JP2004239014A

JP2004239014A - Immersion method for pile and its device

Info

Publication number: JP2004239014A
Application number: JP2003032059A
Authority: JP
Inventors: Satoru Yamada; 悟山田
Original assignee: Nippon High Strength Concrete Co Ltd
Current assignee: Nippon High Strength Concrete Co Ltd
Priority date: 2003-02-10
Filing date: 2003-02-10
Publication date: 2004-08-26
Anticipated expiration: 2023-02-10
Also published as: JP4095461B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an immersion method for a pile and its device capable of making an amount of earth moving to the ground into almost zero without using a special pile having a fluid supply pipe in the thickness of a concrete pile. <P>SOLUTION: A friction cutter 110 and a cutter edge disc 60 closing an opening of the lower end of the pile is provided on the lower end of the pile 100, and an auger drill 40 consisting of an engaging section engaging with the disc 60, a spiral wing 41 and a driving section 30 giving rotation different from the pile and thrust force is inserted in a hollow hole of the pile, the pile 100 and the auger drill 40 are integrally rotated to drive the pile forward in the ground in a soft ground, and the auger drill 40 is preceded to perform a downward ground excavation from the lower end of the pile to make earth and sand only put in the pile 100 to consolidate it in the pile. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、直径３００〜１０００ｍｍ程度のコンクリート杭を地中に沈設する方法及びその装置に関し、さらに詳しくは、排出する排土量をほぼ零にするようにした技術に関する。
【０００２】
【従来の技術】
コンクリート基礎杭を地中に沈設する場合、杭の中空孔内にスパイラルオーガを挿入し、杭下端部の地層をスパイラルオーガで掘削し、排土しながら杭を沈下させることが、従来、通常行われている技術である。
【０００３】
この場合、スパイラルオーガで、杭の中空孔内の掘削土をすべて排出し、排出後に杭の中空孔を通ってセメントミルクを杭底に供給し、支持層と杭下端とを一体化する。このような従来の杭の沈設方法では、スパイラルオーガによって掘削する土砂をすべて地上に排出処理していた。近年、このような土木工事における排土等の廃棄処理場が枯渇し、排土の排出処理が問題となり、また、処理費用も高騰しつつある。
【０００４】
上記問題点を解決し、杭の沈設を容易にすると共に、掘削に伴う排土の量を極力削減し、排土処理費用の高騰を防止する技術開発が行われている。
【０００５】
例えば、まず、沈設すべきコンクリート杭の外径と一致する径のオーガドリルを用いて、杭の埋設深度まで地中を掘進し、オーガを逆転して掘削土を地上に排出しないようにオーガドリルを引上げ、一方、杭軸方向に貫通する注入孔を肉厚内に設けたコンクリート杭の下端に掘削用羽根を取付けておき、注入孔から圧力水又は泥水及び圧縮空気を注入しながらコンクリート杭をオーガ掘進跡に回転沈下させる技術がある（例えば、特許文献１参照。）。
【０００６】
この技術では、コンクリート杭として肉厚内を杭軸方向に貫通する注入孔を備えた杭を用い、注入孔の上端に流体供給管を連結し、注入孔を通って杭の下端に、圧縮空気、圧力水、泥水又はセメントミルクを供給する。
【０００７】
この技術では、杭の沈下によって排除される土砂は、泥土状となって杭の中空孔に進入し杭内を上昇してくるが、排除される土砂の大部分は杭の中空孔内に留まって圧密され、その一部のみが杭の上端から溢出する。従って、排土量が著しく減少し、排土処理費用が激減する。なお、泥土の一部は杭の外周面と地層との間に進入し、滑材の作用をなすので杭の沈下が容易になる。
【０００８】
また、プレストレストコンクリート杭の縦緊張材として中空ＰＣ鋼棒を用い、杭下端に掘削羽根を取付け、流体供給管に圧縮空気及び圧力水を供給して中空ＰＣ鋼棒内を通って杭下端から噴射させ、杭に回転力を付与して杭を地中に沈下させ、杭下端が支持層に到達後、セメントミルクを圧入しながら杭をさらに回転沈下させ、杭先端と支持層地盤と一体化させる技術がある（例えば、特許文献２参照。）。この技術は、プレストレストコンクリート杭の縦緊張材として中空ＰＣ鋼棒を用いる。
