JP4040151B2

JP4040151B2 - Reinforcing method for existing concrete structures

Info

Publication number: JP4040151B2
Application number: JP33090697A
Authority: JP
Inventors: 澄志前田; 繁和野瀬; 富士雄伊勢家; 晃弘森本; 嘉克木村
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 1997-11-14
Filing date: 1997-11-14
Publication date: 2008-01-30
Anticipated expiration: 2017-11-14
Also published as: JPH11148232A

Description

【０００１】
【産業上の利用分野】
本発明は、既設コンクリ−ト構造物の補強方法に関し、より詳細には柱、梁、壁面等の既設コンクリ−ト構造物、特に無筋コンクリ−ト構造物の亀裂、欠損等の損傷部分に熱硬化性樹脂組成物で含浸した高強度長繊維シ−トを接着した上からアンカ−ピン類を打ち込み、固定一体化し補強する方法に関するものである。
【０００２】
【従来の技術】
従来、既設のコンクリ−ト構造物等においては、構造部材の経年変化による劣化で設計時の性能を保持できなくなった構造物、或いはより優れた性能を必要とされ、特に既存構造物で古い設計基準で構築された無筋マンホ−ル（人孔）等では、亀裂や大気中の成分や湿潤状態によるコンクリ−トの劣化等により強度が低下するので、周囲に鉄板等の鋼材を巻き付け等により設け、該構造物と鋼材の間にモルタルや樹脂を注入して補強又は補修することが行われている。しかし、この方法では、鋼材の重量が構造物自体の重量を増加させることになり作業も大掛かりになる欠点がある。
【０００３】
そこで、経年劣化等による崩壊を防止するため、例えば特公平５−７３８６３号公報には、高強度繊維ストランドを構造物の柱に巻き付け、必要に応じて接着剤で該ストランドを柱に接着して補強することが開示されている。また、特開平４−８９９７０号公報にも、硬化剤を含む浸透させたテキスタイルを柱等の周囲に巻き付けて該硬化剤を硬化させることにより補強する方法が提案されている。さらに、構造物の周囲を鋼板や鉄筋篭で囲むことに代えて、たとえば特開平１−８３７６８号公報には、一体的な結合を避けるためにコンクリ−ト軸方向と周方向で異なる樹脂を用いて塗布し接着させる補強方法等の如く、近年、高強度繊維を捲回して補強する方法が提案されている。
【０００４】
【発明の解決しようとする課題】
しかしながら、上述のような従来の工法は、特に既存構造物で古い設計基準によって構築されたものでは、現行の基準や指針に比べて耐震補強性能等が劣り耐震補強を必要とするか、更に特に地中に埋設されている無筋マンホ−ルの天井、壁等の補修或いは補強では一般的に次に示すような問題点を抱えている。
（１）構造物としての機能性や、施工時の作業性の点で空間的な制約を受けること、また、使用材料が多く、またその自重が重く、作業能率や作業安全性の面で難点がある。特に、地下の無筋マンホ−ル等は、入口が狭く、鋼板等の資材の搬入が難しい。（２）従来の鉄筋コンクリ−ト増打工法も近年の炭素繊維シ−ト貼付工法でも、補強の必要区間に定着区間を加え貼付区間を広げることにより定着域を確保しているが、施工対象区間が冗長に成り勝ちであり、さらに柱〜梁の接合部分等の部材の変化箇所で使用する場合には有効な定着域を確保しにくい難点がある。この為、炭素繊維シ−ト貼付工法で定着区間を短縮する手段として、特開平４−１８９９７７号に既存コンクリ−ト躯体の補強構造、さらに特開平８−１２０９４８号公報には、このような場合での柱〜梁等の接合部分のような部材変化点の補強に適用する補強構造が提案されているが、この場合はテ−プ状の高強度繊維複合補強材を長手方向に貼着し、他方のコンクリ−ト躯体に穿設された挿入固定孔を設け、これに該補強材の端部を固着したフ−ブ巻で定着する接合部分を補強する稍複雑な構造でなければ定着区間を確保が難しい。（３）従来、一方向炭素繊維を用いた補強では、弾性率が２３．５トン／ｍｍクラスで、目付け２００ｇ／ｍ²程度の炭素繊維シ−トが使用されているが、この炭素繊維シ−トでは、１層当たりの剛性が低く、たとえば０．１５〜０．２０％程度迄の歪みの範囲を補強するには、補強箇所に炭素繊維シ−トを多層巻き付けるか、積層せざるを得ず、工期が長くかかったり、又は工事コストが嵩む難点があった。
また、（４）無筋コンクリ−トの耐久力実験の結果よれば、無筋コンクリ−トに炭素繊維シ−トを内側より貼付けたものを用い、上面より耐力テスト（載荷）を行ったところ、無筋コンクリ−トの上部位置と立上がり面の箇所より破壊されるとの知見を得た。このため本発明において、無筋コンクリ−トに高強度繊維シ−トを接着する複合材料の補強層では、常時かかる荷重の補強に関して既設コンクリ−ト構造物の歪みの範囲内で補強することが必要である。
【０００５】
本発明は、既設コンクリ−ト構造物の躯体外周面の亀裂、膨隆、座屈等の損傷部分に高強度長繊維シ−トを熱硬化性樹脂組成物で貼着し、或いは熱硬化性樹脂組成物を塗着又は含浸せしめた高強度長繊維シ−トを接着し、前記熱硬化性樹脂組成物を硬化せしめてなる既設コンクリ−ト構造物の補強方法であって、躯体外周面の亀裂、欠損等の損傷部分に樹脂注入手段の下地処理を施した後、前記コンクリ−ト構造物の損傷部分に躯体外周面の横幅方向及び長手方向に第１の高強度長繊維シ−トを少なくとも２層接着する工程と、さらに前記接着部位でかつ該損傷部分を覆う部位に第２の高強度長繊維シ−トを層着する工程と、前記既設コンクリ−ト構造物の躯体外周面に層状に形成した最外層の高強度長繊維シ−トの表面側より穿孔し係止固定具を所定の間隔で打ち込み既設コンクリ−ト構造物と前記高強度長繊維シ−トを固定することを特徴とする既設コンクリ−ト構造物の補強方法を提供することを目的とする。
【０００６】
