JP3758161B2

JP3758161B2 - Steel pipe foundation pile

Info

Publication number: JP3758161B2
Application number: JP2002367830A
Authority: JP
Inventors: 文男星
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-12-19
Filing date: 2002-12-19
Publication date: 2006-03-22
Anticipated expiration: 2022-12-19
Also published as: JP2003119777A

Description

【０００１】
【発明の属する技術分野】
本発明は、中低層のアパート、マンション等の建物や倉庫の基礎杭であり、より詳しくは、杭先端に切削刃（切削羽根）及び支持羽根（掘進羽根）を備え、下方に押圧しながら杭を回転させて無振動、無騒音、無排土で杭打ちし、所望支持層への杭打ち施工可能なものであり、建築物の基礎工事の技術分野に属するものである。
【０００２】
【従来の技術】
【特許文献１】
特公平２−６２６４８号公報
【特許文献２】
実公昭４−３９２９３号公報
〔従来例１（図５）〕
鋼管杭の先端に掘削刃及び螺旋翼を備えたものは特公平２−６２６４８号公報で提案されている。
即ち、図５に示す如く、鋼管製の杭本体の先端を底板で閉止し、底板には下方に向けて掘削刃の２片を突設し、杭本体の下端部には外周面に沿って翼幅の大きい螺旋翼をほぼ１巻きに亘り突設している。
【０００３】
そして、軟弱地盤にねじ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喰い込ませ、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圧縮し、無排土で地中に杭体をねじ込んで行くものである。
【０００４】
〔従来例２（図６）〕
また、ねじ込み杭の先端を円錐部として円錐部周面に多数の刃を付設したものも実公平４−３９２９３号公報により提案されている。
即ち、図６に示す如く、杭部材には内部をコンクリート充填すると共に下端に雌ネジ部材を、上端に雄ネジ部材を配置して接続長尺化可能とし、円錐状で杭部材の外径より大きめの先端シューの内部にもコンクリート充填すると共に、上端中央に雄ネジ部材を突設し、シュー外周面には多数の刃を螺旋状に分散形態で取付け、該シューを杭部材の先端に螺合固定してねじ込み杭とするものである。
【０００５】
そして、杭部材の上端に回転を与えながら杭部材を地中にねじ込み、新たな杭部材をネジ接合してねじ込むことにより、杭部材間の接合部で接合強度が増し、更に、杭部材より大径の先端シューにより杭部材の地中への貫入を容易とするものである。
【０００６】
【発明が解決しようとする課題】
従来例１（図５）のものは、無振動、無騒音、無排土で杭打ち出来るものではあるが、杭本体の外径のほぼ２〜３倍の外径を有する螺旋翼を内周端縁の鋼管外周に巻き付け溶接するのは煩雑、且つ熟練を要する困難な作業であり、底板の鋼管端への溶接取付け、及び掘削刃の底板への溶接取付けも煩雑な作業である。
【０００７】
そして、先端が底板であって底板外周部に掘削刃が存在するため、地盤の浅い所に硬い地層のある場合や、支持地盤までに特に硬い地層は無くても途中の杭先端位置に転石や岩塊等の障害物がある場合には、杭先端の底板が障害物を貫通することは出来なく、所定地盤深度まで杭を打込むことが出来ない。
しかも、螺旋翼が連続１ピッチ長であるため、掘進突入作用点（螺旋翼下端）が外周の１点のみとなること、及び先端が底板であることにより、杭１は掘進時に芯ずれを生じ易く、平滑な掘進作用が期待出来ない。
【０００８】
また、従来例２のものにあっても、杭部材外周への拡径翼の溶接取付けや先端シューの外殻表面への刃の溶接取付けは、従来例１のものと同様、煩雑、且つ熟練を要する困難な作業であり、例え型鋳造しようとしても、先端シューの外形及び多数の刃の配置形態から型枠組みが非常に煩雑、且つ困難であるため、分割鋳造品の溶接一体化となって均質強度を有する先端シューの製造が困難であると共に、製作コストも高くなる。
【０００９】
そして、先端シューの外径は杭本体の杭部材外径より大であるため、杭打込時には、杭本体外周面の土質は先端シューによって切削されて杭部材の貫入は容易とはなるが、杭部材外周部の土質を切削するため、摩擦杭としての杭部材外周面の摩擦支持力は低下する。
しかも、先端シューが円錐形態であるため、掘進作業中の地盤の硬度（Ｎ値）の変化の検出把握が困難である。
【００１０】
本発明は、これら摩擦杭の問題点を、解決又は改善するものであり、低コストで製作出来、且つ、転石や岩塊の存在する土質でも所定位置に杭打ち出来る切削力を発揮し、所望Ｎ値への到達が容易に把握出来、且つ、強大な杭支持力を発揮する新規な頭部を備えた鋼管基礎杭を提供するものである。
【００１１】
【課題を解決するための手段、及び作用】
本発明鋼管杭Ｐは、例えば図１に示す如く、鋼管１の先端に、円筒部２０及び先端面Ｔｓを有する裁頭円錐ヘッド２１から成る頭部２を嵌合固着した杭Ｐであって、頭部２は、円筒部２０の基端２Ｂに鋼管１内への嵌入用の突出胴２２を備え、基端２Ｂの突出胴周面には適宜間隔で当接片２５を備え、円筒部２０には各掘進羽根２３，２３´を、円錐ヘッド２１には各切削羽根２４，２４´を、各掘進羽根相互、及び各切削羽根相互が外周面上に略半周の傾斜形態で、且つ、１８０°回転対称に、配置したものである。
【００１２】
尚、「１８０°回転対称」とは、図１の軸線Ｘ−Ｘに対して１８０°回転させれば同一形態が表出することを意味し、例えば図１に於いて、頭部２上の掘進羽根２３及び切削羽根２４が左側下降形態で表出し、掘進羽根２３´及び切削羽根２４´が裏側で右側下降形態となっているが、頭部を軸線Ｘ−Ｘの周りに１８０°回転させれば、裏側の掘進羽根２３´及び切削羽根２４´が表出し、且つ図１の掘進羽根２３及び切削羽根２４の位置を占めることを意味する。
【００１３】
また、掘進羽根２３，２３´の傾斜角及び切削羽根２４，２４´の傾斜角は、必要に応じて決定するものであり、杭Ｐの回転押込み、即ち頭部２の回転押込み時に円筒部２０上の掘進羽根２３，２３´が杭Ｐの掘進案内を、円錐ヘッド２１上の切削羽根２４，２４´が杭先端の地山を切削すれば良い。
また、先端面Ｔｓは、杭の貫入時の圧力変化の検出を容易にするものであって、貫入抵抗の増加を最小限に抑制する必要上、５〜１０cm径の小面積の平面であるのが好ましい。
【００１４】
従って、頭部２を鋼管１先端に嵌着固定するため、頭部２を別体として型鋳造して鋼管に溶接すれば良く、複雑な形態の頭部２を備えた杭Ｐが合理的に製作出来る。
また、頭部２の外周面に配置した各掘進羽根２３，２３´、及び切削羽根２４，２４´が１８０°対称の略半周羽根であるため、頭部２は２分割型を用いて容易に鋳造出来る。
【００１５】
