JP3610486B2

JP3610486B2 - Ground improvement device

Info

Publication number: JP3610486B2
Application number: JP2000046575A
Authority: JP
Inventors: 惠智太田; 弘中柴
Original assignee: Takenaka Corp; Takenaka Civil Engineering and Construction Co Ltd
Current assignee: Takenaka Corp; Takenaka Civil Engineering and Construction Co Ltd
Priority date: 2000-02-23
Filing date: 2000-02-23
Publication date: 2005-01-12
Anticipated expiration: 2020-02-23
Also published as: JP2001234527A

Description

【０００１】
【発明の属する技術分野】
この発明は、地盤を鉛直方向下向きに掘削し、原位置の掘削土壌中に安定材を注入し攪拌混合して改良処理する地盤改良装置の技術分野に属する。
【０００２】
【従来の技術】
従来の技術を、図１に例示した形式の地盤改良装置に基いて概説する。
ベースマシン２５の垂直なリーダー２０へ取付け固定したガイドパイプ２１に沿って昇降する中間部振れ止め２２及び下部振れ止め２３により複数本のロッド１１（駆動軸）の地上部分が支持されている。ロッド１１には、地盤改良処理機２４によって回転と押し込み力が与えられる。前記ロッド１１の先端部に、複数のロッド相互間の間隔を保持する連結軸受２６を介して撹拌掘削軸１が一連に接続されている。前記撹拌掘削軸１により地盤Ｅを鉛直方向下向きに掘削し、原位置の掘削土壌中に安定材を注入し掘削土壌と攪拌混合して地盤を改良処理することは公知に属する。
【０００３】
図１２には、従来一般の撹拌掘削軸ａを例示している。これは鉛直方向下向きに配置する２本の攪拌掘削軸ａ、ａが、各々の上下２個所を連結軸受ｋ、ｋで支持された２軸のラップ型である。２軸の攪拌掘削軸ａ、ａには、平面的に見ると回転域がラップする複数の攪拌翼ｍ…が、相互に干渉を起さないように上下方向に段差をあけて多段に取り付けられている。攪拌掘削軸ａの下端部ｂには、鉛直方向下向きに掘削機能を発揮する下向きの先端掘削カッターｃ、及び下向きの掘削刃ｆを有する半径方向にほぼ水平な掘削翼ｅが取り付けられている。符号ｎは安定材の注出口を指す。安定材の注出口は、必要に応じて撹拌掘削軸の上部にも設け、上下の注出を切り替えて地盤改良を行うことも公知である。
【０００４】
【本発明が解決しようとする課題】
従来の地盤改良装置は、中間部振れ止め２２及び下部振れ止め２３並びに連結軸受ｋにいずれもメタル式軸受を採用している。そのためロッド１１（駆動軸）および撹拌掘削軸ａの拘束度が緩く、施工杭の芯の位置ずれや鉛直精度が低下する原因になっている。また、軸受の消耗が速く、交換頻度が高い欠点がある。
【０００５】
即ち、従来の振れ止め２２、２３は、ロッド１１の支持にメタル式軸受を採用しているため、どうしても軸受面のクリアランスが大きく必要である。一例として、ロッド外径が２６７．４ｍｍに対してメタル式軸受の内径は２８３ｍｍで、実に１５．６ｍｍのクリアランスが確保されている。したがって、前記のクリアランスが施工杭の芯の位置ずれや鉛直精度を低下させる重大原因になっている。また、メタル式軸受の場合は、金属同士の回転接触であるため、金属粉（切り粉）が飛散する程の摩耗を生じ、耐久性が低い。更に振れ止め自体の自重量がモーメント作用によって前傾現象（前垂れ）を生じ、ロッドの鉛直精度を低下させることも重大な問題点とされている。
【０００６】
次に、従来の連結軸受ｋは、撹拌掘削軸の外周に内メタルカラーを抱き合わせ、外側軸受を金属製の眼鏡型バンドで支持させた構成であり、２軸を一体に支持することにより剛性を高め、鉛直精度を高めている。しかし、やはり軸受面のクリアランスが大きく必要で、鉛直精度を低下させる原因になっているし、金属同士の回転接触であるために摩耗が早く、耐久性が低い。特に、この連結軸受ｋは地中に進入するため、前記のようにクリアランスが大きいと、砂地盤での消耗は粘性土及びシルト質地盤に比べると、約半分の寿命である。その上、摩耗が進行すると、当然のことながら前記クリアランスが一層大きくなり、掘削撹拌軸のガタツキが増幅し、鉛直精度の低下、方向性の不安定が増し、一般的な改良杭は偏心した繭形（長円形）の改良体となってしまうことが知られている。
【０００７】
そこで従来、新品の時には組立精度を上げるためにメタルカラーと外側軸受のクリアランスを１５ｍｍ程度にきつく設定している。しかし、無給油式のドライ構造であるために焼き付く原因にもなっている。かくして連結軸受ｋの交換頻度は砂地盤の場合は施工実績３０００ｍ^２を目安とし、シルト、粘土質地盤では５０００ｍ^２を目安としている。
【０００８】
以上のような理由で、従来の連結軸受は決して経済的なものとは云えず、一層のコストダウンを研究しているのが実情である。
【０００９】
次に、図１２に例示した従来の攪拌掘削軸ａは、その先端掘削カッターｃの掘削レベルが掘削翼ｅの掘削レベルと常に同じレベルであって所謂先導効果に欠ける。そのため攪拌掘削軸ａの鉛直掘削の中心を正確に保ち難く、施工杭の芯の位置ずれや鉛直精度が低下する原因になっている。
【００１０】
そこで従来、掘削対象地盤Ｅの土質に合った先端掘削カッターに交換することも検討されているが、上下を支持金具ｋ、ｋで拘束された２本の攪拌掘削軸ａ、ａの全体を、上部の軸継手ｄ、ｄの位置で切り離して交換する構造であるから、交換作業が大変面倒で時間がかかり煩わしい、という問題が生じている。
【００１１】
したがって、本発明の目的は、地盤改良装置による施工杭の芯の位置ずれや鉛直精度が低下する原因を根本的に解決すると同時に、消耗部品の耐久性の向上と交換頻度の延命化による経済性の向上を図ることであり、具体的には上述した下部振れ止め（及び場合によっては中間部振れ止めも）及び連結軸受並びに撹拌掘削軸の構造をそれぞれ改良した地盤改良装置を提供することである。
【００１２】
本発明の次の目的は、撹拌掘削軸を構成する先導掘削カッターを攪拌掘削軸とは別個独立に構成し、前記掘削の鉛直精度の確保、或いは施工杭の芯の位置ずれの防止に効果的な先導掘削カッターの選択的使用乃至交換に至便な構成に改良した撹拌掘削軸を提供することである。
【００１３】
本発明の更なる目的は、撹拌掘削軸を構成する先端掘削カッターを攪拌掘削軸とは別個独立に構成し、前記掘削対象地盤の土質に応じて最適な形式の先端掘削カッターを適宜選択して使用できる掘削対象地盤の土質に応じて最適なものを選択的に使用でき、或いはその交換に至便な構成に改良した撹拌掘削軸を提供することである。
