JP3711094B2

JP3711094B2 - Ground reinforcement method

Info

Publication number: JP3711094B2
Application number: JP2002212129A
Authority: JP
Inventors: 拓治山本; 健介伊達; 徹羽馬; 秀明林
Original assignee: Kajima Corp
Current assignee: Kajima Corp
Priority date: 2002-07-22
Filing date: 2002-07-22
Publication date: 2005-10-26
Anticipated expiration: 2022-07-22
Also published as: JP2004052393A

Description

【０００１】
【発明の属する技術分野】
本発明は、主としてトンネル構築時に坑内から地山を注入により補強する地山補強工法に関する。
【０００２】
【従来の技術】
従来、地質条件の悪い地山等でトンネルを掘削する際には、前方地山を補強しながらトンネルを掘り進めることが行われている。例えば、前方地山を補強しながらトンネルを掘削する場合などに適用する地山補強工法の１つとして、掘削に先立って切羽鏡部から前方地山のトンネル外周に地山補強体である長尺の先受け材をトンネル周方向にアーチ状に配置して切羽前方地山を補強する長尺先受け工法がある。又この長尺先受け工法には、先受け材として鋼管等の管材を用い、その管材の内空およびその周囲の地山内に固結材を注入して固化させる注入式の長尺先受け工法があり、この工法は山岳トンネル工法に使用する油圧ドリルジャンボなど標準的な掘削機械設備を用いて簡単に施工できる利点がある。
【０００３】
上記のような注入式長尺先受け工法は、例えば削孔ロッドの先端に装着した拡径ビット、もしくは削孔ロッドの先端に装着したインナービットと鋼管等の管材の先端部に設けたリングビットとによる二重管方式で、各ビットに回転と打撃を伝達しながら地山内に削孔を施すと同時に、その削孔内に、周面に吐出孔を有する直径１００ｍｍ程度の孔あき鋼管等よりなる管材を順次継ぎ足しながら所定長さの補強管を所定の仰角で打設する。
【０００４】
この場合、トンネル掘削時の天端部の剥落防止と切羽前方地山の拘束力を高めるためには上記の仰角をなるべく小さくするのが望ましく、そのため、上記補強管を打設する切羽鏡部の手前６ｍ程度のトンネル断面を拡幅することによって、上記補強管を最小限の仰角で打設できるようにすると共に、トンネル掘削時には、その内周面に布設される支保工と上記補強管との離れが最小限になるようにしている。
【０００５】
図９は上記のようにトンネル掘削断面を拡幅しながら施工する従来の注入式長尺先受け工法の一例を示すもので、トンネル空間３内において切羽鏡部１ａから地山１内に長尺の鋼管よりなる補強管６が打設されている。その補強管６は、鏡吹付コンクリート２が設けられた切羽鏡部１ａに於ける拡幅鋼製支保工４ｂの内側から、後に建て込まれる切羽前方の鋼製支保工４ｂ’の背面へ最小限の離れで、かつ先受け効果を発揮させるためトンネル空間３から５度程度の仰角Ｔをつけて前方地山１内に打設されている。
【０００６】
上記の仰角Ｔを維持するためには、ドリルジャンボ等の削岩機のガイドセル長分に相当する６ｍ程度の断面拡幅区間Ｓを設け、切羽鏡部１ａの直近に既に建て込まれた鋼製支保工４ｂの下端を定規として所定の間隔でトンネル周方向に全長に亘って補強管を順次打設するのが本工法の特徴である。
【０００７】
また上記のようにして打設された長尺の補強管を介してその周囲の地山内に固結材を注入固化させて地山を補強するもので、その固結材としては、例えばセメント系またはレジン系の固結材を用いる。その固結材を補強管の口元からバルブ等を介して注入もしくは隔壁を設けた分割注入を行い、先受け工としての長尺の補強管と固結材による補強管周囲の固結領域（定着領域）の形成により、先受け拘束効果を発揮させるものである。
【０００８】
また、最近では上記のようにトンネル掘削断面を拡幅しないで施工する無拡幅タイプの注入式長尺先受け工法が用いられている。図１０はそのような無拡幅タイプの従来の注入式長尺先受け工法の一例を示すもので、トンネル断面を拡幅することなく掘削したトンネル空間３の切羽鏡部１ａから前方地山１内に鋼管等の補強管６を所定の仰角で打設し、次にトンネルを掘削して支保工４ｂを建て込む際には、その掘削断面外周線から切羽鏡部に位置する区間Ｌにおける補強管６の後端部６ｂを切除するものである。
【０００９】
そのため、上記補強管６の少なくとも後端部６ｂ側は、トンネル掘削時に容易に切除できるように、例えばトンネル掘進長に合わせた複数本の短管を分離容易なジョイント手段等を介して互いに切除可能に連結したもの、あるいは鋼管等の管材に予めスリットを入れて切除可能に構成したもの、もしくは塩化ビニール管などの合成樹脂管等が用いられる。
【００１０】
上記補強管６の後端部６ｂは、切羽前方に建て込まれる支保工４ｂの３〜６ｍ程度の範囲内に位置するようにして地山内に埋設し、トンネル掘削時には、その掘進に伴って地山から露出した部分を順次切除して支保工を建て込んでいくものである。
【００１１】
なお上記のようにして地山内に打設した補強管６内およびその周囲の地山内には固結材Ｇを注入して補強管６の周囲に固結領域８を形成するもので、その固結材Ｇは補強管６内に直接注入するか、あるいは補強管内にインナー管等の注入管を挿入して注入する。その注入管としては、例えば塩化ビニール管または合成樹脂製のインナー管等を用いる。そして上記注入管を介してセメント系もしくはレジン系の固結材Ｇを補強管６内に注入することにより、該補強管６が打設された地山１の孔壁との間の空隙内に固結材Ｇを充填して補強管６と前記地山孔壁とを定着させると共に、補強管６の周囲の地山内に固結材Ｇを注入することによって、岩片あるいは土粒子間の結合力を高めると共に、補強管６の周囲に固結領域８を形成することで切羽前方地山の拘束効果を高めるものである。
【００１２】
上記工法に於いて固結材Ｇを注入する例としては、例えば図１１に示すセメント系注入方式がある。本例では補強管６内に塩化ビニール管等の注入管１０が収容され、該注入管１０に排気管１１が一本添設されており、補強管６の端部開口部はゴム栓１５ａとストッパー１５で止め、注入管１０には注入バルブ１４を介して注入ホース１４ａが接続されている。また鏡面吹付コンクリート２と補強管６の後端部外周面との間には口元コーキング等のシール材２５が施され、注入ホース１４ａからセメント系固結材Ｇを注入し、補強管６を挿入した削孔ｈの孔壁との間の空隙ｓ内に充填して定着させると共に、周囲の地山１内に固結材Ｇを注入して固結領域８を形成するものである。
【００１３】
以上の工法は様々な地山条件に対応でき長尺先受けが可能なため、地山の先行変位の抑制、地山の緩みの防止、施工の安全性確保等を目的に長尺先受け工法として用いられている。
【００１４】
ところが、上記のような地山先受け工法が要求される地山は元来脆弱であることに加えて、切羽鏡部近傍の地山は掘削に伴うゆるみが生じている。例えば図１２（ａ）は数値解析により切羽周辺の挙動を示したもので、比較的広い領域Ｒで挙動があり、図で色の濃い領域ほど挙動が大きい。図中のｄは切除区間である。図に示すように、脆弱な地山状況における施工時の切羽挙動と同様に、解析的にも脆弱かつ押出し挙動の存在していることが確認できる。
【００１５】
そこで、天端崩落防止および切羽安定性確保、または地山変形の軽減のため、図９、図１２に示すような先受け工や切羽鏡部補強が実施されてきたが、図９、図１２(ｂ)に示す先受け工を施工しても鋼管の間からの地山の抜け落ち、鋼管の下方地山の剥落、改良領域の形成不足による地山変状および地表沈下増大などのトラブルが依然として多く、また図１２(ｃ)に示す切羽鏡部補強を施工した場合でも、切羽崩落、押出し挙動の発生、切羽先の地表面沈下増大などのトラブルが起こっているのが現状である。特に図１２（ｂ）に示す無拡幅工法の長尺鋼管先受けにおいては、切羽天端部の切羽天端部の既補強管とトンネル掘削外周線に位置する薄層の区間の地山は剥落が生じやすい。
【００１６】
これらは、既補強管の下部に削孔時のスライムが堆積していること、補強管自体が孔壁下部に密着していることから、加圧注入のみの注入材による固結領域は補強管の上方部のみに形成され下方部には注入材が廻り難く、既補強管と改良地山からなる改良領域が確保されないことが一因である。また、定圧注入した場合は細やかな間隙や亀裂に一旦生じた目づまりが解消されず、粗い間隙や亀裂に集中して注入され易く、鋼管周囲にコラム状に計画される所定の均質な改良体ではなく、ある方向に卓越した形で注入されたような不均質な改良体や脈状の改良になってしまうこともまた一因であると考えられる。
【００１７】