更に、頭部２が先端に先端面Ｔｓを備えているため、掘進作業中には先端面Ｔｓが貫入抵抗力の受圧面として作用することにより、土質の抵抗力変化の感知が容易となり、掘進作業中にＮ値の増大域をオーガーのトルク負荷の増加として鋭敏に感知出来、所定Ｎ値の支持層までの各杭毎の打込みが容易となり、各杭が均斉な支持力を備えた基礎杭打込み施工が可能となる。
【００１６】
また、各羽根２３，２３´及び２４，２４´は、略半周で１８０°対称配置、即ち、分割対称配置であるため、頭部上での羽根２３，２４の配置域長Ｚ２３，Ｚ２４は、連続螺旋形態での羽根長さ配置域の１／２長さ内に収めることが出来、即ち、螺旋半周内に螺旋１周分の羽根を収めることが出来、限られた長さの頭部２上での各羽根の傾斜角の設定の自由度があり、掘進羽根２３，２３´間は土詰りの生じない配置と出来、切削羽根２４，２４´間は、切削力向上の傾斜角と出来る。
【００１７】
しかも、各掘進羽根２３，２３´、及び各切削羽根２４，２４´相互が１８０°対称であるため、杭Ｐの回転押込み時には、掘進作用応力、及び切削作用応力が１８０°対称で協同作用し、地山の同一水準位置で２個所同一の切削及び掘進作用が生じるため、杭Ｐの切削及び掘進作用が平滑となる。
【００１８】
また、本発明杭Ｐにあっては、頭部２の円筒部２０が基端に鋼管内への嵌入用の突出胴２２を備え、基端２Ｂの突出胴周面には適宜間隔で当接片２５を備えるのが必須であるが、当接片２５は、図１に示す如く、鋼管１の先端１Ｔの頭部２基端２Ｂへの当接ストッパーとして作用するものであり、各当接片２５が同形態で鋼管先端と当接するために、各当接片２５は、少なくとも基端２Ｂからの突出寸法ａは等しくするのが好ましい。
【００１９】
従って、頭部２の鋼管先端への嵌合は、突出胴２２の嵌入によって容易であり、当接片２５で形成される幅ａ（当接片突出寸法）の突出胴２２上の間隔Ｓを溶接用肉盛り代として、当接片２５を含む間隔Ｓを杭径Ｄ１と面一に肉盛り溶接することにより、頭部２と鋼管１との均斉、且つ強固な溶接が可能となり、本発明鋼管杭Ｐの製作が容易となる。
【００２０】
第２の発明の鋼管杭２は、例えば図１に示す如く、鋼管１の先端に、円筒部２０及び先端面Ｔｓを有する裁頭円錐ヘッド２から成る頭部２を嵌合固着した杭Ｐであって、円筒部２０には、各掘進羽根２３，２３´が緩傾斜角θ２３の略１／２周のスパイラル配置であり、円錐ヘッド２１上には、各切削羽根２４，２４´が急傾斜角θ２４の略１／２周スパイラル配置で、各掘進羽根２３，２３´相互、及び各切削羽根２４，２４´相互が、外周面上に１８０°回転対称に配置したものである。
この場合、緩傾斜角θ２３の掘進羽根２３，２３´が地山を切り崩すことなく回転して杭Ｐに推力を発生させても、急傾斜角θ２４の切削羽根２４，２４´の回転は杭先端部の地山に対して切削分力を発生させて地山の切削作用を奏する。
【００２１】
従って、円錐ヘッド２１の小面積の先端面Ｔｓを備えた円錐周面の地山への突入作用と相俟って、円錐ヘッド２１部での地山の切削、切り崩し作用と、円筒部２０での推力発生作用とによって、鋼管杭Ｐは杭Ｐ外周面の地山を切削軟化させることなく、転石や岩塊の存在する地層にも所定どおりの平滑杭打ちが可能となり、打込んだ鋼管杭Ｐは、掘進羽根２３，２３´が緩傾斜であるための大きな支持力と、鋼管杭Ｐの外周面での摩擦支持力とによって必要、且つ十分な支持力を発揮する。
【００２２】
また、当接片２５外面を円筒部２０の外周と面一形態とし、頭部２基端の突出胴２２を鋼管１内に嵌入して、当接片２５によって形成された頭部基端２Ｂと鋼管先端１Ｔとの間隔Ｓを溶接肉盛りするのが頭部２と鋼管１との嵌合固着上好都合である。
この場合、当接片２５の型枠形成が容易であるとともに、溶接時の間隔Ｓ内への面一の肉盛り溶接作業が容易となり、強固な溶接一体化が可能である。
【００２３】
また、本発明鋼管杭Ｐにあっては、円筒部２０の外径Ｄ２０が鋼管１の外径Ｄ１と同径であり、掘進羽根２３，２３´の外径Ｄ２３が鋼管外径Ｄ１の略１．５〜２倍径であり、且つ、切削羽根２４，２４´の外径Ｄ２４が鋼管外径Ｄ１と同等かそれ以下であるのが好ましい。
この場合、円筒部２０の外径Ｄ２０が鋼管外径Ｄ１と同径であることにより杭Ｐの貫入が平滑となり、掘進羽根２３，２３´は、杭打ち後は支持羽根として機能するので、外径Ｄ２３が鋼管外径Ｄ１の１．５倍以上あれば支持力が発揮出来、外径Ｄ２３が鋼管外径Ｄ１の２倍以上であれば掘進回転負荷が強大となって作業性に問題が生じるため、Ｄ２３＝１．５〜２Ｄ１が作業性及び杭支持性面から好ましい。
【００２４】
そして、切削羽根２４，２４´は、杭先端の地山を切削軟化させるため、鋼管１の外周部を切削軟化させると杭Ｐの側周面での摩擦支持力が極端に減少するので、切削羽根２４，２４´の作用範囲を杭外径Ｄ１内に留めるのが好ましい。
従って、円筒部外径Ｄ２０、鋼管外径Ｄ１、掘進羽根外径Ｄ２３、切削羽根外径Ｄ２４を上記条件に設定すれば、合理的な杭回転応力の下に、必要、且つ十分な支持力を有する基礎杭Ｐの平滑な打込み施工が出来る。
【００２５】
また、各切削羽根２４，２４´の羽根幅Ｗ２４が基端２４Ｂから先端２４Ｔへと漸増しているのが好ましい。
切削羽根２４，２４´を配置する円錐ヘッド２１は、その先端面Ｔｓを備えた円錐周面と円錐周面の切削羽根２４，２４´とによって、浅い所の硬い地層、転石や岩塊の存在する地層を貫通させるためであり、円錐ヘッド２１の長さＬ２１は、強度面から円錐ヘッド径、即ち円筒部径Ｄ２０と略同等長さに抑えるのが好ましい。
【００２６】
この場合、切削羽根２４，２４´の幅Ｗ２４を基端２４Ｂから先端２４Ｔへ漸増する形態とすれば、比較的に短い円錐ヘッド長Ｌ２１の円錐表面に比較的急傾斜角θ２４で一対の長い切削羽根２４，２４´を１８０°対称に配置出来、切削羽根径Ｄ２４が鋼管杭径（鋼管径）Ｄ１を超えない寸法内で長い切削羽根２４，２４´の取付けが可能となる。
【００２７】
従って、円錐ヘッド２１は、鋼管杭Ｐの外周面の対地層摩擦力を減じることなく、即ち、鋼管杭Ｐの外周面の地層を切削することなく、鋼管径Ｄ１の範囲内での杭先端の地山に強力な切削作用を奏することが可能となり、鋼管杭Ｐは、所定の杭打ち場所での地層の硬軟に関係なく杭打ち可能で、且つ頭部２の掘進羽根２３，２３´、鋼管１上の掘進羽根２６，２６´；２７，２７´、及び杭本体（鋼管１）の外周面の摩擦力とで十分な支持力を発揮する鋼管杭となる。
【００２８】
また、図４に示す如く、円筒部２０と接続した鋼管１に、少なくとも一対の掘進羽根２６，２６´；２７，２７´を、各掘進羽根相互が外周面上に略半周の傾斜形態で、且つ、１８０°回転対称に配置するのが特に好ましい。
この場合、掘進羽根対の配置間隔、羽根径は適用現場に応じて適宜に選択決定すれば良いが、掘進羽根は杭打込み後は杭支持体として機能するので、図４の如く、複数対配置する場合は、頭部の掘進羽根２３を含む各掘進羽根の間隔Ｌ１，Ｌ２は等間隔で且つ５０cm〜８０cm配置が好ましい。
【００２９】
そして、鋼管表面への掘進羽根の付設は溶接手段によって可能であり、各掘進羽根対は、２枚の略半周の羽根片であるため、１周スパイラルの羽根の溶接固定より遥かに容易であり、基礎杭打込み現場での地質に応じた掘進羽根配置が可能となり、地質に応じた十分の支持力を備えた杭の合理的な打込み施工が可能となる。
