JP4617604B2

JP4617604B2 - Threaded pile and method of construction

Info

Publication number: JP4617604B2
Application number: JP2001159266A
Authority: JP
Inventors: 正宏林; 和臣市川; 玄森
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2001-05-28
Filing date: 2001-05-28
Publication date: 2011-01-26
Anticipated expiration: 2021-05-28
Also published as: JP2002348863A

Description

【０００１】
【発明の属する技術分野】
本発明は、ねじ込み杭及びねじ込み杭の施工方法に係り、さらに詳しくは、少なくとも先端部又はその近傍に翼を取付けた杭に回転力を与えることにより、杭を地中に埋設するようにしたねじ込み杭及びねじ込み杭の施工方法に関するものである。
【０００２】
【従来の技術】
杭の先端部や側面に翼状板を取付けて、地上に設置した施工機械を用いて回転力を与えることにより、翼状板の木ねじ作用により地中に埋設するねじ込み杭は、従来から種々提案されており、低振動、低騒音、無排土で施工できると共に、埋設後は翼状板の面積を利用して大きな先端支持力が得られるため土木、建築の分野で実用化されている。以下、本発明に関連すると思われる従来技術について説明する。
【０００３】
特公平２−６２６４８号公報に記載された鋼管杭の埋設工法は、鋼管製の杭本体の下端に底板を固設し、該底板に掘削刃を設けると共に、杭本体の下端部外周面に杭本体の外径のほぼ２倍強の外径を有する翼幅の大きな杭ネジ込み用の螺旋翼を、ほぼ一巻きにわたり突設した鋼管杭を、軟弱地盤にネジ込むように回転させながら地中に押圧し、下端の掘削刃によって杭本体先端の土砂を掘削軟化させて、杭側面の未掘削土砂中に螺旋翼を食い込ませて、土の耐力を反力として杭体を回転推進しつつ、掘削軟化した土砂を杭側面に押出し圧縮し、無排土で地中に杭体をネジ込んでゆくようにしたものである（従来技術１）。
【０００４】
また、特開２０００−１１０１６２号公報に記載された鋼管杭は、鋼管杭の下方が太径のテーパ型鋼管を用いて、杭径の最大径に準拠する許容根入れ長を大きくすることにより、杭の材料費をはじめとする埋設コストを引き下げるとともに、テーパ鋼管の下端に錐体を固着し、その上方の鋼管側面部に螺旋翼を取り付け、その螺旋翼は回転力を推力に変換するとともに、支持力を増大させるようにしたものである（従来技術２）。
【０００５】
さらに、特開２０００−１１０１６０号公報に記載された拡底鋼管杭は、中掘工法で地盤の掘削及び拡底鋼管杭の沈設を行い、拡底部を根固め部に定着させ、拡径部の内径とほぼ等しい径に拡径可能な付着防止翼により連結部と拡径部との間の隅角部の内側に侵入する粘性土やスライムなどの付着を防止し、高い先端支持力を確保するようにしたものである（従来技術３）。
【０００６】
【発明が解決しようとする課題】
従来技術１及び２の鋼管杭は、施工機械で杭頭部にトルクを与えることにより地盤中にねじ込まれ、埋設される。このような螺旋翼を有する鋼管杭は、杭体か螺旋翼の張り出しが大きくなると、施工時に大きな抵抗が作用し、大きなトルクが必要になる。また、供用時には螺旋翼に作用する地盤反力により大きな曲げモーメントが杭体に作用する。このため、杭体は、施工時には大きなトルクに耐えられる肉厚又は強度の大きなものが必要であり、供用時には杭体の肉厚又は強度を大きなものにするか、あるいは螺旋翼の板厚を相当厚いものにする必要があり、不経済である。
【０００７】
従来技術３の鋼管杭は、先端部を拡底化することにより大きな先端支持力を確保することができる。しかし、杭体に翼が設けられていないため、施工にあたっては中掘工法を採用しなければならず、施工が面倒であるばかりでなく、掘削土を地上に排出するためこれを処理しなければならない。また、拡底した鋼管径分の支持力しか確保できない。
【０００８】
本発明は、上記の問題点に鑑みてなされたもので、以下の課題を解決したねじ込み杭及びねじ込み杭の施工方法を提供することを目的としたものである。
（１）杭先端部を拡径し、翼を設けることにより小さな杭体径で大きな先端支持力を得ること。
（２）杭本体からの翼の張り出し長を短かくすることにより曲げの影響を少なくし、翼及び杭本体の板厚を薄くすることにより、経済的な設計を可能にすること。
（３）オーガーを併用して施工する場合、オーガーの挿入及び回収が容易であること。
【０００９】
【課題を解決するための手段】
本発明は、翼を設けた杭体を回転し、該杭体を前記翼の作用により地中に貫入するねじ込み杭において、前記杭体の先端部に、その下端部の内径が前記杭体の内径よりも大径の筒状体からなる拡径部を設け、該拡径部を、前記杭体の外径より大径で翼状に形成された継手部材を介して前記杭体の先端部に接合し、少なくとも前記拡径部の先端部又はその近傍に翼を設けたものである。
【００１２】
上記のねじ込み杭において、翼を拡径部の内壁に接合した。
【００１３】
本発明に係るねじ込み杭の施工方法は、翼及び継手部材に中央開口部を有する上記のねじ込み杭内にオーガーを挿入してそのオーガーヘッドを杭先端部から突出させ、該オーガーと前記翼の作用によりねじ込み杭を地中に貫入するようにしたものである。
【００１４】
上記のねじ込み杭の施工方法において、オーガーの軸方向に貫通穴を設けると共にオーガーヘッドに噴出口を設け、前記貫通穴から硬化性流動物を圧送して前記噴出口から噴出させるようにした。
【００１５】
【発明の実施の形態】
［実施の形態１］
図１は本発明の実施の形態１に係るねじ込み杭の斜視図、図２は図１の模式的縦断面図である。
両図において、１はねじ込み杭で、３は鋼管からなる杭体、４は鋼板を曲げ加工してなり杭体３の先端部に溶接により接合されたテーパー状の拡径部で、これら杭体３と拡径部４とにより杭本体２を構成する。６は拡径部４の先端部に溶接により接合された翼である。
【００１６】
拡径部４は、上端部の外径が杭体３の外径とほぼ等しく、下部になるにしたがって拡径されて截頭円錐状に形成されており、先端部には例えば螺旋状に切除された取付部５が設けられ、この取付部５に、例えばドーナツ状の鋼板を曲げ加工した螺旋状の翼６を溶接により接合したものである。
【００１７】
拡径部４の拡径角度θは、発明者らの実験結果によれば５°〜２０°程度が望ましく、このように構成することにより、拡径部４を形成する鋼板の板厚を、杭体３を構成する鋼管の板厚とほぼ等しいか若干厚めにする程度でよい。拡径角度θが大きい場合は、拡径部４の板厚を大きくすれば、荷重伝達の問題に対処することができる。
また、拡径部４の長さは、杭体３の外径や地盤の状態などによって異なるが、発明者らの実験の結果によれば、杭体３の外径の０．５〜５倍程度が望ましい。
【００１８】