すなわち、トンネルの先受け工法や切羽補強で一般的に行われている従来の定圧注入では、計画したよりも不均質な改良体が主に鋼管上部に形成され、適正な地山補強効果を得られない結果、地山変状や地表面沈下を効果的に防止できず、また鋼管間の地山抜け落ち，鋼管下部の薄層の崩落、切羽崩落といったトラブルを引き起こしていることが多く見受けられる。
【００１８】
【発明が解決しようとする課題】
本発明は上記問題点に鑑みなされたものであって、先受け工若しくは切羽鏡部補強工等の地山補強工法において、例えばトンネル掘削時の解放応力である押出し挙動に伴って、トンネル掘削断面から打設した補強管の位置する領域の地山が、セメント系若しくはレジン系等の固結材で補強管周囲の定着および改良不足から発生する剥落およびゆるみの漸増を抑制し、均一性の高い注入補強効果を発揮できると共にトンネル掘削作業時に追加補強を行う必要がなく、適格な地山補強効果を得ることができ、多様な掘削方式に於いて低コストで施工することができる地山補強工法を提供することを目的とする。
【００１９】
【課題を解決するための手段】
上記の目的を達成するために本発明による地山補強工法は、以下の構成としたものである。即ち、周面に吐出孔を有する所定長さの補強管を地山内に打設し、該補強管内に固結材を注入して該補強管内およびその周囲の地山内に固結材を浸透させて地山内に固結領域を形成する地山補強工法に於いて、上記補強管内に棒鋼等の棒状体を収容配置し、上記補強管内に固結材を注入する際に、上記棒状体の端部付近に振動を付与して該棒状体を介して上記固結材または上記補強管もしくは両者に振動を伝達させながら上記補強管内に固結材を注入することを特徴とする。
【００２０】
また本発明による地山補強工法は、周面に吐出孔を有する所定長さの補強管を地山内に打設し、該補強管内に固結材を注入して該補強管内およびその周囲の地山内に固結材を浸透させて地山内に固結領域を形成する地山補強工法に於いて、上記補強管内に固結材を注入するための注入管またはインナー管を収容配置し、上記補強管内に固結材を注入する際に、上記注入管またはインナー管の端部付近に振動を付与して該注入管またはインナー管を介して上記固結材または上記補強管もしくは両者に振動を伝達させながら上記補強管内に固結材を注入することを特徴とする。
【００２１】
上記の振動を付与する手段としては、高周波振動発生装置等の振動発生装置を用いるもので、その振動発生装置は上記棒状体の端部付近に直接取付けるか、あるいは別の任意の位置に配置して適宜の振動伝達手段で上記端部付近に振動を伝達するようにしてもよい。
【００２２】
前記のように補強管の下端および周囲に固結材の未定着領域および改良不足があると地山の拘束力が損なわれ、剥落若しくはゆるみの漸増挙動が生じ易く、該補強管の位置する領域が脆弱な地山で孔壁が自立しない状況や、補強管周囲に孔壁の崩壊若しくは削孔スライムの堆積および補強管下端が孔壁に密着した状況であっても、上記の構成により、固結材に振動を伝達させることによって補強管と孔壁の密着度は減り、スライムも振動により流動性を持つことで、該補強管下部で無効となっていた吐出孔が機能回復する。また、注入材は振動をかけることで励起され流動化が促進され、地山に固結材が注入され易くなる。
【００２３】
また、定圧注入に比べて振動注入は逆側の動きが入るため、走行し易い方向に注入材が逸走するのを軽減し、目づまりの発生を抑え、補強管の全周および全長にわたって万遍なく注入され、補強管の周囲に固結材による定着および改良領域を良好に形成することが可能となる。
【００２４】
その結果、例えばトンネル先受け工にあっては、補強管からトンネル掘削断面外周線までの剥落し易い薄層の地山は、該補強管と固結材による定着領域が確保され拘束力の増加により、トンネル掘削時における切羽鏡部の押出し挙動も抑制され、安定性が高まり合理的な補強が可能となる。また切羽鏡部補強工にあっては、切除が容易な合成樹脂管等の補強管を用いた場合にも、該補強管の周囲が全長に亘って固結材による定着領域が確実に形成され、切羽鏡部の大きな押し出し挙動に耐え得る所要の定着力を確保することが可能となる。
【００２５】
【発明の実施の形態】
以下、本発明による地山補強工法を図に示す実施形態に基づいて具体的に説明する。図１は本発明による地山補強工法を先受け工に適用した施工状態の縦断面図、図２はその横断面図、図３は一部の拡大縦断面図である。
【００２６】
図１〜図３に示すように構築中のトンネルでは、地山１の切羽鏡部１ａに吹付コンクリート２が施され、切羽鏡部１ａの後方では既に掘削が完了した状態で支保が形成されている。トンネル空間３には側壁及びアーチ部分の地山を覆うように吹付コンクリート４ａが施されており、その内側には鋼製の支保工４ｂがトンネルの横断面形状に沿った形で、トンネル掘進方向に例えば１ｍ毎など所定間隔毎に建て込まれている。
【００２７】
トンネル空間３の切羽鏡部１ａには、掘進作業に先立って施工された先受け工５が、図１のように掘進方向に所定間隔毎に設けられ、かつ図２のようにトンネル周方向にアーチ状をなすようにして地山１内に配設されている。その先受け工５は、トンネルの横断面形状に沿って所定ピッチで且つ掘進方向に所定間隔毎に打設された地山補強材としての補強管６と、注入管１０を介して補強管６内およびその周囲の地山１内に注入された固結材Ｇによる固結領域８と、その固結領域８の形成に先立って補強管周囲の切羽鏡部１ａ側に形成されるバルクヘッド領域７とで構成されている。
【００２８】
上記補強管６は、切羽鏡部１ａの外周から前方の地山１内に向かって所定の仰角で打設されている。また本実施形態においては、図１および図３に示すようにトンネル掘削断面を拡幅しないため、トンネル掘削時には、その掘削領域内に位置する図３で長さＬに対応した補強管６の後端部６ｂを切除する必要があり、上記の長さＬは、本実施形態においては約４ｍに設定されている。
【００２９】
そこで、本実施形態においては、上記補強管６の前部６ａを、互いに雌雄のねじ接合によって接続された複数本の比較的長い鋼管（以下、長管という）６１で構成し、補強管６の後端部６ｂは、易破壊性のカプラ等のジョイント手段６４で接続された比較的短い鋼管（以下、短管という）６２と、その短管６２の最後端部に接続したバルクヘッド領域形成用のラティス管６３とで構成している。
【００３０】
上記各管６１〜６３の寸法や接続本数等は適宜であるが、本実施形態においては、長管６１として内径（直径）１１４．３ｍｍ、長さ３ｍの鋼管が３本接続され、短管６２としては長管６１と同径で長さ１ｍの鋼管が３本、ラティス管６３としては長管６１と略同径で長さ１ｍの鋼線メッシュ構造のラティス管が１本それぞれ順に接続されている。
【００３１】
上記補強管６内には、図４に示すように補強管６内およびその周辺の地山内に固結材を注入するための注入管１０と、上記固結材を注入する際に補強管内等に残留する空気を排出するための排気管１１と、棒鋼等の棒状体１２と、バルクヘッド形成用のパッカー１３等が収容配置されている。
【００３２】
上記の注入管１０として、本実施形態においては外周面にロープネジを有する外径（直径）３０．５ｍｍ、長さ６ｍのＦＲＰ(Fiberglass Reinforced Plastics)製の管が用いられている。そのＦＲＰ製の注入管は、軸方向の力に対して強い特長があり、しかもトンネル掘削時には掘削刃等により容易に切除可能である。
【００３３】
また上記棒状体１２は振動を付与して該棒状体を介して固結材に振動を伝達させるもので、本実施形態においては直径１６ｍｍの棒鋼が用いられ、その棒状体１２は上記注入管１０に添わせて設けられている。上記棒状体１２は後述する固結材注入後も補強管６内に存置するか、あるいは固結材注入後に補強管６から引き抜き除去して繰り返し使用するようにしてもよい。また上記棒状体１２と排気管１１の長さ寸法は適宜であるが、本実施形態においては補強管６の先端付近までの長さに形成されている。
【００３４】
上記の注入管１０と排気管１１および棒状体１２は、所要の強度を有するものであれば材質や径寸法等は適宜であるが、後述する固結材注入後も補強管６内に存置する場合には、少なくともそれらの後端部側はトンネル掘削時に掘削刃等で容易に切除できる材質もしくは構成のものを用いるのが望ましく、例えば鋼材等のトンネル掘削時の掘削刃では容易に切除できない材質にあっては、所定単位長さ（例えば１ｍ程度）に切断したものを、トンネル掘削時の掘削刃等で容易に破壊可能な易破壊性のカプラ等のジョイント手段で複数本接続したものを用いるようにしてもよい。
【００３５】
さらに前記パッカー１３は、本実施形態においては、その膨張用の薬液の少なくとも一部が透過可能な布等で袋状に形成したもので、そのパッカー１３には該パッカー内に薬液を注入するためのナイロンチューブ等の注入チューブ１３ａが設けられている。
【００３６】
