JP2004131923A - Extracting method for existing underground structure - Google Patents

Extracting method for existing underground structure Download PDF

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JP2004131923A
JP2004131923A JP2002262284A JP2002262284A JP2004131923A JP 2004131923 A JP2004131923 A JP 2004131923A JP 2002262284 A JP2002262284 A JP 2002262284A JP 2002262284 A JP2002262284 A JP 2002262284A JP 2004131923 A JP2004131923 A JP 2004131923A
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Japan
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existing
casing
lowermost
ground
water
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JP2002262284A
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JP3500387B1 (en
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Akio Kamishima
神島 昭男
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Kamishimagumi:Kk
株式会社神島組
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Priority to JP2002237561 priority
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an extracting method for extracting an existing structure from a ground with excellent construction efficiency and at a low cost. <P>SOLUTION: A casing 2 is rotatingly propelled against the ground 5. When the lowermost end of the casing 2 reaches a depth deeper than the lowermost end of the existing structure 3, the rotating propulsion of the casing 2 is stopped. A cutting hole 7 extending from the uppermost end to the lowermost end of the existing structure 3 is formed in the existing structure 3 so as to pass the center axis of the exiting structure 3. After a jet pump 9 is connected to the uppermost end of the cutting hole 7, high-pressure water is fed from the jet pump 9 toward the cutting hole 7. By this, water is fed into the casing 2, and the existing structure 3 is suspended in an immersed state in the casing. A buoyancy acts on the existing structure 3. With the buoyancy acting on the existing structure 3, the existing structure 3 is lifted and extracted from the ground 5. <P>COPYRIGHT: (C)2004,JPO

Description

【0001】
【発明の属する技術分野】
この発明は、地中の埋設された既設構造物を地盤から引き抜く引抜工法に関するものである。
【0002】
【従来の技術】
各種建造物の建築、構築を行う場合には地盤整備を行う必要がある。その一環として、コンクリート杭などのコンクリート構造物、鋼製杭などの鋼製構造物、木製杭などの木製構造物、その他の地中深く埋設されたまた残存している構造物(以下、これらの構造物を総称して「既設構造物」という)を引き抜く引抜作業が実行される。従来、この引抜作業は次のようにして行っていた。まず、既設構造物を包むようにケーシング(鋼管)を差し込み、ケーシングと既設構造物との間の土砂を除去する。そして、既設構造物をクレーン等の重機機械で吊上げて既設構造物の引き抜きを実行していた。
【0003】
【発明が解決しようとする課題】
しかしながら、従来工法では、重機機械の吊上げ力のみを利用して既設構造物の引抜を実行しているため、既設構造物の大型化に伴い、重機機械に要求される吊上能力も高くなり、大型の重機機械が必要となる。その結果、施工効率や施工コストの面で改善の余地が大きく残されていた。
【0004】
この発明は上記課題に鑑みなされたものであり、優れた施工効率で、しかも低コストで地盤から既設構造物を引き抜く引抜工法を提供することを目的とする。
【0005】
【課題を解決するための手段】
この発明は、地中の埋設された既設構造物を引き抜く引抜工法であって、上記目的を達成するため、既設構造物の最下端に繋がる削孔を既設構造物に形成する第1工程と、削孔を介して既設構造物の最下端に向けて水を送給して既設構造物に対して浮力を与える第2工程と、既設構造物に対して浮力を与えた状態のまま既設構造物を吊り上げる第3工程とを備えている。
【0006】
