JP2021011757A

JP2021011757A - Semi-underground foundation structure, and reinforcement method of the same

Info

Publication number: JP2021011757A
Application number: JP2019126862A
Authority: JP
Inventors: 高橋　直樹; Naoki Takahashi; 直樹高橋; 美怜渕山; Mirei Fuchiyama; 久美子春名; Kumiko Haruna
Original assignee: Sumitomo Mitsui Construction Co Ltd
Current assignee: Sumitomo Mitsui Construction Co Ltd
Priority date: 2019-07-08
Filing date: 2019-07-08
Publication date: 2021-02-04
Anticipated expiration: 2039-07-08
Also published as: JP7177754B2

Abstract

To reinforce a semi-underground foundation structure by a simpler method.SOLUTION: This invention is related to a reinforcement method of a semi-underground foundation structure 1 whose top portion 11 is exposed to the ground and a prat of whose side face 10 is exposed to the ground. The reinforcement method of the semi-underground foundation structure 1 includes: providing a reinforcement body 3 supported at the top portion 11 and facing the side face 10 exposed to the ground, the reinforcement body 3 comprising a first through hole 12 extending in a circumferential direction of the reinforcement body 3; providing a first anchor 4 supported by bedrock and passing through the first through hole 12; and tensioning the first anchor 4.SELECTED DRAWING: Figure 1

Description

本発明は半地下基礎構造物とその補強方法に関し、特に深礎杭の補強方法に関する。 The present invention relates to a semi-underground foundation structure and a method for reinforcing the same, and particularly to a method for reinforcing a deep foundation pile.

耐震性の向上などの目的で、施工された土木構造物の基礎を補強することがある。基礎の補強方法として、基礎のフーチングを増し打ちすることが知られている（特許文献１、２）。 The foundation of the constructed civil engineering structure may be reinforced for the purpose of improving earthquake resistance. As a method of reinforcing the foundation, it is known to increase the footing of the foundation (Patent Documents 1 and 2).

特開２０１２−２３７０９３公報Japanese Unexamined Patent Publication No. 2012-237093 特開平９−３１６８９２号公報Japanese Unexamined Patent Publication No. 9-316892

特許文献１、２に記載された工法は基礎自体の増し打ちやそれに伴う基礎周囲の掘削が必要である。本発明は、より簡便な半地下基礎構造物の補強方法を提供することを目的とする。 The construction methods described in Patent Documents 1 and 2 require additional striking of the foundation itself and excavation around the foundation. An object of the present invention is to provide a simpler method for reinforcing a semi-underground foundation structure.

本発明は、頂部が地上に露出するとともに側面の一部が地上に露出した半地下基礎構造物の補強方法に関する。半地下基礎構造物の補強方法は、頂部で保持されるとともに地上に露出した側面と対向する補強体であって、補強体の周方向に延びる第１の貫通孔を備える補強体を設けることと、岩盤に支持され、第１の貫通孔を通る第１のアンカーを設けることと、第１のアンカーを緊張させることと、を有する。 The present invention relates to a method for reinforcing a semi-underground foundation structure in which the top is exposed above the ground and a part of the side surface is exposed above the ground. The method of reinforcing the semi-underground foundation structure is to provide a reinforcing body that is held at the top and faces the side surface exposed on the ground and has a first through hole extending in the circumferential direction of the reinforcing body. , Supporting the bedrock, providing a first anchor through the first through hole, and tensioning the first anchor.

本発明によればより簡便な半地下基礎構造物の補強方法を提供することができる。 According to the present invention, it is possible to provide a simpler method for reinforcing a semi-underground foundation structure.

第１の実施形態に係る深礎杭の補強方法を示す概念図である。It is a conceptual diagram which shows the reinforcement method of the deep foundation pile which concerns on 1st Embodiment. 補強体の斜視図である。It is a perspective view of a reinforcing body. 第２の実施形態に係る深礎杭の補強方法を示す概念図である。It is a conceptual diagram which shows the reinforcement method of the deep foundation pile which concerns on 2nd Embodiment. 第３の実施形態に係る深礎杭の補強方法を示す概念図である。It is a conceptual diagram which shows the reinforcement method of the deep foundation pile which concerns on 3rd Embodiment. 第４の実施形態に係る深礎杭の補強方法を示す概念図である。It is a conceptual diagram which shows the reinforcement method of the deep foundation pile which concerns on 4th Embodiment. 第５の実施形態に係る深礎杭の補強方法を示す概念図である。It is a conceptual diagram which shows the reinforcement method of the deep foundation pile which concerns on 5th Embodiment.

以下、図面を参照して本発明の半地下基礎構造物の補強方法の実施形態について説明する。本発明が対象とする半地下基礎構造物は、一部が地上に露出した土木構造物である限り限定されないが、典型的には、地上設置される上部構造物を支持する基礎構造物である。本実施形態では、基礎構造物は地中深くまで施工される深礎杭であり、上部構造物は橋脚であるが、これらは基礎構造物と上部構造物の一例にすぎない。例えば、上部構造物は建物などの建築物であってもよい。本発明は既設の半地下基礎構造物を対象とするが、施工開始後に補強が必要となった半地下基礎構造物に適用することも可能である。 Hereinafter, embodiments of the method for reinforcing the semi-underground foundation structure of the present invention will be described with reference to the drawings. The semi-underground foundation structure targeted by the present invention is not limited as long as it is a civil engineering structure partially exposed above the ground, but is typically a foundation structure that supports a superstructure installed above the ground. .. In the present embodiment, the foundation structure is a deep foundation pile constructed deep underground, and the superstructure is a pier, but these are only examples of the foundation structure and the superstructure. For example, the superstructure may be a building such as a building. The present invention is intended for an existing semi-underground foundation structure, but it can also be applied to a semi-underground foundation structure that needs to be reinforced after the start of construction.

