【０００１】
【発明の属する技術分野】
本発明は、例えば地盤の弱い土地に住宅等の建築物を建てるときに地中に埋設する金属製の杭に係り、特に、埋設時の貫入抵抗が少なく、低騒音で埋設でき、製造が容易な回転埋設杭と、この回転埋設杭の先端部材に関する。
【０００２】
【従来の技術】
従来、この種の鋼管杭等の埋設施工では、一般的な打撃工法、圧入工法、プレボーリング工法や中掘り工法に代わって、振動や騒音の少ない回転埋設式のねじ込みによる工法が用いられるようになってきた。
【０００３】
このようなねじ込みによる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、この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巾の大きな杭ネジ込用の螺旋翼を、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圧し圧縮し、無排土で地中に杭体をネジ込んでゆくことを特徴としている（例えば、特許文献１参照）。
【０００４】
また、パイプで形成された杭本体の先端を円板で閉塞し、この閉塞板の表面に、これと平行して複数枚の板状の切削刃を重ねて放射状に接合し、且つこの切削刃の側面を、杭本体の回転方向側に張り出した凸曲面で形成している回転埋設杭がある（例えば、特許文献２参照）。
【０００５】
【特許文献１】
特公平２−６２６４８号公報（特許請求の範囲、第１図）
【特許文献２】
特開２００１−２２６９６０号公報（特許請求の範囲、図１）
【０００６】
【発明が解決しようとする課題】
ところで、前記埋設工法に使用する鋼管杭は、杭本体の下端に底板を溶接により固設し、杭本体の下端部外周面に杭ネジ込用の螺旋翼を、ほぼ一巻きにわたり溶接により突設するため、構成が複雑であると共に、溶接個所が多いため製造が煩雑となる問題点があった。特に、螺旋翼を杭本体の外周に螺旋に沿って溶接することは、作業が煩雑となっていた。
【０００７】
また、前記の鋼管杭は、所定の長さを有する杭本体に螺旋翼を溶接したものであり、支持地盤が浅い位置にある場合は鋼管杭の上部を短く切断してから埋設している。このように所定長の長い鋼管杭を必要な長さに切断するため、切断された上方の端部は不要物となって廃棄していた。
【０００８】
本発明は、このような問題に鑑みてなされたものであって、その目的とするところは、製造が容易で、パイプ状の杭本体の先端に容易に連結固定できる回転埋設杭の先端部材と、この先端部材を所望の長さに切断した杭本体に連結固定し、支持地盤の深さに合わせて地中に容易に埋設できるねじ込み式の回転埋設杭を提供することにある。
【０００９】
【課題を解決するための手段】
前記目的を達成すべく、本発明に係る回転埋設杭の先端部材は、回転埋設杭を構成する杭本体の地中に貫入する側の先端に連結固定される先端部材であって、円筒状の中心胴部と、該中心胴部の外周面に形成した傾斜板部とを備えることを特徴とし、中心胴部の外周に１枚又は複数枚の傾斜板部を形成すると好適である。
【００１０】
前記のごとく構成された本発明の回転埋設杭の先端部材は、軸方向の長さが短い円筒状の中心胴部の外周面に傾斜板部を形成するため、長い杭の先端に傾斜板部を形成する場合と比較して溶接等の溶着作業が容易となり、この先端部材に任意の長さのパイプ状の杭本体を連結固定することで、所望の長さの回転埋設杭を容易に製造することができる。この結果、従来の長尺の鋼管杭のように、切断したパイプ状部分の廃棄を無くすことができる。
【００１１】
また、本発明に係る回転埋設杭の好ましい具体的な態様としては、前記中心胴部は、下端開口に円板部が形成され、該円板部の下面に先端突部が突設されたことを特徴としている。先端突部は半円形、円弧の一部、傾斜辺を有する板材で構成すると好適である。この構成によれば、回転埋設杭を埋設する際、地表に先端突部を突き刺して位置決めできるので、回転埋設杭の埋設時の振れを防止して所定の場所に正確に埋設できると共に貫入抵抗を少なくできる。
【００１２】
さらに、本発明に係る回転埋設杭の好ましい具体的な他の態様としては、前記中心胴部は、連結される杭本体の下端が挿入される段差部を備えることを特徴とする。この構成によれば、杭本体の下端を先端部材の段差部に挿入した状態で溶接等により連結固定できるため、杭本体と先端部材とを必要な長さだけ重ねて精度良く連結固定できるため、回転埋設杭の品質を高めることができる。
【００１３】
本発明に係る回転埋設杭の好ましい具体的なさらに他の態様としては、前記先端部材は、鋳造により一体に形成されること、又は各部材が溶着により一体に形成されることを特徴とする。鋳造により形成すると、中心胴部と、その外周面に形成した傾斜板部とを、さらに円板部や先端突部を含めて鋳造により一体に形成できるため先端部材の製造が容易に行え、また鋳造時に使用する鋳型を小型化することができる。また、中心胴部や傾斜板部等の各部材を溶着により一体に形成すると鋳型を必要とせず、特に少数の製造に適している。
【００１４】
