JP3689840B2 - Seismic reinforcement method for existing structure foundation - Google Patents

Seismic reinforcement method for existing structure foundation Download PDF

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JP3689840B2
JP3689840B2 JP07944899A JP7944899A JP3689840B2 JP 3689840 B2 JP3689840 B2 JP 3689840B2 JP 07944899 A JP07944899 A JP 07944899A JP 7944899 A JP7944899 A JP 7944899A JP 3689840 B2 JP3689840 B2 JP 3689840B2
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Japan
Prior art keywords
footing
micropile
seismic reinforcement
improved
pile
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JP07944899A
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JP2000273881A (en
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憲二郎 岡
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Toray Engineering Co Ltd
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Toyo Construction Co Ltd
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Description

【0001】
【発明が属する技術分野】
本発明は、橋脚、ビル等の既設構造物の基礎の耐震性を高めるための耐震補強工法に関する。
【0002】
【従来の技術】
既設構造物の基礎の耐震補強を行う場合、基礎の耐力(支持力)の増大と地盤の液状化の防止とが重要な課題となり、従来よりこの二つの課題を解決するための種々の工法が開発されている。すなわち、耐力を増大させる工法としては、例えば、杭基礎の周囲に増し杭を打設して、この増し杭と既設フーチングとを一体化する増し杭工法、増し杭の代わりに地中連続壁や鋼管矢板基礎を増設して、これらと既設フーチングとを一体化する工法等がある。また、液状化を防止する工法としては、例えば、基礎地盤の周りをコンクリート壁、矢板壁等で囲んで地震時に発生する地盤のせん断変形を抑制する工法、フーチング下面から支持層まで高圧噴射攪拌工法等の固化工法を施工して基礎地盤を改良する固化工法等がある。
【0003】
【発明が解決しようとする課題】
しかしながら、上記した各工法は、何れも施工が大がかりとなっており、広い工事スペースが必要となるばかりか、工期の延長や工費の上昇が避けられないという問題があった。
また、上記した各工法は、基礎の耐力の増大と地盤の液状化防止との何れか一方に対してのみ有効となっており、耐震補強の面で、いま一つ信頼性に欠けるという問題があった。
なお、最近では、上記した増し杭工法の増し杭として、施工簡単なマイクロパイルを用いる工法も開発されているが(例えば、特開平10−140583号公報参照)、マイクロパイルを用いても液状化を防止できないことは、従来の増し杭工法と何ら変わるところはない。
【0004】
本発明は、上記従来の問題点を解決するためになされたもので、その目的とするところは、基礎の耐力増大と地盤の液状化防止とを同時に達成することができる、施工簡単な既設構造物基礎の耐震補強工法を提供することにある。
【0005】
【課題を解決するための手段】
上記目的を達成するため、本発明は、既設構造物のフーチング下の基礎の周りの地盤中に、高圧噴射攪拌工法により改良柱を造成すると共に、該改良柱内に鋼管を芯材とするマイクロパイルを打設し、前記した改良柱の造成とマイクロパイルの打設とを前記改良柱が相互にラップするように連続に行って、前記基礎を囲む連続壁を構築し、しかる後、前記マイクロパイルの杭頭部を包むように前記フーチングを増設することを特徴とする。
【0006】
このように行う既設構造物基礎の耐震補強工法においては、高圧噴射攪拌工法を利用することで大径の改良柱を造成することができ、この改良柱の造成を相互にラップさせて連続に行うことでフーチング下の基礎を囲む連続壁を簡単に構築することができる。そして、この連続壁の存在により地震時にフーチング下の地盤のせん断変形が抑制され、地盤の液状化が防止される。
