施工することができる。
【００３８】
また、中間杭として下部の節付きコンクリート杭の軸部と略同径の既製の円筒コンクリート杭を配設するようにしたり、下部の節付きコンクリート杭の節部と略同径の既製の円筒コンクリート杭を配設するようにすることにより、中間杭と下部の節付きコンクリート杭との接続を簡易に、かつ強固に行うことができる。
【００３９】
また、杭孔と杭の隙間に膨張・固化性を有するスラグを充填し、該スラグを膨張させながら固化させることにより、スラグが膨張、固化することにより、スラグが既製杭を拘束することに加えて、杭孔周囲の地盤を締め固め、相対密度が増大し、これにより、孔壁からの側圧が増して既製杭がさらに拘束され、既製杭と杭孔が一体となって、その鉛直支持力と水平耐力を増強することができる。
【００４０】
また、拡底部の下部に根固め用スラグを投入し、該根固め用スラグの上に前記節付きコンクリート杭を建てることにより、既製杭の下部の地盤を固め、基礎杭の鉛直支持力を一層高めることができる。
【００４１】
また、根固め用スラグとして、固化剤を添加した膨張・固化性を有するスラグを用いることにより、既製杭の下部の地盤を固め、基礎杭の鉛直支持力をさらに高めることができる。
【００４２】
また、膨張・固化性を有するスラグとして、製鋼スラグ（転炉スラグ及び／又は電気炉スラグ（酸化スラグ及び／又は還元スラグ）をいい、ここでは、特に、エージング処理を行っていない製鋼スラグのほか、エージング処理を部分的に行うことにより膨張性を調整した製鋼スラグ等の膨張性を消失させていない製鋼スラグをいう。）、ゴミ焼却スラグ、汚泥スラグの１種若しくは２種以上の混合物を用いるようにし、さらに、膨張・固化性を有するスラグは、単独で用いるほか、これに、膨張性を消失した製鋼スラグ、高炉スラグ、フェロアロイスラグ、水砕スラグ、銅製錬スラグ、赤泥、フライアッシュ、ゴミ焼却灰、ガラス破砕物、廃石膏、コンクリート廃材等の産業廃棄物、石膏、生石灰、セメント、砕石、土砂、粘土等の建築用材料、人工材料、鉱物の１種若しくは２種以上を混合した、膨張性及び固化性を有するスラグの膨張性及び固化性を利用できるものを用いることにより、膨張・固化性を有するスラグが吸水し、膨張、固化することによって、杭孔と杭の隙間が狭い場合等でも、杭孔と杭の隙間を、均一に空洞を形成することなく充填することができるとともに、深層部にも圧縮力を伝達することができ、杭の周囲の地盤を容易に、静的に、かつ確実に締め固めることができ、地盤の支持力を高め、これによって、杭の支持力を高めることができる。
また、産業廃棄物である製鋼スラグ等の有効利用を図ることができる。
【００４３】
また、杭孔の拡底部を、前記節付きコンクリート杭の略全長に亘る深さに掘削することにより、杭の拘束力を増大し、既製杭の鉛直支持力と水平耐力を増強することができる。
【００４４】
また、中間杭が上載荷重を支持する必要耐力を有し、かつ上部杭よりも曲げ剛性が小さくなるようにすることにより、上層の地盤で上部杭が受けた横方向の荷重を、この中間杭が撓むことによって吸収することができる。
【図面の簡単な説明】
【図１】本発明の支持地盤における基礎杭構造及び基礎杭の施工法の一実施例を示し、（ａ）は杭孔を示す断面図、（ｂ）は拡底部を掘削した杭孔を示す断面図、（ｃ）は杭孔に既製杭を建て、スラグを充填した状態を示す断面図、（ｄ）は杭孔にスラグを充填した状態のスラグの膨張特性を示す説明図である。
【図２】本発明の基礎杭構造を示し、（ａ）は中間杭の杭径を下部杭の軸径とほぼ等しくした実施例を示す断面図、（ｂ）、（ｃ）は中間杭の杭径を下部杭の節径とほぼ等しくした実施例を示す断面図である。
【図３】本発明の基礎杭構造を示し、（ａ）は拡底部の下部に根固め用スラグを投入するようにした実施例を示す断面図、（ｂ）は杭孔の拡底部を節付きコンクリート杭の略全長に亘る深さに掘削するようにした実施例を示す断面図である。
【符号の説明】
１　　杭孔
１１　拡底部
２　　既製杭
２１　下部杭
２２　中間杭
２３　上部杭
３　　スラグ
４　　根固め用スラグ
５　　セメントミルク[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a foundation pile structure and a method for constructing a foundation pile in a supporting ground in which a pile hole having an expanded bottom portion is excavated in a support layer having a supporting force, and a ready-made pile is buried in the pile hole.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a means for increasing a supporting force and a pull-out resistance of a pile, an expanded pile having an expanded bottom at a lower end of the pile has been widely known.
In this case, there are two types of expanded piles, one with an expanded bottom at the lower end of the cast-in-place pile, and another with an expanded bottom at the lower end of the ready-made pile, both of which have a diameter larger than the pile diameter at the bottom of the pile hole in advance. The expanded bottom is excavated, and concrete is poured into the expanded bottom to form an expanded pile.
As a method for expanding piles with prefabricated piles, it is generally well-known that cement milk is injected into the pile hole and solidified before or after burying of prefabricated piles. It is used.
[0003]
[Problems to be solved by the invention]
However, the method of constructing a foundation pile in the conventional support ground described above involves burying a concrete pile over the entire length of the pile hole, so when burying a ready-made pile in the ground where the upper layer is soft and the lower layer has a supporting force, Even if the support capacity of the pile at the bottom is obtained, there is a problem that the upper part of the concrete pile cannot withstand the lateral load and displacement on the upper layer ground.
[0004]