このように構成された発明では、既設構造物の最下端に繋がる削孔を既設構造物に形成した後、その削孔を介して既設構造物の最下端に向けて水を送給する。これによって、既設構造物の最下端から吐出される水の一部が既設構造物の外周側面に沿って地盤表面側に流れ、その水の存在により既設構造物に対して浮力が作用する。そして、この浮力が作用する状態で既設構造物を吊り上げて地盤から既設構造物を引き抜く。このように浮力を利用することで既設構造物の引抜に必要な吊上げ力を低減することが可能となる。
【0007】
ここで、既設構造物の最下端に向けて水を送給する前に、予め既設構造物を囲むようにケーシングを地盤に回転推進してケーシングの先端部を既設構造物の最下端以上の深さに到達させるように構成してもよい。この場合、既設構造物の最下端に向けて水を送給すると、既設構造物の最下端の下方に位置する地盤(土砂など)が給水により押し流されるとともに、ケーシング内が水で満たされる。つまり、既設構造物が貯水されたケーシング内に存在することとなり、既設構造物に対して浮力が作用する。このように、既設構造物の最下端から吐出される水が効率良くケーシング内を流れ、少ない水量で既設構造物の対して浮力を確実に与えることができる。
【0008】
また、第2工程前に、複数の鋼片を既設構造物の最下端の下方に位置させると、既設構造物の最下端から吐出される水が地盤に浸み込むのを効果的に防止し、水の利用効率をさらに高めることができる。また、複数の鋼片を用いることなく、施工効率を高めるために給水時の水圧を高めた場合、既設構造物の最下端の下方に位置する地盤をさらに深く掘り下げてしまうが、上記のように複数の鋼片を設けることで圧送されてきた水による地盤の掘り下げを防止することができる。
【0009】
さらに、地盤表面の上方位置で既設構造物に補助部材を取り付け、既設構造物の引抜の際(第3工程)に、既設構造物の引抜方向とほぼ平行な方向に補助部材を押し上げるように構成すれば、その押上力が既設構造物の引抜力となり、吊上げ力をさらに低減することができる。
【0010】
【発明の実施の形態】
図1および図2は、この発明にかかる地中既設構造物の引抜工法の一実施形態を示す図である。この引抜工法では、図1(a)に示すように、大径管の下端円周に削孔用チップ1を備えたケーシング2が既設構造物3の周面を取り囲むようにケーシング2を地盤表面に設置した後、駆動機構4を作動させることでケーシング2を地盤5に対して回転推進してその全長に亙り削孔して、既設構造物3と地盤5の縁を切っていく。なお、この実施形態では、内面チップ(図示省略)をケーシング2の内面の該ケーシング2の内径よりも設定寸法小径の想定円周線上に設けることでケーシング2内周面と既設構造物3との間に設定寸法のギャップ6を形成している。
【0011】
そして、同図(b)に示すように、ケーシング2の最下端、つまり削孔用チップ1が既設構造物3の最下端以上の深さに到達すると、ケーシング2の回転推進を停止する。そして、既設構造物3の中心軸を通過するように既設構造物3の最上端から最下端に繋がる削孔7を既設構造物3に形成する。なお、ここでは、削孔7を中心軸に沿って形成しているが、その中心軸からずれて削孔7を形成してもよく、また既設構造物3の側面から最下端に繋がるように削孔7を形成するようにしてもよい。この点に関しては、後の実施形態においても全く同様である。なお、同図中の符号8はワイヤであり、既設構造物3の上部に取り付けられ、クレーン等の重機機械により既設構造物3を吊上げ可能となっている。
【0012】
次に、図2(a)に示すように、ジェットポンプ9および一時回収タンク10をそれぞれ削孔7およびケーシング2に配管接続する。すなわち、上記のようにして形成された削孔7の最上端に対して給水用配管の一方端を接続するとともに、その給水用配管の他方端をジェットポンプ9の吐出口と接続する。また、ケーシング2の上端側でケーシング2の中空空間に排水用配管の一方端を連通接続するとともに、その排水用配管の他方端を一時回収タンク10に接続する。
【0013】
各配管接続が完了すると、ジェットポンプ9を作動させてジェットポンプ9から高圧水を削孔7に向けて給水する。すると、この高圧水は削孔7を介して既設構造物3の最下端に向けて圧送され、この最下端から吐出された水は、その最下端と接する地盤の土砂5a(図1(b))をギャップ6側に押し流す。そして、水を連続的に給水し続けると、該ギャップ6にも給水されてケーシング2の内部に水が溜まるとともに、オーバーフローする水については排水用配管を介して一時回収タンク10に回収される。なお、回収された土砂を含む水については、そのまま放流したり、土砂を分離した後で放流することができる。もちろん、水については必要に応じて循環的に利用するようにしてもよい。
【0014】
このようにケーシング2内に水を供給することでケーシング2内で既設構造物3が浸水状態で吊持された状態となり、その既設構造物3に対して浮力が作用する。そして、図2(b)に示すように、この浮力を受けた状態のままクレーンなどの重機機械をオペレータが操作してワイヤ8により既設構造物3を上方向(引抜方向)に吊上げ、地盤5から引き抜く。このとき、ジェットポンプ9から水を連続的に供給し続けるのが望ましいが、引抜途中で給水を停止するようにしてもよい。
【0015】
そして、引抜が完了すると、ジェットポンプ9を完全に停止させた後、既設構造物3を引き抜いた跡孔を貧配合モルタル、土、砂などで埋め戻した後、ケーシングをクレーンやワイヤ等で地上に引き抜き、工事を完了する。
【0016】
以上のように、この実施形態では、既設構造物3の最下端に繋がる削孔7を既設構造物3に形成した後、その削孔7を介して既設構造物3の最下端に向けて水を送給してケーシング2内を水で満たす。これによって、既設構造物は地盤5から完全に切り離され、しかもケーシング2内で浸水状態で存在している。したがって、既設構造物3に対して浮力が作用することとなり、既設構造物3を吊り上げて地盤から既設構造物3を引き抜く際に、その浮力分だけ既設構造物3の引抜に必要な吊上げ力を低減させることが可能となる。その結果、従来工法で使用していた重機機械に比べて吊上能力の低い重機機械を用いて既設構造物を引き抜くことができるようになり、施工効率を向上させるとともに、施工コストを抑制することができる。
【0017】
また、既設構造物3はその側面だけではなく、その最下端面も地盤5と縁が切れた状態で引き抜かれるため、効率的な引抜作業を行うことができる。
【0018】
また、既設構造物3の最下端から吐出される水はケーシング2内に導かれ、ギャップ6に沿って地盤表面側に流れるため、既設構造物の最下端から吐出される水が効率良くケーシング内に流れ、既設構造物3の対して浮力を確実に与えることができる。