【０００９】
これらの従来技術では、杭の頭部に杭に回転力を与えるキャップを取付け、流体供給管から圧縮空気及び圧力水を供給して杭下端から噴射しつつ、杭に回転力を付与して杭を地中に沈下させる。圧縮空気及び圧力水は、杭下端の地層を柔弱化し、杭を回転させると掘削羽根は杭のコンクリート肉厚壁部分に相当する地層を攪拌し、杭の沈下を容易にする。
【００１０】
杭の沈下によって排除される土砂は、泥土状となって杭の中空孔に進入し、大部分は杭の中空部内に留まり、その一部が杭の上端から溢出する。
【００１１】
【特許文献１】
特開２００２−１９４７３２号公報（第２−４頁、図１）
【特許文献２】
特開２００２−９７６３９号公報（第２−４頁、図１）
【００１２】
【発明が解決しようとする課題】
本発明は上記従来技術のようなコンクリート杭の肉厚内に流体供給管を設けた特殊な杭を用いることなく、これらの技術よりもさらに排土量を少なくした、杭の沈設方法及び装置を提供することを目的とするものである。
【００１３】
【課題を解決するための手段】
本発明は、コンクリート杭を地中に沈設するに当たり、杭の下端外周にフリクションカッタを備えると共に杭の下端面を塞ぐ大きさでカッタ刃物を下面に装着した円板を備えておき、杭の中空孔内にオーガドリルを挿入し、該オーガドリルは前記円板を貫通して下端に掘削刃を備え、前記円板と係合する係合部を備え、杭内の下端近傍に長さ数ｍの螺旋羽根を備え、掘削刃近傍に開口する流体通路を軸内に内蔵し、かつ杭とは別の回転及び推力を付与可能としておき、軟質地盤では杭とオーガドリルを一体に回転させながら杭を地中に進入させ、硬質地盤では、オーガドリルに杭とは別の回転及び推力を付加して杭下端より下方の地盤掘削を行いつつ杭を地中に進入させることを特徴とする杭の沈設方法である。
【００１４】
本発明は、地上に排出する排土量を殆ど零とした杭の沈設方法を達成するものである。通常の軟質地盤では、杭先端に設けたカッタ刃物付き円板とフリクションカッタにより、地中を掘削しつつ地盤を圧密し、フリクションカッタにより杭周囲に隙間を設けて杭の沈下を容易にし、また、場合に応じて、高圧水、泥水及び圧縮空気のうち１又は複数をオーガドリルの軸に設けた流体通路を通って下端掘削部に噴出させて沈設を容易化させつつ杭を沈下させる。従って、排出土は全く生じない。
【００１５】
硬質地盤では、オーガドリルを先行させて掘削し、掘削泥土は杭中に進入させる。この泥土は、量が多ければ杭の上端から溢出するが、硬地盤でのみ穿孔掘削し、軟地盤では泥土を杭内に進入させないから、通常は、溢出する量は殆どない。従って、排土量を殆ど零か又は最小限に留めることが出来る。
【００１６】
本発明においても、従来と同様に、杭下端が支持層に到達した後、セメントミルクを支持層に加圧注入しながら杭をさらに沈下させ、杭下端近傍を支持層及び杭周囲の地盤と一体化させ、杭を固定する。この場合、流体通路はオーガドリルの軸内に設けられているから、杭の肉厚内に貫通孔を設けた杭を使用する必要はない。
【００１７】
上記本発明方法を好適に実施をすることが出来る本発明の装置は、コンクリート杭を回転沈下させる杭施工機と、該杭施工機とは別に杭内のオーガドリルに回転力及び推力を付与するオーガ駆動部とを備えたことを特徴とする杭の沈設装置である。
【００１８】
この装置では、杭下端面を塞ぐ大きさの円板カッタを備え、該円板カッタと係合する係合部をオーガドリルの先端近傍に設け、該係合部はオーガドリルを逆回転させると係合解除する結合構造とした。この円板カッタは、杭を回転沈下させる工程では掘削に寄与すると共に、杭下端の蓋として作用し、排土を杭の中空孔内に進入させない。オーガドリルを杭下端より下方に先行させて地盤を掘削する場合は、この円板カッタはオーガドリルと共に掘削に寄与すると共に、杭の下端面から離脱して杭の中空孔を開口させ、杭の中空孔内に泥土を誘導する。従って、掘削能力拡大に貢献し、杭の沈下を容易にする。
【００１９】
誘導された泥土は圧密されながら杭内のオーガドリルの螺旋羽根により杭の中空孔内を上昇する。螺旋羽根は長さ数ｍとし、中空孔内に進入した泥土を圧密し、積極的に排土する作用を減殺している。
【００２０】
杭を支持層に設定した後は、円板カッタはオーガドリルから離脱させて杭先端部地中に残置する。
【００２１】
また、オーガドリル軸に、オーガドリルの先端に設けた噴射ノズルに連通する流体通路を内蔵した。この噴射ノズルは、泥水、高圧水、圧縮空気、セメントミルクなどの噴出口として活用することが出来る。
【００２２】
【発明の実施の形態】
以下図面を参照して本発明の実施の形態を説明する。
【００２３】
図１は本発明方法の実施工程を示す杭の沈設装置１を示すものである。この沈設装置１はコンクリート杭１００を回転沈下させる杭施工機１０と、コンクリート杭１００内に挿入したオーガドリル４０に回転力を与える旋回駆動部３１とオーガドリル４０を下方に押す推力を付与するジャッキ３２とからなるオーガ駆動部３０を、吊り下げ装置１１に取り付けている。杭施工機１０は、コンクリート杭１００の頭部に取付装置２０を介して結合される。
【００２４】
コンクリート杭１００は、下端部にフリクションカッタ１１０を装着している。フリクションカッタ１１０は、杭の下端部外周に、外周から垂下するように取り付けられた複数枚の円弧板状のカッタであって、杭を回転させると、杭の下端より下方の地盤中に杭の外径より少し大きいリング状の空所を形成し、杭の外周に隙間を生ずるので、杭と地盤との摩擦をなくし、杭の沈下を容易にさせるカッタである。
【００２５】
また、コンクリート杭１００の下端の開口を塞ぐ円板６０を備え、この円板６０は下面に掘削刃物６１を装着している。この円板６０は杭１００に取り付けられているのではなく、後述のようにオーガドリル軸に係合している。
【００２６】