【００１４】
【課題を解決するための手段】
上述の課題を解決するための手段として、請求項１に記載した発明に係る地盤改良装置は、
リーダー２０のガイドパイプ２１に沿って昇降する振れ止め２２、２３で複数のロッド１１が支持され、前記ロッド１１の先端部に、複数のロッド相互間の間隔を保持する連結軸受２６を介して撹拌掘削軸１が接続されており、地盤Ｅを鉛直方向下向きに掘削し、原位置の掘削土壌中に安定材を注入し掘削土壌と攪拌混合して地盤を改良処理する地盤改良装置において、
前記撹拌掘削軸１には、地盤Ｅを鉛直方向下向きに掘削する掘削刃９を有する掘削翼８が下端部に取り付けられ、同じく地盤を鉛直方向下向きに掘削する先端掘削カッターが攪拌掘削軸１とは別個独立に構成して攪拌掘削軸１の下端位置へ取り付けられていること、
前記先端掘削カッターは、掘削刃６の上部に角軸形状の軸継手３が一体的に設けられた構成であり、撹拌掘削軸１の前記下端位置に形成された角孔部５０に前記角軸部３を嵌めて着脱自在に取り付けられていることを特徴とする。
【００１５】
請求項２に記載した発明は、請求項１に記載した地盤改良装置において、
先端掘削カッターは、軸部１’の下端に先端掘削刃６が設けられ、上端に角軸形状の軸継手３が設けられ、軸部１’を中心としてスパイラル形状又はくさび形状の先端掘削翼が設けられた構成であることを特徴とする。
【００１６】
請求項３に記載した発明は、請求項１に記載した地盤改良装置において、
先端掘削カッターは、軸部１’の下端に先端掘削刃を有さないが、上端に角軸形状の軸継手３が設けられ、軸部１’を中心としてスパイラル形状又はくさび形状の先端掘削翼が設けられ、前記スパイラル形状又はくさび形状の先端掘削翼５の外縁部に掘削刃６’が取り付けられた構成であることを特徴とする。
【００１７】
請求項４に記載した発明に係る地盤改良装置は、
リーダー２０のガイドパイプ２１に沿って昇降する振れ止め２２、２３で複数のロッド１１が支持され、前記ロッド１１の先端部に、複数のロッド相互間の間隔を保持する連結軸受２６を介して撹拌掘削軸１が接続されており、地盤Ｅを鉛直方向下向きに掘削し、原位置の掘削土壌中に安定材を注入し掘削土壌と攪拌混合して地盤を改良処理する地盤改良装置において、
前記の下部振れ止め２３は、リーダー２０のガイドパイプ２１に沿って滑動するスライド金物２３ａの上下の位置に同じガイドパイプ２１を伝い転がるローラ式ガイド機構が設置され、ロッド支持部２３ｂには各ロッドの周囲を回転自在に支持する複数の受けローラ３１が設置された構成であること、
前記連結軸受２６は、ロッド１１と撹拌掘削軸１を上下一連に接続する継手軸４０が複数のローラーベアリング４１で回転自在に支持され、前記のローラーベアリング４１は水密構造に密封された構成であること、
前記撹拌掘削軸１は、下向きの掘削刃９を有する掘削翼８の位置を下端部とし、この下端部の位置から地盤を鉛直方向下向きに先導掘削するように下向きに長く突き出た先導掘削カッター２を備えており、前記先導掘削カッター２は地盤を先導掘削するに足る長さのロッド部分４を有し、その上端に角軸形態の軸継手３を有して攪拌掘削軸１とは別個独立に構成され、攪拌掘削軸１の前記下端位置に形成さた角孔部５０に前記軸継手３を嵌めて着脱自在に取り付けた構成であることをそれぞれ特徴とする。
【００２０】
【発明の実施の形態及び実施例】
請求項１及び４に記載した発明に係る地盤改良装置は、図１に実施形態を示したように、ベースマシン２５の垂直なリーダー２０のガイドパイプ２１に沿って昇降する中間部振れ止め２２及び下部振れ止め２３によって複数本のロッド１１（駆動軸）の地上部分が支持されている。前記ロッド１１の先端部に、複数本のロッド相互間の間隔を保持する連結軸受２６を介して撹拌掘削軸１が一連に接続されている。ロッド上端の地盤改良処理機２４によって与えられるロッド１１の回転及び押し込み力により撹拌掘削軸１が地盤Ｅを鉛直方向下向きに掘削し、原位置の掘削土壌中に安定材を注入し掘削土壌と攪拌混合して地盤を改良処理するものである。
【００２１】
本発明の特長として、前記の下部振れ止め２３は、図１Ａ及び図２Ａ、図３に構造詳細を示したように、前記リーダー２０のガイドパイプ２１に沿って滑動するスライド金物２３ａの上下の位置に、ローラ式ガイド機構として左右２本の前記ガイドパイプ２１、２１をそれぞれ伝い転がる受けガイドローラ３０が、図２Ａで明らかなように平面的に見て直角２方向を一組として設置され、もってスライド金物２３ａの昇降時のブレを防ぎ、且つ前傾現象（前垂れ）を防止するローラ式ガイド機構が構成されている。もっとも、ローラ式ガイド機構は、図２Ｂに示したように、左右２本のガイドパイプ２１、２１の間にまたがる長さで両端にフランジ３３を有する１本の共通な長ローラ３２で兼用するものとし、更に各ガイドパイプ２１を抱えるほぼ１／４円弧状のホルダ金物３４を付設した構成などで実施することができる。
【００２２】
一方、ロッド支持部２３ｂには、図２Ａと図３に詳示したように、各ロッド１１の周囲を直角４方向に回転自在に支持する４個ずつの受けローラ３１が設置された構成のローラ式ガイド機構が設けられている。各受けローラ３１は、それを支持する軸受板のボルトを操作して着脱しメンテナンス等が行われる。
【００２３】
つまり、従来のメタル軸受方式から受けローラ３１によるローラ式ガイド機構で支持する構造に改良し、且つ支持部のクリアランス許容値も２〜３ｍｍと極めてタイトにして高い拘束力を確保できる構成としている。また、ローラ軸受方式であるため、金属同士の滑り接触のように金属粉が飛散するほどの激しい摩耗は発生せず、環境保全に良好であるほか、耐摩耗性、耐久性は３〜４倍ほども向上する。従って、前記上下の受けローラ３０による昇降時のブレ防止、前傾現象（前垂れ）の防止効果との相乗により、前記ロッド１１を常にリーダー２０のガイドパイプ２１と平行に案内して、鉛直精度の高い掘削を可能ならしめる。
【００２４】
次に、撹拌掘削軸１と共に地中に貫入される前記連結軸受２６は、図１Ｂと図４及び図５に詳示したとおり、前記ロッド１１と撹拌掘削軸１とを上下一連に接続する継手軸４０が、ラジアル、スラスト兼用型（アンギュラー型式）である上下２個のローラベアリング４１、４１で回転自在に支持するローラ式ガイド機構が実施されている。したがって、ローラ支持部のクリアランス許容値を限りなく微小にして高い拘束力を確保し、掘削の鉛直精度向上が図れる。そして、ベアリング外ケース４２の上下はＯリングを多用したシール蓋ケース４３、４３により塞がれ、前記ローラベアリング４１は水密構造に密封されている。しかもグリース給油方式として耐久性、耐摩耗性の向上をはかり、ひいてはローラベアリング４１等の消耗部品の交換頻度を延命化して経済性の向上も図っている。
【００２５】