【課題を解決するための手段】
前記目的を達成するため、本発明の既設コンクリ−ト構造物の補強方法では、躯体外周面の亀裂、欠損等の損傷部分に樹脂注入手段の下地処理を施した後、コンクリ−ト構造物の躯体外周面の亀裂、欠損やひび割れ部や膨隆等の損傷部分を高強度長繊維シ−トから選ばれた引張強度の大きい補強シ−トを少なくとも２層接着する第１の工程と、次に前記接着部位でかつ該損傷部分を覆う略有効な定着域に高強度長繊維シ−トを層着して補強する第２工程と、さらに前記既設コンクリ−ト構造物の躯体外周面に層状に形成した最外層の高強度長繊維シ−トの表面側より穿孔し、例えばアンカ−・ピン類の係止固定具を所定の間隔で打ち込んでなる既設コンクリ−ト構造物の補強方法であって、既設コンクリ−ト構造物と高強度長繊維シ−トを一体的に固定する既設コンクリ−ト構造物の補強方法により達成される。
【０００７】
【発明の実施の形態】
本発明の高強度長繊維シ−トに用いる高強度繊維としては、炭素繊維、芳香族ポリアミド繊維、ガラス繊維等より選ばれたものが適当である。これらの中でも炭素繊維は引張強度、引張弾性率が高く、軽量で高剛性である炭素繊維が本発明の解決手段として好適である。すなわち、高強度長繊維シ−トとして、たとえば炭素繊維シ−トは、弾性率３５トン／ｍｍ²以上の高弾性でありながら、破断伸度が０．９％以上の高弾性率、高伸度炭素繊維が適当であり、一般にコンクリ−トの引張破断伸度は約０．０３％といわれており、約０．１５％付近ではひび割れ、亀裂が発生し、このようなクラック等の発生する近傍は局部的な応力がかかる為、破断伸度が０．９％未満の中程度のものでは、該シ−トが破断してしまう場合がある。従って、少なくともくとも０．１５〜０．２％程度の歪み範囲での補強においても、破断伸度では０．９以上の高伸度品が適当である。
【０００８】
含浸用の樹脂としては、エポキシ樹脂が適当であり、繊維強化樹脂に使用できるものであれば特に限定されるものではないが、エポキシ樹脂接着剤に限らず、引張剪断強度が１０Ｋｇｆ／ｃｍ²程度以上の接着力を持つ接着剤であれば使用可能である。
【０００９】
本発明では、従来、一方向炭素繊維を用いた補強の場合、補強箇所に炭素繊維シ−トを多層巻き付け、或いは積層せざるを得ないのに対し、従来より少ない積層数で該シ−トの破断を起こさず、既設コンクリ−ト構造物の補強をすることができる為、工期が長引いたり、工事コストが嵩む欠点を解消することができる。
この為、本発明では、弾性率３５トン／ｍｍ²以上、破断伸度０．９以上の高弾性率、高伸度炭素繊維シ−トを使用し、繊維目付２５０ｇ／ｍ²以上で配列しものを使用することが好適である。
【００１０】
また、本発明で、高強度長繊維シ−トの多層巻き付け、或いは積層工程の簡略化、工事コストの低減を図るため、上記のごとき好適に用いられる高弾性率および高伸度の長繊維シ−トを使用すること、並びに既設コンクリ−ト構造物の損傷部分に躯体外周面の横幅方向及び長手方向に接着する第１の工程では、該長繊維シ−トは２層接着することにより補強する範囲に限った方法とし、さらに損傷部分を覆う第２層着工程との組み合わせとして、積層工程を簡略化、工事コストの低減を図った補強方法を提供する。
さらに、該高強度長繊維シ−トは、コンクリ−ト構造物の外周面に貼着又は巻き付け、接着剤により該構造物と一体化されるが、該シ−トの表裏間に積極的に接着剤を流通させる為の繊維空間を持たせた構成とし、繊維空間を介して表裏間に接着剤が流動し易いため、接着性が良好で強固に該シ−トとコンクリ−ト構造物とを一体化させることができる。このため該シ−トの積層或いは巻き付けが少なくなり、また、その幅方向の高強度長繊維が該長さ方向の該繊維を拘束するので、ほぼ均一な厚さの積層或いは巻き付けられ、局面や段差に対しての適合性が向上する。
【００１１】
また、本発明では、前記躯体外周面の円周方向に間隔をもって高強度長繊維シ−トを接着する工程と、該間隔に存在する亀裂等の内部へ樹脂を注入する手段を設けて樹脂を注入し、該注入手段を隔離させて少なくとも該間隔を覆うように高強度長繊維シ−トを接着せしめてなる既設コンクリ−ト構造物の補強ないし補修方法を提供する。
【００１２】
上記無筋コンクリ−トの耐久力実験の結果では、無筋コンクリ−トの上部位置と立上がり面の箇所より破壊されるとの知見に基づき、本発明では、既設コンクリ−ト構造物の躯体外周面に層状に形成した最外層の高強度長繊維シ−トの表面側より穿孔し係止固定具を所定の間隔で打ち込み既設コンクリ−ト構造物と前記高強度長繊維シ−トを固定することにより達成される。
【００１３】
上記の構成において、地下の無筋マンホ−ル等の入口が狭く搬入が難しい箇所でも補修或いは補強の為の施工が可能である。また、無筋マンホ−ルの内部よりの施工でコンクリ−ト構造物の補修或いは補強が可能で、耐震性及び設計荷重の大幅な向上ができ、大幅なコストの削減、工期の短縮が可能とするように働く。
さらに、特に地下マンホ−ル等での湿潤区間でも、熱硬化性樹脂の選択により強固に接着し、コンクリ−ト構造物の補修或いは補強が可能である。
また、本発明においては、柱、梁、壁面の剪断、曲げ補強、端部の定着、並びに補強繊維シ−ト貼付工法で定着区間を短縮する手段として、特に予め繊維をエポキシ樹脂のごとき熱硬化樹脂の一種以上より選ばれた樹脂組成物で含浸させながら一体化させ、好ましくは略３ｃｍ幅で、２層以上に積層した帯状シ−トの形態を採用することにより、補修作業を確実にすると共に、使い易さ、取扱い易さと併せ、補修、或いは補強による工程管理を容易とし、かつ帯筋の数倍の強度向上が期待でき、工期の短縮、コスト削減につながるように働く。
【００１４】
【実施例】
以下、本発明の一実施例を図面により説明する。
図１は既設コンクリ−ト構造物からなる無筋マンホ−ルに適用した実施例を示す要部説明図である。図１において、無筋マンホ−ルのコンクリ−ト躯体１は、マンホ−ル４、駆体頸部２、立上がり壁１６、及びボックスカルバ−ト３では床版天井６、上部ハンチ７、内壁８、下部ハンチ９、並びに土間１５の構成からなり、横幅方向は１．７１ｍ、長手方向の長さ３．８１ｍ、垂直高さ１．８１ｍのコンクリ−ト構造物を示している。