The present invention, in view of the problems of the conventional method of constructing a foundation pile in the supporting ground, obtains the supporting force of the pile at the expanded bottom portion, and also in the ground where the upper layer is soft and the lower layer has the supporting force, even in the upper ground. It is an object of the present invention to provide a foundation pile structure and a method of constructing a foundation pile on a supporting ground, which can withstand the lateral load and displacement of the support pile and can be constructed at low cost.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a foundation pile structure in a support ground according to the present invention is a foundation pile structure in a support ground in which a ready-made pile is buried in a pile hole having a bottom expansion part. Along with the concrete pile, a ready-made cylindrical concrete pile is arranged as an intermediate pile connected to the upper part of the lower pile, and as an upper pile connected to the upper part of the intermediate pile, the same diameter as the cylindrical concrete pile is used. A prefabricated cylindrical pile having a greater bending rigidity than the cylindrical concrete pile is provided.
[0006]
In addition, in order to achieve the same object, the method of constructing a foundation pile in the support ground of the present invention is a method of constructing a foundation pile in a support ground in which a ready-made pile is buried in a pile hole having an enlarged bottom, and is buried in the expanded bottom. A ready-made knotted concrete pile is provided as a lower pile, a ready-made cylindrical concrete pile is provided as an intermediate pile connected to the upper part of the lower pile, and the cylindrical concrete pile is provided as an upper pile connected to the upper part of the middle pile. It is characterized in that a ready-made cylindrical pile having substantially the same diameter as the pile and having a higher bending rigidity than the cylindrical concrete pile is provided.
[0007]
The construction method of the foundation pile and the foundation pile on this supporting ground is to install a ready-made knotted concrete pile as the lower pile buried in the extension bottom, so that the support capacity of the pile is obtained at the extension and the intermediate pile As an upper pile connected via the same, a ready-made cylindrical pile having substantially the same diameter as a ready-made cylindrical concrete pile to be disposed as an intermediate pile and having a greater bending rigidity than the cylindrical concrete pile is disposed, so that the upper layer is soft. Even if the lower layer has a bearing capacity, it can withstand the lateral load and displacement on the upper layer, and furthermore, since the existing cylindrical concrete pile is installed as an intermediate pile connected to the upper part of the lower pile In addition, construction can be performed at low cost even on the ground where the upper layer is soft and the lower layer has a supporting force.
[0008]
In this case, a ready-made cylindrical concrete pile with the same diameter as the shaft of the lower knotted concrete pile may be installed as an intermediate pile, or a ready-made cylindrical concrete pile with the same diameter as the knot of the lower knotted concrete pile may be provided. A cylindrical concrete pile can be provided.
[0009]
This makes it possible to easily and firmly connect the intermediate pile and the lower concrete pile with joints.
[0010]
In addition, it is possible to fill the gap between the pile hole and the pile with slag having expandability and solidification properties, and to solidify the slag while expanding the slag.
[0011]
As a result, the slag expands and solidifies, and in addition to the slag constraining the ready-made pile, the ground around the pile hole is compacted and the relative density increases, thereby increasing the lateral pressure from the hole wall. The ready-made pile is further restrained, and the ready-made pile and the pile hole are integrated, so that the vertical bearing capacity and the horizontal strength can be enhanced.
[0012]
In addition, the slag for consolidation can be put into the lower part of the expanded bottom, and the concrete slag with nodes can be built on the slag for consolidation.
