JP3547096B2

JP3547096B2 - Fore pile construction method and drilling equipment used for it

Info

Publication number: JP3547096B2
Application number: JP19700694A
Authority: JP
Inventors: 憲雄山門; 巖中原
Original assignee: 日本基礎技術株式会社
Priority date: 1994-08-22
Filing date: 1994-08-22
Publication date: 2004-07-28
Anticipated expiration: 2019-07-28
Also published as: JPH0860976A

Description

【０００１】
【産業上の利用分野】
本発明は、トンネルや地下坑道等の掘削工事に於けるフォアパイルの造成工法とこれに用いる削孔装置に関する。
【０００２】
尚、本明細書に於て「フォアパイル」とは、硬化材と周辺土壌の混合によって形成された円柱状硬化層をいう。
【０００３】
【従来の技術】
近年、トンネル工事に於て、上部に構造物が建っていたり土塊の被りの薄い崩壊性地山での大断面トンネル建設が増加している。
【０００４】
このため、大型掘削機械に対応する補助工法として、掘削時の地山の先行緩みの防止や切羽，天端の崩壊を防止する目的で、トンネルの掘削に先立ち、切羽前方にトンネル断面に沿ってフォアパイルをアーチ状に造成することにより、切羽の安定を図る先受け工法が広く採用されている。
【０００５】
図５乃至図８は特公平４−４２５２０号公報に開示された先受け工法によるフォアパイルの造成工法を示し、この従来工法は、先ず、先端部にビット１と噴射装置３を装着した高圧噴射管５を坑部開削進行方向へ向けて開削対象地盤７の周縁地盤９に挿入し、所定位置まで地盤９を削孔する。
【０００６】
そして、所定位置まで地盤９を削孔したところで、図５及び図７に示すように高圧噴射管５に硬化材Ｇを圧送して噴射装置３から側方に高圧噴射し、高圧噴射管５を回転させ乍らこれを後退することにより地盤９にフォアパイル１１を造成するもので、図８に示すように斯かるフォアパイル１１を開削対象地盤７に沿って順次隣接造成してアーチ状の覆工体１３を構築した後、覆工体１３の内側の開削対象地盤７を覆工体１３の長さ以下の範囲で開削掘進して支保覆工を行う工程を繰り返し乍ら、トンネルを掘削している。
【０００７】
又、図９及び図１０は、図１１に示すダブルロータリー式の削孔装置を用いたフォアパイルの造成工法を示し、この従来工法は、図９に示すように先端にインナービット１５を装着した高圧噴射管１７を補強用鋼管１９内に挿入し、先端のインナービット１５を補強用鋼管１９の先端から突出させてこれらを夫々ロータリユニット２１，２２で同軸上に保持した後、高圧噴射管１７と補強用鋼管１９を同時に開削対象地盤の周縁地盤９に回転圧入し乍ら、高圧噴射管１７に装着した噴射装置２４から硬化材Ｇを高圧噴射して改良造成部ｍに円柱状の固化造成部２３を造成し、次いで、図１０の如く補強用鋼管１９を地中に残して高圧噴射管１７を引き抜くことにより、補強用鋼管１９を芯材とするフォアパイル２５を地盤９に造成するものである。
【０００８】
そして、前述した従来方法と同様、フォアパイル２５を順次隣接造成してアーチ状の覆工体を構築し、覆工体の内側の開削対象地盤を覆工体の長さ以下の範囲で開削掘進して支保覆工を行う工程を繰り返し乍ら、トンネルを掘削している。
【０００９】
その他、図１１中、２７は補強用鋼管１９の先端に装着された削孔ビット、２９は排土スイベル、３１は高圧スイベルを示す。
【００１０】
【発明が解決しようとする課題】
而して、図９乃至図１１に示す従来例にあっては、固化造成部２３の造成に伴い、高圧噴射管１７と補強用鋼管１９との間を通って排土スイベル２９から排泥が外部に排出されるが、これに伴い多くの未硬化の硬化材Ｇが排土と共に流出してしまい、又、この従来工法は、軟弱地盤の改良等の目的で地盤に対し垂直方向へ行っている従来のジェットグラウト工法を坑部開削進行方向へ向けて水平又はやや上向きにして行うものであるため、高圧噴射された未硬化の硬化材Ｇが地盤９と補強用鋼管１９との隙間から多量に流出してしまう不具合があった。
【００１１】
そして、図５乃至図８に示す従来例にあっても、高圧噴射管５から高圧噴射された硬化材Ｇが、排土と共に地盤９と高圧噴射管５との隙間から排泥として多量に流出してしまう欠点が指摘されている。
【００１２】
このように、従来工法にあっては、フォアパイルの造成に際し多くの硬化材が流出してしまうため、多量の硬化材を必要としていた。
又、排出量が流入量よりも多い（排泥過多）と、フォアパイルの上部と地盤との間に空洞が生じてしまう虞があり、フォアパイル上部と地盤との間に空洞が生じてしまうと覆工体周縁部の地盤の崩壊によって地盤全体が沈下してしまう虞があった。
【００１３】
本発明は斯かる実情に鑑み案出されたもので、フォアパイルの造成に当たり硬化材の過剰な流出を抑え、造成時の排泥過多による地盤の沈下を防止したフォアパイルの造成工法とこれに用いる削孔装置を提供することを目的とする。
【００１４】
【課題を解決するための手段】
斯かる目的を達成するため、請求項１に係るフォアパイルの造成工法は、補強用鋼管内に噴射管を挿入して、噴射管の先端に装着したインナービットを補強用鋼管の先端から突出させた後、これらを同時に坑部開削進行方向へ向けて開削対象地盤の周縁地盤に回転圧入し乍ら、噴射管に送水した削孔用水をインナービットの噴射孔から進行方向へ向け高圧噴射して地盤を削孔すると共に、噴射管の先端側に装着した削孔用水の噴射ノズルから削孔用水を補強用鋼管内後方に高圧噴射させて、その噴流による吸引力で補強用鋼管に設けた排泥吸込口から排土を吸引して排出し、所定位置まで地盤を削孔したところで、補強用鋼管と噴射管を同様に地盤へ回転圧入し且つインナービットから削孔用水を高圧噴射し乍ら、噴射管の先端側に装着した各噴射ノズルから硬化材と硬化促進材を、夫々、補強用鋼管に設けた噴射口より同時に側方へ高圧噴射して、周辺土壌と硬化材及び硬化促進材との混合によって固化造成部を速やかに固結造成すると共に、上述した噴射ノズルから高圧噴射される削孔用水の噴流による吸引力で排泥吸込口から排泥を吸引して、これを削孔用水で薄めてその固結を防止し乍ら排出し、所定位置まで固化造成部を造成した後、噴射管をインナービットと共に引き抜き回収して補強用鋼管を芯材とするフォアパイルを地盤中に造成するものである。
