JP2006214201A - Composite foundation of piles and continuous underground wall - Google Patents

Composite foundation of piles and continuous underground wall Download PDF

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JP2006214201A
JP2006214201A JP2005029181A JP2005029181A JP2006214201A JP 2006214201 A JP2006214201 A JP 2006214201A JP 2005029181 A JP2005029181 A JP 2005029181A JP 2005029181 A JP2005029181 A JP 2005029181A JP 2006214201 A JP2006214201 A JP 2006214201A
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underground wall
continuous underground
pile
ground
intermediate layer
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Osamu Chiba
脩 千葉
Noriaki Isemoto
昇昭 伊勢本
Yoshitoshi Yasui
美敏 保井
Osamu Kaneko
治 金子
Takashi Nagareda
隆 流田
Takeshi Azumaguchi
剛 東口
Yoshio Takeuchi
義夫 武内
Keiichi Miyazaki
啓一 宮崎
Toshiyuki Hagiwara
敏行 萩原
Shinichiro Imamura
眞一郎 今村
Toshiaki Arai
寿昭 新井
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Nishimatsu Construction Co Ltd
Toda Corp
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Nishimatsu Construction Co Ltd
Toda Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite foundation of piles and a continuous underground wall, which efficiently and sufficiently bears axial-force load of a building built on soft ground, according to the ground structure, damps responsive displacement at the time of an earthquake to improve the habitability of the building, brings about upper skeleton reduction and change in structural type by virtue of reduction of input to a superstructure, achieves reduction of a pile cross sectional area and countermeasures against liquefaction, and contributes to total cost reduction and shortening of a construction period even if the continuous underground wall is employed. <P>SOLUTION: The soft ground 12 includes an intermediate layer 32 which is lower in rigidity than bearing ground 22 but higher than an upper layer 30. The continuous underground wall 18 is constructed so as to reach the depth of the intermediate layer 32, and the plurality of piles 16 reach the depth of the bearing ground 22. Then piles 16a at outermost locations out of all the piles 16 are arranged so as to correspond to the location of the continuous underground wall 18, united with the continuous underground wall 18, and each have a diameter larger than the thickness of the continuous underground wall 18. Therefore the piles 16 bear the axial-force load of the building 10, and the continuous underground wall 18 mainly bears only horizontal load at the time of an earthquake. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、杭と連続地中壁の複合基礎に関し、特に、軟弱地盤における杭と連続地中壁の複合基礎に関する。   The present invention relates to a composite foundation of a pile and a continuous underground wall, and particularly to a composite foundation of a pile and a continuous underground wall in soft ground.

一般に、建物の軸力を受けるため基礎杭が用いられている。   Generally, foundation piles are used to receive the axial force of buildings.

軟弱地盤では、地震時の水平荷重が加わったときの対処として、杭頭部を天端から杭径の5倍程度に相当する長さ分杭径を太くしたり鋼管を巻くなどの補強をするようにしている。   In soft ground, as a countermeasure when a horizontal load is applied in the event of an earthquake, the pile head is reinforced by increasing the pile diameter by a length equivalent to about 5 times the pile diameter from the top or winding a steel pipe. I am doing so.

しかし、軟弱地盤が厚く堆積するような場所に高層建物を建築するような場合、杭頭部を太くしただけでは建物の応答変位値が大きくなるため、杭基礎を連続地中壁杭にて囲うことが行われる場合がある。   However, when building a high-rise building in a place where soft ground accumulates thickly, the response displacement value of the building increases only by increasing the pile head, so the pile foundation is surrounded by continuous underground wall piles. Things may be done.

このように、連続地中壁を連続地中壁杭として使用する場合には、軸力荷重により連続地中壁杭の厚さが決まってしまい、厚い連続地中壁杭を支持地盤まで長く作らなければならず、掘削量やコンクリートの量が増え、非常に不経済で、工期も長くなり、掘削土量が増大し、建設残土が増大してしまうこととなる。   Thus, when using a continuous underground wall as a continuous underground wall pile, the thickness of the continuous underground wall pile is determined by the axial force load, and the thick continuous underground wall pile is made long to the support ground. The amount of excavation and concrete must be increased, which is very uneconomical, the construction period is lengthened, the amount of excavated soil is increased, and the construction soil is increased.

また、支持地盤までが深いと、厚い連続地中壁杭を深く、精度よく構築することが困難となる。   In addition, if the supporting ground is deep, it is difficult to construct a thick continuous underground wall pile deeply and accurately.

そのため、連続地中壁を支持地盤より浅く根入れさせ、この連続地中壁に一体化した杭を支持地盤にまで根入れすることで建物を補強する技術が提案されている(特許文献1参照)。
特開2001−226987号公報
Therefore, the technique which reinforces a building by making a continuous underground wall shallower than a support ground and making a pile integrated with this continuous underground wall into a support ground is proposed (refer to patent documents 1). ).
JP 2001-226987 A

このような特許文献1に記載される技術によれば、連続地中壁を短くできる点において、経済的で、工期の短縮化も図ることが可能である。   According to the technique described in Patent Document 1, it is economical in that the continuous underground wall can be shortened, and the construction period can be shortened.

