JP3757415B2 - Ground improvement method and ground improvement equipment - Google Patents

Ground improvement method and ground improvement equipment Download PDF

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JP3757415B2
JP3757415B2 JP2001307143A JP2001307143A JP3757415B2 JP 3757415 B2 JP3757415 B2 JP 3757415B2 JP 2001307143 A JP2001307143 A JP 2001307143A JP 2001307143 A JP2001307143 A JP 2001307143A JP 3757415 B2 JP3757415 B2 JP 3757415B2
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美好 忠平
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忠平 直哉
宮越 美由紀
関口 明子
忠平 彩乃
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【０００１】
【発明が属する技術分野】
本発明は、地盤改良工法と地盤改良装置に関する。
【０００２】
【発明が解決しようとする課題】
従来、この種の地盤改良工法において充填材を使用するものとして、特開昭５６−５２２１９号公報には、全周水平噴射ヘッドを有する注入管を砂質地盤中の所定深さに挿入し、前記全周水平噴射ヘッドを通じて水又は空気を砂質地盤中に水平方向に噴射して土粒子を移動収縮させ、その移動収縮によって生じた空隙中に充填材を注入し固化させる砂質地盤の改良工法（公報特許請求の範囲）が提案され、圧力水又は圧力空気を水平に噴射し、
圧力水又は圧縮空気による衝撃で土粒子の移動収縮（公報第８欄第１〜２行）するものであるが、充填材として、セメント系，水ガラス系等の如く収縮せずあまり膨脹しない硬化材（公報第８欄第７〜９行）を用いており、このように硬化材を用いるものであるから、
材料費がかかるという問題がある。また、特開平７−２５２８２３号公報には、高圧ジェット噴流と機械攪拌との併用により地中に固結杭を造成するに際し、地中に挿入する管の長手方向に間隔を設けて取付けた攪拌翼に設けて固化材又は水の高圧噴流及び該高圧噴流の周りを覆う空気噴流を噴出する少なくとも２個のノズルを用い仕上がり杭径の制御方法（公報特許請求の範囲）が提案されているが、この方法も硬化材としてはセメントミルク，モルタル，薬剤など（工法第４欄第１〜２行）を用いるものであるから、材料費がかかるという問題がある。
【０００３】
そこで、上記のように硬化材を用いることなく地盤改良を行う工法として、特開平３−２８１８１５号公報には、振動部の振動と先端部からのジェット水の噴射によりバイブロフロットを地盤中に貫入し、さらに砕石や砂利等の中詰め材を投入しながら引き抜いて、
周囲の地盤を締固めると共に地盤中に中詰め材の柱を形成する（公報第１頁右欄第17行〜第２頁右上欄第１行）工法が記載され、また、バイブロフローテーション工法における振動部の振動と振動部先端からの第１の圧縮空気の噴射とにより前記振動締固め装置を地中に貫入して穿孔を形成すると同時に、前記振動締固め装置の外周からの第２の圧縮空気の噴射と前記ロッド部の軸方向に設けた偏平板の作用により前記外周の空隙を拡幅保持する工程と、前記穿孔を形成した後、振動締固め装置を引き抜きながら前記空隙に中詰め材を投入する工程とからなる振動締固め工法（公報特許請求の範囲）が提案されている。
【０００４】
上記特開平３−２８１８１５号公報のジェット水を噴射する工法では、ジェット水により地表に泥水が吐き出され、この泥水と共に地中の水溶性微細土粒子等が排出され、この水溶性微細土粒子は、腐食土等の含まれる成分で、加重支持土質としては不適当であって、締め固めを行っても強度が得られないものである。しかし、単にジェット水を噴射するだけでは、上記の水溶性微細土粒子等の締め固めに不向きな成分を効率良く排出することができない。また、上記振動締固め工法のように圧縮空気の噴射と振動により締め固める工法では、締め固めに限界があると共に、その中詰め材周囲の地盤を効率良く締め固めることができない。
【０００５】
そこで、同一出願人は、特開２０００−８０６３８号公報において、杭の下端に圧縮水を噴射する圧縮水用ノズルと圧縮空気を噴射する圧縮空気用ノズルとを設け、それらノズルから圧縮水と圧縮空気とを噴射して地中に所定深さまで打ち込んで掘削孔を形成し、前記圧縮水と圧縮空気との噴射により地中の微細粒子を前記杭に沿って上昇させると共に、
地表に排出し、この微細粒子を排出した後、前記圧縮空気の噴射を停止又は噴射圧を下げ、前記杭を引き抜くと共に、この引き抜き時に掘削孔内に中詰め材を投入する地盤改良工法を提案しており、この地盤改良によれば、下方に向かって噴射した圧縮空気と圧縮水とにより、鋼矢板の下方の掘削孔において、土粒子（土塊）の攪拌が行われ、圧縮空気が泡となって上昇する際に土粒子を揺動して分解が行われ、これにより分解した微細粒子たる水溶性微細粒子が上昇水流と泡の上昇に伴うリフトアップ効果によりに地表に効率よく排土される。そして、掘削孔内に投入した中詰め材を圧縮水により圧密して圧密柱を形成することができる。
【０００６】
上記特開２０００−８０６３８号公報の地盤改良工法では、圧縮水と圧縮空気とを用いることにより、硬化材等が不要で、加重支持土質に不向きな水溶性微細土粒子等を良好に排出することができる。しかし、この地盤改良工法でも、単に圧縮水の圧力を上げただけでは、それ以上の効果が得られず、逆に圧縮水の使用量を削減できれば、工費の削減が可能となる。
【０００７】
そこで、本発明は、硬化材が不要で、加重支持土質に不向きな水溶性微細土粒子等を良好に排出することができ、充填した中詰め材により良好な支持力を得ることができる地盤改良工法と地盤改良装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
請求項１の地盤改良方法は、ロッドの下端に設けられ圧縮水を下方に噴射する圧縮水用ノズルと、前記ロッドの下端に設けられ圧縮空気を下方に噴射する圧縮空気用ノズルと、
前記ロッドの下端に設けられたスクリューと、前記ロッドに設けられ圧密用の圧縮空気を外周方向に噴射する圧密用圧縮空気噴射口と、前記ロッドを正逆回転駆動する回転駆動手段とを備えた地盤改良装置を用い、前記ロッドの下端から圧縮水と圧縮空気とを噴射して該ロッドを地中に所定深さまで押し込んで掘削孔を形成すると共に、前記噴射した圧縮水と圧縮空気とにより、前記掘削孔の水溶性微細粒子を地表面に排出し、前記ロッドを引き抜くと共に、この引き抜き時に前記掘削孔に中詰め材を充填する地盤改良工法であって、
前記スクリューの掘削方向回転と前記圧縮水の噴射と前記圧縮空気の下方及び外周方向への噴射を継続して前記ロッドを押し込み、水が浸透した透水層において前記ロッドの下端 から高圧な前記圧密用の圧縮空気を噴射して該圧密用の圧縮空気を掘削孔周面の土粒子間に押し込み、該掘削孔周囲の土粒子間の間隙水を外側に押し退けて圧密し、前記ロッドの下端が計画深さに達する前に、加重支持土質に不向きな前記水溶性微細土粒子の排出が少なくなったら、前記圧縮水の噴射量を削減し、この後、前記スクリューを反掘削方向に回転しながら掘削孔の計画深さまで前記ロッドを押し込み、前記掘削孔の下方に圧密された部分を形成し、この掘削孔の圧密された部分の上に前記中詰め材を充填する方法である。
【０００９】
この請求項１の構成によれば、噴射した圧縮水と圧縮空気とにより、ロッドの下方の掘削孔において、土粒子（土塊）の攪拌が行われ、土粒子を揺動して分解が行われ、これにより分解した微細粒子たる水溶性微細粒子が上昇水流に伴うリフトアップ効果によりに地表に効率よく排土される。そして、スクリューを反掘削方向に回転しながらロッドを押し込むことにより、ロッドの下方が圧密され、所定深さまで形成された掘削孔の下方は圧密された部分となり、この掘削孔内に中詰め材を充填し、この中詰め材による柱部分とその下方の圧密された部分とにより、高い支持圧が得られる。このようにスクリューの反掘削方向の回転による圧密を用いるため、圧密に必要な圧縮水の使用量を削減でき、或いは不要となる。
【００１０】
また、水が浸透した透水層において、高圧な圧縮空気を噴射し、その圧縮空気が掘削孔内で爆発的に膨張し、掘削孔周囲の土粒子間に間隙水（土粒子の間に含まれる水）を外側に押し退け、この後、間隙水が押し退けられた部分は、上方地盤加重により沈下圧密状態となる。
【００１１】
また、請求項２の地盤改良方法は、請求項１の発明において、前記透水層が地下水位より下方のピート層又は砂層である方法である。
【００１２】
この請求項２の構成によれば、特に、前記透水層が地下水位より下方のピート層又は砂層では、粘土層等に比べて、圧縮空気が掘削孔周囲の土粒子間に入り込み易く、掘削孔周囲における圧密効果が得られる。
【００１３】
また、請求項３の地盤改良装置は、請求項１又は２記載の地盤改良工法に用いられ、前記ロッドの下端が略角錐状をなすものである。
【００１４】
この請求項３の構成によれば、略角錐形状の下端を中詰め材に食い込ませて回転することにより、食い込んだ部分の中詰め材を外側に押す力が発生し、これにより中詰め材を効果的に締め固めることができる。
【００１５】
【発明の実施形態】
以下、本発明の実施例を添付図面を参照して説明する。図１〜図１６は本発明の第１実施例を示し、この地盤改良工法に用いる地盤改良装置は、図１〜図３に示すように、自走式車両１は、車体２の下部に走行手段たる無限軌道３を有し、この無限軌道３は車体２に搭載した原動機（図示せず）により駆動する。前記車体２の後部には、ショベルたるブレード４が設けられ、このブレード４は昇降駆動可能に設けられている。
【００１６】
また、車体２の前部にはリーダ５が起伏可能に設けられ、このリーダ５は前後方向の起伏装置６により、図１の鎖線に示す収納位置と地表に対してほぼ垂直な使用位置とに起伏可能になっている。尚、実際には、約５度程度だけリーダ５の上部が前側に倒れることが可能である。前記起伏装置６は、前記車体２に起伏ベース７の下部を枢着部８により前後方向起伏可能に設け、その枢着部８より後方で前記車体２に枢着部９により起伏シリンダ10の下部を枢着し、この起伏シリンダ10の伸縮杆10Ａを枢着部11により前記起伏ベース７の上部に枢着してなる。そして、前記起伏シリンダ10がリーダ５の前後方向角度調整手段である。前記起伏ベース７の前側には揺動ベース12が左右方向揺動可能に設けられ、前記起伏ベース７と揺動ベース12の上部を枢着部13により回動可能に設けると共に、前記起伏ベース７と揺動ベース12の下部を左右スライド駆動機構14により左右移動可能に設けている。そして、左右スライド駆動機構14がリーダ５の左右方向角度調整手段である。また、
前記揺動ベース12の前部に前記リーダ５を上下方向移動可能に設け、リーダ昇降手段たるスライドシリンダ15により、前記揺動ベース12に対して、リーダ５を昇降可能に設けている。したがって、図１の鎖線に示す収納位置にリーダ５を収納した状態で作業場所まで移動し、起伏シリンダ10を延ばしてリーダ５を地面に対し前後方向ほぼ垂直に合わせ、さらに、左右スライド駆動機構14により、枢着部13を中心としてリーダ５の下部を左右に回転して左右方向ほぼ垂直に合わせ、この後、スライドシリンダ15によりリーダ５の高さ位置を調節できる。尚、前記シリンダ10，15及び左右スライド駆動機構14は油圧などにより駆動する。
【００１７】
前記リーダ５の前部には案内レール21が設けられ、この案内レール21に沿ってロッド挟持体22が昇降可能に設けられ、このロッド挟持体22はチェーンを備えた昇降手段23によりリーダ５に沿って昇降する。前記ロッド挟持体22は内部に挿通したロッドを挟持及び挟持解除可能なものであって、挟持したロッドを回転する回転駆動手段24を内蔵する。また、