本発明に係る回転埋設杭は、前記したいずれかの先端部材を、パイプ状の杭本体の先端に連結固定したことを特徴とする。先端部材と杭本体との固定は、溶接による溶着や、ボルト止め等で行うことができる。このように構成された本発明の回転埋設杭は、支持地盤の深さや必要な長さに合わせて杭本体を所望の長さに切断し、切断された杭本体の端部に先端部材を連結固定して、所望の長さに設定された回転埋設杭を容易に製造することができる。また、先端部材と杭本体とを連結固定する溶接面は、杭本体の軸心と直交する水平面に沿う１周であるため、容易に溶接できる。
【００１５】
【発明の実施の形態】
以下、本発明に係る回転埋設杭の一実施形態を図面に基づき詳細に説明する。図１（ａ）は、本実施形態に係る回転埋設杭の分解した状態の要部斜視図、（ｂ）は連結した状態の回転埋設杭の要部正面図、図２（ａ）は図１の回転埋設杭の先端部材の正面図、（ｂ）は（ａ）の底面図、（ｃ）は（ｂ）のＡ−Ａ線断面図、図３は、先端部材を下方から見た斜視図である。
【００１６】
図１〜３において、回転埋設杭１は、鋼管から形成される上部のパイプ状の杭本体１０と、杭本体１０の下部に溶接等により連結固定される先端部材２０とから構成され、任意の長さの杭本体１０の下端に、すなわち回転埋設杭１の地中に貫入する側の先端に、先端部材２０を連結固定して所望の長さの回転埋設杭１とすることができる。
【００１７】
杭本体１０の外径は要求される地盤の支持力によって設定され、例えば外径は１００〜３００ｍｍ程度の範囲で、肉厚は４〜８ｍｍ程度の範囲に設定される。杭本体１０の下端は、軸心と直交する一平面に沿って切断され、パイプ材を軸方向と直交する方向に輪切りにして形成される。このため、下端面１１は特殊加工が不要で、単に切断するのみで加工が完了し、所望の長さに容易に切断できる。杭本体１０の上面１２は平坦面で形成される。上面１２に近接して内部には図示していないが、この回転埋設杭１を地中にねじ込んで埋設するときに回転力を付与する複数の突起を形成してもよく、上面１２に切欠きを設けてもよい。杭本体１０は一般構造用炭素鋼等の鋼管から形成されることが好ましい。
【００１８】
杭本体１０の下端に連結される先端部材２０はシューとも呼ばれ、円筒状の中心胴部２１と、中心胴部の外周面に形成した２枚の傾斜板部２２，２２とを備えており、本実施形態では鋳造により一体に形成されている。そして、中心胴部２１の下端開口に水平の円板部２３が形成されて閉塞され、下端の水平面に底面視が十字型の先端突部２４を備えている。中心胴部２１の開口側（上方）の内周には、杭本体１０の下端が挿入される段差部２５が形成されている。段差部２５は薄肉に形成され、その内径は杭本体１０の外径より僅かに大きく形成され、杭本体１０を容易に挿入できものである。そして、段差部２５の外周壁面には垂直方向、すなわち軸方向に４本のスリット２６が形成されている。なお、円板部２３は貫通孔を有して下端開口を閉塞しないものでもよい。
【００１９】
２枚の傾斜板部２２，２２は略同一形状であり、図２（ｂ）に示すように、平面視でそれぞれ半円形状をしている。傾斜板部２２は回転埋設杭１を、例えば右方向（時計方向）に回転させたとき、地中に食い込んで回転埋設杭１が地中に入り込んでいくようにしたものであり、反時計方向に上昇する傾斜面となっている。傾斜板部２２の外径は中心胴部２１の外径の２倍程度に設定され、肉厚は１０〜２５ｍｍ程度に設定され、１５〜２０ｍｍ程度の肉厚が好ましい。
【００２０】
２枚の傾斜板部２２，２２は共に上方から見たときに反時計方向に上昇するように形成されているため、図１（ｂ）の正面視では２枚のそれぞれが水平面から１５度程度傾斜して、相互に３０度程度で交差するような形状となっている。傾斜板部２２，２２は螺旋形状でなく、平板を傾斜した状態で中心胴部２１から突設したものであり、螺旋形のようにひねった形状でないため容易に形成することができる。また、鋳造する場合も形状が簡単であり、鋳型を容易に形成することができる。
【００２１】
下端の先端突部２４は肉厚が３０ｍｍ程度の正面視で下端が円弧状の板材が９０度で交差する形状をしており、地面に形成された埋設位置を示す十字状マークと合わせやすい形状となっている。また、この回転埋設杭１を埋設するとき、この杭１を地表に立てると先端突部２４が地面に突き刺さる形状となっている。なお、先端突部は下端が円弧状の板材を交差させたものでなく、図４に示す先端部材２０Ａのように、傾斜辺を有する三角状の板材を交差させて形成した先端突部２４Ａであってもよい。
【００２２】
回転埋設杭１は先端部材２０の中心胴部２１の段差部２５の内側に、任意の長さの杭本体１０の下端を挿入し、下端面１１が段差部２５の下端面に対接した状態に嵌合させ、嵌合された外周部分の全周を溶接し溶接部２７で連結固定する。また、必要に応じてスリット２６に沿って先端部材２０と杭本体１０を溶接することにより、周方向と軸方向に沿って接合されるため、溶接強度を向上させることができる。なお、先端部材２０と杭本体１０との連結固定は溶接に限られるものでなく、杭本体１０と先端部材２０とを連通する孔（図示せず）を形成し、この孔にボルトやピンを通して固定してもよい。
【００２３】
前記の如く構成された本実施形態の回転埋設杭の埋設動作について以下に説明する。回転埋設杭１の埋設にあたっては、図示を略した杭打ち機を用いて回転埋設杭１を地盤上に直立させ、その頭部に回転と押し込みをする駆動装置を取り付け、その駆動によって回転埋設杭１をねじ込むように回転させながら地中に押し込んで行く。地盤上に直立させるとき、先端部材２０の下端の十字型の先端突部２４を地表のマーク（図示せず）等にあわせることで、埋設位置に回転埋設杭１を正確に位置合わせすることができる。
