JP5407644B2 - Underground continuous wall foundation made difficult to be affected by lateral flow of the ground, and its construction method - Google Patents

Underground continuous wall foundation made difficult to be affected by lateral flow of the ground, and its construction method Download PDF

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JP5407644B2
JP5407644B2 JP2009180997A JP2009180997A JP5407644B2 JP 5407644 B2 JP5407644 B2 JP 5407644B2 JP 2009180997 A JP2009180997 A JP 2009180997A JP 2009180997 A JP2009180997 A JP 2009180997A JP 5407644 B2 JP5407644 B2 JP 5407644B2
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continuous wall
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峰生 佐藤
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Obayashi Corp
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Description

本発明は、地盤を構成する土砂による側方流動の影響を受け難くした構造を有する地中連続壁基礎、及び、その構築方法に関する。 The present invention relates to an underground continuous wall foundation having a structure that is hardly affected by lateral flow caused by earth and sand constituting the ground , and a construction method thereof .

構造物の基礎として地中連続壁を杭のように使用する地中連続壁基礎がある。この手法では、単純な施工で、基礎の支持力を分担する面積を大きく確保することができ、基礎の剛性を高めることができる。   There is an underground continuous wall foundation that uses the underground continuous wall like a pile as the foundation of the structure. With this method, a simple construction can secure a large area for sharing the supporting force of the foundation, and the rigidity of the foundation can be increased.

一方、構造物背面に盛土がある場合や前面が護岸になっている場合には、基礎周辺の地盤は前面に押し出されるような力を受けている。このため、基礎周辺の地盤が軟弱粘性土の場合には、側方に変位しようとする流動圧が基礎に作用する。また、基礎周辺の地盤が緩い砂地盤で、地震により液状化した場合には、地盤を構成する土砂が側方に流動する（特許文献１を参照）。
このように、側方流動の影響としては、（１）基礎周辺の地盤が軟弱性地盤の場合における側方に変位しようとする流動圧、（２）基礎周辺の地盤が緩い砂地盤の場合に、地震による液状化で側方流動する流動力がある。 On the other hand, when there is embankment on the back of the structure or when the front is a revetment, the ground around the foundation receives a force that pushes it out to the front. For this reason, when the ground around the foundation is soft and viscous soil, the fluid pressure to be displaced laterally acts on the foundation. Moreover, when the ground around the foundation is a loose sand ground and is liquefied by an earthquake, the earth and sand constituting the ground flow to the side (see Patent Document 1).
In this way, the effects of lateral flow are as follows: (1) Fluid pressure that tends to displace laterally when the ground around the foundation is soft, and (2) When the ground around the foundation is loose sand There is a fluid force that flows laterally due to liquefaction caused by earthquakes.

これらの側方流動による影響は地中連続壁基礎でも同様に作用し、基礎構造の面積が大きい分、地中連続壁基礎ではより大きな影響を受けることも考えられる。   The effects of these lateral flows also work on the underground wall foundation in the same way, and it is also possible that the foundation wall will be affected more by the large area of the foundation structure.

上記の側方流動の影響を抑制する技術として、次のものが提案されている。
（１）湾曲させた地中連続壁を用いて基礎構造物を囲み、側方流動圧を逃がすもの（特許文献２を参照）。
（２）狭幅側面が外方に位置する向きで、対象構造物を囲むように、複数の連続壁を設けるもの（特許文献３を参照）。
（３）流線型をした分流構造体を、基礎フーチングにおける側方流動方向との対向位置に設けるもの（特許文献４を参照）。 The following has been proposed as a technique for suppressing the influence of the lateral flow.
(1) A structure that surrounds the foundation structure using a curved underground continuous wall to release the lateral flow pressure (see Patent Document 2).
(2) A structure in which a plurality of continuous walls are provided so as to surround the target structure in a direction in which the narrow side surface is located outward (see Patent Document 3).
(3) A streamlined shunt structure is provided at a position facing the lateral flow direction in the basic footing (see Patent Document 4).

特開平１１−６１８４８号公報JP-A-11-61848 特開平１０−１８３１２号公報JP-A-10-18312 特開平１０−２１９６７６号公報Japanese Patent Laid-Open No. 10-219676 特開２００４−２７０２０７号公報JP 2004-270207 A

しかしながら、これらの技術は、対象となる構造物に対して側方流動が作用しないように保護するものであるため、施工が大掛かりになってしまう。   However, since these technologies protect the target structure from the side flow, the construction becomes large.

本発明は、上記のような従来の問題に鑑みなされたものであって、地盤の側方流動の影響を受け難くしながらも、施工が容易な地中連続壁基礎を提供することを目的とするものである。   The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an underground continuous wall foundation that is easy to be constructed while being hardly affected by the lateral flow of the ground. To do.

本発明は、基礎を構成する地中連続壁を、その壁面が土砂の側方流動方向に対して略平行となる向きに設けた地中連続壁基礎であって、前記地中連続壁における前記側方流動方向の上流側端部は、前記壁体の上側部分にて上流側へ向かう程に狭幅となっており、下側部分にて矩形状となっていることを特徴とする。 The present invention is an underground continuous wall foundation in which the underground continuous wall constituting the foundation is provided in a direction in which the wall surface is substantially parallel to the lateral flow direction of the earth and sand. The upstream end in the lateral flow direction is narrower toward the upstream side in the upper part of the wall body, and is rectangular in the lower part.