【0019】
なお、本発明は上記した実施形態に限定されるものではなく、その趣旨を逸脱しない限りにおいて上述したもの以外に種々の変更を行うことが可能である。例えば、上記実施形態では、浮力と吊上げ力とを用いて既設構造物3を引き抜いているが、さらに図3に示すように、油圧シリンダなどのアクチュエータによる押上力を付加させることで吊上げ力をさらに低減させることができる。
【0020】
図3は、この発明にかかる地中既設構造物の引抜工法の他の実施形態を示す図である。この引抜工法では、既設構造物3の上端部に鋼管11の下端部を連結する。例えば既設構造物3がコンクリート製である場合には既設構造物3中に杭補強筋が設けられているため、その杭補強筋と鋼管11とを溶接により連結する。また、既設構造物3が鋼製杭である場合には杭本体を鋼管11と直接溶接して連結する。そして、鋼管11の上端部に引抜方向(同図の上下方向)とほぼ直交する方向に鋼製梁部材12を溶接などの連結方法により連結する。これにより、地盤表面の上方位置で鋼管11および鋼製梁部材12よりなる補助部材が既設構造物3に取り付けられる。
【0021】
そして、ケーシング2の上端部と梁部材12との間に油圧ジャッキなどのアクチュエータ13が複数本配置されており、それらのアクチュエータ13を作動させることで既設構造物の引抜方向(上方向)とほぼ平行な方向に補助部材(鋼管11および鋼製梁部材12)を押し上げ、その結果、既設構造物3に対して引抜方向への押上力を加えることが可能となっている。したがって、クレーンなどの重機機械を操作してワイヤ8により既設構造物3を吊上げ、地盤5から引き抜く際、それと同時にアクチュエータ13のロッド13aを伸張させることで、その押上力分だけ既設構造物3の引抜に必要な吊上げ力を低減させることが可能となる。したがって、さらに一段と低い吊上げ能力の重機機械を用いて既設構造物の引抜が可能となり、施工効率を向上させるとともに、施工コストを抑制することができる。なお、油圧シリンダなどのアクチュエータ13の本数や配設位置については特に限定されるものではない。
【0022】
また、上記実施形態では、ケーシング2を所定深さまで回転推進させた後、そのままの状態で削孔7を介して水を給水して既設構造物3の最下端から水を吐出しているが、図4に示すように、複数の鋼片21を既設構造物3の最下端の下方に位置させるようにしてもよく、こうすることで次のような作用効果が得られる。
【0023】
図4は、この発明にかかる地中既設構造物の引抜工法の別の実施形態を示す図である。この実施形態では、同図に示すように、ケーシング2内周面と既設構造物3との間のギャップ6に2つの鋼片21が回動軸22回りに回動自在に軸支されている。各鋼片21は略スコップ形状を有しており、ケーシング2の下端近傍に配置された状態で油圧シリンダのロッド23を伸張させると、回動軸22回りにそれぞれ相反する方向に回動して既設構造物3の最下端の下方に位置し、既設構造物3の最下端面を覆うこととなる(同図(b))。この状態でジェットポンプ9を作動させてジェットポンプ9から高圧水を削孔7に向けて給水すると、既設構造物3の最下端から高圧水が吐出されるが、その高圧水の大部分は複数の鋼片21によりギャップ6側に導かれる。このため、給水が地盤5に浸み込むのを効果的に防止し、水の効率的な利用を図ることができる。
【0024】
また、上記実施形態ではジェットポンプ9から高圧水を給水する、つまり施工効率を高めるために給水時の水圧を高めているが、図1ないし図3に示すように削孔7から高圧水を地盤の土砂5a(図1(b))に向けて吐出すると、単に土砂5aを押し流すのみならず、さらに地盤5をさらに深く掘り下げてしまうが、上記のように複数の鋼片21を設けることで圧送されてきた水による地盤5の掘り下げを防止することができる。したがって、作業効率の面でも有利なものとなる。
【0025】
また、上記実施形態では、既設構造物3を一度に地盤5から引き抜いているが、引抜方向(各図の上下方向)における既設構造物3の大きさによっては一度に地盤5から引き抜くのが困難な場合がある。その場合には、図5に示すように適当な位置まで引き抜いた後、既設構造物3を例えば仮想切断線(図5(a)中の1点鎖線)に沿って切断し、さらに上記実施形態と同様の引抜作業を繰り返すようにすればよい。このとき、切断された既設構造物3のうち上方部分についてはクレーンなどの重機機械で吊持されているが、切断とともに下方部分については吊持が解除されてケーシング2内に落下してしまう。そこで、このような問題に対応すべく、図5に示す実施形態では、たとえクレーンなどの重機機械により吊持されていなくとも既設構造物3がケーシング2内に落下するのを防止する落下防止機構を設けている。
【0026】
図5は、この発明にかかる地中既設構造物の引抜工法のさらに別の実施形態を示す図である。この実施形態では、ケーシング2の内壁面2aには、落下防止機構30が4個、しかも同図(b)に示すように平面視において等角度間隔で設けられている。なお、落下防止機構30の配設数については、これに限定されず、3個以上設けることで後述するようにして既設構造物3の落下を確実に防止することができる。
【0027】
各落下防止機構30は、同図(c)に示すように、ケーシング2の内周面に取り付けられる本体部31と、その本体部31に対して回動軸32回りに回動自在に軸支された可動部33と、可動部33が所定角度以上移動するのを阻止するストッパー34とを備えている。すなわち、各落下防止機構30では、可動部33の後端部がケーシング2の内壁面2aに対して回動軸32回りに0゜から約60゜の範囲で回動可能であり、その先端部は既設構造物3の側面3aと当接している。このため、ケーシング2が既設構造物3に対して相対的に下方移動する際には可動部33はフリーに回動自在となっており、上記相対移動は自由となっている。逆に既設構造物3がケーシング2に対して相対的に下方移動する際には可動部33が約60゜まで回動する間については上記相対移動が可能となるが、それ以上移動しようとすると、可動部33の後端部がストッパー34に係止され、可動部33によりケーシング2に対する既設構造物3の下方移動が阻止される。こうして既設構造物3の落下を効果的に防止することができ、既設構造物3を複数回に分けて引き抜くことが可能となる。したがって、この実施形態によれば、引抜方向における既設構造物3の大きさに制限されず、既設構造物3を確実に引き抜くことが可能となる。
【0028】