前記継手軸４０の上端の角軸部４０ａへ、管状をなすロッド１１の下端部を嵌めて接続する。また、下端の角孔部４０ｂへ、撹拌掘削軸１の上端の後述する角軸部が嵌め込まれ接続される。前記ベアリング外ケース４２に取り付けた継手板４４が、例えば図１Ｂのようにセンサー（又は計測）ボックス４６を介して、又は図４のように繋ぎ材４５により直接左右２個のベアリング外ケース４２同士を一定の間隔で接合されている。
【００２６】
ちなみに、上記連結軸受２６の交換頻度は、５０００ｍ^２毎の定期点検と消耗品の交換を目安とする。耐久性は、従来の約１０倍の３００００ｍ^２毎のオーバーホールを目安とする。グリース給油に関しては、内部よりの連続送り出し方式を採用して、地中貫入時でも給油を可能にし、もって軸受内部に外部からの異物が進入することを防ぐ構成とされている。
【００２７】
次に、前記撹拌掘削軸１は、図１に示したとおり、その先端部に、地盤を鉛直方向下向きに先導掘削する、下向きに長く突き出た先導掘削カッター２を備えた構成とされている（以上、請求項４に記載の発明）。
【００２８】
したがって、上記構成の地盤改良装置によれば、地盤を鉛直方向下向きに先導掘削する先導掘削カッター２による先導効果（芯出し効果）と、その撹拌掘削軸１を支持する連結軸受２６、及びロッド１１を支持する下部振れ止め２３それぞれのクリアランス許容値が限りなく微小で高い拘束力を保持し、掘削の鉛直精度を高める作用との相乗効果で、施工杭の芯の位置ずれがなく、鉛直精度の高い地盤改良工事を可能にする。
【００２９】
次に、撹拌掘削軸１の実施形態を図６に示している。
【００３０】
この撹拌掘削軸１は、図１に基いて既に説明したように、地盤を鉛直方向下向きに掘削し、原位置の掘削土壌中に安定材を注入し掘削土壌と攪拌混合し、軟弱地盤を改良処理する場合に好適な構造であり、地盤を鉛直方向下向きに先導掘削するように下向きに長く突き出た先導掘削カッター２を備えている。
【００３１】
この撹拌掘削軸１は、上端部の角軸構造をなす軸継手７、７を、上述した連結軸受２６（例えば図４参照）の角孔部４０ｂへ接続してロッド１１と一連に接続される。また、並列する２本（但し、本数は２本の限りではない）の攪拌掘削軸１、１は、第２連結軸受１２で下部をも支持され、その位置より上方部分に、多段の撹拌翼１０が平面的に見て相互にラップする大きさで設けられていることは従来公知のものと変わらない。第２連結軸受１２もまた、図５に示したと同様なローラベアリング構造とされている。
【００３２】
この撹拌掘削軸１の特長は、上記した先導掘削カッター２が、攪拌掘削軸１とは別個独立に構成され、攪拌掘削軸１の下端位置へ着脱自在に取り付けられていることである。その前提として、当該攪拌掘削軸１は、下向きに掘削刃９を有する掘削翼８の位置までを下端部とし、その下端部が軸継手要素である角孔部５０に形成されている。
【００３３】
上記した独立構造の先導掘削カッター２は、その上端に角軸形態の軸継手３を有し、この軸継手３が上記撹拌掘削軸１の下端に設けられた角孔部５０へ嵌め込まれ一連に接続される構成である。先導掘削カッター２は、前記軸継手３の下方部分を地盤の先導掘削の作用（芯出し作用）に必要十分な長さ、一例として長さ８５０ｍｍ程度のロッド部分４に形成され、その下端部に先端掘削刃６が下向きに取り付けられている。
【００３４】
従って、上記構成の撹拌掘削軸１は、掘削対象地盤の性状、あるいは要求する鉛直掘削精度に応じてロッド部分４の長さが異なる先導掘削カッター２を選択的に使用すること、及び後述する先端掘削カッターの選択的な使用を可能にするのである。
【００３５】
次に、図７以下は、請求項１〜３に記載した発明の実施形態であって、地盤改良装置及びそのロッド先端へ接続して使用する撹拌掘削軸に関し、上記先導掘削カッター２と同様な考え方で、構成の一部分である先端掘削刃６などを撹拌掘削軸の下端部へ着脱自在に構成した実施例を示している。
【００３６】
先ず図７の実施形態は、地盤を鉛直方向下向きに掘削し、原位置の掘削土壌中へ安定材を注入し掘削土壌と攪拌混合して地盤を改良処理する地盤改良装置に使用する攪拌掘削軸１の構成として、地盤を鉛直方向下向きに掘削する掘削刃９を有する掘削翼８が、一例として回転半径５００ｍｍの大きさで攪拌掘削軸１の下端部に取り付けられている。そして、前記掘削翼８の中心に位置する下向きの先端掘削刃６が、一種の先端掘削カッターとして攪拌掘削軸１とは別個独立に構成され、導攪拌掘削軸１の最下端位置に形成した角孔部５０へ着脱自在に取り付ける構成である（請求項１に記載の発明）。
【００３７】
独立構造の先端掘削刃６は、その上部に角軸形状の軸継手３が一体的に設けられた構成である。この先端掘削刃６は、前記掘削翼８の中心位置であって攪拌掘削軸１の最下端位置に軸継手要素として設けられた角孔部５０へ前記軸継手３を嵌め込んで取付け固定されるのである。
【００３８】
なお、図７の撹拌掘削軸１は、軟弱土質に対して攪拌効果を高めるため、多段の撹拌翼１０の一部を、下向きの掘削刃９を有する掘削翼８、及び上向きの掘削刃９’を有する掘削翼８’にそれぞれ置換して、１軸あたり上下に合計３箇所取り付けられている。
【００３９】
上記構成の撹拌掘削軸１は、例えば先端掘削刃６が摩耗したり損傷して新しいものに交換する必要が生じた場合、又は後述するように地盤の掘削当初や途中段階で地盤の土質が変化し、適正タイプの先端掘削刃６へ交換する必要の都度、当該先端掘削刃６だけを部品の如くに交換して攪拌掘削軸１へ脱着すればよいので、その交換作業（脱着作業）を至極簡便に行える。
【００４０】
次に、図８は、請求項２に記載の発明に係る、特に粘性土の地盤改良に好適な撹拌掘削軸１の実施形態を示している。
【００４１】
この攪拌掘削軸１の場合は、先端掘削カッター６０が別個独立の構成とされている。先端掘削カッター６０は、軸部１’の下端に先端掘削刃６が取り付けられているほか、軸部１’の約下半分の外周に、粘性土に好適なスパイラル形状の先端掘削翼５が取り付けられ、この先端掘削翼５の下端縁にも掘削刃６’が下向きに取り付けられた構成である。軸部１’の上端に角軸形状の軸継手３が設けられ、前記撹拌掘削軸１の下端部に形成した軸継手要素としての角孔部５０へ嵌め込まれ着脱自在に取り付けられる。
【００４２】
図９は、同じく請求項２（及び請求項３）に記載の発明に係るもので、特に礫層の地盤改良に好適な撹拌掘削軸１の実施形態を示している。
【００４３】
この撹拌掘削軸１は、先端掘削カッター６１が別個独立の構成とされている。先端掘削カッター６１は、軸部１’の下端に下向きの先端掘削は６が取り付けられていると共に、同軸部１’の約下半分の外周に、硬質の礫の粉砕に適したくさび形状の先端掘削翼５が螺旋状に取り付けられており、この先端掘削翼５の外縁部に下向きの掘削刃６’が複数取り付けられた構成である。軸部１’の上端に角軸形状の軸継手３が設けられ、前記撹拌掘削軸１の下端部に形成した軸継手要素としての角孔部５０へ嵌め込まれ着脱自在に取り付けられることは、上記の実施例と同じである。
