JP4057873B2

JP4057873B2 - Foundation pile structure on support ground and construction method of foundation pile

Info

Publication number: JP4057873B2
Application number: JP2002288418A
Authority: JP
Inventors: 貞男藪内
Original assignee: Japan Pile Corp
Current assignee: Japan Pile Corp
Priority date: 2002-10-01
Filing date: 2002-10-01
Publication date: 2008-03-05
Anticipated expiration: 2022-10-01
Also published as: JP2004124452A

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、拡底部の下部に固化剤を添加した膨張・固化性を有するスラグからなる根固め用スラグを投入し、該根固め用スラグの上に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、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、拡底部の下部に固化剤を添加した膨張・固化性を有するスラグからなる根固め用スラグを投入し、該根固め用スラグの上に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、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】
そして、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。
【０００９】
さらに、拡底部の下部に固化剤を添加した膨張・固化性を有するスラグからなる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。
【００１０】
また、膨張・固化性を有するスラグに、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。
【００１１】
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。
【００１２】
【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。
【００１３】
図１に、支持地盤における基礎杭構造及び基礎杭の施工法の参考例を示す。
【００１４】
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。
【００１５】
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。
【００１６】
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。
【００１７】
また、図３（ａ）に示す本発明の実施例のように、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。
【００１８】
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。
【００１９】
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。
【００２０】
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。
【００２１】
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。
【００２２】
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。
【００２３】
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。
【００２４】
［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 φ４４０−３００Ａ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。
【００２５】
【表１】