また、上記実施形態では、ケーシング2の回転推進後に削孔7を形成しているが、削孔形成後にケーシングの回転推進を実行したり、ケーシングの回転推進と同時に削孔7を形成するようにしてもよいことはいうまでもない。
【0029】
さらに、上記実施形態では、ケーシング2を所定深さまで回転推進させた後、削孔7を介して水を給水して既設構造物3の最下端から水を吐出しているが、図6に示すようにケーシング2を用いず、削孔7を介して既設構造物3の最下端から水を吐出させるようにしてもよい。
【0030】
図6は、この発明にかかる地中既設構造物の引抜工法のさらに他の実施形態を示す図である。この実施形態では、同図(a)に示すように、既設構造物3の中心軸を通過するように既設構造物3の最上端から最下端に繋がる削孔7を既設構造物3に形成する。そして、ジェットポンプ9を削孔7に配管接続した後、ジェットポンプ9を作動させてジェットポンプ9から高圧水を削孔7に向けて給水する。すると、この高圧水は削孔7を介して既設構造物3の最下端に向けて圧送され、この最下端から吐出された水の一部は、同図中の矢印に示すように、既設構造物3の外周側面に沿って地盤表面に流れ、その水によって既設構造物3に対して浮力が作用する。
【0031】
次に、同図(b)に示すように、この浮力を受けた状態のままクレーンなどの重機機械をオペレータが操作してワイヤ8により既設構造物3を上方向(引抜方向)に吊上げ、地盤5から引き抜く。このとき、ジェットポンプ9から水を連続的に供給し続けるのが望ましいが、引抜途中で給水を停止するようにしてもよい。
【0032】
そして、引抜が完了すると、ジェットポンプ9を完全に停止させた後、既設構造物3を引き抜いた跡孔を貧配合モルタル、土、砂などで埋め戻す。
【0033】
以上のように、この実施形態においても、既設構造物3に対して浮力を作用ささせた状態で既設構造物3を吊り上げて地盤5から既設構造物3を引き抜くように構成しているので、その浮力分だけ既設構造物3の引抜に必要な吊上げ力を低減させることが可能となる。その結果、従来工法で使用していた重機機械に比べて吊上げ能力の低い重機機械を用いて既設構造物を引き抜くことができるようになり、施工効率を向上させるとともに、施工コストを抑制することができる。また、ケーシング2を用いていないので、作業工程を簡素化することができ、施工効率および施工コストの面でさらに有利なものとなる。
【0034】
【発明の効果】
以上のように、この発明によれば、既設構造物の最下端に繋がる削孔を既設構造物に形成した後、その削孔を介して既設構造物の最下端に向けて水を送給して既設構造物に対して浮力を作用させているので、従来工法よりも小さな吊上げ力で既設構造物の引抜が可能となる、つまり、より吊上げ能力の重機機械を用いて既設構造物の引抜が可能となり、施工効率を向上させるとともに、施工コストを抑制することができる。
【図面の簡単な説明】
【図1】この発明にかかる地中既設構造物の引抜工法の一実施形態を示す図である。
【図2】この発明にかかる地中既設構造物の引抜工法の一実施形態を示す図である。
【図3】この発明にかかる地中既設構造物の引抜工法の他の実施形態を示す図である。
【図4】この発明にかかる地中既設構造物の引抜工法の別の実施形態を示す図である。
【図5】この発明にかかる地中既設構造物の引抜工法のさらに別の実施形態を示す図である。
【図6】この発明にかかる地中既設構造物の引抜工法のさらに他の実施形態を示す図である。
【符号の説明】
2…ケーシング
3…既設構造物
5…地盤
7…削孔
11…鋼管(補助部材)
12…鋼製梁部材(補助部材)
21…鋼片
[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a drawing method for pulling an existing structure buried underground from the ground.
[0002]
[Prior art]
When building and constructing various structures, it is necessary to improve the ground. As part of this, concrete structures such as concrete piles, steel structures such as steel piles, wooden structures such as wooden piles, and other structures buried or remaining deep underground (hereinafter, these A pull-out operation is performed to pull out the structures (collectively, “existing structures”). Conventionally, this drawing operation has been performed as follows. First, a casing (steel pipe) is inserted so as to surround the existing structure, and soil and sand between the casing and the existing structure are removed. Then, the existing structure is lifted by a heavy machine such as a crane to pull out the existing structure.
[0003]
[Problems to be solved by the invention]
However, in the conventional method, since the existing structure is pulled out using only the lifting force of the heavy machinery, the lifting capacity required for the heavy machinery also increases with the enlargement of the existing structure, Large heavy machinery is required. As a result, there is much room for improvement in terms of construction efficiency and construction cost.