【００１５】
そして、フォアパイルの造成に用いる請求項２記載の削孔装置は、先端に削孔ビットが装着され、排泥吸込口と硬化材等の噴射口が先端側周壁に開口する補強用鋼管と、先端にインナービットが装着され、補強用鋼管の先端から当該インナービットを突出させて補強用鋼管内に挿入される三重噴射管と、三重噴射管を回転且つ前後方向へ移動させる回転駆動機構と、上記補強用鋼管を回転且つ前方へ移動させる回転駆動機構とで構成され、三重噴射管は、補強用鋼管の噴射口から硬化材を側方へ高圧噴射する噴射ノズルが装着された硬化材供給管と、補強用鋼管の噴射口から硬化促進材を側方へ高圧噴射する噴射ノズルが装着された硬化促進材供給管と、インナービットに設けられた削孔用水噴射孔と連通する削孔用水注水管とからなり、削孔用水注水管には、排泥吸込口のインナービット側に設置され、補強用鋼管内後方へ削孔用水を高圧噴射する噴射ノズルが装着されていることを特徴とする。
【００１６】
【作用】
請求項１に係るフォアパイルの造成工法によれば、補強用鋼管内に噴射管を挿入して、噴射管の先端に装着したインナービットを補強用鋼管の先端から突出させた後、これらを同時に坑部開削進行方向へ向けて開削対象地盤の周縁地盤に回転圧入し乍ら、噴射管に送水した削孔用水をインナービットの噴射孔から進行方向へ向け高圧噴射して地盤を削孔すると共に、噴射管の先端側に装着した削孔用水の噴射ノズルから削孔用水を補強用鋼管内後方に高圧噴射させて、その噴流による吸引力で補強用鋼管に設けた排泥吸込口から排土を吸引して排出し、所定位置まで地盤を削孔したところで、補強用鋼管と噴射管を同様に地盤へ回転圧入し且つインナービットから削孔用水を高圧噴射し乍ら、噴射管の先端側に装着した各噴射ノズルから硬化材と硬化促進材を、夫々、補強用鋼管に設けた噴射口より同時に側方へ高圧噴射して、周辺土壌と硬化材及び硬化促進材との混合によって固化造成部を速やかに固結造成すると共に、上述した噴射ノズルから高圧噴射される削孔用水の噴流による吸引力で排泥吸込口から排泥を吸引して、これを削孔用水で薄めてその固結を防止し乍ら排出し、所定位置まで固化造成部を造成した後、噴射管をインナービットと共に引き抜き回収することにより、補強用鋼管を芯材とするフォアパイルが地盤中に造成されることとなる。
【００１７】
又、請求項２に係る削孔装置によれば、当該削孔装置は従来の削孔装置と同様、削孔機のブームに搭載されて使用され、先ず、削孔装置を搭載した削孔機を開削対象地盤の前に走行してベースロッドで削孔装置の高さ方向を定め、併せて位置操作機構で削孔装置の仰向角度と左右傾斜による対象地盤壁面との位置を確定する。
【００１８】
そして、削孔用水注水管内に削孔用水を送水して、インナービットから削孔用水を進行方向へ向けて高圧噴射し、同時に回転駆動機構により三重噴射管と補強用鋼管を地盤に回転圧入して、改良造成部の手前まで地盤を削孔ビットとインナービット，削孔用水で削孔する。
【００１９】
このとき、削孔用水の一部は削孔用水注水管の噴射ノズルから補強用鋼管内の後方へ向けて高圧噴射されているので、その噴流により、削孔された排土は削孔用水と共に排泥吸込口から吸引されて補強用鋼管と硬化材供給管の間を通って補強用鋼管の後方から外部に排出される。
【００２０】
而して、斯様に所定位置まで地盤の削孔を終えた後、噴射ノズルから夫々硬化促進材と硬化材を側方へ高圧噴射させて、補強用鋼管及び三重噴射管を地盤中に更に回転圧入させていくと、周辺土壌と硬化材及び硬化促進材とが混合して地盤中に固化造成部が速やかに造成される。そして、削孔用水の一部は依然として噴射ノズルから補強用鋼管内の後方へ高圧噴射されているので、排土と硬化材，硬化促進材が混合した排泥がその噴流で排泥吸込口から吸引される。そして、排泥が排泥吸込口から吸引されると、噴射ノズルから噴射された削孔用水によって硬化材が薄められるため、排泥中の硬化材が硬化促進材と固結せず、排泥がスムーズに排出されることとなる。
【００２１】
このようにして地盤の改良造成部に固化造成部を造成した後、回転駆動機構を後退させて三重噴射管をインナービットと共に引き抜き回収すれば、補強用鋼管を芯材とするフォアパイルの造成が完了する。
【００２２】
【実施例】
以下、本発明の実施例を図面に基づき詳細に説明する。
図１は請求項２に係る削孔装置の第一実施例によるフォアパイル造成時の地盤の断面図を示し、図に於て、３３は先端にリングビット３５が取り付けられた円筒状の補強用鋼管、３７は当該補強用鋼管３３内に挿入された三重噴射管で、三重噴射管３７の先端に装着したインナービット３９が、補強用鋼管３３の先端から突出した構造となっている。
【００２３】
そして、図示しないが補強用鋼管３３と三重噴射管３７の後端には、夫々、回転駆動機構が接続されており、三重噴射管３７は当該回転駆動機構によって矢印方向へ回転且つ前後方向へ移動可能とされ、同様に補強用鋼管３３も、回転駆動機構によって三重噴射管３７と同時に矢印方向へ回転し、又、前方へ移動可能となっている。
【００２４】
而して、上記三重噴射管３７は、図１及び図２に示すように中央に位置してインナービット３９の削孔用水噴射孔４１に連通する削孔用水注水管４３と、当該削孔用水注水管４３よりも大径な硬化材供給管４５と、更に当該硬化材供給管４５よりも大径な硬化促進材供給管４７とからなり、これらは、夫々、スペーサ４９，５１，５３を介して補強用鋼管３３と同軸上に配置されている。
【００２５】
そして、削孔用水注水管４３に送水された削孔用水Ｗが削孔用水噴射孔４１から進行方向へ高圧噴射されて、地盤５５を削孔するようになっている。
又、最も外側に位置する硬化促進材供給管４７の先端側周壁には、水ガラス等の硬化促進材Ｇ′を側方へ高圧噴射する噴射ノズル５７が装着され、更にその内側に位置する硬化材供給管４５には、硬化促進材供給管４７の周壁を貫通する通路管５９がその周壁に挿着され、その先端にセメントミルク等の硬化材Ｇを側方へ高圧噴射する噴射ノズル６１が噴射ノズル５７のやや前方に位置して装着されている。
【００２６】
一方、補強用鋼管３３の周壁には、上記噴射ノズル５７，６１に対応して２つの噴射口６３，６５前後方向に形成されており、補強用鋼管３３と三重噴射管３７を同時に地盤５５に回転圧入し乍ら、インナービット３９から削孔用水Ｗを進行方向へ向けて高圧噴射し、且つ噴射ノズル５７，６１から夫々硬化材Ｇと硬化促進材Ｇ′を同時に側方へ高圧噴射すると、周辺土壌と硬化材Ｇ及び硬化促進材Ｇ′とが混合して、地盤５５中に約３０秒で固結する固化造成部６７が形成されるようになっている。