該マンホ−ル躯体１の構造物では、無筋コンクリ−ト製である故に、鉄筋の腐食或いは錆落としは要しないが、無筋の要因もあって該ボックスカルバ−ト３での床版天井６或いは内壁８、場合によっては上部ハンチ７及び下部ハンチ９の角縁箇所の躯体内周面には無数の亀裂、膨隆やひび割れ部や浮き上がりの損傷部分が発生して補強ないし補修を必要とする状態にある場合が多い状態である。
この実施例は、無筋コンクリ−ト製で、たとえば路面電車、自動車等の幹線道路で走行車両類の使用頻度が高く、万が一陥没すれば多大な影響が懸念される構造物に関し、このようなボックスカルバ−ト３での亀裂、膨隆やひび割れ部や浮き上がりの損傷部分の補強ないし補修のための構造並びに方法である。
【００１５】
このような亀裂、膨隆やひび割れ箇所の存在箇所を外部より全面にわたって調査し、少なくとも亀裂や欠損等のクラック幅が０．２ｍｍ以上のものをチェックした上、記録し、補強ないし補修のための施工法を検討の上、選定する。
【００１６】
施工第１工程、下地補修
まず、施工手順として、下地処理を施す工程、すなわち内部施工の第１工程として下地補修では、例えばひび割れ箇所では、汚れた部分を水洗いし、乾燥後、ＳＫグラウトプラグＡの台座を、ひび割れ箇所のクラックに沿って１ｍ当たり４〜５個、速硬性エポキシ樹脂で取り付け、該速硬性エポキシ樹脂でクラックを巾２０ｍｍ程度でシ−ルした。
次に、上記グラウトプラグＡにプラスチックの樹脂貯蔵タンクを取り付け、専用ガンにて、注入口よりエポキシ樹脂をタンクの目盛りの１．５を目途に注入を行い、タンク内のエポキシ樹脂が早く減る場合は追加注入を繰り返した。注入完了後、シ−ル材をサンディング除去した。
【００１７】
また、内部施工の第１工程として下地補修で、たとえば浮き、或いは欠損部では、ピンニング及び１０ｍｍ程度の凹み部は、水中硬化エポキシ樹脂パテで充填後、慣らしを行い、補強した。さらに、エポキシ樹脂の端部のバリは、スクレバ−、サンダ等でケレンした。
【００１８】
施工第２工程、高強度長繊維シ−ト貼付け
まず、施工第２工程での高強度長繊維シ−ト貼付けで、長手方向では、プライマ−をウ−ロ−ラ−で塗布後、エポキシ樹脂を高強度長繊維シ−ト巾で、長手方向にウ−ロ−ラ−で塗布し、該高強度繊維シ−トを貼付け、脱泡ロ−ラ−で内部の巻き込み空気を除去した。次いで、高強度長繊維シ−ト５を１ｃｍ程度ラップするようにエポキシ樹脂を塗布し、高強度長繊維シ−ト巾で、長手方向にウ−ロ−ラ−で塗布、順次貼付けていき、端縁部分の立ち上がり迄施工した。
また、短手方向では、高強度長繊維シ−ト５の２層目の貼付けは、プライマ−塗布後、エポキシ樹脂を用い、高強度長繊維シ−ト５を短手方向に貼付け、コ−ナ−部１１の部分迄施工した。
【００１９】
施工第３工程、補強
図１において、内壁８より床版天井６迄、該天井６より反対側の内壁８の上部ハンチ７および下部ハンチ９迄、エポキシ樹脂をウ−ロ−ラ−で塗布後、補強、帯筋用として高強度繊維シ−ト５を３０ｃｍ巾、１ｍ間隔で貼り付け後、長手方向に脱泡ロ−ラ−で、内部の巻き込み空気を除去して施工を行った。
【００２０】
上記の高強度長繊維シ−トを貼付ける施工第２工程、さらにエポキシ樹脂補強の施工第３工程によれば、コンクリ−ト製の駆体の下地補修を行った表面に、高強度長繊維シ−ト５がコンクリ−ト駆体の長手方向に沿って貼着され、次に、短手方向の２層目の貼付ける構成により、薄くて細長い高強度長繊維シ−ト５がコンクリ−ト駆体１に貼着される為、嵩高になる制約を受けず、軽量で取扱、ハンドリング性が良く、作業能率や安全性の向上を図れる。また、施工第２工程および施工第３工程完了後の構造物では、経時断面変化も僅少に抑制することができると共に、重量増加の影響を殆ど無視できる利点がある。
【００２１】
施工第４工程、高強度長繊維シ−トのアンカ−取付け
高強度長繊維シ−ト５とコンクリ−ト駆体１との接着破壊防止のため、補強、帯筋用として貼付けた部分を約５０ｃｍ間隔で穿孔し、ＳＫグラウトピン（５０ｍｍ）を挿入、専用の打ち込み棒を用いて、開脚用中ピンを打ち込み固定した。
次いで、専用ノズルをつけたグリスガンで注入材（水中硬化タイプ）エバ−ボンドＥＷ−１２８０（商標，世界長株式会社製）を充填し、特殊流出防止を打ち込み、注入材の流出防止と高強度長繊維シ−ト５と該駆体１との固定を行った。
【００２２】
上記施工第４工程での高強度長繊維シ−ト５のアンカ−取付けにより、既設コンクリ−トの損傷箇所での高強度長繊維シ−ト５の定着領域で、コンクリ−ト構造物に対し高強度長繊維シ−ト５を貼付け層着した２層の一体的、かつ強固な固着を図り得る。また、アンカ−取付けによって既設コンクリ−ト構造物に作用する引張力は、アンカ−・ピン類の如き係止具に対し軸に直交する方向であるが、穿孔に挿通し固定されるアンカ−・ピン類は、直交方向に対して高強度である。この為、既設コンクリ−ト構造物の外周面と高強度長繊維シ−ト５との接着或いは巻き付けと、アンカ−・ピン類の打ち込みを併用した固着層は界面に対する剪断力に対して大きな耐久性を発揮できる。
【００２３】
上記各工程において、使用材料は下記のとおりである。
１）低圧注入システム用には、ＳＫグラウトプラグ工法を採用し、世界長株式会社製のＳＫグラウトプラグを使用した。
２）台座取付け接着材（乾燥面）には、エバ−ボンドＧＰ−２（世界長株式会社製）を使用した。
３）注入材（水中硬化タイプ）は、エバ−ボンドＥＷ−１２８０（世界長株式会社製）を使用した。
４）埋め戻し材は、ＳＷモルタル（世界長株式会社製）を使用した。
５）高強度長繊維シ−ト固定用には、ＳＫグラウトピン（世界長株式会社製）を使用した。
６）駆体補強は、高強度長繊維シ−ト（弾性率３５トン／ｍｍ²以上、破断伸度０．９以上の高弾性率、高伸度炭素繊維シ−ト）を使用した。
【００２４】
図２は、図１の床版天井６の箇所での補強構造を示す断面要部説明図であり、コンクリ−ト製のボックスカルバ−ト３での亀裂、欠損、膨隆やひび割れ部や、浮き上がり等の損傷部１２を補強ないし補修する為のカ−ボン２層構造の断面