本発明によれば、側方流動が生じた場合において、土砂は、地中連続壁の端面に向かって流れる。そして、地中連続壁における側方流動方向の上流側端部に関し、壁体の上側部分を上流側へ向かう程に狭幅にし、下側部分を矩形状にしているので、土砂の側方流動が生じやすい上側部分について選択的に流動圧を軽減でき、下側部分については断面積の欠損がないので支持力を確保できる。また、地中連続壁を基本構成としているので、地盤の側方流動の影響を受け難くしながらも、構造の簡素化が図れるとともに施工が容易である。 According to the present invention, when side flow occurs, the earth and sand flows toward the end face of the underground continuous wall. And, with respect to the upstream side end portion in the lateral flow direction in the underground continuous wall, the upper portion of the wall is made narrower toward the upstream side, and the lower portion is rectangular, so that the lateral flow of earth and sand Therefore, it is possible to selectively reduce the flow pressure in the upper part that is likely to cause a failure, and it is possible to secure a supporting force because there is no loss in the cross-sectional area in the lower part. In addition, since the underground continuous wall is a basic configuration, the structure can be simplified and the construction is easy while being hardly affected by the lateral flow of the ground.

また、本発明の地中連続壁基礎の構築方法は、地中に掘削溝を形成し、この掘削溝に鉄筋籠を建て込み、側方流動方向の上流側に位置する前記鉄筋籠の端部に、上流側へ向かう程に狭幅となる型枠を設け、掘削溝にコンクリートを打設することを特徴とする。
本発明によれば、打設されたコンクリートが型枠に倣って硬化し、地中連続壁の端部を所望の形状に設けることができる。 Moreover, the construction method of the underground continuous wall foundation of the present invention includes forming an excavation groove in the ground, building a reinforcing bar in the excavation groove, and an end of the reinforcing bar located on the upstream side in the lateral flow direction. In addition, a mold that becomes narrower toward the upstream side is provided, and concrete is placed in the excavation groove.
According to the present invention, the placed concrete hardens following the formwork, and the end of the underground continuous wall can be provided in a desired shape.

本発明によれば、構造の簡素化が図れ、地盤の側方流動の影響を受け難くしながらも、施工が容易な地中連続壁基礎を提供できる。   ADVANTAGE OF THE INVENTION According to this invention, the simplification of a structure can be achieved and the underground continuous wall foundation which is easy to construct can be provided, although it is hard to receive the influence of the lateral flow of a ground.

地中連続壁基礎を説明する図であり、（ａ）は地中に埋設された状態を説明する図、（ｂ）は平面図である。It is a figure explaining an underground continuous wall foundation, (a) is a figure explaining the state embed | buried under the ground, (b) is a top view. 土砂の側方流動を説明する模式図である。It is a schematic diagram explaining the lateral flow of earth and sand. 掘削溝の形成を説明する図であり、（ａ）は初回の掘削を説明する図、（ｂ）は初回の掘削で形成された縦溝の平面図、（ｃ）は掘削を複数回行った状態を説明する図、（ｄ）は複数回の掘削で形成された溝の平面図である。It is a figure explaining formation of a digging groove, (a) is a figure explaining the first excavation, (b) is a top view of the longitudinal groove formed by the first excavation, (c) was excavated several times. FIG. 4D is a plan view of a groove formed by a plurality of excavations. （ａ）及び（ｂ）は、鉄筋籠の建込みを説明する図である。(A) And (b) is a figure explaining the erection of a reinforcing bar. （ａ）〜（ｃ）は、コンクリートの打設等を説明する図である。(A)-(c) is a figure explaining placement of concrete. 第２実施形態の説明図であり、（ａ）は地中に埋設された状態を説明する図、（ｂ）は連続壁の外観斜視図、（ｃ）はＡ−Ａ矢視図である。It is explanatory drawing of 2nd Embodiment, (a) is a figure explaining the state embed | buried under the ground, (b) is an external appearance perspective view of a continuous wall, (c) is an AA arrow directional view. 第２実施形態での施工を説明する図であり、（ａ）は回転式掘削機による初回の掘削を説明する図、（ｂ）は初回の掘削で形成された縦溝の平面図、（ｃ）はバケット式掘削機による仕上げの掘削を説明する図、（ｄ）は仕上げの掘削で形成された溝の平面図である。It is a figure explaining construction in a 2nd embodiment, (a) is a figure explaining the first excavation by a rotary excavator, (b) is a top view of the vertical groove formed by the first excavation, (c) ) Is a diagram for explaining finishing excavation by a bucket excavator, and (d) is a plan view of a groove formed by finishing excavation. 第３実施形態の説明図であり、連続壁の断面形状を説明する図である。It is explanatory drawing of 3rd Embodiment, and is a figure explaining the cross-sectional shape of a continuous wall. 第３実施形態の連続壁を施工する際に用いられる鉄筋籠及び型枠を説明する外観斜視図である。It is an external appearance perspective view explaining the reinforcing bar cage and formwork used when constructing the continuous wall of a 3rd embodiment. 第３実施形態での施工を説明する図であり、（ａ）はコンクリートの打設を説明する断面図、（ｂ）は同じく平面図である。It is a figure explaining construction in a 3rd embodiment, (a) is a sectional view explaining placement of concrete, and (b) is a top view similarly. 第４実施形態の連続壁を説明する外観斜視図である。It is an external appearance perspective view explaining the continuous wall of 4th Embodiment. 第４実施形態の連続壁を施工する際に用いられる鉄筋籠及び型枠を説明する外観斜視図である。It is an external appearance perspective view explaining the rebar rod and formwork used when constructing the continuous wall of a 4th embodiment. 第４実施形態での施工を説明する図であり、（ａ）はコンクリートの打設を説明する断面図、（ｂ）は同じく平面図である。It is a figure explaining construction in a 4th embodiment, (a) is a sectional view explaining placement of concrete, and (b) is a top view similarly.