【００２７】
又、補強用鋼管３３には、上記噴射口６３，６５の反対側に排泥吸込口６９が開口している。そして、削孔用水注水管４３には、硬化材供給管４５及び硬化促進材供給管４７の周壁を貫通してＬ字状の通路管７１が挿着されており、当該通路管７１の先端に装着された噴射ノズル７３が、上記排泥吸込口６９のインナービット３９側に配置されている。
【００２８】
そして、削孔用水注水管４３に供給された削孔用水Ｗの一部が通路管７１を経て上記噴射ノズル７３から補強用鋼管３３内の後方へ高圧噴射されると、排土と硬化材Ｇ，硬化促進材Ｇ′が混合した排泥Ｓがその噴流で排泥吸込口６９から吸引され、そして、噴補強用鋼管３３と硬化促進材供給管４７の間を通って補強用鋼管３３の後端側に設けた排泥口７５から排出されるようになっているが、上述したように硬化材Ｇは硬化促進材Ｇ′と反応して速やかに固結する。
【００２９】
然し、排泥Ｓが排泥吸込口６９から吸引されると、噴射ノズル７３から噴射された削孔用水Ｗによって硬化材Ｇの濃度が薄くなるため、排泥Ｓ中の硬化材Ｇが硬化促進材Ｇ′と固結せず、排泥口７５から排泥Ｓがスムーズに排出できるようになっている。
【００３０】
本実施例に係る削孔装置７７はこのように構成されており、当該削孔装置７７を用いて請求項１に係る造成工法の一実施例は以下の如く実施される。
削孔装置７７は図１１に示す削孔装置と同様、図示しない削孔機のブームに搭載されて使用され、先ず、削孔装置７７を搭載した削孔機を開削対象地盤の前に走行してベースロッドで削孔装置７７の高さ方向を定め、併せて位置操作機構で削孔装置７７の仰向角度と左右傾斜による対象地盤壁面との位置を確定する。
【００３１】
そして、削孔用水注水管４３内に削孔用水Ｗを送水して、インナービット３９から削孔用水Ｗを進行方向へ向けて高圧噴射し、同時に回転駆動機構により三重噴射管３７と補強用鋼管３３を地盤５５に回転圧入して、図３に示す改良造成部ｍの手前まで地盤５５をリングビット３５とインナービット３９，削孔用水Ｗで削孔する。
【００３２】
このとき、削孔用水Ｗの一部は噴射ノズル７３から補強用鋼管３３内の後方へ向けて高圧噴射されているので、その噴流により、削孔された排土は削孔用水Ｗと共に排泥吸込口６９から吸引されて補強用鋼管３３と硬化材供給管４５の間を通って排泥口７５から外部に排出される。
【００３３】
而して、斯様に所定位置まで地盤５５の削孔を終えた後、噴射ノズル５７，６１から夫々硬化促進材Ｇ′と硬化材Ｇを側方へ高圧噴射させて、補強用鋼管３３及び三重噴射管３７を地盤５５中に更に回転圧入させていくと、周辺土壌と硬化材Ｇ及び硬化促進材Ｇ′とが混合して地盤５５中に固化造成部６７が速やかに造成される。そして、削孔用水Ｗの一部は依然として噴射ノズル７３から補強用鋼管３３内の後方へ高圧噴射されているので、排土と硬化材Ｇ，硬化促進材Ｇ′が混合した排泥Ｓがその噴流で排泥吸込口６９から吸引される。そして、排泥Ｓが排泥吸込口６９から吸引されると、噴射ノズル７３から噴射された削孔用水Ｗによって硬化材Ｇが薄められるため、排泥Ｓ中の硬化材Ｇが硬化促進材Ｇ′と固結せず、排泥口７５から排泥Ｓがスムーズに排出されることとなる。
【００３４】
このようにして改良造成部ｍに固化造成部６７を造成した後、回転駆動機構を後退させて図３の如く三重噴射管３７をインナービット３９と共に引き抜き回収すれば、補強用鋼管３３を芯材とするフォアパイルの造成が完了する。
【００３５】
そして、斯かる工程を順次繰り返してフォアパイルを順次隣接造成することにより、覆工体が坑部開口周縁に沿ってアーチ状に構築されて切羽の安定性が確保されるので、従来と同様、覆工体の内側の開削対象地盤を、構築した覆工体の長さ以下の範囲で開削掘進してトンネルの掘削が行われることとなる。
【００３６】
このように、上記削孔装置７７とこれを用いた本実施例の造成工法によっても、図９以下に示す従来例と同等、補強用鋼管３３を芯材とするフォアパイルの造成が可能である。
【００３７】
そして、上述した実施例では、硬化材Ｇと硬化促進材Ｇ′を用いて瞬結性の固化造成部６７を地盤５５中に形成していくため、従来の如く補強用鋼管３３と地盤５５との隙間を通って未硬化の硬化材Ｇが流出してしまう虞がないし、又、噴射ノズル６１から噴射された硬化材Ｇは硬化促進材Ｇ′によって速やかに固結するため、固化造成部６７の造成に伴い補強用鋼管３３と三重噴射管３７との間を通って外部に排出される未硬化の硬化材Ｇの流出量も減少することとなる。
【００３８】
従って、上記削孔装置７７を用いた本発明工法の一実施例によれば、図５以下に示す従来工法に比し、造成時の排泥過多によってフォアパイルの上部と地盤５５との間に空洞が生じてしまう虞が解消されると共に、硬化材Ｇの無駄な流出を防止して使用量を軽減することが可能である。
【００３９】
更に、上述したように排泥Ｓが排泥吸込口６９から吸引されても、噴射ノズル７３から噴射された削孔用水Ｗによって硬化材Ｇが薄められるため、排泥Ｓ中の硬化材Ｇが硬化促進材Ｇ′と固結して目詰まりを起こす虞がない。
【００４０】
従って、排泥口７５から排泥Ｓがスムーズに排出され、効率のよいフォアパイルの造成が可能となる。
然も、本実施例に係る削孔装置７７は、既存の削孔機のブームに搭載して使用することができるため、格別既存の削孔機のブーム等の改良を必要としない利点を有する。
【００４１】
図４は請求項２に係る削孔装置の第二実施例の要部断面図を示し、図示するように本実施例に係る削孔装置７９は、上述した硬化促進材Ｇ′の噴射ノズル５７に代え、噴射ノズル６１の周囲を覆うように噴射ノズル８１を硬化促進材供給管４７の外周に装着して、噴射ノズル６１による硬化材Ｇと噴射ノズル８１による硬化促進材Ｇ′の混合液を、補強用鋼管３３に設けた噴射口６５から同時に側方に高圧噴射させるようにしたものである。
【００４２】
尚、その他の構成は上記第一実施例の削孔装置７７と同様であるので、同一のものには同一符号を付してそれらの説明は省略する。
而して、本実施例に係る削孔装置７９を用いても、上記第一実施例の削孔装置７７を用いた場合と同様、所期の目的を達成することが可能である。
【００４３】
【発明の効果】
以上述べたように、請求項１に記載のフォアパイルの造成工法によれば、切羽前方にトンネル断面に沿ってフォアパイルを造成していくに当たり、硬化材と硬化促進材を用いて瞬結性の固化造成部を地盤中に形成していくため、従来の如く補強用鋼管と地盤との隙間を通って未硬化の硬化材が流出してしまう虞がないし、噴射ノズルから地盤中に噴射された硬化材は硬化促進材によって速やかに固結するため、固化造成部の造成に伴い補強用鋼管と噴射管との間を通って外部に排出される未硬化の硬化材の流出量も減少することとなる。