コンクリート杭１００の中空孔内に挿入されているオーガドリル４０は、頂部をオーガドリル駆動部３０に結合され、下端に掘削刃物５０を備える。また、先端近傍に軸に直角に突出する突出腕４２、４３を備え、この突出腕４２が円板６０に係着する。オーガドリル４０が正回転の時、円板６０がオーガ軸と一体になって回転する。このとき円板６０は、突出腕４２を介してオーガドリル４０の軸方向推力を受けると共に、突出腕４３を介して回転力を受け、地盤の切削に寄与する。オーガドリル４０を逆回転すると、突出腕４３が円板６０とオーガドリル４０との係合が解除され、円板６０は地中に残置される。
【００２７】
杭下端面を塞ぐ大きさの円板６０を取付け、この円板６０はオーガドリルを逆回転させてオーガドリル軸から離脱する結合機構を備えている。
【００２８】
オーガドリル４０は、螺旋羽根４１を装着している。この螺旋羽根４１は、オーガドリルの先端側のコンクリート杭中空部内に長さ数ｍ、例えば５ｍ程度取り付けられている。
【００２９】
また、オーガドリル４０は軸が二重管構造となっており、流体通路を形成している。そして、オーガドリル４０の先端の掘削刃物５０の近傍に、噴射ノズル５１を備えている。
【００３０】
本発明方法は、軟質地盤では杭１００とオーガドリル４０を一体に軸周りに回転させながら杭１００を地中に進入させ、硬質地盤では、オーガドリル４０に杭１００とは別の回転及び推力を付加して杭下端より下方の地盤掘削を行って杭１００を進入させる。
【００３１】
軟質地盤では、円板６０が杭底の開口を塞いでおり、杭と一体となって掘削沈下するので排土を生じない。硬質地盤の場合にのみ円板６０が杭の下端から杭内に排土を導入する。従って、全体として排土は著しく減少し、地上に排出する量は殆ど零となる。
【００３２】
上記杭施工機１０とコンクリート杭１００の頭部とを結合する取付装置２０について図２を参照して説明する。図２では、杭駆動装置１０の下部フランジ１２と取付装置２０の上部フランジ２５とを離して示しているが、実際は結合されている。取付装置２０は、短管２１の下部に係止部材２３を備えている。コンクリート杭１００の頂部スリーブ１０７に係止角棒１０８を溶接にて取付け、この係止角棒１０８に係止部材２３を係止させる。係止部材２３は、入り組んだ切欠２２を備え、切欠２２は係止角棒１０８を係止し、駆動装置１０が正回転するとき係止角棒１０８を介して回転トルクを杭１００に伝達し、逆方向に回転すると、杭１００との係止を解除する形状となっている。短管２１に設けられている窓２４は杭１００内を上昇してきた排土が杭内に収納しきれなくなった場合に溢出させる排出口である。
【００３３】
図３は円板６０を説明する説明図で、杭１００の下方から見た図である。円板６０は、杭１００の下端の中空孔開口を塞ぐ円板であって、底面に刃物６１を装着している。中心に、オーガドリルの軸４４が通る孔６２が設けられており、この孔６２の周囲に、点対称に一対の切欠６３が設けられている。オーガドリルの軸４４から突出した腕４３はこの切欠６３を通って円板６０の下側に位置し、その位置で回動し、刃物６１の背面に当接している。オーガドリルの軸４４から突出したもう一つの腕４２は、切欠６３を通らない大きさに形成されており、円板６０の上面に当接し、オーガドリル４０が円板６０を押下げるとき作用する。オーガドリル４０が正回転するとき、円板６０をオーガドリル４０と一体に回転させ、切削を行う。オーガドリル４０が逆回転すると、腕４３は切欠６３を通って上方に抜け出すことができ、円板６０とオーガドリル４０の係合が解除される。
【００３４】
オーガドリル４０の軸４４は二重管となっており、同時に２種類の流体を杭先端地中に供給することができる。例えば、二重管が形成する通路のうち、外側を圧縮空気の通路、内側を圧力水、泥水又はセメントミルクの通路とすればよい。
【００３５】
本発明の杭の沈下工程は次の通りである。
【００３６】
掘削地盤が軟弱地盤の場合は、カッタ刃物円板６０が杭１００の先端部を開口を塞いだ状態で、杭１００とオーガドリル４０とカッタ刃物円板６０を一体に回転させ、杭１００を地盤中に沈下させる。このとき、オーガドリル４０の先端刃物５０、円板６０の切削刃物６１が杭１００と共に回転して地盤を掘削し、杭１００のフリクションカッタ１１０が杭１００の周縁を案内するリング状の空洞を形成するので、杭１００は掘削地盤を圧密しながら沈下する。
【００３７】
この沈下のときに、オーガドリル４０の先端部から圧縮空気及び圧力水を供給し、これを杭１００下端から噴射しながら杭１００に回転力を付与して杭を地中に沈下させると好適である。圧縮空気の圧力は０．７ＭＰａ（７ｋｇｆ／ｃｍ^２）以上、圧力水の圧力は１０ＭＰａ（１００ｋｇｆ／ｃｍ^２）以上とするとよい。
【００３８】
施工地盤が軟質地盤の場合は、円板６０が杭下端の開口を閉塞した状態で杭を沈設するので、排土を生ずることはなく、地盤を圧密状態とすることができ、杭の支持力機構上有利となる。
【００３９】
杭１００の下端が硬質地盤に到達して杭１００の沈設が至難となってきた状態で、オーガドリル４０にオーガ駆動部３０から杭１００とは別に、図４に示すように、推力１０２及び回転１０３を与え、掘削用カッタ刃物円板６０を杭１００の下端から離反させて下方に先行させ、オーガドリル４０の切削先端刃物５０、円板６０の下面の切削刃物６１を杭の下端から先行させて地盤の掘削を行う。このとき、高圧水や圧縮空気の噴出１０４を行う。そして掘削土をオーガドリル４０の先行掘削部から杭１００の中空孔内に矢印１０５で示すように導入し、オーガドリル４０の螺旋羽根４１によって上方に押し上げながら、杭１００を沈設させる。杭中空部に掘削土が堆積することになる。
【００４０】
硬質地盤においては、カッタ刃物円板６０を杭１００の下端から離反させ地盤の掘削を先行させ、スパイラルオーガ４０によって掘削土砂を上方に押し上げることができるので、硬質地盤においても、杭１００の沈設が円滑である。
【００４１】