形態を示している。
【００２５】
図２で、損傷部１２の箇所に、第１カ−ボン層１０並びに第２カ−ボン層１１が層着されており、第２カ−ボン層１１の上面にカ−ボン補強の帯筋１３をあてがって当接状態としネイルアンカ−１４が打ち込まれており、該ネイルアンカ−１４の先端箇所は、一旦上記コンクリ−ト製のボックスカルバ−ト３に迄打ち込まれるときには、機構上先端部が先開き状態の構成となっている。これによって該ボックスカルバ−ト３に層着された第１カ−ボン層１０ならびに第２カ−ボン層１１および帯筋１３を横断的に強固、かつ永久的に固着セット可能な構成となっている。
【００２６】
図３は、図１のボックスカルバ−トでの内壁箇所Ｂの補強構造を示す断面要部説明図であり、コンクリ−ト製のボックスカルバ−ト３の内壁箇所Ｂでの亀裂、欠損部分に第１カ−ボン層１０を、次に第２カ−ボン層１１を層着した補強、補修状態を示している。
この場合、第１カ−ボン層１０を貼着する接着する接着剤としては、エポキシ樹脂或いは不飽和ポリエステル樹脂等を使用することができ、これらを予め下地処理を施した表面に塗布するか、第１カ−ボン層１０の高強度長繊維シ−ト５に塗布して使用する。次いで、上記施工第２工程での高強度長繊維シ−ト貼付け並びに施工第３工程での補強を同様に行い、第２カ−ボン層１１を層着した補強、補修状態の構成とすることができる。
【００２７】
また、本発明においては、上記第１カ−ボン層１０を層着し、次いで、第１カ−ボン層１０の高強度長繊維シ−ト５を貼着した接着剤がある程度固化した後、前記第１カ−ボン層１０の高強度長繊維シ−ト５の表面に第２カ−ボン層１１の高強度長繊維シ−ト５を層着させるが、樹脂は第１カ−ボン層１０の該長繊維シ−ト５の貼着用接着剤とを一体的に接合しないように接着強度を予め低く設定した構成とし、たとえば樹脂を溶媒で希釈する際にその濃度を低くするか、或いは樹脂自体の使用量を少量とし、必要に応じて比較的容易に接着強度を予め低く設定した構成とすることができる。
【００２８】
これによって、第１カ−ボン層１０は既設コクリ−トの損傷箇所の初期亀裂や欠損の発生を抑止すると共に、軸方向の曲げ応力に靱性を付与して既設コンクリ−トの構造物の強度を向上させることができる。また、該構造物に亀裂や欠損が発生し、その亀裂や欠損部分に応力が集中して第１カ−ボン層１０が破断のごとき状態に至ったとしても、この応力は第２カ−ボン層１１の高強度長繊維シ−ト５には分散して伝播され、第２カ−ボン層１１の高強度長繊維シ−ト５は引き続き既設コンクリ−ト構造物を強固に束縛する為、該構造物の靱性を維持し、亀裂や欠損箇所の損壊等の防止を図った構成とすることができる。
【００２９】
さらに、本発明の方法では、既設コンクリ−ト構造物に第１及び第２カ−ボン層の貼付工法で、曲げに対する応力材として高強度長繊維シ−ト５を、接着にはエポキシ樹脂剤を使用するが、該テ−プ状補強材は薄いため確実に貼付することができ、定着効果が大きく定着長を低減することができる。
また、応力材として高強度長繊維シ−ト５を使用し、該ボックスカルバ−ト３の内壁８のみならず端縁箇所の上部ハンチ７又は下部ハンチ９の施工も可能で、定着区間を確保できない箇所でも容易に適用でき、かつ第１及び第２カ−ボン層の工程集約により有効な補強ないし補修をなし得る利点がある。
【００３０】
以上に本発明に係る一実施例を詳述したが、具体的な構成はこの実施例に限られるものではなく、本発明の要旨を逸脱しない範囲の設計変更等があっても本発明に含まれる。
【００３１】
【発明の効果】
本発明は以上の通りであり、高強度繊維シ−トの使用により重量増加が少なく嵩高の制約を受けず、取扱性が良く、運搬持ち込みの他、作業能率、安全性等で大幅な改善を図り得る。また、補強施工後の構造物での断面変化が僅少で、死荷重の増加も認められない為構造系の変化を伴うことがない。
さらに、穿孔し係止固定具を所定の間隔で打ち込み該構造物と高強度繊維シ−トを一体的に強固に固定するため、有効かつ十分な補強効果を発揮する。また、端縁コ−ナ−部の施工も可能で、該構造物の剪断のみならず曲げも補強でき、第１及び第２カ−ボン層の工程集約が可能な構成とした為、工数の低減、コスト低下を図ることができる。
【図面の簡単な説明】
【図１】無筋マンホ−ルに適用した実施例を示す要部説明図である。
【図２】図１の床版天井のＡ箇所での補強構造を示す断面要部説明図である。
【図３】図１の内壁のＢ箇所での補強構造を示す断面要部説明図である。
【符号の説明】
１コンクリ−ト駆体
２躯体頸部
３ボックスカルバ−ト
４マンホ−ル
５高強度長繊維シ−ト
６床版天井
７上部ハンチ
８内壁
９下部ハンチ
１０第１カ−ボン層
１１第２カ−ボン層
１２損傷部
１３帯筋
１４ネイルアンカ−
１５土間
１６立上り壁[0001]
[Industrial application fields]
The present invention relates to a method for reinforcing an existing concrete structure, and more particularly to an existing concrete structure such as a column, a beam, or a wall surface, particularly a damaged portion such as a crack or a defect of an unreinforced concrete structure. The present invention relates to a method in which anchor pins are driven in after bonding a high-strength long fiber sheet impregnated with a thermosetting resin composition, and fixed and integrated for reinforcement.