【００４４】
従って、従来工法に比し、造成時の排泥過多によってフォアパイルの上部と地盤との間に空洞が生じてしまう虞が解消されると共に、硬化材の無駄な流出を防いで硬化材の使用量を軽減することが可能である。
【００４５】
更に、補強用鋼管の排泥吸込口から吸引された排泥は、噴射ノズルから噴射された削孔用水によって硬化材が薄められるため、排泥中の硬化材が硬化促進材と固結して目詰まりを起こす虞がなく、排泥がスムーズに排出され、効率のよいフォアパイルの造成が可能である。
【００４６】
同様に、請求項２に記載の削孔装置によっても、硬化材と硬化促進材を用いて瞬結性の固化造成部を地盤中に形成するため、補強用鋼管と地盤との隙間を通って未硬化の硬化材が流出してしまう虞がないし、噴射ノズルから地盤中に噴射された硬化材は硬化促進材によって速やかに固結するため、固化造成部の造成に伴い補強用鋼管と三重噴射管との間を通って外部に排出される未硬化の硬化材の流出量も減少することとなる。
【００４７】
従って、造成時の排泥過多によってフォアパイルの上部と地盤との間に空洞が生じてしまう虞が解消されると共に、硬化材の無駄な流出を防止して硬化材の使用量を軽減することが可能となる。
【００４８】
又、排泥が補強用鋼管の排泥吸込口から吸引されても、噴射ノズルから噴射された削孔用水によって硬化材が薄められるため、排泥中の硬化材が硬化促進材と固結して目詰まりを起こす虞がなく、排泥のスムーズな排出が可能である。
【００４９】
更に又、本発明に係る削孔装置は、既存の削孔機のブームに搭載して使用することができるため、格別既存の削孔機の改良を必要としない利点を有する。
【図面の簡単な説明】
【図１】請求項２に係る削孔装置の第一実施例によるフォアパイル造成時の地盤の断面図である。
【図２】図１のＩＩ−ＩＩ線断面図である。
【図３】フォアパイル造成時に於ける三重噴射管の引き抜き状態を示す地盤の断面図である。
【図４】請求項２に係る削孔装置の第二実施例の要部断面図である。
【図５】従来のフォアパイルの造成工法を示す説明図である。
【図６】トンネルの横断面図である。
【図７】フォアパイルの造成工法を示す説明図である。
【図８】フォアパイルによる覆工体を形成したトンネルの横断面図である。
【図９】従来の他のフォアパイルの造成工法を示す説明図である。
【図１０】補強用鋼管から高圧噴射管を引き抜いた状態を示す説明図である。
【図１１】従来の削孔装置の側面図である。
【符号の説明】
３３補強用鋼管
３５リングビット
３７三重噴射管
３９インナービット
４１削孔用水噴射孔
４３削孔用水注水管
４５硬化材供給管
４７硬化促進材供給管
５５地盤
５７，６１，７３，８１噴射ノズル
６３，６５噴射口
６７固化造成部
６９排泥吸込口
７５排泥口
７７，７９削孔装置
Ｇ硬化材
Ｇ′ 硬化促進材
Ｓ排泥
Ｗ削孔用水[0001]
[Industrial applications]
The present invention relates to a method for forming a fore pile in excavation work such as a tunnel or an underground tunnel, and a drilling device used for the method.
[0002]
In addition, in this specification, "fore pile" means the columnar hardened layer formed by mixing a hardening material and surrounding soil.
[0003]
[Prior art]
2. Description of the Related Art In recent years, in tunnel construction, construction of large-section tunnels in collapsed grounds where structures are erected on top of the ground or where the clod of earth is thin is increasing.
[0004]
Therefore, as an auxiliary method corresponding to large excavating machines, in order to prevent the ground from loosening at the time of excavation and to prevent the collapse of the face and the crown, the excavation along the tunnel section ahead of the face before excavation of the tunnel A front receiving method for stabilizing a face by forming a fore pile in an arch shape is widely adopted.
[0005]
FIGS. 5 to 8 show a construction method of a fore pile by a prior receiving method disclosed in Japanese Patent Publication No. 4-42520. In this conventional method, first, a high-pressure injection in which a bit 1 and an injection device 3 are mounted at a tip end portion is shown. The pipe 5 is inserted into the peripheral ground 9 of the ground 7 to be cut in the direction of the pit opening progress, and the ground 9 is drilled to a predetermined position.