以下、本発明の好ましい実施形態について図面を用いて詳細に説明する。   Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

−−−第１実施形態−−−
図１（ａ），（ｂ）に示すように、地中連続壁基礎１は、複数の連続壁２を有する平行複壁式である。この実施形態において、連続壁２は４枚であり、各連続壁２の上面２３に、構造物本体（橋梁下部工）３が有するフーチング３２を接合している。本実施形態において、フーチング３２は、地中連続壁基礎１の一部を構成している。各連続壁２は、鉄筋コンクリートで作製された矩形板状であり、地中に埋設される。寸法はそれぞれの連続壁２で同じであり、例えば壁面２１の幅Ｗ１が６ｍ〜８ｍ、端面２２の幅（すなわち連続壁２の厚さ）Ｗ２が１〜２ｍ、高さ（深さ）が３０ｍ〜５０ｍとされ、図２（ａ）に示すように、各連続壁２は、粘性土の層や砂質土の層を貫いた状態で設けられる。各連続壁２は、壁面２１が互いに平行となる向きで、或る連続壁２の壁面２１と隣の連続壁２の壁面２１とが対向する状態で配置される。また、各連続壁２は、所定間隔Ｌ毎に配置される。この間隔Ｌは、連続壁２同士の間を土砂が円滑に流れる大きさに定められ、例えば４〜５ｍである。 --- First Embodiment ---
As shown in FIGS. 1A and 1B, the underground continuous wall foundation 1 is a parallel double-walled type having a plurality of continuous walls 2. In this embodiment, there are four continuous walls 2, and the footings 32 of the structural body (bridge substructure) 3 are joined to the upper surface 23 of each continuous wall 2. In the present embodiment, the footing 32 constitutes a part of the underground continuous wall foundation 1. Each continuous wall 2 has a rectangular plate shape made of reinforced concrete and is buried in the ground. The dimensions are the same for each continuous wall 2. For example, the width W1 of the wall surface 21 is 6 m to 8 m, the width of the end face 22 (that is, the thickness of the continuous wall 2) W2 is 1 to 2 m, and the height (depth) is 30 m. 2 m, each continuous wall 2 is provided in a state of penetrating a layer of viscous soil or a layer of sandy soil. Each continuous wall 2 is arranged in a state in which the wall surfaces 21 are parallel to each other, and the wall surface 21 of a certain continuous wall 2 and the wall surface 21 of the adjacent continuous wall 2 face each other. Moreover, each continuous wall 2 is arrange | positioned for every predetermined space | interval L. FIG. The distance L is determined to be a size that allows the earth and sand to smoothly flow between the continuous walls 2 and is, for example, 4 to 5 m.

構造物本体３は、壁状部分３１とフーチング３２とを有している。例示したフーチング３は、各連続壁２の上面２３を覆う大きさの板状であり、フーチング内Ｗ１に各連続壁２が配置されている。壁状部分３１は、連続壁２の並び方向（上面２３における長手方向と直交する方向）と略平行に設けられている。なお、壁状部分３１の取付方向は、この方向に限定されない。   The structure main body 3 has a wall-shaped portion 31 and a footing 32. The illustrated footing 3 is a plate having a size covering the upper surface 23 of each continuous wall 2, and each continuous wall 2 is disposed in the footing W <b> 1. The wall-shaped portion 31 is provided substantially parallel to the direction in which the continuous walls 2 are arranged (the direction perpendicular to the longitudinal direction on the upper surface 23). In addition, the attachment direction of the wall-shaped part 31 is not limited to this direction.

この地中連続壁基礎１では、連続壁２が土砂の側方流動方向に応じた向きに構築される。すなわち、岸壁付近や河岸、或いは、背面盛土の施工箇所では、図１に符号Ｆ１の矢印で示すように、地盤の高低差に起因して、土砂が低い側へ流動し易い性質を有する。そこで、本実施形態では、壁面２１が土砂の流動し易い方向と略平行となる向き（言い換えれば、端面２２が土砂の流動し易い方向と対向する向き）に連続壁２を構築している。   In this underground continuous wall foundation 1, the continuous wall 2 is constructed in a direction according to the lateral flow direction of earth and sand. That is, in the vicinity of the quay, on the riverbank, or on the back embankment, as shown by the arrow F1 in FIG. 1, the soil tends to flow to the lower side due to the height difference of the ground. Therefore, in the present embodiment, the continuous wall 2 is constructed in a direction in which the wall surface 21 is substantially parallel to the direction in which the earth and sand easily flow (in other words, the direction in which the end surface 22 faces the direction in which the earth and sand easily flows).