[0002]
[Prior art]
Conventionally, in existing concrete structures, etc., structures that cannot maintain the performance at the time of design due to deterioration due to aging of structural members, or better performance is required, especially old designs with existing structures The strength of unmanned manholes (human holes) constructed based on the standards is reduced due to cracks, atmospheric components, concrete deterioration due to wet conditions, etc. It is provided and reinforced or repaired by injecting mortar or resin between the structure and the steel material. However, this method has a drawback in that the weight of the steel material increases the weight of the structure itself and the work becomes large.
[0003]
Therefore, in order to prevent collapse due to deterioration over time, for example, Japanese Patent Publication No. 5-73863 discloses that a high-strength fiber strand is wound around a pillar of a structure, and the strand is adhered to the pillar with an adhesive as necessary. Reinforcing is disclosed. Japanese Patent Application Laid-Open No. 4-89970 also proposes a method of reinforcing a hardened agent by winding a permeated textile containing a hardener around a pillar or the like. Further, instead of surrounding the structure with a steel plate or a steel bar, for example, Japanese Patent Laid-Open No. 1-83768 uses different resins in the concrete axial direction and the circumferential direction in order to avoid integral coupling. In recent years, a method of winding and reinforcing high-strength fibers has been proposed, such as a reinforcing method of applying and adhering.
[0004]
[Problem to be Solved by the Invention]
However, the conventional methods described above, especially those that are built on old structures and based on old design standards, are inferior in seismic reinforcement performance compared to current standards and guidelines, and more particularly require seismic reinforcement. In general, repair or reinforcement of the ceiling, walls, etc. of an unreinforced manhole embedded in the ground has the following problems.
(1) Being subject to spatial constraints in terms of functionality as a structure and workability during construction, and because it uses a lot of materials and its weight is heavy, it is difficult in terms of work efficiency and work safety. There is. In particular, underground unmanned manholes and the like have narrow entrances, making it difficult to carry in materials such as steel plates. (2) In both the conventional reinforcing steel concrete reinforcement method and the recent carbon fiber sheet affixing method, the fixing area is secured by adding the fixing area to the necessary area for reinforcement and expanding the affixing area. The section tends to be redundant, and there is a difficulty that it is difficult to secure an effective fixing area when used at a changed part of a member such as a column-beam joint. For this reason, as a means for shortening the fixing section by the carbon fiber sheet sticking method, Japanese Patent Laid-Open No. 4-189777 discloses a reinforcing structure of an existing concrete concrete case, and Japanese Patent Laid-Open No. 8-120948 discloses such a case. In this case, a tape-like high-strength fiber composite reinforcement is pasted in the longitudinal direction. The fixing section is provided if there is an insertion fixing hole formed in the other concrete housing, and the joining portion is fixed by a hood winding to which the end of the reinforcing material is fixed. It is difficult to secure. (3) Conventionally, carbon fiber sheets having a modulus of elasticity of 23.5 ton / mm class and a basis weight of about 200 g / m ² have been used for reinforcement using unidirectional carbon fibers. -In the sheet, the rigidity per layer is low. For example, in order to reinforce the strain range of about 0.15 to 0.20%, a carbon fiber sheet must be wound around the reinforcing portion in multiple layers or laminated. There was a problem that the construction period took a long time or the construction cost increased.
In addition, according to the results of (4) durability test of unmuscle concrete, a strength test (loading) was conducted from the top using a non-fiber concrete with a carbon fiber sheet affixed from the inside. In addition, the knowledge that it is destroyed from the upper position of the muscleless concrete and the location of the rising surface was obtained. For this reason, in the present invention, in the reinforcing layer of the composite material in which the high-strength fiber sheet is bonded to the unreinforced concrete, it is possible to reinforce within the range of distortion of the existing concrete structure with respect to the reinforcement of the load that is always applied. is necessary.
[0005]
In the present invention, a high-strength long fiber sheet is stuck with a thermosetting resin composition to a damaged portion such as a crack, a bulge, or a buckling of an outer peripheral surface of an existing concrete structure, or a thermosetting resin. A method for reinforcing an existing concrete structure in which a high-strength long-fiber sheet coated or impregnated with a composition is adhered and the thermosetting resin composition is cured, comprising cracks on the outer peripheral surface of the housing After applying the base treatment of the resin injection means to the damaged portion such as a defect, at least a first high-strength long fiber sheet is provided in the lateral width direction and the longitudinal direction of the outer peripheral surface of the casing on the damaged portion of the concrete structure. A step of adhering two layers, a step of laminating a second high-strength long fiber sheet at a portion covering the damaged portion at the bonding portion, and a layered structure on the outer peripheral surface of the frame of the existing concrete structure Perforated from the surface side of the outermost high strength long fiber sheet formed on Existing driving tool at predetermined intervals concrete - DOO structure and the high strength long fiber sheet - existing, characterized in that to fix the door concrete - and to provide a method for reinforcing bets structure.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the method for reinforcing an existing concrete structure according to the present invention, after the ground treatment of the resin injecting means is applied to a damaged portion such as a crack or a defect on the outer peripheral surface of the casing, A first step of adhering at least two layers of reinforcing sheets selected from high-strength long fiber sheets to the damaged parts such as cracks, defects, cracks and bulges on the outer peripheral surface of the casing; A second step of layering and reinforcing a high-strength long fiber sheet in a substantially effective fixing area that covers the damaged portion at the adhesion site, and further layered on the outer peripheral surface of the frame of the existing concrete structure A method of reinforcing an existing concrete structure in which holes are formed from the surface side of the formed high-strength long fiber sheet of the outermost layer, and anchoring fixtures such as anchor pins are driven at predetermined intervals. The existing concrete structure and high-strength long fiber sheet Existing concrete to secured - is achieved by the reinforcing method of preparative structure.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
As the high-strength fibers used in the high-strength long fiber sheet of the present invention, those selected from carbon fibers, aromatic polyamide fibers, glass fibers and the like are suitable. Among these, carbon fibers that have high tensile strength and tensile modulus, are light and have high rigidity, and are suitable as the solution of the present invention. That is, as a high-strength long fiber sheet, for example, a carbon fiber sheet has a high elastic modulus and high elongation with a breaking elongation of 0.9% or more while having a high elasticity with an elastic modulus of 35 ton / mm ² or more. Carbon fiber is suitable. Generally, the elongation at break of concrete is said to be about 0.03%, and cracks and cracks occur around 0.15%, and such cracks occur. Since a local stress is applied in the vicinity, the sheet may break when the elongation at break is medium than 0.9%. Accordingly, a high elongation product having a breaking elongation of 0.9 or more is suitable for reinforcement in a strain range of at least about 0.15 to 0.2%.