[0006]
Then, when the ground 9 is drilled to a predetermined position, as shown in FIGS. 5 and 7, the hardening material G is pressure-fed to the high-pressure injection pipe 5 and high-pressure injection is laterally injected from the injection device 3. The fore pile 11 is formed on the ground 9 by retreating while rotating, and as shown in FIG. 8, the fore pile 11 is sequentially formed adjacently along the ground 7 to be cut to form an arch-shaped cover. After constructing the body 13, the tunnel is excavated while repeating the step of performing the digging and excavation of the ground 7 to be cut inside the lining 13 within the length of the lining 13 and performing the supporting lining. ing.
[0007]
9 and 10 show a construction method of a fore pile using the double rotary type drilling device shown in FIG. 11, and in this conventional method, an inner bit 15 is attached to the tip as shown in FIG. After inserting the high-pressure injection pipe 17 into the reinforcing steel pipe 19 and projecting the inner bit 15 at the tip from the tip of the reinforcing steel pipe 19 and holding them coaxially with the rotary units 21 and 22, respectively, And the reinforcing steel pipe 19 are simultaneously rotary-pressed into the peripheral ground 9 of the ground to be cut, and at the same time, the hardening material G is injected at high pressure from the injection device 24 mounted on the high-pressure injection pipe 17 to form a solidified column in the improved formation section m. A fore pile 25 having the reinforcing steel pipe 19 as a core material is formed on the ground 9 by forming the part 23 and then pulling out the high-pressure injection pipe 17 while leaving the reinforcing steel pipe 19 in the ground as shown in FIG. so That.
[0008]
Then, in the same manner as in the conventional method described above, the fore pile 25 is successively formed adjacently to form an arch-shaped lining, and the ground to be cut inside the lining is excavated within the range of the length of the lining. The tunnel is excavated while repeating the process of lining the shore.
[0009]
In addition, in FIG. 11, reference numeral 27 denotes a drill bit attached to the tip of the reinforcing steel pipe 19, reference numeral 29 denotes an earth removal swivel, and reference numeral 31 denotes a high-pressure swivel.
[0010]
[Problems to be solved by the invention]
Thus, in the conventional example shown in FIGS. 9 to 11, with the formation of the solidified formation portion 23, the mud discharged from the earth removal swivel 29 passes between the high-pressure injection pipe 17 and the reinforcing steel pipe 19. Although it is discharged to the outside, a lot of uncured hardening material G flows out along with the discharge along with this, and this conventional method is performed in the vertical direction with respect to the ground for the purpose of improving soft ground. The conventional jet grouting method is performed in a horizontal or slightly upward direction in the direction of pit excavation, so that a large amount of uncured hardened material G injected by high pressure flows from a gap between the ground 9 and the reinforcing steel pipe 19. There was a problem that it leaked out.
[0011]
Also in the conventional example shown in FIGS. 5 to 8, a large amount of the hardened material G ejected from the high-pressure injection pipe 5 at high pressure flows out of the gap between the ground 9 and the high-pressure injection pipe 5 together with the discharged soil. It has been pointed out that it does.
[0012]
As described above, according to the conventional method, a large amount of the hardening material is required because a large amount of the hardening material flows out when the fore pile is formed.
If the amount of discharge is larger than the amount of inflow (excessive mud), a cavity may be formed between the upper part of the fore pile and the ground, and a cavity may be formed between the upper part of the fore pile and the ground. And there is a possibility that the entire ground may sink due to the collapse of the ground at the periphery of the lining body.
[0013]
The present invention has been devised in view of the above circumstances, and a method of forming a fore pile, which suppresses excessive outflow of hardened material during formation of the fore pile and prevents settlement of the ground due to excessive discharge of sludge at the time of formation, and It is an object to provide a drilling device to be used.
[0014]
[Means for Solving the Problems]
In order to achieve such an object, in the fore pile forming method according to claim 1, the injection pipe is inserted into the reinforcing steel pipe, and the inner bit attached to the tip of the injection pipe is projected from the tip of the reinforcing steel pipe. After that, while simultaneously rotating and press-fitting them into the peripheral ground of the ground to be excavated in the direction of pit excavation, high-pressure injection of drilling water sent to the injection pipe from the injection hole of the inner bit in the traveling direction While drilling the ground, the drilling water is sprayed from the drilling water injection nozzle attached to the tip of the injection pipe at a high pressure to the rear of the reinforcing steel pipe at high pressure, and the suction force generated by the jet flows into the drainage pipe. When the ground was sucked and discharged from the mud suction port and the ground was drilled to a predetermined position, the reinforcing steel pipe and the injection pipe were similarly rotationally pressed into the ground, and the drilling water was injected at a high pressure from the inner bit. Attached to the tip side of the injection tube The hardening material and the hardening accelerator are simultaneously sprayed from the spray nozzle to the side at high pressure from the spray holes provided in the reinforcing steel pipe, and the solidified formation is quickly formed by mixing the surrounding soil with the hardening material and the hardening accelerator. In addition to consolidation, the above-mentioned injection nozzle sucks the mud from the mud suction port with the suction force of the drilling water jet injected at high pressure from the injection nozzle and dilutes it with the drilling water to prevent the consolidation. Then, after forming the solidified formation part to a predetermined position, the injection pipe is pulled out and collected together with the inner bit, and a fore pile having a reinforcing steel pipe as a core material is formed in the ground.
[0015]
The drilling device according to claim 2, wherein the drilling device is used for forming a fore pile, a drilling bit is attached to a tip end, and a reinforcing steel pipe in which an exhaust port such as a mud suction port and a hardening material opens in a tip side peripheral wall, An inner bit is attached to the tip, a triple injection pipe inserted into the reinforcing steel pipe by projecting the inner bit from the tip of the reinforcing steel pipe, and a rotation drive mechanism that rotates the triple injection pipe and moves the pipe in the front-back direction, A rotary drive mechanism for rotating and moving the reinforcing steel pipe forward, the triple injection pipe being a hardening material supply pipe equipped with an injection nozzle for injecting high-pressure hardening material laterally from an injection port of the reinforcing steel pipe. And a hardening accelerator supply pipe equipped with an injection nozzle for high-pressure injection of the hardening accelerator from the injection port of the reinforcing steel pipe to the side, and a drilling water injection hole communicating with the drilling water injection hole provided in the inner bit. Water pipe The water injection pipe is installed in the inner bit side of the waste sludge inlet, the injection nozzle for high-pressure injection of drilling water to the reinforcing steel within the rear, characterized in that it is fitted.