また、この連続壁を構成する各改良柱内に鋼管を芯材とするマイクロパイルを打設し、しかも、各マイクロパイルの杭頭部をフーチングの増設部分に包んでフーチングと一体化しているので、基礎そのものの支持力も十分となる。
【0007】
本発明は、上記改良柱を、フーチングの外周縁部を抱込む形態で造成するのが望ましく、これにより、フーチングと改良柱とが密着して、フーチングから改良柱への荷重伝達が確実となる。
本発明はまた、各マイクロパイルの杭頭部を相互に連結した後、フーチングを増設するの望ましく、これにより、マイクロパイルの杭頭部とフーチングとの一体化がより確実となって、基礎の耐力がより一層向上するようになる。
本発明さらに、マイクロパイルの鋼管内に、H形鋼、鋼管、棒鋼等の補強用部材を挿入するようにしてよく、これにより、マイクロパイル自体の水平抵抗力(曲げ剛性)が増大し、大型の既設構造物の耐震補強としての信頼性が著しく向上する。
【0008】
【発明の実施の形態】
以下、本発明の実施例を添付図面に基いて説明する。
【0009】
図1および2は、本発明に係る耐震補強工法の一つの実施の形態を示したものである。本実施の形態は、既設構造物としての橋脚1の基礎を対象になされたもので、橋脚1は、その底部に一体に設けたフーチング2を地盤3中に打設した複数の杭4上に載せた状態で据付け固定されている。各杭4は、それぞれの先端が支持地盤5に到達するまで地盤3内に打込まれており、その複数がまとまって一つの杭基礎6を構成し、所定の耐力(支持力)を発揮するようになっている。しかして、この杭基礎6の周りには本工法による円環状連続壁10が構築され、一方、地盤3の地表面側には、前記連続壁10の上端部と橋脚1のフーチング(既設フーチング)2とを連接一体化する増設フーチング11が構築されている。
【0010】
上記連続壁10は、後述する高圧噴射攪拌工法により地盤3中に造成された大径の改良柱12と、この改良柱12の軸心位置に後述の方法で打設されたマイクロパイル13とからなる複合体14を一単位として、この複合体14の複数を相互にラップさせながら連接した構造となっている。この複合体14を構成する改良柱12は、既設フーチング2の外周縁部を抱込む形態で造成されており、したがって、既設フーチング2は、その外周縁部の下面が各複合体14の改良柱12に支承された状態となっている。また、マイクロパイル13は、中空の芯材(鋼管)15とその周りの定着層16とからなっており、その芯材15は定着層16を介して改良柱12に強固に定着されている。一方、各マイクロパイル13の杭頭部13aは、相互に鉄筋、フレーム等の連結部材(図示略)により連結された状態で、前記増設フーチング11内に埋込まれており、これにより、連続壁10と既設フーチング2とは増設フーチング11を介して強固に一体化されている。
【0011】
本工法の実施に際しては、予め削孔機を利用して杭基礎6の周りの地盤3中に支持地盤5に到達するガイド穴20(図3)を削孔する。そして、図3に示すように、先ず、管壁に複数の逆止弁21を有する鋼管22内に、先端に噴射ノズル23を有する注入ロッド24を挿入し、両者を図示を略す処理機に支持させて前記ガイド穴20に一体的に挿入する。この時、図3の▲1▼に示すように、鋼管22の先端から注入ロッド24の先端の噴射ノズル23が突出するように両者を位置決めし、かつ注入ロッド24を回転させる。そして、噴射ノズル23が前記既設フーチング2の側方位置S1 まで到達したら、回転する注入ロッド24内にセメントミルクなどのグラウト(水−セメント比(W/C) 60〜70%程度)を圧送する。すると、注入ロッド24の先端の噴射ノズル23から周辺地盤にグラウトが高圧噴射され、このグラウトによって鋼管22の周りの地盤が攪拌混合され、大径の攪拌混合層25が形成される。
【0012】
上記攪拌混合層25は、鋼管22および注入ロッド24の下降に応じて次第に下方へ拡大し、噴射ノズル23がガイド穴20の底部に到達した段階では、図3の▲2▼に示すように、地盤3と支持地盤5との境界S2 を越えて支持地盤5内にわずか食込むまで拡大する。そして、この段階で流入ロッド24に対するグラウトの圧送を停止し、注入ロッド24を鋼管22から引抜いて、その代わりに、図3の▲3▼に示すように注入機(ダブルパッカー)26を鋼管22内に挿入する。注入機26は、膨出変形可能な一対の膨出体27を備えており、最初、この注入機26を鋼管22の最深位置に挿入し、この最深位置で一対の膨出体27を膨張させて注入機25を位置固定し、これに供給管28を通じてセメントモルタルなどの硬化材グラウト(水−セメント比(W/C) 40〜50%程度)を圧送する。すると、この硬化材グラウトは、前記鋼管22の管壁の逆止弁21を開いて鋼管22の周りに噴出し、前記攪拌混合層25に混入して、鋼管22の周りには硬化材注入層29が形成される。この硬化材注入層29は、注入機26を所定のピッチで引上げながら前記操作を繰り返すことで上方へ拡大し、前記既設フーチング2の側方位置S1 まで注入機26を引上げた段階で硬化材グラウトの噴出を停止し、そのまま注入機26を鋼管22から引抜く。