翼６の外径は、杭体３や拡径部４の下端部の外径、あるいは地盤の状態などによって異なるが、一般に杭体３の外径の１．５〜３．５倍程度が望ましく、また、拡径部４の取付部５に接合した状態における外方への張り出し長さ（幅）と、内方への張り出し長さ（幅）とをほぼ等しくすることが望ましい。これにより、基礎杭として供用時に、翼６に作用する地盤反力がバランスして、拡径部４に作用する曲げモーメントを軽減することができる。なお、翼６の拡径部４からの張り出し長さは、杭体３の外径の２０％程度であれば、翼６の推進力により杭体３を地中に貫入することができる。
【００１９】
上記のように構成した本実施の形態に係るねじ込み杭１は、その杭頭部又は杭本体２の上部胴部を施工機械に設けたモータに装着し、このモータによりねじ込み杭を回転させることにより、翼６の木ねじ作用により無排土、低振動、低騒音で地中に貫入される。
このとき、翼６の下方にある土砂は翼により掘削軟化され、翼６のすき間８を通過して杭本体２の外周に移動して圧縮され、また、翼６の中央開口部７から杭本体２内にも取り込まれる。杭本体２の外周に移動した土砂は、施工中は翼６により軟化されるため摩擦抵抗が少なく、ねじ込み杭１をスムーズに貫入することができる。そして、時間の経過と共に地盤強度が回復し、基礎杭として供用時には大きな周面摩擦力が発揮され、また、翼６により大きな支持力を得ることができる。
【００２０】
本実施の形態によれば、杭体２の外径に比べて大きな外径の翼６を設けても、拡径部４の外周からの張り出し長（幅）が短いため、施工に際して地盤の抵抗が小さく、このため、ねじ込み杭を小さいトルクで地中に貫入することができる。また、これにより、拡径部４の板厚を杭体２の板厚とほぼ等しいか少し厚くするだけでよく、翼６の板厚も薄くできるのでコストを低減することができ、経済的である。
さらに、翼６の拡径部４の内外への張り出し長（幅）をほぼ等しくすれば、拡径部４に作用する曲げモーメントを小さくすることができるので、上記のトルクの低減と相俟って、拡径部４及び翼６の板厚をより薄くすることができる。
【００２１】
本実施の形態に係るねじ込み杭は、翼６の中心部に開口部７が設けられているので、施工時に杭本体２内に土砂が侵入する。施工中に翼６が硬い支持層に到達したときは、先端部は閉塞状態となって貫入されるが、杭体３の径が大きくなったり（したがって、翼６の開口部７が大きい）、軟かい地盤の場合には先端閉塞効果が得られないおそれがある。このような場合には、先端閉塞効果を促すために、拡径部４内に板や突起物を設けてもよい（以下の実施の形態においても同様である）。
【００２２】
上記の説明では、拡径部４の先端部を螺旋状に切除して取付部５を形成し、この取付部に１枚の螺旋状の翼６を溶接により接合した場合を示したが、螺旋状の翼６を複数に分割して取付部５に接合してもよい。また、螺旋状の翼６に代えて、円形鋼板、楕円形鋼板、四角形鋼板又はドーナツ状の鋼板を複数に分割した平板状の翼を接合するなど、地中への推進力が得られるものであれば、どのような形状又は構造の翼であってもよい（以下の実施の形態においても同様である）。
【００２３】
さらに、中心部に開口部７を有する開放型の翼６を用いた場合を示したが、拡径部４の先端開口部を閉塞する閉塞型の翼を用いてもよく、あるいは他の部材で先端開口部を閉塞してもよい。さらに、翼又は他の部材で拡径部４の先端開口部を部分的に閉塞し、杭体２内への土砂の侵入を調整するようにしてもよい。このように拡径部４の先端開口部の大きさは、適宜設定することができる。また、翼に貫入性を向上させるための掘削補助刃を設けてもよい。また、翼を拡径部４の先端部に設けた場合を示したが、拡径部４の先端部と外周、拡径部の先端部と杭体３の外周、あるいは拡径部４と杭体３の外周若しくはいずれか一方に設けるなど、翼の取付位置は適宜選択することができる（以下の実施の形態においても同様である）。
【００２４】
［実施の形態２］
図３は本発明の実施の形態２に係るねじ込み杭の模式的縦断面図である。なお、実施の形態１と同じ部分にはこれと同じ符号を付し、説明を省略する。
本実施の形態は、実施の形態１のテーパー状の拡径部４に代えて、杭体３の外径より大径の鋼管等からなる円筒状の筒状体によって拡径部４ａを形成し、継手部材９を介して杭体３に接合し、杭本体２を構成したものである。
【００２５】
拡径部４ａは、外径が杭体３の外径の１．１〜２．５倍程度で、板厚が杭体３の板厚とほぼ同じか若干厚い鋼管からなり、その長さは、実施の形態１の場合に準じて設定される。そして、拡径部４ａの先端部を実施の形態１の場合と同様に螺旋状に切除して取付部５を設け、この取付部５に杭体３の外径の１．５〜３．５倍程度の螺旋状の翼６を溶接により接合したものである。
【００２６】
継手部材９はその内径が杭体３の内径とほぼ等しく、外径が拡径部４ａの外径とほぼ等しいドーナツ状の鋼板からなり、上面が杭体３の先端部に溶接により接合され、下面に拡径部４ａの上端部が溶接により接合される。なお、継手部材９の板厚は、杭体３の外径や作用する鉛直荷重によって異なるため、数値計算によって求める。
上記の説明では、継手部材９をドーナツ状の鋼板で構成した場合を示したが、外径が拡径部４ａとほぼ等しく中心部に開口部のない円板状の鋼板で構成してもよく、あるいは拡径部４ａを断面楕円形の筒状体で構成し、楕円状の鋼板からなる継手部材により杭体３に接合してもよい。
本実施の形態に係るねじ込み杭の施工方法及び作用効果は、実施の形態１の場合とほぼ同様である。
【００２７】
［実施の形態３］
図４は本発明の実施の形態３に係るねじ込み杭の模式的縦断面図である。なお、実施の形態２と同じ部分にはこれと同じ符号を付し、説明を省略する。
本実施の形態は、実施の形態２のドーナツ状、円板状又は楕円状の鋼板からなる継手部材９に代えて、翼により継手部材９ａを構成したものである。
【００２８】
すなわち、杭体３の先端部を螺旋状に切除して取付部３ａを形成すると共に、拡径部４ａの上端部を螺旋状に切除して取付部５ａを形成する。そして、内径が杭体３の内径とほぼ等しく、外径が拡径部４ａの外径より大きいドーナツ状の鋼板を螺旋状に曲げ加工してなる螺旋翼状の継手部材９ａを、杭体３の取付部３ａに溶接により接合すると共に、その下面に、拡径部４の取付部５ａを溶接により接合したものである。なお、継手部材９ａは翼６の外径より大きくてもあるいは小さくてもよく、大きければ主として支持力に寄与し、小さければ主として推進に寄与する。また、翼状の継手部材９ａは螺旋翼に限定するものではなく、前述の翼６の場合と同様に適宜形状又は構造の翼を用いることができる。
【００２９】
本実施の形態の施工方法及び作用、効果は、実施の形態２の場合とほぼ同様であるが、継手部材９ａを翼状に形成したので、施工の際のねじ込み杭の推進力、供用時の支持力に寄与することができる。
【００３０】
［実施の形態４］
図５は本発明の実施の形態４に係るねじ込み杭の模式的縦断面図である。
本実施の形態は、実施の形態１において、テーパー状の拡径部４の先端部に設けた螺旋状の切除部５及び翼６を省略し、拡径部４の内壁に例えば螺旋状の翼６ａを溶接により接合したものである。
【００３１】