【００３０】
また、図４に示す如く、鋼管１上の掘進羽根径Ｄ２６，Ｄ２７が円筒部２０上の掘進羽根径Ｄ２３より大であるのが好ましい。
一般に、地盤は建物の大きさに応じた必要支持力（Ｎ値）を備えた所定支持層までの中間にも杭に打込み抵抗を生じさせる部分が存在することがあり、杭の頭部の掘進羽根は損傷を受ける危険があるため、頭部の掘進羽根は径Ｄ２３を小さくして杭支持力の減少を鋼管上の大径の掘進羽根で補償するのが有利である。
【００３１】
従って、杭の掘進羽根対は、部分的硬質土をヘッドの切削羽根２４と共に先行切削掘進する頭部の掘進羽根２３，２３´が小径であるため掘進損傷を抑制出来、後行の鋼管上の切削掘進の抵抗の少ない掘進羽根２６，２６´，２７，２７´を大径として十分な杭支持力を得るのが合理的である。
この場合、図４の如く、掘進羽根径Ｄ２３，Ｄ２６，Ｄ２７は、上方へ行くにしたがって順次大径（Ｄ２３＜Ｄ２６＜Ｄ２７）とするのが、掘進羽根の掘進作用面及び支持機能面から好ましく、鋼管１上の掘進羽根径Ｄ２６，Ｄ２７は、鋼管径Ｄ１の３〜５倍に設定すれば、軟質地層にも対処出来、必要に応じて鋼管１上の掘進羽根を３段、又は４段に設けても良い。
【００３２】
〔実施例（図１、図２）〕
鋼管１は鋼管杭としての市販の外径Ｄ１が１６５．２mm、肉厚５．５mmのものを採用する。
頭部２は、一般肉厚１０mmの鋳造品であり、円筒部２０の外径Ｄ２０を鋼管１の外径Ｄ１と同一とし、円筒部長さＬ２０を１００mm、円錐ヘッド２１の長さＬ２１を１５５mmとし、先端には６cm径の平坦な先端面Ｔｓを備えた形態とする。
【００３３】
そして、円筒部２０の外周には、２枚の掘進羽根２３，２３´を、傾斜角θ２３が１５°で掘進羽根外径Ｄ２３が２５０mmに、肉厚７mmで各羽根２３，２３´が半周に亘って軸心Ｘ−Ｘに１８０°対称、即ち、軸心Ｘ−Ｘで１８０°回転させれば回転前と回転後とは掘進羽根２３，２３´が同一形態で現出する１８０°表裏対称に配置する。
【００３４】
また、円錐ヘッド２１の外周面にも、図１の如く、肉厚５．５mmの各半周に亘る切削羽根２４，２４´を傾斜各θ２４が４５°で軸心Ｘ−Ｘに１８０°回転対称に、且つ、切削羽根の突出寸法（幅Ｗ２４）は羽根基端２４Ｂが円錐ヘッド２１の基端２１Ｅで収斂して０であり、先端部へと漸増して最先端２４Ｔでの円錐周面からの突出幅Ｗ２は２５mmとする。
【００３５】
また、図２に示す如く、頭部２の基端２Ｂからは、突出胴２２を突出長Ｌ２２が２０mm、径Ｄ２が鋼管１の内部に嵌入密接出来る寸法（１５４mm）に、且つ、突出胴２２の基端上には９０°間隔で４個の当接片２５を配置する。
尚、各当接片２５は、高さが円筒部２０外周と面一であり、且つ突出長ａを３mmとする。
【００３６】
上記Ｘ−Ｘ線１８０°対称の形状の頭部２を２分割型締めで一体鋳造し、所定長さを有する鋼管１の先端１Ｔに突出胴２２を密接嵌入し、頭部基端２Ｂと鋼管先端１Ｔとの間に当接片２５群によって形成される間隔Ｓに肉盛り溶接し、間隔Ｓを当接片２５と共に溶接によって略面一に仕上げる。
また、鋼管１外周には頭部２の円筒部２０上の掘進羽根２３，２３´の位置から５０cmの間隔Ｌ１を保って２段目の掘進羽根２６，２６´を、該２段目の掘進羽根から５０cmの間隔Ｌ２を保って３段目の掘進羽根２７，２７´を溶接固定する。
２段目掘進羽根径Ｄ２６は４０cm、３段目掘進羽根径Ｄ２７は４５cmであるが、各掘進羽根の傾斜角θ２３，θ２６，θ２７及び羽根肉厚は同一とする。
【００３７】
〔実施例効果〕
本発明杭Ｐの頭部２は、緩傾斜（１５°）の半周長の掘進羽根２３，２３´を表裏交差形態で外周面に備えた円筒部２０と、急傾斜（４５°）の半周長の切削羽根２４，２４´を表裏交差形態で外周面に備えた円錐ヘッド、及び円筒部基端２Ｂから当接片２５を備えた突出胴２２を突出した外形が１８０°回転対称の複雑な形態ではあるが、１８０°回転対称であるため、２分割型枠による型枠組みも脱型も容易となり、鋳造製作が容易である。
また、頭部２の鋼管先端１Ｔへの取付けも、突出胴２２の挿入嵌合と、当接片２５による間隔Ｓの形成によって、間隔Ｓを溶接代とした強固な溶接固着が簡単に実施出来る。
【００３８】
また、頭部２の掘進羽根２３，２３´、鋼管１上の掘進羽根２６，２６´；２７，２７´全てが同一角度の緩傾斜であり、切削羽根２４，２４´が急傾斜であるため、鋼管杭Ｐの掘進時には、掘進羽根で地山を切り崩さないように回転推進させても、切削羽根２４，２４´は切削掻き取り作用を奏して杭先端の地山を杭Ｐの径Ｄ１の範囲内で切り崩すだけであり、鋼管杭Ｐの外周面の地山の未切削状態（未崩壊状態）で鋼管杭Ｐの各掘進羽根２３，２３´；２６，２６´；２７，２７´による推進打込みが平滑に実施出来る。
【００３９】
そして、進行方向１段目の大きな掘進抵抗を受ける掘進羽根２３，２３´は小径（鋼管径Ｄ１の約１．５倍）であるため、破損が抑制出来、掘進抵抗の比較的小さな２段目の掘進羽根２６，２６´、及び３段目の掘進羽根２７，２７´は大径（鋼管径Ｄ１の３〜５倍）であり、且つ各掘進羽根面が緩傾斜（１５°）であることにより十分な杭支持力を発揮し、鋼管１の外周面での未切削の地山による摩擦力と、所望Ｎ値を有する支持層による先端面Ｔｓを有する円錐ヘッド２１の支持力とが相俟って、鋼管杭Ｐは、建物基礎杭としての必要、且つ十分な支持力を発揮する。
【００４０】
しかも、２枚の掘進羽根２３，２３´及び２枚の切削羽根２４，２４´は１８０°回転対称の配置であるため、それぞれスパイラル半周ピッチの領域Ｚ２３，Ｚ２４内に半周ピッチ長の羽根を２枚配置出来、地山に対する同一水準での同一の切削作用及び掘進作用が半周ピッチの狭い領域内で常に１８０°対称に表裏両側で作用することとなり、強力で均斉、且つスムーズな切削及び掘進作用を奏する。
【００４１】
そして、杭Ｐ先端の切削羽根２４，２４´が円錐ヘッド上に存在するため、杭Ｐの回転推進は芯ずれの生じ難い進行となり、切削羽根２４，２４´による表裏１８０°対称の切削と相俟って硬い地層の切り崩しも可能となり、杭Ｐの切削掘進が強力、且つ、スムーズに遂行出来る。
しかも、円錐ヘッド２１の先端面Ｔｓの存在によって、杭Ｐの先端での打込み抵抗が若干増大して、杭打込み抵抗力の変化の感知が容易となるため、掘進作業中での地盤の硬さ変化、即ち、地盤の支持力変化（Ｎ値変化）を回転トルク変化として鋭敏に把握出来、機械オペレータは、各杭Ｐの所定支持層への到達による打込み停止が正確に実施出来、各杭Ｐ毎の施工管理が容易となる。
【００４２】
〔変形例（図３）〕
図３の変形例は、実施例（図１）のものに於いて、掘進羽根２３，２３´の一対を上下２段に配置したものである。
即ち、頭部２の円筒部２０のみを図１のものより長くし、周面のスパイラル１ピッチ内にスパイラル２ピッチ分の羽根を配置したものである。
従って、実施例のものに比べて、頭部２の単価、即ち杭Ｐの単価は高くなるが、杭Ｐの推進力及び掘進羽根による杭支持力は向上する。
【００４３】
〔その他〕