上記注入管１０と排気管１１および棒状体１２は、図４（ｂ）のように束ねた状態で、その周囲にパッカー１３を巻き付けて締結具で締め付け固定され一体化されており、それらを図４（ａ）のように補強管６内に挿入することによって上記パッカー１３がラティス管６３内に位置するように構成されている。図中、１５はラティス管６３の端部を閉塞するゴム栓１４を抑える逆止弁ストッパ、１６は注入バルブで、そのバルブ１６の一端を注入管１０に接続し、バルブ１６の他端に図に省略した注入ホース等を接続して、その注入ホースから上記注入バルブ１６および注入管１０を介して補強管６内に固結材を注入する構成である。
【００３７】
上記の構成において、トンネル空間３の切羽鏡部１ａの前方地山１内に先受け工５を施工するに当たっては、例えば以下の手順で施工する。
【００３８】
図５はその前段の施工手順を示すもので、先ず同図（ａ）のように切羽鏡部１ａの直前に建て込まれた支保工４ｂの下端の所定位置から前方地山１に向けて直径１６０ｍｍ、深さ３００ｍｍ程度の下孔ｈ１を削孔しておくと共に、図１のようにトンネル空間３に配置されたドリルジャンボ等の削岩機９のガイドセル９ａに補強管６を構成する長管６１を載置し、その長管６１の先端に設けられたケーシングシュー２０にリングビット２１を装着する。
【００３９】
また上記の長管６１内には、先端にインナービット２２が装着された削孔ロッド２３を挿入して、その削孔ロッド２３の後端をドリルジャンボ等の削岩機９のシャンクに連結し、削孔ロッド２３の先端のインナービット２２を介してリングビット２１に打撃力や回転力を伝達して削孔ｈを施すと同時に該削孔ｈ内に長管６１を挿入して行く。
【００４０】
なお削孔方式は適宜であり、上記のようにインナービット２２とリングビット２１とで削孔する方式の他に、例えば削孔ロッドの先端に拡縮可能な拡径ビットを装着して、それらを長管６１内に挿入し、上記拡径ビットを長管６１の先端部で拡開した状態で、該ビットに打撃力や回転力を伝達して削孔すると同時に長管６１を挿入するようにしてもよい。
【００４１】
また、その削孔時および長管６１の挿入時には、前記のガイドセル９ａを所定の仰角Ｔ、例えば３度から６度、好ましくは５度程度にセットし、下孔ｈ１から切羽鏡部１ａの前方に位置する地山１内に向け、前記のビットで削孔ｈを施しながら補強管６を打設する。
【００４２】
本実施形態では補強管６の前部６ａに長さ３ｍの長管６１を順次ねじ込み式に接続しながら３本打設した後、補強管６の後端部６ｂに長さ１ｍの３本の短管６２と１本のラティス管６３を打設する。なお長管６１の最後端と、上記の短管６２およびラティス管６３は、本実施形態においては、前述のように易破壊性のカプラ等のジョイント手段６４で順次接続する。
【００４３】
そして、これらの複数本の長管６１と短管６２およびラティス管６３とからなる所定長さの補強管６を上記削孔ｈ内に存置し、前記の削孔ロッド２３やインナービット２２等は引き抜いて回収する。また、補強管６と下孔ｈ１との間には、図５（ｂ）に示すように、ウエス等のシール材２５を充填して閉塞する。
【００４４】
この状態で、例えば前記の固結領域８を形成するための固結材Ｇとしてセメント系のものを用いる場合には、ゲルタイムが長いため注入時のバックプレッシャーによるリークを抑制するために、予め補強管６の後端部６ｂ側に図５（ｃ）に示すようにバルクヘッド領域７を形成する。
【００４５】
そのバルクヘッド領域７を形成する薬液Ｆとしては、例えばウレタン系薬液を用い、注入チューブ１３ａからパッカー１３内に注入すると、該パッカー１３内に薬液Ｆが充填されて該パッカー１３がラティス管６３内で膨らんで該ラティス管６３内の空間が閉塞されると共に、上記パッカー１３内に注入した薬液の一部が前記の削孔ｈ内およびその周囲の地山内に浸透して上記のバルクヘッド領域７が形成される。そのバルクヘッド領域７は、後述する固結領域８を形成するための固結材を補強管６内に注入する際に、該固結材が切羽鏡部１ａ側にリーク（漏洩）するのを防止するための隔壁として機能する。
【００４６】
上記のようにしてバルクヘッド領域７を形成したところで、図５（ｃ）に示すように注入管１０に注入バルブ１６を接続して、その注入バルブ１６および注入管１０を介して補強管６内に、固結領域８の形成用の固結材を注入するもので、そのとき本発明においては上記の固結材Ｇまたは補強管６もしくは両者に振動を伝達させながら上記の固結材を注入するものである。
【００４７】
その固結材Ｇまたは補強管６もしくは両者に振動を伝達させる手段として本実施形態においては図６に示すように高周波振動発生装置等の振動発生装置３０を用いたもので、その振動発生装置３０の設置位置は適宜であるが、図の場合は前記注入管１０に添設した棒状体１２の後端部付近に振動発生装置３０を取付けて、その棒状体１２および注入管１０を介して該注入管１０から補強管６内に注入される固結材Ｇまたは補強管６もしくは両者に振動を伝達するようにしたものである。
【００４８】
なお上記の振動発生装置３０には、該装置を所望の位置に容易に移動できるようにアダプターが組み込まれており、それによって任意の位置に容易に移動可能である。また上記の振動発生装置３０は、上記の棒状体１２の後端部付近以外の位置もしくは全く別の任意の位置に配置して適宜の振動伝達手段を介して上記後端部付近に振動を伝達するようにしてもよい。さらに上記のような振動を付与する手段としては、上記の構成に限られるものではなく、固結材Ｇまたは補強管６もしくは両者に振動を伝達させることができれば、適宜変更可能である。
【００４９】
上記のようにして固結材Ｇまたは補強管６もしくは両者に振動を伝達させながら固結材Ｇを注入することにより、補強管６の周囲にスライムまたは孔壁崩壊があり、あるいは補強管６の下端が孔壁に密着した状態でも、上記の振動により補強管６と孔壁との密着度が減り、スライムも振動により流動性を持つことで、補強管下部の閉塞状態になっていた吐出孔６１ａ，６２ａは機能回復し、固結材は補強管６を構成する長管６１および短管６２の周面に形成した吐出孔６１ａ、６２ａから振動を付与する固結材が励起され流動性が増して周辺地山１内にスムーズに吐出され、図７（ａ）のように切羽鏡部１ａの前方の補強管６の周囲に万遍なく定着および固結領域８を形成することができるものである。
【００５０】
特に上記の構成により、固結材は例えば単に加圧注入しただけでは周りにくい補強管６の下側の領域にも拡がり、後に掘削するトンネル掘削断面外周線と補強管６との間の剥落し易い薄層状の地山を良好に補強することができる。また、それによって、トンネル掘削時における鏡部の押出し挙動も抑制され、切羽天端部の安定性が高まり合理的な補強が可能となるものである。
【００５１】
また上記の補強管６およびバルクヘッド領域７と固結領域８とからなる上記先受け工５は、前述のようにトンネル内で切羽鏡部１ａの外周に沿ってアーチ状に施すもので、切羽鏡部１ａの外周にアーチ状の先受け工５を施工すると、その下側に位置する掘削予定の地山１の安定性が確保される。そして、図７（ｂ）に示すように更にトンネルを掘進して切羽鏡部１ａを前進し、切羽鏡部１ａが前進した分だけ順に支保工４ｂを建て込んでトンネルの掘進作業を進行する。
【００５２】
その際、直前に打設した先受け工５の補強管６の後端部６ｂが位置する地山１も掘削することになるが、掘進が例えば約１ｍ進んだところでは、図７（ｂ）に示すように、補強管６の後端部６ｂに設けられた本例では１ｍのラティス管６３が短管６２から分離して切除され、その際に注入管１０と棒状体１２も同時に切除される。
【００５３】
その後は、トンネル掘進の進行に伴って、易破壊性のカプラ等のジョイント手段６４を破壊し或いはジョイント手段６４から短管６２を脱落し、順次１ｍづつ短管６２を切除すると共に、注入管１０と棒状体１２をトンネル掘進に伴って切除していく。そして最終的には補強管６の前記後端部６ｂに位置する短管６２を全て分離除去すると共に、補強管６の後端部６ｂに位置する注入管１０と棒状体１２を切除するものである。
【００５４】
上記実施形態においては、トンネル掘進に伴ってトンネル掘削断面の拡幅を行なわないので、同一断面で支保工４ｂを順次建て込んで行くことができる。また補強管６の後端部６ｂは前述のようにトンネル掘削時に切除が容易な構造に構成されているので、補強管６のみではトンネル掘進時に生じる切羽鏡部１ａの大きな押し出し挙動等に対しては必ずしも充分な強度が得られない懸念があるが、ＧＦＲＰ製の注入管と固結材による定着領域との協働によって先受け工として本来必要な引張剛性を充分に確保することが可能となる。その結果、脆弱な地山状況においても切羽鏡部の安定性が損なわれることなく、先受け工としての軸力は適正に確保され、更に周辺地山１への固結材Ｇによる補強が確実に達成されて適切な固結領域８が形成されるので、地山の安定性は十分に確保される。従って、効率的に且つ安全にトンネル掘進作業を行うことができる。
【００５５】