[0016]
[Action]
According to the construction method of the fore pile according to claim 1, the injection pipe is inserted into the steel pipe for reinforcement, and the inner bit attached to the tip of the injection pipe is made to protrude from the tip of the steel pipe for reinforcement. While rotating and press-fitting into the peripheral ground of the ground to be excavated in the direction of pit excavation, the drilling water sent to the injection pipe is injected at high pressure from the injection hole of the inner bit in the traveling direction to cut the ground. Drilling water is injected at high pressure from the drilling water injection nozzle attached to the tip of the injection pipe to the rear inside the reinforcing steel pipe, and the suction force of the jet stream removes the soil from the mud suction port provided in the reinforcing steel pipe. When the ground is drilled to a predetermined position, the steel pipe for reinforcement and the injection pipe are similarly rotationally pressed into the ground, and high-pressure injection of drilling water is performed from the inner bit, while the tip side of the injection pipe. Curing from each injection nozzle attached to And the hardening accelerator, respectively, are simultaneously injected to the side from the injection port provided in the reinforcing steel pipe at a high pressure, and the solidified formation portion is quickly solidified by mixing the surrounding soil with the hardening material and the hardening accelerator. By sucking the mud from the mud suction port with the suction force of the drilling water jet injected at a high pressure from the above-described injection nozzle, diluting it with drilling water and discharging it while preventing its consolidation, After forming the solidified formation part to a predetermined position, the injection pipe is pulled out and collected together with the inner bit, whereby a fore pile having a reinforcing steel pipe as a core material is formed in the ground.
[0017]
According to the drilling device according to claim 2, the drilling device is used by being mounted on a boom of a drilling machine like a conventional drilling device. Is driven in front of the ground to be cut and the height direction of the drilling machine is determined by the base rod, and the position of the drilling machine is determined by the elevation angle and the lateral inclination of the drilling machine by the position operation mechanism.
[0018]
Then, water for drilling is fed into the water injection pipe for drilling, and water for drilling is jetted from the inner bit in the direction of travel at a high pressure. At the same time, the triple injection pipe and the steel pipe for reinforcement are rotationally pressed into the ground by a rotary drive mechanism. The ground is drilled with a drill bit, inner bit, and drilling water up to just before the improved formation section.
[0019]
At this time, part of the drilling water is injected at a high pressure from the injection nozzle of the drilling water injection pipe toward the rear inside the reinforcing steel pipe, so that the drilling removes the drilled soil together with the drilling water. It is sucked from the mud suction port and is discharged from the rear of the reinforcing steel pipe to the outside through the space between the reinforcing steel pipe and the hardening material supply pipe.
[0020]
Thus, after finishing the drilling of the ground to the predetermined position in this way, the hardening accelerator and the hardening material are respectively injected at high pressure from the injection nozzle to the side, and the reinforcing steel pipe and the triple injection pipe are further injected into the ground. When the rotary press-fitting is performed, the surrounding soil, the hardening material and the hardening accelerator are mixed, and the solidified formation portion is quickly formed in the ground. Since part of the drilling water is still injected from the injection nozzle to the rear of the reinforcing steel pipe at a high pressure, the mixed waste water and the hardening material and the hardening accelerator are discharged from the wastewater suction port by the jet. It is sucked. Then, when the mud is sucked from the mud suction port, the hardening material is diluted by the drilling water injected from the injection nozzle, so that the hardened material in the sludge does not solidify with the hardening accelerating material. Will be discharged smoothly.
[0021]
In this way, after forming the solidified formation part in the improved formation part of the ground, if the rotary drive mechanism is retracted and the triple injection pipe is pulled out and collected together with the inner bit, the fore pile with the reinforcing steel pipe as the core material can be formed. Complete.
[0022]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a sectional view of the ground at the time of forming a fore pile according to a first embodiment of the drilling device according to the second embodiment. In the drawing, reference numeral 33 denotes a cylindrical reinforcing member having a ring bit 35 attached to the tip. The steel pipe 37 is a triple injection pipe inserted into the reinforcing steel pipe 33. The inner bit 39 attached to the tip of the triple injection pipe 37 projects from the tip of the reinforcing steel pipe 33.
[0023]
Although not shown, a rotary drive mechanism is connected to the reinforcing steel pipe 33 and the rear end of the triple injection pipe 37, respectively, and the triple injection pipe 37 is rotated in the arrow direction and moved in the front-rear direction by the rotary drive mechanism. Similarly, the reinforcing steel pipe 33 is also rotated in the direction of the arrow at the same time as the triple injection pipe 37 by the rotary drive mechanism, and is also movable forward.
[0024]
As shown in FIGS. 1 and 2, the triple injection pipe 37 includes a drilling water injection pipe 43 which is located at the center and communicates with the drilling water injection hole 41 of the inner bit 39, and the drilling water injection pipe 43. It comprises a hardening material supply pipe 45 larger in diameter than the water injection pipe 43, and a hardening accelerator supply pipe 47 larger in diameter than the hardening material supply pipe 45, and these are interposed through spacers 49, 51 and 53, respectively. And is disposed coaxially with the reinforcing steel pipe 33.
[0025]
Then, the drilling water W sent to the drilling water injection pipe 43 is injected at a high pressure from the drilling water injection hole 41 in the traveling direction to drill the ground 55.
An injection nozzle 57 for injecting a high-pressure injection of a hardening accelerator G 'such as water glass to the side is attached to the outer peripheral wall of the hardening accelerator supply pipe 47 located at the outermost side, and the hardening accelerator located further inside. A passage pipe 59 penetrating through the peripheral wall of the hardening accelerator supply pipe 47 is inserted into the peripheral wall of the material supply pipe 45, and an injection nozzle 61 for injecting the hardening material G such as cement milk to the side at a high pressure at the tip thereof. It is mounted slightly forward of the injection nozzle 57.
[0026]
On the other hand, on the peripheral wall of the reinforcing steel pipe 33, two injection ports 63, 65 are formed in the front-rear direction corresponding to the injection nozzles 57, 61, and the reinforcing steel pipe 33 and the triple injection pipe 37 are simultaneously formed on the ground 55. While rotating and press-fitting, high-pressure injection of drilling water W from the inner bit 39 in the traveling direction and high-pressure injection of the hardening material G and the hardening accelerator G 'simultaneously from the injection nozzles 57 and 61 to the sides, respectively, The surrounding soil is mixed with the hardening material G and the hardening accelerator G 'so that a solidified formation 67 is formed in the ground 55 in about 30 seconds.