[0013]
Thereby, the ground below the ready-made pile can be solidified, and the vertical bearing capacity of the foundation pile can be further increased.
[0014]
In addition, as the slag for consolidation, a slag having a swelling / solidifying property to which a solidifying agent is added can be used.
[0015]
Thereby, the ground below the ready-made pile can be solidified, and the vertical bearing capacity of the foundation pile can be further increased.
[0016]
In addition, as slag having expandability and solidification properties, steelmaking slag (converter slag and / or electric furnace slag (oxidized slag and / or reduced slag) is referred to. In particular, here, steel slag not subjected to aging treatment is used. A steelmaking slag which does not lose its expansibility such as steelmaking slag whose expansibility has been adjusted by partially performing aging treatment), garbage incineration slag, and / or a mixture of two or more types of sludge slag. be able to.
In addition, slag having expandability and solidification properties is used alone, and in addition to steelmaking slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, garbage incineration Industrial expandable materials such as crushed glass, waste gypsum, concrete waste, gypsum, quicklime, cement, crushed stone, earth and sand, building materials, artificial materials, and one or more minerals. A slag having a solidifying property and capable of utilizing the expanding property and the solidifying property can be used.
[0017]
As a result, the slag having expandability and solidification absorbs water and expands and solidifies, so that even when the gap between the pile hole and the pile is narrow, the gap between the pile hole and the pile is filled without forming a uniform cavity. And compressive force can be transmitted to the deep part, the ground around the pile can be easily, statically and securely compacted, and the ground support capacity can be increased. , Can increase the supporting capacity of the pile.
In addition, it is possible to effectively use steelmaking slag, which is industrial waste.
[0018]
Further, the enlarged bottom portion of the pile hole can be excavated to a depth extending over substantially the entire length of the knotted concrete pile.
[0019]
Thereby, the restraining force of the pile can be increased, and the vertical supporting force and the horizontal strength of the ready-made pile can be enhanced.
[0020]
In addition, the intermediate pile has the necessary strength to support the overlying load, and the bending rigidity is smaller than that of the upper pile.
[0021]
Thereby, the lateral load received by the upper pile on the upper ground can be absorbed by the bending of the intermediate pile.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a foundation pile structure and a method of constructing a foundation pile on a supporting ground according to the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows an embodiment of a foundation pile structure and a method for constructing a foundation pile on a supporting ground according to the present invention.
In this foundation pile structure, a ready-made pile 2 is buried in a pile hole 1 having an enlarged bottom portion 11, and a ready-made knotted concrete pile is disposed as a lower pile 21 buried in the enlarged bottom portion 11, and a lower pile 21 is provided. A ready-made cylindrical concrete pile having substantially the same diameter as the shaft of the knotted concrete pile is disposed as an intermediate pile 22 connected to the upper part of the intermediate pile 22. A ready-made cylindrical pile, such as a composite pile such as a steel pipe pile, an SC pile, and a PRC pile, which has substantially the same diameter as the cylindrical concrete pile used as the above and has higher bending rigidity than the cylindrical concrete pile, is provided.
[0024]