（第１の実施形態）
図１は第１の実施形態に係る深礎杭１の補強方法を示す概念図であり、図１（ａ）は深礎杭１と補強体３と第１のアンカー４を示す側方図、図１（ｂ）は、図１（ａ）のＡ−Ａ線に沿った断面図、図１（ｃ）は、図１（ａ）のＢ−Ｂ線に沿った断面図である。図２は補強体３の斜視図である。深礎杭１は斜面に設置され、その上部が地上に露出している。深礎杭１は円筒形の構造物であり、橋脚２を支持する頂部１１はほぼ円形である。深礎杭１の頂部１１は地上に露出しており、深礎杭１の少なくとも斜面下方を向く側面１０は地上に露出している。深礎杭１は補強体３と第１のアンカー４によって耐震補強される。深礎杭１に掛かる土圧は斜面の下側よりも上側のほうが大きいため、深礎杭１は斜面の下側方向に転倒する向きのモーメント（以下、下向きモーメントＭ１という）を受ける。このため、深礎杭１は地震力などが作用すると斜面の下側に傾きやすくなる。斜面の下側で表層崩壊などが生じると（破線参照）、斜面下側の土圧が減少するため、下向きモーメントＭ１がさらに増加し、深礎杭１はさらに斜面の下側に傾きやすくなる。本実施形態では、深礎杭１に保持された補強体３と、補強体３を介して深礎杭１に斜面の上側方向に転倒する向きのモーメント（以下、上向きモーメントＭ２という）を掛ける第１のアンカー４と、が設けられる。 (First Embodiment)
FIG. 1 is a conceptual diagram showing a method of reinforcing the deep foundation pile 1 according to the first embodiment, and FIG. 1 (a) is a side view showing the deep foundation pile 1, the reinforcing body 3, and the first anchor 4. 1 (b) is a cross-sectional view taken along the line AA of FIG. 1 (a), and FIG. 1 (c) is a cross-sectional view taken along the line BB of FIG. 1 (a). FIG. 2 is a perspective view of the reinforcing body 3. The deep foundation pile 1 is installed on a slope, and the upper part thereof is exposed on the ground. The deep foundation pile 1 is a cylindrical structure, and the top 11 supporting the pier 2 is substantially circular. The top 11 of the deep foundation pile 1 is exposed above the ground, and at least the side surface 10 of the deep foundation pile 1 facing downward on the slope is exposed above the ground. The deep foundation pile 1 is seismically reinforced by the reinforcing body 3 and the first anchor 4. Since the earth pressure applied to the deep foundation pile 1 is larger on the upper side than on the lower side of the slope, the deep foundation pile 1 receives a moment in the direction of tipping down on the slope (hereinafter referred to as a downward moment M1). Therefore, the deep foundation pile 1 tends to tilt downward on the slope when an earthquake force or the like acts on it. When a surface collapse occurs on the lower side of the slope (see the broken line), the earth pressure on the lower side of the slope decreases, so that the downward moment M1 further increases and the deep foundation pile 1 tends to tilt further downward on the slope. In the present embodiment, the reinforcing body 3 held by the deep foundation pile 1 and the deep foundation pile 1 are multiplied by a moment (hereinafter referred to as an upward moment M2) in the direction of tipping upward on the slope via the reinforcing body 3. Anchor 4 of 1 is provided.

補強体３は斜面の下側、すなわち深礎杭１の斜面下側を向く側面１０に設けられている。補強体３は深礎杭１の周囲の地表面の最も低い位置を中心として、深礎杭１の周囲に１８０°に渡って設けられている。補強体３は弧状の壁体３Ａとフランジ部３Ｂとを有している。壁体３Ａは側面１０に沿う内側面１６を備え、頂部１１の上方まで延びている。フランジ部３Ｂは壁体３Ａから内側に突き出し、深礎杭１の頂部１１に保持されている。フランジ部３Ｂは壁体３Ａの全周に渡って設けられる。フランジ部３Ｂは補強体３の自重の支持のために設けられるので、強度上問題がなければ、壁体３Ａに沿った周方向に間歇的に設けてもよい。補強体３は周方向に延びる第１の貫通孔１２を有し、第１の貫通孔１２には第１のアンカー４が挿入されている。第１の貫通孔１２（第１のアンカー４）は鉛直方向の互いに異なる２つのレベルに設けられているが、その数は限定されない。 The reinforcing body 3 is provided on the lower side of the slope, that is, the side surface 10 of the deep foundation pile 1 facing the lower side of the slope. The reinforcing body 3 is provided around the deep foundation pile 1 over 180 ° around the lowest position on the ground surface around the deep foundation pile 1. The reinforcing body 3 has an arc-shaped wall body 3A and a flange portion 3B. The wall body 3A has an inner side surface 16 along the side surface 10 and extends above the top 11. The flange portion 3B protrudes inward from the wall body 3A and is held by the top 11 of the deep foundation pile 1. The flange portion 3B is provided over the entire circumference of the wall body 3A. Since the flange portion 3B is provided to support the weight of the reinforcing body 3, it may be provided intermittently in the circumferential direction along the wall body 3A if there is no problem in strength. The reinforcing body 3 has a first through hole 12 extending in the circumferential direction, and a first anchor 4 is inserted into the first through hole 12. The first through holes 12 (first anchors 4) are provided at two different levels in the vertical direction, but the number is not limited.