ここで、土砂の側方流動が生じた場合における地中連続壁基礎１の作用について説明する。図２（ａ）に示す方向Ｆ２に側方流動が生じた場合を例に挙げて説明する。この場合、土砂の一部は連続壁２の端面２２に向かって流れてくる。端面２２の面積は、壁面２１の面積よりも十分に小さい。このため、連続壁２にかかる流動圧を抑えることができ、側方流動の影響を受け難くすることができる。また、連続壁２における地盤との接触部分の面積を十分確保でき、地盤との間の摩擦力を高められる。従って、連続壁２において、土砂の側方流動に対する抗力を一層大きくできる。その結果、連続壁２の過度な変位や損傷を抑えることができる。   Here, the effect | action of the underground continuous wall foundation 1 when the side flow of earth and sand arises is demonstrated. The case where a lateral flow occurs in the direction F2 shown in FIG. 2A will be described as an example. In this case, part of the earth and sand flows toward the end face 22 of the continuous wall 2. The area of the end surface 22 is sufficiently smaller than the area of the wall surface 21. For this reason, the flow pressure concerning the continuous wall 2 can be suppressed and it can be made hard to receive the influence of a side flow. Moreover, the area of the contact part with the ground in the continuous wall 2 can be ensured enough, and the frictional force between the grounds can be raised. Therefore, in the continuous wall 2, the resistance against the lateral flow of earth and sand can be further increased. As a result, excessive displacement and damage of the continuous wall 2 can be suppressed.

次に、地中連続壁基礎１の構築方法について説明する。地中連続壁基礎１を構築するに際しては、まず、地中に複数の連続壁２を構築する。この場合、例えば図３（ａ），（ｂ）に示すように、回転式掘削機４１を下降させて開口が矩形状の縦溝Ｈ１を掘削する。なお、縦溝Ｈ１の内壁が崩れることを抑制するため、縦溝Ｈ１の内部を安定液ＬＱで満たしておく。縦溝Ｈ１を所定深さまで掘削したならば、回転式掘削機４１を地上まで引き上げる。これらの作業を繰り返し、１つのエレメントに対応する大きさの縦溝Ｈ１を形成する。その結果、図３（ｃ），（ｄ）に示すように、長手方向が側方流動方向に平行な長方形状の開口を有し、十分な壁面方向の長さと深さを有する直方体状の掘削溝Ｈ２が形成される。   Next, the construction method of the underground continuous wall foundation 1 will be described. When constructing the underground continuous wall foundation 1, first, a plurality of continuous walls 2 are constructed in the ground. In this case, for example, as shown in FIGS. 3A and 3B, the rotary excavator 41 is lowered to excavate a vertical groove H1 having a rectangular opening. In order to prevent the inner wall of the longitudinal groove H1 from collapsing, the interior of the longitudinal groove H1 is filled with the stabilizing liquid LQ. When the longitudinal groove H1 is excavated to a predetermined depth, the rotary excavator 41 is pulled up to the ground. By repeating these operations, the vertical groove H1 having a size corresponding to one element is formed. As a result, as shown in FIGS. 3C and 3D, a rectangular parallelepiped excavation having a rectangular opening whose longitudinal direction is parallel to the lateral flow direction and having a sufficient length and depth in the wall surface direction. A groove H2 is formed.

掘削溝Ｈ２の形成後、鉄筋籠２４の建込みを行う。この場合、図４（ａ）に示すように、鉄筋籠２４をクレーンで吊し、掘削溝Ｈ２の真上に配置する。その後、鉄筋籠２４を徐々に下降させ、図４（ｂ）に示すように、鉄筋籠２４の下端が底面に達しない所定の高さで下降を止め、開口上に設置したガイド金物（図示せず）から吊り下げて固定する。次に、鉄筋籠２４が配置された掘削溝Ｈ２にトレミー管４２（図５（ａ）を参照）を挿入し、トレミー管４２の先端が掘削溝Ｈ２の底面付近に達したらトレミー管４２を通じてコンクリート２５を注入する。これにより、安定液ＬＱよりも比重の大きいコンクリート２５は、掘削溝Ｈ２の最下部から上方に向けて充填される。図５（ａ）は、掘削溝Ｈ２の中間高さまでコンクリート２５が充填された状態を示している。図５（ｂ）に示すように、所定高さまでコンクリート２５を充填したならば養生する。これにより、コンクリート２５が硬化して連続壁２が構築される。   After the formation of the excavation groove H2, the reinforcing bar 24 is installed. In this case, as shown in FIG. 4 (a), the reinforcing bar 24 is suspended by a crane and placed just above the excavation groove H2. Thereafter, the rebar rod 24 is gradually lowered, and as shown in FIG. 4B, the lower end of the rebar rod 24 stops at a predetermined height that does not reach the bottom surface, and the guide hardware (not shown) installed on the opening is shown. )) And fix it. Next, the tremmy pipe 42 (see FIG. 5A) is inserted into the excavation groove H2 in which the reinforcing bar 24 is disposed, and when the tip of the tremy pipe 42 reaches the vicinity of the bottom of the excavation groove H2, the concrete is passed through the tremy pipe 42. 25 is injected. As a result, the concrete 25 having a specific gravity greater than that of the stabilizing liquid LQ is filled upward from the bottom of the excavation groove H2. FIG. 5A shows a state in which the concrete 25 is filled up to the intermediate height of the excavation groove H2. As shown in FIG.5 (b), if the concrete 25 is filled to predetermined height, it will be cured. Thereby, the concrete 25 hardens | cures and the continuous wall 2 is constructed | assembled.