【００２４】
駆動装置により回転埋設杭１を垂直状態に立てると、先端突部２４が地表に突き刺さる。この状態で回転埋設杭１に時計方向の回転力を付与して押圧すると、回転埋設杭１の先端が振れることなく、先端に連結された先端部材２０の傾斜板部２２，２２が地中に切り込んで地中に進入していく。地中に進入していくとき、先端突部２４の下方の土砂は掘削軟化されて外周側に排除され、中心胴部２１の外周面側に圧縮される。そして圧縮された土砂を傾斜板部２２，２２が切り込んで進んでいくため、傾斜板部は圧縮土砂内に位置して支持力を高めることができる。
【００２５】
回転埋設杭１は押圧状態で回転されることによって傾斜板部２２，２２が地中にねじ込まれるため、振動や騒音の発生を少なく抑えることができ、先端突部２４で土砂を掘削軟化することで貫入抵抗を少なくすることができる。また、埋設時に廃土が発生しないため、廃土処理を省略でき施工が容易となる。埋設後は、回転埋設杭１は杭本体１０の直径より大きい外径の傾斜板部２２，２２で地中に支持されるため、杭本体１０を単体で用いたときの支持力に対して大きい支持力を得ることができる。しかも、回転埋設杭１は埋設時に地盤を緩ませることが少ないため、地盤の力を十分に生かす形で支持力を発揮させることができる。
【００２６】
前記した実施形態では、杭本体は先端部材の内側に挿入され連結固定される例を示したが、杭本体１０と先端部材２０とは図５に示すように連結することができる。図５ａの回転埋設杭１Ａの場合は、先端部材２０の円筒状の中心胴部２１の直径と、杭本体１０Ａの外径とが等しく設定されており、両者は突き合わされて例えば溶接により連結固定される。また、図５ｂの回転埋設杭１Ｂの場合は、先端部材２０の円筒状の中心胴部２１の外周に、杭本体１０Ｂの内径が外嵌し、所定の範囲だけ嵌め込んだ状態で溶接等により連結固定される。さらに図示していないが、先端部材の外周に杭本体を外嵌する場合、中心胴部の外周に段差部を設けて外嵌するように構成してもよい。なお、杭本体を構成する鋼管は、一般的に外径基準となっているため、図１のように先端部材２０の中心胴部２１に杭本体１０が挿入されることが好ましい。また、図５の例では中心胴部にはスリットのない例を示したがスリットはあってもよく、段差部を形成したが段差部は必ずしも必要でない。
【００２７】
さらに、前記の実施形態では、先端部材２０の円筒状の中心胴部２１の外周に形成された傾斜板部２２は傾斜状態の平板で構成したが、図６に示すように傾斜平板でなく螺旋板２２Ａで形成してもよい。このように傾斜板部を螺旋板２２Ａで構成すると、螺旋板は中心胴部から放射方向に水平に突出するため地盤の支持力を高めることができる。この先端部材２０Ａの下端開口には、円板部２３Ａが溶接により溶着され、円板部の中心には小径の開口２３ａが形成されている。そして、円板部の下面には略台形状の先端突部２４Ａが突設されている。この先端突部は、この先端部材を連結した回転埋設杭を地中に埋設するとき先ず地表に突き刺すことができ、杭に回転を与えるときに下端が振れることを防止できると共に土砂を掘削軟化でき、安定して埋設できる。
【００２８】
つぎに、本発明の他の実施形態を図７，８に基づき詳細に説明する。図７は本発明に係る先端部材の他の実施形態の斜視図と、先端部材と杭本体との位置関係を示す要部正面図、図８は杭本体と先端部材とを連結固定した状態の要部断面図である。なお、この実施形態は前記した実施形態に対し、中心胴部の下端が開口していることを特徴とする。そして、他の実質的に同等の構成については同じ符号を付して詳細な説明は省略する。
【００２９】
図７，８において、先端部材２０Ｂは、回転埋設杭の地中に貫入する側の先端に連結固定されるものであり、円筒状の中心胴部２１Ｂと、この中心胴部の外周面から突設する傾斜板部２２，２２とを鋳造により一体に形成してあり、中心胴部２１Ｂは下方が開口した筒状となっており、中心胴部の下端は面取りされて鋭角的に尖った先細部２１ｂとなっている。
【００３０】
中心胴部２１Ｂの上部には段差部２５が形成され、杭本体１０が挿入可能となっており、段差部２５にはスリットが形成されていない。この先端部材２０Ｂをパイプ状の杭本体１０に連結固定して回転埋設杭１Ｃとするには、杭本体１０の下端面１１を段差部２５に挿入して先端部材２０Ｂの上端と杭本体１０の外周との間を、水平の全周にわたって溶接した溶接部２７により接合して連結固定する。なお、この実施形態では、傾斜板部２２の外周端部にアール加工を施し、貫入時に土砂が傾斜板部２２の外周に逃げやすくして土砂の抵抗を減らしている。
【００３１】
この実施形態においても、先端部材２０Ｂは小型で製造が容易であり、回転埋設杭１Ｃは所望の長さの杭本体１０の下端に先端部材２０Ｂを連結固定することで、所望の長さの回転埋設杭１Ｃを容易に製造することができる。また、地中への貫入抵抗が少なく、少ない騒音や振動で埋設することができる。特に、この実施形態では、貫入時に土砂が中心胴部２１Ｂの内部に入り込むため、前記の実施形態より貫入抵抗を減らすことができる。
【００３２】