前記リーダ５の下部にはロッド固定手段25が固定して設けられ、該ロッド固定手段25は、
これに挿通したロッドを挟持及び挟持解除可能なものである。
【００１８】
前記車体２上にはホッパ状の収納部31が設けられ、この収納部31に中詰め材が収納され、前記収納部31の底部には送り装置たるベルトコンベア32が設けられ、このベルトコンベア32は中詰め材を後から前に送るものである。このベルトコンベア32の終端側で前記収納部31には投入路33が設けられ、この投入路33は先端側の投入口34が低くなる傾斜をなし、
その投入口34は、起立位置のリーダ５の下部まで延設されている。また、前記投入路33の両側には壁部33Ａが設けられている。そして、前記ベルトコンベア32と投入路33により、
中詰め材を投入すると投入装置35を構成している。
【００１９】
41は、掘削孔の上部に設けるホッパであり、筒部42の上部に拡大筒部43を設けてなる。
【００２０】
この例では、図４及び図５などに示すように、前記ロッドはパイプから構成された二重管51であって、この二重管51は外管52と内管53とからなり、この内管53内により圧縮水路54を形成し、前記外管52内面と内管53外面との間により圧縮空気路55を形成し、前記圧縮水路54の下端に圧縮水用ノズル56を設け、前記圧縮空気路55の下端に圧縮空気用ノズル57を設けている。さらに、前記二重管51の上端には、前記圧縮水路54に連通する水ホースアダプタ58と、前記圧縮空気路55に連通する空気ホースアダプター59とが設けられている。
そして、前記水ホースアダプター58に高圧ホース60を介して圧縮水供給装置たる高圧ポンプ61を接続し、この高圧ポンプ61が水槽62に接続され、この水槽62は複数の家庭用水道を接続して水を溜めておく。また、前記空気ホースアダプター59にホース63を介して圧縮空気供給装置たるエアーコンプレッサ64を接続している。尚、二重管51は、長さ方向中央部分を交換することにより長さ調節可能である。
【００２１】
図４などに示すように、前記二重管51の下端には、螺旋羽根であるスクリュー71が設けられている。また、その二重管51の下端に圧密用圧縮水噴射口72が設けられ、この圧密用圧縮水噴射口72からは、圧密用の圧縮空気Ａが外周方向に噴射される。
【００２２】
図５に示すように、前記圧縮水用ノズル56は、前記内管53に螺合されており、下端（先端）には噴射口81が形成されている。また、前記圧縮水用ノズル56には下方に向って縮小する角錐型外周面82が形成され、この例では、図６に示すように、角錐型外周面82は角部82Ａを有する略裁頭三角錐形状である。また、前記外管52の下端内面に雌螺子部52Ａを形成し、この雌螺子部52Ａに螺合する雄螺子部57Ａが、前記圧縮空気用ノズル57の上端外面に形成されている。さらに、前記圧縮空気用ノズル57の上端（基端）には、テーパ状内周面84が形成され、前記外管52に圧縮空気用ノズル57を螺合した状態で、前記角錐型外周面82とテーパ状内周面84との間に、前記圧縮空気路55と連通するテーパ状の案内空気路85が形成され、この案内空気路85により圧縮空気が圧縮空気用ノズル57の中央側に案内される。さらに、前記案内空気路85から前記圧縮空気用ノズル57の下端の噴射口86に至る通路87が、該圧縮空気用ノズル57の内部に形成されている。そして、前記案内空気路85と前記圧縮空気用ノズル57の噴射口86との間の長さは、前記噴射口86の直径Ｄより長く形成されている。また、前記圧縮水用ノズル56の噴射口81の直径ｄは、前記圧縮空気用ノズル57の噴射口56の直径Ｄより小さく形成されている。また、前記案内空気路85の断面積を、前記圧縮空気路55の断面積以上としている。
【００２３】
実験例１
この実験例１は、複数土質互層に本発明を適用した場合を検討する例であり、透明水槽91内に下層から粘土92、細砂93、中砂94、粗砂95、小砂利96を順に敷き詰めて層97を形成する。
【００２４】
図７及び図８に示すように、内管101と外管102とからなる二重管103を形成し、内管101の先端から圧縮水、内管101と外管102の間から圧縮空気を噴射可能とする。圧縮空気と圧縮水とを噴射しながら、前記二重管103の先端を前記層97内にほぼ垂直に挿入すると、二重管103の下方にフラスコ状の掘削孔が形成され、二重管103の挿入を停止し、圧縮空気と圧縮水とを噴射を継続すると、フラスコ状掘削孔98内において、土粒子の攪拌が行われ、
この攪拌により土粒子成分が分解する。すなわち砂の層であれば、砂本体とそれに含まれていた水溶性微細土粒子に分解する。比重の軽い水溶性微細土粒子は、二重管103の外周に沿う上昇水流と、圧縮空気の上昇に伴うリフトアップ効果により水と共に地上に排土される。この排土状況を地上で確認し、実際には地上に排出される水の濁り具合により確認し、水溶性微細土粒子の排土がほぼ終了したら、圧縮空気の噴射を停止し、圧縮水のみ噴射を継続する。このように圧縮空気の供給を停止すると、フラスコ状掘削孔内での攪拌力が低下し、土粒子は圧縮空気により攪拌されない比重の大きな土粒子から順次掘削孔の底部に体積し、かつ体積した土粒子は、下方に向かって噴射される圧縮水により水締めされ、隙間なく堆積し、圧縮水の噴射を続けながら徐々に二重管103を上方に引き抜くと、順次圧密された土粒子柱が形成された。
【００２５】
そして、二重管103を引く抜くと、排土された水溶性微細粒子と、土粒子が圧密された分の体積だけ、掘削孔98の上部が空洞となり、この部分に充填する中詰め材が必要となる。
【００２６】
この実験により、複数土質体積地層に高圧噴射水を噴射し、土粒子を分解でき、さらに、分解した土粒子に圧縮水と圧縮空気を供給することにより、攪拌できることが分かった。また、比重の軽い水溶性微細粒子は、空気を含む圧縮水の上昇力により良好に地表に排出される。さらに、圧縮空気の噴射を停止して圧縮水のみの噴射とすると、攪拌力が低下し、圧縮水のみの力では攪拌力の影響を受けない重たい土粒子から順次堆積していく。そして、出来上がった土粒子柱は、下から、小砂利96、粗砂95、中砂94、細砂93、粘土92となった。
【００２７】
実験例２
透明水槽91内に、粘土92、細砂93、中砂94、粗砂95、小砂利96を混合して敷き詰め、実験例１と同様に、二重管103を用いて実験を行ったところ、実験例１と同様に、出来上がった土粒子柱は、下から、小砂利96、粗砂95、中砂94、細砂93、粘土92となった。
【００２８】
このように土質、土層堆積条件を変えても、出来上がる土粒子柱は、比重の重たいものから圧密堆積することが分かった。
【００２９】
さらに、上記実験例１，２に対して圧縮水と圧縮空気の噴射圧を変えた他の実験から、
以下のことが分かった。
【００３０】
まず、土質条件の異なる実験においても、掘削孔98には下から比重の重たいものが堆積する。また、圧縮水の噴射圧を上げるように調整すれば砂類も排土できる。特に、加重支持土質として不適当な水溶性微細土粒子のみを圧縮水と圧縮空気の噴射圧の調整により任意に排土することができ、現状地盤に含まれる加重支持土質として有効な土粒子を利用し、土粒子を圧密することにより、強固な土粒子柱を作ることができる。
【００３１】
次に、施工例を図３，図９〜図１６を参照して説明する。自走式車両１により施工位置まで移動し、起伏シリンダ10を延ばしてリーダ５を前後方向ほぼ垂直に合わせ、さらに、
左右スライド駆動機構14により、枢着部13を中心としてリーダ５の下部を左右に回転して左右方向ほぼ垂直に合わせ、この後、スライドシリンダ15によりリーダ５の高さ位置を調節できる。したがって、自走式車両１位置が傾斜となっていても、リーダ５を所定の向きに調整して掘削孔151を掘削できる。また、掘削位置にはホッパ41をセットしておく。そして、まず、ホッパ41を通して、図９に示すように、二重管51の下端を地表面152に接地し、ロッド固定手段25は固定解除状態で、昇降手段23によりロッド挟持体22を降下させて二重管51を圧入すると共に、回転駆動手段24により二重管51を回転する。この場合は、スクリュー71が押し込み方向に食い込む方向である掘削方向に二重管51を回転し、同時に圧縮水Ｗを下方に噴射する。二重管51の下方の掘削孔151内においては、圧縮水Ｗと圧縮空気Ａとにより土粒子攪拌作用が発生し、その攪拌作用により既設土粒子構成（土の塊）を分解し、分解された比重の軽い水溶性微細土粒子が、二重管51の外面に沿って、上昇水流と空気のリフトアップ作用により、水と共に地表面152に排土され、さらに、スクリュー71の回転により既設土粒子構成（土の塊）の分解が良好になされる。このようにして、スクリュー71の掘削方向回転と圧縮水Ｗの噴射による掘削により二重管51を効率よく押し込むことができる。このようにして掘削で二重管51を下端側を地中に圧入したら、スクリュー71の掘削方向回転と圧縮水Ｗの噴射を継続しつつ、今度は、圧縮空気用ノズル57及び圧縮空気噴射口72から圧縮空気Ａを下方と外方に向って噴射し、図１０に示すように、これら圧縮水Ｗと圧縮空気Ａによる掘削を行う。図１１に示すように、二重管51の下端が透水層161の地下水位Ｈより下方に達すると、圧密用圧縮空気噴射口72から掘削孔151の内壁部151Ｎに向って噴射された圧縮空気Ａが掘削孔151内でー的に膨張し、内壁部151Ｎの土粒子間に入り込んで、該土粒子間の間隙水（土粒子の間に含まれる水）を押し退け、この後、図１２に示すように、間隙水が押し退けられた部分は、上方地盤加重により沈下圧密状態となり、地表面152には二重管51の周囲にすり鉢状に陥没部162が形成される。尚、透水層としては、ピート層又は砂層が挙げられる。この場合、スクリュー71の回転を止めて、
圧密用圧縮空気噴射口72からの圧縮空気Ａを内壁部151Ｎに直接的に噴射するようにしてもよい。図１２から、さらにスクリュー71の掘削方向回転と圧縮水Ｗの噴射と圧縮空気Ａの下方及び外側への噴射を継続して二重管51を押し込み、掘削を継続する。そして、加重支持土質に不向きな水溶性微細土粒子の排出が少なくなったら、圧縮水Ｗの噴射量を削減する。この後、図１３に示すように、スクリュー71を反掘削方向に回転しながら、二重管51を押し込むことにより、二重管51の下方に圧密された部分163が形成され、図１４に示すように、掘削孔151の計画深さ（最深部）まで二重管51を押込む。このように、掘削孔151の最下部に達する前に、二重管51の回転を逆方向に変えてスクリュー71を反掘削方向に回転し、圧縮水Ｗの噴射圧を下げるか、圧縮水Ｗの噴射を停止し、二重管51を下方に押し込むことにより、二重管51の下方が圧密され、所定深さまで形成された掘削孔151の下方に圧密された部分163が形成される。
【００３２】
また、掘削において、スクリュー71を用い、該スクリュー71を回転に伴う撹拌作用により、土の塊が分解される。また、スクリュー71の掘削により、均一な円筒状をなす掘削孔151を形成することができる。尚、二重管51の押込み作業において、ロッド挟持体22を最下部まで降下したら、ロッド挟持体22による挟持を解除し、ロッド固定手段25により二重管51を挟持固定し、ロッド挟持体22をリーダ５の最上部まで昇降した後、ロッド挟持体22により二重管51を挟持し、ロッド固定手段25による二重管51の挟持を解除して、再びロッド挟持手段22を降下することにより二重管51を押込むことができる。さらに、リーダ昇降手段たるスライドシリンダ15により、リーダ５を昇降して二重管51を圧入・引き抜きすることができる。
【００３３】
次に、二重管51の引き上げ時における中詰め材の投入作業について説明すると、上述したようにスクリュー71を反掘削方向に回転しながら計画深さ（最深部）まで二重管51を押込むことにより、掘削孔151の下方に圧密された部分163が形成される。その設計深さ（最深部）まで、掘削を行った後は、圧縮空気Ａの噴射を停止又は少量の噴射を継続する。そして、図３に示すように、車体２の収納部31に、中詰め材たる砕石153を収納しておき、
投入時には、ベルトコンベア32を駆動により投入口34から掘削孔151の開口部151Ａに、砕石153を該砕石153の沈下速度に合わせて供給する。この場合、ベルトコンベア32の駆動速度を調整することにより砕石153の供給量を調整できる。そして、スクリュー71の反掘削方向の回転を継続した状態で、図１４に示すように、砕石153の供給を行い、掘削孔151内に供給された砕石153は、二重管151の外周に沿って沈下し、掘削孔151の圧密された部分163上に堆積する。前記スクリュー71は反掘削方向により堆積した砕石153が圧密される。