上述した掘削溝Ｈ２の形成、鉄筋籠２４の建込み、及び、コンクリート２５の打設を、連続壁２の数に対応する分だけ行い、必要数の連続壁２を構築する。すべての連続壁２を構築したならば、図５（ｃ）に示すように、各連続壁２の上面２３に構造物本体３を構築する。これにより、地中連続壁基礎１の構築が完了する。   The necessary number of continuous walls 2 is constructed by forming the excavation groove H2 described above, installing the reinforcing bar 24, and placing the concrete 25 as much as the number of the continuous walls 2. When all the continuous walls 2 are constructed, the structure body 3 is constructed on the upper surface 23 of each continuous wall 2 as shown in FIG. Thereby, the construction of the underground continuous wall foundation 1 is completed.

−−−第２実施形態−−−
前述の第１実施形態では、各連続壁２における側方流動方向の上流側端部は、平面視で矩形状であるものとした。このような矩形状端部の場合、上流側から流れる土砂が、連続壁２における端面２２を直接的に押圧し、土砂の流動圧がそのまま端面２２に作用してしまう。第２実施形態は、このような事情に鑑みてなされたものであり、連続壁２に作用する流動圧を軽減することを目的としている。 --- Second Embodiment ---
In the first embodiment described above, the upstream end portion of each continuous wall 2 in the lateral flow direction is rectangular in plan view. In the case of such a rectangular end, the earth and sand flowing from the upstream side directly presses the end face 22 in the continuous wall 2, and the fluid pressure of the earth and sand acts on the end face 22 as it is. The second embodiment has been made in view of such circumstances, and aims to reduce the fluid pressure acting on the continuous wall 2.

第２実施形態の地中連続壁基礎は、連続壁の上流側端部の形状に特徴を有する。図６（ａ），（ｂ）に示すように、上流側端部２２Ａは、上下方向の全体に亘って、側方流動方向の上流側に向かうほどに幅が狭くなるように構成されている。具体的には、上流側端部２２Ａを曲面とし、平面視で半円形状に構成している。なお、他の部分については、前述した第１実施形態の地中連続壁基礎１と同様である。このため、説明は省略する。   The underground continuous wall foundation of the second embodiment is characterized by the shape of the upstream end of the continuous wall. As shown in FIGS. 6 (a) and 6 (b), the upstream end 22A is configured to be narrower toward the upstream side in the lateral flow direction over the entire vertical direction. . Specifically, the upstream end 22A has a curved surface and is formed in a semicircular shape in plan view. In addition, about another part, it is the same as that of the underground continuous wall foundation 1 of 1st Embodiment mentioned above. Therefore, the description is omitted.

このように、上流側端部２２Ａを曲面で構成することで、土砂からの流動圧を緩和できる。すなわち、図６（ｃ）に示すように、側方流動する土砂が上流側端部２２Ａに到達すると、この土砂は上流側端部２２Ａの曲面に沿って流れの方向を変える。すなわち、土砂は、連続壁２Ａを逃げるように分流される。これに伴い、連続壁２Ａに作用する流動圧を軽減することができ、この土砂を壁面２１に沿って流すことができる。その結果、地盤の側方流動の影響を受け難くすることができる。   Thus, the flow pressure from earth and sand can be relieved by comprising upstream end part 22A with a curved surface. That is, as shown in FIG. 6C, when the earth and sand flowing laterally reach the upstream end 22A, the sediment changes the flow direction along the curved surface of the upstream end 22A. That is, the earth and sand are diverted so as to escape the continuous wall 2A. Accordingly, the fluid pressure acting on the continuous wall 2A can be reduced, and the earth and sand can be flowed along the wall surface 21. As a result, it can be made less susceptible to the lateral flow of the ground.

次に、第２実施形態の地中連続壁基礎１の構築について説明する。第２実施形態の地中連続壁基礎１の構築手順は、基本的に第１実施形態で説明した構築手順と同様である。第１実施形態における構築手順との相違は、主に、連続壁２Ａを構築するための掘削溝の形状にある。そこで、この溝を中心に説明をする。   Next, construction of the underground continuous wall foundation 1 of the second embodiment will be described. The construction procedure of the underground continuous wall foundation 1 of the second embodiment is basically the same as the construction procedure described in the first embodiment. The difference from the construction procedure in the first embodiment is mainly in the shape of the excavation groove for constructing the continuous wall 2A. Therefore, this groove will be mainly described.

第２実施形態の場合も、例えば図７（ａ），（ｂ）に示すように、回転式掘削機４１を下降させて開口が矩形状の縦溝Ｈ１を掘削する。そして、回転式掘削機４１の位置を、側方流動の上流側に順次ずらして掘削をすることで、長方形状の開口を有する溝を形成する。そして、図７（ｃ），（ｄ）に示すように、仕上げ時の掘削でバケット４３を用い、上流側端部が平面視で半円形状となった掘削溝Ｈ３を形成する。   Also in the case of the second embodiment, for example, as shown in FIGS. 7A and 7B, the rotary excavator 41 is lowered to excavate a vertical groove H1 having a rectangular opening. And the groove | channel which has a rectangular-shaped opening is formed by shifting and excavating the position of the rotary excavator 41 to the upstream side of a side flow one by one. 7 (c) and 7 (d), the bucket 43 is used for excavation at the time of finishing, and the excavation groove H3 whose upstream end is semicircular in plan view is formed.