【0013】
上記攪拌混合層25および硬化材注入層29は、所定時間経過すると硬化して、それぞれ改良柱12およびマイクロパイル13の定着層16に変質し、杭基礎6の周りには、図1に示すように、改良柱12とマイクロパイル13とが一体となった一つの複合体14が形成される。この場合、上記逆止弁21付きの鋼管22は、そのままマイクロパイル13の芯材15として残る。本実施の形態では、この複合体14の形成を前記改良柱12が相互にラップするように連続に行って、杭基礎6を囲む連続壁10を構築する。
【0014】
上記連続壁10の造成が完了したら、先ず、この上の地表面を掘削してマイクロパイル13の杭頭部13aと既設フーチング2とを露出させる。次に、各マイクロパイル13の杭頭部13aを相互に連結部材を用いて連結し、これと並行して、既設フーチング2の表面をはつり、場合によっては鉄筋を露出させる。鉄筋を露出させた場合は、その鉄筋および前記杭頭部13aを連結する連結部材に接続させた状態で、既設フーチング2の周りに新規の鉄筋を組込み、前記杭頭部13aを含む既設フーチング2の周りにコンクリートを打設する。これにより、増設フーチング11が構築され、杭基礎6を囲む連続壁10がこの増設フーチング11を介して既設フーチング2に強固に一体化され、この結果、既設構造物としての橋脚1の基礎の耐力(支持力)が大きく増大し、地震時の揺れにも耐えるようになる。本実施の形態においては特に、改良柱12の造成用グラウトとしてW/C比60〜70%程度のものを、マイクロパイル13の造成用グラウトとしてW/C比40〜50%程度のものをそれぞれ用いているので、改良柱12自体の強度が十分大きくなることに加え、この改良柱12とマイクロパイル13との接合強度も十分大きくなり、橋脚1の基礎の支持力は著しく増大する。
【0015】
一方、連続壁10の存在により、フーチング2下の地盤への地震波の侵入が抑制され、その分、地盤のせん断変形が抑制されて、地盤の液状化が未然に防止される。本実施の形態においては特に、高強度の改良柱12を、既設フーチング2の外周縁部を抱込む形態で造成しているので、既設フーチング2の外周縁部と連続壁10との間の密着(接合)が十分となり、既設フーチング2から連続壁10への荷重伝達が確実となる。
【0016】
なお、本発明は、マイクロパイル13を打設後、その芯材15の内部にグラウトを充填してもよいが、この際、さらに図3に示すように、例えばH形鋼30(▲1▼)、鋼管31(▲2▼)、棒鋼32(▲3▼)または鉄筋かご等の他の種類の補強用部材を芯材15の内部に挿入してグラウトで固めるようにしてもよい。このように補強用部材30、31、32を芯材15に挿入することで、マイクロパイル13自体の水平抵抗力(曲げ剛性)が増大し、大型の既設構造物の耐震補強としての信頼性が著しく向上するようになる。
【0017】
【発明の効果】
以上、説明したように、本発明に係る既設構造物基礎の耐震補強工法によれば、大径の改良柱とこの内部に打設したマイクロパイルとが一体となって既設フーチングを補強すると共に、これら改良柱とマイクロパイルとを含む連続壁が既設フーチング下の地盤への地震波の侵入を抑制するので、耐力増強と液状化防止との両面から耐震補強がなされることになり、信頼性が著しく向上する。
また、高圧噴射攪拌工法を利用して改良柱を造成するので、その造成に大がかりな機械設備は必要とせず、施工簡単なマイクロパイルの併用と相まって、小スペースでの工事が可能になるばかりか、工期の短縮や工費の低減も可能になり、本発明の利用価値は大なるものがある。
【図面の簡単な説明】
【図1】橋脚の耐震補強に適用した、本発明の一つの実施の形態を示す断面図である。
【図2】本発明による連続壁の造成態様を模式的に示す平面図である。
【図3】本発明における改良柱造成とマイクロパイル打設との手順を模式的に示す断面図である。
【図4】マイクロパイルに挿入する補強用部材の種類と挿入状態を示す平面図である。
【符号の説明】
1 橋脚(既設構造物)
2 既設フーチング
3 地盤
4 既設杭
5 支持地盤
6 杭基礎
10 連続壁
11 増設フーチング
12 改良柱
13 マイクロパイル
13a マイクロパイルの杭頭部
15 鋼管
16 定着層
30,31,32 補強用部材
[0001]
[Technical field to which the invention belongs]
The present invention relates to a seismic reinforcement method for enhancing the seismic resistance of foundations of existing structures such as piers and buildings.