実施例（図１）及び変形例（図３）では、切削羽根２４，２４´を４５°の急傾斜として、羽根幅も基端２４Ｂから先端２４Ｔへと漸増タイプとし、掘進羽根２３，２３´を緩傾斜（１５°）としたが、切削羽根を基端から先端まで等幅として掘進羽根と近似の傾斜角で配置することも可能である。
この場合は、切削羽根の配置領域Ｚ２４は、実施例より短くなり円錐ヘッド２１の周面中間部に短寸化した羽根片２４，２４´を配置することとなるが、杭Ｐは円錐ヘッド先端面Ｔｓを中心に回転推進するため、ヘッド先端面Ｔｓと円錐ヘッド２１の傾斜周面と、切削羽根２４，２４´先端との協同作用により杭先端での地山の切削は可能である。
【００４４】
また、各切削羽根２４，２４´の先端幅Ｗ２４及び掘進羽根２３，２３´の先端幅Ｗ２３全幅に亘り肉厚にテーパーを付与すれば、地山への喰い込みがよりスムーズとなる。
また、掘進羽根２３，２３´（１段目掘進羽根）の外径Ｄ２３は、実施例では鋼管１の外径Ｄ１の１．５倍としたが、羽根幅Ｗ２３での杭支持力を高めるために、本発明の範囲内で掘進羽根２３，２３´の外径Ｄ２３は必要に応じて大きく出来、鋼管径Ｄ１の２倍又はそれ以上とすることも可能である。
また、実施例では、各掘進羽根径をＤ２３＜Ｄ２６＜Ｄ２７としたが、鋼管１上の掘進羽根２６，２６´；２７，２７´の径Ｄ２６，Ｄ２７は同径でも良い。また、円錐ヘッド２１の先端面Ｔｓは、実施例では６cm径としたが、杭の芯ずれ抑制の面からは小さい程好ましく、杭打込みに使用する機械に応じて掘進回転トルク変化の感知の可能な最少平面とすれば良い。
【００４５】
【発明の効果】
円錐ヘッド２１周面には切削羽根２４，２４´を備え、円筒部２０周面には掘進羽根２３，２３´を備えた頭部２を鋼管１の先端に嵌合固着し、鋼管１上に必要掘進羽根を固定するだけで切削、掘進用の杭が形成出来るため、複雑な形態の頭部２のみを必要機能を備えた別体品として製作しておき、鋼管１と別体で製作、備蓄出来、鋼管杭Ｐの保管、製作管理が容易となる。
【００４６】
しかも、頭部２は、略半周長の各切削羽根２４，２４´相互、各掘進羽根２３，２３´相互、を頭部外周面上に１８０°回転対称に配置するため、羽根配置は螺旋１／２ピッチ内に１周長の羽根が配置出来て、短寸の配置域Ｚ２３，Ｚ２４にコンパクトに羽根配置出来ることと、各切削羽根及び各掘進羽根が地山の同一水準位置での１８０°回転対称の２個所で作用することとが相俟って、短寸の切削域Ｚ２４及び掘進域Ｚ２３での強力、且つ平滑な切削及び掘進作用が発揮出来る。
更に、円錐ヘッド２１の頭部には貫入抵抗を受ける先端面Ｔｓが存在するため、杭Ｐの打込み時の土中への貫入抵抗力の変化がオペレータにより検出可能となり、各打込杭Ｐ毎に所定のＮ値の支持層へ到達の正確な把握が可能となって、全打込杭Ｐの均質な打込み施工が可能となる。
【００４７】
更に、切削羽根は円錐ヘッドの傾斜周面での横ぶれのない回転の下での作用となり、１８０°回転対称配置の切削羽根先端２４Ｔ及び掘進羽根先端２３Ｔの地山への喰い込み作用と相俟って、強力、且つ、スムーズな切削及び掘進が可能となる。
【００４８】
また、鋼管１に固着する頭部２は、形態が１８０°回転対称であるため、その複雑な形状も２分割型の型締めによって一体鋳造出来、型組み及び鋳造後の型割り作業も容易であり、強力な切削力及び掘進力を発揮する鋼管杭が低コストで合理的に準備出来る。
従って、本発明は、中低層住宅の土木基礎工事用の基礎杭として、広範囲の地層に有効に適用出来る基礎杭の提供を可能とする、実用性の高い発明である。
【図面の簡単な説明】
【図１】本発明実施例の側面図である。
【図２】本発明実施例の頭部２の外観図である。
【図３】変形例の側面図である。
【図４】本発明実施例の各掘進羽根対の配置状態説明図である。
【図５】従来例１の側面図である。
【図６】従来例２の分解斜視図である。
【符号の説明】
１：鋼管（杭本体）、１Ｔ：鋼管先端、
２：頭部、２Ｂ：基端（頭部基端）、
２０：円筒部、２１：円錐ヘッド（裁頭円錐ヘッド）、
２２：突出胴
２３，２３´：掘進羽根（１段目掘進羽根）、
２３Ｔ：羽根先端、２４，２４´：切削羽根（切削刃）、
２４Ｂ：基端（羽根基端）、２４Ｔ：先端（羽根先端）、
２５：当接片、
２６，２６´：掘進羽根（２段目掘進羽根）、
２７，２７´：掘進羽根（３段目掘進羽根）、
Ｓ：間隔（スペース）、Ｄ１：鋼管外径（外径）、
Ｄ２０：円筒部外径（外径）、
Ｄ２３：掘進羽根外径（外径）、Ｄ２４：切削羽根外径（外径）、
Ｚ２３：掘進羽根領域（配置領域）、Ｚ２４：切削羽根領域（配置領域）、
Ｐ：鋼管杭（杭）[0001]
BACKGROUND OF THE INVENTION
The present invention is a foundation pile for buildings and warehouses such as middle- and low-rise apartments and condominiums. More specifically, the pile has a cutting blade (cutting blade) and a support blade (digging blade) at the tip of the pile, and the pile is pressed downward. The pile can be piled on the desired support layer by vibration-free, noise-free and soil-free, and belongs to the technical field of building foundation work.
[0002]
[Prior art]
[Patent Document 1]
Japanese Examined Patent Publication No. 2-62648
[Patent Document 2]
Japanese Utility Model Publication No. 4-39293
[Conventional example 1 (FIG. 5)]
Japanese Patent Publication No. 2-62648 has proposed a steel pipe pile provided with a drilling blade and a spiral blade.
That is, as shown in FIG. 5, the tip of the steel pipe pile main body is closed with a bottom plate, two pieces of excavation blades are projected downward on the bottom plate, and the lower end of the pile main body is along the outer peripheral surface. A spiral wing having a large wing width is provided over approximately one turn.