なお上記本実施形態は、補強管６として、比較的長い鋼管（長管）６１と、比較的短い鋼管（短管）６２と、鋼線メッシュ構造のラティス管６３とで構成したが、それらの材質や連結構造等は適宜変更可能であり、例えば前記のバルクヘッド領域７を形成する必要がない場合には、ラティス管６３の代わりに鋼管や樹脂管等を用いてもよく、また補強管６全体を１本の管材で構成することもできる。
【００５６】
また上記実施形態においては、固結領域８を形成する固結材Ｇとして硬化時間が比較的長いセメント系固結材を用いたが、ウレタン、シリカレジン、無機複合ウレタンなどのウレタン系の固結材を使用することもできる。
【００５７】
さらに上記実施形態は、トンネル掘削断面を拡幅しないで先受け工を施工する場合を例にして説明したが、前記図９のようにトンネル掘削断面を拡幅して施工する場合にも適用可能である。
【００５８】
また本発明は、前記図１２（ｃ）に示すような切羽鏡部の補強工等にも適用可能であり、図８は上記のような切羽鏡部の補強工に適用した場合の施工状態の一例を示す要部の縦断面図である。
【００５９】
補強管６としては、本実施形態においては、外周面に固結材との付着性を増強する溝加工が施された外径７６ｍｍ、内径６０ｍｍ、長さ３ｍの複数本のＦＲＰ製チューブ６５を、互いにねじ接合によって順次接続すると共に、その最後部のチューブ６５にカプラ６４を介してバルクヘッド領域形成用のラティス管６３を接続した構成であり、上記補強管６は切羽鏡部１ａから前方の地山１に向けて、施工中の鏡部補強工５ａがリング状に設けられている。
【００６０】
なお上記振動発生装置３０は、前記図６と同様に棒状体１２（不図示）に取付けられている。他の構成は前記の実施形態と同様であり、同様の作用効果が得られる。
【００６１】
さらに本発明は、上記のようなトンネルの先受け工や切羽鏡部補強工に限らず他の各種の地山補強工法、例えば崖の法面等を補強する場合などにも適用可能であり、上記と同様の作用効果が得られる。
【００６２】
【実施例】
本発明の実施例として、前記図１〜図３に示すトンネル先受け工を想定し、前述のような構成部材を用いて、実際の現場での注入試験(1)として密な砂質地盤の場合と、注入試験(2)として粘性土地盤の場合とについて、それぞれ固結材の注入試験を行って地盤（地山）内への固結材の浸透状況を調べた。なお固結材としては、セメント系固結材を用い、振動発生装置３０としては、高周波振動発生装置を用い、前記図６のように棒状体１２の後端部付近に取付けて、周波数２００Ｈｚで棒状体１２を介して該補強管６内に順次注入している固結材に振動を伝達させた。
【００６３】
上記実施例に対する比較例として、上記振動発生装置３０による補強管６および固結材への振動を付与することなく、固結材を注入した以外は上記実施例と同様の条件で注入試験を行った。その結果を下記表１にまとめて示す。
【００６４】
【表１】

【００６５】
上記表１中にも記載したように、比較例においては、いずれの場合にも補強管の周方向全長にわたって放射方向への固結材の浸透量が少なく、特に補強管の下部には固結材の浸透が僅かに確認できる程度であったのに対し、本発明による実施例においては、いずれの場合にも補強管の周方向全長にわたって放射方向への固結材の定着領域が確保され、特に、注入試験▲１▼の密な砂質地盤の場合には、補強管の下部や側部でも１０ｃｍ以上の固結材の浸透による固結領域（改良領域）が得られることが分かった。また、注入試験▲２▼の粘性土地盤の場合においても、ある方向へ固結材が逸走するのを防ぎ、周方向全長にわたって放射方向に定着が得られ、より均等に地山を改良できることが確認できた。
【００６６】
【発明の効果】
以上説明したように本発明による地山補強工法は、地山内に打設した補強管内およびその周囲の地山内に固結材を注入する際に、該固結材または補強管もしくは両者に振動を伝達させるようにしたから、固結材の流動化が促進され、例えば補強管の下部に堆積するスライムおよび補強管が孔壁下部に密着した状況においても補強管の周方向全長にわたって、その周囲の地山内に固結材を良好に浸透させることが可能となり、未定着領域を可及的に低減することができる。特に、トンネル先受け工や鏡部補強工にあっては、トンネル掘削時の解放応力である押出し挙動に対し、セメント系もしくはレジン系等の固結材が有する強度を充分に発揮して補強管周囲の地山拘束効果を効率よく向上させることができる。また補強管周囲の定着不足から発生する剥落および鏡部の押出し挙動が抑制され、均一性の高い注入補強効果を発揮できる共に、トンネル掘削作業時に追加補強等を行う必要がないので、地山の対応性が広がり適格な地山補強効果を得ることができる。さらにトンネル掘削時の作業量とコストを大幅に減少でき、補助工法にかかる工期や施工費等を抑え、かつ作業の安全性を高めることができる等の効果がある。
【図面の簡単な説明】
【図１】本発明による地山補強工法の一実施形態を示す施工状態の縦断面図。
【図２】上記実施形態の横断面図。
【図３】上記実施形態の要部の拡大縦断面図。
【図４】上記実施形態に用いた補強材の構成説明図。
【図５】上記実施形態の前段の施工プロセスを示す工程説明図。
【図６】振動発生装置の配置構成を示す説明図。
【図７】上記実施形態の後段の施工プロセスを示す工程説明図。
【図８】本発明による地山補強工法を鏡部補強工に適用した例の要部の縦断面図。
【図９】従来の地山補強工法の一例を示す縦断面図。
【図１０】（ａ）は従来の地山補強工法の他の例を示す説明図。
（ｂ）はその横断面図。
【図１１】従来の地山補強工法における固結材の注入状態を示す縦断面図。
【図１２】（ａ）は従来の地山補強工法における固結材のリーク状態を示す説明図。
（ｂ）従来の地山補強工法の一例を示す縦断面図。
（ｃ）従来の地山補強工法の他の例を示す縦断面図。
【符号の説明】
１地山
１ａ切羽鏡部
２吹付コンクリート
３トンネル空間
４ａ吹付コンクリート
４ｂ支保工
５先受け工
６補強管
６１長管
６２短管
６１ａ、６２ａ吐出孔
６３ラティス管
６４カプラ
７バルクヘッド領域
８固結領域
９削岩機
１０注入管
１１抜気管
１２棒状体
１３パッカー
ｈ削孔
ｈ１下孔
Ｇ固結材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a natural ground reinforcement method for reinforcing a natural ground by injection from a pit when a tunnel is constructed.
[0002]
[Prior art]
Conventionally, when a tunnel is excavated in a natural ground having poor geological conditions, the tunnel is dug while reinforcing the natural ground ahead. For example, as one of the natural ground reinforcement methods applied when excavating a tunnel while reinforcing the front natural ground, a long length which is a natural ground reinforcement body from the face mirror part to the outer periphery of the front natural ground tunnel before excavation. There is a long tip receiving method in which the tip receiving material is arched in the circumferential direction of the tunnel to reinforce the ground in front of the face. In addition, in this long tip receiving method, a pipe material such as a steel pipe is used as a receiving material, and an injection type long tip receiving method in which a solidified material is injected and solidified in the inner space of the pipe material and in the surrounding ground. This method has the advantage that it can be easily constructed using standard drilling equipment such as a hydraulic drill jumbo used in the mountain tunnel method.