In this case, as shown in FIG. 1 and FIG. 2A, as the intermediate pile 22, a ready-made cylindrical concrete pile having substantially the same diameter as the shaft of the lower noded concrete pile 21 is used. ) And (c), a ready-made cylindrical concrete pile having substantially the same diameter as the knot of the lower knotted concrete pile 21 (here, the connection between the lower pile 21 and the intermediate pile 22 is shown in FIG. 2), the lower pile 21 may be a knotted concrete pile whose upper end is formed to have a large diameter substantially the same as the knot portion, or a tapered joint 24 as shown in FIG. Can be used.). Although not shown, the connection between the intermediate pile 22 and the upper pile 23 can be made larger in the same manner as in FIG. 2C.
Thereby, the shaft diameter of the intermediate pile 22 and the upper pile 23 can be increased, and the horizontal strength can be enhanced.
[0025]
As a construction procedure of the foundation pile, first, as shown in FIG. 1 (a), the ground is excavated by an auger head (not shown) or the like to a ground capable of supporting the upper structure, and as shown in FIG. 1 (b). Then, the diameter of the bottom of the excavated pile hole 1 is expanded to form an expanded bottom 11.
Next, as shown in FIGS. 1 (c) and 1 (d), a ready-made stake 2 is erected at the bottom of the stake hole 1, and a gap between the stake hole 1 and the ready-made stake 2 is filled with slag 3 having expandability and solidification. The slag 3 is solidified while expanding.
As a result, the slag 3 expands and solidifies, thereby consolidating the ground around the pile hole 1 and increasing the relative density. As a result, the lateral pressure from the hole wall increases, and the ready-made pile 2 is restrained. And the pile hole 1 are integrated to enhance the vertical supporting force and the horizontal strength.
In this case, the slag 3 should be filled in the vicinity of the expanded bottom portion 11 and the later pile hole 1 should be filled with cement milk, soil cement 5 or the like, or should be completely filled from the expanded bottom portion 11 to the upper portion of the pile hole. Can be.
[0026]
Further, as shown in FIG. 3A, a slag 4 for root compaction is introduced into the lower part of the expanded bottom part 11 so as to have a layer thickness of 1D to 3D of the pile diameter D, and the slag 4 for root compaction is placed on the slag 4. It is also possible to build the above-mentioned knotted concrete pile, whereby the ground under the ready-made pile is solidified, and the vertical supporting force of the foundation pile can be further increased.
In this case, a slag (described later) having expansion and solidification properties to which a solidifying agent such as cement, gypsum, granulated slag, and reduced slag has been added can be used as the slag 4 for root compaction. The lower ground can be hardened to further increase the vertical bearing capacity of the foundation pile.
[0027]
On the other hand, the slag 3 is a slag having expandability and solidification properties, specifically, steelmaking slag (converter slag and / or electric furnace slag (oxidized slag and / or reduced slag). In addition to steelmaking slag that has not been treated, it refers to steelmaking slag that has not lost its expandability, such as steelmaking slag whose expandability has been adjusted by partially performing aging treatment.), Garbage incineration slag, and sludge slag. Species or a mixture of two or more can be used.
In addition, slag having expandability and solidification properties is used alone, and in addition to steelmaking slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, garbage incineration Industrial expandable materials such as crushed glass, waste gypsum, concrete waste, gypsum, quicklime, cement, crushed stone, earth and sand, building materials, artificial materials, and one or more minerals. A slag having a solidifying property and capable of utilizing the expanding property and the solidifying property can be used.