さらに、本発明の他の実施形態を図９に基づき詳細に説明する。この実施形態は、前記した実施形態と比較して先端部材は中心胴部に３枚の傾斜板部を形成してあり、中心胴部に溶接等により溶着して一体に形成されていることを特徴とするものである。
【００３３】
図９において、先端部材３０は、鋼板で形成された円筒形の中心胴部３１と、中心胴部の外周面に形成した３枚の傾斜板部３２とを備えており、傾斜板部３２はそれぞれ１２０度の開き角度を有しており、本実施形態では溶接により中心胴部３１に溶着されている。そして、下端の開口には中心孔３３ａを有する円形の鋼板製の円板部３３が溶着されている。円板部３３の下方には先端突部３４が突設されており、この先端突部３４は中央の平坦部と、その両側の傾斜部とを有している。この先端突部３４は、先端部材３０を固定した回転埋設杭を埋設するときに、地表に突き刺さることにより杭の埋設時の振れを防止すると共に、土砂を掘削して軟化させるものである。
【００３４】
図９の実施形態に示す先端部材３０も、前記の各実施形態と同様に製造が容易であり、この先端部材３０をパイプ状の杭本体１０に溶接等により連結固定して容易に所望の長さの回転埋設杭を製造できる。このように製造された回転埋設杭は埋設時に廃土が出ず、振動が少なく低騒音で近隣への被害を最小限にして埋設できる。なお、この先端部材３０も鋳造で中心胴部３１、傾斜板部３２、円板部３３、及び先端突部３４を一体に形成するようにしてもよい。
【００３５】
以上、本発明の一実施形態について詳述したが、本発明は、前記の実施形態に限定されるものではなく、特許請求の範囲に記載された本発明の精神を逸脱しない範囲で、種々の設計変更を行うことができるものである。例えば、傾斜板部は２枚、あるいは３枚設ける例を示したが、１枚でも、あるいは３枚を超える枚数でもよいことは勿論である。また、先端突部の下面は円弧部、あるいは傾斜面で形成したが平坦面で形成してもよい。杭本体と先端部材との連結固定は溶接に限るものでなく、先端部材の段差部に杭本体を挿入し、重合部分を例えばボルト締め等で固定するものでもよい。
【００３６】
先端部材は中心胴部と、その外周面から突設する傾斜板部とを備えればよく、先端が開口したものでもよい。この場合は、地盤に埋設するとき、土砂は先端部材の下端開口からパイプ状の杭本体内に流入するため、貫入抵抗を小さくすることができる。また、中心胴部の下端を閉塞する円板に代わり、逆円錐形の下方に先細となるコア部で閉塞すると、貫入時に土砂を左右に容易に振り分けることができるため、貫入抵抗を減らすことができる。
【００３７】
【発明の効果】
以上の説明から理解できるように、本発明の回転埋設杭の先端部材は、小型で製造を容易に行え、この先端部材をパイプ状の杭本体に連結固定して容易に、任意の長さの回転埋設杭を製造できる。本発明の回転埋設杭は、杭本体と先端部材とを連結固定する構成であり、所望の長さの回転埋設杭を容易に製造でき、支持地盤の深さに応じて切断した杭本体に先端部材を固定するため、杭本体の廃棄部分を無くすことができる。また、少ない貫入抵抗で地中に埋設することができ、振動や騒音の発生を抑えることができる。
【図面の簡単な説明】
【図１】（ａ）は本発明に係る回転埋設杭の一実施形態の分解した状態を示す要部斜視図、（ｂ）は連結した状態の回転埋設杭の要部正面図。
【図２】（ａ）は図１の先端部材の正面図、（ｂ）は（ａ）の底面図、（ｃ）は（ｂ）のＡ−Ａ線断面図。
【図３】図２の先端部材を下方から見た斜視図。
【図４】先端部材の他の実施形態を下方から見た斜視図。
【図５】（ａ）は先端部材の円筒部と杭本体とが突き合わせて連結固定される回転埋設杭の概略斜視図、（ｂ）は先端部材の円筒部に杭本体が外嵌して連結固定される回転埋設杭の概略斜視図。
【図６】（ａ）は傾斜板部が螺旋形で構成される先端部材の正面図、（ｂ）はその底面図、（ｃ）は（ａ）のＢ−Ｂ線断面図。
【図７】（ａ）は先端部材のさらに他の実施形態の斜視図、（ｂ）は（ａ）の先端部材と杭本体との位置関係を示す要部正面図。
【図８】図７の先端部材と杭本体とを連結固定した状態の要部断面図。
【図９】傾斜板部が３枚構成の先端部材の実施形態を示し、（ａ）は正面図、（ｂ）はその底面図、（ｃ）は（ｂ）のＣ−Ｃ線断面図。
【符号の説明】
１，１Ａ，１Ｂ，１Ｃ…回転埋設杭、１０，１０Ａ，１０Ｂ…杭本体、２０，２０Ａ，２０Ｂ，３０…先端部材、２１，２１Ｂ，３１…中心胴部、２２，２２Ａ，３２…傾斜板部、２３，２３Ａ，３３…円板部、２４，２４Ａ，３４…先端突部、２５…段差部、２７…溶接部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a metal pile to be buried in the ground when, for example, building a house or the like is built on a weak ground, and in particular, has a low penetration resistance when buried, can be buried with low noise, and is easy to manufacture. The present invention relates to a rotary buried pile and a tip member of the rotary buried pile.