さらに、図１５及び図１６に示すように、砕石153の投入に合わせて、すなわち掘削孔151内の砕石153の上面153Ａの高さに合わせるようにして二重管51を上下運動しながら引上げる。この場合、二重管51の上下運動により砕石上面153Ａの高さを確認し、昇降手段23を駆動して図１６に示すように二重管51の下端を砕石上面153Ａより下方に押し込み、回転する二重管51の角錐型外周面82が砕石153内に押し込み、さらに、その角錐形状の先端が回転することにより、その周囲の砕石153を外側に押す力が発生し、これにより砕石153の締め固め及び砕石周囲の掘削孔151内壁部151Ｎの締め固めが行われる。この際、二重管51の下端が砕石上面153Ａに当たれば、ロッド挟持体22の下方への加圧力が変わるから、当たった位置を自走式車両１の装置により確認できる。例えば、ロッド挟持体22を昇降する昇降手段23に二重管51から加わる反力を測定する手段を設けることができる。そして、一例として、砕石153を投入しつつ、二重管51を所定の長さだけ、例えば６０ｃｍ程度引き上げたら、この位置で下方に向かって、所定のストロークＳ、例えば１ｍのストロークＳで複数回上下動させ、回転する角錐型外周面82を砕石上面153Ａからその下方に圧入するようにして締め固めを行う。この場合、砕石153中に回転する角錐型外周面82を砕石上面153Ａからその下方に圧入することにより、この圧入力が周囲の土質の締め固め力（図１６に矢印Ｙで示す。）として働く。
【００３４】
そして、上述した工程を繰り返し、二重管51を序々に引上げ、図１７に示すように、掘削孔151のほぼ全てが供給した砕石153からなる圧密石柱154とすることができる。
【００３５】
尚、地中の固結可能な土粒子を地表面152に排土することなく圧密柱の一部に利用するようにしてもよい。
【００３６】
この工法は支持杭の深さを任意に設定でき、すなわち、支持杭の深さが支持層まで達しない深さである場合は、砕石を供給して支持杭を形成できる。また、現状地層の加重支持土質として不適当な土粒子のみを排土でき、現状地層に含まれる締め固め土質として適当な土粒子を圧密し再利用が可能であるから、供給する砕石を節約できる。さらに、中詰め材は、砕石、砂利、砂の他、コンクリートを粉砕したコンクリート砕等の固結可能な土粒子を用いることができるから、コンクリート砕等を用いれば建設廃材の再利用が可能となる。このように使用する材料が安価であり、特別な装置を用いる必要もないから、施工コストも安価となる。しかも、水と空気を用いるから薬剤等が不要である。
【００３７】 また、二重管51を引き抜く際に該二重管51を上下動し、二重管51により掘削孔151内の砕石153を叩く工法であるから、砕石153を叩くことにより、より一層砕石153が圧密されると共に、砕石153の周囲の土質を締め固めることができる。さらに、微細粒子を排出した後、圧縮水Ｗの噴射圧を下げる工法であるから、圧縮水Ｗの噴射圧を下げることにより、地中の固結可能な土粒子を地表面152に排土することがなく、その土粒子を締め固めて掘削孔151中に圧密柱を形成することができ、投入する砕石153などの材料費を削減することができる。また、このように圧縮水Ｗと圧縮空気Ａとを同時に噴射する方法において、
圧縮水用ノズル56を圧縮空気用ノズル57の上方に設けているから、圧縮水Ｗより低圧な圧縮空気Ａを良好に噴射することができる。そして、圧縮水用ノズル56から噴射された圧縮水Ｗは、その噴射口81が圧縮空気用ノズル57より細いため、圧縮空気用ノズル57内の通路87の中央側を通って外部に噴射され、同時に圧縮空気路55から案内空気路45を通って通路87内に圧縮空気Ａが流れ込み、この圧縮空気Ａはテーパ状の圧縮空気路85により通路87の中央側に案内され、この中央側を流れる圧縮水Ｗと一部が効率良く混合すると共に、前記圧縮水Ｗの流れにより周囲の圧縮空気Ａが引っ張られるようにして圧縮空気用ノズル57の噴射口86から噴射され、掘削孔151の底部まで効率良く供給される。
【００３８】
このように本実施例では、請求項１に対応して、ロッドたる二重管51の下端に設けられ圧縮水Ｗを下方に噴射する圧縮水用ノズル56と、二重管51の下端に設けられ圧縮空気Ａを下方に噴射する圧縮水用ノズル57と、二重管51の下端に設けられたスクリュー71と、二重管51に設けられ圧密用の圧縮空気Ａを噴射する圧密用圧縮空気噴射口72と、二重管51を正逆回転駆動する回転駆動手段24とを備えた地盤改良装置を用い、二重管51の下端から圧縮水Ｗと圧縮空気Ａとを噴射して地中に所定深さまで押し込んで掘削孔151を形成すると共に、噴射した圧縮水Ｗと圧縮空気Ａとにより、掘削孔 151 の水溶性微細粒子を地表面 152 に排出し、二重管 51 を引き抜くと共に、この引き抜き時に掘削孔151に中詰め材たる砕石153を充填する地盤改良工法であって、スクリュー 71 の掘削方向回転と圧縮水Ｗの噴射と圧縮空気Ａの下方及び外周方向への噴射を継続して二重管 51 を押し込み、水が浸透した透水層 161 において二重管 51 の下端から高圧な圧密用の圧縮空気Ａを噴射して該圧密用の圧縮空気Ａを掘削孔 151 周面の土粒子間に押し込み、該掘削孔 151 周囲の土粒子間の間隙水を外側に押し退けて圧密し、二重管51の下端が計画深さに達する前に、加重支持土質に不向きな水溶性微細土粒子の排出が少なくなったら、圧縮水Ｗの噴射量を削減し、この後、スクリュー71を反掘削方向に回転しながら掘削孔 151 の計画深さまで二重管51を押し込み、掘削孔 151 の下方に圧密された部分 163 を形成し、この掘削孔 151 の圧密された部分 163 の上に砕石 153 を充填するから、噴射した圧縮水Ｗと圧縮空気Ａとにより、二重管51の下方の掘削孔151において、土粒子（土塊）の攪拌が行われ、土粒子を揺動して分解が行われ、これにより分解した微細粒子たる水溶性微細粒子が上昇水流に伴うリフトアップ効果によりに地表に効率よく排土される。そして、スクリュー71を反掘削方向に回転しながら二重管51を押し込むことにより、二重管51の下方が圧密され、所定深さまで形成された掘削孔151の下方は圧密された部分163となり、この掘削孔151内に砕石153を充填し、この砕石153による柱部分とその下方の圧密された部分とにより、高い支持圧が得られる。このようにスクリュー71の反掘削方向の回転による圧密を用いるため、圧密に必要な圧縮水Ｗの使用量を削減でき、或いは不要となる。
【００３９】
また、このように本実施例では、請求項１に対応して、前記押し込み中に、水が浸透した透水層161においてロッドたる二重管51の下端から高圧な圧縮空気Ａを噴射して該圧縮空気Ａを掘削孔151周面の土粒子間に押し込み、該掘削孔151周囲の土粒子間の間隙水を外側に押し退けて圧密するから、水が浸透した透水層161において、高圧な圧縮空気Ａを噴射し、その圧縮空気Ａが掘削孔151内で爆発的に膨張し、掘削孔151周囲の土粒子間の間隙水（土粒子の間に含まれる水）を外側に押し退け、この後、間隙水が押し退けられた部分が、上方地盤加重により沈下圧密状態となり、地下水位Ｈの高い透水層161において、周囲の層を圧密した圧密石柱154を得ることができる。
【００４０】
また、このように本実施例では、請求項２に対応して、透水層161が地下水位Ｈより下方のピート層又は砂層であるから、粘土層等に比べて、圧縮空気Ａが掘削孔151周囲の土粒子間に入り込み易く、掘削孔151周囲における圧密効果が得られる。
【００４１】
また、ロッドたる二重管51の下端に設けられ圧縮水Ｗを下方に噴射する圧縮水用ノズル56と、二重管51の下端に設けられ圧縮空気Ａを下方に噴射する圧縮水用ノズル57と、二重管51の下端に設けられたスクリュー71と、二重管51に設けられ圧密用の圧縮空気Ａを噴射する圧密用圧縮空気噴射口72と、二重管51を正逆回転駆動する回転駆動手段24とを備えるから、下方に噴射した圧縮水Ｗと圧縮空気Ａとにより、二重管51の下方の掘削孔151において、土粒子（土塊）の攪拌が行われ、土粒子を揺動して分解が行われ、これにより分解した微細粒子たる水溶性微細粒子が上昇水流に伴うリフトアップ効果によりに地表に効率よく排土される。また、圧縮空気Ａの噴射とスクリュー71の回転とを併用することにより、圧縮空気Ａの泡とスクリュー71の回転とによる撹拌とによって、土粒子の分解が効果的に行われる。そして、水が浸透した透水層161において、圧密用圧縮空気噴射口72から高圧な圧縮空気Ａを噴射し、その圧縮空気Ａが掘削孔151内で爆発的に膨張し、掘削孔151周囲の土粒子間の間隙水（土粒子の間に含まれる水）を外側に押し退け、この後、間隙水が押し退けられた部分を、上方地盤加重により沈下圧密状態とすることができる。
【００４２】
また、圧密用圧縮水噴射口72から外周方向に向って高圧な圧縮空気Ａを噴射するから、
圧縮空気Ａが掘削孔151周囲に当たり、土粒子間の間隙水を外側に押し退けることができる。
【００４３】
また、このように本実施例では、請求項３に対応して、請求項１又は２記載の地盤改良工法に用いられ、二重管51の下端が略角錐状をなすから、その角錐形状の下端を砕石153に食い込ませて回転することにより、食い込んだ部分の砕石153を外側に押す力が発生し、これにより砕石153を効果的に締め固めることができる。また、下端に向って細くなる略角錐形状であるから、砕石153に圧入し易くなる。
【００４４】
また、実施例上の効果として、二重管51の下端に圧縮水Ｗを噴射する圧縮水用ノズル56と圧縮空気Ａを噴射する圧縮空気用ノズル57とを設け、それらノズル56，57から圧縮水Ｗと圧縮空気Ａとを噴射して地中に所定深さまで打ち込んで、掘削孔151を形成し、圧縮水Ｗと圧縮空気Ａとの噴射により地中の微細粒子を二重管51に沿って上昇させると共に、地表面152に排出し、この微細粒子を排出した後、圧縮空気Ａの噴射を停止又は噴射圧を下げ、二重管51を引き抜くと共に、この引き抜き時に掘削孔151内に中詰め材たる砕石153を投入する地盤改良装置において、自走式車両１に、リーダ５と、このリーダ５に沿って昇降可能に設けられた杭挟持体22と、中詰め材たる砕石153を収納する収納部31と、この収納部31の砕石153を掘削孔151に投入する投入装置35とを設けたから、自走式車両１により施工位置まで移動し、二重管51を杭挟持体22により挟持し、該杭挟持体22をリーダ５に沿って下降して二重管51を圧入し、この圧入時に、下方に向かって噴射した圧縮空気Ａと圧縮水Ｗとにより、下方の掘削孔151において、土粒子（土塊）の攪拌が行われ、圧縮空気Ａが泡となって上昇する際に土粒子を揺動して分解が行われ、これにより分解した微細粒子たる水溶性微細粒子が上昇水流と泡の上昇に伴うリフトアップ効果によりに地表面152に効率よく排土される。そして、杭挟持体22をリーダ５に沿って上昇することにより、二重管51を引き抜き、この引き抜き時に、自走式車両１の収納部31に収納した砕石153を、
ベルトコンベア32より掘削孔151内に投入し、この掘削孔151内に投入した砕石153を圧縮水Ｗにより水締めして圧密柱を形成することができる。そして、砕石153を投入後は、砕石153が攪拌されない程度なら圧縮空気Ａの噴射を継続できるから、圧縮空気Ａの噴射圧を下げるようにしても同様に圧密柱を形成することができ、特に、掘削孔151の全てを砕石153による圧密石柱154にする場合に有効である。また、投入装置35は、投入口34側を低くして傾斜した投入路33と、この投入路33に中詰め材たる砕石153を送る送り装置たるベルトコンベア32とを備えるから、投入路33に砕石153を送ってやれば、傾斜した投入路33により、砕石153が投入口34から掘削孔151内に投入され、リーダ５が邪魔にならず直接掘削孔151に、車体２から砕石153を投入できる。また、リーダ５が起伏可能で且つ長さ方向に移動可能に自走式車両１に設けられているから、リーダ５を使用時には立て、収納時には倒すことにより、自走式車両１の移動が容易となる。また、リーダ５自体を長さ方向に移動することにより、二重管51を圧入・引き抜きできるから、その移動分だけリーダ５の長さを短くできる。