[0008]
As the resin for impregnation, an epoxy resin is appropriate and is not particularly limited as long as it can be used as a fiber reinforced resin. However, it is not limited to an epoxy resin adhesive, and a tensile shear strength is about 10 kgf / cm ^2. Any adhesive having the above adhesive strength can be used.
[0009]
In the present invention, conventionally, in the case of reinforcement using unidirectional carbon fibers, a carbon fiber sheet has to be wound or laminated around the reinforcement portion, whereas the sheet is laminated with a smaller number of layers than in the past. Since the existing concrete structure can be reinforced without causing breakage, it is possible to eliminate the disadvantage that the construction period is prolonged and the construction cost is increased.
For this reason, in the present invention, a high elastic modulus, high elongation carbon fiber sheet having an elastic modulus of 35 ton / mm ² or more and a breaking elongation of 0.9 or more is used and arranged with a fiber basis weight of 250 g / m ² or more. It is preferable to use one.
[0010]
Further, in the present invention, in order to simplify the multi-layer winding of the high-strength long fiber sheet or the laminating process and reduce the construction cost, the long fiber sheet having a high elastic modulus and high elongation that is preferably used as described above. -In the first step of using a sheet and adhering to the damaged part of the existing concrete structure in the lateral width direction and the longitudinal direction of the outer peripheral surface of the housing, the long fiber sheet is reinforced by adhering two layers. A reinforcing method that simplifies the lamination process and reduces the construction cost is provided as a method limited to the range to be applied, and in combination with a second layer attachment process that covers the damaged portion.
Further, the high-strength long fiber sheet is attached or wound around the outer peripheral surface of the concrete structure and integrated with the structure by an adhesive. A structure having a fiber space for distributing the adhesive, and the adhesive easily flows between the front and back sides through the fiber space, so that the adhesion between the sheet and the concrete structure is good and strong. Can be integrated. Therefore, the lamination or winding of the sheet is reduced, and the high-strength long fibers in the width direction restrain the fibers in the length direction, so that the layers can be laminated or wound with a substantially uniform thickness. The adaptability to the step is improved.
[0011]
Further, in the present invention, the step of adhering the high-strength long fiber sheet with an interval in the circumferential direction of the outer peripheral surface of the housing and a means for injecting the resin into the interior of the crack or the like existing in the interval are provided. There is provided a method of reinforcing or repairing an existing concrete structure in which a high-strength long fiber sheet is bonded so as to inject and isolate the injection means so as to cover at least the interval.
[0012]
As a result of the durability test of the above-mentioned muscleless concrete, based on the knowledge that it is broken from the upper position of the muscleless concrete and the position of the rising surface, in the present invention, the outer circumference of the existing concrete structure Perforated from the surface side of the outermost high-strength long fiber sheet formed into a layer on the surface, a locking fixture is driven at a predetermined interval to fix the existing concrete structure and the high-strength long fiber sheet. Is achieved.
[0013]
In the above configuration, construction for repair or reinforcement is possible even in places where the entrance of an underground unmanned manhole or the like is narrow and difficult to carry in. In addition, the concrete structure can be repaired or reinforced by construction from the inside of an unreinforced manhole, which can greatly improve earthquake resistance and design load, and can greatly reduce costs and construction time. To work.
Furthermore, even in a wet section such as in an underground manhole, the concrete structure can be firmly bonded by selecting a thermosetting resin, and the concrete structure can be repaired or reinforced.
Further, in the present invention, as a means for shortening the fixing section by column, beam, wall shearing, bending reinforcement, end fixing, and reinforcing fiber sheet affixing method, the fiber is preliminarily thermoset like epoxy resin. Reinforcing work is ensured by adopting a strip-like sheet form that is integrated while being impregnated with a resin composition selected from one or more kinds of resins, preferably approximately 3 cm wide and laminated in two or more layers. Along with ease of use and ease of handling, the process management by repair or reinforcement can be facilitated, and the strength can be improved several times that of the stirrups, leading to shortened construction period and cost reduction.
[0014]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view of a main part showing an embodiment applied to an unmuscle manhole made of an existing concrete structure. In FIG. 1, an unmuscle manhole concrete housing 1 includes a manhole 4, a body neck 2, a rising wall 16, and a box carb 3, a floor slab ceiling 6, an upper hunch 7, and an inner wall 8. The concrete structure is composed of a lower haunch 9 and a soil gap 15 and has a horizontal width direction of 1.71 m, a longitudinal length of 3.81 m, and a vertical height of 1.81 m.
Since the structure of the manhole housing 1 is made of unreinforced concrete, it does not require corrosion or rust removal of the reinforcing bars, but due to unreasonable factors, the floor slab ceiling in the box carbide 3 6 or the inner wall 8, and in some cases, innumerable cracks, bulges, cracks, and raised damaged parts are generated on the peripheral surface of the casing at the corners of the upper and lower hunches 7 and 9, requiring reinforcement or repair. This is a state that is often in a state.