[0003]
The injection type long tip receiving method as described above is, for example, a diameter expanding bit attached to the tip of a drilling rod, or an inner bit attached to the tip of a drilling rod and a ring bit provided at the tip of a pipe material such as a steel pipe. With a double pipe method, drilling holes in the natural ground while transmitting rotation and blow to each bit, and at the same time, from a perforated steel pipe with a diameter of about 100 mm having discharge holes in the peripheral surface A reinforcing pipe having a predetermined length is driven at a predetermined elevation angle while sequentially adding the pipe materials to be formed.
[0004]
In this case, it is desirable to reduce the elevation angle as much as possible in order to prevent the top end from peeling off during tunnel excavation and to increase the restraint force of the ground in front of the face. By widening the tunnel cross section about 6m in front, the reinforcement pipe can be driven with a minimum elevation angle, and at the time of tunnel excavation, the support pipe laid on the inner peripheral surface is separated from the reinforcement pipe. Is to be minimized.
[0005]
FIG. 9 shows an example of a conventional injection-type long tip receiving method that is performed while widening the tunnel excavation section as described above. In the tunnel space 3, a long length from the face mirror 1 a to the ground 1 is shown. A reinforcing pipe 6 made of a steel pipe is provided. The reinforcement pipe 6 is a minimum from the inside of the wide steel support 4b in the face mirror part 1a provided with the mirror shot concrete 2 to the back of the steel support 4b 'in front of the face to be built later. It is placed in the front ground 1 with an elevation angle T of about 5 degrees away from the tunnel space 3 in order to exhibit the receiving effect at a distance.
[0006]
In order to maintain the above-mentioned elevation angle T, a section widening section S of about 6 m corresponding to the guide cell length of a rock drill such as a drill jumbo is provided, and steel already built in the immediate vicinity of the face mirror part 1a. A feature of the present construction method is that the reinforcement pipes are sequentially driven over the entire length in the circumferential direction of the tunnel at predetermined intervals with the lower end of the support 4b as a ruler.
[0007]
In addition, the solidified material is reinforced by injecting and solidifying the solidified material into the surrounding natural ground via the long reinforcing pipe placed as described above. Alternatively, a resin-based consolidated material is used. The consolidated material is injected from the mouth of the reinforcing pipe through a valve or divided injection with a partition wall, and a long reinforcing pipe as a receiving work and a consolidated area around the reinforcing pipe with the consolidated material (fixing) By forming the (region), the receiving restraint effect is exhibited.
[0008]
Recently, as described above, a non-widening type injection type long tip receiving method is used in which construction is performed without widening the tunnel excavation section. FIG. 10 shows an example of such a conventional non-widening type injection-type long tip receiving construction method. From the face mirror part 1a of the tunnel space 3 excavated without widening the tunnel cross section, into the front ground 1 When a reinforcing pipe 6 such as a steel pipe is driven at a predetermined elevation angle, and then the tunnel is excavated and the support work 4b is built, the reinforcing pipe 6 in the section L located at the face mirror part from the excavation cross section outer peripheral line. The rear end 6b is cut off.
[0009]
Therefore, at least the rear end 6b side of the reinforcing pipe 6 can be cut out from each other through joint means that can be easily separated from each other, for example, a plurality of short pipes matched to the tunneling length so that they can be cut out easily during tunnel excavation. Or a pipe made of a steel pipe or the like, or a pipe made of a slit in advance so as to be excised, or a synthetic resin pipe such as a vinyl chloride pipe.
[0010]
The rear end portion 6b of the reinforcing pipe 6 is buried in a natural ground so as to be located within a range of about 3 to 6 m of the support 4b to be built in front of the face. The part exposed from the mountain will be excised sequentially and the support will be built.
[0011]
In addition, in the reinforcing pipe 6 placed in the natural ground as described above and in the surrounding natural ground, the consolidated material G is injected to form a consolidated region 8 around the reinforcing pipe 6. The binder G is injected directly into the reinforcing tube 6 or is injected by inserting an injection tube such as an inner tube into the reinforcing tube. As the injection pipe, for example, a vinyl chloride pipe or an inner pipe made of synthetic resin is used. Then, by injecting cement-based or resin-based consolidated material G into the reinforcing pipe 6 through the injection pipe, it is inserted into the gap between the hole wall of the ground 1 where the reinforcing pipe 6 is placed. By filling the consolidation material G to fix the reinforcement pipe 6 and the natural hole wall, and by injecting the consolidation material G into the natural ground around the reinforcement pipe 6, the bonding force between rock fragments or soil particles In addition, the constraining effect of the ground in front of the face is enhanced by forming the consolidated region 8 around the reinforcing pipe 6.
[0012]
As an example of injecting the solidified material G in the above method, for example, there is a cement injection method shown in FIG. In this example, an injection pipe 10 such as a vinyl chloride pipe is accommodated in the reinforcing pipe 6, and exhausted into the injection pipe 10. Tube 11 The end opening of the reinforcing pipe 6 is stopped by a rubber stopper 15a and a stopper 15, and an injection hose 14a is connected to the injection pipe 10 via an injection valve 14. Further, a sealing material 25 such as a mouth caulk is applied between the specular sprayed concrete 2 and the outer peripheral surface of the rear end portion of the reinforcing tube 6, and cement-based consolidated material G is injected from the injection hose 14 a and the reinforcing tube 6 is inserted. The gap s between the drilled holes h is filled and fixed, and the consolidated material G is injected into the surrounding natural ground 1 to form the consolidated region 8.
[0013]
The above construction methods can be used for various ground conditions and can be used for long-span receiving, so the long-span receiving method is aimed at suppressing the preceding displacement of the ground, preventing loosening of the ground, and ensuring the safety of construction. It is used as.
[0014]
However, in addition to the fact that natural grounds that require the natural ground tip receiving method as described above are fragile, the natural ground near the face mirror part is loosened by excavation. For example, FIG. 12A shows the behavior around the face by numerical analysis. The behavior is in a relatively wide area R, and the behavior is larger in a darker area in the figure. D in the figure is the excision section. As shown in the figure, it can be confirmed analytically that fragile and extruding behavior exists as well as the face behavior during construction in a fragile ground condition.
[0015]
Therefore, in order to prevent the fall of the top edge and ensure the stability of the face, or to reduce the deformation of the natural ground, the leading work and the face mirror part reinforcement as shown in FIGS. 9 and 12 have been implemented. (b) Even if the construction work shown in (b) is carried out, there are still problems such as falling off of the natural ground from between the steel pipes, peeling of the natural ground below the steel pipes, deformation of the natural ground due to insufficient formation of the improved area, and increased surface subsidence. In many cases, even when the face mirror part reinforcement shown in FIG. 12 (c) is applied, troubles such as the collapse of the face, the occurrence of extrusion behavior, and the increase in the surface subsidence of the face of the face occur. In particular, in the long steel pipe tip receiver of the non-widening method shown in FIG. 12 (b), the reinforced pipe at the top face of the face and the ground in the thin layer section located on the tunnel excavation outer circumference are peeled off. Is likely to occur.
[0016]
Since the slime at the time of drilling is accumulated in the lower part of the already reinforced pipe, and the reinforcing pipe itself is in close contact with the lower part of the hole wall, the consolidation region by the injection material only for pressure injection is the reinforcing pipe. One reason for this is that an injection region is formed only in the upper portion of the pipe and the injecting material is difficult to rotate in the lower portion, so that an improved region composed of the already reinforced pipe and the improved ground is not secured. In addition, when the constant pressure is injected, clogging once generated in fine gaps and cracks is not eliminated, and it is easy to inject into concentrated gaps and cracks. It is also thought to be partly due to the heterogeneous improvements and vein-like improvements that were injected in an excellent way in a certain direction.
[0017]
In other words, in the conventional constant pressure injection, which is generally performed in the tunnel tip receiving method and face reinforcement, a non-homogeneous improvement body is formed mainly on the upper part of the steel pipe to obtain an appropriate ground reinforcement effect. As a result, ground deformation and ground subsidence cannot be effectively prevented, and there are many troubles such as fall of ground between steel pipes, collapse of a thin layer below the steel pipe, and collapse of the face.