As a result, the slag having expandability and solidification absorbs water and expands and solidifies, so that even when the gap between the pile hole and the pile is narrow, the gap between the pile hole and the pile is filled without forming a uniform cavity. And compressive force can be transmitted to the deep part, the ground around the pile can be easily, statically and securely compacted, and the ground support capacity can be increased. , Can increase the supporting capacity of the pile.
In addition, it is possible to effectively use steelmaking slag, which is industrial waste.
[0028]
In addition, as shown in FIG. 3B, the expanded bottom portion 11 of the pile hole 1 can be excavated to a depth covering substantially the entire length of the knotted concrete pile serving as the lower pile 21.
Thereby, the restraining force of the ready-made pile 2 can be increased, and the vertical bearing capacity and horizontal strength of the foundation pile can be enhanced.
[0029]
As shown in FIG. 3B, the diameter _DH of the pile hole 1 is twice or more, more specifically, two to four times the diameter D of the upper pile 23 (see FIG. 3B). In the embodiment, it can be about three times).
Thereby, by filling the gap between the pile hole 1 and the pile 2 with slag having expandability and solidification properties, the ground around the pile can be easily, statically and more securely compacted. The bearing capacity can be increased, thereby increasing the bearing capacity of the pile.
Further, the required number of intermediate piles can be added depending on the excavation length of the pile hole 1.
[0030]
Further, the intermediate pile 22 has a necessary strength to support the overlying load, and can have a lower bending rigidity than the upper pile 23.
Thereby, the lateral load and displacement received by the upper pile 23 in the upper ground can be absorbed by the bending of the intermediate pile 22.
[0031]
Thus, the construction method of the foundation pile structure and the foundation pile on the supporting ground of this embodiment is that the ready-made knotted concrete pile is disposed as the lower pile 21 buried in the extension part 11. Since a pre-made cylindrical steel pipe pile is provided as the upper pile 23 connected with the intermediate pile 22 while supporting the ground, the upper layer is soft and the lower layer has the supporting force. Directional load and displacement, and furthermore, since a ready-made cylindrical concrete pile is arranged as the intermediate pile 22 connected to the upper part of the lower pile 21, even in the ground where the upper layer is soft and the lower layer has a supporting force, It can be constructed at low cost.
[0032]
【Example】
The gap between the pile hole 1 and the ready-made pile 2 is filled with a slag 3 having expandability and solidification properties, and the slag 3 is expanded and solidified while being expanded, thereby supporting the pile (second limit load: equivalent to 10% of the pile tip diameter). Table 1 shows the results of an in-situ scale experiment conducted to compare the change over time of the load at the time when the pile tip settlement amount occurs with the cement milk commonly used as a filler.
The field-scale experiments performed are as follows.
[0033]
[Field scale experiment]
Ground: Soft ground pile with N value of 2 to 12 and average N value of 6 Type: Concrete knot pile φ440-300 Class A 11m
Pile No. In (1), the ground was excavated and a pile was built, and the gap between the pile hole and the ready-made pile was filled with steelmaking slag having expandability and solidification.
Pile No. In (2), the soil was excavated, a pile was built, and cement milk was injected into the gap between the pile hole and the ready-made pile to form a soil cement layer.
[0034]
[Table 1]