[0002]
[Prior art]
When performing seismic reinforcement of foundations of existing structures, increasing the proof strength (supporting force) of the foundation and preventing liquefaction of the ground are important issues, and various methods for solving these two issues have hitherto been proposed. Has been developed. That is, as a method of increasing the proof stress, for example, an additional pile is constructed by placing an additional pile around the pile foundation and integrating the additional pile with the existing footing. There are methods such as adding steel pipe sheet pile foundations and integrating these with existing footings. In addition, as a method of preventing liquefaction, for example, a method of suppressing the shear deformation of the ground that occurs during an earthquake by surrounding the foundation ground with concrete walls, sheet pile walls, etc., a high-pressure jet stirring method from the bottom of the footing to the support layer There is a solidification method that improves the foundation ground by applying a solidification method such as the above.
[0003]
[Problems to be solved by the invention]
However, each of the above-mentioned construction methods has a large construction, and requires not only a wide construction space, but also has a problem that extension of construction period and increase in construction cost are inevitable.
In addition, each of the above-mentioned construction methods is effective only for either increasing the yield strength of the foundation or preventing liquefaction of the ground, and there is another problem that it is not reliable in terms of seismic reinforcement. there were.
Recently, as an additional pile of the above-described additional pile method, a method using a micropile that is easy to construct has also been developed (see, for example, Japanese Patent Laid-Open No. 10-140583). Inability to prevent this is no different from the conventional additional pile method.
[0004]
The present invention was made in order to solve the above-mentioned conventional problems, and the object of the present invention is to provide an existing structure that is easy to construct, capable of simultaneously increasing the yield strength of the foundation and preventing liquefaction of the ground. The purpose is to provide a seismic reinforcement method for building foundations.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention creates a modified column in the ground around a foundation under a footing of an existing structure by a high-pressure jet stirring method, and uses a steel pipe as a core material in the modified column. A pile is placed, and the construction of the improved pillar and the placement of the micropile are continuously performed so that the improved pillars wrap each other, and a continuous wall surrounding the foundation is constructed. The footing is added so as to wrap the pile pile head.
[0006]
In the seismic retrofitting method for existing structure foundations, the high-pressure injection stirrer method can be used to create large-diameter improved columns, and these improved columns are continuously wrapped together. Thus, a continuous wall surrounding the foundation under the footing can be easily constructed. And the presence of this continuous wall suppresses the shear deformation of the ground under the footing during an earthquake and prevents the ground from becoming liquefied.
In addition, a micropile with a steel pipe as the core material is placed in each improved pillar that constitutes this continuous wall, and the pile head of each micropile is wrapped in an additional part of the footing and integrated with the footing. , The support of the foundation itself will be sufficient.
[0007]
In the present invention, it is desirable to form the improved column in such a form as to embed the outer peripheral edge of the footing, whereby the footing and the improved column are brought into close contact with each other, and the load transmission from the footing to the improved column is ensured. .
In the present invention, it is also desirable to add a footing after connecting the pile heads of each micropile to each other, which makes the integration of the pile head and the footing of the micropile more reliable, Yield strength is further improved.