【００４４】
更に、図１０及び図１１は、請求項２又は３に記載の発明に係るもので、あらゆる掘削対象地盤の土質に対応できるように形状、大きさを異にする先端掘削カッターの実施形態（バリエーション）を示している。
【００４５】
先ず図１０Ａは一般土質用の先端掘削用カッター６２の実施形態を示しており、図１０Ｂは砂礫、玉石層に適する先端掘削カッター６３を示している。図１０Ｃは砂礫、玉石、転石層や岩盤層の掘削に適する先端掘削カッター６４、図１０Ｄは砂礫、玉石層に好適な先端掘削カッター６５の実施形態を示している。
【００４６】
各先端掘削カッター６２〜６５は、適用する土質に対応する形状、大きさの先端攪拌翼５を軸部１’を中心として有し、下向きの掘削刃６、６’を有するか、又は有しない構成とされている。更に、軸部１’の上端に角軸形状の軸継手３が設けられ、上述した撹拌掘削軸１の下端部に形成した軸継手要素としての角孔部５０へ嵌め込まれ着脱自在に取り付けられることは、上記の各実施例と同じである。
【００４７】
また、図１１Ａは砂礫、玉石、転石層の掘削に適する先端掘削カッター６６の実施形態を示し、図１１Ｂは一般土質、砂礫層に適する先端掘削カッター６７を示し、図１１Ｃは玉石、転石層に適する先端掘削カッター６８、図１１Ｄは転石、岩盤層の掘削に好適な先端掘削カッター６９の実施形態を示している。
【００４８】
各先端掘削カッター６６〜６９は、やはり適用する土質に対応する形状、大きさの先端攪拌翼５を軸部１’を中心として有し、下向きの掘削刃６、６’を有するか、又は有しない構成とされている。更に、軸部１’の上端に角軸形状の軸継手３が設けられ、上述した撹拌掘削軸１の下端部に形成した軸継手要素としての角孔部５０へ嵌め込まれ着脱自在に取り付けられることは、上記の各実施例と同じである。
【００４９】
したがって、上記図８〜図１１に示したような先端掘削カッター６０〜６９によれば、地盤の掘削当初ないし掘削途中の地盤の土質が変化した段階で、掘削対象地盤の土質に応じて最適なものを選択して簡便に交換・使用することができ、鉛直精度を保ちながら地盤改良を能率的に行うことができる。
【００５０】
なお、上述した各種の先端掘削カッター６０〜６９は、鉛直精度が求められる比較的深い地盤改良に好適な実施形態として説明したが、鉛直精度をさほど要しない浅い改良深度の地盤においても勿論好適に使用できる。
【００５１】
【発明の奏する効果】
請求項４に記載の発明によれば、先導掘削カッター２の先導効果（芯出し効果）と同時に、ロッド（駆動軸）１１を案内する少なくとも下部振れ止め２３、及びロッド１１と撹拌掘削軸１とを接続する連結軸受２６をそれぞれローラ式ガイド機構で構成したので、極めて高い鉛直精度で繭形に変形しない改良杭から成る地盤改良処理を実現することができる。のみならず、耐久性と耐摩耗性に優れるので、交換頻度が低く、経済性の高い地盤改良装置を提供できる。
【００５２】
また、請求項１乃至３に記載の発明は、先端掘削カッターを、攪拌削軸１とは別個独立に構成したので、掘削対象地盤の土質に応じて適切なものを選択して、部分的に簡便に交換して使用でき、経済的で高品質の地盤改良を経済的に達成できる。
【図面の簡単な説明】
【図１】地盤改良装置の主要部を示した立面図で、Ａは下部振れ止めの拡大図、Ｂは連結軸受の拡大図である。
【図２】Ａ、Ｂは下部振れ止めの異なる実施形態を示す平面図である。
【図３】下部振れ止めの正面図である。
【図４】連結軸受の実施形態を示した正面図である。
【図５】連結軸受の内部構造の詳細な断面図である。
【図６】攪拌掘削軸の実施形態を示した正面図である。
【図７】撹拌掘削軸の実施形態を示した正面図である。
【図８】撹拌掘削軸の実施形態を示した正面図である。
【図９】撹拌掘削軸の実施形態を示した正面図である。
【図１０】Ａ〜Ｄは先端掘削カッターの異なる実施形態を示した正面図である。
【図１１】Ａ〜Ｄは先端掘削カッターの異なる実施形態を示した正面図である。
【図１２】従来の撹拌掘削軸を示した正面図である。
【符号の説明】
２０リーダー
２３下部振れ止め
１１ロッド（駆動軸）
２６連結軸受
１攪拌掘削軸
２１ガイドパイプ
２３ａスライド金物
３０受けガイドローラ
２３ｂロッド支持部
３１受けローラ
４１ローラベアリング
４３シール蓋ケース
２先導掘削カッター
３軸継手
４ロッド部分
６先端掘削刃
５掘削翼
９掘削刃[0001]
BACKGROUND OF THE INVENTION
The invention drilling ground vertically downward, belongs to the technical field of soil improvement device for improving the processing and mixing and stirring were injected stable material excavated soil in situ.
[0002]
[Prior art]
The prior art will be outlined based on a ground improvement device of the type illustrated in FIG.
The ground portion of the plurality of rods 11 (driving shafts) is supported by an intermediate steady rest 22 and a bottom steady rest 23 that move up and down along a guide pipe 21 attached and fixed to a vertical leader 20 of the base machine 25. The rod 11 is given rotation and pushing force by the ground improvement processing machine 24. The stirring excavation shaft 1 is connected in series to a tip end portion of the rod 11 via a connection bearing 26 that maintains a distance between a plurality of rods. It is well known to excavate the ground E vertically by the stirring excavation shaft 1, inject a stabilizer into the original excavated soil, and stir and mix with the excavated soil to improve the ground.