本実施の形態における施工方法、作用効果は実施の形態１の場合とほぼ同様であり、翼６ａは施工時にねじ込み杭の推進力として寄与し、供用時には支持体として寄与する。
本実施の形態においても、拡径部４の先端部あるいは拡径部４や杭体３の外周に翼を設けてもよく、これにより地中への推進力及び支持力をさらに向上させることができる。なお、この場合、拡径部４の内壁に設けた翼６ａをねじ込み杭１の貫入回転方向と逆向きに取付ければ、杭本体２内への土砂の侵入を抑制し、先端開口部の閉塞効果を得ることができる。
本実施の形態は、実施の形態２，３にも実施することができる。
【００３２】
【実施例】
実施の形態１のねじ込み杭として、外径５００ｍｍ、板厚１２ｍｍ、長さ２０ｍの杭体３の先端部に、上端部の外径５００ｍｍ、下端部の外径８００ｍｍ（拡径角度θ：１０°）、板厚１２ｍｍ、長さ１ｍで、先端部に角度１５°で螺旋状に切除した取付部５を有する拡径部４の上端部を溶接により接合した。そして、この取付部５に、外径１０００ｍｍ、内径５００ｍｍ、板厚３０ｍｍのドーナツ状の鋼板の１か所を半径方向に切断して螺旋状に曲げ加工して螺旋状に形成した翼６を溶接により接合して製作した。
【００３３】
施工する地盤は、２０ｍまでは比較的軟かい砂層で、それ以深はＮ値５０以上の砂礫層であった。
このような地盤に、施工機械により上記のねじ込み杭に回転力を与えて貫入したところ、通常のねじ込み杭と変らない効率で施工することができ、貫入後引き抜いて点検したところ、翼の変形その他異常は全くみられなかった。
【００３４】
［実施の形態５］
図６は本発明の実施の形態５に係るねじ込み杭の施工方法の説明図である。なお、実施の形態１と同じ部分にはこれと同じ符号を付し、説明を省略する。
図において、１は拡径部４に開放型の翼６を設けたねじ込み杭、１０はねじ込み杭１内に挿入されたオーガーで、１１はオーガーヘッド、１２はスパイラル羽根である。１５は地上に設置した施工機械（図示せず）に設けられたモータで、互いに反対方向に回転する２個の回転軸（外軸１６と内軸１７）を備えている。
【００３５】
次に、上記のように構成した本実施の形態の施工方法について説明する。先ず、ねじ込み杭１内に、ねじ込み杭１より若干長いオーガー１０を挿入し、オーガーヘッド１１を杭先端部から下方に突出させる。そして、ねじ込み杭１の杭頭部をモータ１５の外軸１６に連結し、オーガー１０の頭部を内軸１７に連結する。なお、オーガーヘッド１１は、その外径が杭体３の内径より若干小さいもの、又は翼６の中央開口部７から下方に突出したのち拡径されるものが用いられる。この場合においても、オーガーヘッド１１の外径は、翼６の外径より小さいことが望ましい。
【００３６】
ついで、モータ１５により、例えばねじ込み杭１を正方向に、オーガー１０を逆方向に回転させる。これにより、オーガーヘッド１１がねじ込み杭１に先行して先端部近傍の地盤を掘削軟化し、ねじ込み杭１は翼６の木ねじ作用により地中に貫入される。このとき、ねじ込み杭１の先端部近傍の土砂は、翼６のすき間８を通って上方の杭本体２の外周に移動し、一部の土砂は翼６の開口部７からオーガー１０のスパイラル羽根１２により杭本体２内に取り込まれる。そして、杭先端部が支持層に達したときは、ねじ込み杭１をモータ１５から外し、ねじ込み杭１を地中に残置した状態でオーガー１０を反対方向に回転させながらモータ１５を上昇させれば、オーガー１０はねじ込み杭１から引き抜かれ、ねじ込み杭は地中に埋設されて施工は終了する。
【００３７】
オーガー１０により杭本体２内に取り込まれる土砂の量は、翼６の中央の開口部７の大きさやオーガーヘッド１１の寸法、形状などによって異なるため、これらを調整することにより土砂が杭本体２から溢れないようにする。なお、オーガー１０の回転方向と逆の傾斜でスパイラル羽根１２を取り付ければ、杭体２内への土砂の侵入を防止することができる。この場合、杭本体２内に取り込む土砂の量が多いほどトルクは小さくなる。また、杭本体２内に取り込む土砂の量が少ないほど杭本体２の周囲の密度が高くなり、大きな周面摩擦力を発揮する。
【００３８】
本実施の形態によれば、ねじ込み杭１の地盤への貫入にあたって、オーガーヘッド１１により翼６に先行して地盤を掘削軟化するために、ねじ込み杭１の回転に必要なトルクは、オーガー１０を使用しない場合に比べて大幅に減少する。また、ねじ込み杭１とオーガー１０の回転方向が逆であるため、施工機械に作用するモータ１５からの反力も、両者のトルクの差による反力になるため、大幅に減少する。また、翼６には杭体３の内径とほぼ等しい径の開口部７が設けられているので、オーガー１０の挿入及び回収が容易である。なお、オーガー１０は最初からねじ込み杭１内に挿入して施工してもよく、例えば支持層の近傍に達したときなどある程度ねじ込み杭１を貫入してから挿入するようにしてもよい。
【００３９】
［実施の形態６］
図７は本発明の実施の形態６に係るねじ込み杭の施工方法の説明図である。なお、実施の形態５と同じ部分にはこれと同じ符号を付し、説明を省略する。
本実施の形態においては、オーガー１０の中心部の軸方向に、後述のセメントミルクや地盤固化用薬液などの硬化性流動物を先端部に圧送するための貫通穴１３が設けられており、また、オーガーヘッド１１にはこの硬化性流動物を噴出する噴出口１４が設けられている。
【００４０】
１８は地上に設置された施工機械、１５はこの施工機械に設けた前述のモータである。
２０は例えばセメントミルクや地盤固化用薬液などの硬化性流動物のプラント（以下、硬化材プラントという）で、オーガー１０に設けた貫通穴１３とはホース２１によりオーガー１０が回転自在に連結されている。
【００４１】
本実施の形態において、ねじ込み杭１の地盤への貫入は実施の形態５の場合と同様に行われる。ねじ込み杭１が適当な深さまで貫入されたときは、硬化材プラント２０を駆動し、ホース２１を介してオーガー１０の貫通穴１３に硬化性流動物を圧送してオーガーヘッド１１に設けた噴出口１４から噴出させ、オーガーヘッド１１及び翼６の回転によって掘削軟化された土砂と攪拌させ、混合させる。このとき、ねじ込み杭１とオーガー１０の回転方向が反対のため、硬化性流動物と土砂はよく攪拌されて均一性の高い混合物となる。
【００４２】
杭先端部が支持層に達したときは、翼６とオーガーヘッド１０により支持層を十分攪拌して土砂と硬化性流動物とをよく混合したのち、ねじ込み杭１とオーガー１０の回転を停止する。
そして、モータ１５をねじ込み杭１から外し、ねじ込み杭１を地中に残置した状態でオーガー１０を反対方向に回転させながらモータ１５を上昇させれば、オーガー１０はねじ込み杭１から引き抜かれ、ねじ込み杭は地盤中に埋設されて施工は終了する。
【００４３】
本実施の形態によれば、オーガー１０の先端部から噴出される硬化性流動物と土砂が攪拌混合され、乱された地盤が固化されるため大きな先端支持力を発揮することができる。なお、硬化性流動物の噴出区間は、設計上必要なねじ込み杭１の周面摩擦に応じて決定されるもので、杭頭部から杭先端部までの全区間でもよいし、杭先端部の近傍だけでもよい。
【００４４】
【発明の効果】