【００２６】
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。
【００２７】
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。
【００２８】
【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、拡底部の下部に固化剤を添加した膨張・固化性を有するスラグからなる根固め用スラグを投入し、該根固め用スラグの上に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。
【００２９】
そして、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。
【００３０】
さらに、拡底部の下部に固化剤を添加した膨張・固化性を有するスラグからなる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。
【００３１】
また、膨張・固化性を有するスラグとして、膨張・固化性を有するスラグに、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。
【図面の簡単な説明】
【図１】支持地盤における基礎杭構造及び基礎杭の施工法の参考例を示し、（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】同基礎杭構造を示し、（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】同基礎杭構造を示し、（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]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a foundation pile structure and a foundation pile construction method in a support ground in which a pile hole having an expanded bottom portion is excavated in a support layer for obtaining a support 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 the supporting force and pulling resistance of a pile, a widened pile having a widened portion at the lower end of the pile is widely known.
In this case, there are two types of bottom-pile piles: one that has a bottom-up portion at the lower end of the cast-in-place pile, and one that has a bottom-up portion 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 An expanded bottom is excavated, and concrete is cast into the expanded bottom to form an expanded pile.
As an expanded pile with ready-made piles, it is generally well known that cement milk is injected into the pile hole and solidified before or after the ready-made piles are buried. in use.
[0003]
[Problems to be solved by the invention]
However, since the construction method of the foundation pile in the above conventional support ground embeds the concrete pile over the entire length of the pile hole, when burying the ready-made pile on the ground where the upper layer is soft and the lower layer has supporting force, Even if the bearing capacity of the pile at the widened part is obtained, there is a problem that the upper part of the concrete pile cannot withstand the lateral load and displacement on the upper ground.
[0004]
In view of the problems of the construction method of the foundation pile in the conventional support ground described above, the present invention obtains the support force of the pile at the bottom expanded portion, and even in the ground where the upper layer is soft and the lower layer has the support force, An object of the present invention is to provide a foundation pile structure and a foundation pile construction method in a supporting ground that can withstand lateral loads and displacements of the earth and can be constructed at low cost.
[0005]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the foundation pile structure in the support ground of the present invention is an expansion / addition of a solidifying agent added to the lower part of the bottom expansion part in the foundation pile structure in the support ground in which a ready-made pile is embedded in a pile hole having the bottom expansion part. A solidifying slag made of solidified slag is thrown in, and a prefabricated knotted concrete pile is installed as a lower pile buried in the expanded bottom on the rooting slag, and connected to the upper part of the lower pile As an intermediate pile, a pre-made cylindrical concrete pile is arranged, and as an upper pile connected to the upper part of the intermediate pile, a pre-made cylindrical pile having substantially the same diameter as that of the cylindrical concrete pile and having a larger bending rigidity than the cylindrical concrete pile is arranged. It is characterized by filling the gap between the pile hole and the pile with slag having expansion / solidification properties, and solidifying the slag while expanding it.
[0006]
Moreover, in order to achieve the same purpose, the foundation pile construction method in the support ground of the present invention is solidified in the lower part of the bottom expansion portion in the foundation pile construction method in the support ground in which the ready-made pile is buried in the pile hole having the bottom expansion portion. Slag for solidification consisting of slag with expansion and solidification added with an agent is added, and a pre-made knotted concrete pile is disposed as a lower pile buried in the expanded bottom on the root slag , A ready-made cylindrical concrete pile is arranged as an intermediate pile connected to the upper part of the lower pile, and the upper pile connected to the upper part of the intermediate pile is substantially the same diameter as that of the cylindrical concrete pile, and has a bending rigidity higher than that of the cylindrical concrete pile. A large ready-made cylindrical pile is disposed, and a gap between the pile hole and the pile is filled with slag having expansion / solidification properties, and the slag is solidified while being expanded.
[0007]
The foundation pile structure and foundation pile construction method in this support ground is to arrange a ready-made knotted concrete pile as the lower pile buried in the expanded bottom part. As the upper pile connected through the intermediate pile, the prefabricated cylindrical pile having the same diameter as the intermediate pile and the bending rigidity larger than that of the cylindrical concrete pile is arranged. Even in the ground where the lower layer has bearing capacity, it can withstand lateral loads and displacements in the upper layer ground, and in addition, a ready-made cylindrical concrete pile is arranged as an intermediate pile connected to the upper part of the lower pile Even the ground where the upper layer is soft and the lower layer has supporting ability can be constructed at low cost.
[0008]
In addition, the slag expands and solidifies by filling the gap between the pile hole and the pile with slag having expandability and solidification, and solidifying while expanding the slag, so that the slag restrains the ready-made pile. Thus, the ground around the pile hole is compacted, and the relative density increases, thereby increasing the lateral pressure from the hole wall and further restraining the ready-made pile, and the ready-made pile and the pile hole are integrated into the vertical bearing force. And the horizontal proof stress can be enhanced.
[0009]
Furthermore, by introducing a solidifying slag made of slag having expansion / solidification properties with a solidifying agent added to the lower part of the expanded bottom portion and building the knotted concrete pile on the rooting slag , The lower ground can be hardened and the vertical bearing capacity of the foundation pile can be further increased.
[0010]
Furthermore, the slag having an inflatable-hardenable, steel slag which has lost expandable, blast furnace slag, ferro alloy slag, granulated slag, copper smelting slag, red mud, fly ash, refuse incineration ash, glass crushed waste gypsum, Industrial waste such as concrete waste, gypsum, quicklime, cement, crushed stone, earth and sand, building materials such as clay, clay, clay, etc. What can utilize property and solidification property can be used.
[0011]
As a result, the slag with expansion and solidification absorbs water, 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. It is possible to transmit compressive force to the deep layer, and the ground around the pile can be easily, statically and securely compacted. , Can increase the bearing capacity of the pile.
Moreover, effective use of steelmaking slag etc. which are industrial waste can be aimed at.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the foundation pile structure and the foundation pile construction method in the supporting ground of the present invention will be described based on the drawings.
[0013]
FIG. 1 shows a reference example of a foundation pile structure and a foundation pile construction method in a supporting ground .
[0014]