第１のアンカー４は上方からみて、補強体３の両側の側方端面から斜面上側方向、すなわち斜面下側を向く側面１０と反対方向に延びている。第１のアンカー４は第１の部分４Ａと第２の部分４Ｂとに分割されている。第１の部分４Ａと第２の部分４ＢはＰＣ鋼材（ＰＣケーブル）からなるが、アラミド繊維や炭素繊維などからなるケーブルであってもよい。第１の部分４Ａの一部と第２の部分４Ｂの一部はそれぞれ第１の貫通孔１２に約９０°の周長に渡って挿入され、端部同士が定着具６で相互に固定されている。第１の部分４Ａの残部と第２の部分４Ｂの残部は地盤に掘削された案内孔１４に挿入され、第１の部分４Ａと第２の部分４Ｂの端部はグラウト１５で岩盤に固定されている。定着具６は第１の部分４Ａと第２の部分４Ｂを互いに固定し、第１の部分４Ａと第２の部分４Ｂを一体化させる。また、定着具６は第１の部分４Ａと第２の部分４Ｂを緊張させ、これによって第１のアンカー４全体に引張力を加える。この緊張力ないし引張力によって、補強体３に周方向のプレストレスが導入され、深礎杭１に上向きモーメントＭ２が掛けられる。定着具６の種類は特に限定されないが、一例として特許第３４３９４０３号記載の定着具を用いることができる。この定着具はＰＣ鋼材の端部を保持する２つのスリーブを一体化したもので、コンクリートに埋め込まれることによってＰＣ鋼材の引張力をコンクリートに伝達することができるようにされている。 When viewed from above, the first anchor 4 extends from the side end faces on both sides of the reinforcing body 3 toward the upper side of the slope, that is, in the direction opposite to the side surface 10 facing the lower side of the slope. The first anchor 4 is divided into a first portion 4A and a second portion 4B. The first portion 4A and the second portion 4B are made of a PC steel material (PC cable), but may be a cable made of aramid fiber, carbon fiber, or the like. A part of the first part 4A and a part of the second part 4B are each inserted into the first through hole 12 over a circumference of about 90 °, and the ends are fixed to each other by a fixing tool 6. ing. The rest of the first part 4A and the rest of the second part 4B are inserted into the guide holes 14 excavated in the ground, and the ends of the first part 4A and the second part 4B are fixed to the bedrock by grout 15. ing. The fixing tool 6 fixes the first portion 4A and the second portion 4B to each other, and integrates the first portion 4A and the second portion 4B. Further, the fixing tool 6 tensions the first portion 4A and the second portion 4B, thereby applying a tensile force to the entire first anchor 4. Due to this tension or tensile force, prestress in the circumferential direction is introduced into the reinforcing body 3, and an upward moment M2 is applied to the deep foundation pile 1. The type of the fixing tool 6 is not particularly limited, but the fixing tool described in Japanese Patent No. 3439403 can be used as an example. This fixing tool integrates two sleeves that hold the ends of the PC steel material, and is embedded in the concrete so that the tensile force of the PC steel material can be transmitted to the concrete.

上述のように、補強体３は深礎杭１の周囲に１８０°に渡って設けられているため、第１の部分４Ａと第２の部分４Ｂは互いに平行に配置される。このため、第１の部分４Ａと第２の部分４Ｂの引張力のすべてが上向きモーメントＭ２の発生に寄与する。第１の部分４Ａと第２の部分４Ｂは１８０°以外の角度をなしていてもよく、その場合、補強体３はこれに応じた角度範囲に設置される。 As described above, since the reinforcing body 3 is provided around the deep foundation pile 1 over 180 °, the first portion 4A and the second portion 4B are arranged in parallel with each other. Therefore, all the tensile forces of the first portion 4A and the second portion 4B contribute to the generation of the upward moment M2. The first portion 4A and the second portion 4B may have an angle other than 180 °, in which case the reinforcing body 3 is installed in an angle range corresponding to this.

第１の部分４Ａと第２の部分４Ｂは、第１の貫通孔１２の内部と地盤内を水平に、または水平方向に対し２０度以下の下向きの傾斜角度θで、岩盤の支持部（グラウト１５）に向けて延びている。第１の部分４Ａと第２の部分４Ｂは地盤内では直線状に延びている。換言すれば、第１のアンカー４は水平面、または水平面から２０度以下の下向きの傾斜角度θで広がる一つの平面内を延びている。第１のアンカー４の下向きの傾斜角度θが大きいと補強体３に掛かる鉛直力が大きくなり、補強体３から深礎杭１への鉛直荷重の伝達が難しくなることがある。 The first portion 4A and the second portion 4B have a downward inclination angle θ of 20 degrees or less with respect to the inside of the first through hole 12 and the ground horizontally, or a support portion (grout) of the rock mass. It extends toward 15). The first portion 4A and the second portion 4B extend linearly in the ground. In other words, the first anchor 4 extends in a horizontal plane or a plane extending from the horizontal plane at a downward tilt angle θ of 20 degrees or less. If the downward inclination angle θ of the first anchor 4 is large, the vertical force applied to the reinforcing body 3 becomes large, and it may be difficult to transmit the vertical load from the reinforcing body 3 to the deep foundation pile 1.