[0027]
Further, a drainage suction port 69 is opened in the reinforcing steel pipe 33 on a side opposite to the injection ports 63 and 65. An L-shaped passage pipe 71 is inserted into the drilling water injection pipe 43 so as to penetrate through the peripheral walls of the hardening material supply pipe 45 and the hardening accelerating material supply pipe 47. The attached injection nozzle 73 is arranged on the inner bit 39 side of the above-mentioned mud suction port 69.
[0028]
Then, when a part of the drilling water W supplied to the drilling water injection pipe 43 is injected through the passage pipe 71 from the injection nozzle 73 to the rear of the reinforcing steel pipe 33 at a high pressure, the earth discharging and the hardening material G are discharged. And the hardening accelerator G 'are mixed, and the mud S mixed with the hardening accelerator G' is sucked from the mud suction inlet 69 by the jet, and passes through the space between the jet reinforcing steel pipe 33 and the hardening accelerator supply pipe 47 and is located behind the reinforcing steel pipe 33. The hardening material G reacts with the hardening accelerator G 'and solidifies quickly, as described above.
[0029]
However, when the sludge S is sucked from the sludge suction port 69, the concentration of the hardening material G is reduced by the drilling water W injected from the injection nozzle 73, so that the hardening material G in the sludge S accelerates hardening. Without being consolidated with the material G ', the sludge S can be smoothly discharged from the sludge outlet 75.
[0030]
The drilling device 77 according to the present embodiment is configured as described above, and an embodiment of the construction method according to claim 1 is performed using the drilling device 77 as follows.
The drilling device 77 is used by being mounted on a boom of a drilling machine (not shown), similarly to the drilling device shown in FIG. 11. First, the drilling device equipped with the drilling device 77 travels in front of the ground to be cut. Then, the height direction of the drilling device 77 is determined by the base rod, and the position of the drilling device 77 on the target ground wall surface by the elevation angle and the left-right inclination is determined by the position operation mechanism.
[0031]
Then, the drilling water W is supplied into the drilling water injection pipe 43, and the drilling water W is injected from the inner bit 39 toward the traveling direction at a high pressure, and at the same time, the triple injection pipe 37 and the reinforcing steel pipe are rotated by the rotary drive mechanism. 33 is rotationally pressed into the ground 55, and the ground 55 is drilled with the ring bit 35, the inner bit 39, and the drilling water W up to just before the improved formation portion m shown in FIG.
[0032]
At this time, since a part of the drilling water W is injected from the injection nozzle 73 toward the rear of the reinforcing steel pipe 33 at a high pressure, the excavated soil is discharged together with the drilling water W by the jet flow. It is sucked from the suction port 69 and passes through the space between the reinforcing steel pipe 33 and the hardening material supply pipe 45 to be discharged to the outside from the mud discharge port 75.
[0033]
Thus, after the drilling of the ground 55 to the predetermined position is completed, the hardening accelerator G ′ and the hardening material G are jetted from the jet nozzles 57 and 61 to the side at high pressure, respectively. When the triple injection pipe 37 is further rotationally pressed into the ground 55, the surrounding soil, the hardening material G and the hardening accelerator G 'are mixed, and the solidified formation portion 67 is quickly formed in the ground 55. Then, since a part of the drilling water W is still injected from the injection nozzle 73 to the rear of the reinforcing steel pipe 33 at a high pressure, the discharged soil and the wastewater S in which the hardening material G and the hardening accelerator G 'are mixed are discharged. It is sucked from the mud suction port 69 by the jet. Then, when the sludge S is sucked from the sludge suction port 69, the hardening material G is diluted by the drilling water W injected from the injection nozzle 73, so that the hardening material G in the sludge S becomes the hardening accelerator G ′, And the sludge S is discharged smoothly from the sludge outlet 75.
[0034]
After the solidified formation part 67 is formed in the improved formation part m in this way, the triple injection pipe 37 is pulled out and collected together with the inner bit 39 as shown in FIG. Construction of the fore pile is completed.
[0035]
And by repeating such a process sequentially and forming the fore pile sequentially adjacently, the lining body is constructed in an arch shape along the periphery of the opening of the pit, and the stability of the face is secured. Tunnel excavation is performed by excavating the ground to be excavated on the inner side of the lining body within a range not more than the length of the constructed lining body.
[0036]
As described above, even with the drilling device 77 and the forming method of the present embodiment using the same, it is possible to form a fore pile using the reinforcing steel pipe 33 as a core material, as in the conventional example shown in FIG. .
[0037]
In the above-described embodiment, the hardening material G and the hardening accelerator G ′ are used to form the solidified solidified portion 67 in the ground 55, so that the reinforcing steel pipe 33 and the ground 55 There is no danger that the uncured hardening material G will flow out through the gap, and the hardening material G injected from the injection nozzle 61 will be quickly consolidated by the hardening accelerator G '. As a result, the outflow of the uncured hardened material G discharged to the outside through the space between the reinforcing steel pipe 33 and the triple injection pipe 37 is also reduced.
[0038]
Therefore, according to an embodiment of the present invention using the drilling device 77, compared to the conventional method shown in FIG. It is possible to eliminate the possibility that a cavity is formed, to prevent the hardening material G from being wasted, and to reduce the amount of use.
[0039]
Further, as described above, even if the sludge S is sucked from the sludge suction port 69, the hardening material G is thinned by the drilling water W injected from the injection nozzle 73, so that the hardening material G in the sludge S There is no possibility of clogging due to solidification with the curing accelerator G '.
[0040]
Therefore, the mud S is discharged smoothly from the mud outlet 75, and the fore pile can be efficiently formed.
Needless to say, since the drilling device 77 according to the present embodiment can be used by being mounted on a boom of an existing drilling machine, it has an advantage that it does not require any particular improvement of the boom of an existing drilling machine. .
[0041]
FIG. 4 is a sectional view of a main part of a second embodiment of the drilling device according to the second embodiment. As shown in the drawing, the drilling device 79 according to the present embodiment employs the above-described injection nozzle 57 for the hardening accelerator G ′. Instead, an injection nozzle 81 is attached to the outer periphery of the hardening accelerator supply pipe 47 so as to cover the periphery of the injection nozzle 61, and a mixed liquid of the hardening material G by the injection nozzle 61 and the hardening accelerator G ′ by the injection nozzle 81 is discharged. The high-pressure injection is simultaneously performed to the side from the injection port 65 provided in the reinforcing steel pipe 33.
[0042]
Since other configurations are the same as those of the drilling device 77 of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.
Thus, even when the drilling device 79 according to the present embodiment is used, the intended purpose can be achieved similarly to the case where the drilling device 77 according to the first embodiment is used.