【００４５】
そして、自動式車両１は無限軌道３を備えるから、従来の固定式の装置に比べて、現場内を機械移動で自走でき、起動力を大幅にアップできる。また、自走式車両１は中詰め材を収納部31に搭載可能であるから、施工時にバックホーなどの投入装置を必要とせず、狭い場所でも効率よく、中詰め材を投入でき、且つ、リーダ５の下部まで伸びる投入路33により掘削孔151に確実に供給でき、中詰め材における材料の無駄もない。また、リーダ昇降手段たるスライドシリンダ15を備えるから、該スライドシリンダ15によりリーダ５を昇降することによっても杭を圧入・引き抜きできるから、その昇降分だけリーダ５の長さを短くでき、また、リーダ５の収納、すなわち図１の鎖線に示す位置では、スライドシリンダ15によりリーダ５を前後させることにより、収納状態のリーダ５を含めた車体２の長さを押えることができ、自走式車両１の移動が容易になる。
【００４６】
上記のことから以下のことが分かった。この工法では、薬品、固結材を使用せず、水と空気を利用するため、施工後、汚染やそれらの消費をすることなく、地盤改良を行うことができる。また、圧縮水供給装置たる高圧ポンプ61や圧縮空気供給装置たるエアーコンプレッサ64の能力や、これらによる圧力及び流量を調節することにより、掘削孔直径の選定と深さとを任意に設定し、地盤改良を行うことができ、一般に、圧縮空気Ａの圧力と流量を大きくすれば、掘削孔の直径を大きくすることができる。また、施工工程が単純であるから、施工スピードが速い。さらに、現状地層の締め固め土質として有効な土粒子を圧密して再利用するため、搬入土などの充填材料を節約できる。さらに、排土が少なく済む。
また、施工も全ての土質、土層の軟弱地盤に施工できる。さらに、充填材料は、砕石、砂利、砂のほかにも、コンクリートを砕いたコンクリート砕も使用でき、建築廃材の廃材利用が可能となり、材料費の安価となる。
【００４７】
図１８は本発明の第２実施例を示し、上記各実施例と同一部分に同一符号を付し、その詳細な説明を省略して詳述すると、この例では、二重管51には空気噴射口76を設けずに、
該二重管51の外面に空気噴出管171を一体に設け、この空気噴出管171は先端が閉塞し、この杭の一部を構成する空気噴出管171に、外側に空気を噴射する圧密用圧縮空気噴射口72Ａを設けている。そして、前記エアーコンプレッサ64と別個の圧縮空気供給手段によって地上より圧縮空気が送り込まれ、前記圧密用圧縮空気噴射口72Ａから圧密用の圧縮空気Ａが掘削孔151の内面に向って噴射され、このように圧縮空気用ノズル57から噴射する圧縮空気Ａと、圧密用圧縮空気噴射口72Ａから噴射する圧密用の圧縮空気Ａとを別々に制御することができる。
【００４８】
尚、本発明は上記実施例に限定されるものではなく本発明の要旨の範囲内において種々の変形実施が可能である。例えば、実施例ではロッドの先端が略三角錐のものを示したが、略四角錐でも、それ以上の略角錐であってもよい。また、中詰め材は砕石に限らず、砂利や砂でも良く、要は加重支持材料であれば良い。また、実施例では、二重管を用いたが、圧縮水と圧縮空気とをそれぞれ別の管により供給するようにしてもよい。また、走行手段は無限軌道に限らず車輪などでもよい。また、昇降手段も杭挟持体をリーダに沿って移動するものであれば各種のものを用いることができる。さらに、送り手段は、ベルトコンベアに限らず、スクリューコンベヤやプッシャなどもよい。
【００４９】
【発明の効果】
請求項１の地盤改良方法は、ロッドの下端に設けられ圧縮水を下方に噴射する圧縮水用ノズルと、前記ロッドの下端に設けられ圧縮空気を下方に噴射する圧縮空気用ノズルと、
前記ロッドの下端に設けられたスクリューと、前記ロッドに設けられ圧密用の圧縮空気を外周方向に噴射する圧密用圧縮空気噴射口と、前記ロッドを正逆回転駆動する回転駆動手段とを備えた地盤改良装置を用い、前記ロッドの下端から圧縮水と圧縮空気とを噴射して該ロッドを地中に所定深さまで押し込んで掘削孔を形成すると共に、前記噴射した圧縮水と圧縮空気とにより、前記掘削孔の水溶性微細粒子を地表面に排出し、前記ロッドを引き抜くと共に、この引き抜き時に前記掘削孔に中詰め材を充填する地盤改良工法であって、
前記スクリューの掘削方向回転と前記圧縮水の噴射と前記圧縮空気の下方及び外周方向への噴射を継続して前記ロッドを押し込み、水が浸透した透水層において前記ロッドの下端から高圧な前記圧密用の圧縮空気を噴射して該圧密用の圧縮空気を掘削孔周面の土粒子間に押し込み、該掘削孔周囲の土粒子間の間隙水を外側に押し退けて圧密し、前記ロッドの下端が計画深さに達する前に、加重支持土質に不向きな前記水溶性微細土粒子の排出が少なくなったら、前記圧縮水の噴射量を削減し、この後、前記スクリューを反掘削方向に回転しながら掘削孔の計画深さまで前記ロッドを押し込み、前記掘削孔の下方に圧密された部分を形成し、この掘削孔の圧密された部分の上に前記中詰め材を充填する方法であり、
加重支持土質に不向きな水溶性微細土粒子等を良好に排出することができ、充填した中詰め材により良好な支持力を得ることができる。
【００５０】
また、請求項２の地盤改良方法は、請求項１の発明において、前記透水層が地下水位より下方のピート層又は砂層である方法であり、加重支持土質に不向きな水溶性微細土粒子等を良好に排出することができ、充填した中詰め材により良好な支持力を得ることができる。
【００５１】
また、請求項３の地盤改良装置は、請求項１又は２記載の地盤改良工法に用いられ、前記ロッドの下端が略角錐状をなすものであり、加重支持土質に不向きな水溶性微細土粒子等を良好に排出することができ、充填した中詰め材により良好な支持力を得ることができる。
【図面の簡単な説明】
【図１】本発明の第１実施例を示す一部を切り欠いた装置の側面図である。
【図２】本発明の第１実施例を示す装置の正面図である。
【図３】本発明の第１実施例を示す装置の使用状態の断面図である。
【図４】本発明の第１実施例を示す一部を切り欠いたロッドの下端の側面図である。
【図５】本発明の第１実施例を示す両ノズルの断面図である。
【図６】本発明の第１実施例を示すロッドの下端の斜視図である。
【図７】本発明の第１実施例を説明する水槽における実験例の断面図であり、二重管の挿入前の状態を示す。
【図８】本発明の第１実施例を説明する水槽における実験例の断面図であり、二重管の挿入後の状態を示す。
【図９】本発明の第１実施例を示す工程を説明する断面図であり、掘削開始時を示す。
【図１０】本発明の第１実施例を示す工程を説明する断面図であり、スクリューを掘削方向に回転してロッドを押し込む工程を示す。
【図１１】本発明の第１実施例を示す工程を説明する断面図であり、ロッドの下端が地下水位より下部の透水層に達した状態を示す。
【図１２】本発明の第１実施例を示す工程を説明する断面図であり、圧密用の圧縮空気により掘削孔の周囲に陥没部が形成された状態を示す。
【図１３】本発明の第１実施例を示す工程を説明する断面図であり、スクリューを反掘削方向に回転しながらロッドを押し込む状態を示す。
【図１４】本発明の第１実施例を示す工程を説明する断面図であり、ロッドの下端が設計深さに達した状態を示す。
【図１５】本発明の第１実施例を示すロッド引き上げ時の工程を説明する断面図であり、
スクリューを反掘削方向に回転しながら中詰め材を圧密する状態を示す。
【図１６】本発明の第１実施例を示すロッド引き上げ時の工程を説明する断面図であり、
スクリューを反掘削方向に回転しながら中詰め材の上面にロッドの下端を押し込んで中詰め材を圧密する状態を示す。
【図１７】本発明の第１実施例を示す圧密石柱の断面図である。
【図１８】本発明の第２実施例を示す一部を切り欠いたロッドの下端の側面図である。
【符号の説明】
24 回転駆動手段
51 二重管（ロッド）
56 圧縮水用ノズル
57 圧縮空気用ノズル
71 スクリュー
72，72Ａ 圧密用圧縮空気噴射口
82 角錐型外周面
151 掘削孔
151Ｎ 内壁部
152 地表面
153 砕石（中詰め材）
161 透水層
163 圧密された部分
Ｗ 圧縮水
Ａ 圧縮空気[0001]
[Technical field to which the invention belongs]
  The present invention relates to a ground improvement method and a ground improvement device.
[0002]
[Problems to be solved by the invention]
  Conventionally, as a method of using a filler in this kind of ground improvement method, Japanese Patent Application Laid-Open No. 56-52219 discloses that an injection pipe having an all-around horizontal jet head is inserted at a predetermined depth in sandy ground, Improvement of sandy ground where water or air is sprayed horizontally into the sandy ground through the all-around horizontal jet head to move and shrink the soil particles, and filler is injected into the voids created by the moving shrinkage and solidified. A construction method (Patent Claim) is proposed, and pressure water or pressure air is sprayed horizontally,
It is intended to move and shrink the soil particles by impact with pressurized water or compressed air (Gazette column 8, lines 1 and 2). Material (publication 8 column 7th to 9th line) is used, and since the curing material is used in this way,
There is a problem that material costs are required. Further, in JP-A-7-252823, when a consolidated pile is formed in the ground by using both a high-pressure jet jet and mechanical stirring, the stirring is provided with a space in the longitudinal direction of the pipe inserted into the ground. A method for controlling the finished pile diameter (patent claims) using at least two nozzles for ejecting a high-pressure jet of solidified material or water and an air jet covering the periphery of the high-pressure jet provided on the wing has been proposed. This method also uses cement milk, mortar, chemicals, etc. (construction method, column 4, lines 1 and 2) as the curing material, and thus has a problem that the material cost is high.