補強体３は周方向に複数のＰＣａ（プレキャスト）セグメント３１に分割されている。各ＰＣａセグメント３１は第１の貫通孔１２の他、周方向に延びる第２の貫通孔１３を有している。第２の貫通孔１３にはＰＣａセグメント３１に周方向のプレストレスを導入するための第２のアンカー５が挿通される。第２のアンカー５はＰＣ鋼材（ＰＣケーブル）からなるが、アラミド繊維や炭素繊維などからなるケーブルであってもよい。第２の貫通孔１３（第２のアンカー５）は補強体３の上端付近と下端付近に設けられている。第２の貫通孔１３（第２のアンカー５）の数と設置レベルは特に限定されないが、分割施工される補強体３の一体性を確保するため、第２の貫通孔１３（第２のアンカー５）は、互いに異なる複数の鉛直方向位置に設けることが好ましい。 The reinforcing body 3 is divided into a plurality of PCa (precast) segments 31 in the circumferential direction. Each PCa segment 31 has a first through hole 12 and a second through hole 13 extending in the circumferential direction. A second anchor 5 for introducing circumferential prestress into the PCa segment 31 is inserted into the second through hole 13. The second anchor 5 is made of a PC steel material (PC cable), but may be a cable made of aramid fiber, carbon fiber, or the like. The second through hole 13 (second anchor 5) is provided near the upper end and the lower end of the reinforcing body 3. The number and installation level of the second through hole 13 (second anchor 5) are not particularly limited, but in order to ensure the integrity of the reinforcing body 3 to be separately constructed, the second through hole 13 (second anchor 5) is used. 5) is preferably provided at a plurality of vertical positions different from each other.

深礎杭１の補強工事は、補強体３の設置工程と、第１のアンカー４の設置工程とを有している。補強体３の設置は以下の手順で行う。まず、複数のＰＣａセグメント３１を深礎杭１の頂部１１の所定の位置に個別に搭載し、深礎杭１にボルトなどで仮固定する。フランジ部３Ｂが深礎杭１の頂部１１に搭載され、ＰＣａセグメント３１の自重が深礎杭１で支持される。従って、仮固定は簡易なもので十分である。複数のＰＣａセグメント３１を個別に搭載するため、補強体３を仮置きする用地が少なくて済み、揚重機の容量も少なくて済む。しかし、用地や揚重機の容量に余裕がある場合、近傍のヤードで複数のＰＣａセグメント３１を一体化し、補強体３を一括搭載することも可能である。補強体３が小規模である場合、補強体３を一体で製作することもできる。この場合、第２の貫通孔１３と第２のアンカー５は不要である。補強体３は、現場でコンクリートを打設して製作してもよい。補強体３はコンクリートに限らず例えば鉄板で形成してもよい。 The reinforcement work of the deep foundation pile 1 includes an installation process of the reinforcing body 3 and an installation process of the first anchor 4. The reinforcing body 3 is installed according to the following procedure. First, a plurality of PCa segments 31 are individually mounted at predetermined positions on the top 11 of the deep foundation pile 1 and temporarily fixed to the deep foundation pile 1 with bolts or the like. The flange portion 3B is mounted on the top 11 of the deep foundation pile 1, and the weight of the PCa segment 31 is supported by the deep foundation pile 1. Therefore, a simple temporary fixing is sufficient. Since the plurality of PCa segments 31 are individually mounted, the land for temporarily placing the reinforcing body 3 is small, and the capacity of the lifting machine is also small. However, if there is a margin in the capacity of the land and the lifting machine, it is possible to integrate a plurality of PCa segments 31 in a nearby yard and collectively mount the reinforcing body 3. When the reinforcing body 3 is small in scale, the reinforcing body 3 can be integrally manufactured. In this case, the second through hole 13 and the second anchor 5 are unnecessary. The reinforcing body 3 may be manufactured by casting concrete on site. The reinforcing body 3 is not limited to concrete, and may be formed of, for example, an iron plate.

すべてのＰＣａセグメント３１を深礎杭１の所定の位置に搭載した後、第２の貫通孔１３に第２のアンカー５を挿通する。第２のアンカー５の一端を定着具７で固定し、他端をジャッキで緊張させて定着具８で固定することでＰＣａセグメント３１に周方向のプレストレスを導入する。これによってＰＣａセグメント３１同士が密着し、一体化される。この際、第２のアンカー５を仮緊張させた後に仮固定用のボルトを外し、その後第２のアンカー５を本緊張させることが好ましい。これによって、ボルトの破損や深礎杭１へのダメージを防止することができる。以上によって、補強体３が深礎杭１の地上に露出した頂部１１で保持されるともに、地上に露出した側面１０にその周方向に渡って対向することとなる。補強体３を深礎杭１に密着して接合させるため、補強体３の壁体３Ａと深礎杭１の側面１０との間、及び補強体３のフランジ部３Ｂと深礎杭１の頂部１１との間に樹脂からなる接合材９を設けることが好ましい。あるいは補強体３の壁体３Ａと深礎杭１の側面１０との間、及び補強体３のフランジ部３Ｂと深礎杭１の頂部１１との間にあらかじめ空隙を設けておき、空隙に接合材９としてモルタルを注入してもよい。接合材９は補強体３を深礎杭１に強固に固定するとともに、第１のアンカー４の引張力を深礎杭１の側面１０に均一に伝達する。 After mounting all the PCa segments 31 at predetermined positions of the deep foundation pile 1, the second anchor 5 is inserted into the second through hole 13. A circumferential prestress is introduced into the PCa segment 31 by fixing one end of the second anchor 5 with the fixing tool 7 and tensioning the other end with the fixing tool 8 and fixing it with the fixing tool 8. As a result, the PCa segments 31 are brought into close contact with each other and integrated. At this time, it is preferable that the second anchor 5 is temporarily tensioned, the temporary fixing bolt is removed, and then the second anchor 5 is fully tensioned. As a result, it is possible to prevent damage to the bolts and damage to the deep foundation pile 1. As described above, the reinforcing body 3 is held by the top portion 11 of the deep foundation pile 1 exposed above the ground, and faces the side surface 10 exposed above the ground in the circumferential direction. In order to join the reinforcing body 3 in close contact with the deep foundation pile 1, between the wall body 3A of the reinforcing body 3 and the side surface 10 of the deep foundation pile 1, and the flange portion 3B of the reinforcing body 3 and the top of the deep foundation pile 1. It is preferable to provide a bonding material 9 made of resin between the 11 and 11. Alternatively, a gap is provided in advance between the wall body 3A of the reinforcing body 3 and the side surface 10 of the deep foundation pile 1 and between the flange portion 3B of the reinforcing body 3 and the top portion 11 of the deep foundation pile 1 and joined to the gap. Mortar may be injected as the material 9. The joint member 9 firmly fixes the reinforcing body 3 to the deep foundation pile 1, and uniformly transmits the tensile force of the first anchor 4 to the side surface 10 of the deep foundation pile 1.