[0003]
Then, it is pressed into the ground while rotating so as to be screwed into the soft ground, the soil at the tip of the pile body is softened by excavation with the excavating blade at the lower end, and the spiral wing is engulfed in the unexcavated soil on the side of the pile, While the pile body is rotated and propelled using the proof stress as a reaction force, the excavated and softened earth and sand are extruded and compressed to the side of the pile, and the pile body is screwed into the ground without draining soil.
[0004]
[Conventional example 2 (FIG. 6)]
Also, Japanese Utility Model Publication No. 4-39293 proposes a conical portion with the tip of the screwed pile as a conical portion and a large number of blades attached thereto.
That is, as shown in FIG. 6, the pile member is filled with concrete inside, and a female screw member is arranged at the lower end and a male screw member is arranged at the upper end so that the connection can be made longer. The inside of the larger tip shoe is filled with concrete, and a male screw member is projected from the center of the upper end. A large number of blades are attached in a spiral form on the outer periphery of the shoe, and the shoe is screwed to the tip of the pile member. They are fixed together to make a screwed pile.
[0005]
Then, the pile member is screwed into the ground while rotating the upper end of the pile member, and the new pile member is screwed and screwed to increase the joint strength at the joint between the pile members. It is easy to penetrate the pile member into the ground by the tip shoe having a diameter.
[0006]
[Problems to be solved by the invention]
Although the thing of the prior art example 1 (FIG. 5) can be piled without vibration, no noise, and no soil, the spiral wing having the outer diameter of about 2 to 3 times the outer diameter of the pile body is used as the inner circumference. Wrapping and welding the outer periphery of the steel pipe to the outer periphery of the steel pipe is a complicated and difficult task requiring skill, and the welding attachment of the bottom plate to the steel pipe end and the welding attachment of the excavating blade to the bottom plate are also complicated operations.
[0007]
And since the tip is a bottom plate and there are excavation blades on the outer periphery of the bottom plate, if there is a hard formation in a shallow place of the ground, or if there is no particularly hard formation up to the support ground, When there is an obstacle such as a rock mass, the bottom plate at the tip of the pile cannot penetrate the obstacle, and the pile cannot be driven to a predetermined ground depth.
In addition, since the spiral blade has a continuous pitch of 1 pitch, the digging entry point (spiral blade lower end) is only one point on the outer periphery, and the tip is the bottom plate, so that the pile 1 is misaligned during digging. Easy and smooth excavation cannot be expected.
[0008]
Further, even in the conventional example 2, the welding attachment of the enlarged diameter blade to the outer periphery of the pile member and the welding attachment of the blade to the outer shell surface of the tip shoe are complicated and skillful as in the conventional example 1. Even if trying to cast a mold, the mold framework is very complicated and difficult due to the outer shape of the tip shoe and the arrangement of many blades. It is difficult to manufacture a tip shoe having a uniform strength, and the manufacturing cost increases.
[0009]
And, since the outer diameter of the tip shoe is larger than the pile member outer diameter of the pile body, when the pile is driven, the soil on the outer peripheral surface of the pile body is cut by the tip shoe and penetration of the pile member becomes easy, Since the soil of the outer periphery of the pile member is cut, the frictional support force of the outer peripheral surface of the pile member as a friction pile is reduced.
Moreover, since the tip shoe has a conical shape, it is difficult to detect and grasp the change in the hardness (N value) of the ground during excavation work.
[0010]
The present invention solves or improves the problems of these friction piles, can be manufactured at a low cost, and exhibits a cutting force that can be piled at a predetermined position even in soils where there are boulders and rocks. Provided is a steel pipe foundation pile having a novel head that can easily reach the N value and exhibits a strong pile supporting force.
[0011]
[Means for solving the problems and actions]
  The steel pipe pile P of the present invention is a pile P in which a head 2 composed of a truncated cone head 21 having a cylindrical portion 20 and a tip surface Ts is fitted and fixed to the tip of a steel pipe 1, for example, as shown in FIG.The head 2 includes a protruding barrel 22 for fitting into the steel pipe 1 at the base end 2B of the cylindrical portion 20, and includes contact pieces 25 at appropriate intervals on the protruding barrel peripheral surface of the base end 2B.In the cylindrical part 20,eachThe digging blades 23 and 23 ′ are attached to the conical head 21.EachThe cutting blades 24, 24 'are arranged in such a manner that each of the digging blades and each of the cutting blades are inclined in a substantially half-circumference on the outer peripheral surface and rotationally symmetrical by 180 °.
[0012]
Note that “180 ° rotational symmetry” means that the same form appears when rotated 180 ° with respect to the axis XX in FIG. 1. For example, in FIG. The excavation blade 23 and the cutting blade 24 are exposed in a left-down manner, and the excavation blade 23 'and the cutting blade 24' are in a right-down manner on the back side, but the head is rotated 180 ° around the axis XX. If so, it means that the rear digging blade 23 ′ and the cutting blade 24 ′ are exposed and occupy the positions of the digging blade 23 and the cutting blade 24 of FIG. 1.
[0013]
In addition, the inclination angle of the digging blades 23 and 23 ′ and the inclination angle of the cutting blades 24 and 24 ′ are determined as necessary, and the cylindrical portion 20 is rotated when the pile P is rotated, that is, when the head 2 is rotated. The upper excavation blades 23 and 23 ′ may cut the pile P, and the cutting blades 24 and 24 ′ on the conical head 21 may cut the ground at the tip of the pile.
Further, the tip surface Ts facilitates detection of a pressure change at the time of penetration of the pile, and is a small area plane having a diameter of 5 to 10 cm in order to suppress an increase in penetration resistance to a minimum. Is preferred.
[0014]
Therefore, in order to fit and fix the head 2 to the tip of the steel pipe 1, the head 2 may be cast as a separate body and welded to the steel pipe. Can be produced.
Moreover, since each digging blade | wing 23,23 'arrange | positioned on the outer peripheral surface of the head 2 and the cutting blades 24 and 24' are substantially half-circular blades symmetrical with 180 degrees, the head 2 is easily used using a two-part type. Can be cast.
[0015]
Further, since the head 2 has the tip surface Ts at the tip, the tip surface Ts acts as a pressure receiving surface for the penetration resistance force during the excavation work, so that it is easy to detect a change in the resistance force of the soil, and the excavation is performed. Foundation piles that can sense the increase of N value during work as an increase in auger torque load, make it easy to drive each pile up to the support layer of the specified N value, and each pile has a uniform support force Driving construction is possible.
[0016]
Moreover, since each blade | wing 23,23 'and 24,24' is 180 degree symmetrical arrangement | positioning in a substantially half circumference, ie, a division symmetrical arrangement, arrangement | positioning area length Z23, Z24 of the blade | wing 23,24 on a head is as follows. It can be accommodated within ½ length of the blade length arrangement area in the continuous spiral form, that is, it can accommodate the blade for one spiral in the spiral half circumference, and the head 2 of limited length. There is a degree of freedom in setting the inclination angle of each blade above, and it can be arranged so that no clogging occurs between the digging blades 23 and 23 ', and between the cutting blades 24 and 24' can be an inclination angle for improving the cutting force. .
[0017]
In addition, since the excavating blades 23 and 23 'and the cutting blades 24 and 24' are symmetrical with each other, the excavating action stress and the cutting action stress cooperate with each other with 180 degree symmetry when the pile P is rotated and pushed. Since the same cutting and excavation action occurs at two places at the same level position of the natural ground, the cutting and excavation action of the pile P becomes smooth.
[0018]
  Further, in the pile P of the present invention, the cylindrical portion 20 of the head 2 is provided with a projecting cylinder 22 for fitting into the steel pipe at the base end, and abuts the projecting cylinder peripheral surface of the base end 2B at an appropriate interval. It has a piece 25It is essential toAs shown in FIG. 1, the contact piece 25 acts as a contact stopper to the head 2 base end 2B of the tip 1T of the steel pipe 1, and each contact piece 25 contacts the steel pipe tip in the same form. Moreover, it is preferable that the abutment pieces 25 have at least the same projecting dimension a from the base end 2B.