[0002]
[Prior art]
Conventionally, when burying steel pipe piles of this type, instead of the general striking method, press-fitting method, pre-boring method, and digging method, a rotary buried screw method with less vibration and noise is used. It has become.
[0003]
The method of burying steel pipe piles by screwing in this way is to fix a bottom plate at the lower end of the steel pipe pile body, provide an excavation blade on this bottom plate, and attach the outer diameter of the pile body to the outer peripheral surface at the lower end of the pile body. A spiral wing for screwing a pile with a large wing width with an outer diameter of slightly more than twice is pressed into the ground while rotating so that a steel pipe pile projecting over almost one turn is screwed into soft ground. The excavation blade softens the excavated soil at the tip of the pile body, digs the spiral wings into the unexcavated soil on the side of the pile, rotates the pile as a reaction force against the strength of the soil, and piles the softened excavated soil. It is characterized in that it is pressed against the side surface and compressed, and the pile body is screwed into the ground without discharging the soil (for example, see Patent Document 1).
[0004]
Further, the tip of the pile main body formed of a pipe is closed with a disk, and a plurality of plate-shaped cutting blades are superimposed on the surface of the closing plate in parallel with each other so as to be radially joined to each other. There is a rotary buried pile having a side surface formed by a convex curved surface protruding toward the rotation direction side of the pile body (for example, see Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent Publication No. 2-62848 (Claims, FIG. 1)
[Patent Document 2]
JP 2001-226960 A (claims, FIG. 1)
[0006]
[Problems to be solved by the invention]
By the way, the steel pipe pile used for the burying method, a bottom plate is fixed to the lower end of the pile main body by welding, and a spiral wing for screwing the pile is formed on the outer peripheral surface of the lower end of the pile main body by welding over substantially one turn. Therefore, there is a problem that the structure is complicated and the manufacturing is complicated because there are many welding locations. In particular, welding a spiral blade to the outer periphery of a pile main body along a spiral has been complicated.
[0007]
Further, the steel pipe pile is formed by welding a spiral blade to a pile body having a predetermined length, and when the supporting ground is at a shallow position, the upper part of the steel pipe pile is cut short and buried. In order to cut a long steel pipe pile of a predetermined length into a required length in this way, the cut upper end is unnecessary and is discarded.
[0008]
The present invention has been made in view of such a problem, and an object thereof is to provide a tip member of a rotary buried pile which can be easily manufactured and easily connected and fixed to a tip of a pipe-shaped pile main body. Another object of the present invention is to provide a screw-type rotary buried pile which can be easily buried in the ground in accordance with the depth of the supporting ground by connecting and fixing the tip member to a pile main body cut to a desired length.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the tip member of the rotary buried pile according to the present invention is a tip member connected and fixed to the tip of the pile body constituting the rotary buried pile that penetrates into the ground, and has a cylindrical shape. It is characterized by comprising a central trunk portion and an inclined plate portion formed on the outer peripheral surface of the central trunk portion, and it is preferable to form one or a plurality of inclined plate portions on the outer periphery of the central trunk portion.
[0010]
The tip member of the rotary buried pile according to the present invention configured as described above forms an inclined plate portion on the outer peripheral surface of a cylindrical central trunk portion having a short axial length. Welding work such as welding is easier than in the case of forming a pipe. By connecting and fixing a pipe-shaped pile body of any length to this tip member, a rotary embedded pile of a desired length can be easily manufactured. can do. As a result, it is possible to eliminate the disposal of the cut pipe-shaped portion as in a conventional long steel pipe pile.
[0011]
In a preferred specific mode of the rotary buried pile according to the present invention, the center trunk portion has a disc portion formed at a lower end opening, and a tip protrusion projects from a lower surface of the disc portion. It is characterized by. It is preferable that the tip projection is formed of a plate having a semicircle, a part of an arc, and an inclined side. According to this configuration, when the rotary buried pile is buried, the tip projection can be pierced into the ground surface and positioned, so that it can be prevented from swaying when the rotary buried pile is buried, and can be accurately buried in a predetermined place, and the penetration resistance can be reduced. Can be reduced.
[0012]
Furthermore, as another preferred specific embodiment of the rotary buried pile according to the present invention, the center trunk portion is provided with a step portion into which a lower end of a connected pile main body is inserted. According to this configuration, since the lower end of the pile main body can be connected and fixed by welding or the like in a state where the lower end of the pile main body is inserted into the step portion of the tip member, the pile main body and the front end member can be overlapped by a required length and accurately connected and fixed. The quality of the rotary buried pile can be improved.
[0013]
As still another preferred mode of the rotary buried pile according to the present invention, the tip member is formed integrally by casting, or each member is formed integrally by welding. When formed by casting, the center trunk portion and the inclined plate portion formed on the outer peripheral surface thereof can be integrally formed by casting including a disk portion and a tip protrusion, so that the manufacture of the tip member can be easily performed, and The mold used for casting can be miniaturized. In addition, when the respective members such as the center trunk portion and the inclined plate portion are integrally formed by welding, a mold is not required, which is particularly suitable for a small number of manufactures.