次に、第１のアンカー４を設置する。まず地盤に、第１の部分４Ａが挿入される第１の案内孔１４Ａと、第２の部分４Ｂが挿入される第２の案内孔１４Ｂとを掘削する。第１の案内孔１４Ａと第２の案内孔１４Ｂは岩盤まで達している。次に、第１の部分４Ａと第２の部分４Ｂを第１の貫通孔１２に挿入する。ＰＣａセグメント３１の定着具６が設けられる部位は予め切欠きとしておく。これによって、第１の貫通孔１２はその周方向の中央部付近で二分割され、中央部付近には第１の貫通孔１２の２つの開口が形成されている。第１の部分４Ａを中央部付近の一方の開口から第１の貫通孔１２の一方の半部に挿入し、この一方の半部の反対側の開口を経由して第１の案内孔１４Ａに挿入する。同様に、第２の部分４Ｂを中央部付近の他方の開口から第１の貫通孔１２の他方の半部に挿入し、この他方の半部の反対側の開口を経由して第２の案内孔１４Ｂに挿入する。次に、第１の案内孔１４Ａと第２の案内孔１４Ｂにグラウトを注入し、第１の部分４Ａと第２の部分４Ｂの端部を、グラウトを介して岩盤に定着させる。グラウト１５の定着長さは第１のアンカー４の必要引張力、岩盤の強度などによって決定する。第１のアンカー４の第１の部分４Ａは、第１の貫通孔１２の周方向の中央付近から第１の貫通孔１２の両側端部の一方の開口を通り岩盤まで延び、第２の部分４Ｂは、第１の貫通孔１２の中央付近から第１の貫通孔１２の両側端部の他方の開口を通り岩盤まで延びる。 Next, the first anchor 4 is installed. First, a first guide hole 14A into which the first portion 4A is inserted and a second guide hole 14B into which the second portion 4B is inserted are excavated in the ground. The first guide hole 14A and the second guide hole 14B reach the bedrock. Next, the first portion 4A and the second portion 4B are inserted into the first through hole 12. The portion of the PCa segment 31 where the fixing tool 6 is provided is notched in advance. As a result, the first through hole 12 is divided into two in the vicinity of the central portion in the circumferential direction, and two openings of the first through hole 12 are formed in the vicinity of the central portion. The first portion 4A is inserted into one half of the first through hole 12 from one opening near the central portion, and into the first guide hole 14A via the opening on the opposite side of the one half. insert. Similarly, the second portion 4B is inserted from the other opening near the central portion into the other half of the first through hole 12, and the second guide is passed through the opening on the opposite side of the other half. Insert into hole 14B. Next, grout is injected into the first guide hole 14A and the second guide hole 14B, and the ends of the first portion 4A and the second portion 4B are fixed to the bedrock via the grout. The anchorage length of the grout 15 is determined by the required tensile force of the first anchor 4, the strength of the bedrock, and the like. The first portion 4A of the first anchor 4 extends from the vicinity of the center in the circumferential direction of the first through hole 12 to the bedrock through one opening at both end portions of the first through hole 12, and the second portion. The 4B extends from the vicinity of the center of the first through hole 12 to the bedrock through the other opening at both side ends of the first through hole 12.

第１の部分４Ａと第２の部分４Ｂは第１の貫通孔１２の周方向の中央付近で、定着具６によって一体化される。その際、第１の部分４Ａと第２の部分４Ｂが緊張させられ引張力が加えられる。第１の部分４Ａの端部と第２の部分４Ｂの端部は補強体３の周方向中心付近で連結され、緊張させられるが、適切に引張力を掛けることができれば他の位置で連結し緊張させてもよい。すなわち、第１の貫通孔１２を周方向に二分割する位置は周方向中央部付近である必要はない。ＰＣａセグメント３１の定着具６が設けられる部位は切欠きとなっているため、外部から定着具６や緊張用のジャッキの操作が可能である。一連の作業が終わった後、切欠きがモルタル等で埋め戻され、定着具６はＰＣａセグメント３１と一体化される。第１の部分４Ａと第２の部分４Ｂは同時に緊張させることが好ましい。別々のタイミングで緊張させると深礎杭１に軸方向中心軸周りのモーメントが掛かり、深礎杭１が回転する可能性がある。ただし、鉛直方向位置の異なる第１のアンカー４は異なるタイミングで緊張させてもかまわない。 The first portion 4A and the second portion 4B are integrated by the fixing tool 6 near the center of the first through hole 12 in the circumferential direction. At that time, the first portion 4A and the second portion 4B are strained and a tensile force is applied. The end of the first portion 4A and the end of the second portion 4B are connected and tensioned near the center of the reinforcing body 3 in the circumferential direction, but if an appropriate tensile force can be applied, they are connected at other positions. You may be nervous. That is, the position where the first through hole 12 is divided into two in the circumferential direction does not have to be near the central portion in the circumferential direction. Since the portion of the PCa segment 31 where the fixing tool 6 is provided is notched, the fixing tool 6 and the jack for tension can be operated from the outside. After the series of operations is completed, the notch is backfilled with mortar or the like, and the fixing tool 6 is integrated with the PCa segment 31. It is preferable that the first portion 4A and the second portion 4B are strained at the same time. If tensions are applied at different timings, a moment around the central axis in the axial direction is applied to the deep foundation pile 1, and the deep foundation pile 1 may rotate. However, the first anchors 4 having different vertical positions may be tensioned at different timings.