[0019]
Therefore, the fitting of the head 2 to the tip of the steel pipe is easy by fitting the protruding cylinder 22, and the interval S on the protruding cylinder 22 having a width a (abutting piece protruding dimension) formed by the abutting piece 25 is set. By welding the gap S including the abutment piece 25 flush with the pile diameter D1, as the welding allowance, the head 2 and the steel pipe 1 can be welded uniformly and firmly. Production of the steel pipe pile P becomes easy.
[0020]
  The steel pipe pile 2 of the second invention is a pile P in which a head 2 composed of a truncated cone head 2 having a cylindrical portion 20 and a tip surface Ts is fitted and fixed to the tip of the steel pipe 1, for example, as shown in FIG. There, yenTube part 20 for eachThe digging blades 23, 23 ′ have a spiral arrangement of approximately ½ circumference of the gentle inclination angle θ 23, and the conical head 21On top of eachThe cutting blades 24, 24 'are arranged in a spiral arrangement with a half of a steep inclination angle θ24.The digging blades 23 and 23 ′ and the cutting blades 24 and 24 ′ are arranged 180 ° rotationally symmetrically on the outer peripheral surface.
  In this case, even if the digging blades 23 and 23 'having the gentle inclination angle θ23 rotate without breaking the ground and generate a thrust force on the pile P, the rotation of the cutting blades 24 and 24' having the steep inclination angle θ24 is the tip of the pile. The cutting force of the natural ground is produced by generating a cutting force on the natural ground.
[0021]
  Therefore, coupled with the action of the cone head 21 having the tip area Ts having a small area, the cone head 21 is plunged into the ground, and the cone 20 is cut and cut off by the cone head 21. With this thrust generating action, the steel pipe pile P can be smoothly piled in the formation where there is a boulder or rock mass without softening the ground on the outer peripheral surface of the pile P. P exhibits a necessary and sufficient support force by a large support force for the digging blades 23 and 23 ′ to be gently inclined and a friction support force on the outer peripheral surface of the steel pipe pile P.
[0022]
  Further, the outer surface of the contact piece 25 is flush with the outer periphery of the cylindrical portion 20, and the protruding body 22 of the head 2 base end is fitted into the steel pipe 1 to form the head base end 2 </ b> B formed by the contact piece 25. It is convenient for fitting and fixing the head 2 and the steel pipe 1 to weld the gap S between the steel pipe tip 1T and the steel pipe tip 1T.
  In this case, it is easy to form the mold of the contact piece 25, and it is easy to perform a flush welding operation within the interval S during welding, and strong welding integration is possible.
[0023]
  Moreover, in this invention steel pipe pile P, the outer diameter D20 of the cylindrical part 20 is the same diameter as the outer diameter D1 of the steel pipe 1, and the outer diameter D23 of the digging blades 23 and 23 'is substantially 1 of the steel pipe outer diameter D1. The outer diameter D24 of the cutting blades 24 and 24 'is preferably equal to or less than the outer diameter D1 of the steel pipe.
  In this case, since the outer diameter D20 of the cylindrical portion 20 is the same as the outer diameter D1 of the steel pipe, the penetration of the pile P becomes smooth, and the digging blades 23 and 23 'function as support blades after pile driving. If the diameter D23 is 1.5 times or more of the steel pipe outer diameter D1, the supporting force can be exerted, and if the outer diameter D23 is twice or more the steel pipe outer diameter D1, the excavation rotational load becomes strong, causing a problem in workability. Therefore, D23 = 1.5-2D1 is preferable from the viewpoint of workability and pile supportability.
[0024]
  And since the cutting blades 24 and 24 'cut and soften the ground at the tip of the pile, when the outer peripheral portion of the steel pipe 1 is cut and softened, the frictional support force on the side peripheral surface of the pile P is extremely reduced. It is preferable to keep the working range of the blades 24, 24 'within the pile outer diameter D1.
  Therefore, if the cylindrical part outer diameter D20, the steel pipe outer diameter D1, the digging blade outer diameter D23, and the cutting blade outer diameter D24 are set to the above conditions, a necessary and sufficient supporting force can be obtained under a reasonable pile rotational stress. A smooth driving operation of the foundation pile P can be performed.
[0025]
Further, it is preferable that the blade width W24 of each cutting blade 24, 24 ′ is gradually increased from the base end 24B to the tip 24T.
The conical head 21 in which the cutting blades 24 and 24 ′ are arranged has a shallow hard layer, a boulder, and a rock mass due to the conical circumferential surface having the tip surface Ts and the cutting blades 24 and 24 ′ on the conical circumferential surface. The length L21 of the conical head 21 is preferably suppressed to a length substantially equal to the conical head diameter, that is, the cylindrical portion diameter D20 from the strength surface.
[0026]
In this case, if the width W24 of the cutting blades 24, 24 'is gradually increased from the base end 24B to the tip 24T, a pair of long cuttings with a relatively steep inclination angle θ24 on a conical surface having a relatively short conical head length L21. The blades 24 and 24 ′ can be arranged 180 ° symmetrically, and the long blades 24 and 24 ′ can be mounted within a dimension in which the cutting blade diameter D 24 does not exceed the steel pipe pile diameter (steel pipe diameter) D 1.
[0027]
Accordingly, the conical head 21 does not reduce the ground friction force on the outer peripheral surface of the steel pipe pile P, that is, without cutting the outer layer on the outer peripheral surface of the steel pipe pile P, the pile tip within the range of the steel pipe diameter D1. It is possible to exert a powerful cutting action on the natural ground, and the steel pipe pile P can be piled regardless of the hardness of the formation at a predetermined pile driving place, and the excavation blades 23 and 23 'of the head 2 and the steel pipe It becomes the steel pipe pile which exhibits sufficient support power with the frictional force of the outer peripheral surface of the excavation blades 26, 26 '; 27, 27' on 1 and the pile main body (steel pipe 1).
[0028]
Further, as shown in FIG. 4, at least a pair of digging blades 26, 26 ′; 27, 27 ′ is provided on the steel pipe 1 connected to the cylindrical portion 20, and each digging blade is inclined in a substantially half-circular shape on the outer peripheral surface, Moreover, it is particularly preferable to arrange them 180 degrees rotationally symmetric.
In this case, the arrangement interval and blade diameter of the digging blade pair may be appropriately selected and determined according to the application site. However, since the digging blade functions as a pile support after driving the pile, a plurality of pairs are arranged as shown in FIG. In this case, the intervals L1 and L2 between the digging blades including the head digging blades 23 are preferably equidistant and 50 cm to 80 cm.
[0029]
Further, the digging blades can be attached to the surface of the steel pipe by welding means, and each digging blade pair is two half-blade blade pieces, so it is much easier than welding and fixing the blades of one spiral. In addition, it is possible to arrange excavation blades according to the geology at the foundation pile driving site, and it is possible to rationally drive piles with sufficient supporting force according to the geology.
[0030]
Further, as shown in FIG. 4, it is preferable that the digging blade diameters D26 and D27 on the steel pipe 1 are larger than the digging blade diameter D23 on the cylindrical portion 20.
In general, in the ground, there may be a part that causes driving resistance to the pile in the middle of the predetermined support layer with the necessary bearing capacity (N value) according to the size of the building. Since the blades are at risk of damage, it is advantageous to reduce the diameter D23 of the head digging blade to compensate for the decrease in pile bearing capacity with the large diameter digging blade on the steel pipe.
[0031]
Therefore, the pair of excavation blades of the pile can suppress the excavation damage because the excavation blades 23 and 23 ′ of the head for excavating the partial hard soil together with the cutting blade 24 of the head have a small diameter, so that the excavation damage can be suppressed. It is reasonable to obtain a sufficient pile support force by setting the digging blades 26, 26 ′, 27, 27 ′ having a small resistance to cutting digging to have a large diameter.