本発明は、翼を設けた杭体を回転し、該杭体を前記翼の作用により地中に貫入するねじ込み杭において、前記杭体の先端部に、その下端部の内径が前記杭体の内径よりも大径の筒状体からなる拡径部を設け、該拡径部を、前記杭体の外径より大径で翼状に形成された継手部材を介して前記杭体の先端部に接合し、少なくとも前記拡径部の先端部又はその近傍に翼を設けたので、無排土、低騒音、低振動で施工できるばかりでなく、翼の拡径部の外周からの張り出し長が短かくなり、このため、施工に際して地盤の抵抗が小さく、ねじ込み杭を小さいトルクで地中に貫入することができ、大きな先端支持力を得ることができる。また、これにより拡径部及び翼の板厚を薄くできるのでコストを低減することができ、経済的である。さらに、上記の効果に加えて、杭の推進力及び支持力に寄与することができる。
【００４６】
上記のねじ込み杭において、翼を拡径部の内壁に接合したので、上記と同様の効果を得ることができ、さらに、この翼をねじ込み杭の貫入回転方向と逆向きに取付ければ、杭本体内への土砂の侵入を抑制し、先端開口部の閉塞効果を得ることができる。
【００４７】
また、本発明に係るねじ込み杭の施工方法は、上記のねじ込み杭内にオーガーを挿入し、オーガーと翼の作用によりねじ込み杭を地中に貫入するようにしたので、貫入のための施工機械のトルク及び施工機械に対するモータからの反力を低減することができる。
【００４８】
上記のねじ込み杭の施工方法において、掘削軟化した土砂中に硬化性流動物を噴出して土砂と攪拌混合するようにしたので、上記の効果が得られると共に、乱された地盤が固化されてさらに大きな先端支持力を発揮することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１に係るねじ込み杭の斜視図である。
【図２】図１の模式的縦断面図である。
【図３】本発明の実施の形態２に係るねじ込み杭の模式的縦断面図である。
【図４】本発明の実施の形態３に係るねじ込み杭の模式的縦断面図である。
【図５】本発明の実施の形態４に係るねじ込み杭の模式的縦断面図である。
【図６】本発明の実施の形態５に係るねじ込み杭の施工方法の説明図である。
【図７】本発明の実施の形態６に係るねじ込み杭の施工方法の説明図である。
【符号の説明】
１ねじ込み杭
２杭本体
３杭体
４，４ａ拡径部
６，６ａ翼
７中央開口部
９継手部材
９ａ翼状の継手部材
１０オーガー
１１オーガーヘッド
１３貫通穴
１４噴出口
１５モータ
１８施工機械
２０硬化材プラント[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screwed pile and a method for constructing the screwed pile, and more specifically, a screwing in which the pile is buried in the ground by giving a rotational force to a pile having a blade attached at least at the tip portion or the vicinity thereof. The present invention relates to a method for constructing piles and screwed piles.
[0002]
[Prior art]
Various types of threaded piles have been proposed in the past by attaching a winged plate to the tip and side of the pile and applying a rotational force using a construction machine installed on the ground to embed it in the ground by the wood screw action of the winged plate. In addition, it can be constructed with low vibration, low noise, and no soil removal, and after embedding, it can be used in the field of civil engineering and construction because it has a large tip support force using the area of the wing plate. Hereinafter, the prior art considered to be related to the present invention will be described.
[0003]
The method of embedding steel pipe piles described in Japanese Examined Patent Publication No. 2-62648 is that a bottom plate is fixed to the lower end of a steel pipe pile main body, a drilling blade is provided on the bottom plate, and a pile is attached to the outer peripheral surface of the lower end portion of the pile main body. While rotating a steel pipe pile projecting a spiral wing with a large wing width, which has an outer diameter almost twice as large as the main body's outer diameter, into a soft ground, and projecting it into a soft ground. , The soil at the tip of the pile body is softened by digging with the excavating blade at the lower end, the spiral wings are digged into the unexcavated soil on the side of the pile, and the pile body is rotated and propelled using the soil resistance as a reaction force, Extruded and softened soil and sand are extruded and compressed on the side of the pile, and the pile body is screwed into the ground without any soil (prior art 1).