後の手順は第１実施形態と同様である。簡単に説明すると、掘削溝Ｈ３に鉄筋籠２４を建込み、コンクリート２５を打設することで、複数の連続壁２Ａを構築する。その後、各連続壁２Ａの上面２３に構造物本体３を設け、地中連続壁基礎１を構築する。   The subsequent procedure is the same as in the first embodiment. Briefly, a plurality of continuous walls 2A are constructed by installing a reinforcing bar 24 in the excavation groove H3 and placing concrete 25 therein. Then, the structure main body 3 is provided on the upper surface 23 of each continuous wall 2A, and the underground continuous wall foundation 1 is constructed.

なお、第２実施形態では、連続壁２の上流側端部が平面視で半円形状に形成されていたが、これに限定されない。例えば、平面視で楕円形状に形成されていてもよい。要するに、上流側へ向かう程に狭幅となっている曲面形状であればよい。   In addition, in 2nd Embodiment, although the upstream edge part of the continuous wall 2 was formed in semicircle shape by planar view, it is not limited to this. For example, it may be formed in an elliptical shape in plan view. In short, it may be a curved surface shape that becomes narrower toward the upstream side.

−−−第３実施形態−−−
前述の第２実施形態において、連続壁２Ａの上流側端部２２Ａは、平面視で半円形状や楕円形状に形成されていた。言い換えれば、上流側の端面２２が湾曲面によって構成されていた。しかし、本発明は、この構成に限定されるものではない。例えば、連続壁の上流側端部を、平面視で先尖状に形成してもよい。以下、このようにした第３実施形態について説明する。 --- Third Embodiment ---
In the second embodiment described above, the upstream end 22A of the continuous wall 2A is formed in a semicircular shape or an elliptical shape in plan view. In other words, the upstream end surface 22 is configured by a curved surface. However, the present invention is not limited to this configuration. For example, you may form the upstream edge part of a continuous wall in the shape of a point by planar view. Hereinafter, the third embodiment configured as described above will be described.

図８は、第３実施形態の要部を説明する図であり、第３実施形態の連続壁２Ｂを、水平方向に切断した断面図である。この図に示すように、第３実施形態では、連続壁２Ｂの上流側端部２２Ｂを、上流側に向かう程に幅を狭めて平面視略三角形状にしている。言い換えれば、上流側端部２２Ｂは、流動方向の下流側に向かって末広がりとなるように設けられている。このように構成することで、側方流動する土砂が上流側端部２２Ｂに到達すると、この土砂は、先尖状の端部によって容易に分流して、下流側に流れる。その結果、第３実施形態の地中連続壁基礎１でも、連続壁２Ｂに作用する流動圧が軽減され、地盤の側方流動の影響を受け難くすることができる。   FIG. 8 is a diagram for explaining a main part of the third embodiment, and is a cross-sectional view of the continuous wall 2B of the third embodiment cut in the horizontal direction. As shown in this figure, in the third embodiment, the upstream end 22B of the continuous wall 2B is formed in a substantially triangular shape in plan view with a width narrowing toward the upstream side. In other words, the upstream end 22B is provided so as to expand toward the downstream side in the flow direction. By comprising in this way, when the earth and sand which flow to the side reach | attain the upstream edge part 22B, this earth and sand will be easily shunted by the pointed end part, and will flow downstream. As a result, even in the underground continuous wall foundation 1 of the third embodiment, the flow pressure acting on the continuous wall 2B is reduced, and the influence of the lateral flow of the ground can be made difficult.

次に、第３実施形態の地中連続壁基礎１の構築について説明する。第３実施形態の地中連続壁基礎１の構築手順は、基本的に前述の第１実施形態で説明した構築手順と同様である。第１実施形態における構築手順との相違は、主に、鉄筋籠２４に設けられる端部形成用の型枠２６にある。図９に示すように、第３実施形態で用いる鉄筋籠２４において、側方流動方向の上流側の端部には、型枠２６が取り付けられている。この型枠２６は、上流側に向けて山状に折り曲げられた鉄板であり、鉄筋籠２４における高さ方向の全体に亘って設けられる。この型枠２６は、例えば溶接によって鉄筋籠２４に接合される。そして、型枠２６で区画された内側の空間、すなわち掘削溝Ｈ２における型枠２６よりも鉄筋籠２４側の空間にコンクリート２５を打設することで、連続壁２の上流側端部２２Ｂを型枠２６に倣った所望の形状に形成できる。   Next, construction of the underground continuous wall foundation 1 of the third embodiment will be described. The construction procedure of the underground continuous wall foundation 1 of the third embodiment is basically the same as the construction procedure described in the first embodiment. The difference from the construction procedure in the first embodiment is mainly in the end portion forming frame 26 provided in the reinforcing bar rod 24. As shown in FIG. 9, in the reinforcing bar rod 24 used in the third embodiment, a formwork 26 is attached to an upstream end portion in the lateral flow direction. The mold 26 is an iron plate bent in a mountain shape toward the upstream side, and is provided over the entire height direction of the reinforcing bar 24. This formwork 26 is joined to the reinforcing bar 24 by welding, for example. Then, by placing concrete 25 in an inner space defined by the mold 26, that is, in a space closer to the reinforcing bar 24 than the mold 26 in the excavation groove H2, the upstream end 22B of the continuous wall 2 is molded. It can be formed in a desired shape following the frame 26.