[0004]
The present invention has been made in view of the above problems, and has as its object to provide a drawing method for pulling out an existing structure from the ground with excellent construction efficiency and at low cost.
[0005]
[Means for Solving the Problems]
The present invention is a drawing method for pulling out an existing structure buried underground, in order to achieve the above object, a first step of forming a hole in the existing structure that is connected to the lowermost end of the existing structure, A second step of supplying water to the lowermost end of the existing structure through a borehole to give buoyancy to the existing structure, and a step of providing buoyancy to the existing structure while maintaining the existing structure with buoyancy And a third step of lifting
[0006]
In the invention configured as described above, after a drilling hole connected to the lowermost end of the existing structure is formed in the existing structure, water is supplied to the lowermost end of the existing structure through the drilling. As a result, part of the water discharged from the lowermost end of the existing structure flows to the ground surface side along the outer peripheral side surface of the existing structure, and buoyancy acts on the existing structure due to the presence of the water. Then, the existing structure is lifted in a state where the buoyancy acts, and the existing structure is pulled out from the ground. By using the buoyancy in this way, it is possible to reduce the lifting force required for pulling out the existing structure.
[0007]
Here, before water is supplied toward the lowermost end of the existing structure, the casing is previously rotationally propelled to the ground so as to surround the existing structure, and the front end of the casing is set to a depth equal to or more than the lowermost end of the existing structure. It may be configured to reach the height. In this case, when water is supplied toward the lowermost end of the existing structure, the ground (such as earth and sand) located below the lowermost end of the existing structure is flushed by the water supply, and the inside of the casing is filled with water. That is, the existing structure exists in the casing in which the water is stored, and buoyancy acts on the existing structure. In this way, water discharged from the lowermost end of the existing structure efficiently flows through the casing, and buoyancy can be reliably given to the existing structure with a small amount of water.
[0008]
Further, when the plurality of steel pieces are positioned below the lowermost end of the existing structure before the second step, water discharged from the lowermost end of the existing structure is effectively prevented from permeating into the ground. In addition, the water use efficiency can be further improved. Also, without using a plurality of steel slabs, if the water pressure at the time of water supply is increased in order to increase construction efficiency, the ground located below the lowermost end of the existing structure will be dug deeper, as described above. By providing a plurality of steel slabs, it is possible to prevent the ground from being dug down by the water that has been pumped.
[0009]
Further, an auxiliary member is attached to the existing structure at a position above the ground surface, and when the existing structure is pulled out (third step), the auxiliary member is pushed up in a direction substantially parallel to the drawing direction of the existing structure. Then, the lifting force becomes the pulling force of the existing structure, and the lifting force can be further reduced.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 and FIG. 2 are views showing one embodiment of a method of drawing an existing underground structure according to the present invention. In this drawing method, as shown in FIG. 1A, the casing 2 provided with a drilling tip 1 on the lower end circumference of a large diameter pipe surrounds the peripheral surface of the existing structure 3 so as to cover the ground surface. After that, the casing 2 is rotationally propelled with respect to the ground 5 by operating the drive mechanism 4 so as to drill holes over the entire length thereof, and cut off the edges of the existing structure 3 and the ground 5. In this embodiment, by providing the inner surface chip (not shown) on the inner circumferential surface of the casing 2 on an assumed circumferential line having a set diameter smaller than the inner diameter of the casing 2, the inner circumferential surface of the casing 2 and the existing structure 3 are connected. A gap 6 having a set dimension is formed therebetween.
[0011]
Then, as shown in FIG. 4B, when the drilling tip 1 reaches the lowermost end of the casing 2, that is, the depth of the drilling tip 1 is equal to or greater than the lowermost end of the existing structure 3, the rotational propulsion of the casing 2 is stopped. Then, a hole 7 is formed in the existing structure 3 so as to pass from the uppermost end to the lowermost end of the existing structure 3 so as to pass through the central axis of the existing structure 3. Here, the drilled holes 7 are formed along the central axis. However, the drilled holes 7 may be formed so as to be shifted from the central axis, and the drilled holes 7 are connected from the side surface of the existing structure 3 to the lowermost end. The hole 7 may be formed. This is exactly the same in the following embodiments. Reference numeral 8 in the figure denotes a wire, which is attached to the upper part of the existing structure 3 and can lift the existing structure 3 by a heavy machine such as a crane.
[0012]
Next, as shown in FIG. 2A, the jet pump 9 and the temporary recovery tank 10 are connected to the borehole 7 and the casing 2, respectively, by piping. That is, one end of the water supply pipe is connected to the uppermost end of the drilled hole 7 formed as described above, and the other end of the water supply pipe is connected to the discharge port of the jet pump 9. In addition, one end of the drainage pipe is connected to the hollow space of the casing 2 at the upper end side of the casing 2, and the other end of the drainage pipe is connected to the temporary recovery tank 10.
[0013]
When each pipe connection is completed, the jet pump 9 is operated to supply high-pressure water from the jet pump 9 toward the drilled holes 7. Then, the high-pressure water is pumped toward the lowermost end of the existing structure 3 through the drilled hole 7, and the water discharged from the lowermost end is the earth and sand 5a on the ground contacting the lowermost end (FIG. 1 (b)). ) To the gap 6 side. When the water is continuously supplied, the water is also supplied to the gap 6 and the water accumulates inside the casing 2, and the overflowing water is recovered in the temporary recovery tank 10 via a drain pipe. The water containing the collected earth and sand can be discharged as it is, or can be discharged after separating the earth and sand. Of course, water may be used cyclically as needed.