This foundation pile structure embeds the ready-made pile 2 in the pile hole 1 having the expanded bottom portion 11, arranges the ready-made knotted concrete pile as the lower pile 21 embedded in the expanded bottom portion 11, and lower pile 21. As the intermediate pile 22 connected to the upper portion of the intermediate pile 22, a ready-made cylindrical concrete pile having a diameter substantially the same as the shaft diameter of the knotted concrete pile is disposed, and the upper pile 23 connected to the upper portion of the intermediate pile 22 is used as the intermediate pile 22. A prefabricated cylindrical pile such as a steel pipe pile, an SC pile, a PRC pile or the like having a substantially the same diameter as that of the cylindrical concrete pile and having a bending rigidity greater than that of the cylindrical concrete pile is disposed.
[0015]
In this case, as shown in FIG. 1 and FIG. 2 (a), as the intermediate pile 22, in addition to using a ready-made cylindrical concrete pile having the same diameter as the shaft portion of the lower nodeed concrete pile 21, FIG. ) And (c), as shown in FIG. 2 (b), the ready-made cylindrical concrete pile having the same diameter as the joint of the lower jointed concrete pile 21 (the connection between the lower pile 21 and the intermediate pile 22 is shown in FIG. As shown in FIG. 2 (c), the lower pile 21 is a concrete pile with a node whose upper end is formed to have a large diameter substantially the same as that of the node, or a tapered joint 24 as shown in FIG. Can be used.) Can be provided. Moreover, although not shown in figure, the connection of the intermediate | middle pile 22 and the upper pile 23 can make the diameter of the upper pile 23 large diameter similarly to FIG.2 (c).
Thereby, the axial diameter of the intermediate pile 22 and the upper pile 23 can be enlarged, and horizontal proof stress can be strengthened.
[0016]
As shown in Fig. 1 (a), the foundation pile is constructed by excavating the ground to the ground that can support the upper structure with an auger head (not shown) as shown in Fig. 1 (a). Next, the bottom of the excavated pile hole 1 is expanded to form the expanded bottom 11.
Next, as shown in FIGS. 1 (c) and 1 (d), the ready-made pile 2 is built at the bottom of the pile hole 1, and the gap between the pile hole 1 and the ready-made pile 2 is filled with slag 3 having expansion / solidification properties. The slag 3 is solidified while being expanded.
Thereby, when the slag 3 expands and solidifies, the ground around the pile hole 1 is compacted and the relative density increases, thereby increasing the lateral pressure from the hole wall and restraining the ready-made pile 2, and the ready-made pile 2 And the pile hole 1 can be integrated to enhance the vertical support force and horizontal proof stress.
In this case, the slag 3 is filled in the vicinity of the expanded bottom portion 11 and the subsequent pile hole 1 is filled with cement milk, soil cement 5 or the like, or is filled from the expanded bottom portion 11 to the top of the pile hole. Can do.
[0017]
Moreover, like the Example of this invention shown to Fig.3 (a), the slug 4 for root hardening is thrown into the lower part of the bottom enlarged part 11 so that it may become the layer thickness of 1D-3D of the pile diameter D, and this root It is also possible to build the knotted concrete pile on the slag 4 for hardening, thereby solidifying the lower ground of the ready-made pile and further enhancing the vertical supporting force of the foundation pile. .
In this case, as the slag 4 for solidifying, slag (which will be described later) having expandability / solidification properties to which a solidifying agent such as cement, gypsum, granulated slag, or reduced slag is added can be used. The lower ground can be hardened and the vertical bearing capacity of the foundation pile can be further increased.
[0018]
On the other hand, the slag 3 refers to a slag having expandability and solidification properties, specifically, a steelmaking slag (converter slag and / or electric furnace slag (oxidized slag and / or reduced slag), and particularly here, aging. In addition to steelmaking slag that has not been treated, this refers to steelmaking slag that has not lost its expansibility, such as steelmaking slag that has been subjected to partial aging treatment to adjust its expansibility.), Waste incineration slag, sludge slag A seed or a mixture of two or more can be used.
In addition, slag with expandability and solidification is used alone, as well as steelmaking slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, and garbage incineration ash that have lost expansibility. , Expansive mixture of industrial waste such as crushed glass, waste gypsum, concrete waste, gypsum, quicklime, cement, crushed stone, earth and sand, clay, etc., artificial materials and minerals And what can utilize the expansibility and solidification property of slag which has solidification property can be used.
As a result, the slag with expansion and solidification absorbs water, 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. It is possible to transmit compressive force to the deep layer, and the ground around the pile can be easily, statically and securely compacted. , Can increase the bearing capacity of the pile.
Moreover, effective use of steelmaking slag etc. which are industrial waste can be aimed at.
[0019]
Moreover, as shown in FIG.3 (b), the bottom expansion part 11 of the pile hole 1 can be excavated to the depth over the substantially full length of the nodal concrete pile which is the lower pile 21. FIG.
Thereby, the restraining force of the ready-made pile 2 can be increased and the vertical supporting force and horizontal proof stress of a foundation pile can be strengthened.
[0020]
Moreover, as shown in FIG.3 (b), the diameter _DH of the pile hole 1 is 2 times or more of the diameter D of the upper pile 23, More specifically, it is 2-4 times (shown in FIG.3 (b)). In the example , it can be about 3 times).
Thus, by filling the gap between the pile hole 1 and the pile 2 with slag having expansion / solidification properties, the ground around the pile can be easily, statically and more reliably compacted. The supporting force can be increased, and thereby the supporting force of the pile can be increased.
Moreover, the required number of intermediate piles can be added by the excavation length of the pile hole 1.
[0021]
In addition, the intermediate pile 22 has a necessary proof strength to support the loading load, and can have a bending rigidity smaller than that of the upper pile 23.
Thereby, the load and displacement of the horizontal direction which the upper pile 23 received by the upper ground can be absorbed when this intermediate pile 22 bends.
[0022]
Thus, the foundation pile structure and the foundation pile construction method in the supporting ground of this embodiment is because the ready-made knotted concrete pile is disposed as the lower pile 21 buried in the expanded bottom portion 11, so Since a pre-made cylindrical steel pipe pile is disposed as the upper pile 23 connected via the intermediate pile 22, the bearing strength is obtained, and even in the ground where the upper layer is soft and the lower layer has the supporting force, In addition, since a ready-made cylindrical concrete pile is disposed as an intermediate pile 22 connected to the upper portion of the lower pile 21, the upper layer is soft and the lower layer has a supporting force. Can be constructed at low cost.
[0023]
Pile bearing capacity (second limit load: equivalent to 10% of pile tip diameter) by filling the gap between the pile hole 1 and the ready-made pile 2 with slag 3 having expandability and solidification, and solidifying the slag 3 while expanding Table 1 shows the results of a field-scale experiment conducted in order to compare the time-dependent change of the load when the pile tip settlement amount of the piles) is compared with cement milk generally used as a filler.
The field-scale experiments that were conducted are as follows.
[0024]
[Field-scale experiment]
Ground: Soft ground with N value 2-12, average N value 6 Pile type: Concrete joint pile φ440-300 A type 11m
Pile No. No. 1 excavated the original ground and built a pile, and filled the steelmaking slag having expansion / solidification properties in the gap between the pile hole and the ready-made pile.
Pile No. 2 excavated the ground and built a pile, and poured cement milk into the gap between the pile hole and the ready-made pile to form a soil cement layer.
[0025]
[Table 1]