[0018]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and in a ground reinforcement method such as a leading construction or a face mirror reinforcement, for example, along with an extrusion behavior that is a release stress at the time of tunnel excavation, a tunnel excavation cross section The ground in the area where the reinforcement pipe placed from the ground is cemented or resin-based solidified material, which suppresses the gradual increase of flaking and loosening that occurs due to insufficient fixation and improvement around the reinforcement pipe, and is highly uniform The ground reinforcement method that can demonstrate the injection reinforcement effect and does not require additional reinforcement at the time of tunnel excavation work, can obtain a suitable ground reinforcement effect, and can be constructed at low cost in various excavation methods. The purpose is to provide.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, the ground reinforcement method according to the present invention has the following configuration. That is, a reinforcing pipe having a predetermined length having a discharge hole on the peripheral surface is placed in the ground, and the solidifying material is injected into the reinforcing pipe to infiltrate the inside of the reinforcing pipe and the surrounding ground. In the natural ground reinforcement method to form a consolidated area in the natural ground, A rod-shaped body such as a steel bar is accommodated in the reinforcing pipe, When injecting the consolidated material into the reinforcing pipe, The vibration is applied to the vicinity of the end of the rod-shaped body, and the The caking material is injected into the reinforcing tube while transmitting vibrations to the caking material or the reinforcing tube or both.
[0020]
Further, the natural ground reinforcement method according to the present invention is a method in which a reinforcing pipe having a predetermined length having a discharge hole on its peripheral surface is placed in the natural ground, and a caking material is injected into the reinforcing pipe, and the ground in and around the reinforcing pipe. In the natural ground reinforcement method in which the solidified material is infiltrated into the mountain and a consolidated region is formed in the natural ground, an injection pipe or an inner pipe for injecting the solidified material into the reinforcing pipe is accommodated and disposed. When injecting the consolidated material into the tube, vibration is applied to the vicinity of the end of the injection tube or the inner tube, and the vibration is transmitted to the consolidated material or the reinforcing tube or both through the injection tube or the inner tube. A caking material is injected into the reinforcing pipe while .
[0021]
As the means for applying the vibration, a vibration generator such as a high-frequency vibration generator is used, and the vibration generator is the rod-shaped body. of Install it directly near the end or place it at any other position and lift it with appropriate vibration transmission means. Note You may make it transmit a vibration to the part vicinity.
[0022]
As described above, if there is an unfixed region of the solidified material and insufficient improvement at the lower end and the periphery of the reinforcing tube, the restraint force of the natural ground is impaired, and the gradual increase behavior of peeling or loosening is likely to occur, and the region where the reinforcing tube is located Even in situations where the hole wall is not self-supporting in a fragile ground, or where the hole wall collapses or the drilling slime is deposited around the reinforcing pipe and the lower end of the reinforcing pipe is in close contact with the hole wall, By transmitting vibration to the binder Reinforcement The degree of adhesion between the pipe and the hole wall decreases, and the slime also has fluidity by vibration, so that the function of the discharge hole that has been invalidated at the lower part of the reinforcing pipe is restored. In addition, the injection material is excited by applying vibration, fluidization is promoted, and the consolidated material is easily injected into the natural ground.
[0023]
In addition, vibration injection has a reverse movement compared to constant pressure injection, reducing the escape of the injected material in the direction that is easy to travel, suppressing clogging, and evenly over the entire circumference and length of the reinforcing pipe. It is injected and it becomes possible to satisfactorily form the fixing and improvement region by the caking material around the reinforcing tube.
[0024]
As a result, for example, in tunnel tip receiving work, a thin layer of natural ground that is easy to peel off from the reinforcement pipe to the outer periphery of the tunnel excavation cross section is secured a fixed area by the reinforcement pipe and the consolidated material, thereby increasing the binding force. As a result, the pushing behavior of the face mirror part during tunnel excavation is also suppressed, and stability is enhanced and rational reinforcement becomes possible. In addition, in the face mirror mirror reinforcement work, even when a reinforcing tube such as a synthetic resin tube that can be easily cut is used, the fixing region is surely formed around the entire length of the reinforcing tube by the caking material. Thus, it is possible to secure a required fixing force that can withstand the large pushing behavior of the face mirror part.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the ground reinforcement method according to the present invention will be described in detail based on the embodiment shown in the drawings. FIG. 1 is a longitudinal sectional view of a construction state in which the natural ground reinforcing method according to the present invention is applied to a receiving construction, FIG. 2 is a transverse sectional view thereof, and FIG. 3 is a partial enlarged longitudinal sectional view.
[0026]
In the tunnel under construction as shown in FIGS. 1 to 3, sprayed concrete 2 is applied to the face mirror part 1a of the natural ground 1, and a support is formed in the state where excavation has already been completed behind the face mirror part 1a. Yes. The tunnel space 3 is provided with shotcrete 4a so as to cover the ground of the side wall and the arch part, and a steel support 4b is formed inside the tunnel along the cross-sectional shape of the tunnel, and the tunnel excavation direction For example, it is built at predetermined intervals such as every 1 m.
[0027]
In the face mirror part 1a of the tunnel space 3, a receiving work 5 constructed prior to the excavation work is provided at predetermined intervals in the excavation direction as shown in FIG. 1, and in the circumferential direction of the tunnel as shown in FIG. It is arranged in the natural ground 1 so as to form an arch shape. The front receiving work 5 includes a reinforcing pipe 6 as a natural ground reinforcing material placed at a predetermined pitch along the cross-sectional shape of the tunnel and at a predetermined interval in the excavation direction, and a reinforcing pipe 6 via an injection pipe 10. And a bulkhead region formed on the face mirror part 1a side around the reinforcing tube prior to the formation of the consolidated region 8 7.
[0028]
The reinforcement pipe 6 is driven at a predetermined elevation angle from the outer periphery of the face mirror part 1a toward the front ground 1. In this embodiment, the tunnel excavation section is not widened as shown in FIGS. 1 and 3, and therefore, at the time of tunnel excavation, the rear end of the reinforcing pipe 6 corresponding to the length L in FIG. It is necessary to excise the part 6b, and the length L is set to about 4 m in this embodiment.
[0029]
Therefore, in the present embodiment, the front portion 6a of the reinforcing pipe 6 is composed of a plurality of relatively long steel pipes 61 (hereinafter referred to as long pipes) 61 connected to each other by male and female screw joints. The rear end 6b is a relatively short steel pipe (hereinafter referred to as a short pipe) 62 connected by a joint means 64 such as an easily breakable coupler, and a bulkhead region formation connected to the rearmost end of the short pipe 62. Lattice tube 63.
[0030]
The dimensions and the number of connections of the pipes 61 to 63 are appropriate. In the present embodiment, three steel pipes having an inner diameter (diameter) of 114.3 mm and a length of 3 m are connected as the long pipe 61, and the short pipe 62 is connected. Are three steel pipes having the same diameter and the same length as the long pipe 61, and the lattice pipe 63 is connected to the long pipe 61 and one lattice pipe having a steel wire mesh structure having the same diameter and a length of 1 m. Yes.
[0031]
In the reinforcing pipe 6, as shown in FIG. 4, an injection pipe 10 for injecting a caking material into the reinforcing pipe 6 and the surrounding natural ground, an inside of the reinforcing pipe when injecting the caking material, etc. An exhaust pipe 11 for discharging air remaining in the housing, a rod-like body 12 such as a steel bar, a packer 13 for forming a bulkhead, and the like are accommodated.
[0032]
In the present embodiment, an FRP (Fiberglass Reinforced Plastics) tube having an outer diameter (diameter) of 30.5 mm and a length of 6 m is used as the injection tube 10 in the present embodiment. The FRP injection tube has a strong feature against axial force, and can be easily excised with a drilling blade or the like during tunnel excavation.
[0033]
The rod-like body 12 imparts vibration and transmits the vibration to the consolidated material through the rod-like body. In this embodiment, a steel bar having a diameter of 16 mm is used. It is provided along with. The rod-shaped body 12 may be left in the reinforcing tube 6 even after the injection of the binder, which will be described later, or may be repeatedly used after being pulled out and removed from the reinforcing tube 6 after the injection of the binder. Further, the lengths of the rod-like body 12 and the exhaust pipe 11 are appropriate, but in this embodiment, they are formed to a length up to the vicinity of the tip of the reinforcing pipe 6.
[0034]
The injection pipe 10, the exhaust pipe 11, and the rod-shaped body 12 are appropriately formed of materials, diameters, and the like as long as they have a required strength. In such a case, it is desirable to use at least the rear end portion of a material or structure that can be easily excised with a drilling blade or the like during tunnel excavation, for example, a material that cannot be easily excised with a drilling blade during tunnel excavation, such as steel. In this case, a plurality of pieces that are cut into a predetermined unit length (for example, about 1 m) and connected by a plurality of joint means such as easily breakable couplers that can be easily broken by a drilling blade during tunnel excavation are used. You may do it.
[0035]
Further, in the present embodiment, the packer 13 is formed in a bag shape with a cloth or the like through which at least a part of the chemical solution for expansion can permeate, and in order to inject the chemical solution into the packer 13 An injection tube 13a such as a nylon tube is provided.