In the present invention, a reinforcing member such as an H-shaped steel, a steel pipe, or a steel bar may be inserted into the steel pipe of the micropile, thereby increasing the horizontal resistance force (bending rigidity) of the micropile itself and increasing the size. As a seismic reinforcement of existing structures, the reliability is significantly improved.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0009]
1 and 2 show one embodiment of the seismic reinforcement method according to the present invention. The present embodiment is intended for the foundation of an pier 1 as an existing structure. The pier 1 is formed on a plurality of piles 4 in which footings 2 provided integrally at the bottom of the pier 1 are placed in the ground 3. Installed and fixed in the mounted state. Each pile 4 is driven into the ground 3 until the tip of each pile reaches the support ground 5, and a plurality of the piles together constitute one pile foundation 6 and exhibit a predetermined proof strength (supporting force). It is like that. Thus, an annular continuous wall 10 is constructed around the pile foundation 6. On the other hand, on the ground surface side of the ground 3, the upper end of the continuous wall 10 and the footing of the pier 1 (existing footing). An extension footing 11 that connects and integrates 2 and 2 is constructed.
[0010]
The continuous wall 10 includes a large-diameter improved column 12 formed in the ground 3 by a high-pressure jet stirring method described later, and a micropile 13 placed in the axial center position of the improved column 12 by a method described later. The composite 14 is a unit, and a plurality of the composites 14 are connected to each other while being wrapped together. The improved pillar 12 constituting the composite 14 is constructed so as to embrace the outer peripheral edge of the existing footing 2. Accordingly, the existing footing 2 has the lower surface of the outer peripheral edge of the improved pillar of each composite 14. 12 is supported. The micropile 13 includes a hollow core material (steel pipe) 15 and a fixing layer 16 therearound. The core material 15 is firmly fixed to the improved column 12 via the fixing layer 16. On the other hand, the pile heads 13a of each micropile 13 are embedded in the extension footing 11 in a state where they are connected to each other by connecting members (not shown) such as reinforcing bars and frames. 10 and the existing footing 2 are firmly integrated via the extension footing 11.
[0011]
In carrying out this construction method, a guide hole 20 (FIG. 3) reaching the support ground 5 is drilled in the ground 3 around the pile foundation 6 in advance using a drilling machine. Then, as shown in FIG. 3, first, an injection rod 24 having an injection nozzle 23 at the tip is inserted into a steel pipe 22 having a plurality of check valves 21 on the pipe wall, and both are supported by a processor not shown. Then, it is inserted into the guide hole 20 integrally. At this time, as shown in (1) of FIG. 3, both are positioned so that the injection nozzle 23 at the tip of the injection rod 24 protrudes from the tip of the steel tube 22, and the injection rod 24 is rotated. When the injection nozzle 23 reaches the side position S 1 of the existing footing 2, a grout such as cement milk (water-cement ratio (W / C) of about 60 to 70%) is pumped into the rotating injection rod 24. To do. Then, the grout is sprayed from the injection nozzle 23 at the tip of the injection rod 24 onto the surrounding ground at a high pressure, and the ground around the steel pipe 22 is stirred and mixed by this grout to form a large-diameter stirring and mixing layer 25.
[0012]
The stirring and mixing layer 25 gradually expands downward in accordance with the lowering of the steel pipe 22 and the injection rod 24, and when the injection nozzle 23 reaches the bottom of the guide hole 20, as shown in (2) in FIG. It extends beyond the boundary S 2 between the ground 3 and the supporting ground 5 until it slightly bites into the supporting ground 5. At this stage, the grout pumping to the inflow rod 24 is stopped, and the injection rod 24 is pulled out from the steel pipe 22. Instead, the injection machine (double packer) 26 is connected to the steel pipe 22 as shown in (3) in FIG. Insert inside. The injector 26 includes a pair of bulging bodies 27 that can bulge and deform. First, the injector 26 is inserted into the deepest position of the steel pipe 22, and the pair of bulging bodies 27 are expanded at the deepest position. Then, the pouring machine 25 is fixed in position, and a hardened material grout such as cement mortar (water-cement ratio (W / C) of about 40 to 50%) is pumped through the feeding pipe 28. Then, the hardened material grout is opened around the steel pipe 22 by opening the check valve 21 on the pipe wall of the steel pipe 22, mixed into the stirring and mixing layer 25, and around the steel pipe 22, the hardened material injection layer is formed. 29 is formed. The hardener injection layer 29 expands upward by repeating the above operation while pulling up the injector 26 at a predetermined pitch, and at the stage where the injector 26 is pulled up to the side position S 1 of the existing footing 2. The injection of the grout is stopped, and the injector 26 is pulled out from the steel pipe 22 as it is.