[0014]
By supplying water into the casing 2 in this manner, the existing structure 3 is suspended in the casing 2 in a flooded state, and buoyancy acts on the existing structure 3. Then, as shown in FIG. 2 (b), the existing structure 3 is lifted upward (withdrawal direction) by the wire 8 by the operator operating a heavy equipment such as a crane while receiving the buoyancy, and the ground 5 Pull out from. At this time, it is desirable that water be continuously supplied from the jet pump 9, but the water supply may be stopped during withdrawal.
[0015]
When the drawing is completed, the jet pump 9 is completely stopped, and the trace holes from which the existing structure 3 has been drawn are backfilled with poorly mixed mortar, soil, sand, etc., and then the casing is ground with a crane or wire. To complete the construction.
[0016]
As described above, in this embodiment, after the drilling hole 7 connected to the lowermost end of the existing structure 3 is formed in the existing structure 3, water is directed toward the lowermost end of the existing structure 3 through the drilling 7. To fill the casing 2 with water. As a result, the existing structure is completely separated from the ground 5 and is present in the casing 2 in a flooded state. Therefore, buoyancy acts on the existing structure 3, and when the existing structure 3 is lifted and the existing structure 3 is pulled out from the ground, the lifting force required for pulling out the existing structure 3 is increased by the buoyancy. It can be reduced. As a result, existing structures can be pulled out using heavy machinery with lower lifting capacity than heavy machinery used in the conventional method, improving construction efficiency and reducing construction costs. Can be.
[0017]
In addition, since the existing structure 3 is pulled out not only at the side surface but also at the lowermost end surface in a state where the edge is cut off from the ground 5, efficient pulling-out work can be performed.
[0018]
In addition, the water discharged from the lowermost end of the existing structure 3 is guided into the casing 2 and flows to the ground surface side along the gap 6, so that the water discharged from the lowermost end of the existing structure is efficiently in the casing. And the buoyancy can be reliably given to the existing structure 3.
[0019]
The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, in the above embodiment, the existing structure 3 is pulled out using the buoyancy and the lifting force. However, as shown in FIG. 3, the lifting force is further increased by adding a lifting force by an actuator such as a hydraulic cylinder. Can be reduced.
[0020]
FIG. 3 is a view showing another embodiment of the method of drawing an underground existing structure according to the present invention. In this drawing method, the lower end of the steel pipe 11 is connected to the upper end of the existing structure 3. For example, when the existing structure 3 is made of concrete, since the pile reinforcement is provided in the existing structure 3, the pile reinforcement and the steel pipe 11 are connected by welding. When the existing structure 3 is a steel pile, the pile main body is directly welded to the steel pipe 11 and connected. Then, the steel beam member 12 is connected to the upper end portion of the steel pipe 11 in a direction substantially perpendicular to the drawing direction (vertical direction in the drawing) by a connection method such as welding. Thus, the auxiliary member including the steel pipe 11 and the steel beam member 12 is attached to the existing structure 3 at a position above the ground surface.
[0021]
A plurality of actuators 13 such as hydraulic jacks are arranged between the upper end portion of the casing 2 and the beam member 12, and when these actuators 13 are actuated, the actuator 13 is substantially in the withdrawal direction (upward direction) of the existing structure. The auxiliary members (the steel pipe 11 and the steel beam member 12) are pushed up in parallel directions, and as a result, it is possible to apply a pushing-up force to the existing structure 3 in the pull-out direction. Therefore, when the existing structure 3 is lifted by the wire 8 by operating a heavy machinery such as a crane and pulled out from the ground 5, at the same time, the rod 13a of the actuator 13 is extended, so that the existing structure 3 is lifted by the pushing force. It is possible to reduce the lifting force required for pulling out. Therefore, it is possible to pull out the existing structure using a heavy machinery having a much lower lifting capacity, thereby improving construction efficiency and suppressing construction cost. The number of actuators 13 such as hydraulic cylinders and the arrangement position are not particularly limited.
[0022]
Further, in the above embodiment, after the casing 2 is rotationally propelled to a predetermined depth, water is supplied from the lowermost end of the existing structure 3 by supplying water through the drilled holes 7 as it is, As shown in FIG. 4, the plurality of steel pieces 21 may be positioned below the lowermost end of the existing structure 3, whereby the following operation and effect can be obtained.
[0023]
FIG. 4 is a diagram showing another embodiment of the method of drawing an underground existing structure according to the present invention. In this embodiment, as shown in the figure, two steel pieces 21 are pivotally supported around a rotation shaft 22 in a gap 6 between the inner peripheral surface of the casing 2 and the existing structure 3. . Each of the billets 21 has a substantially scoop shape, and when the rod 23 of the hydraulic cylinder is extended in a state where the rod 23 is disposed near the lower end of the casing 2, the billets 21 rotate in opposite directions around the rotation shaft 22. It is located below the lowermost end of the existing structure 3 and covers the lowermost end surface of the existing structure 3 (FIG. 2B). In this state, when the jet pump 9 is operated to supply high-pressure water from the jet pump 9 toward the drilling holes 7, high-pressure water is discharged from the lowermost end of the existing structure 3. Is led to the gap 6 side by the steel piece 21. For this reason, water supply can be effectively prevented from seeping into the ground 5, and efficient use of water can be achieved.