[0036]
The injection pipe 10, the exhaust pipe 11 and the rod-like body 12 are integrated as a bundler as shown in FIG. 4 (b) with a packer 13 wound around it and fastened with a fastener. The packer 13 is configured to be positioned in the lattice tube 63 by being inserted into the reinforcing tube 6 as shown in FIG. In the figure, 15 is a check valve stopper for suppressing the rubber plug 14 that closes the end of the

lattice tube

63, and 16 is an injection valve. One end of the valve 16 is connected to the injection tube 10 and the other end of the valve 16 is connected to the other end. The injection hose etc. which were abbreviate | omitted to are connected, and the solidification material is inject | poured in the reinforcement pipe | tube 6 through the said injection | pouring valve | bulb 16 and the injection | pouring pipe | tube 10 from the injection | pouring hose.
[0037]
In the above configuration, in order to construct the front receiving work 5 in the front ground 1 of the face mirror part 1a of the tunnel space 3, for example, the construction is performed according to the following procedure.
[0038]
FIG. 5 shows the construction procedure in the previous stage. First, as shown in FIG. 5 (a), the diameter from the predetermined position at the lower end of the supporting work 4b built just before the face mirror 1a toward the front ground 1 A long hole constituting a reinforcement pipe 6 in a guide cell 9a of a rock drill 9 such as a drill jumbo disposed in the tunnel space 3 as shown in FIG. The pipe 61 is placed, and the ring bit 21 is attached to the casing shoe 20 provided at the tip of the long pipe 61.
[0039]
Further, in the long pipe 61, a drilling rod 23 having an inner bit 22 attached to the tip is inserted, and the rear end of the drilling rod 23 is connected to a shank of a rock drill 9 such as a drill jumbo. Then, a striking force or a rotational force is transmitted to the ring bit 21 via the inner bit 22 at the tip of the drilling rod 23 to apply the drilling h, and at the same time, the long pipe 61 is inserted into the drilling h.
[0040]
In addition to the method of drilling with the inner bit 22 and the ring bit 21 as described above, for example, by mounting a diameter expanding bit at the tip of the drilling rod, Inserting the long pipe 61 into the long pipe 61 and transmitting the striking force or rotational force to the bit in a state where the diameter expanding bit is expanded at the tip of the long pipe 61, and simultaneously inserting the long pipe 61. May be.
[0041]
Further, at the time of drilling and insertion of the long tube 61, the guide cell 9a is set to a predetermined elevation angle T, for example, 3 to 6 degrees, preferably about 5 degrees, and from the lower hole h1 to the face mirror part 1a. The reinforcing pipe 6 is driven into the natural ground 1 located in the front while the hole h is formed with the bit.
[0042]
In the present embodiment, three long pipes 61 having a length of 3 m are sequentially screwed into the front portion 6 a of the reinforcing pipe 6, and then three pieces having a length of 1 m are provided on the rear end portion 6 b of the reinforcing pipe 6. A short pipe 62 and one lattice pipe 63 are driven. In this embodiment, the rear end of the long pipe 61, the short pipe 62, and the lattice pipe 63 are sequentially connected by the joint means 64 such as a breakable coupler as described above.
[0043]
A reinforcing tube 6 having a predetermined length made up of a plurality of long tubes 61, short tubes 62, and lattice tubes 63 is placed in the hole h, and the hole rod 23, the inner bit 22 and the like are Pull out and collect. Further, as shown in FIG. 5 (b), the reinforcing tube 6 and the lower hole h1 are filled with a sealing material 25 such as waste cloth and closed.
[0044]
In this state, for example, when a cement-based material is used as the consolidating material G for forming the consolidating region 8, the gel time is long, so in order to suppress leakage due to back pressure during injection, reinforcement is performed in advance. A bulkhead region 7 is formed on the rear end 6b side of the tube 6 as shown in FIG.
[0045]
As the chemical solution F forming the bulkhead region 7, for example, a urethane-based chemical solution is used, and when injected into the packer 13 from the injection tube 13 a, the packer 13 is filled with the chemical solution F, and the packer 13 is placed in the lattice tube 63. And the space in the lattice tube 63 is closed, and a part of the chemical solution injected into the packer 13 penetrates into the hole h and the surrounding natural ground, and the bulkhead region 7 Is formed. The bulkhead region 7 prevents the caking material from leaking to the face mirror portion 1a when a caking material for forming the caulking region 8 described later is injected into the reinforcing tube 6. It functions as a partition wall for preventing.
[0046]
When the bulkhead region 7 is formed as described above, an injection valve 16 is connected to the injection pipe 10 as shown in FIG. 5C, and the inside of the reinforcing pipe 6 is inserted through the injection valve 16 and the injection pipe 10. In this case, in the present invention, the above-mentioned consolidation material is injected while transmitting vibration to the above-mentioned consolidation material G or the reinforcing tube 6 or both. To do.
[0047]
In the present embodiment, a vibration generator 30 such as a high-frequency vibration generator is used as means for transmitting vibration to the consolidated material G or the reinforcing tube 6 or both, as shown in FIG. The installation position is appropriate, In case of figure Is attached to the vicinity of the rear end of the rod-like body 12 attached to the injection tube 10 and injected from the injection tube 10 into the reinforcing tube 6 through the rod-like body 12 and the injection tube 10. The vibration is transmitted to the consolidated material G or the reinforcing tube 6 or both.
[0048]
The vibration generating device 30 includes an adapter so that the device can be easily moved to a desired position, and thus can be easily moved to an arbitrary position. Further, the vibration generating device 30 includes the rod-shaped body 12 described above. of Place it at a position other than the vicinity of the rear end or at any other position, and place it through appropriate vibration transmission means. After You may make it transmit a vibration to edge part vicinity. Further, the means for applying vibration as described above is not limited to the above-described configuration, and can be appropriately changed as long as vibration can be transmitted to the consolidated material G and / or the reinforcing tube 6.
[0049]
By injecting the consolidated material G while transmitting vibration to the consolidated material G and / or the reinforcing tube 6 as described above, there is slime or hole wall collapse around the reinforcing tube 6, or Even in a state where the lower end is in close contact with the hole wall, the above-described vibration reduces the degree of adhesion between the reinforcing tube 6 and the hole wall, and the slime also has fluidity due to vibration, so that the discharge hole that has been in a closed state at the lower part of the reinforcing tube The functions of 61a and 62a are restored, and the consolidated material is excited and fluidity is excited from the discharge holes 61a and 62a formed on the peripheral surfaces of the long tube 61 and the short tube 62 constituting the reinforcing tube 6. In addition, it can be smoothly discharged into the surrounding natural ground 1 and can uniformly form the fixing and consolidation region 8 around the reinforcing tube 6 in front of the face mirror 1a as shown in FIG. 7 (a). It is.
[0050]
In particular, with the above-described configuration, the consolidated material also spreads to the lower region of the reinforcing pipe 6 that is difficult to move around simply by pressure injection, for example, and peeling between the outer peripheral line of the tunnel excavation section to be excavated later and the reinforcing pipe 6 It is possible to reinforce the easy thin layered ground. This also suppresses the push-out behavior of the mirror part during tunnel excavation, which increases the stability of the top edge of the face and enables rational reinforcement.
[0051]
The reinforcing tube 6 and the bulkhead region 7 and the consolidation region 8 are Or The above-mentioned front receiving work 5 is applied in an arch shape along the outer periphery of the face mirror part 1a in the tunnel as described above, and when the arch-shaped front receiving work 5 is constructed on the outer periphery of the face mirror part 1a, The stability of the natural ground 1 to be excavated located below is ensured. Then, as shown in FIG. 7B, the tunnel is further dug to advance the face mirror part 1a, and the support work 4b is built in order by the advance of the face face mirror part 1a to advance the tunnel excavation work.
[0052]
At that time, the natural ground 1 where the rear end portion 6b of the reinforcing pipe 6 of the receiving work 5 placed just before is also excavated, but when the excavation progresses, for example, by about 1 m, FIG. As shown in FIG. 3, in this example provided at the rear end portion 6b of the reinforcing tube 6, a 1-meter lattice tube 63 is cut away from the short tube 62, and at that time, the injection tube 10 and the rod-shaped body 12 are also cut off at the same time. The
[0053]
Thereafter, with the progress of tunnel excavation, the joint means 64 such as a breakable coupler is destroyed or the short pipe 62 is dropped from the joint means 64, and the short pipe 62 is sequentially cut out by 1 m and the injection pipe 10 is removed. The rod-shaped body 12 is excised along with the tunnel excavation. Finally, all the short pipes 62 located at the rear end 6b of the reinforcing pipe 6 are separated and removed, and the injection pipe 10 and the rod-like body 12 located at the rear end 6b of the reinforcing pipe 6 are cut off. is there.