[0013]
The stirring and mixing layer 25 and the hardened material injection layer 29 are cured after a predetermined time, and are transformed into the fixing columns 16 of the improved pillars 12 and the micropile 13, respectively, and around the pile foundation 6 as shown in FIG. In addition, one composite 14 in which the improved pillar 12 and the micropile 13 are integrated is formed. In this case, the steel pipe 22 with the check valve 21 remains as the core material 15 of the micropile 13 as it is. In the present embodiment, the formation of the composite 14 is continuously performed so that the improved pillars 12 overlap each other, and the continuous wall 10 surrounding the pile foundation 6 is constructed.
[0014]
When the creation of the continuous wall 10 is completed, first, the ground surface above this is excavated to expose the pile head 13a of the micropile 13 and the existing footing 2. Next, the pile heads 13a of each micropile 13 are connected to each other using a connecting member, and in parallel with this, the surface of the existing footing 2 is suspended, and the reinforcing bars are exposed in some cases. When a reinforcing bar is exposed, a new reinforcing bar is incorporated around the existing footing 2 in a state where the reinforcing bar is connected to a connecting member that connects the reinforcing bar and the pile head 13a, and the existing footing 2 including the pile head 13a. Put concrete around. Thereby, the extension footing 11 is constructed, and the continuous wall 10 surrounding the pile foundation 6 is firmly integrated with the existing footing 2 via the extension footing 11, and as a result, the strength of the foundation of the pier 1 as an existing structure is obtained. (Supporting force) is greatly increased and can withstand shaking during an earthquake. In the present embodiment, in particular, the grout for forming the improved column 12 has a W / C ratio of about 60 to 70%, and the grout for forming the micropile 13 has a W / C ratio of about 40 to 50%. Since it is used, the strength of the improved column 12 itself is sufficiently increased, and the bonding strength between the improved column 12 and the micropile 13 is also sufficiently increased, and the supporting force of the foundation of the pier 1 is remarkably increased.
[0015]
On the other hand, the presence of the continuous wall 10 suppresses the invasion of seismic waves into the ground below the footing 2, and the corresponding portion suppresses shear deformation of the ground, thereby preventing liquefaction of the ground. Particularly in the present embodiment, the high-strength improved column 12 is formed so as to embrace the outer peripheral edge portion of the existing footing 2, so that the adhesion between the outer peripheral edge portion of the existing footing 2 and the continuous wall 10 is established. (Joining) is sufficient, and load transmission from the existing footing 2 to the continuous wall 10 is ensured.
[0016]
In the present invention, after placing the micropile 13, the core 15 may be filled with grout. At this time, as shown in FIG. 3, for example, the H-section steel 30 ((1) ), Steel pipe 31 ({circle over (2)}), steel bar 32 ({circle over (3)}), or other types of reinforcing members such as rebar cages may be inserted into the core 15 and hardened with grout. By inserting the reinforcing members 30, 31, and 32 into the core member 15 in this way, the horizontal resistance force (bending rigidity) of the micropile 13 itself is increased, and reliability as a seismic reinforcement of a large existing structure is increased. It will be significantly improved.
[0017]
【The invention's effect】
As described above, according to the seismic reinforcement method for the existing structure foundation according to the present invention, the large-diameter improved pillar and the micropile placed inside this are integrated to reinforce the existing footing, Since the continuous wall including these improved pillars and micropile suppresses the invasion of seismic waves into the ground under the existing footing, seismic reinforcement will be made from both aspects of strengthening strength and preventing liquefaction, and the reliability is remarkably high. improves.
In addition, since the improved pillars are created using the high-pressure jet agitation method, large-scale mechanical equipment is not required for the construction, and it is possible not only to work in a small space in combination with the simple construction of the micropile. The construction period can be shortened and the construction cost can be reduced, and the utility value of the present invention is great.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing one embodiment of the present invention applied to seismic reinforcement of a bridge pier.
FIG. 2 is a plan view schematically showing a construction mode of a continuous wall according to the present invention.
FIG. 3 is a cross-sectional view schematically showing a procedure of improved column creation and micropile placement in the present invention.
FIG. 4 is a plan view showing types of reinforcing members to be inserted into the micropile and insertion states thereof.