[0014]
The rotary buried pile according to the present invention is characterized in that any one of the above-mentioned tip members is connected and fixed to the tip of a pipe-shaped pile main body. The fixing of the tip member and the pile main body can be performed by welding, bolting, or the like. The rotating buried pile of the present invention thus configured cuts the pile main body to a desired length according to the depth of the supporting ground and the required length, and connects the tip member to the cut end of the pile main body. It is possible to easily manufacture a rotating buried pile set to a desired length while being fixed. Further, since the welding surface for connecting and fixing the tip member and the pile main body is one round along a horizontal plane orthogonal to the axis of the pile main body, welding can be easily performed.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a rotary buried pile according to the present invention will be described in detail with reference to the drawings. 1A is a perspective view of a main part of the rotary buried pile according to this embodiment in an exploded state, FIG. 1B is a front view of a main part of the rotary buried pile in a connected state, and FIG. (B) is a bottom view of (a), (c) is a sectional view taken along line AA of (b), and FIG. 3 is a perspective view of the tip member viewed from below. It is.
[0016]
In FIGS. 1 to 3, the rotary buried pile 1 is composed of an upper pipe-shaped pile main body 10 formed of a steel pipe, and a tip member 20 connected and fixed to a lower portion of the pile main body 10 by welding or the like. The tip member 20 can be connected and fixed to the lower end of the pile body 10 having a length, that is, to the tip of the rotary buried pile 1 that penetrates into the ground, to obtain the rotary buried pile 1 having a desired length.
[0017]
The outer diameter of the pile body 10 is set according to the required ground support force. For example, the outer diameter is set in a range of about 100 to 300 mm, and the thickness is set in a range of about 4 to 8 mm. The lower end of the pile main body 10 is cut along a plane orthogonal to the axis, and is formed by cutting the pipe material in a direction orthogonal to the axial direction. For this reason, the lower end surface 11 does not require special processing, and the processing is completed simply by cutting, and can be easily cut to a desired length. The upper surface 12 of the pile body 10 is formed as a flat surface. Although not shown in the vicinity of the upper surface 12, a plurality of projections may be formed to give a rotational force when the rotary buried pile 1 is screwed into the ground and buried. May be provided. The pile body 10 is preferably formed from a steel pipe such as carbon steel for general structure.
[0018]
The tip member 20 connected to the lower end of the pile body 10 is also referred to as a shoe, and includes a cylindrical central body 21 and two inclined plate portions 22 formed on the outer peripheral surface of the central body. In this embodiment, they are integrally formed by casting. A horizontal disk portion 23 is formed at the lower end opening of the central body portion 21 and closed, and a cross-shaped tip projection 24 is provided on the horizontal plane at the lower end when viewed from the bottom. A step 25 into which the lower end of the pile main body 10 is inserted is formed on the inner periphery of the center trunk 21 on the opening side (upper side). The step portion 25 is formed to be thin and has an inner diameter slightly larger than the outer diameter of the pile body 10 so that the pile body 10 can be easily inserted. Four slits 26 are formed in the outer peripheral wall surface of the step portion 25 in the vertical direction, that is, in the axial direction. The disk portion 23 may have a through hole so as not to close the lower end opening.
[0019]
The two inclined plate portions 22, 22 have substantially the same shape, and each have a semicircular shape in plan view, as shown in FIG. The inclined plate portion 22 is such that, when the rotary buried pile 1 is rotated, for example, clockwise (clockwise), the rotary buried pile 1 penetrates into the ground and the rotary buried pile 1 enters the ground. The slope is rising. The outer diameter of the inclined plate portion 22 is set to about twice the outer diameter of the central body portion 21, the thickness is set to about 10 to 25 mm, and the thickness is preferably about 15 to 20 mm.
[0020]
Since the two inclined plate portions 22 and 22 are both formed to rise counterclockwise when viewed from above, each of the two inclined plate portions 22 is approximately 15 degrees from a horizontal plane in a front view of FIG. The shapes are inclined and cross each other at about 30 degrees. The inclined plate portions 22, 22 are not formed in a spiral shape, but project from the central body portion 21 in a state where a flat plate is inclined. Since the inclined plate portions 22 do not have a twisted shape like a spiral shape, they can be easily formed. Also, when casting, the shape is simple, and the mold can be easily formed.
[0021]
The front end projection 24 at the lower end has a thickness of about 30 mm, and when viewed from the front, the lower end has a shape in which an arc-shaped plate intersects at 90 degrees, and is easy to match with a cross-shaped mark formed on the ground and indicating an embedding position. It has become. When the rotary buried pile 1 is buried, when the pile 1 is erected on the surface of the ground, the tip protrusion 24 is shaped to pierce the ground. Note that the distal end portion is not formed by crossing arc-shaped plate members at the lower end, but is formed by crossing triangular plate members having inclined sides as shown in a distal end member 20A shown in FIG. There may be.
[0022]
The rotary buried pile 1 has the lower end of the pile main body 10 of an arbitrary length inserted inside the step 25 of the central body 21 of the tip member 20, and the lower end surface 11 is in contact with the lower end surface of the step 25. And the entire periphery of the fitted outer peripheral portion is welded and connected and fixed at a welded portion 27. Further, by welding the tip member 20 and the pile main body 10 along the slit 26 as necessary, it is joined along the circumferential direction and the axial direction, so that the welding strength can be improved. Note that the connection and fixation between the tip member 20 and the pile body 10 is not limited to welding, but a hole (not shown) that connects the pile body 10 and the tip member 20 is formed, and a bolt or a pin is inserted through this hole. It may be fixed.
[0023]
The burying operation of the rotary buried pile according to the present embodiment configured as described above will be described below. When the rotary buried pile 1 is buried, the rotary buried pile 1 is erected on the ground using a piling machine (not shown), and a driving device for rotating and pushing is mounted on the head thereof, and the rotary buried pile is driven by the drive. Push 1 into the ground while rotating as if screwing. When standing upright on the ground, the rotary buried pile 1 can be accurately positioned at the buried position by aligning the cross-shaped tip projection 24 at the lower end of the tip member 20 with a mark (not shown) on the ground surface or the like. it can.