[0026]
As shown in Table 1, pile No. 1 filled with steelmaking slag was used. No. 1 is a pile No. 1 in which a soil cement layer is formed in both the three-month curing support capacity / one-month curing support capacity (= 1.27) and the second limit load value. The value larger than that of 2 was shown, and it was confirmed that the steelmaking slag expands and solidifies so that the supporting force of the pile can be increased.
[0027]
As mentioned above, although the foundation pile structure in the support ground of this invention and the construction method of a foundation pile were demonstrated based on the Example, this invention is not limited to description of this Example, The range which does not deviate from the summary It is possible to change as appropriate.
[0028]
【The invention's effect】
According to the foundation pile structure and the foundation pile construction method in the support ground of the present invention, a root-solidifying slag made of slag having expansion / solidification property with a solidifying agent added to the lower part of the bottom-expanded portion is introduced, Since a ready-made knotted concrete pile is placed as a lower pile buried in the expanded bottom on the slag , the pile support capacity is obtained at the expanded bottom, and as an upper pile connected via the intermediate pile, Since the prefabricated cylindrical pile having the same diameter as the prefabricated cylindrical concrete pile to be arranged as the pile and having a higher bending rigidity than the cylindrical concrete pile is disposed, even in the ground where the upper layer is soft and the lower layer has supporting force, It can withstand lateral loads and displacements on the ground, and since a pre-made cylindrical concrete pile is placed as an intermediate pile connected to the upper part of the lower pile, the upper layer is soft and the lower layer has bearing capacity On the ground It may be applied at a low cost.
[0029]
In addition, the slag expands and solidifies by filling the gap between the pile hole and the pile with slag having expandability and solidification, and solidifying while expanding the slag, so that the slag restrains the ready-made pile. Thus, the ground around the pile hole is compacted, and the relative density increases, thereby increasing the lateral pressure from the hole wall and further restraining the ready-made pile, and the ready-made pile and the pile hole are integrated into the vertical bearing force. And the horizontal proof stress can be enhanced.
[0030]
Furthermore, by introducing a solidifying slag made of slag having expansion / solidification properties with a solidifying agent added to the lower part of the expanded bottom portion and building the knotted concrete pile on the rooting slag, The lower ground can be hardened and the vertical bearing capacity of the foundation pile can be further increased.
[0031]
In addition, as slag with expansion / solidification properties, steel slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, and garbage incineration have lost their expansion properties. Industrial waste such as ash, crushed glass, waste gypsum, concrete waste, gypsum, quicklime, cement, crushed stone, earth and sand, clay, and other building materials, artificial materials, and one or more of minerals mixed to expand When the slag having expandability and solidification is used, the slag having expansion and solidification absorbs water, expands and solidifies, and the gap between the pile hole and the pile is narrow. However, the gap between the pile hole and the pile can be filled without forming a uniform cavity, and the compressive force can be transmitted to the deep layer part, so that the ground around the pile can be easily Manner, and can be solidified reliably tightened, enhancing the supporting force of the ground, which makes it possible to increase the bearing capacity of the pile.
Moreover, effective use of steelmaking slag etc. which are industrial waste can be aimed at.
[Brief description of the drawings]
FIG. 1 shows a reference example of a foundation pile structure and foundation pile construction method in a supporting ground , (a) is a sectional view showing a pile hole, (b) is a sectional view showing a pile hole excavated from the bottom, c) is a cross-sectional view showing a state in which a ready-made pile is built in the pile hole and the slag is filled, and (d) is an explanatory diagram showing an expansion characteristic of the slag in a state where the slag is filled in the pile hole.
FIG. 2 shows the same foundation pile structure, (a) is a cross-sectional view showing an embodiment in which the pile diameter of the intermediate pile is substantially equal to the shaft diameter of the lower pile, and (b), (c) are pile diameters of the intermediate pile. It is sectional drawing which shows the Example which made substantially equal to the node diameter of a lower pile.
FIG. 3 shows the same foundation pile structure, (a) is a cross-sectional view showing an embodiment in which slag for root consolidation is put into the lower part of the expanded bottom part, and (b) is a concrete with knots at the expanded part of the pile hole. It is sectional drawing which shows the example made to excavate to the depth over the substantially full length of a pile.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pile hole 11 Expanded bottom part 2 Ready-made pile 21 Lower pile 22 Intermediate pile 23 Upper pile 3 Slag 4 Slag for root consolidation 5 Cement milk