[0035]
As shown in Table 1, pile No. 1 filled with steelmaking slag was used. {Circle around (1)} is a pile No. 1 in which the values of the 3-month curing support force / 1-month curing support force (= 1.27) and the second limit load both formed the soil cement layer. The value of (2) is larger than that of (2), which confirms that the steelmaking slag can be expanded and solidified to increase the pile supporting force.
[0036]
As described above, the foundation pile structure and the method of constructing the foundation pile on the support ground according to the present invention have been described based on the embodiments. However, the present invention is not limited to the description of the embodiments, and does not deviate from the gist thereof. Can be changed as appropriate.
[0037]
【The invention's effect】
According to the foundation pile structure and the construction method of the foundation pile on the support ground of the present invention, since the ready-made knotted concrete pile is arranged as the lower pile buried in the expanded bottom, the pile supporting force is obtained at the expanded bottom. In addition, as an upper pile connected via an intermediate pile, since a cylindrical cylinder having substantially the same diameter as an existing cylindrical concrete pile to be disposed as an intermediate pile and having a bending rigidity greater than that of the cylindrical concrete pile, Even if the upper layer is soft and the lower layer has bearing capacity, it can withstand the lateral load and displacement on the upper layer, and an existing cylindrical concrete pile is arranged as an intermediate pile connected to the upper part of the lower pile. Therefore, even if the upper layer is soft and the lower layer has a supporting force, it can be constructed at low cost.
[0038]
In addition, a ready-made cylindrical concrete pile having substantially the same diameter as the shaft of the lower knotted concrete pile may be provided as an intermediate pile, or a ready-made cylindrical concrete pile having substantially the same diameter as the knot of the lower knotted concrete pile may be provided. By arranging the piles, it is possible to easily and firmly connect the intermediate pile and the lower concrete knotted pile.
[0039]
In addition, by filling the gap between the pile hole and the pile with slag having expandability and solidification properties and solidifying the slag while expanding the slag, the slag expands and solidifies. The soil around the pile hole is compacted and the relative density increases, which increases the lateral pressure from the hole wall, further restrains the ready-made pile, and integrates the ready-made pile with the pile hole to increase its vertical bearing capacity. And horizontal proof stress can be enhanced.
[0040]
In addition, a slag for consolidation is put into the lower part of the expanded bottom part, and the knotted concrete pile is erected on the slag for consolidation, thereby solidifying the ground under the ready-made pile and further increasing the vertical bearing capacity of the foundation pile. Can be enhanced.
[0041]
In addition, by using a slag having expansion and solidification properties to which a solidifying agent is added as a slag for solidification, the ground under the ready-made pile can be solidified, and the vertical bearing capacity of the foundation pile can be further increased.
[0042]
In addition, as slag having expandability and solidification properties, steelmaking slag (converter slag and / or electric furnace slag (oxidized slag and / or reduction slag) is referred to. In particular, here, steel slag not subjected to aging treatment is used. A steelmaking slag which does not lose its expandability, such as steelmaking slag whose expandability has been adjusted by partially performing aging treatment.), Garbage incineration slag, and one or more mixtures of sludge slag are used. In addition, slag having expansion and solidification properties is used alone, and in addition to this, steelmaking slag having lost expansibility, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, Industrial waste such as incineration ash, crushed glass, waste gypsum, concrete waste, etc., building materials such as gypsum, quicklime, cement, crushed stone, earth and sand, clay, etc. , Slag having expandability and solidification absorbs water by using slag having expandability and solidification by mixing one or two or more of artificial materials and minerals. By expanding and solidifying, even when the gap between the pile hole and the pile is narrow, the gap between the pile hole and the pile can be uniformly filled without forming a cavity, and the compressive force is transmitted to the deep layer. The ground around the pile can be easily, statically and securely compacted, and the support of the ground can be increased, thereby increasing the support of the pile.
In addition, it is possible to effectively use steelmaking slag, which is industrial waste.
[0043]
In addition, by excavating the bottom of the pile hole to a depth over substantially the entire length of the noded concrete pile, the restraining force of the pile can be increased, and the vertical bearing capacity and horizontal strength of the ready-made pile can be enhanced. .
[0044]
In addition, by making the intermediate pile have the required strength to support the overlying load and having a lower bending stiffness than the upper pile, the lateral load received by the upper pile on the upper ground can be reduced by the intermediate pile. Can be absorbed by bending.
[Brief description of the drawings]
FIG. 1 shows an embodiment of a foundation pile structure and a method of constructing a foundation pile on a supporting ground according to the present invention, wherein (a) is a cross-sectional view showing a pile hole, and (b) is a pile hole excavating an expanded bottom portion. FIG. 4C is a cross-sectional view showing a state in which a ready-made pile is erected and filled with slag in a pile hole, and FIG. 4D is an explanatory view showing expansion characteristics of the slag in a state where slag is filled in a pile hole.
FIG. 2 shows a foundation pile structure of the present invention, in which (a) is a sectional view showing an embodiment in which a pile diameter of an intermediate pile is substantially equal to a shaft diameter of a lower pile, and (b) and (c) are cross-sectional views of the intermediate pile. It is sectional drawing which shows the Example which made the pile diameter substantially equal to the node diameter of the lower pile.
3A and 3B show a foundation pile structure of the present invention, in which FIG. 3A is a cross-sectional view showing an embodiment in which a slag for consolidation is introduced into a lower portion of a bottom portion, and FIG. It is sectional drawing which shows the Example which was made to excavate to the depth which covers the substantially full length of a concrete stake.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pile hole 11 Expanding bottom part 2 Precast pile 21 Lower pile 22 Intermediate pile 23 Upper pile 3 Slag 4 Slag for rooting 5 Cement milk