[0004]
Moreover, the steel pipe pile described in Unexamined-Japanese-Patent No. 2000-110162 uses the taper-type steel pipe below the steel pipe pile, and increases the allowable penetration length based on the maximum diameter of a pile diameter, While lowering the burial cost including the material cost of the pile, a cone is fixed to the lower end of the tapered steel pipe, a spiral wing is attached to the side surface of the steel pipe above it, and the spiral wing converts rotational force into thrust, The supporting force is increased (Prior Art 2).
[0005]
Furthermore, the expanded steel pipe pile described in JP-A-2000-110160 performs excavation of the ground and sedimentation of the expanded steel pipe pile by a medium excavation method, and fixes the expanded portion to the rooted portion, Preventing adhesion of clayey soil and slime that penetrates inside the corner between the connecting part and the expanded part by the anti-adhesion wing that can be expanded to almost the same diameter to ensure a high tip support force (Prior Art 3).
[0006]
[Problems to be solved by the invention]
The steel pipe piles of the prior arts 1 and 2 are screwed into the ground and buried by applying torque to the pile head with a construction machine. A steel pipe pile having such a spiral wing has a large resistance when a pile body or a spiral wing overhangs, and a large torque is required during construction. Moreover, a large bending moment acts on a pile body by the ground reaction force which acts on a spiral wing at the time of service. For this reason, the pile body must have a large thickness or strength that can withstand a large torque during construction, and the pile body has a large thickness or strength at the time of service, or the plate thickness of the spiral blade is equivalent. It must be thick and uneconomical.
[0007]
The steel pipe pile of the prior art 3 can ensure a big tip support force by expanding the bottom of the tip. However, since there are no wings on the pile body, it is necessary to adopt a medium digging method for construction, not only is it cumbersome, but it must be treated to discharge excavated soil to the ground. Don't be. Moreover, only the supporting force for the diameter of the expanded steel pipe can be secured.
[0008]
This invention is made | formed in view of said problem, and aims at providing the construction method of the screwed pile and the screwed pile which solved the following subjects.
(1) Obtain a large tip support force with a small pile body diameter by expanding the pile tip and providing wings.
(2) To reduce the influence of bending by shortening the overhang length of the wing from the pile body, and to make economical design possible by reducing the plate thickness of the wing and pile body.
(3) When construction is performed using an auger, it is easy to insert and collect the auger.
[0009]
[Means for Solving the Problems]
The present invention relates to a screwed pile that rotates a pile body provided with wings and penetrates the pile body into the ground by the action of the wings, and the inner diameter of the lower end portion of the pile body is the tip of the pile body. A diameter-enlarged portion made of a cylindrical body having a diameter larger than the inner diameter is provided, and the diameter-enlarged portion is formed at the tip of the pile body via a joint member formed in a wing shape having a diameter larger than the outer diameter of the pile body. It joined, is provided with a wing tip or vicinity thereof of at least the enlarged diameter portion.
[0012]
In the above screwed pile, the wing was joined to the inner wall of the enlarged diameter portion.
[0013]
The construction method of the screwed pile according to the present invention includes inserting an auger into the screwed pile having a central opening in the wing and the joint member, causing the auger head to protrude from the tip of the pile, and working the auger and the wing. The screwed pile penetrates into the ground.
[0014]
In the above threaded pile construction method, a through hole is provided in the axial direction of the auger and a jet port is provided in the auger head, and a curable fluid is pumped from the through hole to be jetted from the jet port.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
1 is a perspective view of a screwed pile according to Embodiment 1 of the present invention, and FIG. 2 is a schematic longitudinal sectional view of FIG.
In both figures, 1 is a threaded pile, 3 is a pile body made of steel pipe, 4 is a taper-shaped enlarged portion formed by bending a steel plate and joined to the tip of the pile body 3 by welding. 3 and the enlarged diameter part 4 constitute a pile main body 2. Reference numeral 6 denotes a blade joined to the tip of the enlarged diameter portion 4 by welding.
[0016]
The enlarged diameter portion 4 has an outer diameter of the upper end portion that is substantially equal to the outer diameter of the pile body 3 and is enlarged in the shape of a truncated cone as it becomes the lower portion. The attachment portion 5 is provided, and a helical blade 6 formed by bending a donut-shaped steel plate, for example, is joined to the attachment portion 5 by welding.
[0017]
The expansion angle θ of the expanded diameter portion 4 is preferably about 5 ° to 20 ° according to the experimental results of the inventors. By configuring in this way, the plate thickness of the steel plate forming the expanded diameter portion 4 is The thickness of the steel pipe constituting the pile body 3 may be approximately equal to or slightly thicker. When the diameter expansion angle θ is large, the problem of load transmission can be dealt with by increasing the plate thickness of the diameter expansion portion 4.
Moreover, although the length of the enlarged diameter part 4 changes with the outer diameter of the pile body 3, the state of the ground, etc., according to the result of inventors' experiment, it is 0.5-5 times the outer diameter of the pile body 3. Degree is desirable.
[0018]
The outer diameter of the wing 6 varies depending on the outer diameter of the lower end portion of the pile body 3 and the enlarged diameter portion 4 or the state of the ground, but is generally preferably about 1.5 to 3.5 times the outer diameter of the pile body 3. In addition, it is desirable that the outward projecting length (width) and the inward projecting length (width) in the state of being joined to the mounting portion 5 of the enlarged diameter portion 4 are substantially equal. Thereby, the ground reaction force which acts on the wing | blade 6 is balanced at the time of use as a foundation pile, and the bending moment which acts on the enlarged diameter part 4 can be reduced. In addition, if the overhang | projection length from the enlarged diameter part 4 of the wing | blade 6 is about 20% of the outer diameter of the pile body 3, the pile body 3 can be penetrated in the ground with the propulsive force of the wing | blade 6. FIG.
[0019]
The screwed pile 1 according to the present embodiment configured as described above is attached to the motor provided in the construction machine with the pile head or the upper body of the pile main body 2, and the screwed pile is rotated by this motor. By the wood screw action of the wing 6, it penetrates into the ground with no soil, low vibration and low noise.