[0003]
  Therefore, as a method for improving the ground without using a hardener as described above, Japanese Patent Application Laid-Open No. 3-281815 discloses a vibro flot in the ground by vibration of the vibration part and jet water jet from the tip part. Penetration and pulling out while inserting stuffing material such as crushed stone and gravel,
A construction method is described in which the surrounding ground is compacted and a column of filling material is formed in the ground (Gazette page 1, right column, line 17 to page 2, upper right column, line 1). The vibration compaction device penetrates into the ground by the vibration of the vibration portion and the injection of the first compressed air from the tip of the vibration portion to form a perforation, and at the same time, the second compression from the outer periphery of the vibration compaction device A step of widening and holding the outer peripheral gap by the action of air injection and a flat plate provided in the axial direction of the rod portion; and after forming the perforations, the filling material is inserted into the gap while pulling out the vibration compaction device. There has been proposed a vibration compacting method (publication claims) comprising a process of charging.
[0004]
  In the method of jetting jet water described in JP-A-3-281815, muddy water is discharged to the ground surface by jet water, and water-soluble fine soil particles and the like in the ground are discharged together with the muddy water. It is a component contained in corrosive soil, etc., and is not suitable as a load-supporting soil, so that strength cannot be obtained even after compaction. However, simply jetting jet water cannot efficiently discharge components unsuitable for compaction, such as the water-soluble fine soil particles. Further, in the method of compacting by the compressed air injection and vibration as in the above-described vibration compaction method, the compaction is limited and the ground around the filling material cannot be compacted efficiently.
[0005]
  Therefore, the same applicant is disclosed in80638In this publication, a compressed water nozzle for injecting compressed water and a compressed air nozzle for injecting compressed air are provided at the lower end of the pile, and the compressed water and compressed air are injected from these nozzles to a predetermined depth in the ground. Driving and forming a drilling hole, raising fine particles in the ground along the pile by jetting the compressed water and compressed air,
After discharging to the ground surface and discharging these fine particles, stop the injection of compressed air or lower the injection pressure, pull out the pile, and propose a ground improvement method to insert the filling material into the excavation hole at the time of this extraction According to this ground improvement, the compressed air and the compressed water jetted downward are used to agitate the soil particles (clumps) in the excavation hole below the steel sheet pile, and the compressed air is As it rises, the soil particles are rocked and decomposed, and the decomposed water-soluble fine particles are efficiently discharged to the surface due to the lift-up effect associated with the rising water flow and rising bubbles. The And the filling material thrown into the excavation hole can be consolidated with compressed water to form a consolidated column.
[0006]
  JP 2000-80638IssueNewsIn this ground improvement method, by using compressed water and compressed air, a hardener or the like is unnecessary, and water-soluble fine soil particles and the like unsuitable for the load supporting soil can be discharged well. However, even with this ground improvement method, simply increasing the pressure of compressed water does not provide any further effect. Conversely, if the amount of compressed water used can be reduced, the construction cost can be reduced.
[0007]
  Therefore, the present invention eliminates the need for a hardener, can effectively discharge water-soluble fine soil particles, etc. unsuitable for the load-supporting soil, and can improve the ground that can obtain a good support force by the filled filling material It aims at providing a construction method and a ground improvement device.
[0008]
[Means for Solving the Problems]
  The ground improvement method of Claim 1 is provided in the lower end of a rod, and the nozzle for compressed water which injects compressed water below,SaidA nozzle for compressed air that is provided at the lower end of the rod and injects compressed air downward;
A screw provided at the lower end of the rod, and compressed air provided at the rod for compaction.In the outer circumferential directionCompression for injectionairAn injection port and a rotation driving means for driving the rod to rotate forward and backward are provided.Using the ground improvement device,Compressed water and compressed air are sprayed from the lower end of the rod and the rod is pushed into the ground to a predetermined depth to form a drilling holeIn addition, the water-soluble fine particles in the excavation hole are discharged to the ground surface by the jetted compressed water and compressed air, and the rod is pulled out.Ground improvement method that fills borehole with filling materialBecause
Rotation of the screw in the excavation direction, injection of the compressed water and injection of the compressed air in the downward and outer circumferential directions push the rod, and the lower end of the rod in the permeable layer into which water has permeated. The compressed air for compaction is injected from the high pressure to push the compressed air for compaction between the soil particles on the peripheral surface of the excavation hole, and the pore water between the soil particles around the excavation hole is pushed outward to be compacted,Before the lower end of the rod reaches the planned depthWhen the discharge of the water-soluble fine soil particles unsuitable for the load-supporting soil is reduced, the injection amount of the compressed water is reduced.While rotating the screw in the anti-digging directionTo the planned depth of the drilling holePush the rodForming a consolidated portion below the borehole and filling the filling material on the consolidated portion of the boreholeIs the method.
[0009]
  According to the structure of the first aspect, the injected compressed water and compressed air stir the soil particles (the lump) in the excavation hole below the rod, and the soil particles are rocked and decomposed. As a result, the water-soluble fine particles, which are fine particles decomposed, are efficiently discharged to the ground due to the lift-up effect associated with the rising water flow. Then, by pushing the rod while rotating the screw in the anti-excavation direction, the lower part of the rod is consolidated, and the lower part of the excavation hole formed to a predetermined depth becomes a consolidated part, and the filling material is inserted into the excavation hole. A high supporting pressure is obtained by the column portion filled with the filling material and the consolidated portion below it. Thus, since the compaction by rotation of the screw in the anti-excavation direction is used, the amount of compressed water used for compaction can be reduced or unnecessary.
[0010]
  In addition, high-pressure compressed air is injected into the water-permeable permeable layer, and the compressed air expands explosively in the excavation hole, and pore water (contained between the soil particles) between the soil particles around the excavation hole. Then, the portion where the pore water is pushed away becomes a settlement consolidated state due to the upper ground load.
[0011]
  Also, Claims2The ground improvement method according to claim 1 is the method according to claim 1, wherein the permeable layer is a peat layer or a sand layer below the groundwater level.
[0012]
  This claim2According to the configuration, in particular, in the peat layer or the sand layer below the groundwater level, the compressed air is more likely to enter between the soil particles around the excavation hole, and the consolidation effect around the excavation hole. Is obtained.
[0013]
  Also,Claim3The ground improvement device ofUsed in the ground improvement method according to claim 1 or 2,The lower end of the rod has a substantially pyramid shape.
[0014]
  This claim3According to the configuration, when the lower end of the substantially pyramid shape bites into the filling material and rotates, a force is generated that pushes the filling material into the filling material, thereby effectively tightening the filling material. Can be hardened.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 16 show a first embodiment of the present invention, and the ground improvement device used in this ground improvement method is shown in FIGS. The endless track 3 is a means, and the endless track 3 is driven by a prime mover (not shown) mounted on the vehicle body 2. A blade 4 as an excavator is provided at the rear portion of the vehicle body 2, and the blade 4 is provided so as to be driven up and down.
[0016]
  Further, a leader 5 is provided at the front portion of the vehicle body 2 so that the leader 5 can be raised and lowered. The leader 5 is moved to a storage position shown by a chain line in FIG. It can be undulated. Actually, the upper portion of the reader 5 can be tilted forward by about 5 degrees. The hoisting device 6 is provided with a lower portion of the hoisting base 7 on the vehicle body 2 so as to be able to hoist in the front-rear direction by a pivoting portion 8, and below the pivoting portion 8, the lower portion of the hoisting cylinder 10 by the pivoting portion 9. The telescopic rod 10A of the hoisting cylinder 10 is pivotally attached to the upper part of the hoisting base 7 by the pivoting portion 11. The hoisting cylinder 10 is a longitudinal angle adjusting means for the reader 5. A swing base 12 is provided on the front side of the undulation base 7 so as to be swingable in the left-right direction, and the undulation base 7 and the upper part of the swing base 12 are rotatably provided by a pivoting portion 13. The lower portion of the swing base 12 is provided so as to be movable left and right by the left and right slide drive mechanism 14. The left / right slide drive mechanism 14 is the left / right direction angle adjusting means of the reader 5. Also,
The reader 5 is provided at the front portion of the swing base 12 so as to be movable in the vertical direction, and the reader 5 is provided so as to be lifted and lowered with respect to the swing base 12 by a slide cylinder 15 serving as a reader lifting / lowering means. Accordingly, the reader 5 is moved to the working position in the storage position shown by the chain line in FIG. 1, and the undulation cylinder 10 is extended so that the leader 5 is substantially perpendicular to the ground in the front-rear direction. Thus, the lower part of the reader 5 is rotated left and right around the pivotal attachment part 13 so as to be substantially vertical in the left-right direction. Thereafter, the height position of the reader 5 can be adjusted by the slide cylinder 15. The cylinders 10 and 15 and the left / right slide drive mechanism 14 are driven by hydraulic pressure or the like.
[0017]
  A guide rail 21 is provided at the front portion of the leader 5, and a rod holding body 22 is provided along the guide rail 21 so as to be movable up and down. The rod holding body 22 is attached to the reader 5 by lifting means 23 having a chain. Go up and down along. The rod sandwiching body 22 is capable of sandwiching and releasing the sandwiched rod, and incorporates a rotation driving means 24 for rotating the sandwiched rod. Also,
A rod fixing means 25 is fixedly provided at the lower part of the reader 5, and the rod fixing means 25 is
The rod inserted therethrough can be clamped and released.
[0018]
  A hopper-like storage portion 31 is provided on the vehicle body 2, and filling material is stored in the storage portion 31, and a belt conveyor 32 serving as a feeding device is provided at the bottom of the storage portion 31. Is to send the filling material from the back to the front. On the terminal side of the belt conveyor 32, the storage portion 31 is provided with a charging path 33, and the charging path 33 is inclined so that the charging port 34 on the front end side is lowered,
The insertion port 34 extends to the lower part of the reader 5 in the standing position. In addition, wall portions 33A are provided on both sides of the charging path 33. And, by the belt conveyor 32 and the input path 33,
When the filling material is charged, a charging device 35 is configured.
[0019]
  41 is a hopper provided in the upper part of the excavation hole, and is provided with an enlarged cylinder part 43 in the upper part of the cylinder part.
[0020]
  In this example, as shown in FIG. 4 and FIG. 5, the rod is a double pipe 51 composed of a pipe, and this double pipe 51 is composed of an outer pipe 52 and an inner pipe 53. A compressed water channel 54 is formed in the tube 53, a compressed air channel 55 is formed between the inner surface of the outer tube 52 and the outer surface of the inner tube 53, and a compressed water nozzle 56 is provided at the lower end of the compressed water channel 54, A compressed air nozzle 57 is provided at the lower end of the air passage 55. Further, a water hose adapter 58 that communicates with the compressed water passage 54 and an air hose adapter 59 that communicates with the compressed air passage 55 are provided at the upper end of the double pipe 51.
A high pressure pump 61 as a compressed water supply device is connected to the water hose adapter 58 via a high pressure hose 60. The high pressure pump 61 is connected to a water tank 62. The water tank 62 is connected to a plurality of domestic waterworks. Store the water. Further, an air compressor 64 as a compressed air supply device is connected to the air hose adapter 59 via a hose 63. The double tube 51 can be adjusted in length by exchanging the central portion in the length direction.
[0021]
  As shown in FIG. 4 and the like, a screw 71 which is a spiral blade is provided at the lower end of the double pipe 51. In addition, a compression water injection port 72 for consolidation is provided at the lower end of the double pipe 51, and compressed air A for consolidation is injected from the compression water injection port 72 for compression in the outer circumferential direction.