This embodiment relates to a structure made of unreinforced concrete, for example, a structure in which traveling vehicles are frequently used on a main road such as a tram, an automobile, etc. This is a structure and method for reinforcing or repairing cracks, bulges, cracks, and raised damaged parts in the box carbonate 3.
[0015]
Examine the existence of such cracks, bulges and cracks from the outside, check at least cracks with crack widths of 0.2 mm or more, etc., record, record, and work for reinforcement or repair Select after considering the law.
[0016]
First step of construction, repair of the groundwork First, as a construction procedure, a process of groundwork treatment, that is, in the repair of the groundwork as the first step of internal construction, for example, in the cracked part, the dirty part is washed with water, dried, and then the SK grout plug A 4 to 5 per 1 m along the crack at the cracked portion were attached with a fast-curing epoxy resin, and the crack was sealed with the fast-curing epoxy resin to a width of about 20 mm.
Next, when a plastic resin storage tank is attached to the grout plug A, and the epoxy resin is injected from the injection port at the scale of 1.5 with the dedicated gun, and the epoxy resin in the tank decreases quickly. Repeated additional injections. After the injection was completed, the seal material was removed by sanding.
[0017]
Also, as a first step of internal construction, repairing the foundation, for example, in the floating or missing part, the pinning and the recessed part of about 10 mm were filled with an underwater-cured epoxy resin putty and then conditioned and reinforced. Further, burrs at the end of the epoxy resin were cleaned with a scrubber, a sander or the like.
[0018]
Construction second step, high strength long fiber sheet pasting First, in the construction second step, high strength long fiber sheet pasting, in the longitudinal direction, the primer is applied with a roller and then epoxy resin Was applied with a roller in the longitudinal direction with a high-strength long fiber sheet width, the high-strength fiber sheet was affixed, and the internal air was removed with a defoaming roller. Next, an epoxy resin is applied so as to wrap the high-strength long fiber sheet 5 by about 1 cm, with a high-strength long fiber sheet width, applied in a longitudinal direction with a roller, and sequentially pasted, The construction was continued until the end of the edge.
In the short direction, the second layer of the high-strength long fiber sheet 5 is affixed with the epoxy resin after applying the primer, and the high-strength long fiber sheet 5 is pasted in the short direction. Construction was done up to the part of the knurled part 11.
[0019]
3rd step of construction, reinforcement In FIG. 1, after applying epoxy resin with a roller, from the inner wall 8 to the floor slab ceiling 6, to the upper haunch 7 and the lower haunch 9 of the inner wall 8 opposite to the ceiling 6 After the high-strength fiber sheet 5 was pasted at 30 cm width and 1 m intervals for reinforcement and band reinforcement, the work was carried out by removing the entrained air inside with a defoaming roller in the longitudinal direction.
[0020]
According to the second construction step for pasting the above-mentioned high-strength long fiber sheet, and further the third construction step for epoxy resin reinforcement, the high-strength long fiber is applied to the surface of the concrete made body repair. The sheet 5 is adhered along the longitudinal direction of the concrete body, and then the thin and long high-strength long fiber sheet 5 is concreted by the structure of the second layer in the short direction. Since it is affixed to the body 1, it is not subject to bulky restrictions, is light in weight, has good handling and handling properties, and can improve work efficiency and safety. Further, the structure after completion of the second construction step and the third construction step has the advantage that the cross-sectional change with time can be slightly suppressed and the influence of the weight increase can be almost ignored.
[0021]
4th step of construction, anchor attachment of high-strength long-fiber sheet In order to prevent adhesion failure between the high-strength long-fiber sheet 5 and the concrete body 1, the part pasted for reinforcement and band is about The holes were drilled at intervals of 50 cm, SK grout pins (50 mm) were inserted, and the middle pins for opening legs were driven and fixed using a dedicated driving rod.
Next, infused material (underwater curing type) Eva Bond EW-1280 (trademark, manufactured by World Director Co., Ltd.) is filled with a grease gun equipped with a special nozzle, and special outflow prevention is driven in to prevent outflow of the injected material and high strength length The fiber sheet 5 and the precursor 1 were fixed.
[0022]
With the anchor attachment of the high-strength long fiber sheet 5 in the fourth construction step, with respect to the concrete structure in the fixing region of the high-strength long fiber sheet 5 at the damaged portion of the existing concrete It is possible to achieve an integral and strong fixation of the two layers in which the high-strength long fiber sheet 5 is adhered and adhered. In addition, the tensile force acting on the existing concrete structure by anchor attachment is in a direction perpendicular to the axis with respect to a locking tool such as an anchor pin, but the anchor inserted through the hole is fixed. The pins are high in strength in the orthogonal direction. For this reason, the fixed layer that combines the adhesion or winding of the outer peripheral surface of the existing concrete structure and the high-strength long fiber sheet 5 and the driving of anchors and pins is highly durable against the shearing force on the interface. The ability to demonstrate.
[0023]
In each of the above steps, the materials used are as follows.
1) For the low-pressure injection system, the SK grout plug method was adopted, and the SK grout plug manufactured by World Chief Corporation was used.
2) Eva-bond GP-2 (manufactured by World Head Co., Ltd.) was used for the base mounting adhesive (dry surface).
3) Eva-Bond EW-1280 (manufactured by World Head Co., Ltd.) was used as the injection material (in-water curing type).
4) As the backfilling material, SW mortar (manufactured by World Director) was used.
5) An SK grout pin (manufactured by World Head Co., Ltd.) was used for fixing the high-strength long fiber sheet.
6) For the reinforcement of the fuselage, a high-strength long fiber sheet (elastic modulus of 35 ton / mm ² or more, high elasticity of breaking elongation of 0.9 or more, high elongation carbon fiber sheet) was used.
[0024]
FIG. 2 is a cross-sectional explanatory diagram showing a reinforcing structure at the floor slab ceiling 6 in FIG. 1 and shows cracks, defects, bulges and cracks in the box box 3 made of concrete, and floating. 2 shows a cross-sectional form of a carbon two-layer structure for reinforcing or repairing a damaged portion 12 such as the above.
[0025]
In FIG. 2, a first carbon layer 10 and a second carbon layer 11 are deposited at the damaged portion 12, and a carbon reinforcing band is formed on the upper surface of the second carbon layer 11. The nail anchor 14 is driven into a contact state by applying the No. 13, and the tip portion of the nail anchor 14 is once driven into the box box 3 made of the above-mentioned concrete. Is configured to be opened first. As a result, the first carbon layer 10, the second carbon layer 11, and the band 13 layered on the box carbonate 3 can be firmly and permanently fixed and set. Yes.