At this time, the earth and sand below the blade 6 are excavated and softened by the blade, passed through the gap 8 of the blade 6, moved to the outer periphery of the pile body 2, and compressed, and from the central opening 7 of the blade 6 to the pile body. 2 is also taken in. Since the earth and sand moved to the outer periphery of the pile body 2 are softened by the blades 6 during the construction, the frictional resistance is low and the screwed pile 1 can be smoothly penetrated. And ground strength recovers with progress of time, a big surrounding surface frictional force is exhibited at the time of service as a foundation pile, and a big support force can be obtained with wing 6.
[0020]
According to the present embodiment, even if a wing 6 having an outer diameter larger than the outer diameter of the pile body 2 is provided, the overhang length (width) from the outer periphery of the enlarged diameter portion 4 is short, so that the resistance of the ground during construction Therefore, the screwed pile can be penetrated into the ground with a small torque. In addition, it is only necessary to make the plate thickness of the enlarged diameter portion 4 substantially the same as or slightly thicker than the pile body 2, and the plate thickness of the wing 6 can be reduced, so that the cost can be reduced and economical. is there.
Furthermore, if the extension length (width) of the blade 6 on the inside and outside of the enlarged diameter portion 4 is made substantially equal, the bending moment acting on the enlarged diameter portion 4 can be reduced, which is combined with the reduction in torque described above. Thus, the plate thickness of the enlarged diameter portion 4 and the blade 6 can be made thinner.
[0021]
Since the opening part 7 is provided in the center part of the wing | blade 6 in the screwed pile which concerns on this Embodiment, earth and sand penetrate | invade in the pile main body 2 at the time of construction. When the wing 6 reaches a hard support layer during construction, the tip portion is inserted in a closed state, but the diameter of the pile body 3 is large (therefore, the opening 7 of the wing 6 is large), In the case of soft ground, there is a possibility that the tip blocking effect cannot be obtained. In such a case, a plate or a protrusion may be provided in the enlarged diameter portion 4 in order to promote the tip closing effect (the same applies to the following embodiments).
[0022]
In the above description, the tip portion of the enlarged diameter portion 4 is spirally cut to form the attachment portion 5, and one spiral blade 6 is joined to the attachment portion by welding. The wing 6 may be divided into a plurality of pieces and joined to the mounting portion 5. Further, instead of the spiral wing 6, a flat plate wing obtained by dividing a circular steel plate, an elliptical steel plate, a square steel plate, or a donut-shaped steel plate into a plurality of pieces can be joined, and a propulsive force to the ground can be obtained. As long as it is a wing having any shape or structure, the same applies to the following embodiments.
[0023]
Furthermore, although the case where the open-type wing | blade 6 which has the opening part 7 in the center part was used was shown, the obstruction | occlusion-type wing | blade which obstruct | occludes the front-end | tip opening part of the enlarged diameter part 4 may be used, or another member is used. The tip opening may be closed. Furthermore, you may make it adjust the penetration | invasion of the earth and sand into the pile body 2 by partially obstruct | occluding the front-end | tip opening part of the enlarged diameter part 4 with a wing | blade or another member. Thus, the magnitude | size of the front-end | tip opening part of the enlarged diameter part 4 can be set suitably. Moreover, you may provide the excavation auxiliary blade for improving penetration property to a wing | blade. Moreover, although the case where the wing | blade was provided in the front-end | tip part of the enlarged diameter part 4 was shown, the front-end | tip part and outer periphery of the enlarged diameter part 4, the front-end | tip part of an enlarged diameter part, the outer periphery of the pile body 3, or the enlarged diameter part 4 and a pile The attachment position of the wing can be selected as appropriate, such as being provided on the outer periphery of the body 3 or on one of them (the same applies to the following embodiments).
[0024]
[Embodiment 2]
FIG. 3 is a schematic longitudinal sectional view of a screwed pile according to Embodiment 2 of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
In the present embodiment, instead of the tapered enlarged diameter portion 4 of the first embodiment, the enlarged diameter portion 4a is formed by a cylindrical tubular body made of a steel pipe having a diameter larger than the outer diameter of the pile body 3. The pile body 2 is configured by being joined to the pile body 3 via the joint member 9.
[0025]
The expanded diameter portion 4a is made of a steel pipe having an outer diameter of about 1.1 to 2.5 times the outer diameter of the pile body 3, and a plate thickness that is substantially the same as or slightly thicker than the pile body 3, and its length is These are set according to the case of the first embodiment. And the front-end | tip part of the enlarged diameter part 4a is cut out helically similarly to the case of Embodiment 1, and the attaching part 5 is provided, 1.5-3.5 of the outer diameter of the pile body 3 is set in this attaching part 5. A spiral wing 6 of about double is joined by welding.
[0026]
The joint member 9 is made of a donut-shaped steel plate whose inner diameter is substantially equal to the inner diameter of the pile body 3, and whose outer diameter is substantially equal to the outer diameter of the enlarged diameter portion 4a, and the upper surface is joined to the tip of the pile body 3 by welding, The upper end portion of the enlarged diameter portion 4a is joined to the lower surface by welding. In addition, since the plate | board thickness of the joint member 9 changes with the outer diameter of the pile body 3, and the vertical load which acts, it calculates | requires by numerical calculation.
In the above description, the case where the joint member 9 is constituted by a doughnut-shaped steel plate is shown, but the outer diameter may be constituted by a disk-shaped steel plate that is substantially equal to the enlarged diameter portion 4a and has no opening at the center. Alternatively, the enlarged diameter portion 4a may be formed of a cylindrical body having an elliptical cross section and joined to the pile body 3 by a joint member made of an elliptical steel plate.
The construction method and effects of the screwed pile according to the present embodiment are substantially the same as those in the first embodiment.
[0027]
[Embodiment 3]
FIG. 4 is a schematic longitudinal sectional view of a screwed pile according to Embodiment 3 of the present invention. The same parts as those of the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.
In the present embodiment, instead of the joint member 9 made of a donut-shaped, disc-shaped or elliptical steel plate according to the second embodiment, a joint member 9a is constituted by blades.
[0028]
That is, the tip portion of the pile body 3 is cut in a spiral shape to form the attachment portion 3a, and the upper end portion of the enlarged diameter portion 4a is cut in a spiral shape to form the attachment portion 5a. And the spiral wing-like joint member 9a formed by bending a donut-shaped steel plate having an inner diameter substantially equal to the inner diameter of the pile body 3 and having an outer diameter larger than the outer diameter of the enlarged diameter portion 4a, While joining to the attachment part 3a by welding, the attachment part 5a of the enlarged diameter part 4 is joined to the lower surface by welding. The joint member 9a may be larger or smaller than the outer diameter of the blade 6, and if it is large, it mainly contributes to the supporting force, and if it is small, it mainly contributes to propulsion. The wing-shaped joint member 9a is not limited to a spiral wing, and a wing having an appropriate shape or structure can be used as in the case of the wing 6 described above.