[0024]
When the rotary buried pile 1 is set up vertically by the driving device, the tip projection 24 pierces the ground surface. When a clockwise rotational force is applied to the rotary buried pile 1 and pressed in this state, the tip of the rotary buried pile 1 does not swing, and the inclined plate portions 22 and 22 of the tip member 20 connected to the tip are placed in the ground. Cut into the ground. When entering the ground, the earth and sand below the tip protrusion 24 is excavated and softened and removed to the outer peripheral side, and is compressed to the outer peripheral surface side of the center trunk 21. Then, since the inclined plate portions 22 cut into the compressed earth and sand, the inclined plate portion 22 is located in the compressed earth and sand to increase the supporting force.
[0025]
Since the rotating buried pile 1 is rotated in a pressed state, the inclined plate portions 22 and 22 are screwed into the ground, so that the generation of vibration and noise can be suppressed to a small extent, and the excavation and softening of the earth and sand by the tip protrusion 24 can be performed. Thus, the penetration resistance can be reduced. Further, since no waste soil is generated at the time of burial, the waste soil treatment can be omitted and the construction can be facilitated. After being buried, the rotary buried pile 1 is supported in the ground by the inclined plate portions 22, 22 having an outer diameter larger than the diameter of the pile main body 10, so that the supporting force when the pile main body 10 is used alone is large. Supporting force can be obtained. Moreover, since the rotary buried pile 1 does not loosen the ground when buried, the supporting force can be exerted in a form that makes full use of the ground force.
[0026]
In the above-described embodiment, the example in which the pile main body is inserted inside the distal end member and connected and fixed is shown, but the pile main body 10 and the distal end member 20 can be connected as shown in FIG. In the case of the rotary buried pile 1A in FIG. 5A, the diameter of the cylindrical central trunk portion 21 of the tip member 20 and the outer diameter of the pile main body 10A are set to be equal, and the two are abutted and connected and fixed by, for example, welding. Is done. In the case of the rotary buried pile 1B shown in FIG. 5B, the inside diameter of the pile main body 10B is fitted around the outer periphery of the cylindrical central body 21 of the tip member 20 by welding or the like in a state where the pile body 10B is fitted in a predetermined range. Connected and fixed. Although not shown, when the pile main body is externally fitted to the outer periphery of the tip member, a step portion may be provided on the outer periphery of the central trunk portion so as to be externally fitted. In addition, since the steel pipe which comprises a pile main body is based on an outer diameter generally, it is preferable that the pile main body 10 is inserted in the center trunk | drum 21 of the front-end | tip member 20 as shown in FIG. Further, in the example of FIG. 5, an example in which the central body portion has no slit is shown, but a slit may be provided and a step portion is formed, but the step portion is not necessarily required.
[0027]
Further, in the above embodiment, the inclined plate portion 22 formed on the outer periphery of the cylindrical central body portion 21 of the distal end member 20 is constituted by a flat plate in an inclined state. However, as shown in FIG. It may be formed of the plate 22A. When the inclined plate portion is constituted by the spiral plate 22A as described above, the spiral plate protrudes horizontally from the center trunk portion in the radial direction, so that the ground support force can be increased. A disk portion 23A is welded to the lower end opening of the tip member 20A by welding, and a small-diameter opening 23a is formed at the center of the disk portion. A substantially trapezoidal tip projection 24A protrudes from the lower surface of the disk portion. This tip protrusion can pierce the ground first when burying the rotary buried pile connected with this tip member in the ground, and can prevent the lower end from swinging when applying rotation to the pile and excavate and soften the earth and sand. It can be buried stably.
[0028]
Next, another embodiment of the present invention will be described in detail with reference to FIGS. FIG. 7 is a perspective view of another embodiment of the tip member according to the present invention, and a front view of a main part showing a positional relationship between the tip member and the pile body. FIG. 8 shows a state where the pile body and the tip member are connected and fixed. It is principal part sectional drawing. Note that this embodiment is characterized in that the lower end of the center trunk is open compared to the above-described embodiment. The same reference numerals are given to other substantially equivalent components, and detailed description will be omitted.
[0029]
7 and 8, the tip member 20B is connected and fixed to the tip of the rotary buried pile which penetrates into the ground, and protrudes from the cylindrical central body 21B and the outer peripheral surface of the central body. The inclined plate portions 22 and 22 to be provided are integrally formed by casting, and the central body portion 21B has a cylindrical shape with an open lower part, and the lower end of the central body portion is chamfered and sharply pointed. The details are 21b.
[0030]
A step portion 25 is formed in the upper part of the central trunk portion 21B, and the pile main body 10 can be inserted. The step portion 25 has no slit. In order to connect and fix the tip member 20B to the pipe-shaped pile body 10 to form the rotary buried pile 1C, the lower end surface 11 of the pile body 10 is inserted into the step portion 25 and the upper end of the tip member 20B and the pile body 10 are The outer periphery and the outer periphery are joined and fixed by a welded portion 27 welded over the entire horizontal periphery. In this embodiment, the outer peripheral edge of the inclined plate portion 22 is rounded, so that the earth and sand can easily escape to the outer periphery of the inclined plate portion 22 at the time of penetration, thereby reducing the resistance of the earth and sand.