Claims

In the foundation pile structure on the support ground where the ready-made pile is buried in the pile hole with the expanded bottom, a ready-made knotted concrete pile is installed as the lower pile buried in the expanded bottom, and the intermediate pile connected to the upper part of the lower pile. A ready-made cylindrical concrete pile is provided as a pile, and a ready-made cylindrical pile having substantially the same diameter as the cylindrical concrete pile and having a greater bending rigidity than the cylindrical concrete pile is provided as an upper pile connected to the upper part of the intermediate pile. The foundation pile structure in the supporting ground characterized by the above.

2. The foundation pile structure in a supporting ground according to claim 1, wherein a ready-made cylindrical concrete pile having substantially the same diameter as the shaft of the lower noded concrete pile is disposed as the intermediate pile.

2. A foundation pile structure in a supporting ground according to claim 1, wherein a ready-made cylindrical concrete pile having substantially the same diameter as a knot of the lower knotted concrete pile is disposed as an intermediate pile.

4. The foundation pile structure in a supporting ground according to claim 1, wherein a gap between the pile hole and the pile is filled with slag having expandability and solidification properties, and the slag is solidified while expanding.

5. A foundation pile on a supporting ground according to claim 1, wherein a slag for consolidation is put into a lower portion of the expanded bottom portion, and the knotted concrete pile is erected on the slag for consolidation. Construction.

6. The foundation pile structure in a supporting ground according to claim 5, wherein a slag having expansion and solidification properties to which a solidifying agent is added is used as the slag for root compaction.

The foundation pile structure in a supporting ground according to claim 4, 5 or 6, wherein the slag having expandability and solidification property is composed of one or a mixture of two or more of steelmaking slag, refuse incineration slag, and sludge slag.

Steel slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, garbage incineration ash, crushed glass, waste gypsum, concrete waste Expansion and solidification of slag that has expansion and solidification properties by mixing one or more of building materials such as gypsum, quicklime, cement, crushed stone, earth and sand, clay, etc., artificial materials and minerals The foundation pile structure in the supporting ground according to claim 4, 5, 6 or 7, wherein:

The foundation in a supporting ground according to claim 1, 2, 3, 4, 5, 6, 7, or 8, wherein the expanded bottom portion of the pile hole is excavated to a depth over substantially the entire length of the knotted concrete pile. Pile structure.

The intermediate pile has a necessary strength to support an overlying load, and has a lower bending rigidity than the upper pile. 10. A foundation pile structure on the support ground according to 9.

In the method of constructing a foundation pile on a supporting ground where a ready-made pile is buried in a pile hole with an expanded bottom, a ready-made noded concrete pile is laid as a lower pile buried in the expanded bottom and connected to the upper part of the lower pile. A ready-made cylindrical concrete pile is disposed as an intermediate pile, and a ready-made cylindrical pile having substantially the same diameter as the cylindrical concrete pile and having a greater bending rigidity than the cylindrical concrete pile is disposed as an upper pile connected to the upper part of the intermediate pile. A method of constructing a foundation pile on a supporting ground, characterized in that:

The method according to claim 11, wherein the gap between the pile hole and the pile is filled with slag having expandability and solidification properties, and the slag is solidified while expanding.

The method for constructing a foundation pile on a supporting ground according to claim 11 or 12, wherein a slag for consolidation is put into a lower portion of the expanded bottom portion, and the knotted concrete pile is built on the slag for consolidation.

14. The method for constructing a foundation pile on a supporting ground according to claim 13, wherein a slag having expansion and solidification properties to which a solidifying agent is added is used as the slag for consolidation.

The construction of a foundation pile on a supporting ground according to claim 12, 13 or 14, wherein the slag having expandability and solidification property is composed of one or a mixture of two or more of steelmaking slag, refuse incineration slag, and sludge slag. Law.

Steel slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, garbage incineration ash, crushed glass, waste gypsum, concrete waste Expansion and solidification of slag which has one or more types of industrial materials such as gypsum, quicklime, cement, crushed stone, earth and sand, clay and other building materials, artificial materials, and minerals. The method for constructing a foundation pile on a supporting ground according to claim 12, 13, 14, or 15, wherein the method can be used.

17. The method for constructing a foundation pile on a supporting ground according to claim 11, wherein an enlarged bottom portion of the pile hole is excavated to a depth extending over substantially the entire length of the knotted concrete pile. .

The intermediate pile has a necessary strength to support the overlying load, and has a lower bending rigidity than the upper pile. 18. The method for constructing a foundation pile on a supporting ground according to 16 or 17.