泥状化した排出土は杭１００の中空孔内を上昇するが、大部分は杭１００内に留まり、余剰の分のみ杭１００の頭部から溢出して排出する。従って、スパイラルオーガを杭の中空部に挿入して杭の中空部の全断面を掘削し排土をすべて杭外に排出する従来の技術と比較して、排土量は著しく減少する。また杭１００の外面を上昇する泥状化した排土や圧縮空気は、杭と地層との摩擦を低減し、杭の沈下を容易にする。なお、掘削抵抗が大きい場合には、高圧水に加え圧縮空気を同時に噴出させながら、掘削を行う。
【００４２】
図５は、再び軟質地盤に到達したとき、オーガドリル４０の推力を解除し、独自の回転を止め、杭１００と一体化させて杭１００の回転１０１による沈下を進める工程を示している。
【００４３】
図６は別の実施例の杭１００の下端部の詳細を示す縦断面図で、軟弱地盤中で杭を沈下させている状態を示し、図７はその底面図である。また、図８は図６の実施例の硬質地盤中における沈下工程を示す図である。図９は、図８の円板６０の上面図である。図６、図８ではオーガドリル４０の二重管及び噴射ノズル５１、５２及びその噴射５３、５４を詳細に示している。
【００４４】
また、オーガドリル４０の軸から突出している腕４５は、図１で示した２個の腕４２、４３に代わり１個となっており、円板６０にハウジング６６を設け、ハウジング６６内にストッパ６７を設け、円板６０の下面とハウジング６６の底面が、腕４５の上下の移動を規制するようになっている。円板６０とオーガドリル４０との結合方式は、図１の方式でも図６の方式でもよく、またその他の形式でもよく、この形式は問わない。要はオーガドリル４０の正回転のとき、オーガドリル４０と円板６０とが一体に作動し、オーガドリル４０の逆回転のとき両者の係合が容易に解除されさえすればよい。図９において、腕４５が円板６０の切欠６５を通って係着する機構は、図３に示した腕４３と切欠６３の関係と同様である。
【００４５】
前述の従来工法においては、杭中空部を通して掘削土砂を上方に搬送する手段を採用しているので、地盤状況によって掘削土が地上に排出される場合があったが、本発明方法ではオーガドリルの上下によって杭先端部を自由に開閉させ、沈下が困難な硬質地盤の時だけ排土を杭内に誘導するようにコントロールすることができるので、地上への土砂の排出量をなくするか、又は著しく減少させることができる。
【００４６】
また、従来工法では、杭製造時において杭壁厚中にパイプ又は穴あきＰＣ鋼棒を埋込んで置く必要があり、杭は特別受注生産によらなければならなかったが、本発明方法ではこれを必要とせず、既存杭を使用することができる。
【００４７】
杭の沈設能率は、従来工法の杭に回転を与えて摩擦力を低減する手段に加えて、杭先端地盤をカッタ刃物円板を用いて掘削することを併用しているので、従来よりも掘削効率が向上する。
【００４８】
杭下端が支持層に到達したら、圧縮空気と圧力水の供給を止め、流体通路を通って根固め液としてセメントミルクを注入しながら杭を回転沈下させる。セメントミルクの濃度は水セメント比で概ね６０％程度が好適である。このときセメントミルクは杭下端の支持層を固化させると共に、杭の外周部の隙間内も上昇して支持層と杭との一体化に寄与する。
【００４９】
支持層中に杭先端を埋設後、カッタ刃物円板６０を杭先端部に当接させ、杭１００の先端部を閉塞した状態とし、杭に回転を与えながら二重管構造のオーガドリルの心管から根固め液を１００ｋｇ／ｃｍ^２以上の高圧で噴射し、杭下方の地盤及びフリクションカッタ間を通して、杭外周面にセメントミルクを充填させる。
【００５０】
根固め液及び杭周固定液には、膨張材を添加したセメントミルクを使用することによって、根固めを強固にし、杭周面摩擦力度を向上させることができる。
【００５１】
根固め液及び杭周固定液の注入が完了すると、支持層地盤と杭先端が一体化したセメントミルク硬化体が形成され、支持力を発現させる。オーガドリルを逆回転させて、カッタ刃物円板６０からオーガドリル４０を抜き取り、逆回転の状態でオーガドリルを完全に引抜く。そして杭上端の治具を取り外し、杭施工を完了する。
【００５２】
本発明は、従来工法と比べ、根固め液及び杭周固定液のセメントミルク注入は、杭先端部を閉塞した状態で可能であり、注入効率が高い。
【００５３】
【発明の効果】
本発明によれば、肉厚内に流体供給管を設けた特殊なコンクリート杭を用いることなく、地上への排土量を殆ど零にした、杭の沈設方法を実現することができた。
【図面の簡単な説明】
【図１】本発明の実施例の装置の説明図である。
【図２】実施例の部分図である。
【図３】円板の説明図である。
【図４】沈下工程の説明図である。
【図５】沈下工程の説明図である。
【図６】別の実施例の杭下端部の縦断面図である。
【図７】図６の底面図である。
【図８】図６の実施例の沈下工程の縦断面図である。
【図９】円板の上面図である。
【符号の説明】
１杭の沈設装置
１０杭施工機
１０杭駆動装置
１１吊り下げ装置
１２下部フランジ
２０取付装置
２１短管
２２切欠
２３係止部材
２４窓
２５上部フランジ
３０オーガ駆動部
３１旋回駆動部
３２ジャッキ
４０オーガドリル
４１螺旋羽根
４２、４３腕
４４オーガドリルの軸
４５腕
５０掘削刃物
５１、５２噴射ノズル
５３、５４噴射
６０円板
６１切削刃物
６２孔
６３切欠
６５切欠
６６ハウジング
６７ストッパ
１００コンクリート杭
１０１回転
１０２推力
１０３回転
１０５矢印
１０７頂部スリーブ
１０８係止角棒
１１０フリクションカッタ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for laying a concrete pile having a diameter of about 300 to 1000 mm in the ground, and more particularly to a technique for reducing the amount of discharged soil to substantially zero.