[0026]
FIG. 3 is a cross-sectional explanatory view showing the reinforcing structure of the inner wall portion B in the box carbato of FIG. 1, and in the cracks and missing portions in the inner wall portion B of the box box carat 3 made of concrete. The reinforcing and repairing states in which the first carbon layer 10 and then the second carbon layer 11 are applied are shown.
In this case, as an adhesive for adhering the first carbon layer 10, an epoxy resin or an unsaturated polyester resin can be used, and these are applied to a surface that has been subjected to a base treatment in advance. The first carbon layer 10 is used after being applied to the high-strength long fiber sheet 5. Next, the high-strength long fiber sheet pasting in the second construction step and the reinforcement in the third construction step are performed in the same manner, so that the second carbon layer 11 is layered and repaired. Can do.
[0027]
In the present invention, after the first carbon layer 10 is deposited, and then the adhesive to which the high-strength long fiber sheet 5 of the first carbon layer 10 is adhered is solidified to some extent, The high strength long fiber sheet 5 of the second carbon layer 11 is deposited on the surface of the high strength long fiber sheet 5 of the first carbon layer 10, but the resin is the first carbon layer. The adhesive strength is set to be low in advance so as not to integrally bond the ten long fiber sheet 5 adhesives, for example, when the resin is diluted with a solvent, the concentration is lowered, or A small amount of the resin itself can be used, and the adhesive strength can be set low in advance relatively easily if necessary.
[0028]
As a result, the first carbon layer 10 suppresses the occurrence of initial cracks and defects at the damaged portion of the existing concrete and imparts toughness to the bending stress in the axial direction, thereby strengthening the structure of the existing concrete. Can be improved. Further, even if cracks or defects occur in the structure and stress concentrates on the cracks or defects, and the first carbon layer 10 is in a state of fracture, the stress is applied to the second carbon. The high-strength long fiber sheet 5 of the layer 11 is dispersed and propagated, and the high-strength long fiber sheet 5 of the second carbon layer 11 continues to firmly bind the existing concrete structure. It can be set as the structure which maintained the toughness of this structure and aimed at prevention of the crack of a crack, a defect | deletion location, etc.
[0029]
Furthermore, in the method of the present invention, the first and second carbon layers are applied to the existing concrete structure, and the high-strength long fiber sheet 5 is used as a stress material for bending, and the epoxy resin agent is used for adhesion. However, since the tape-shaped reinforcing material is thin, it can be reliably affixed, the fixing effect is great, and the fixing length can be reduced.
In addition, using high-strength long fiber sheet 5 as a stress material, it is possible to construct not only the inner wall 8 of the box carbonate 3 but also the upper haunch 7 or the lower haunch 9 at the edge portion, ensuring a fixing section. There is an advantage that it can be easily applied even where it cannot be performed, and that effective reinforcement or repair can be performed by integrating the processes of the first and second carbon layers.
[0030]
Although one embodiment according to the present invention has been described in detail above, the specific configuration is not limited to this embodiment, and design changes and the like within a scope not departing from the gist of the present invention are included in the present invention. It is.
[0031]
【The invention's effect】
The present invention is as described above. By using a high-strength fiber sheet, there is little increase in weight and there is no restriction on bulkiness, good handling, and in addition to carrying around, work efficiency, safety, etc. are greatly improved. It can be planned. In addition, there is little change in the cross section of the structure after reinforcement work, and no increase in dead load is observed, so there is no change in the structural system.
Further, the structure is punctured and the locking fixture is driven at a predetermined interval to firmly and firmly fix the structure and the high-strength fiber sheet, so that an effective and sufficient reinforcing effect is exhibited. In addition, it is possible to construct the edge corner, and not only can the structure be sheared but also bend, and the process can be integrated into the first and second carbon layers. Reduction and cost reduction can be achieved.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a main part explanatory view showing an embodiment applied to an unmuscle manhole.
FIG. 2 is a cross-sectional explanatory view of a principal part showing a reinforcing structure at a location A of the floor slab ceiling of FIG. 1;
FIG. 3 is a cross-sectional view illustrating a main part of a reinforcing structure at a location B of the inner wall in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Concrete drive body 2 Body neck 3 Box carbonate 4 Manhole 5 High-strength long fiber sheet 6 Floor slab 7 Upper haunch 8 Inner wall 9 Lower haunch 10 1st carbon layer 11 2nd car -Bon layer 12 Damaged part 13 Band 14 Nail anchor-
15 Doma 16 Rise Wall

Claims

A high-strength long fiber sheet is attached with a thermosetting resin composition to a damaged portion such as a crack, a bulge, or a buckling of the outer peripheral surface of an existing concrete structure, or a thermosetting resin composition is applied. A method for reinforcing an existing concrete structure, wherein a high-strength long fiber sheet that has been attached or impregnated is adhered, and the thermosetting resin composition is cured.
Crack skeleton outer peripheral surface, and facilities to process the surface treatment of the resin injected into the damaged portion of the defect or the like,
Adhering at least two layers of the first high-strength long fiber sheet to the damaged portion of the concrete structure in the lateral width direction and longitudinal direction of the outer peripheral surface of the housing ;
Layering a second high-strength long fiber sheet on the adhesion site and the site covering the damaged portion;
The existing concrete structure and the above-mentioned concrete structure and the above-mentioned are punched from the surface side of the outermost high-strength long fiber sheet formed in a layered manner on the outer peripheral surface of the existing concrete structure, and driven in at a predetermined interval. Process for fixing high-strength long fiber sheet
A method for reinforcing an existing concrete structure, comprising:

A step of adhering the high-strength long fiber sheet at intervals in the circumferential direction of the outer peripheral surface of the housing, and a means for injecting resin into cracks, defects, etc. existing at the intervals, and injecting the resin; 2. A method for reinforcing an existing concrete structure according to claim 1, wherein the high strength long fiber sheet is adhered so as to isolate the injection means and cover at least the interval.

3. An existing concrete structure according to claim 1 or 2, wherein said locking fixture is composed of anchor pins, and 2 to 6 pieces are driven per square meter to fix a high strength long fiber sheet. How to reinforce things.