本実施形態によれば、既存の深礎杭１を拡幅したり打ち増ししたりする必要がない。また、第１のアンカー４は補強体３に設けられるため、深礎杭１に穿孔する必要もない。補強体３は深礎杭１の地上部に取り付けられるため、第１のアンカー４の案内孔１４を除き地盤の掘削も不要である。さらに、補強体３は複数のＰＣａセグメント３１に分割されるため、補強体３の取り付けも短時間で済み、しかも現場に広いスペースや大容量の揚重機が不要である。特に、斜面に設置される深礎杭１は山岳部にあることが多く、スペースの確保が容易でないことが多いため、このメリットは重要である。 According to the present embodiment, it is not necessary to widen or increase the existing deep foundation pile 1. Further, since the first anchor 4 is provided on the reinforcing body 3, it is not necessary to drill the deep foundation pile 1. Since the reinforcing body 3 is attached to the above-ground portion of the deep foundation pile 1, excavation of the ground is not required except for the guide hole 14 of the first anchor 4. Further, since the reinforcing body 3 is divided into a plurality of PCa segments 31, the reinforcing body 3 can be attached in a short time, and a large space and a large-capacity lifting machine are not required at the site. In particular, the deep foundation pile 1 installed on the slope is often located in a mountainous area, and it is often difficult to secure a space, so this merit is important.

（第２の実施形態）
図３は第２の実施形態に係る深礎杭１の補強方法を示す概念図であり、図３（ａ）は深礎杭１と補強体３と第１のアンカー４を示す側方図、図３（ｂ）は、図３（ａ）のＡ−Ａ線に沿った断面図、図３（ｃ）は、図３（ａ）のＢ−Ｂ線に沿った断面図である。ここでは第１の実施形態と異なる点を中心に説明する。本実施形態では、深礎杭１は直方体の基礎構造物である。第１の実施形態と同様、補強体３は側面１０に沿う内側面１６を有するとともに頂部１１の上方まで延びる壁体３Ａと、壁体３Ａから内側に突き出し頂部１１に保持されるフランジ部３Ｂと、を有する。壁体３Ａの内側面１６は、深礎杭１の側面に合わせ矩形形状とされている。壁体３Ａと深礎杭１の側面１０との間、及びフランジ部３Ｂと深礎杭１の頂部１１との間には第１の実施形態と同様、樹脂やモルタルなどの接合材９が設けられている。フランジ部３Ｂは壁体３Ａの全周には設けられておらず、深礎杭１のコーナー部と対向する位置に設けられている。本実施形態でも第１の実施形態と同様の効果を奏することができる。 (Second Embodiment)
FIG. 3 is a conceptual diagram showing a method of reinforcing the deep foundation pile 1 according to the second embodiment, and FIG. 3A is a side view showing the deep foundation pile 1, the reinforcing body 3, and the first anchor 4. 3 (b) is a cross-sectional view taken along the line AA of FIG. 3 (a), and FIG. 3 (c) is a cross-sectional view taken along the line BB of FIG. 3 (a). Here, the points different from the first embodiment will be mainly described. In the present embodiment, the deep foundation pile 1 is a rectangular parallelepiped foundation structure. Similar to the first embodiment, the reinforcing body 3 has an inner side surface 16 along the side surface 10, a wall body 3A extending above the top portion 11, and a flange portion 3B protruding inward from the wall body 3A and held by the top portion 11. , Have. The inner side surface 16 of the wall body 3A has a rectangular shape that matches the side surface of the deep foundation pile 1. Similar to the first embodiment, a joining material 9 such as resin or mortar is provided between the wall body 3A and the side surface 10 of the deep foundation pile 1 and between the flange portion 3B and the top 11 of the deep foundation pile 1. Has been done. The flange portion 3B is not provided on the entire circumference of the wall body 3A, but is provided at a position facing the corner portion of the deep foundation pile 1. The same effect as that of the first embodiment can be obtained in this embodiment as well.

（第３の実施形態）
図４は第３の実施形態に係る深礎杭１の補強方法を示す概念図であり、図４（ａ）は深礎杭１と補強体３と第１のアンカー４を示す側方図、図４（ｂ）は、図４（ａ）のＡ−Ａ線に沿った断面図、図４（ｃ）は、図４（ａ）のＢ−Ｂ線に沿った断面図である。ここでは第１の実施形態と異なる点を中心に説明する。本実施形態では、深礎杭１は直方体の基礎構造物である。補強体３は、側面１０と対向する弧状の壁体３Ａと、壁体３Ａから内側に突き出し頂部１１に保持されるフランジ部３Ｂと、壁体３Ａを深礎杭１に接続するフレーム部材３Ｃと、を有している。壁体３Ａ及びフランジ部３Ｂは第１の実施形態の壁体３Ａ及びフランジ部３Ｂと同様の構成である。フレーム部材３Ｃは鋼材で製作される。第２の実施形態では壁体３Ａの重量が大きくなる傾向があるが、本実施形態によれば補強体３を軽量化することができる。 (Third Embodiment)
FIG. 4 is a conceptual diagram showing a method of reinforcing the deep foundation pile 1 according to the third embodiment, and FIG. 4A is a side view showing the deep foundation pile 1, the reinforcing body 3, and the first anchor 4. 4 (b) is a cross-sectional view taken along the line AA of FIG. 4 (a), and FIG. 4 (c) is a cross-sectional view taken along the line BB of FIG. 4 (a). Here, the points different from the first embodiment will be mainly described. In the present embodiment, the deep foundation pile 1 is a rectangular parallelepiped foundation structure. The reinforcing body 3 includes an arc-shaped wall body 3A facing the side surface 10, a flange portion 3B protruding inward from the wall body 3A and held by the top portion 11, and a frame member 3C connecting the wall body 3A to the deep foundation pile 1. ,have. The wall body 3A and the flange portion 3B have the same configuration as the wall body 3A and the flange portion 3B of the first embodiment. The frame member 3C is made of steel. In the second embodiment, the weight of the wall body 3A tends to be large, but according to the present embodiment, the weight of the reinforcing body 3 can be reduced.