[0029]
Although the construction method, operation, and effect of the present embodiment are substantially the same as those of the second embodiment, the joint member 9a is formed in a wing shape, so that the propulsion force of the screwed pile at the time of construction, the support during service Can contribute to power.
[0030]
[Embodiment 4]
FIG. 5 is a schematic longitudinal sectional view of a screwed pile according to Embodiment 4 of the present invention.
In the present embodiment, the spiral cut portion 5 and the blade 6 provided at the tip of the tapered diameter-expanded portion 4 are omitted from the first embodiment, and the inner wall of the diameter-expanded portion 4 is, for example, a spiral blade. 6a is joined by welding.
[0031]
The construction method and effects in the present embodiment are substantially the same as those in the first embodiment, and the blade 6a contributes as a propulsion force of the screwed pile at the time of construction and contributes as a support at the time of use.
Also in the present embodiment, a wing may be provided on the tip of the enlarged diameter portion 4 or on the outer circumference of the enlarged diameter portion 4 or the pile body 3, thereby further improving the propulsive force and supporting force to the ground. it can. In this case, if the blade 6a provided on the inner wall of the enlarged diameter portion 4 is attached in the direction opposite to the direction in which the threaded pile 1 penetrates, the intrusion of earth and sand into the pile body 2 is suppressed and the tip opening is blocked. An effect can be obtained.
This embodiment can also be implemented in the second and third embodiments.
[0032]
【Example】
As the screwed pile of the first embodiment, an outer diameter of 500 mm, a plate thickness of 12 mm, a length of 20 m, a top end portion of a pile body 3, an upper end of an outer diameter of 500 mm, and a lower end of an outer diameter of 800 mm (expansion angle θ: 10 ° ), The upper end portion of the enlarged diameter portion 4 having a plate thickness of 12 mm and a length of 1 m and having a mounting portion 5 that is spirally cut off at an angle of 15 ° at the tip portion was joined by welding. Then, a blade 6 formed in a spiral shape by welding one portion of a donut-shaped steel plate having an outer diameter of 1000 mm, an inner diameter of 500 mm, and a plate thickness of 30 mm in a radial direction to the attachment portion 5 is welded. It was manufactured by joining.
[0033]
The ground to be constructed was a relatively soft sand layer up to 20 m, and the depth was a gravel layer with an N value of 50 or more.
When such a ground was penetrated by applying a rotational force to the above-mentioned screwed pile by a construction machine, it could be constructed with the same efficiency as a normal screwed pile. No abnormalities were found.
[0034]
[Embodiment 5]
FIG. 6 is an explanatory view of a method for constructing a screwed pile according to Embodiment 5 of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
In the figure, 1 is a screwed pile provided with an open-type wing 6 in the enlarged diameter portion 4, 10 is an auger inserted into the screwed pile 1, 11 is an auger head, and 12 is a spiral blade. A motor 15 is provided on a construction machine (not shown) installed on the ground, and includes two rotating shafts (an outer shaft 16 and an inner shaft 17) that rotate in opposite directions.
[0035]
Next, the construction method of the present embodiment configured as described above will be described. First, an auger 10 that is slightly longer than the screwed pile 1 is inserted into the screwed pile 1, and the auger head 11 is protruded downward from the tip of the pile. Then, the pile head of the screwed pile 1 is connected to the outer shaft 16 of the motor 15, and the head of the auger 10 is connected to the inner shaft 17. The auger head 11 is used whose outer diameter is slightly smaller than the inner diameter of the pile body 3 or whose auger head 11 expands after protruding downward from the central opening 7 of the blade 6. Even in this case, it is desirable that the outer diameter of the auger head 11 is smaller than the outer diameter of the blade 6.
[0036]
Next, the motor 15 rotates, for example, the screwed pile 1 in the forward direction and the auger 10 in the reverse direction. As a result, the auger head 11 excavates and softens the ground near the tip prior to the screwed pile 1, and the screwed pile 1 penetrates into the ground by the wood screw action of the wing 6. At this time, the earth and sand near the tip of the screwed pile 1 moves to the outer periphery of the upper pile body 2 through the gap 8 of the wing 6, and a part of the earth and sand is spiral wings of the auger 10 from the opening 7 of the wing 6. 12 is taken into the pile body 2. When the tip of the pile reaches the support layer, the screwed pile 1 is removed from the motor 15, and the motor 15 is raised while rotating the auger 10 in the opposite direction with the screwed pile 1 left in the ground. The auger 10 is pulled out from the screwed pile 1, and the screwed pile is buried in the ground, and the construction is completed.
[0037]
The amount of earth and sand taken into the pile main body 2 by the auger 10 varies depending on the size of the opening 7 at the center of the wing 6 and the dimensions and shape of the auger head 11. Try not to overflow. In addition, if the spiral blades 12 are attached with an inclination opposite to the rotation direction of the auger 10, the intrusion of earth and sand into the pile body 2 can be prevented. In this case, the torque decreases as the amount of earth and sand taken into the pile body 2 increases. Moreover, the density of the circumference | surroundings of the pile main body 2 becomes high, so that the quantity of the earth and sand taken in in the pile main body 2 is small, and a large circumferential friction force is exhibited.
[0038]
According to the present embodiment, when the screwed pile 1 penetrates into the ground, the auger head 11 causes the auger 10 to rotate the screwed pile 1 in order to soften the ground by excavating and softening the ground prior to the blade 6. Compared to when not in use, it is greatly reduced. In addition, since the rotation directions of the screwed pile 1 and the auger 10 are opposite, the reaction force from the motor 15 acting on the construction machine is also a reaction force due to the difference between the torques of the two, so that it is greatly reduced. Further, since the wing 6 is provided with the opening 7 having a diameter substantially equal to the inner diameter of the pile body 3, the auger 10 can be easily inserted and recovered. The auger 10 may be inserted into the screwed pile 1 from the beginning, and may be inserted after the screwed pile 1 has penetrated to some extent, for example, when reaching the vicinity of the support layer.
[0039]
[Embodiment 6]
FIG. 7 is an explanatory view of a method for constructing a screwed pile according to Embodiment 6 of the present invention. The same parts as those in the fifth embodiment are denoted by the same reference numerals, and description thereof is omitted.
In the present embodiment, a through-hole 13 is provided in the axial direction of the central portion of the auger 10 to pump a curable fluid such as cement milk or a chemical solution for solidification to the tip, which will be described later. The auger head 11 is provided with a spout 14 for ejecting the curable fluid.
[0040]
18 is a construction machine installed on the ground, and 15 is the above-described motor provided on this construction machine.