[0003]
FIG. 12 illustrates a conventional general agitation excavation shaft a. This is a two-shaft lap type in which two stirring excavation shafts a, a arranged downward in the vertical direction are supported by connecting bearings k, k at two upper and lower portions. A plurality of stirring blades m, whose rotational areas wrap in a plan view, are attached to the two stirring excavation shafts a and a in multiple stages with vertical steps so as not to interfere with each other. ing. A lower end portion b of the agitating excavation shaft a is attached with a downward tip excavation cutter c that exhibits a downward excavation function in the vertical direction and a substantially horizontal excavation blade e having a downward excavation blade f. The symbol n indicates the outlet for the stabilizer. It is also known that a stabilizer outlet is provided at the upper part of the stirring excavation shaft as necessary, and the top and bottom extraction is switched to improve the ground.
[0004]
[Problems to be solved by the present invention]
The conventional ground improvement device employs metal bearings for the intermediate steady rest 22, the bottom steady rest 23, and the connecting bearing k. For this reason, the degree of restraint of the rod 11 (drive shaft) and the agitation excavation shaft a is loose, which causes the displacement of the core of the construction pile and the vertical accuracy. In addition, there are disadvantages that the bearing is consumed quickly and the replacement frequency is high.
[0005]
That is, since the conventional steady rests 22 and 23 employ a metal bearing for supporting the rod 11, the clearance of the bearing surface is inevitably required to be large. As an example, the outer diameter of the rod is 267.4 mm, the inner diameter of the metal bearing is 283 mm, and a clearance of 15.6 mm is actually secured. Therefore, the clearance is a serious cause of the displacement of the core of the construction pile and the vertical accuracy. Moreover, in the case of a metal bearing, since it is a rotation contact between metals, it is worn out to the extent that metal powder (cutting powder) is scattered, and its durability is low. Furthermore, it is also considered a serious problem that the weight of the steady rest itself causes a forward tilting phenomenon (forward sagging) due to the moment action, and lowers the vertical accuracy of the rod.
[0006]
Next, the conventional coupling bearing k has a configuration in which an inner metal collar is laced on the outer periphery of the stirring excavation shaft, and the outer bearing is supported by a metal spectacle-shaped band, and rigidity is achieved by supporting the two shafts integrally. To improve vertical accuracy. However, the bearing surface needs to have a large clearance, which causes a decrease in vertical accuracy, and because of the rotational contact between the metals, the wear is quick and the durability is low. In particular, since the coupling bearing k enters the ground, if the clearance is large as described above, the consumption on the sand ground is about half that of the clay and silty ground. In addition, as the wear progresses, the clearance will naturally increase further, the backlash of the excavation stirring shaft will be amplified, the vertical accuracy will be lowered, the directionality will become unstable, and the general improved pile will be eccentric. It is known that it becomes an improvement of the shape (oval).
[0007]
Therefore, conventionally, the clearance between the metal collar and the outer bearing is set to be about 15 mm in order to increase the assembly accuracy when a new one is used. However, the oil-free dry structure also causes seizure. Thus, the replacement frequency of the connecting bearing k is set to 3000 m ² as a guide for sand ground and 5000 m ² for silt and clayey ground.
[0008]
For the reasons described above, the conventional coupled bearings are not economical at all, and are actually studying further cost reduction.
[0009]
Next, the conventional agitation excavation shaft a illustrated in FIG. 12 has the excavation level of the tip excavation cutter c always the same as the excavation level of the excavation blade e and lacks the so-called leading effect. For this reason, it is difficult to accurately maintain the center of vertical excavation of the agitating excavation shaft a, which causes a shift in the position of the core of the construction pile and vertical accuracy.
[0010]
Therefore, in the past, it has also been considered to replace the tip excavation cutter suitable for the soil of the ground E to be excavated, but the two stirring excavation shafts a, a constrained by the upper and lower support brackets k, k, Since the structure is such that it is separated and replaced at the position of the upper shaft couplings d and d, there is a problem that the replacement work is very troublesome, time consuming and troublesome.
[0011]
Accordingly, an object of the present invention is to fundamentally solve the cause of the positional deviation of the pile of the construction pile by the ground improvement device and the decrease in the vertical accuracy, and at the same time, improve the durability of the consumable parts and extend the life of the replacement frequency. Specifically, it is to provide a ground improvement device in which the structure of the above-described lower steady rest (and possibly the middle steady rest), the connecting bearing, and the stirring excavation shaft are improved. .
[0012]
It is another object of the present invention, the above conductive drilling cutter constituting the stirring excavating shaft configured independently and separately stirred drilling axis, ensuring the vertical accuracy of the excavation, or effective in preventing misalignment of the core construction pile It is an object of the present invention to provide an improved agitation excavation shaft having a configuration convenient for selective use or replacement of a typical leading excavation cutter.
[0013]
A further object of the present invention is to configure the tip excavation cutter constituting the agitation excavation shaft separately from the agitation excavation shaft, and appropriately select a tip excavation cutter of the optimum type according to the soil quality of the excavation target ground. It is an object of the present invention to provide an agitation excavation shaft that can be selectively used according to the soil quality of the excavation target ground that can be used, or that is improved in a configuration that is convenient for its replacement.
[0014]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the ground improvement device according to the invention described in claim 1 is:
A plurality of rods 11 are supported by steady rests 22, 23 that move up and down along the guide pipe 21 of the leader 20, and agitation is performed at the tip of the rod 11 via a connection bearing 26 that keeps a distance between the plurality of rods. In the ground improvement device to which the excavation shaft 1 is connected, the ground E is excavated vertically downward, the stabilizer is injected into the original excavated soil, and the ground is improved by stirring and mixing with the excavated soil.
The撹 The拌excavating shaft 1, the drilling blade 8 having a drilling Kezuha 9 you excavated ground E vertically downward is attached to the lower end, likewise tip drilling cutter for excavating the ground in a vertical direction downward stirred excavation It is configured separately from the shaft 1 and is attached to the lower end position of the stirring excavation shaft 1;
The tip excavating cutter has a configuration in which an angular shaft-shaped shaft coupling 3 is integrally provided on the upper portion of the excavating blade 6, and the angular shaft 50 is formed in the square hole portion 50 formed at the lower end position of the stirring excavation shaft 1. The part 3 is fitted and detachably attached.
[0015]
The invention described in claim 2 is the ground improvement device according to claim 1,
The tip excavating cutter is provided with a tip excavating blade 6 at the lower end of the shaft portion 1 ′, an angular shaft-shaped shaft joint 3 at the upper end, and a tip- shaped excavating blade having a spiral shape or a wedge shape around the shaft portion 1 ′. It is the structure provided .
[0016]
The invention described in claim 3 is the ground improvement device according to claim 1,
The tip excavating cutter does not have a tip excavating blade at the lower end of the shaft portion 1 ′, but is provided with an angular shaft-shaped shaft joint 3 at the upper end, and has a spiral or wedge-shaped tip excavating blade centering on the shaft portion 1 ′. And a drilling blade 6 ′ is attached to the outer edge of the spiral-shaped or wedge-shaped tip-excavating blade 5.
[0017]
The ground improvement device according to the invention described in claim 4 is:
A plurality of rods 11 are supported by steady rests 22, 23 that move up and down along the guide pipe 21 of the leader 20, and agitation is performed at the tip of the rod 11 via a connection bearing 26 that keeps a distance between the plurality of rods. In the ground improvement device to which the excavation shaft 1 is connected, the ground E is excavated vertically downward, the stabilizer is injected into the original excavated soil, and the ground is improved by stirring and mixing with the excavated soil.