[0002]
[Prior art]
Conventionally, when laying a concrete foundation pile in the ground, it is usual to insert a spiral auger into the hollow hole of the pile, excavate the stratum at the bottom of the pile with a spiral auger, and settle the pile while discharging the soil. Technology.
[0003]
In this case, all the excavated soil in the hollow hole of the pile is discharged by the spiral auger, and after discharge, cement milk is supplied to the pile bottom through the hollow hole of the pile to integrate the support layer and the lower end of the pile. In such a conventional pile laying method, all the earth and sand excavated by the spiral auger is discharged to the ground. In recent years, waste disposal sites such as earth removal in such civil engineering work have been depleted, and disposal of the earth removal has become a problem, and the disposal cost has been rising.
[0004]
Technical developments have been made to solve the above problems, to facilitate the laying of piles, to reduce the amount of earth removal accompanying excavation as much as possible, and to prevent a rise in earth removal processing costs.
[0005]
For example, first, using an auger drill having the same diameter as the outer diameter of the concrete pile to be laid, dig into the ground to the burial depth of the pile, and reverse the auger to prevent the excavated soil from discharging to the ground. On the other hand, drilling wings are attached to the lower end of the concrete pile having an injection hole penetrating in the pile axis direction in the thickness, and the concrete pile is injected while injecting compressed water or muddy water and compressed air from the injection hole. There is a technique of rotating and sinking at the auger track (for example, see Patent Document 1).
[0006]
In this technology, a pile with an injection hole that penetrates through the thickness in the axial direction of the pile is used as a concrete pile, a fluid supply pipe is connected to the upper end of the injection hole, and compressed air is passed through the injection hole to the lower end of the pile. Supply pressure water, muddy water or cement milk.
[0007]
In this technology, the sediment removed by the settlement of the pile becomes muddy and enters the hollow hole of the pile and rises in the pile, but most of the removed soil remains in the hollow hole of the pile. And only a part of it spills out of the top of the pile. Therefore, the amount of earth removal is remarkably reduced, and the earth removal processing cost is drastically reduced. A part of the mud enters between the outer peripheral surface of the pile and the stratum and acts as a sliding material, so that the pile is easily settled.
[0008]
In addition, a hollow PC steel rod is used as a longitudinal tendon for the prestressed concrete pile, a drilling blade is attached to the lower end of the pile, compressed air and pressure water are supplied to the fluid supply pipe, and the air is injected from the lower end of the pile through the hollow PC steel rod. Then, the pile is settled in the ground by applying a rotational force to the pile, and after the bottom end of the pile reaches the support layer, the pile is further rotated and settled while pressuring cement milk, and integrated with the pile tip and the support layer ground There is a technology (for example, refer to Patent Document 2). This technique uses hollow PC steel bars as longitudinal tendons for prestressed concrete piles.
[0009]
In these prior arts, a cap that gives a rotational force to a pile is attached to the head of the pile, and compressed air and pressure water are supplied from a fluid supply pipe and jetted from a lower end of the pile, and a rotational force is applied to the pile to apply a rotational force to the pile. Sink into the ground. The compressed air and the pressurized water soften the stratum at the bottom of the pile, and when the pile is rotated, the excavating blades agitate the stratum corresponding to the concrete thick wall portion of the pile and facilitate the settlement of the pile.
[0010]
The sediment removed by the settlement of the pile becomes muddy and enters the hollow hole of the pile, most of which stays in the hollow part of the pile, and a part thereof overflows from the upper end of the pile.
[0011]
[Patent Document 1]
JP-A-2002-194732 (pages 2-4, FIG. 1)
[Patent Document 2]
JP-A-2002-97639 (pages 2-4, FIG. 1)
[0012]
[Problems to be solved by the invention]
The present invention does not use a special pile having a fluid supply pipe in the thickness of a concrete pile as in the above-described conventional technique, and further reduces the amount of soil removal compared to these techniques, thereby providing a pile setting method and apparatus. It is intended to provide.
[0013]
[Means for Solving the Problems]
According to the present invention, when laying a concrete pile in the ground, it is provided with a friction cutter provided on the outer periphery of the lower end of the pile and a disk having a cutter blade attached to the lower surface with a size sufficient to cover the lower end face of the pile, and the hollow of the pile is provided. An auger drill is inserted into the hole, the auger drill penetrates the disc, has a cutting edge at the lower end, has an engaging portion for engaging with the disc, and has a length of several meters near the lower end in the pile. The spiral blade is provided inside the shaft, and a fluid passage opening near the excavation blade is built in the shaft, and it is possible to apply a different rotation and thrust to the pile.In soft ground, the pile and the auger drill are rotated integrally and piled. In the hard ground, piles are characterized by adding a different rotation and thrust to the auger drill and excavating the ground below the lower end of the pile while advancing the pile into the ground. It is a sinking method.
[0014]
The present invention achieves a method of laying a pile with almost no soil discharge to the ground. In ordinary soft ground, a disc with a cutter blade and a friction cutter provided at the tip of the pile are used to consolidate the ground while excavating the ground, and a gap is provided around the pile with the friction cutter to facilitate settlement of the pile, In some cases, one or more of high-pressure water, muddy water and compressed air are ejected to a lower excavation part through a fluid passage provided in the auger drill shaft, and the pile is settled while facilitating settlement. Therefore, no discharged soil is generated.
[0015]
In hard ground, drilling is performed with an auger drill ahead, and drilling mud enters the pile. If the amount of the mud is large, it overflows from the upper end of the pile. However, since the drilling and excavation is performed only on the hard ground and the mud does not enter the pile on the soft ground, the amount of the mud usually overflows little. Therefore, the amount of earth removal can be almost zero or minimized.