In this case, as shown in FIG. 4, it is preferable that the diameters of the digging blades D23, D26, and D27 are sequentially increased from the upper side (D23 <D26 <D27) from the viewpoint of the digging action surface and the support function surface of the digging blade. If the diameter of the digging blades D26 and D27 on the steel pipe 1 is set to 3 to 5 times the diameter of the steel pipe D1, it is possible to cope with a soft stratum, and if necessary, the digging blades on the steel pipe 1 have three or four stages. May be provided.
[0032]
[Example (FIGS. 1 and 2)]
The steel pipe 1 employs a commercially available outer diameter D1 as a steel pipe pile of 165.2 mm and a wall thickness of 5.5 mm.
The head 2 is a cast product having a general wall thickness of 10 mm. The outer diameter D20 of the cylindrical portion 20 is the same as the outer diameter D1 of the steel pipe 1, the cylindrical portion length L20 is 100 mm, and the length L21 of the conical head 21 is 155 mm. The tip is provided with a flat tip surface Ts having a diameter of 6 cm.
[0033]
Then, on the outer periphery of the cylindrical portion 20, two digging blades 23, 23 'are arranged, the inclination angle θ23 is 15 °, the digging blade outer diameter D23 is 250 mm, and the blades 23, 23' are half-circular with a thickness of 7 mm. Over the axis XX, 180 [deg.] Symmetrical, i.e., when the axis XX is rotated 180 [deg.], Before and after rotation, the digging blades 23 and 23 'appear in the same form and 180 [deg.] To place.
[0034]
Further, on the outer peripheral surface of the conical head 21, as shown in FIG. 1, the cutting blades 24, 24 'having a wall thickness of 5.5 mm are inclined with respect to the axis XX with a tilt of each θ24 of 45 °. In addition, the projecting dimension (width W24) of the cutting blade is 0 when the blade base end 24B converges at the base end 21E of the conical head 21, and gradually increases toward the tip portion from the conical circumferential surface at the most distal end 24T. The projecting width W2 is 25 mm.
[0035]
Further, as shown in FIG. 2, from the base end 2 </ b> B of the head 2, the projecting cylinder 22 has a projecting length L <b> 22 of 20 mm, a diameter D <b> 2 is a dimension (154 mm) that can be fitted and intimately inside the steel pipe 1, Four abutting pieces 25 are arranged on the base end of each of them at intervals of 90 °.
Each contact piece 25 is flush with the outer periphery of the cylindrical portion 20 and has a protruding length a of 3 mm.
[0036]
The head portion 2 having a symmetrical shape with the X-X line 180 ° is integrally cast by two-part clamping, and the projecting body 22 is closely fitted to the tip 1T of the steel pipe 1 having a predetermined length, and the head base end 2B and the steel pipe Overlay welding is performed at an interval S formed by the contact piece 25 group with the tip 1T, and the interval S is finished to be substantially flush with the contact piece 25 by welding.
Further, on the outer periphery of the steel pipe 1, the second stage digging blades 26, 26 ′ are maintained at the distance L 1 of 50 cm from the position of the digging blades 23, 23 ′ on the cylindrical portion 20 of the head 2, and the second stage digging is performed. The third digging blades 27 and 27 'are fixed by welding while maintaining a distance L2 of 50 cm from the blade.
The second stage digging blade diameter D26 is 40 cm, and the third stage digging blade diameter D27 is 45 cm, but the inclination angles θ23, θ26, θ27 and blade thickness of each digging blade are the same.
[0037]
[Example effects]
The head 2 of the pile P of the present invention includes a cylindrical portion 20 having half-peripheral digging blades 23 and 23 ′ having a gentle inclination (15 °) on the outer peripheral surface in a cross-over configuration, and a half-periphery of a steep inclination (45 °). A conical head provided with cutting blades 24, 24 'on the outer peripheral surface in a cross-back form and a complicated form in which the outer shape protruding from the cylindrical body base end 2B and the protruding cylinder 22 provided with the contact piece 25 is 180 ° rotationally symmetric However, since it is 180 ° rotationally symmetric, it is easy to mold and remove the mold by the two-divided mold, and casting is easy.
In addition, the attachment of the head 2 to the steel pipe tip 1T can be easily performed by firmly fitting and fixing the gap S as a welding allowance by inserting and fitting the protruding body 22 and forming the gap S by the contact piece 25. .
[0038]
Moreover, since the digging blades 23 and 23 'of the head 2 and the digging blades 26 and 26'; 27 and 27 'on the steel pipe 1 are all inclined at the same angle, and the cutting blades 24 and 24' are steeply inclined. Even when the steel pipe pile P is excavated, the cutting blades 24, 24 'can perform the cutting scraping action so that the excavation blade does not cut the ground, and the pile at the tip of the pile P has a diameter D1. Is cut only within the range of the steel pipe pile P by the excavating blades 23, 23 '; 26, 26'; Propulsion driving can be carried out smoothly.
[0039]
And since the digging blades 23 and 23 'receiving the large digging resistance in the first stage in the advancing direction have a small diameter (about 1.5 times the steel pipe diameter D1), the breakage can be suppressed and the second stage having a relatively small digging resistance. The digging blades 26 and 26 'and the third digging blades 27 and 27' have a large diameter (3 to 5 times the steel pipe diameter D1), and each digging blade surface has a gentle inclination (15 °). Exhibits a sufficient pile support force, and the friction force due to the uncut ground on the outer peripheral surface of the steel pipe 1 and the support force of the conical head 21 having the tip surface Ts due to the support layer having a desired N value are combined. Therefore, the steel pipe pile P exhibits a necessary and sufficient supporting force as a building foundation pile.
[0040]
Moreover, since the two digging blades 23, 23 'and the two cutting blades 24, 24' are rotationally symmetrical by 180 °, two half-pitch length blades are respectively provided in the spiral half-circumferential pitch regions Z23, Z24. The same cutting action and excavation action at the same level with respect to the natural ground can always be performed 180 degrees symmetrically on both front and back sides in a narrow half-pitch area, and powerful, uniform and smooth cutting and excavation action. Play.
[0041]
Since the cutting blades 24 and 24 ′ at the tip of the pile P are present on the conical head, the rotation of the pile P proceeds with less misalignment. As a result, it is possible to cut a hard stratum, and the pile P can be drilled powerfully and smoothly.
Moreover, the presence of the tip surface Ts of the conical head 21 slightly increases the driving resistance at the tip of the pile P and makes it easy to detect changes in the pile driving resistance force. The change, that is, the change in the support force of the ground (N value change) can be grasped sharply as the change in the rotational torque, and the machine operator can accurately perform the stoppage of the pile P when it reaches the predetermined support layer. Each construction management becomes easy.
[0042]
[Modification (Fig. 3)]
The modification of FIG. 3 is the one in the embodiment (FIG. 1) in which a pair of digging blades 23 and 23 'are arranged in two upper and lower stages.
That is, only the cylindrical portion 20 of the head 2 is made longer than that of FIG. 1, and blades for two spirals are arranged in one pitch of the spiral on the peripheral surface.
Therefore, the unit price of the head 2, that is, the unit price of the pile P, is higher than that of the embodiment, but the propulsive force of the pile P and the pile supporting force by the excavation blades are improved.
[0043]
[Others]
In the embodiment (FIG. 1) and the modified example (FIG. 3), the cutting blades 24, 24 ′ are steeply inclined by 45 °, the blade width is gradually increased from the base end 24B to the tip 24T, and the excavation blades 23, 23 ′. However, it is also possible to arrange the cutting blades with the same width from the base end to the tip end with an inclination angle similar to that of the excavation blade.