Reference numeral 20 denotes a curable fluid plant (hereinafter referred to as a “hardening material plant”) such as cement milk and ground solidifying chemical solution. The auger 10 is rotatably connected to a through hole 13 provided in the auger 10 by a hose 21. Yes.
[0041]
In the present embodiment, penetration of the screwed pile 1 into the ground is performed in the same manner as in the fifth embodiment. When the screwed pile 1 is penetrated to an appropriate depth, the hardener plant 20 is driven, and the curable fluid is pumped through the hose 21 to the through hole 13 of the auger 10 to provide a jet port provided in the auger head 11. 14 and agitated and mixed with the earth and sand softened by the rotation of the auger head 11 and the blade 6. At this time, since the rotation directions of the screwed pile 1 and the auger 10 are opposite, the curable fluid and the earth and sand are well agitated to form a highly uniform mixture.
[0042]
When the pile tip reaches the support layer, the support layer is sufficiently agitated by the blade 6 and the auger head 10 to thoroughly mix the earth and curable fluid, and then the rotation of the screwed pile 1 and the auger 10 is stopped. .
And if the motor 15 is lifted while removing the motor 15 from the screwed pile 1 and rotating the auger 10 in the opposite direction with the screwed pile 1 left in the ground, the auger 10 is pulled out from the screwed pile 1 and screwed. The pile is buried in the ground and the construction is completed.
[0043]
According to the present embodiment, the curable fluid ejected from the tip of the auger 10 and the earth and sand are agitated and mixed, and the disturbed ground is solidified, so that a large tip support force can be exhibited. In addition, the ejection section of the curable fluid is determined according to the peripheral surface friction of the screwed pile 1 necessary for the design, and may be the entire section from the pile head to the pile tip, or the pile tip Only the neighborhood may be used.
[0044]
【The invention's effect】
The present invention relates to a screwed pile that rotates a pile body provided with wings and penetrates the pile body into the ground by the action of the wings, and the inner diameter of the lower end portion of the pile body is the tip of the pile body. A diameter-enlarged portion made of a cylindrical body having a diameter larger than the inner diameter is provided, and the diameter-enlarged portion is formed at the tip of the pile body via a joint member formed in a wing shape having a diameter larger than the outer diameter of the pile body. joined, is provided with the blade at the tip or near the at least the enlarged diameter portion, no soil discharge, low noise, not only can construction with low vibration, overhang length from the outer periphery of the enlarged diameter portion of the blade is short Thus, the ground resistance is small during construction, the screwed pile can be penetrated into the ground with a small torque, and a large tip support force can be obtained. In addition, this makes it possible to reduce the thickness of the enlarged diameter portion and the blade, thereby reducing the cost and being economical. Furthermore, in addition to the above effects, it can contribute to the propulsive force and support force of the pile.
[0046]
In the above screwed pile, since the blade is joined to the inner wall of the enlarged diameter portion, the same effect as described above can be obtained, and if the blade is mounted in the direction opposite to the penetration rotation direction of the screwed pile, the pile body The intrusion of earth and sand into the inside can be suppressed, and the blocking effect of the tip opening can be obtained.
[0047]
Further, the construction method of the screwed pile according to the present invention is such that the auger is inserted into the screwed pile and the screwed pile is penetrated into the ground by the action of the auger and the wing. Torque and reaction force from the motor against the construction machine can be reduced.
[0048]
In the construction method of the above screwed pile, since the curable fluid was ejected into the excavated and softened earth and sand and mixed with the earth and sand, the above effect was obtained, and the disturbed ground was further solidified. A large tip support force can be exhibited.
[Brief description of the drawings]
FIG. 1 is a perspective view of a screwed pile according to a first embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of FIG.
FIG. 3 is a schematic longitudinal sectional view of a screwed pile according to a second embodiment of the present invention.
FIG. 4 is a schematic longitudinal sectional view of a screwed pile according to a third embodiment of the present invention.
FIG. 5 is a schematic longitudinal sectional view of a screwed pile according to a fourth embodiment of the present invention.
FIG. 6 is an explanatory diagram of a threaded pile construction method according to Embodiment 5 of the present invention.
FIG. 7 is an explanatory diagram of a threaded pile construction method according to Embodiment 6 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Screwed-in pile 2 Pile main body 3 Pile body 4, 4a Expanded-diameter part 6, 6a Wing 7 Central opening 9 Joint member 9a Wing-like joint member 10 Auger 11 Auger head 13 Through-hole 14 Spout 15 Motor 18 Construction machine 20 Hardening material plant

Claims

翼を設けた杭体を回転し、該杭体を前記翼の作用により地中に貫入するねじ込み杭において、
前記杭体の先端部に、その下端部の内径が前記杭体の内径よりも大径の筒状体からなる拡径部を設け、該拡径部を、前記杭体の外径より大径で翼状に形成された継手部材を介して前記杭体の先端部に接合し、少なくとも前記拡径部の先端部又はその近傍に翼を設けたことを特徴とするねじ込み杭。In a screwed pile that rotates a pile body provided with wings and penetrates the pile body into the ground by the action of the wings,
Provided at the leading end of the pile body is an enlarged portion made of a cylindrical body having an inner diameter at the lower end that is larger than the inner diameter of the pile body, and the enlarged diameter portion is larger in diameter than the outer diameter of the pile body. in via a joint member formed on the wing and joined to a front end portion of the pile body, screwed pile, characterized in that a wing tip or vicinity thereof of at least the enlarged diameter portion.

前記翼を拡径部の内壁に接合したことを特徴とする請求項１に記載のねじ込み杭。The screwed pile according to claim 1, wherein the blade is joined to an inner wall of the enlarged diameter portion.

翼及び継手部材に中央開口部を有する請求項１又は２のねじ込み杭内にオーガーを挿入してそのオーガーヘッドを杭先端部から突出させ、該オーガーと前記翼の作用によりねじ込み杭を地中に貫入することを特徴とするねじ込み杭の施工方法。The auger is inserted into the screwed pile of claim 1 or 2 having a central opening in the wing and the joint member, and the auger head is protruded from the tip of the pile, and the screwed pile is brought into the ground by the action of the auger and the wing. A threaded pile construction method characterized by penetration.

オーガーの軸方向に貫通穴を設けると共にオーガーヘッドに噴出口を設け、前記貫通穴から硬化性流動物を圧送して前記噴出口から噴出させることを特徴とする請求項３記載のねじ込み杭の施工方法。The construction of the screwed pile according to claim 3 , wherein a through hole is provided in the axial direction of the auger, a jet port is provided in the auger head, and a curable fluid is pumped from the through hole and jetted from the jet port. Method.