[0022]
  As shown in FIG. 5, the compressed water nozzle 56 is screwed into the inner pipe 53, and an injection port 81 is formed at the lower end (tip). Further, the compressed water nozzle 56 is formed with a pyramid-shaped outer peripheral surface 82 that shrinks downward, and in this example, as shown in FIG.CornerThe conical outer peripheral surface 82 has a substantially truncated triangular pyramid shape having a corner 82A. A female screw portion 52A is formed on the inner surface of the lower end of the outer tube 52, and a male screw portion 57A that is screwed into the female screw portion 52A is formed on the outer surface of the upper end of the compressed air nozzle 57. Further, a tapered inner peripheral surface 84 is formed at the upper end (base end) of the compressed air nozzle 57, and the compressed air nozzle 57 is screwed into the outer tube 52,Pyramid typeA tapered guide air passage 85 communicating with the compressed air passage 55 is formed between the outer peripheral surface 82 and the tapered inner peripheral surface 84, and the compressed air passes through the center of the compressed air nozzle 57 by the guide air passage 85. Guided to the side. Further, a passage 87 extending from the guide air passage 85 to the injection port 86 at the lower end of the compressed air nozzle 57 is formed inside the compressed air nozzle 57. The length between the guide air passage 85 and the injection port 86 of the compressed air nozzle 57 is the injection port.86It is formed longer than the diameter D. The nozzle for compressed water56Injection port81The diameter d of the compressed air nozzle57Injection port56It is formed smaller than the diameter D. Further, the sectional area of the guide air passage 85 is set to be equal to or larger than the sectional area of the compressed air passage 55.
[0023]
  Experimental example 1
  This experimental example 1 is an example of examining the case where the present invention is applied to a plurality of soil layers, and in the transparent water tank 91, clay 92, fine sand 93, medium sand 94, coarse sand 95, and small gravel 96 are sequentially arranged from the lower layer. Spread layer 97 to form.
[0024]
  As shown in FIGS. 7 and 8, a double pipe 103 composed of an inner pipe 101 and an outer pipe 102 is formed, and compressed water is supplied from the tip of the inner pipe 101 and compressed air is supplied from between the inner pipe 101 and the outer pipe 102. Allow injection. When the tip of the double pipe 103 is inserted almost vertically into the layer 97 while jetting compressed air and compressed water, a flask-shaped excavation hole is formed below the double pipe 103, and the double pipe 103 In the flask-shaped excavation hole 98, the soil particles are stirred, and the insertion of the compressed air and the compressed water is continued.
This stirring decomposes the soil particle component. That is, if it is a layer of sand, it decomposes into a sand body and water-soluble fine soil particles contained therein. The water-soluble fine soil particles having a low specific gravity are discharged to the ground together with water by the rising water flow along the outer periphery of the double pipe 103 and the lift-up effect accompanying the rising of the compressed air. Check the soil discharge status on the ground, actually check the turbidity of the water discharged to the ground, and when the water-soluble fine soil particles are almost completely discharged, stop the jet of compressed air and use only compressed water. Continue jetting. When the supply of compressed air is stopped in this way, the stirring force in the flask-shaped excavation hole is reduced, and the soil particles are sequentially volumed to the bottom of the excavation hole from the soil particles having a large specific gravity that is not stirred by the compressed air. The soil particles are tightened by compressed water jetted downward, accumulated without gaps, and gradually pulled out of the double pipe 103 while continuing the jet of compressed water. Been formed.
[0025]
  Then, when the double pipe 103 is pulled out, the upper part of the excavation hole 98 becomes hollow by the volume of the water-soluble fine particles discharged and the compacted soil particles, and the filling material to be filled in this portion is Necessary.
[0026]
  From this experiment, it was found that high-pressure jet water was sprayed onto a plurality of soil volume formations to decompose soil particles, and further, stirring was possible by supplying compressed water and compressed air to the decomposed soil particles. In addition, water-soluble fine particles having a low specific gravity are well discharged to the ground due to the ascending force of compressed water containing air. Further, when the jet of compressed air is stopped and only the compressed water is jetted, the stirring force decreases, and the heavy soil particles that are not affected by the stirring force are sequentially deposited by the force of only the compressed water. The completed soil particle pillars became small gravel 96, coarse sand 95, medium sand 94, fine sand 93, and clay 92 from the bottom.
[0027]
  Experimental example 2
  In the transparent water tank 91, clay 92, fine sand 93, medium sand 94, coarse sand 95, and small gravel 96 were mixed and spread, and the experiment was conducted using the double pipe 103 as in Experiment Example 1. As in Experimental Example 1, the completed soil particle columns became small gravel 96, coarse sand 95, medium sand 94, fine sand 93, and clay 92 from the bottom.
[0028]
  In this way, it was found that even if the soil conditions and soil layer deposition conditions were changed, the resulting soil particle pillars were consolidated from the ones with heavy specific gravity.
[0029]
  Furthermore, from other experiments in which the injection pressures of compressed water and compressed air were changed with respect to Experimental Examples 1 and 2 above,
I found the following.
[0030]
  First, even in experiments with different soil conditions, those having heavy specific gravity accumulate from the bottom in the excavation hole 98. Moreover, sand can also be discharged if it adjusts so that the injection pressure of compressed water may be raised. In particular, only water-soluble fine soil particles that are inappropriate as load-bearing soil can be discharged arbitrarily by adjusting the injection pressure of compressed water and compressed air, and soil particles that are effective as load-bearing soil contained in the current ground By using and compacting the soil particles, a solid soil particle column can be made.
[0031]
  Next, a construction example will be described with reference to FIGS. 3 and 9 to 16. The self-propelled vehicle 1 moves to the construction position, extends the hoisting cylinder 10 and aligns the leader 5 substantially vertically,
With the left / right slide drive mechanism 14, the lower part of the reader 5 is rotated left and right around the pivoting portion 13 so as to be substantially vertical in the left / right direction, and thereafter the height position of the reader 5 can be adjusted by the slide cylinder 15. Therefore, even if the position of the self-propelled vehicle 1 is inclined, the excavation hole 151 can be excavated by adjusting the leader 5 in a predetermined direction. A hopper 41 is set at the excavation position. First, the lower end of the double pipe 51 is passed through the hopper 41 as shown in FIG.surfaceThe rod fixing means 25 is in the unlocked state andDescendThe rod holding body 22 is lowered by the step 23 to press-fit the double pipe 51, and the rotational driving meanstwenty fourThe double pipe 51 is rotated by the above. In this case, the double pipe 51 is rotated in the excavation direction, which is the direction in which the screw 71 bites in the pushing direction, and at the same time, the compressed water W is jetted downward. In the excavation hole 151 below the double pipe 51, the soil particle stirring action is generated by the compressed water W and the compressed air A, and the existing soil particle structure (soil lump) is decomposed and decomposed by the stirring action. The water-soluble fine soil particles having a light specific gravity are discharged along the outer surface of the double pipe 51 along the outer surface of the double pipe 51 together with the water by the rising water flow and the air lift-up action. Degradation of particle structure (soil lump) is done well. In this way, rotation of the screw 71 in the excavating direction and compressed waterWThe double pipe 51 can be pushed in efficiently by excavation by jetting. When the double pipe 51 is pressed into the ground by excavation in this way, the rotation of the screw 71 in the excavation direction and the injection of the compressed water W are continued, but this time the compressed air nozzle 57 and the compressed air injection port The compressed air A is jetted downward and outward from 72, and excavation with the compressed water W and the compressed air A is performed as shown in FIG. As shown in FIG. 11, when the lower end of the double pipe 51 reaches below the groundwater level H of the permeable layer 161, the compressed air injected from the compression compressed air injection port 72 toward the inner wall portion 151 N of the excavation hole 151. A expands in the excavation hole 151 and enters between the soil particles of the inner wall portion 151N to push away the interstitial water (water contained between the soil particles) between the soil particles. As shown, the portion where the interstitial water is pushed out becomes a subsidence-consolidated state due to the upper ground load, and a concavity 162 is formed in a mortar shape around the double pipe 51 on the ground surface 152. In addition, a peat layer or a sand layer is mentioned as a water-permeable layer. In this case, stop the rotation of the screw 71,
You may make it inject the compressed air A from the compressed air injection port 72 for compaction directly to the inner wall part 151N. From FIG. 12, the rotation of the screw 71 in the excavation direction, the injection of the compressed water W, and the downward and outward injection of the compressed air A are continued to push the double pipe 51 and the excavation is continued. And if discharge | emission of the water-soluble fine soil particle unsuitable for a load supporting soil becomes small, the injection amount of the compressed water W will be reduced. Thereafter, as shown in FIG. 13, by pressing the double pipe 51 while rotating the screw 71 in the anti-excavation direction, a compacted portion 163 is formed below the double pipe 51, as shown in FIG. Thus, the double pipe 51 is pushed down to the planned depth (deepest part) of the excavation hole 151. Thus, before reaching the bottom of the excavation hole 151, the rotation of the double pipe 51 is changed in the reverse direction and the screw 71 is rotated in the anti-excavation direction to reduce the injection pressure of the compressed water W or the compressed water W Is stopped and the double pipe 51 is pushed downward, so that the lower part of the double pipe 51 is consolidated, and a consolidated part 163 is formed below the excavation hole 151 formed to a predetermined depth.
[0032]
  Further, in excavation, the screw 71 is used, and the lump of soil is decomposed by the stirring action accompanying the rotation of the screw 71. Further, by excavating the screw 71, the excavation hole 151 having a uniform cylindrical shape can be formed. In the pressing operation of the double pipe 51, when the rod holding body 22 is lowered to the lowest position, the holding by the rod holding body 22 is released, and the double pipe 51 is held and fixed by the rod fixing means 25. Is lifted up and down to the top of the reader 5, the double tube 51 is held by the rod holding body 22, the holding of the double tube 51 by the rod fixing means 25 is released, and the rod holding means 22 is lowered again. The double pipe 51 can be pushed in. Furthermore, the slide cylinder 15 serving as the reader lifting / lowering means allows the reader to5The double pipe 51 can be press-fitted and pulled out by moving up and down.
[0033]
  Next, description will be given of the filling operation of the filling material when the double pipe 51 is pulled up. As described above, the double pipe 51 is pushed to the planned depth (deepest part) while rotating the screw 71 in the anti-excavation direction. By drilling holes151A compacted portion 163 is formed below. Up to its design depth (deepest part)soAfter excavation, the injection of compressed air A is stopped or a small amount of injection is continued. Then, as shown in FIG. 3, the crushed stone 153 as the filling material is stored in the storage portion 31 of the vehicle body 2,
At the time of charging, the belt conveyor 32 is driven to supply the crushed stone 153 from the charging port 34 to the opening 151A of the excavation hole 151 in accordance with the settlement speed of the crushed stone 153. In this case, the supply amount of the crushed stone 153 can be adjusted by adjusting the driving speed of the belt conveyor 32. Then, in the state where the rotation of the screw 71 in the anti-excavation direction is continued, as shown in FIG. 14, the crushed stone 153 is supplied, and the crushed stone 153 supplied into the excavation hole 151 follows the outer periphery of the double pipe 151. It settles down and deposits on the consolidated part 163 of the excavation hole 151. The screw 71 is consolidated with crushed stone 153 deposited in the anti-excavation direction.
Further, as shown in FIGS. 15 and 16, the double pipe 51 is pulled up while moving up and down in accordance with the input of the crushed stone 153, that is, in accordance with the height of the upper surface 153A of the crushed stone 153 in the excavation hole 151. . In this case, the upper surface of the crushed stone is moved by the vertical movement of the double pipe 51.153The height of A is confirmed, the elevating means 23 is driven, and the lower end of the double pipe 51 is pushed downward from the crushed stone upper surface 153A as shown in FIG.CornerThe cone-shaped outer peripheral surface 82 is pushed into the crushed stone 153, and further, the tip of the pyramid shape is rotated to generate a force to push the surrounding crushed stone 153 outward, thereby compacting the crushed stone 153 and surrounding the crushed stone. The inner wall 151N of the excavation hole 151 is compacted. At this time, if the lower end of the double pipe 51 hits the crushed stone upper surface 153A, the downward pressing force of the rod clamping body 22 changes, so that the hit position can be confirmed by the device of the self-propelled vehicle 1. For example, a means for measuring the reaction force applied from the double pipe 51 to the lifting means 23 that lifts and lowers the rod clamping body 22 can be provided. And as an example, if the double pipe 51 is pulled up by a predetermined length, for example, about 60 cm while thrown the crushed stone 153, it is moved downward several times at a predetermined stroke S, for example, 1 m stroke S at this position. Move up and down and rotateCornerThe conical outer peripheral surface 82 is compacted so as to be pressed downward from the crushed stone upper surface 153A. In this case, it rotates into the crushed stone 153CornerBy pressing the conical outer peripheral surface 82 downward from the crushed stone upper surface 153A, this pressure input acts as a compacting force (indicated by arrow Y in FIG. 16) of the surrounding soil.