In this case, the cutting blade arrangement region Z24 is shorter than that of the embodiment, and the blade pieces 24 and 24 'which are shortened are arranged in the middle portion of the circumferential surface of the conical head 21. Since the rotation is propelled around the surface Ts, it is possible to cut the natural ground at the tip of the pile by the cooperative action of the head tip surface Ts, the inclined circumferential surface of the conical head 21 and the tips of the cutting blades 24, 24 ′.
[0044]
Further, if the wall thickness is tapered over the tip width W24 of each cutting blade 24, 24 'and the entire tip width W23 of the digging blades 23, 23', the biting into the natural ground becomes smoother.
Moreover, although the outer diameter D23 of the digging blades 23 and 23 ′ (first-stage digging blades) is 1.5 times the outer diameter D1 of the steel pipe 1 in the embodiment, in order to increase the pile supporting force at the blade width W23. In addition, the outer diameter D23 of the digging blades 23 and 23 'can be increased as required within the scope of the present invention, and can be twice or more than the steel pipe diameter D1.
Moreover, although the diameter of each digging blade was set to D23 <D26 <D27 in the Example, the diameters D26 and D27 of the digging blades 26 and 26 '; 27 and 27' on the steel pipe 1 may be the same. In addition, the tip surface Ts of the conical head 21 is 6 cm in the embodiment, but it is preferable that the tip surface Ts is smaller from the surface of the pile misalignment suppression, and it is possible to detect the excavation rotational torque change depending on the machine used for driving the pile. The minimum plane may be used.
[0045]
【The invention's effect】
The conical head 21 is provided with cutting blades 24, 24 ′ on the circumferential surface thereof, and the head 2 provided with the digging blades 23, 23 ′ on the circumferential surface of the cylindrical portion 20 is fitted and fixed to the tip of the steel pipe 1. Since the pile for cutting and excavation can be formed simply by fixing the necessary excavation blades, only the complex head 2 is manufactured as a separate product with the necessary functions, and manufactured separately from the steel pipe 1, The stockpile can be stored, and the steel pipe pile P can be stored and manufactured easily.
[0046]
In addition, since the head 2 has the cutting blades 24, 24 ′ and the digging blades 23, 23 ′ having substantially a half circumference arranged on the outer peripheral surface of the head in a 180 ° rotational symmetry, the blade arrangement is a spiral 1. / 2 One-long blades can be placed within the pitch, and the blades can be placed compactly in the short placement zones Z23, Z24, and each cutting blade and each digging blade are 180 ° at the same level position in the ground. Combined with the action at two rotationally symmetric places, strong and smooth cutting and digging action can be exhibited in the short cutting zone Z24 and the digging zone Z23.
Furthermore, since the tip surface Ts which receives penetration resistance exists in the head of the conical head 21, a change in penetration resistance force into the soil when the pile P is driven can be detected by the operator. Therefore, it is possible to accurately grasp the arrival to the support layer having a predetermined N value, and it is possible to perform the uniform driving construction of all the driving piles P.
[0047]
Further, the cutting blades act under the rotation without lateral shaking on the inclined peripheral surface of the conical head, and the cutting blades 24T and the excavation blade tip 23T, which are arranged in a 180 ° rotational symmetry, are bitten into the ground. As a result, powerful and smooth cutting and excavation are possible.
[0048]
Moreover, since the form of the head 2 fixed to the steel pipe 1 is 180 [deg.] Rotationally symmetric, its complicated shape can be integrally cast by a two-part mold clamping, and the mold assembly and the mold dividing work after casting are easy. Yes, steel pipe piles that exhibit strong cutting force and excavation power can be reasonably prepared at low cost.
Therefore, the present invention is a highly practical invention that makes it possible to provide a foundation pile that can be effectively applied to a wide range of strata as a foundation pile for civil engineering foundation work in medium- and low-rise housing.
[Brief description of the drawings]
FIG. 1 is a side view of an embodiment of the present invention.
FIG. 2 is an external view of a head 2 according to an embodiment of the present invention.
FIG. 3 is a side view of a modified example.
FIG. 4 is an explanatory diagram of an arrangement state of each digging blade pair according to the embodiment of the present invention.
5 is a side view of Conventional Example 1. FIG.
6 is an exploded perspective view of Conventional Example 2. FIG.
[Explanation of symbols]
1: Steel pipe (pile body), 1T: Steel pipe tip,
2: head, 2B: proximal end (head proximal end),
20: cylindrical part, 21: conical head (conical head)
22: Protruding trunk
23, 23 ': digging blade (first digging blade),
23T: blade tip 24, 24 ': cutting blade (cutting blade),
24B: proximal end (blade proximal end), 24T: distal end (blade distal end),
25: contact piece,
26, 26 ': digging blade (second stage digging blade),
27, 27 ': digging blade (third stage digging blade),
S: Interval (space), D1: Steel pipe outer diameter (outer diameter),
D20: cylindrical portion outer diameter (outer diameter),
D23: digging blade outer diameter (outer diameter), D24: cutting blade outer diameter (outer diameter),
Z23: excavation blade region (arrangement region), Z24: cutting blade region (arrangement region),
P: Steel pipe pile (pile)

Claims

The tip of the steel tube (1), a cylindrical portion (20) and a distal face head consisting of truncated cone head having (Ts) (21) (2) a fixedly fitted to pile (P), the head (2) is provided with a projecting cylinder (22) for fitting into the steel pipe (1) at the base end (2B) of the cylindrical part (20), and at an appropriate interval on the projecting cylinder peripheral surface of the base end (2B). comprising a contact piece (25), the cylindrical portion (20) each excavating blades in (23,23'), the conical head (21) of each cutting blade (24, 24 '), each of excavation blades (23 , 23 ′) and steel blade foundation piles arranged so that each of the cutting blades (24, 24 ′) is in a substantially half-circular inclined form on the outer peripheral surface and is 180 ° rotationally symmetric.

A pile (P) in which a head (2) composed of a truncated cone head (21) having a cylindrical portion (20) and a tip surface (Ts) is fitted and fixed to the tip of a steel pipe (1), the cylindrical portion In (20) , each digging blade (23, 23 ') is in a spiral arrangement of approximately 1/2 round with a gentle inclination , and each cutting blade (24, 24') is steeply inclined in the conical head (21) . in about 1/2 round spiral arrangement, the boring blade (23,23') mutually, and each cutting blade (24, 24 ') each other, in 1 80 ° rotational symmetry on the outer peripheral surface, the arranged steel foundation piles.

The outer surface of the contact piece (25) is flush with the outer periphery of the cylindrical portion (20), and the protruding barrel (22) at the base end of the head (2) is fitted into the steel pipe (1), and the contact piece (25 The steel pipe foundation pile according to claim 1 , wherein a gap (S) between the head base end (2B) and the steel pipe front end (1T) formed by welding is piled up.

The outer diameter (D20) of the cylindrical portion (20) is the same as the outer diameter (D1) of the steel pipe (1), and the outer diameter (D23) of the digging blade (23, 23 ') is the outer diameter (D1) of the steel pipe. Either of Claims 1 or 3, which is approximately 1.5 to 2 times the diameter, and the outer diameter (D24) of the cutting blade (24, 24 ') is equal to or less than the outer diameter of the steel pipe (D1). Steel pipe foundation pile according to item 1.

The steel pipe foundation pile according to any one of claims 1 to 4 , wherein the blade width (W24) of each cutting blade (24, 24 ') is gradually increased from the base end (24B) to the tip end (24T).

At least a pair of digging blades (26, 26 '; 27, 27') is attached to the steel pipe (1) connected to the cylindrical portion (20), and each digging blade is inclined in a substantially half-circular shape on the outer peripheral surface, and The steel pipe foundation pile of any one of Claims 1 thru | or 5 arrange | positioned 180 degrees rotationally symmetric.

The steel pipe foundation pile according to claim 6, wherein the diameter of the digging blade (D26, D27) on the steel pipe (1) is larger than the diameter of the digging blade (D23) on the cylindrical portion (20).