（第４の実施形態）
図５は第４の実施形態に係る深礎杭１の補強方法を示す概念図であり、図５（ａ）は深礎杭１と補強体３と第１のアンカー４を示す側方図、図５（ｂ）は、深礎杭１と補強体３と第１のアンカー４を示す平面図である。ここでは第１の実施形態と異なる点を中心に説明する。本実施形態では、深礎杭１は平坦地に設置されている。第１のアンカー４は第１〜第４の実施形態の第１のアンカー４と同じである。平坦地であるため、深礎杭１が特定の方向に傾きやすくなることはない。このため、本実施形態では３つの第１のアンカー４が深礎杭１を中心に概ね放射状に設けられている。補強体３は深礎杭１の側面１０の全周に渡って設けられ、第２の貫通孔１３は補強体３の全周を延びている。第２のアンカー５は補強体３の全周を延びており、定着具６と同様の構成の定着具（図示せず）を用いて緊張させることができる。 (Fourth Embodiment)
FIG. 5 is a conceptual diagram showing a method of reinforcing the deep foundation pile 1 according to the fourth embodiment, and FIG. 5 (a) is a side view showing the deep foundation pile 1, the reinforcing body 3, and the first anchor 4. FIG. 5B is a plan view showing the deep foundation pile 1, the reinforcing body 3, and the first anchor 4. Here, the points different from the first embodiment will be mainly described. In this embodiment, the deep foundation pile 1 is installed on a flat land. The first anchor 4 is the same as the first anchor 4 of the first to fourth embodiments. Since it is a flat land, the deep foundation pile 1 does not easily tilt in a specific direction. Therefore, in the present embodiment, the three first anchors 4 are provided substantially radially around the deep foundation pile 1. The reinforcing body 3 is provided over the entire circumference of the side surface 10 of the deep foundation pile 1, and the second through hole 13 extends over the entire circumference of the reinforcing body 3. The second anchor 5 extends all around the reinforcing body 3, and can be tensioned by using a fixing tool (not shown) having the same structure as the fixing tool 6.

３つの第１のアンカー４は深礎杭１から互いに１２０°の角度差で延びている。第１のアンカー４の数は限定されないが、直交する２方向での耐震性が向上するよう、少なくとも３つの第１のアンカー４を設けることが好ましい。第１のアンカー４は補強体３の中心に関し回転対称の関係で設けられることが好ましい。３つの第１のアンカー４は同時に緊張させることが好ましい。第１の貫通孔１２は補強体３の全周に設けられ、補強体３のすべての周方向位置で２本の第１のアンカー４が通過する。第１の貫通孔１２は２本の第１のアンカー４が通る共通の貫通孔とすることが好ましい。その場合、１つの共通貫通孔に、３つの第１のアンカー４の両端部が挿入される計６つの開口が６０°ピッチで設けられる。第１のアンカー４毎に専用の第１の貫通孔１２を設けることもできる。 The three first anchors 4 extend from the deep foundation pile 1 with an angle difference of 120 ° from each other. The number of first anchors 4 is not limited, but it is preferable to provide at least three first anchors 4 so as to improve seismic resistance in two orthogonal directions. The first anchor 4 is preferably provided in a rotationally symmetric relationship with respect to the center of the reinforcing body 3. It is preferable that the three first anchors 4 are strained at the same time. The first through hole 12 is provided on the entire circumference of the reinforcing body 3, and the two first anchors 4 pass through the reinforcing body 3 at all circumferential positions. The first through hole 12 is preferably a common through hole through which the two first anchors 4 pass. In that case, a total of six openings into which both ends of the three first anchors 4 are inserted are provided in one common through hole at a pitch of 60 °. A dedicated first through hole 12 may be provided for each of the first anchors 4.