The lower steady rest 23 is provided with a roller-type guide mechanism that rolls along the same guide pipe 21 at the upper and lower positions of a slide hardware 23 a that slides along the guide pipe 21 of the leader 20. A plurality of receiving rollers 31 that rotatably support the periphery of
The coupling bearing 26 is configured such that a joint shaft 40 that connects the rod 11 and the stirring excavation shaft 1 in series is rotatably supported by a plurality of roller bearings 41, and the roller bearing 41 is sealed in a watertight structure. about,
The agitation excavation shaft 1 has a lower end portion of the excavation blade 8 having a downward excavation blade 9, and a leading excavation cutter 2 protruding long downward from the position of the lower end portion so as to lead the ground downward in the vertical direction. The leading excavation cutter 2 has a rod portion 4 that is long enough for leading excavation of the ground, and has a shaft joint 3 in the form of a square shaft at the upper end thereof, and is independent of the stirring excavation shaft 1. The shaft coupling 3 is fitted in a square hole portion 50 formed at the lower end position of the stirring excavation shaft 1 and is detachably attached .
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
As shown in the embodiment of FIG. 1, the ground improvement device according to the first and fourth aspects of the present invention includes an intermediate steady rest 22 that moves up and down along the guide pipe 21 of the vertical leader 20 of the base machine 25, and The ground portion of the plurality of rods 11 (drive shafts) is supported by the lower steady rest 23. The stirring excavation shaft 1 is connected in series to a tip end portion of the rod 11 via a connection bearing 26 that maintains a distance between a plurality of rods. The agitation excavation shaft 1 excavates the ground E vertically downward by the rotation and pushing force of the rod 11 provided by the ground improvement processor 24 at the upper end of the rod, and a stabilizer is injected into the original excavated soil to agitate the excavated soil. The ground is improved by mixing.
[0021]
As a feature of the present invention, the lower steady rest 23 is located at the upper and lower positions of a slide hardware 23a that slides along the guide pipe 21 of the leader 20, as shown in detail in FIGS. 1A, 2A, and 3. Further, as shown in FIG. 2A, a receiving guide roller 30 that rolls along the two left and right guide pipes 21 and 21 as roller type guide mechanisms is installed as a set in two directions perpendicular to each other. A roller-type guide mechanism is configured to prevent blurring of the slide hardware 23a when moving up and down and to prevent a forward tilt phenomenon (forward drooping). However, as shown in FIG. 2B, the roller type guide mechanism is a length that spans between the two guide pipes 21 and 21 and is shared by one common long roller 32 having flanges 33 at both ends. Furthermore, it can be implemented with a configuration in which a substantially ¼ arc-shaped holder hardware 34 holding each guide pipe 21 is attached.
[0022]
On the other hand, as shown in detail in FIGS. 2A and 3, the rod support portion 23b is provided with four receiving rollers 31 that rotatably support the periphery of each rod 11 in four directions at right angles. A type guide mechanism is provided. Each receiving roller 31 is attached and detached by operating a bolt of a bearing plate that supports the receiving roller 31 to perform maintenance or the like.
[0023]
That is, the conventional metal bearing system is improved to a structure supported by a roller type guide mechanism using the receiving roller 31, and the clearance clearance of the support portion is extremely tight at 2 to 3 mm so that a high restraining force can be secured. In addition, because it is a roller bearing system, it does not generate so much wear that metal powder is scattered like sliding contact between metals, it is good for environmental conservation, and wear resistance and durability are 3 to 4 times. It improves so much. Therefore, the rod 11 is always guided in parallel with the guide pipe 21 of the leader 20 by synergy with the effect of preventing the blur at the time of ascending / descending by the upper and lower receiving rollers 30 and the effect of preventing the forward tilting phenomenon (forward drooping). Make high excavation possible.
[0024]
Next, the coupling bearing 26 penetrating into the ground together with the stirring excavation shaft 1 is a joint that connects the rod 11 and the stirring excavation shaft 1 in series up and down as detailed in FIGS. 1B, 4 and 5. There is a roller type guide mechanism in which the shaft 40 is rotatably supported by two upper and lower roller bearings 41 and 41 that are radial and thrust combined types (angular type). Therefore, the clearance tolerance of the roller support portion can be made extremely small to ensure a high restraining force, and the vertical accuracy of excavation can be improved. The upper and lower sides of the outer bearing case 42 are closed by seal lid cases 43 and 43 using a large number of O-rings, and the roller bearing 41 is sealed in a watertight structure. Moreover, as a grease supply system, durability and wear resistance are improved, and as a result, the replacement frequency of consumable parts such as the roller bearing 41 is extended to improve economy.
[0025]
The lower end portion of the tubular rod 11 is fitted and connected to the angular shaft portion 40 a at the upper end of the joint shaft 40. Moreover, the square shaft part which the upper end of the stirring excavation shaft 1 mentions later is engage | inserted and connected to the square hole part 40b of a lower end. The joint plate 44 attached to the bearing outer case 42 is directly connected to the left and right bearing outer cases 42 via the sensor (or measurement) box 46 as shown in FIG. 1B or directly by the connecting member 45 as shown in FIG. Are joined at regular intervals.
[0026]
Incidentally, the replacement frequency of the connecting bearing 26 is based on a periodic inspection every 5000 m ² and replacement of consumables. Durability is a measure of a conventional 10 times overhaul of 30000m per ^second. With regard to grease lubrication, a continuous feed system from the inside is adopted to allow lubrication even when penetrating into the ground, thereby preventing foreign matters from entering the inside of the bearing.
[0027]
Next, as shown in FIG. 1, the stirring excavation shaft 1 is configured to include a leading excavation cutter 2 that projects the ground downward in the vertical direction and protrudes long and downward at the tip thereof ( As mentioned above, invention of Claim 4 .
[0028]
Therefore, according to the ground improvement device having the above-described configuration, the leading effect (centering effect) by the leading excavation cutter 2 for leading and excavating the ground vertically downward, the connecting bearing 26 that supports the stirring excavation shaft 1, and the rod 11. The clearance allowance of each of the lower steady rests 23 that support the shaft is extremely small and maintains a high restraining force, and the synergistic effect of increasing the vertical accuracy of excavation is free of misalignment of the core of the construction pile, and the vertical accuracy Enables high ground improvement work.
[0029]
Next , an embodiment of the stirring excavation shaft 1 is shown in FIG.
[0030]
As already explained with reference to FIG. 1, this agitation excavation shaft 1 excavates the ground vertically downward, injects a stabilizer into the excavated soil at the original position, and agitates and mixes with the excavated soil to improve the soft ground. It is a structure suitable for processing, and is provided with a leading excavation cutter 2 that protrudes long and downward so that the ground is excavated downward in the vertical direction.
[0031]
The stirring excavation shaft 1 is connected in series with the rod 11 by connecting the shaft couplings 7 and 7 having an angular shaft structure at the upper end to the square hole portion 40b of the connecting bearing 26 described above (see, for example, FIG. 4). . In addition, two agitating excavation shafts 1 and 1 that are arranged in parallel (however, the number is not limited to two) are also supported at the lower part by a second connecting bearing 12, and a multistage agitating blade is provided above the position. It is the same as a conventionally well-known thing that 10 is provided by the magnitude | size which wraps mutually seeing planarly. The second coupling bearing 12 also has a roller bearing structure similar to that shown in FIG.