[0043]
【The invention's effect】
As described above, according to the fore pile forming method according to the first aspect, in forming the fore pile in front of the face along the cross section of the tunnel, a quick setting property using a hardening material and a hardening accelerator is used. Is formed in the ground, there is no danger that the uncured hardened material will flow out through the gap between the reinforcing steel pipe and the ground as in the conventional case, and the hardened material is injected into the ground from the injection nozzle. The hardened material is quickly solidified by the hardening accelerator, and the amount of unhardened hardened material that is discharged to the outside through the space between the reinforcing steel pipe and the injection pipe decreases with the formation of the solidified formation part. It will be.
[0044]
Therefore, as compared with the conventional method, the possibility that a cavity is formed between the upper portion of the fore pile and the ground due to excessive discharge of the mud during construction is eliminated, and the use of the hardening material is prevented by preventing wasteful outflow of the hardening material. It is possible to reduce the amount.
[0045]
Further, since the hardening material of the mud sucked from the mud suction port of the reinforcing steel pipe is thinned by the drilling water sprayed from the spray nozzle, the hardening material in the sludge solidifies with the hardening accelerator. There is no risk of clogging, the mud is discharged smoothly, and an efficient fore pile can be created.
[0046]
Similarly, according to the drilling device of claim 2, since the hardening material and the hardening accelerator are used to form the instantaneously solidified solidified portion in the ground, the solidified portion is formed through the gap between the reinforcing steel pipe and the ground. There is no danger of uncured hardened material flowing out, and the hardened material injected into the ground from the injection nozzle is quickly consolidated by the hardening accelerator, so the steel pipe for reinforcement and triple injection with the formation of the solidified formation part The amount of uncured hardened material discharged to the outside through the space between the tubes is also reduced.
[0047]
Therefore, it is possible to eliminate the possibility that a cavity is formed between the upper portion of the fore pile and the ground due to excessive sludge during the formation, and to reduce the use amount of the hardening material by preventing unnecessary outflow of the hardening material. Becomes possible.
[0048]
Also, even if the sludge is sucked from the sludge suction port of the reinforcing steel pipe, the hardening material is diluted by the drilling water sprayed from the injection nozzle, so that the hardening material in the sludge solidifies with the hardening accelerator. There is no risk of clogging, and the mud can be discharged smoothly.
[0049]
Furthermore, since the drilling device according to the present invention can be used by mounting it on a boom of an existing drilling machine, it has an advantage that it does not require any particular improvement of the existing drilling machine.
[Brief description of the drawings]
FIG. 1 is a sectional view of the ground when a fore pile is formed by a first embodiment of a drilling device according to claim 2;
FIG. 2 is a sectional view taken along line II-II of FIG.
FIG. 3 is a cross-sectional view of the ground showing a state in which a triple injection pipe is pulled out at the time of forming a fore pile.
FIG. 4 is a sectional view of a main part of a second embodiment of the drilling apparatus according to claim 2;
FIG. 5 is an explanatory view showing a conventional forpile forming method.
FIG. 6 is a cross-sectional view of a tunnel.
FIG. 7 is an explanatory view showing a construction method of a fore pile.
FIG. 8 is a cross-sectional view of a tunnel in which a lining body made of a fore pile is formed.
FIG. 9 is an explanatory view showing another conventional forpile forming method.
FIG. 10 is an explanatory view showing a state where a high-pressure injection pipe is pulled out of a reinforcing steel pipe.
FIG. 11 is a side view of a conventional drilling device.
[Explanation of symbols]
33 Reinforcing Steel Pipe 35 Ring Bit 37 Triple Injection Pipe 39 Inner Bit 41 Drilling Water Injection Hole 43 Drilling Water Injection Pipe 45 Hardening Material Supply Pipe 47 Hardening Acceleration Material Supply Pipe 55 Ground 57,61,73,81 Injection Nozzle 63, 65 Injection port 67 Solidification forming part 69 Drainage suction port 75 Drainage ports 77, 79 Drilling device G Hardening material G 'Hardening accelerator S Drainage W Drilling water

Claims

After inserting the injection pipe into the reinforcing steel pipe and projecting the inner bit attached to the tip of the injection pipe from the tip of the reinforcing steel pipe,
At the same time, the drilling water sent to the injection pipe is injected at a high pressure from the injection hole of the inner bit in the direction of travel, and the ground is cut while rotating and press-fitting it into the peripheral ground of the ground to be cut while moving it in the direction of pit opening. Drilling water is injected from the drilling water injection nozzle attached to the tip side of the injection pipe at high pressure to the rear of the steel pipe for reinforcement, and the suction force of the jet flows into the wastewater suction port provided in the steel pipe for reinforcement. Suction and discharge the soil from
After drilling the ground to a predetermined position,
Similarly, while rotationally press-fitting the reinforcing steel pipe and the injection pipe into the ground and injecting high-pressure drilling water from the inner bit, the hardening material and the hardening accelerator from each injection nozzle mounted on the tip side of the injection pipe, respectively. High-pressure injection is simultaneously performed to the side from the injection port provided in the reinforcing steel pipe to rapidly solidify and solidify the solidified formation by mixing the surrounding soil with the hardening material and the hardening accelerator. The mud is sucked from the mud suction port by the suction force of the drilling water jet, and diluted with the drilling water to prevent solidification and discharged.
After forming the solidified formation part to the predetermined position,
A fore pile forming method, wherein an injection pipe is pulled out and collected together with an inner bit, and a fore pile including a reinforcing steel pipe as a core material is formed in the ground.

A drilling bit is attached to the tip, a reinforcing steel pipe with a mud suction port and an injection port for hardening material, etc., opening in the peripheral wall on the tip side,
An inner bit is attached to the tip, a triple injection pipe inserted into the reinforcing steel pipe by projecting the inner bit from the tip of the reinforcing steel pipe,
A rotation drive mechanism for rotating the triple injection pipe and moving it in the front-back direction;
A rotational drive mechanism for rotating and moving the reinforcing steel pipe forward,
The triple injection tube is
A hardening material supply pipe equipped with an injection nozzle that injects high-pressure hardening material laterally from an injection port of the reinforcing steel pipe,
A hardening accelerator supply pipe equipped with an injection nozzle for injecting high-pressure hardening accelerator laterally from an injection port of the reinforcing steel pipe,
It consists of a drilling water injection pipe communicating with the drilling water injection hole provided in the inner bit,
The drilling water injection pipe is equipped with an injection nozzle that is installed on the inner bit side of the drainage suction port and that injects drilling water at a high pressure to the rear inside the reinforcing steel pipe. Drilling equipment.