（第５の実施形態）
図６は第５の実施形態に係る深礎杭１の補強方法を示す概念図であり、図６（ａ）は深礎杭１と補強体３と第１のアンカー４を示す側方図、図６（ｂ）は、図６（ａ）のＡ−Ａ線に沿った断面図、図６（ｃ）は、図６（ａ）のＢ−Ｂ線に沿った断面図である。ここでは第１の実施形態と異なる点を中心に説明する。本実施形態では、第１のアンカー４の第１の部分４Ａと第２の部分４Ｂは岩盤内で一体化されている。すなわち、第１のアンカー４は１本のＰＣ鋼材からなり、第１の貫通孔１２の所定の位置から第１の貫通孔１２を通り、斜面の上側の岩盤内の案内孔１７と第１の貫通孔１２の他方の開口を通って所定の位置まで延び、両端が所定の位置で連結され緊張させられる。本実施形態では、第１のアンカー４の引張力は案内孔１７の壁面で直接支持される。このため、第１のアンカー４のモルタルでの定着が不要である。 (Fifth Embodiment)
FIG. 6 is a conceptual diagram showing a method of reinforcing the deep foundation pile 1 according to the fifth embodiment, and FIG. 6A is a side view showing the deep foundation pile 1, the reinforcing body 3, and the first anchor 4. 6 (b) is a cross-sectional view taken along the line AA of FIG. 6 (a), and FIG. 6 (c) is a cross-sectional view taken along the line BB of FIG. 6 (a). Here, the points different from the first embodiment will be mainly described. In the present embodiment, the first portion 4A and the second portion 4B of the first anchor 4 are integrated in the bedrock. That is, the first anchor 4 is made of one PC steel material, passes through the first through hole 12 from a predetermined position of the first through hole 12, and has a guide hole 17 and a first through hole 17 in the rock on the upper side of the slope. It extends through the other opening of the through hole 12 to a predetermined position, and both ends are connected and tensioned at a predetermined position. In this embodiment, the tensile force of the first anchor 4 is directly supported by the wall surface of the guide hole 17. Therefore, it is not necessary to fix the first anchor 4 with the mortar.

１半地下基礎構造物（深礎杭）
３補強体
３Ａ壁体
３Ｂフランジ部
３Ｃフレーム部材
４第１のアンカー
４Ａ第１の部分
４Ｂ第２の部分
５第２のアンカー
９接合材
１０側面
１１頂部
１２第１の貫通孔
１３第２の貫通孔
３１ＰＣａセグメント 1 Semi-underground foundation structure (deep foundation pile)
3 Reinforcing body 3A Wall body 3B Flange part 3C Frame member 4 First anchor 4A First part 4B Second part 5 Second anchor 9 Joint material 10 Side surface 11 Top 12 First through hole 13 Second penetration Hole 31 PCa segment

Claims

It is a method of reinforcing a semi-underground foundation structure with the top exposed above the ground and part of the sides exposed above the ground.
To provide a reinforcing body that is held at the top and faces the side surface exposed to the ground and has a first through hole extending in the circumferential direction of the reinforcing body.
To provide a first anchor that is supported by the bedrock and passes through the first through hole.
A method of reinforcing a semi-underground foundation structure comprising tensioning the first anchor.

The semi-underground foundation structure is installed on a slope, at least a part of a side surface facing downward on the slope is exposed, the reinforcing body is provided on the exposed side surface, and the first anchor is attached to the exposed side surface. The method for reinforcing a semi-underground foundation structure according to claim 1, which extends to the opposite side.

The first anchor includes a first portion extending from a predetermined position of the first through hole to the bedrock through one opening of the first through hole, and the first through hole from the predetermined position. 2. A second portion extending through the other opening of the rock to the bedrock, wherein the first portion and the second portion are fixed to the bedrock and then tensioned at the predetermined position. Reinforcement method of semi-underground foundation structure described in.

The first anchor passes through the first through hole from a predetermined position of the first through hole, and passes through the guide hole in the bedrock and the other opening of the first through hole to the predetermined position. The method for reinforcing a semi-underground foundation structure according to claim 2, wherein both ends are tensioned at the predetermined positions.

The semi-underground foundation structure is installed on a flat ground, the reinforcing body is provided over the entire circumference of the side surface of the semi-underground foundation structure, and a plurality of the first anchors are provided from the semi-underground foundation structure. The method for reinforcing a semi-underground foundation structure according to claim 1, which extends in different directions.

The method for reinforcing a semi-underground foundation structure according to claim 5, wherein the plurality of first anchors are provided in a rotationally symmetric relationship with respect to the center of the semi-underground foundation structure.

The reinforcing body has a plurality of PCa segments divided in the circumferential direction, and each PCa segment has a second through hole extending in the circumferential direction.
The invention according to any one of claims 1 to 6, wherein a second anchor for introducing circumferential prestress is provided in the plurality of PCa segments through the second through hole of the plurality of PCa segments. How to reinforce a semi-underground foundation structure.

The method for reinforcing a semi-underground foundation structure according to claim 7, wherein at least one of the first anchor and the second anchor is provided at different vertical positions of the reinforcing body.

The semi-underground foundation according to any one of claims 1 to 8, wherein the first anchor extends horizontally or at a downward angle of 20 degrees or less with respect to the horizontal direction toward a rock support portion. How to reinforce the structure.

The method for reinforcing a semi-underground foundation structure according to any one of claims 1 to 9, wherein a joining material made of mortar or resin is provided between the reinforcing body and the semi-underground foundation structure.

The semi-underground foundation structure has a cylindrical or rectangular parallelepiped shape, and the reinforcing body has an inner surface along the side surface of the semi-underground foundation structure, and a wall body extending above the top and the wall. The method for reinforcing a semi-underground foundation structure according to any one of claims 1 to 10, further comprising a flange portion protruding inward from the body and held at the top.

The semi-underground foundation structure has a rectangular parallelepiped shape, and the reinforcing body has an arc-shaped wall body facing the side surface and a frame member connecting the wall body to the semi-underground foundation structure. The method for reinforcing a semi-underground foundation structure according to any one of claims 1 to 10.

The method for reinforcing a semi-underground foundation structure according to claim 11 or 12, wherein the semi-underground foundation structure is a deep foundation pile that supports a pier.

A semi-underground foundation structure with the top exposed above the ground and part of the sides exposed above the ground.
A reinforcing body held at the top and facing the side surface exposed to the ground, and having a first through hole extending in the circumferential direction of the reinforcing body.
A semi-underground foundation structure having a first anchor that is supported by the bedrock, passes through the first through hole, and is strained.