コンクリート２５の打設時には、コンクリート２５の重みによって型枠２６が過度に変形しないようにする必要がある。このような事情に鑑み、第３実施形態では、図１０（ａ），（ｂ）に示すように、型枠２６と掘削溝Ｈ２の隙間に砕石４４を詰めながらコンクリート２５を打設する。このようにすることで、型枠２６の過度な変形が抑えられ、連続壁２の上流側端部２２Ｂを所望の形状に作製できる。   When the concrete 25 is placed, it is necessary to prevent the formwork 26 from being excessively deformed by the weight of the concrete 25. In view of such circumstances, in the third embodiment, as shown in FIGS. 10A and 10B, the concrete 25 is placed while filling the crushed stone 44 in the gap between the mold 26 and the excavation groove H2. By doing in this way, the excessive deformation | transformation of the formwork 26 is suppressed and the upstream edge part 22B of the continuous wall 2 can be produced in a desired shape.

−−−第４実施形態−−−
図１１は、第４実施形態の要部を説明する図であり、連続壁２Ｃの外観斜視図である。この図に示すように、第４実施形態では、連続壁２Ｃにおける上流側端部の上半部分２２ＣＵを、第２実施形態の連続壁２Ａと同様に平面視で半円形状とし、下半部分２２ＣＬを断面積の欠損がない矩形状としている。このように構成することで、土砂の側方流動が比較的生じやすい地表側部分については、連続壁２Ｃに作用する流動圧を緩和でき、側方流動が比較的生じ難い地中側については連続壁２Ｃの支持力を確保できる。なお、図１１の例では、連続壁２Ｃの上流側端部における高さ方向の中間から上下に分けて上半部分２２ＣＵと下半部分２２ＣＬとしたが、境界の高さは任意に設定できる。 --- Fourth Embodiment ---
FIG. 11 is a diagram for explaining a main part of the fourth embodiment, and is an external perspective view of the continuous wall 2C. As shown in this figure, in the fourth embodiment, the upper half portion 22CU of the upstream end of the continuous wall 2C has a semicircular shape in plan view, like the continuous wall 2A of the second embodiment, and the lower half portion 22CL has a rectangular shape with no missing cross-sectional area. With such a configuration, the surface pressure on the surface side where the lateral flow of earth and sand is relatively likely to occur can be reduced, and the underground side where the lateral flow is relatively unlikely to occur can be relieved. The supporting force of the wall 2C can be ensured. In the example of FIG. 11, the upper half portion 22CU and the lower half portion 22CL are divided into the upper half portion 22CU and the lower half portion 22CL from the middle in the height direction at the upstream end portion of the continuous wall 2C, but the boundary height can be arbitrarily set.

次に、第４実施形態の地中連続壁基礎１の構築について説明する。第４実施形態の地中連続壁基礎１の構築手順は、基本的に前述の第３実施形態で説明した構築手順と同様である。例えば図１２に示すように、半円形状とする部分について型枠２７を作製し、鉄筋籠２４に接合する。なお、型枠２７の下端には底板２７ａを設けてあり、砕石４４の落下を抑制している。そして、図１３（ａ），（ｂ）に示すように、型枠２７における底板２７ａの高さまでコンクリート２５を打設したならば、型枠２７と掘削溝Ｈ２の隙間に砕石４４を詰める。そして、砕石４４の詰め込みとコンクリート２５の打設とを順次行い、最上部までコンクリート２５を打設する。このようにすることで、上半部分２２ＣＵを選択的に所望形状にできる。   Next, construction of the underground continuous wall foundation 1 of the fourth embodiment will be described. The construction procedure of the underground continuous wall foundation 1 of the fourth embodiment is basically the same as the construction procedure described in the third embodiment. For example, as shown in FIG. 12, a mold frame 27 is prepared for a semicircular portion and joined to a reinforcing bar 24. Note that a bottom plate 27 a is provided at the lower end of the mold 27 to suppress the falling of the crushed stone 44. Then, as shown in FIGS. 13A and 13B, when the concrete 25 is placed up to the height of the bottom plate 27a in the mold 27, the crushed stone 44 is packed in the gap between the mold 27 and the excavation groove H2. Then, the crushed stone 44 and the concrete 25 are placed in order, and the concrete 25 is placed to the top. By doing in this way, upper half part 22CU can be made into a desired shape selectively.

−−−変形例−−−
ところで、本発明は上述の実施形態に限定されるものではなく、種々の変形が可能である。 ---- Modified example ---
By the way, this invention is not limited to the above-mentioned embodiment, A various deformation | transformation is possible.

例えば、各実施形態では、複数の連続壁２を有する平行複壁式の地中連続壁基礎１を例示したが、連続壁２が１枚の地中連続壁基礎であってもよい。   For example, in each embodiment, although the parallel double-walled underground continuous wall foundation 1 which has the some continuous wall 2 was illustrated, the continuous wall 2 may be one underground continuous wall foundation.