[0016]
In the present invention, similarly to the related art, after the lower end of the pile reaches the support layer, the pile is further settled while cement milk is injected into the support layer under pressure, and the lower end of the pile is integrated with the support layer and the ground around the pile. And fix the pile. In this case, since the fluid passage is provided in the shaft of the auger drill, it is not necessary to use a pile provided with a through hole in the thickness of the pile.
[0017]
The apparatus of the present invention that can suitably carry out the above-described method of the present invention provides a pile construction machine that rotates and sinks a concrete pile, and imparts rotational force and thrust to an auger drill in the pile separately from the pile construction machine. A pile setting device, comprising: an auger driving unit.
[0018]
In this device, a disk cutter having a size to close the lower end surface of the pile is provided, and an engaging portion that engages with the disk cutter is provided near the tip of the auger drill, and the engaging portion rotates the auger drill in a reverse direction. A coupling structure for releasing the engagement was adopted. The disc cutter contributes to excavation in the process of rotating and sinking the pile, and also acts as a lid at the lower end of the pile, and does not allow the earth to be discharged into the hollow hole of the pile. When excavating the ground with the auger drill preceding the lower end of the pile, this disk cutter contributes to the excavation together with the auger drill, separates from the lower end surface of the pile and opens the hollow hole of the pile, Induce mud in the hollow hole. Therefore, it contributes to the excavation capacity expansion and facilitates the settlement of the pile.
[0019]
The induced mud rises in the hollow hole of the pile by the spiral blade of the auger drill in the pile while being compacted. The spiral blade has a length of several meters, and consolidates the mud that has entered the hollow hole to reduce the effect of actively discharging the soil.
[0020]
After setting the pile as the support layer, the disk cutter is detached from the auger drill and left in the ground at the tip of the pile.
[0021]
Further, the auger drill shaft has a built-in fluid passage communicating with the injection nozzle provided at the tip of the auger drill. This injection nozzle can be used as an outlet for muddy water, high-pressure water, compressed air, cement milk, and the like.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows a pile setting device 1 showing the steps of the method of the present invention. The submerging device 1 includes a pile construction machine 10 that rotates and sinks a concrete pile 100, a turning drive unit 31 that applies a rotational force to an auger drill 40 inserted into the concrete pile 100, and a jack that applies a thrust to push the auger drill 40 downward. An auger drive unit 32 including the auger drive unit 32 is attached to the suspension device 11. The pile construction machine 10 is connected to the head of the concrete pile 100 via a mounting device 20.
[0024]
The concrete pile 100 has a friction cutter 110 attached to the lower end. The friction cutter 110 is a plurality of circular plate-shaped cutters attached to the outer periphery of the lower end portion of the pile so as to hang down from the outer periphery. When the pile is rotated, the pile cutter is placed in the ground below the lower end of the pile. A cutter that forms a ring-shaped void slightly larger than the outer diameter and creates a gap around the periphery of the pile, eliminates friction between the pile and the ground, and facilitates settlement of the pile.
[0025]
Further, the concrete pile 100 is provided with a disc 60 for closing the opening at the lower end, and the disc 60 has a cutting tool 61 mounted on the lower surface thereof. The disk 60 is not attached to the pile 100 but is engaged with an auger drill shaft as described later.
[0026]
The auger drill 40 inserted into the hollow hole of the concrete pile 100 has a top coupled to the auger drill drive unit 30 and has a drilling blade 50 at a lower end. Further, protruding arms 42 and 43 protruding at right angles to the axis are provided near the distal end, and the protruding arms 42 are engaged with the disk 60. When the auger drill 40 rotates forward, the disk 60 rotates integrally with the auger shaft. At this time, the disc 60 receives the axial thrust of the auger drill 40 via the protruding arm 42 and receives the rotational force via the protruding arm 43 to contribute to the cutting of the ground. When the auger drill 40 is rotated in the reverse direction, the protrusion arm 43 disengages the disc 60 from the auger drill 40, and the disc 60 is left underground.
[0027]
A disc 60 having a size to close the lower end surface of the pile is attached, and the disc 60 is provided with a coupling mechanism for rotating the auger drill in the reverse direction and separating from the auger drill shaft.
[0028]
The auger drill 40 has a spiral blade 41 mounted thereon. The spiral blade 41 is attached to the distal end side of the auger drill in the hollow portion of the concrete pile, for example, about several meters in length, for example, about 5 m.
[0029]
The auger drill 40 has a double-pipe structure with a shaft, and forms a fluid passage. In addition, an injection nozzle 51 is provided near the excavation blade 50 at the tip of the auger drill 40.
[0030]
The method of the present invention allows the pile 100 to penetrate into the ground while rotating the pile 100 and the auger drill 40 integrally around the axis in soft ground, and to apply a different rotation and thrust to the auger drill 40 from the pile 100 in hard ground. In addition, the ground excavation below the lower end of the pile is performed to allow the pile 100 to enter.
[0031]
In the soft ground, the disk 60 closes the opening at the bottom of the pile, and excavates and sinks together with the pile, so that no earth discharging occurs. Only in the case of hard ground, the disc 60 introduces earth removal from the lower end of the pile into the pile. Therefore, the total amount of earth removal is significantly reduced, and the amount discharged to the ground is almost zero.
[0032]
A mounting device 20 for connecting the pile construction machine 10 and the head of the concrete pile 100 will be described with reference to FIG. Although the lower flange 12 of the pile driving device 10 and the upper flange 25 of the mounting device 20 are shown separately in FIG. 2, they are actually connected. The attachment device 20 includes a locking member 23 below the short pipe 21. The locking square bar 108 is attached to the top sleeve 107 of the concrete pile 100 by welding, and the locking member 23 is locked to the locking square bar 108. The locking member 23 has a complicated notch 22, which locks the locking square bar 108, and transmits the rotation torque to the pile 100 via the locking square bar 108 when the driving device 10 rotates forward. , When it is rotated in the opposite direction, the lock with the pile 100 is released. The window 24 provided in the short pipe 21 is a discharge port that overflows when the soil discharged from the pile 100 cannot be stored in the pile.