[0024]
Further, in the above embodiment, high-pressure water is supplied from the jet pump 9, that is, the water pressure at the time of water supply is increased in order to increase construction efficiency. However, as shown in FIGS. When it is discharged toward the earth and sand 5a (FIG. 1 (b)), not only does the earth and sand 5a flow away, but also the ground 5 is dug deeper. It is possible to prevent the ground 5 from being dug down by the water that has been removed. Therefore, it is advantageous in terms of work efficiency.
[0025]
Further, in the above embodiment, the existing structure 3 is pulled out from the ground 5 at a time, but it is difficult to pull out the existing structure 3 from the ground 5 at a time depending on the size of the existing structure 3 in the pulling-out direction (vertical direction in each drawing). It may be. In this case, after being pulled out to an appropriate position as shown in FIG. 5, the existing structure 3 is cut along, for example, a virtual cutting line (a dashed line in FIG. 5A), and What is necessary is just to repeat the pulling-out operation similar to. At this time, the upper part of the cut existing structure 3 is suspended by a heavy machine such as a crane, but the lower part is released from the suspension and falls into the casing 2 with the cutting. In order to cope with such a problem, in the embodiment shown in FIG. 5, a fall prevention mechanism for preventing the existing structure 3 from falling into the casing 2 even if it is not hung by a heavy machine such as a crane. Is provided.
[0026]
FIG. 5 is a view showing still another embodiment of the underground existing structure drawing method according to the present invention. In this embodiment, four fall prevention mechanisms 30 are provided on the inner wall surface 2a of the casing 2 at equal angular intervals in plan view as shown in FIG. The number of the drop prevention mechanisms 30 is not limited to this, and by providing three or more, the existing structure 3 can be reliably prevented from falling as described later.
[0027]
As shown in FIG. 1C, each of the fall prevention mechanisms 30 includes a main body 31 attached to the inner peripheral surface of the casing 2 and a pivotally supported pivotal movement about the rotation axis 32 with respect to the main body 31. And a stopper 34 for preventing the movable portion 33 from moving more than a predetermined angle. That is, in each of the fall prevention mechanisms 30, the rear end of the movable portion 33 is rotatable about the rotation axis 32 with respect to the inner wall surface 2a of the casing 2 in the range of 0 ° to about 60 °, Is in contact with the side surface 3a of the existing structure 3. Therefore, when the casing 2 moves downward relative to the existing structure 3, the movable part 33 is freely rotatable, and the relative movement is free. Conversely, when the existing structure 3 moves downward relative to the casing 2, the above-described relative movement is possible while the movable portion 33 rotates up to about 60 °. The rear end of the movable portion 33 is locked by the stopper 34, and the movable portion 33 prevents the existing structure 3 from moving downward with respect to the casing 2. In this way, the existing structure 3 can be effectively prevented from dropping, and the existing structure 3 can be pulled out a plurality of times. Therefore, according to this embodiment, it is possible to reliably pull out the existing structure 3 without being limited by the size of the existing structure 3 in the pull-out direction.
[0028]
Further, in the above-described embodiment, the drilled holes 7 are formed after the rotary propulsion of the casing 2. However, the rotary propulsion of the casing is performed after the drilling is formed. It goes without saying that this may be done.
[0029]
Furthermore, in the above embodiment, after the casing 2 is rotationally propelled to a predetermined depth, water is supplied through the drilled holes 7 to discharge water from the lowermost end of the existing structure 3, as shown in FIG. 6. Instead of using the casing 2, water may be discharged from the lowermost end of the existing structure 3 through the hole 7.
[0030]
FIG. 6 is a view showing still another embodiment of the underground existing structure drawing method according to the present invention. In this embodiment, as shown in FIG. 1A, a hole 7 is formed in the existing structure 3 so as to pass through the center axis of the existing structure 3 and connect from the uppermost end to the lowermost end of the existing structure 3. . Then, after connecting the jet pump 9 to the borehole 7 by piping, the jet pump 9 is operated to supply high-pressure water from the jet pump 9 toward the borehole 7. Then, this high-pressure water is pumped toward the lowermost end of the existing structure 3 through the drill hole 7, and a part of the water discharged from this lowermost end is, as shown by an arrow in FIG. The water flows on the ground surface along the outer peripheral side surface of the object 3, and buoyancy acts on the existing structure 3 by the water.
[0031]
Next, as shown in FIG. 2B, an operator operates a heavy equipment such as a crane while receiving the buoyancy to lift the existing structure 3 upward (withdrawing direction) with the wire 8 and to lift the ground. Pull out from 5. At this time, it is desirable that water be continuously supplied from the jet pump 9, but the water supply may be stopped during drawing.
[0032]
Then, when the drawing is completed, the jet pump 9 is completely stopped, and then the trace holes from which the existing structure 3 is drawn are backfilled with poorly-mixed mortar, soil, sand, or the like.