また、構造物本体３に関し、フーチング３２がない形状の場合もある。この場合には、構造物本体３の最下端部が、各連続壁２の上面２３における長手方向中央付近に直接連結される形で構造が形成される。   The structure body 3 may have a shape without the footing 32. In this case, the structure is formed in such a manner that the lowermost end portion of the structure body 3 is directly connected to the vicinity of the center in the longitudinal direction on the upper surface 23 of each continuous wall 2.

第４実施形態のように、上半部分２２ＣＵを狭幅にするに際し、型枠２７を使用する以外の方法を採ってもよい。例えば、上半部分２２ＣＵに対応する部分をバケット４３で掘削してもよい。   As in the fourth embodiment, when narrowing the upper half portion 22CU, a method other than using the mold 27 may be employed. For example, a portion corresponding to the upper half portion 22CU may be excavated with the bucket 43.

また、第２実施形態のように、連続壁２Ａの上流側端部２２Ａを曲面で構成する場合、連続壁２Ａの高さに応じて曲面の曲率を定めてもよい。例えば、地表に近い程に楕円の度合いを強くし、地中深くなる程に矩形状に近付けるようにしてもよい。   Further, when the upstream end 22A of the continuous wall 2A is configured by a curved surface as in the second embodiment, the curvature of the curved surface may be determined according to the height of the continuous wall 2A. For example, the degree of ellipse may be strengthened as it is closer to the ground surface, and it may be closer to a rectangular shape as it is deeper in the ground.

１ 地中連続壁基礎
２，２Ａ，２Ｂ，２Ｃ 連続壁
２１ 壁面
２２ 端面
２２Ａ，２２Ｂ，２２Ｃ 上流側端部
２３ 上面
２４ 鉄筋籠
２５ コンクリート
２６ 型枠
３ 構造物本体
３１ 壁状部分
３２ フーチング
４１ 回転式掘削機
４２ トレミー管
４３ バケット
４４ 砕石 DESCRIPTION OF SYMBOLS 1 Underground continuous wall foundation 2, 2A, 2B, 2C Continuous wall 21 Wall surface 22 End surface 22A, 22B, 22C Upstream side end part 23 Upper surface 24 Reinforcement rod 25 Concrete 26 Formwork 3 Structure main body 31 Wall-shaped part 32 Footing 41 Rotation Excavator 42 Tremy tube 43 Bucket 44 Crushed stone

Claims (3)

基礎を構成する地中連続壁を、その壁面が土砂の側方流動方向に対して略平行となる向きに設けた地中連続壁基礎であって、
前記地中連続壁における前記側方流動方向の上流側端部は、前記壁体の上側部分にて上流側へ向かう程に狭幅となっており、下側部分にて矩形状となっていることを特徴とする地中連続壁基礎。 An underground continuous wall foundation comprising the underground continuous wall constituting the foundation in a direction in which the wall surface is substantially parallel to the lateral flow direction of the earth and sand,
The upstream end portion in the lateral flow direction of the underground continuous wall is narrower toward the upstream side in the upper portion of the wall body, and is rectangular in the lower portion. Underground continuous wall foundation characterized by that. 請求項１に記載の地中連続壁基礎を構築する構築方法であって、
地中に掘削溝を形成し、この掘削溝に鉄筋籠を建て込み、側方流動方向の上流側に位置する前記鉄筋籠の端部に、上流側へ向かう程に狭幅となる型枠を設け、前記掘削溝にコンクリートを打設することを特徴とする地中連続壁基礎の構築方法。 A construction method for constructing the underground continuous wall foundation according to claim 1 ,
A excavation groove is formed in the ground, a reinforcing bar is built in the excavation groove, and a formwork that becomes narrower toward the upstream side is formed at the end of the reinforcing bar located on the upstream side in the lateral flow direction. An underground continuous wall foundation construction method comprising providing concrete in the excavation groove. 基礎を構成する地中連続壁を、その壁面が土砂の側方流動方向に対して略平行となる向きに設けられ、前記地中連続壁における前記側方流動方向の上流側端部が、上流側へ向かう程に狭幅となっている地中連続壁基礎の構築方法であって、The underground continuous wall constituting the foundation is provided in such a direction that the wall surface is substantially parallel to the lateral flow direction of earth and sand, and the upstream end portion of the underground continuous wall in the lateral flow direction is upstream. It is a construction method of underground underground wall foundation that is narrower toward the side,
地中に掘削溝を形成し、この掘削溝に鉄筋籠を建て込み、側方流動方向の上流側に位置する前記鉄筋籠の端部に、上流側へ向かう程に狭幅となる型枠を設け、前記掘削溝にコンクリートを打設することを特徴とする地中連続壁基礎の構築方法。A excavation groove is formed in the ground, a reinforcing bar is built in the excavation groove, and a formwork that becomes narrower toward the upstream side is formed at the end of the reinforcing bar located on the upstream side in the lateral flow direction. An underground continuous wall foundation construction method comprising providing concrete in the excavation groove.
JP2009180997A 2009-08-03 2009-08-03 Underground continuous wall foundation made difficult to be affected by lateral flow of the ground, and its construction method Expired - Fee Related JP5407644B2 (en)

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JPS58189424A (en) * 1982-04-28 1983-11-05 Kajima Corp Method and apparatus for excavation for continuous wall of expansion of hole diameter for pile
JPH07113214B2 (en) * 1992-04-01 1995-12-06 トーメン建機株式会社 Excavation device for underground wall and construction method using the device
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