[0033]
FIG. 3 is an explanatory diagram for explaining the disk 60, as viewed from below the pile 100. The disk 60 is a disk that closes the opening of the hollow hole at the lower end of the pile 100, and has a cutting tool 61 attached to the bottom surface. A hole 62 through which the shaft 44 of the auger drill passes is provided at the center, and a pair of notches 63 are provided around the hole 62 symmetrically with respect to a point. The arm 43 protruding from the auger drill shaft 44 is located below the disc 60 through the notch 63, rotates at that position, and contacts the back surface of the blade 61. The other arm 42 protruding from the auger drill shaft 44 is formed so as not to pass through the notch 63, abuts on the upper surface of the disc 60, and acts when the auger drill 40 pushes down the disc 60. . When the auger drill 40 rotates forward, the disk 60 is rotated integrally with the auger drill 40 to perform cutting. When the auger drill 40 rotates in the reverse direction, the arm 43 can escape upward through the notch 63, and the engagement between the disc 60 and the auger drill 40 is released.
[0034]
The shaft 44 of the auger drill 40 is a double tube, and can simultaneously supply two types of fluids to the pile tip underground. For example, among the passages formed by the double pipe, the outside may be a passage for compressed air, and the inside may be a passage for pressurized water, muddy water or cement milk.
[0035]
The pile sinking process of the present invention is as follows.
[0036]
When the excavated ground is soft ground, the pile 100, the auger drill 40, and the cutter blade disk 60 are integrally rotated with the cutter blade disk 60 closing the opening of the tip of the pile 100, and the pile 100 is ground. Settle in. At this time, the tip blade 50 of the auger drill 40 and the cutting blade 61 of the disk 60 rotate together with the pile 100 to excavate the ground, and the friction cutter 110 of the pile 100 forms a ring-shaped cavity for guiding the periphery of the pile 100. Therefore, the pile 100 sinks while consolidating the excavated ground.
[0037]
At the time of subsidence, it is preferable to supply compressed air and pressure water from the tip of the auger drill 40, apply a rotational force to the pile 100 while injecting the jet from the lower end of the pile 100, and submerge the pile into the ground. is there. The pressure of the compressed air is preferably 0.7 MPa (7 kgf / cm ² ) or more, and the pressure of the pressurized water is preferably 10 MPa (100 kgf / cm ² ) or more.
[0038]
When the construction ground is soft ground, the pile is laid down with the disk 60 closing the opening at the lower end of the pile, so that no soil is discharged and the ground can be brought into a compacted state, and the bearing capacity of the pile This is mechanically advantageous.
[0039]
In a state where the lower end of the pile 100 has reached the hard ground and the subsidence of the pile 100 has become difficult, the thrust 102 and the rotation of the auger drill 40 as shown in FIG. 103, the excavating cutter blade disk 60 is moved away from the lower end of the pile 100 to move downward, and the cutting tip blade 50 of the auger drill 40 and the cutting blade 61 on the lower surface of the disk 60 move forward from the lower end of the pile. To excavate the ground. At this time, high-pressure water or compressed air is ejected 104. Then, the excavated soil is introduced from the preceding excavation part of the auger drill 40 into the hollow hole of the pile 100 as indicated by an arrow 105, and the pile 100 is laid down while being pushed upward by the spiral blades 41 of the auger drill 40. Excavated soil will accumulate in the hollow part of the pile.
[0040]
In the hard ground, the cutter blade disk 60 is moved away from the lower end of the pile 100 to advance the excavation of the ground, and the excavated earth and sand can be pushed upward by the spiral auger 40. It is smooth.
[0041]
Although the muddy discharged soil rises in the hollow hole of the pile 100, most of the soil remains in the pile 100, and only the surplus portion overflows from the head of the pile 100 and is discharged. Therefore, compared with the conventional technique of inserting a spiral auger into the hollow portion of the pile, excavating the entire cross section of the hollow portion of the pile, and discharging all the soil to the outside of the pile, the amount of soil removal is significantly reduced. Moreover, the muddy soil and compressed air that rises on the outer surface of the pile 100 reduce friction between the pile and the stratum and facilitate the settlement of the pile. If the excavation resistance is high, excavation is performed while simultaneously blowing compressed air in addition to high-pressure water.
[0042]
FIG. 5 shows a step of releasing the thrust of the auger drill 40 when stopping on the soft ground again, stopping its own rotation, integrating the pile 100 with the pile 100, and advancing the settlement by the rotation 101 of the pile 100.
[0043]
FIG. 6 is a longitudinal sectional view showing the details of the lower end of the pile 100 of another embodiment, showing a state where the pile is submerged in soft ground, and FIG. 7 is a bottom view thereof. FIG. 8 is a view showing a subsidence process in the hard ground of the embodiment of FIG. FIG. 9 is a top view of the disk 60 of FIG. 6 and 8, the double pipe of the auger drill 40, the injection nozzles 51 and 52, and the injections 53 and 54 thereof are shown in detail.
[0044]
The arm 45 protruding from the shaft of the auger drill 40 is replaced by a single arm instead of the two arms 42 and 43 shown in FIG. The lower surface of the disk 60 and the lower surface of the housing 66 regulate the vertical movement of the arm 45. The method of connecting the disc 60 and the auger drill 40 may be the method shown in FIG. 1 or the method shown in FIG. 6, or may be another type, and this type is not limited. In short, the auger drill 40 and the disk 60 only need to be operated integrally when the auger drill 40 rotates forward, and the engagement between the two can be easily released when the auger drill 40 rotates backward. 9, the mechanism by which the arm 45 is engaged through the notch 65 of the disk 60 is the same as the relationship between the arm 43 and the notch 63 shown in FIG.