[0034]
  Then, the above-described steps are repeated, and the double pipe 51 is gradually pulled up to form a compacted stone column 154 made of crushed stone 153 supplied by almost all of the excavation hole 151 as shown in FIG.
[0035]
  The soil particles that can be consolidated in the ground may be used as part of the compacted column without being discharged on the ground surface 152.
[0036]
  This method can arbitrarily set the depth of the support pile, that is, if the depth of the support pile does not reach the support layer, crushed stone can be supplied to form the support pile. In addition, it is possible to remove only soil particles that are unsuitable as the load-bearing soil quality of the current geological formation, and it is possible to consolidate and reuse the appropriate soil particles as compaction soil contained in the current geological formation. . Furthermore, as the filling material can use solid particles such as crushed stone, gravel, sand, and concrete crushed concrete, which can be consolidated, it is possible to reuse construction waste by using concrete crushed. Become. Since the material to be used in this way is inexpensive and it is not necessary to use a special device, the construction cost is also low. In addition, since water and air are used, no medicine or the like is required.
Further, when the double pipe 51 is pulled out, the double pipe 51 is moved up and down, and the crushed stone 153 in the excavation hole 151 is struck by the double pipe 51. The crushed stone 153 is consolidated, and the soil around the crushed stone 153 can be compacted. Further, since the method of reducing the injection pressure of the compressed water W after discharging the fine particles, by reducing the injection pressure of the compressed water W, soil particles that can be consolidated in the ground are discharged to the ground surface 152. Therefore, the soil particles can be compacted to form a consolidated column in the excavation hole 151, and the material cost of the crushed stone 153 and the like can be reduced. Moreover, in the method of injecting the compressed water W and the compressed air A at the same time,
Since the compressed water nozzle 56 is provided above the compressed air nozzle 57, the compressed air A having a lower pressure than the compressed water W can be injected well. The compressed water W injected from the compressed water nozzle 56 is injected outside through the central side of the passage 87 in the compressed air nozzle 57 because the injection port 81 is thinner than the compressed air nozzle 57. At the same time, compressed air A flows into the passage 87 from the compressed air passage 55 through the guide air passage 45, and this compressed air A is guided to the central side of the passage 87 by the tapered compressed air passage 85 and flows through this central side. Compressed waterWAnd a part thereof are efficiently mixed, and the surrounding compressed air A is pulled by the flow of the compressed water W and is injected from the injection port 86 of the compressed air nozzle 57 and efficiently supplied to the bottom of the excavation hole 151. Is done.
[0038]
  Thus, in this embodiment, corresponding to claim 1, the nozzle 56 for compressed water provided at the lower end of the double pipe 51 serving as a rod and jetting the compressed water W downward, and the lower end of the double pipe 51 are provided. Compressed water nozzle 57 that injects compressed air A downward, screw 71 provided at the lower end of double pipe 51, and compression for compression that is provided in double pipe 51 and injects compressed air A for compaction.airIt has an injection port 72 and a rotation drive means 24 for driving the double pipe 51 to rotate forward and backward.Using ground improvement equipment,Compressed water W and compressed air A are injected from the lower end of the double pipe 51 and pushed into the ground to a predetermined depth to form a drilling hole 151.And at the same time, the injected compressed water W and compressed air A 151 The water-soluble fine particles of the ground 152 To discharge and double pipe 51 At the time of pulling outGround improvement method to fill digging hole 151 with crushed stone 153 as filling materialAnd screw 71 Rotation in the excavation direction, injection of compressed water W and injection of compressed air A downward and outer peripheral direction 51 Permeable layer with water 161 In double pipe 51 The compressed air A for high-pressure consolidation is jetted from the lower end of the nozzle and the compressed air A for consolidation is drilled. 151 The excavation hole is pushed between the surrounding soil particles. 151 Consolidate by pushing away the interstitial water between surrounding soil particles to the outside,Before the lower end of the double pipe 51 reaches the planned depthWhen the discharge of water-soluble fine soil particles unsuitable for the load-supporting soil is reduced, the injection amount of the compressed water W is reduced.While rotating the screw 71 in the anti-digging directionDrilling hole 151 Up to the planned depthPush double pipe 51, Drilling holes 151 The part consolidated below 163 Forming this drilling hole 151 The consolidated part of 163 Crushed stone on top 153 FillingFrom the jetted compressed water W and compressed air A, the soil particles (soil mass) are stirred in the excavation hole 151 below the double pipe 51, and the soil particles are shaken and decomposed. Water-soluble fine particles, which are fine particles decomposed by the above, are efficiently discharged to the ground due to the lift-up effect associated with the rising water flow. Then, by pushing the double pipe 51 while rotating the screw 71 in the anti-excavation direction, the lower part of the double pipe 51 is consolidated, and the lower part of the excavation hole 151 formed to a predetermined depth becomes a consolidated part 163, The excavation hole 151 is filled with crushed stone 153, and a high support pressure is obtained by the pillar portion formed by the crushed stone 153 and the consolidated portion below the pillar portion. In this way, since compression by rotation of the screw 71 in the anti-excavation direction is used, compressed water necessary for consolidation is used.WCan be used or reduced.
[0039]
  Also,Thus, in this embodiment, the claims1In response toin frontDuring the indentation, high-pressure compressed air A is injected from the lower end of the double pipe 51 as a rod in the water permeable layer 161 into which water has permeated, and the compressed air A is pushed between the soil particles on the circumferential surface of the excavation hole 151, Since the interstitial water between the soil particles around the hole 151 is pushed outward and consolidated, high pressure compressed air A is injected into the water permeable layer 161 in which water has permeated, and the compressed air A explodes in the excavation hole 151. Inflated and between soil particles around drilling hole 151ofThe pore water (water contained between the soil particles) is pushed outward, and the portion where the pore water is pushed away becomes a subsidence-consolidated state due to the upper ground load, and in the permeable layer 161 having a high groundwater level H, A compacted stone pillar 154 with consolidated layers can be obtained.
[0040]
  In this way, in this embodiment, the claims2Correspondingly, the permeable layer 161 is a peat layer or a sand layer below the groundwater level H.151Easy to penetrate between surrounding soil particles, excavation hole151A consolidation effect in the surroundings can be obtained.
[0041]
  Also, BA compressed water nozzle 56 that is provided at the lower end of the double pipe 51 that is a jet pipe and that injects the compressed water W downward; The screw 71 provided at the lower end of the double pipe 51 and the compression for compression that is provided in the double pipe 51 and injects compressed air A for compaction.airSince the injection port 72 and the rotation drive means 24 for rotating the double pipe 51 forward and backward are provided, the compressed water W and the compressed air A jetted downward are used in the excavation hole 151 below the double pipe 51. The soil particles (clumps) are agitated, the soil particles are rocked and decomposed, and the water-soluble fine particles, which are decomposed fine particles, are efficiently discharged to the ground due to the lift-up effect associated with the rising water flow. Is done. Further, by using the jet of the compressed air A and the rotation of the screw 71 in combination, the soil particles are effectively decomposed by the stirring by the bubbles of the compressed air A and the rotation of the screw 71. Then, in the water-permeable layer 161 into which water has permeated, compression for compactionairHigh-pressure compressed air A is injected from the injection port 72, and the compressed air A explosively expands in the excavation hole 151, and between the soil particles around the excavation hole 151.ofThe pore water (water contained between the soil particles) is pushed out to the outside, and thereafter, the portion where the pore water is pushed away can be brought into a settlement consolidated state by the upper ground load.
[0042]
  Also, PressureSince high-pressure compressed air A is injected from the dense compressed water injection port 72 toward the outer peripheral direction,
The compressed air A hits around the excavation hole 151, and the interstitial water between the soil particles can be pushed outward.
[0043]
  In this way, in this embodiment, the claims3In response toUsed in the ground improvement method according to claim 1 or 2,Since the lower end of the double pipe 51 forms a substantially pyramid shape, the lower end of the pyramid shape bites into the crushed stone 153 and rotates to generate a force that pushes the crushed stone 153 of the bited portion outward. Can be effectively compacted. Further, since it has a substantially pyramid shape that narrows toward the lower end, it is easy to press-fit into the crushed stone 153.
[0044]
  Further, as an effect of the embodiment, a compressed water nozzle 56 that injects compressed water W to the lower end of the double pipe 51 and compressed air.AA compressed air nozzle 57 that injects compressed water W and compressed air A from the nozzles 56 and 57 and is driven into the ground to a predetermined depth to form an excavation hole 151; The fine particles in the ground are raised along the double pipe 51 by jetting with the compressed air A and discharged to the ground surface 152. After the fine particles are discharged, the compressed airAStop the injection or lower the injection pressure, pull out the double pipe 51, and at the time of pulling out the drilling hole151In the ground improvement device in which the crushed stone 153 as the filling material is put inside, the self-propelled vehicle 1 has the leader 5, the pile sandwiching body 22 that can be moved up and down along the leader 5, and the crushed stone as the filling material. Since the storage unit 31 for storing 153 and the input device 35 for inputting the crushed stone 153 of the storage unit 31 into the excavation hole 151 are provided, the self-propelled vehicle 1 moves to the construction position and clamps the double pipe 51 The pile 22 is lowered along the leader 5 to press-fit the double pipe 51, and at the time of the press-fitting, the compressed air A and the compressed water W jetted downward are used to lower the pile. In the excavation hole 151, the agitation of the soil particles (the lump) is performed, and the compressed airAWhen the soil rises in the form of bubbles, the soil particles are rocked and decomposed, and the water-soluble fine particles, which are the decomposed fine particles, are brought to the ground surface 152 due to the rising water flow and the lift-up effect accompanying the rising of the bubbles. It is efficiently discharged. Then, by lifting the pile sandwiching body 22 along the leader 5, the double pipe 51 is pulled out, and at this time, the crushed stone 153 stored in the storage unit 31 of the self-propelled vehicle 1 is
It is possible to form a compacted column by putting it into the excavation hole 151 from the belt conveyor 32 and water-tightening the crushed stone 153 introduced into the excavation hole 151 with the compressed water W. Then, after the crushed stone 153 is introduced, the compressed air A can be continuously injected as long as the crushed stone 153 is not agitated. Therefore, even if the injection pressure of the compressed air A is reduced, a compacted column can be formed in particular. This is effective when all of the excavation holes 151 are consolidated stone columns 154 by the crushed stone 153. In addition, the charging device 35 includes a charging channel 33 that is inclined with the charging port 34 side lowered, and a belt conveyor 32 that is a feeding device that feeds the crushed stone 153 that is the filling material to the charging channel 33. If the crushed stone 153 is sent, the crushed stone 153 is thrown into the digging hole 151 through the inlet 34 by the inclined feeding path 33, and the crushed stone 153 is thrown into the digging hole 151 directly from the vehicle body 2 without getting in the way. it can. Further, since the leader 5 is provided in the self-propelled vehicle 1 so as to be able to undulate and move in the length direction, the self-propelled vehicle 1 can be easily moved by standing the leader 5 when it is in use and tilting it when it is stored. It becomes. Further, since the double pipe 51 can be press-fitted and pulled out by moving the reader 5 itself in the length direction, the length of the reader 5 can be shortened by the amount of the movement.
[0045]
  And since the automatic vehicle 1 is equipped with the endless track 3, compared with the conventional fixed-type apparatus, it can carry out self-propelled by the machine movement in the spot, and can improve starting force significantly. Moreover, since the self-propelled vehicle 1 can mount the filling material in the storage portion 31, it does not require a charging device such as a backhoe at the time of construction, and can efficiently insert the filling material even in a narrow place. 5 can be reliably supplied to the excavation hole 151 by the input path 33 extending to the lower part of the No. 5, and there is no waste of material in the filling material. In addition, since the slide cylinder 15 serving as the leader lifting / lowering means is provided, the pile can be press-fitted / pulled out by raising / lowering the leader 5 by the slide cylinder 15, so that the length of the leader 5 can be shortened by the raising / lowering amount. 5, that is, in the position indicated by the chain line in FIG. 1, the length of the vehicle body 2 including the leader 5 in the stored state can be suppressed by moving the leader 5 back and forth by the slide cylinder 15. Easy to move.