[0032]
A feature of the agitation excavation shaft 1 is that the above-described leading excavation cutter 2 is configured separately from the agitation excavation shaft 1 and is detachably attached to the lower end position of the agitation excavation shaft 1. As a premise thereof, the stirring excavation shaft 1 has a lower end portion up to the position of the excavation blade 8 having the excavation blade 9 downward, and the lower end portion is formed in a square hole portion 50 which is a shaft coupling element.
[0033]
The above-described leading excavation cutter 2 has a shaft joint 3 in the form of a square shaft at its upper end, and this shaft joint 3 is fitted into a square hole portion 50 provided at the lower end of the stirring excavation shaft 1 in series. It is a configuration to be connected. The leading excavation cutter 2 is formed in a rod portion 4 having a length lower than the shaft coupling 3 necessary and sufficient for the ground excavation action (centering action), for example, a length of about 850 mm. The tip excavation blade 6 is attached downward.
[0034]
Therefore, the agitation excavation shaft 1 having the above-described configuration selectively uses the leading excavation cutter 2 with the rod portion 4 having a different length depending on the properties of the ground to be excavated or the required vertical excavation accuracy, and the tip described later. It enables the selective use of excavation cutters.
[0035]
Next, FIG. 7 and subsequent figures are embodiments of the invention described in claims 1 to 3 , and relate to the ground excavation device and the agitation excavation shaft used by connecting to the tip of the rod. In the concept, an embodiment in which the tip excavation blade 6 which is a part of the configuration is detachably attached to the lower end portion of the stirring excavation shaft is shown.
[0036]
First, the embodiment of FIG. 7 is a stirring excavation shaft used in a ground improvement device for excavating the ground vertically downward, injecting a stabilizer into the original excavated soil, and stirring and mixing with the excavated soil to improve the ground. As one configuration, a drilling blade 8 having a drilling blade 9 for drilling the ground vertically downward is attached to the lower end of the stirring drilling shaft 1 with a rotation radius of 500 mm as an example. A downward tip excavation blade 6 located at the center of the excavation blade 8 is configured as a kind of tip excavation cutter independently of the agitation excavation shaft 1, and is formed at the lowest end position of the guided agitation excavation shaft 1. It is the structure attached to the hole 50 so that attachment or detachment is possible (invention of Claim 1 ).
[0037]
The independent excavation tip 6 has a configuration in which a rectangular shaft-shaped shaft coupling 3 is integrally provided on the upper portion thereof. The tip excavating blade 6 is fitted and fixed by fitting the shaft coupling 3 into a square hole 50 provided as a shaft coupling element at the lowermost position of the stirring excavation shaft 1 at the center position of the excavating blade 8. It is.
[0038]
In order to enhance the agitation effect on soft soil, the agitation excavation shaft 1 in FIG. 7 includes a part of the multistage agitation blade 10 as an excavation blade 8 having a downward excavation blade 9 and an upward excavation blade 9 ′. A total of three places are attached in the vertical direction per axis.
[0039]
The agitation excavation shaft 1 having the above-described configuration changes, for example, when the tip excavation blade 6 is worn or damaged and needs to be replaced with a new one, or at the beginning or midway of excavation of the ground as described later. Whenever it is necessary to replace the tip excavating blade 6 with an appropriate type, only the tip excavating blade 6 is exchanged as a part and detached from the agitating excavation shaft 1, so that the exchanging operation (demounting operation) is extremely possible. It can be done easily.
[0040]
Next, FIG. 8 shows an embodiment of the agitation excavation shaft 1 according to the invention of claim 2 , particularly suitable for ground improvement of cohesive soil.
[0041]
In the case of this agitation excavation shaft 1, the tip excavation cutter 60 has a separate and independent configuration. The tip excavating cutter 60 has a tip excavating blade 6 attached to the lower end of the shaft portion 1 ′, and a spiral tip excavating blade 5 suitable for viscous soil attached to the outer periphery of the lower half of the shaft portion 1 ′. The excavation blade 6 ′ is also attached downward to the lower edge of the tip excavation blade 5. A square shaft-shaped shaft coupling 3 is provided at the upper end of the shaft portion 1 ′, and is fitted into a square hole portion 50 as a shaft coupling element formed at the lower end portion of the stirring excavation shaft 1 so as to be detachable.
[0042]
FIG. 9 also relates to the invention described in claim 2 (and claim 3) , and shows an embodiment of the agitation excavation shaft 1 particularly suitable for ground improvement of a gravel layer.
[0043]
The stirring excavation shaft 1 is configured such that the tip excavation cutter 61 is separate and independent. The tip excavating cutter 61 is provided with a tip 6 for downward tip excavation at the lower end of the shaft portion 1 ′, and a wedge-shaped tip suitable for crushing hard gravel on the outer periphery of the lower half of the coaxial portion 1 ′. The excavation blade 5 is attached in a spiral shape, and a plurality of downward excavation blades 6 ′ are attached to the outer edge portion of the tip excavation blade 5. The shaft-shaped shaft coupling 3 is provided at the upper end of the shaft portion 1 ′, and is fitted into the square hole portion 50 as a shaft coupling element formed at the lower end portion of the stirring excavation shaft 1 so as to be detachably attached. This is the same as the embodiment.
[0044]
Furthermore, FIG.10 and FIG.11 concerns on invention of Claim 2 or 3, and is embodiment (variation of a tip excavation cutter from which a shape and a magnitude | size differ so that it can respond to the soil quality of all excavation object grounds. ).
[0045]
First, FIG. 10A shows an embodiment of the tip excavation cutter 62 for general soil, and FIG. 10B shows a tip excavation cutter 63 suitable for gravel and cobblestone layers. FIG. 10C shows an embodiment of a tip excavation cutter 64 suitable for excavation of gravel, cobblestone, boulder layer and bedrock layer, and FIG. 10D shows an embodiment of a tip excavation cutter 65 suitable for gravel and cobblestone layer.
[0046]
Each of the tip excavation cutters 62 to 65 has the tip agitating blade 5 having a shape and size corresponding to the soil to be applied with the shaft portion 1 ′ as the center, and has or does not have the downward excavation blades 6 and 6 ′. It is configured. Furthermore, a shaft-shaped shaft coupling 3 is provided at the upper end of the shaft portion 1 ′, and is fitted into the square hole portion 50 as a shaft coupling element formed at the lower end portion of the above-described stirring excavation shaft 1 so as to be detachable. Is the same as in the above embodiments.
[0047]
11A shows an embodiment of a tip excavation cutter 66 suitable for excavation of a gravel, cobblestone, and boulder layer, FIG. 11B shows a tip excavation cutter 67 suitable for general soil and a gravel layer, and FIG. 11C shows a cobblestone and a cobblestone layer. A suitable tip excavation cutter 68, FIG. 11D shows an embodiment of a tip excavation cutter 69 suitable for excavation of boulders and rock formations.