Claims

In the foundation pile structure in the support ground where the prefabricated pile is buried in the pile hole having the expanded bottom part, the slag for solidification consisting of slag having expansion and solidification properties with the addition of a solidifying agent is added to the lower part of the expanded bottom part, A prefabricated jointed concrete pile is placed as a lower pile buried in the expanded bottom on the slag for construction, and a prefabricated cylindrical concrete pile is placed as an intermediate pile connected to the upper part of the lower pile. As an upper pile connected to the upper part, a prefabricated cylindrical pile having substantially the same diameter as that of the cylindrical concrete pile and having a higher bending rigidity than the cylindrical concrete pile is disposed, and a slag having expansion / solidification properties is provided in the gap between the pile hole and the pile. A foundation pile structure in a supporting ground, which is filled and solidified while expanding the slag.

Steel slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, garbage incineration ash, glass crushed material, waste gypsum, concrete waste material that has lost its expandability to slag with expandability and solidification Expansion and solidification of slag with expansion and solidification properties, such as industrial waste such as gypsum, quicklime, cement, crushed stone, earth and sand, clay, and other building materials, artificial materials, and minerals The foundation pile structure in the supporting ground according to claim 1, wherein

In the construction method of the foundation pile in the supporting ground in which the ready-made pile is buried in the pile hole having the expanded bottom part, the slag for solidifying composed of the slag having expansion / solidification property to which the solidifying agent is added is added to the lower part of the expanded bottom part, A ready-made knotted concrete pile is placed as a lower pile buried in the expanded bottom on the root slag, and a ready-made cylindrical concrete pile is placed as an intermediate pile connected to the upper part of the lower pile. As an upper pile connected to the upper part of the pile, a prefabricated cylindrical pile that is substantially the same diameter as the cylindrical concrete pile and has a higher bending rigidity than the cylindrical concrete pile is disposed, and the gap between the pile hole and the pile has expansion and solidification properties. A construction method of a foundation pile on a supporting ground, characterized by filling slag and solidifying the slag while expanding.

Steel slag, blast furnace slag, ferroalloy slag, granulated slag, copper smelting slag, red mud, fly ash, garbage incineration ash, glass crushed material, waste gypsum, concrete waste material that has lost its expandability to slag with expandability and solidification Expansion and solidification of slag with expansion and solidification properties, such as industrial waste such as gypsum, quicklime, cement, crushed stone, earth and sand, clay, and other building materials, artificial materials, and minerals The construction method of the foundation pile in the support ground of Claim 3 characterized by the above-mentioned.