[0046]
  From the above, the following was found. Since this method uses water and air without using chemicals or caking materials, the ground can be improved after construction without contaminating or consuming them. In addition, by adjusting the capacity and pressure and flow rate of the high-pressure pump 61 as a compressed water supply device and the air compressor 64 as a compressed air supply device, the selection and depth of the drilling hole diameter can be arbitrarily set to improve the ground. In general, compressed air AofIf the pressure and flow rate are increased, the diameter of the borehole can be increased. Moreover, since the construction process is simple, the construction speed is fast. Furthermore, since the soil particles that are effective as compaction soil for the current formation are consolidated and reused, it is possible to save filling materials such as incoming soil. In addition, less soil is required.
In addition, construction can be performed on all soil types and soft ground. In addition to the crushed stone, gravel, and sand, the crushed concrete can be crushed concrete, making it possible to use the waste of building waste and reducing the material cost.
[0047]
  FIG. 18 shows a second embodiment of the present invention. The same reference numerals are given to the same parts as those of the above-described embodiments, and the detailed description thereof is omitted. Without providing the injection port 76,
An air jet pipe 171 is integrally provided on the outer surface of the double pipe 51. The air jet pipe 171 is closed at the tip, and is used for compaction to inject air to the air jet pipe 171 constituting a part of the pile. A compressed air injection port 72A is provided. Then, compressed air is sent from the ground by compressed air supply means separate from the air compressor 64, and compressed air A for compaction is jetted from the compressed compressed air injection port 72A toward the inner surface of the excavation hole 151. Thus, the compressed air A injected from the compressed air nozzle 57 and the compressed compressed air A injected from the compressed air injection port 72A can be controlled separately.
[0048]
  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention. For example, in the embodiment, the tip of the rod has a substantially triangular pyramid, but it may be a substantially quadrangular pyramid or a larger pyramid. In addition, the filling material is not limited to crushed stone, but may be gravel or sand. Moreover, although the double pipe was used in the Example, you may make it supply compressed water and compressed air with a respectively separate pipe | tube. The traveling means is not limited to an endless track, and may be a wheel. Various lifting / lowering means may be used as long as they move the pile holding body along the leader. Further, the feeding means is not limited to a belt conveyor, and may be a screw conveyor or a pusher.
[0049]
【The invention's effect】
  The ground improvement method of Claim 1 is provided in the lower end of a rod, and the nozzle for compressed water which injects compressed water below,SaidA nozzle for compressed air that is provided at the lower end of the rod and injects compressed air downward;
A screw provided at the lower end of the rod, and compressed air provided at the rod for compaction.In the outer circumferential directionCompression for injectionairAn injection port and a rotation driving means for driving the rod to rotate forward and backward are provided.Using the ground improvement device,Compressed water and compressed air are sprayed from the lower end of the rod and the rod is pushed into the ground to a predetermined depth to form a drilling holeIn addition, the water-soluble fine particles in the excavation hole are discharged to the ground surface by the jetted compressed water and compressed air, and the rod is pulled out.Ground improvement method that fills borehole with filling materialBecause
Rotation of the screw in the excavation direction, injection of the compressed water, and injection of the compressed air in the downward and outer circumferential directions push the rod into the water-permeable water-permeable layer from the lower end of the rod for high-pressure consolidation. The compressed air for compression is pushed between the soil particles around the borehole, and the pore water between the soil particles around the borehole is pushed outwards to be consolidated,Before the lower end of the rod reaches the planned depthWhen the discharge of the water-soluble fine soil particles unsuitable for the load-supporting soil is reduced, the injection amount of the compressed water is reduced.While rotating the screw in the anti-digging directionTo the planned depth of the drilling holePush the rodForming a consolidated portion below the borehole and filling the filling material on the consolidated portion of the boreholeIs the way
Water-soluble fine soil particles and the like unsuitable for the weighted support soil can be discharged well, and a good support force can be obtained by the filled filling material.
[0050]
  Also, Claims2The ground improvement method according to claim 1 is the method according to claim 1, wherein the permeable layer is a peat layer or a sand layer below the groundwater level, and the water-soluble fine soil particles unsuitable for the load-supporting soil are discharged well. And a good supporting force can be obtained by the filled filling material.
[0051]
  Claims3The ground improvement device ofUsed in the ground improvement method according to claim 1 or 2,The lower end of the rod has a substantially pyramid shape, and water-soluble fine soil particles unsuitable for the load-supporting soil can be discharged well, and a good supporting force can be obtained by the filled filling material. .
[Brief description of the drawings]
FIG. 1 is a side view of a partially cut-out apparatus showing a first embodiment of the present invention.
FIG. 2 is a front view of the apparatus showing the first embodiment of the present invention.
FIG. 3 is a sectional view of the apparatus in use according to the first embodiment of the present invention.
FIG. 4 is a side view of the lower end of a rod with a part cut away, showing a first embodiment of the present invention.
FIG. 5 is a sectional view of both nozzles showing a first embodiment of the present invention.
FIG. 6 is a perspective view of the lower end of the rod showing the first embodiment of the present invention.
FIG. 7 is a cross-sectional view of an experimental example in a water tank for explaining the first embodiment of the present invention, showing a state before insertion of a double pipe.
FIG. 8 is a cross-sectional view of an experimental example in a water tank for explaining the first embodiment of the present invention, showing a state after the double pipe is inserted.
FIG. 9 is a cross-sectional view for explaining the steps of the first embodiment of the present invention, showing the start of excavation.
FIG. 10 is a cross-sectional view for explaining the steps of the first embodiment of the present invention, showing the step of pushing the rod by rotating the screw in the excavation direction.
FIG. 11 is a cross-sectional view for explaining the steps of the first embodiment of the present invention, showing a state where the lower end of the rod has reached the water permeable layer below the groundwater level.
FIG. 12 is a cross-sectional view for explaining the steps of the first embodiment of the present invention, showing a state in which a depression is formed around the excavation hole by the compressed air for consolidation.
FIG. 13 is a cross-sectional view for explaining the steps of the first embodiment of the present invention, showing a state in which the rod is pushed in while rotating the screw in the anti-excavation direction.
FIG. 14 is a cross-sectional view for explaining the steps of the first embodiment of the present invention, showing a state in which the lower end of the rod has reached the design depth.
FIG. 15 is a cross-sectional view for explaining a process for lifting the rod according to the first embodiment of the present invention;
A state in which the filling material is consolidated while rotating the screw in the anti-excavation direction is shown.
FIG. 16 is a cross-sectional view for explaining a process for lifting the rod according to the first embodiment of the present invention;
A state in which the lower end of the rod is pushed into the upper surface of the filling material while the screw is rotated in the anti-excavation direction to compact the filling material.
FIG. 17 is a cross-sectional view of a compacted stone pillar showing a first embodiment of the present invention.
FIG. 18 is a side view of the lower end of a rod with a part cut away, showing a second embodiment of the present invention.
[Explanation of symbols]
24 Rotation drive means
51 Double pipe (rod)
56 Nozzle for compressed water
57 Compressed air nozzle
71 screw
72, 72A Compressed compressed air injection port
82 Pyramidal outer peripheral surface
151 drilling holes
151N inner wall
152 Ground surface
153 Crushed stone (filled material)
161  Permeable layer
163 Consolidated part
W Compressed water
A Compressed air

Claims (3)

ロッドの下端に設けられ圧縮水を下方に噴射する圧縮水用ノズルと、
前記ロッドの下端に設けられ圧縮空気を下方に噴射する圧縮空気用ノズルと、前記ロッドの下端に設けられたスクリューと、前記ロッドに設けられ圧密用の圧縮空気を外周方向に噴射する圧密用圧縮空気噴射口と、前記ロッドを正逆回転駆動する回転駆動手段とを備えた地盤改良装置を用い、前記ロッドの下端から圧縮水と圧縮空気とを噴射して該ロッドを地中に所定深さまで押し込んで掘削孔を形成すると共に、前記噴射した圧縮水と圧縮空気とにより、前記掘削孔の水溶性微細粒子を地表面に排出し、前記ロッドを引き抜くと共に、この引き抜き時に前記掘削孔に中詰め材を充填する地盤改良工法であって、前記スクリューの掘削方向回転と前記圧縮水の噴射と前記圧縮空気の下方及び外周方向への噴射を継続して前記ロッドを押し込み、水が浸透した透水層において前記ロッドの下端から高圧な前記圧密用の圧縮空気を噴射して該圧密用の圧縮空気を掘削孔周面の土粒子間に押し込み、該掘削孔周囲の土粒子間の間隙水を外側に押し退けて圧密し、前記ロッドの下端が計画深さに達する前に、加重支持土質に不向きな前記水溶性微細土粒子の排出が少なくなったら、前記圧縮水の噴射量を削減し、この後、前記スクリューを反掘削方向に回転しながら掘削孔の計画深さまで前記ロッドを押し込み、前記掘削孔の下方に圧密された部分を形成し、この掘削孔の圧密された部分の上に前記中詰め材を充填することを特徴とする地盤改良工法。A nozzle for compressed water that is provided at the lower end of the rod and injects compressed water downward;
A nozzle for compressed air that injects compressed air provided at the lower end of the rod downward, a screw provided at a lower end of the rod, compression compaction that injects compressed air for compaction provided to the rod in the outer circumferential direction Using a ground improvement device provided with an air injection port and a rotation driving means for driving the rod to rotate forward and reverse , compressed water and compressed air are injected from the lower end of the rod to the ground to a predetermined depth. It is pushed in to form a drilling hole, and with the jetted compressed water and compressed air, the water-soluble fine particles of the drilling hole are discharged to the ground surface, the rod is pulled out, and the drilling hole is filled at the time of this pulling a soil improvement method of filling the timber, pushing the rod to continue injection of the compressed water injection and drilling direction rotation of the screw downwardly and the outer peripheral direction of the compressed air In the permeable layer in which water has permeated, high-pressure compressed air for compaction is injected from the lower end of the rod, and the compressed compressed air is pushed between the soil particles on the peripheral surface of the excavation hole. When the discharge of the water-soluble fine soil particles unsuitable for the load-supporting soil is reduced before the lower end of the rod reaches the planned depth , the injection amount of the compressed water is reduced. After that, the rod is pushed to the planned depth of the drilling hole while rotating the screw in the anti-excavation direction to form a consolidated portion below the drilling hole. A ground improvement method characterized by filling the filling material above . 前記透水層が地下水位より下方のピート層又は砂層であることを特徴とする請求項１記載の地盤改良工法。Ground improvement method according to claim 1, wherein said water permeable layer is a peat or sand below the groundwater level. 請求項１又は２記載の地盤改良工法に用いられ、前記ロッドの下端が略角錐状をなすことを特徴とする地盤改良装置。 A ground improvement device used in the ground improvement method according to claim 1 or 2, wherein a lower end of the rod has a substantially pyramid shape .
JP2001307143A 2001-10-03 2001-10-03 Ground improvement method and ground improvement equipment Expired - Lifetime JP3757415B2 (en)

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JP4566634B2 (en) * 2004-07-02 2010-10-20 清治 折戸 Ground improvement method
JP2007056605A (en) * 2005-08-26 2007-03-08 Asahi Kasei Construction Materials Co Ltd Liquefaction preventing method
JP4709073B2 (en) * 2006-06-05 2011-06-22 旭化成建材株式会社 Ground improvement method
KR200481281Y1 (en) * 2015-01-15 2016-09-07 (주)광진 Digging equipment for grounding construction
JP6905816B2 (en) * 2016-11-07 2021-07-21 株式会社不動テトラ Displacement-reducing compaction sand pile construction hollow pipe and compaction sand pile construction method
CN107813747A (en) * 2017-11-28 2018-03-20 佛山科学技术学院 A kind of tipper with compression function of municipal works
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