[0031]
Also in this embodiment, the tip member 20B is small in size and easy to manufacture, and the rotary buried pile 1C is connected to the lower end of the pile body 10 having a desired length by connecting and fixing the tip member 20B so that the rotation of the desired length can be achieved. The buried pile 1C can be easily manufactured. In addition, the burial can be buried with little penetration resistance into the ground and little noise or vibration. In particular, in this embodiment, since the earth and sand enter the inside of the center trunk portion 21B at the time of penetration, the penetration resistance can be reduced as compared with the above embodiment.
[0032]
Further, another embodiment of the present invention will be described in detail with reference to FIG. This embodiment is different from the above-described embodiment in that the tip member has three inclined plate portions formed in the central body portion and is integrally formed by welding or the like to the central body portion. It is a feature.
[0033]
In FIG. 9, the distal end member 30 includes a cylindrical central body 31 formed of a steel plate, and three inclined plate parts 32 formed on the outer peripheral surface of the central body. Each has an opening angle of 120 degrees, and is welded to the central body 31 by welding in the present embodiment. A circular plate portion 33 made of a circular steel plate having a center hole 33a is welded to the opening at the lower end. A distal end projection 34 is provided below the disk portion 33, and has a central flat portion and inclined portions on both sides thereof. The tip protruding portion 34 prevents the swinging of the pile when it is buried by piercing the ground surface when burying the rotary buried pile to which the tip member 30 is fixed, and also excavates and softens the earth and sand.
[0034]
The tip member 30 shown in the embodiment of FIG. 9 is also easy to manufacture similarly to the above-described embodiments, and the tip member 30 is connected to and fixed to the pipe-shaped pile body 10 by welding or the like, so that the desired length can be easily obtained. Can be manufactured. Rotary buried piles manufactured in this way do not generate waste soil when buried, have low vibration and can be buried with minimal noise to nearby areas. The distal end member 30 may also be formed by casting to form the central body portion 31, the inclined plate portion 32, the disk portion 33, and the distal end projection 34 integrally.
[0035]
As described above, one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention described in the appended claims. Design changes can be made. For example, an example has been described in which two or three inclined plate portions are provided, but it is needless to say that one or more than three inclined plate portions may be provided. Further, the lower surface of the tip projection is formed by an arc portion or an inclined surface, but may be formed by a flat surface. The connection and fixation of the pile main body and the tip member are not limited to welding, and the pile body may be inserted into the step portion of the tip member and the overlapped portion may be fixed by, for example, bolting.
[0036]
The tip member only has to have a center trunk portion and an inclined plate portion projecting from the outer peripheral surface thereof, and may have a tip end opened. In this case, when buried in the ground, the earth and sand flows into the pipe-shaped pile main body from the lower end opening of the tip member, so that the penetration resistance can be reduced. In addition, instead of a disk closing the lower end of the central trunk, if it is closed with a core that tapers downward in the shape of an inverted cone, earth and sand can be easily distributed to the left and right when penetrating, reducing penetration resistance. it can.
[0037]
【The invention's effect】
As can be understood from the above description, the tip member of the rotary buried pile according to the present invention is small and can be easily manufactured, and is easily connected and fixed to the pipe-shaped pile body to have an arbitrary length. Rotary buried piles can be manufactured. The rotary buried pile according to the present invention has a configuration in which the pile main body and the tip member are connected and fixed, the rotary buried pile having a desired length can be easily manufactured, and the tip is attached to the pile main body cut in accordance with the depth of the supporting ground. Since the members are fixed, a waste portion of the pile main body can be eliminated. In addition, it can be buried in the ground with low penetration resistance, and the generation of vibration and noise can be suppressed.
[Brief description of the drawings]
FIG. 1A is a perspective view of an essential part showing an exploded state of an embodiment of a rotary buried pile according to the present invention, and FIG. 1B is a front view of a main part of the rotary buried pile in a connected state.
2A is a front view of the distal end member of FIG. 1, FIG. 2B is a bottom view of FIG. 1A, and FIG. 2C is a cross-sectional view taken along line AA of FIG.
FIG. 3 is a perspective view of the distal end member of FIG. 2 as viewed from below.
FIG. 4 is a perspective view of another embodiment of the tip member viewed from below.
5A is a schematic perspective view of a rotary buried pile in which a cylindrical portion of a tip member and a pile main body are abutted and connected and fixed, and FIG. 5B is a perspective view of the pile body externally fitted and connected to the cylindrical portion of the tip member. The schematic perspective view of the rotating buried pile fixed.
6A is a front view of a tip member having an inclined plate portion formed in a spiral shape, FIG. 6B is a bottom view thereof, and FIG. 6C is a sectional view taken along line BB of FIG.
7A is a perspective view of still another embodiment of the tip member, and FIG. 7B is a front view of a main part showing a positional relationship between the tip member and the pile main body of FIG.
8 is a cross-sectional view of a main part in a state where the tip member and the pile main body in FIG. 7 are connected and fixed.
9A and 9B show an embodiment of a tip member having three inclined plate portions, wherein FIG. 9A is a front view, FIG. 9B is a bottom view thereof, and FIG. 9C is a cross-sectional view taken along line CC of FIG.
[Explanation of symbols]
1, 1A, 1B, 1C ... rotary buried pile, 10, 10A, 10B ... pile body, 20, 20A, 20B, 30 ... tip member, 21, 21B, 31 ... central trunk, 22, 22A, 32 ... inclined plate Part, 23, 23A, 33: disk part, 24, 24A, 34: tip protrusion, 25: step part, 27: welded part