[0048]
Each of the tip excavation cutters 66 to 69 has the tip agitating blade 5 having a shape and size corresponding to the soil to be applied, with the shaft portion 1 ′ as the center, and has the downward excavation blades 6 and 6 ′. It is set not to be configured. Furthermore, a shaft-shaped shaft coupling 3 is provided at the upper end of the shaft portion 1 ′, and is fitted into the square hole portion 50 as a shaft coupling element formed at the lower end portion of the above-described stirring excavation shaft 1 so as to be detachable. Is the same as in the above embodiments.
[0049]
Therefore, according to the tip excavation cutters 60 to 69 as shown in FIG. 8 to FIG. 11, the optimum excavation is performed according to the soil quality of the ground to be excavated at the stage when the ground soil is changed during the initial excavation or during the excavation. It can be easily replaced and used by selecting one, and the ground can be improved efficiently while maintaining the vertical accuracy.
[0050]
In addition, although various tip excavation cutters 60-69 mentioned above were demonstrated as a suitable embodiment for the comparatively deep ground improvement in which vertical accuracy is calculated | required, of course, also in the ground of the shallow improvement depth which does not require the vertical accuracy so much suitably. Can be used.
[0051]
[Effects of the invention]
According to the invention described in claim 4 , at the same time as the leading effect (centering effect) of the leading excavation cutter 2, at least the lower steady rest 23 that guides the rod (drive shaft) 11, the rod 11, the stirring excavation shaft 1, Since the connecting bearings 26 for connecting the two are constituted by the roller type guide mechanisms, it is possible to realize the ground improvement process composed of the improved piles that do not deform into a bowl shape with extremely high vertical accuracy. Moreover, since it is excellent in durability and wear resistance, it is possible to provide a ground improvement device with low replacement frequency and high economic efficiency.
[0052]
Further, an invention according to claims 1 to 3, the tip end drilling cutter, since it is configured independently and separately stirred Kezujiku 1, select the one that best meets the soil of excavation ground, partially It can be easily exchanged for use, and economical and high-quality ground improvement can be achieved economically.
[Brief description of the drawings]
FIG. 1 is an elevation view showing a main part of a ground improvement device, in which A is an enlarged view of a lower steady rest and B is an enlarged view of a connecting bearing.
FIGS. 2A and 2B are plan views showing different embodiments of a lower steady rest. FIGS.
FIG. 3 is a front view of a lower steady rest.
FIG. 4 is a front view showing an embodiment of a coupling bearing.
FIG. 5 is a detailed cross-sectional view of the internal structure of the coupling bearing.
FIG. 6 is a front view showing an embodiment of a stirring excavation shaft.
FIG. 7 is a front view showing an embodiment of a stirring excavation shaft.
FIG. 8 is a front view showing an embodiment of a stirring excavation shaft.
FIG. 9 is a front view showing an embodiment of a stirring excavation shaft.
10A to 10D are front views showing different embodiments of the tip excavation cutter.
11A to 11D are front views showing different embodiments of the tip excavation cutter.
FIG. 12 is a front view showing a conventional stirring excavation shaft.
[Explanation of symbols]
20 Leader 23 Lower steady rest 11 Rod (drive shaft)
26 Connecting bearing 1 Stirring excavation shaft 21 Guide pipe 23a Slide hardware 30 Receiving guide roller 23b Rod support 31 Receiving roller 41 Roller bearing 43 Seal lid case 2 Lead excavation cutter 3 Shaft coupling 4 Rod portion 6 Tip excavation blade 5 Excavation blade 9 Excavation blade

Claims

Plurality of rods leader (20) of the guide pipe stop shake up and down along the (21) (22, 23) (11) is supported, the a tip portion of the rod (11), the spacing between the plurality of rods mutually The agitation excavation shaft ( 1 ) is connected via a coupling bearing ( 26 ) that holds the
In the ground improvement device which excavates ( E ) vertically downward, injects a stabilizer into the original excavated soil, mixes with the excavated soil and improves the ground,
A drilling blade ( 8 ) having a drilling blade ( 9 ) that drills the ground ( E ) downward in the vertical direction is attached to the lower end of the agitated drilling shaft ( 1 ) , and a tip that also excavates the ground vertically downward the drilling cutter is mounted to constitute separately and independently to the lower end position of the stirring drilling shaft (1) and the agitating drilling axis (1),
The tip excavation cutter has a configuration in which an angular shaft-shaped shaft coupling ( 3 ) is integrally provided on the upper portion of the excavation blade ( 6 ) , and a square hole formed at the lower end position of the stirring excavation shaft ( 1 ). A ground improvement device characterized in that the angular shaft portion ( 3 ) is fitted to the portion ( 50 ) and is detachably attached.

The tip excavation cutter is provided with a tip excavation blade ( 6 ) at the lower end of the shaft portion ( 1 ′ ) , an angular shaft-shaped shaft coupling ( 3 ) is provided at the upper end, and has a spiral shape centering on the shaft portion ( 1 ′ ). The ground improvement device according to claim 1, wherein the ground improvement device is provided with a wedge-shaped tip excavation blade ( 5 ) .

Tip drilling cutter, 'but no tip digging edge at the lower end of the shaft coupling of square shaft shape (3) is provided at the upper end, the shaft portion (first shaft portion (1)' spiral shape or a) as the center A wedge-shaped tip excavating blade ( 5 ) is provided, and an excavating blade ( 6 ′ ) is attached to an outer edge portion of the spiral-shaped or wedge-shaped tip excavating blade ( 5 ). Item 1. The ground improvement device according to item 1.

Plurality of rods leader (20) of the guide pipe stop shake up and down along the (21) (22, 23) (11) is supported, the a tip portion of the rod (11), the spacing between the plurality of rods mutually The agitation excavation shaft ( 1 ) is connected via a coupling bearing ( 26 ) that holds the
In the ground improvement device which excavates ( E ) vertically downward, injects a stabilizer into the original excavated soil, mixes with the excavated soil and improves the ground,
Lower bracing (23), the leader (20) of the guide along the pipe (21) rolling down along the same guide pipe (21) to position the upper and lower sliding fittings (23a) to slide roller guide mechanism is installed, The rod support portion ( 23b ) has a configuration in which a plurality of receiving rollers ( 31 ) that rotatably support the periphery of each rod are installed.
The connecting bearing (26) is rotatably supported by a rod (11) and stirred for drilling shaft joint shaft connecting the (1) in the vertical series (40) a plurality of roller bearings (41), wherein the roller bearings ( 41 ) is a structure sealed in a watertight structure;
The stirring excavation shaft ( 1 ) has a lower end portion at the position of the excavation blade ( 8 ) having the downward excavation blade ( 9 ), and is long downward so as to lead the ground vertically downward from the position of the lower end portion. A leading excavation cutter ( 2 ) is provided, the leading excavation cutter ( 2 ) has a rod portion ( 4 ) having a length sufficient for leading excavation of the ground, and an angular shaft-shaped shaft coupling ( 3) is configured independently of the stirring drilling axis (1) a, the shaft coupling (3 square hole portion formed in said lower end position of the stirring drilling axis (1) (50)) is fitted a Ground improvement devices, each characterized by being detachably mounted.