[0033]
As described above, also in this embodiment, since the existing structure 3 is lifted while the buoyancy is applied to the existing structure 3, the existing structure 3 is pulled out from the ground 5, The lifting force required to pull out the existing structure 3 can be reduced by the buoyancy. As a result, existing structures can be pulled out using heavy machinery with lower lifting capacity than heavy machinery used in the conventional method, improving construction efficiency and reducing construction costs. it can. In addition, since the casing 2 is not used, the work process can be simplified, which is more advantageous in terms of construction efficiency and construction cost.
[0034]
【The invention's effect】
As described above, according to the present invention, after forming a drilled hole connected to the lowermost end of the existing structure in the existing structure, water is supplied to the lowermost end of the existing structure through the drilled hole. As the buoyancy acts on the existing structure, it is possible to pull out the existing structure with a smaller lifting force than the conventional method.In other words, it is possible to pull out the existing structure using a heavy machinery machine with a higher lifting capacity. This makes it possible to improve construction efficiency and reduce construction costs.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of a method for drawing an underground existing structure according to the present invention.
FIG. 2 is a view showing an embodiment of a method for drawing an underground existing structure according to the present invention.
FIG. 3 is a view showing another embodiment of a method for drawing an underground existing structure according to the present invention.
FIG. 4 is a view showing another embodiment of a method for drawing an underground existing structure according to the present invention.
FIG. 5 is a view showing still another embodiment of the drawing method of the existing underground structure according to the present invention.
FIG. 6 is a view showing still another embodiment of the method for extracting an underground existing structure according to the present invention.
[Explanation of symbols]
2 ... casing 3 ... existing structure 5 ... ground 7 ... drilled holes 11 ... steel pipe (auxiliary member)
12 ... Steel beam member (auxiliary member)
21 ... Slab

Claims (4)

  1. 地中の埋設された既設構造物を引き抜く引抜工法において、前記既設構造物の最下端に繋がる削孔を前記既設構造物に形成する第1工程と、
    前記削孔を介して前記既設構造物の最下端に向けて水を送給して前記既設構造物に対して浮力を与える第2工程と、
    前記既設構造物に対して浮力を与えた状態のまま前記既設構造物を吊り上げる第3工程と
    を備えたことを特徴とする地中既設構造物の引抜工法。
    In a drawing method for pulling out an existing structure buried underground, a first step of forming a hole in the existing structure that is connected to the lowermost end of the existing structure,
    A second step of supplying water toward the lowermost end of the existing structure through the hole to give buoyancy to the existing structure;
    And a third step of lifting the existing structure while applying buoyancy to the existing structure.
  2. 前記第2工程前に、前記既設構造物を囲むようにケーシングを地盤に回転推進して前記ケーシングの先端部を前記既設構造物の最下端以上の深さに到達させる第4工程をさらに備えた請求項1記載の地中既設構造物の引抜工法。Before the second step, a fourth step is further provided in which a casing is rotatably propelled to the ground so as to surround the existing structure so that a front end portion of the casing reaches a depth equal to or more than a lowermost end of the existing structure. The method for drawing out an existing underground structure according to claim 1.
  3. 前記第2工程前に、複数の鋼片を前記既設構造物の最下端の下方に位置させる第5工程をさらに備えた請求項2記載の地中既設構造物の引抜工法。The method of drawing out an existing underground structure according to claim 2, further comprising a fifth step of positioning a plurality of steel slabs below a lowermost end of the existing structure before the second step.
  4. 前記第3工程前に地盤表面の上方位置で前記既設構造物に補助部材を取り付ける第6工程と、
    前記第3工程とともに、前記既設構造物の引抜方向とほぼ平行な方向に前記補助部材を押し上げる第7工程と
    をさらに備えた請求項1ないし3のいずれかに記載の地中既設構造物の引抜工法。
    A sixth step of attaching an auxiliary member to the existing structure at a position above the ground surface before the third step;
    4. The underground existing structure withdrawal according to claim 1, further comprising a seventh step of pushing up the auxiliary member in a direction substantially parallel to the withdrawal direction of the existing structure together with the third step. Construction method.
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JP2015021230A (en) * 2013-07-16 2015-02-02 株式会社コプロス Removal method of existing manhole
JP2015048665A (en) * 2013-09-03 2015-03-16 大成建設株式会社 Removal method of existing pile
CN108797588A (en) * 2018-05-30 2018-11-13 江苏海上龙源风力发电有限公司 A kind of weak soil sea bed offshore wind turbine single-pile foundation overall pulling down auxiliary mould and remove technique
CN109610454A (en) * 2018-12-20 2019-04-12 上海勇创建设发展有限公司 A kind of underground obstacle barrier clearing device and its construction method

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CN102493454A (en) * 2011-11-24 2012-06-13 上海八洲建设工程有限公司 Ultrahigh-pressure aerodynamic force water-flushing pile extracting method of vibration-free flexible sleeve
JP2015021230A (en) * 2013-07-16 2015-02-02 株式会社コプロス Removal method of existing manhole
JP2015048665A (en) * 2013-09-03 2015-03-16 大成建設株式会社 Removal method of existing pile
CN108797588A (en) * 2018-05-30 2018-11-13 江苏海上龙源风力发电有限公司 A kind of weak soil sea bed offshore wind turbine single-pile foundation overall pulling down auxiliary mould and remove technique
CN109610454A (en) * 2018-12-20 2019-04-12 上海勇创建设发展有限公司 A kind of underground obstacle barrier clearing device and its construction method

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