[0045]
In the above-mentioned conventional method, since the means for transporting the excavated soil upward through the hollow portion of the pile is employed, the excavated soil may be discharged to the ground depending on the ground condition. The tip of the pile can be freely opened and closed by up and down, and it can be controlled to guide soil removal only in hard ground where settlement is difficult, so that the amount of earth and sand discharged to the ground is eliminated, or It can be significantly reduced.
[0046]
Also, in the conventional method, it was necessary to embed a pipe or a perforated PC steel rod in the pile wall thickness during pile production, and the pile had to be produced by special order production. Instead, existing piles can be used.
[0047]
The pile sinking efficiency is improved by excavating the pile tip ground using a cutter blade disk in addition to the method of reducing the frictional force by rotating the pile in the conventional method. Efficiency is improved.
[0048]
When the lower end of the pile reaches the support layer, the supply of compressed air and pressurized water is stopped, and the pile is spun down while cement milk is injected as a consolidation liquid through a fluid passage. The concentration of the cement milk is preferably about 60% in terms of water cement. At this time, the cement milk solidifies the support layer at the lower end of the pile and also rises in the gap at the outer peripheral portion of the pile to contribute to the integration of the support layer and the pile.
[0049]
After the tip of the pile is buried in the support layer, the cutter blade disk 60 is brought into contact with the tip of the pile, the tip of the pile 100 is closed, and the core of the auger drill having the double pipe structure is given while rotating the pile. The root compaction liquid is injected from the pipe at a high pressure of 100 kg / cm ² or more, and the cement milk is filled on the outer peripheral surface of the pile through the space below the pile and between the friction cutters.
[0050]
By using cement milk to which an expanding material is added as the root compaction liquid and the pile peripheral fixation liquid, the root compaction can be strengthened and the pile peripheral surface frictional force can be improved.
[0051]
Upon completion of the injection of the root compaction liquid and the pile fixation liquid, a hardened cement milk body in which the ground of the support layer and the tip of the pile are integrated is formed, and the support force is developed. By rotating the auger drill in the reverse direction, the auger drill 40 is extracted from the cutter blade disc 60, and the auger drill is completely pulled out in the reverse rotation state. Then, the jig at the top of the pile is removed to complete the pile construction.
[0052]
According to the present invention, the cement milk can be injected with the root compaction liquid and the pile fixation liquid in a state where the tip of the pile is closed, and the injection efficiency is higher than in the conventional method.
[0053]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, without using the special concrete pile in which the fluid supply pipe was provided in the thickness, the pile settling method which made the amount of earth removal on the ground almost zero was realizable.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an apparatus according to an embodiment of the present invention.
FIG. 2 is a partial view of the embodiment.
FIG. 3 is an explanatory diagram of a disk.
FIG. 4 is an explanatory view of a settlement step.
FIG. 5 is an explanatory view of a settlement step.
FIG. 6 is a longitudinal sectional view of a lower end portion of a pile according to another embodiment.
FIG. 7 is a bottom view of FIG. 6;
FIG. 8 is a longitudinal sectional view of a settlement step of the embodiment of FIG. 6;
FIG. 9 is a top view of the disk.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pile setting device 10 Pile construction machine 10 Pile drive device 11 Hanging device 12 Lower flange 20 Mounting device 21 Short pipe 22 Notch 23 Locking member 24 Window 25 Upper flange 30 Auger drive unit 31 Swivel drive unit 32 Jack 40 Auger drill 41 Spiral blade 42, 43 Arm 44 Auger drill shaft 45 Arm 50 Drilling knife 51, 52 Injection nozzle 53, 54 Injection 60 Disk 61 Cutting knife 62 Hole 63 Notch 65 Notch 66 Housing 67 Stopper 100 Concrete pile 101 Rotation 102 Thrust 103 Rotation 105 Arrow 107 Top sleeve 108 Locking square bar 110 Friction cutter

Claims

When laying a concrete pile in the ground, a friction cutter is provided around the lower end of the pile and a disk with a cutter blade is attached to the lower surface of a size that closes the lower end of the pile. A drill is inserted, the auger drill includes a drilling blade at the lower end that penetrates the disk, includes an engaging portion that engages with the disk, and a spiral blade having a length of several meters near the lower end in the pile. A fluid passage opening near the excavation blade is built in the shaft, and it is possible to apply rotation and thrust different from the pile, and in soft ground, the pile and the auger drill are rotated together and the pile is buried in the ground. A method of laying a pile, wherein the pile is penetrated into the ground while applying a different rotation and thrust to the auger drill on hard ground to excavate the ground below the lower end of the pile.

The method according to claim 1, wherein one or more of high-pressure water, muddy water and compressed air are ejected to a pile bottom excavation part via the fluid passage.

After the lower end of the pile reaches the support layer, the pile is further settled while cement milk is injected into the support layer through the fluid passage under pressure, and the vicinity of the lower end of the pile is integrated with the support layer and the ground around the pile. 3. The method according to claim 1 or 2, wherein the pile is laid down.

A pile setting device, comprising: a pile setting machine for rotating and sinking a concrete pile; and an auger driving unit for applying a rotating force and a thrust to an auger drill in the pile separately from the pile setting machine.

A disk cutter sized to close the lower end of the pile is provided, and an engaging portion for engaging with the disk cutter is provided near the tip of the auger drill, and the engaging portion is released when the auger drill is rotated reversely. The pile setting device according to claim 4, wherein the pile setting device has a connection structure.

The pile setting device according to claim 4 or 5, wherein the auger drill shaft has a built-in fluid passage communicating with the injection nozzle provided at the tip of the auger drill.