[0054]
In the above embodiment, since the tunnel excavation cross-section is not widened along with the tunnel excavation, the support works 4b can be sequentially built in the same cross-section. Further, since the rear end portion 6b of the reinforcing pipe 6 is configured so as to be easily excised at the time of tunnel excavation as described above, the reinforcing pipe 6 alone can prevent a large push-out behavior of the face mirror part 1a generated at the time of tunnel excavation. However, there is a concern that sufficient strength cannot always be obtained, but it becomes possible to secure sufficient tensile rigidity originally necessary for the receiving work by the cooperation between the injection tube made of GFRP and the fixing region by the binder. . As a result, even in fragile ground conditions, the stability of the face mirror part is not impaired, the axial force as the receiving work is ensured properly, and the surrounding ground 1 is reinforced by the consolidated material G. In this way, the appropriate consolidation region 8 is formed, so that the stability of the natural ground is sufficiently ensured. Therefore, the tunnel excavation work can be performed efficiently and safely.
[0055]
In this embodiment, the reinforcing pipe 6 is composed of a relatively long steel pipe (long pipe) 61, a relatively short steel pipe (short pipe) 62, and a lattice pipe 63 having a steel wire mesh structure. The material, the connection structure, and the like can be changed as appropriate. For example, when the bulkhead region 7 does not need to be formed, a steel pipe or a resin pipe may be used instead of the lattice pipe 63, and the reinforcing pipe 6 The whole can also be composed of a single pipe.
[0056]
Moreover, in the said embodiment, although the cement-type solidification material whose hardening time is comparatively long was used as the solidification material G which forms the consolidation area | region 8, urethane-type solidification materials, such as urethane, a silica resin, and inorganic composite urethane, were used. Can also be used.
[0057]
Furthermore, although the said embodiment demonstrated as an example the case where a receiving work is constructed without widening a tunnel excavation cross section, it is applicable also when constructing by expanding a tunnel excavation cross section like the said FIG. .
[0058]
The present invention can also be applied to the face mirror part reinforcement work as shown in FIG. 12 (c), and FIG. 8 shows the construction state when applied to the face mirror part reinforcement work as described above. It is a longitudinal cross-sectional view of the principal part which shows an example.
[0059]
In the present embodiment, the reinforcing pipe 6 includes a plurality of FRP tubes 65 having an outer diameter of 76 mm, an inner diameter of 60 mm, and a length of 3 m, each of which has an outer peripheral surface subjected to groove processing that enhances adhesion to the consolidated material. The lattice tube 63 for forming the bulkhead region is connected to the tube 65 at the end of the tube 65 through a coupler 64, and the reinforcing tube 6 is disposed forward of the face mirror portion 1a. A mirror reinforcement work 5a under construction is provided in a ring shape toward the natural ground 1.
[0060]
The above The vibration generator 30 is ,Previous Fig. 6 It is attached to the rod-shaped body 12 (not shown) similarly to . Other configurations are the same as those of the above-described embodiment, and the same operational effects can be obtained.
[0061]
Furthermore, the present invention can be applied not only to the above-mentioned tunnel tip receiving work and face mirror part reinforcing work but also to various other natural ground reinforcing work methods, for example, when reinforcing the slope of a cliff, etc. The same effect as described above can be obtained.
[0062]
【Example】
As an example of the present invention, assuming the tunnel receiving work shown in FIGS. 1 to 3, using the above-described components, an actual on-site injection test (1) of dense sandy ground In the case of the case and in the case of the viscous ground as the injection test (2), the infiltration state of the solidified material into the ground (natural ground) was examined by conducting the solidified material injection test. Note that a cement-based caking material is used as the caking material, and a high-frequency vibration generating device is used as the vibration generator 30. 6's In this manner, the vibration was transmitted to the consolidated material sequentially injected into the reinforcing tube 6 through the rod-shaped body 12 at a frequency of 200 Hz.
[0063]
As a comparative example to the above example, an injection test was performed under the same conditions as in the above example except that the consolidated material was injected without applying vibration to the reinforcing tube 6 and the consolidated material by the vibration generator 30. It was. The results are summarized in Table 1 below.
[0064]
[Table 1]

[0065]
As described in Table 1 above, in each of the comparative examples, the amount of penetration of the consolidated material in the radial direction is small over the entire length in the circumferential direction of the reinforcing tube, and particularly in the lower portion of the reinforcing tube. Whereas the penetration of the material was slightly observable, in the examples according to the present invention, in any case, the fixing region of the consolidated material in the radial direction was secured over the entire circumferential length of the reinforcing tube, In particular, in the case of the dense sandy ground of the injection test (1), it has been found that a consolidated region (improved region) due to penetration of a consolidated material of 10 cm or more can be obtained also at the lower part and the side part of the reinforcing pipe. In addition, in the case of the viscous ground in the injection test (2), it is possible to prevent the consolidated material from running away in a certain direction, and to fix the radial direction over the entire length in the circumferential direction, thereby improving the ground more evenly. It could be confirmed.
[0066]
【The invention's effect】
As described above, the natural ground reinforcement method according to the present invention is such that when the consolidated material is injected into the reinforcing pipe placed in the natural ground and into the surrounding natural ground, the consolidated material or the reinforcing pipe or both are vibrated. Because of this, the fluidization of the consolidated material is promoted.For example, even in the situation where the slime deposited on the lower part of the reinforcing pipe and the reinforcing pipe are in close contact with the lower part of the hole wall, The solidified material can be satisfactorily penetrated into the natural ground, and the unfixed area can be reduced as much as possible. In particular, in tunnel tip receiving work and mirror part reinforcement work, the reinforcement pipes that fully exhibit the strength of cement-based or resin-based consolidated materials against the extrusion behavior that is the release stress during tunnel excavation. The surrounding natural ground restraint effect can be improved efficiently. In addition, the exfoliation caused by insufficient fixation around the reinforcement pipe and the extrusion behavior of the mirror part are suppressed, so that a highly uniform injection reinforcement effect can be demonstrated and there is no need for additional reinforcement during tunnel excavation work. Correspondence spreads and a suitable ground reinforcement effect can be obtained. Furthermore, the amount of work and cost for tunnel excavation can be greatly reduced, the construction period and construction cost for the auxiliary construction method can be suppressed, and the safety of work can be enhanced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a construction state showing an embodiment of a natural ground reinforcement method according to the present invention.
FIG. 2 is a cross-sectional view of the embodiment.
FIG. 3 is an enlarged longitudinal sectional view of a main part of the embodiment.
FIG. 4 is a configuration explanatory diagram of a reinforcing material used in the embodiment.
FIG. 5 is a process explanatory view showing a construction process in the former stage of the embodiment.
FIG. 6 is an explanatory diagram showing an arrangement configuration of a vibration generator.
FIG. 7 is a process explanatory view showing a construction process in the latter stage of the embodiment.
FIG. 8 is a longitudinal sectional view of a main part of an example in which the natural ground reinforcement method according to the present invention is applied to a mirror part reinforcement work.
FIG. 9 is a longitudinal sectional view showing an example of a conventional ground reinforcement method.
FIG. 10A is an explanatory view showing another example of a conventional ground reinforcement method.
(B) is the cross-sectional view.
FIG. 11 is a longitudinal sectional view showing an injection state of a consolidated material in a conventional ground reinforcement method.
FIG. 12A is an explanatory view showing a leakage state of a consolidated material in a conventional ground reinforcement method.
(B) The longitudinal cross-sectional view which shows an example of the conventional natural ground reinforcement construction method.
(C) The longitudinal cross-sectional view which shows the other example of the conventional natural ground reinforcement construction method.
[Explanation of symbols]
1 Ground
1a Face mirror part
2 Shotcrete
3 Tunnel space
4a shotcrete
4b Support work
5 Pre-construction work
6 Reinforcement pipe
61 Long pipe
62 Short tube
61a , 62a Discharge hole
63 Lattice tube
64 coupler
7 Bulkhead area
8 Consolidation area
9 Jackhammer
10 Injection tube
11 Exhaust pipe
12 Rod body
13 Packer
h Drilling
h1 pilot hole
G consolidated material

Claims

A reinforcing pipe having a predetermined length having a discharge hole in the peripheral surface is placed in the ground, and a solidifying material is injected into the reinforcing pipe so that the solidifying material penetrates into the reinforcing pipe and surrounding ground. In the natural ground reinforcement method for forming a consolidated area in the mountain, when a rod-shaped body such as a steel bar is accommodated in the reinforcing pipe and the consolidated material is injected into the reinforcing pipe, the vicinity of the end of the rod-shaped body A natural ground reinforcement method characterized by injecting a caking material into the reinforcing tube while applying vibration to the caking material and transmitting the vibration to the caking material or the reinforcing tube or both through the rod- like body .