[Explanation of symbols]
1 Pier (existing structure)
2 Existing Footing 3 Ground 4 Existing Pile 5 Support Ground 6 Pile Foundation 10 Continuous Wall 11 Additional Footing 12 Improved Pillar 13 Micropile 13a Micropile Pile Head 15 Steel Pipe 16 Fixing Layer 30, 31, 32 Reinforcing Member

Claims (4)

既設構造物のフーチング下の基礎の周りの地盤中に、高圧噴射攪拌工法により改良柱を造成すると共に、該改良柱内に鋼管を芯材とするマイクロパイルを打設し、前記した改良柱の造成とマイクロパイルの打設とを前記改良柱が相互にラップするように連続に行って、前記基礎を囲む連続壁を構築し、しかる後、前記マイクロパイルの杭頭部を包むように前記フーチングを増設することを特徴とする既設構造物基礎の耐震補強工法。In the ground around the foundation under the footing of the existing structure, an improved column is created by a high-pressure jet stirring method, and a micropile with a steel pipe as a core material is placed in the improved column, Constructing and placing the micropile continuously so that the improved pillars wrap each other to build a continuous wall surrounding the foundation, and then the footing to wrap the pile head of the micropile Seismic reinforcement method for existing structural foundations, characterized by the expansion. 改良柱を、フーチングの外周縁部を抱込む形態で造成することを特徴とする請求項1に記載の耐震補強工法。The seismic reinforcement method according to claim 1, wherein the improved column is formed in such a manner as to embrace the outer peripheral edge of the footing. 各マイクロパイルの杭頭部を相互に連結した後、フーチングを増設することを特徴とする請求項1または2に記載の耐震補強工法。The seismic reinforcement method according to claim 1 or 2 , wherein a footing is added after the pile heads of each micropile are connected to each other. マイクロパイルの鋼管内に、補強用部材を挿入することを特徴とする請求項1乃至3の何れか1項に記載の耐震補強工法。The seismic reinforcement method according to any one of claims 1 to 3 , wherein a reinforcing member is inserted into the steel pipe of the micropile.
JP07944899A 1999-03-24 1999-03-24 Seismic reinforcement method for existing structure foundation Expired - Lifetime JP3689840B2 (en)

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KR100477357B1 (en) * 2002-08-20 2005-03-22 김창근 Construction method for retaining of earth
SG103365A1 (en) * 2002-10-08 2004-04-29 Abv Engineering Pte Ltd Repairing or reinforcing building foundations
JP4571878B2 (en) * 2005-03-22 2010-10-27 五洋建設株式会社 Reinforcement method for underwater foundation of existing structure
JP2006316490A (en) * 2005-05-12 2006-11-24 Shimizu Corp Seismic strengthening structure and seismic strengthening method for pile foundation
JP4669386B2 (en) * 2005-12-15 2011-04-13 五洋建設株式会社 Reinforcement structure of foundation in existing underwater structure and its reinforcement method
CN101550705B (en) * 2008-03-31 2012-12-05 贵阳铝镁设计研究院有限公司 Reinforcement processing method of pile foundation
KR100970766B1 (en) 2008-06-16 2010-07-16 양형칠 Process for reinforcing base and preventing wash-out of earth under the bridges
JP5206333B2 (en) * 2008-11-06 2013-06-12 株式会社大林組 Ground improvement body and construction method of ground improvement body
JP5149822B2 (en) * 2009-01-22 2013-02-20 公益財団法人鉄道総合技術研究所 Reinforcement method for foundation of existing structure
JP5820677B2 (en) * 2011-09-29 2015-11-24 株式会社竹中工務店 Seismic reinforcement structure
JP2016160700A (en) * 2015-03-04 2016-09-05 東日本旅客鉄道株式会社 Foundation reinforcement method
JP6222791B1 (en) * 2017-06-29 2017-11-01 株式会社ハナミズキ・ブリッジ・プランニング Seismic reinforcement method for pier foundation and seismic reinforcement method for pier foundation
CN114775413B (en) * 2022-05-11 2023-04-11 北京建筑大学 Existing pier anti-seismic performance improving structure and method based on inertial capacity shock insulation and swing
CN114855818B (en) * 2022-05-23 2023-09-12 中铁二十局集团第一工程有限公司 Double-row narrow-distance ground wall high-pressure rotary spraying reinforcement method

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