しかし、特許文献1の技術では、連続地中壁の厚さと杭径の関係が明記されていないため連続地中壁に過度の負担が生じない工夫も必要である。   However, in the technique of Patent Document 1, since the relationship between the thickness of the continuous underground wall and the pile diameter is not specified, a device that does not cause an excessive burden on the continuous underground wall is required.

たとえば、建物の鉛直荷重を支持するために杭径を大きくしなければならないような場合、連続地中壁は地震時の水平荷重のみを負担するだけでよいにもかかわらず、連続地中壁の厚さも厚くしなければならない場合も多い。   For example, if the pile diameter must be increased to support the vertical load of the building, the continuous underground wall only has to bear the horizontal load during an earthquake, but the continuous underground wall Often the thickness must also be increased.

したがって、掘削量が多く、コンクリートの使用量も多くなって、掘削残土も増え、経済性もさほどは高くは望みにくい場合もある。   Therefore, the amount of excavation is large, the amount of concrete used is also increased, the amount of excavated soil is increased, and the economy is not so high, which may be difficult to expect.

また、同技術では、軟弱地盤の地盤構成を考慮していないため、地盤構成に応じた効率的な基礎構造が得られないものであった。   Further, in this technology, since the ground configuration of soft ground is not taken into consideration, an efficient foundation structure corresponding to the ground configuration cannot be obtained.

本発明の目的は、軟弱地盤において地盤構成を考慮に入れ、その地盤構成に応じて効率よく、建物の軸力荷重を十分に支持でき、地震時の応答変位を低減して居住性を向上させ、上部構造への入力低減による上部躯体の低減、また、構造種別の変更を可能とするとともに、杭断面低減及び液状化対策も可能として、連続地中壁を用いてもトータルなコスト低減、工期短縮が可能な杭と連続地中壁の複合基礎を提供することにある。   The object of the present invention is to consider the ground configuration in soft ground, efficiently support the building's axial load efficiently according to the ground configuration, reduce the response displacement during an earthquake and improve the comfortability. In addition, it is possible to reduce the upper frame by reducing the input to the superstructure, change the structure type, reduce the cross section of the pile and take measures against liquefaction. The purpose is to provide a composite foundation of piles and continuous underground walls that can be shortened.

前記目的を達成するため、本発明の杭と連続地中壁の複合基礎は、
(1)支持地盤まで到達して設けられる複数本の杭と、前記杭と一体に設けられる連続地中壁とを有し、軟弱地盤が前記支持地盤上に30m以上堆積した場所に構築される杭と連続地中壁の複合基礎であって、
前記軟弱地盤は、前記支持地盤よりは剛性が低くその上層よりは剛性の高い中間層を含み、
前記連続地中壁は、前記中間層までの深さに形成され、
前記杭は、最外周位置の杭が前記連続地中壁と同じ位置に配設されて連続地中壁と一体化され、
前記最外周位置の杭は、前記連続地中壁の厚さよりも大きな杭径とされ、
前記杭に建物の軸力荷重を負担させ、
前記連続地中壁には、主として地震時の水平荷重のみを負担させることを特徴とする。
To achieve the above object, the composite foundation of the pile and continuous underground wall of the present invention is
(1) It has a plurality of piles provided to reach the supporting ground, and a continuous underground wall provided integrally with the pile, and is constructed in a place where the soft ground is accumulated 30 m or more on the supporting ground. A composite foundation of piles and continuous underground walls,
The soft ground includes an intermediate layer that is lower in rigidity than the support ground and higher in rigidity than the upper layer,
The continuous underground wall is formed to a depth to the intermediate layer,
The pile is integrated with the continuous underground wall with the outermost pile located at the same position as the continuous underground wall,
The pile at the outermost peripheral position is a pile diameter larger than the thickness of the continuous underground wall,
Let the pile bear the axial load of the building,
The continuous underground wall mainly bears only a horizontal load during an earthquake.

本発明によれば、軟弱地盤では地盤の剛性が小さいため揺れやすく、居住性が悪く、この時の基礎への入力や変位が大きいと基礎部材に損傷を生じる可能性もあるが、軟弱地盤部分の連続地中壁を支持地盤よりは剛性が低くその上層よりは剛性の高い中間層まで形成し軟弱部分での基礎剛性を大きくすることにより、基礎の耐震性及び建物への入力低減を達成でき、連続地中壁を支持地盤まで形成する場合に比し、経済的で効率的な水平荷重処理を行うことが可能となる。   According to the present invention, in the soft ground, since the rigidity of the ground is small, it is easy to shake, the habitability is poor, and if the input and displacement to the foundation at this time are large, the foundation member may be damaged, but the soft ground part By forming the continuous underground wall of the base layer to a middle layer that is lower in rigidity than the supporting ground and higher in rigidity than the upper layer and increases the foundation rigidity in the soft part, it is possible to achieve earthquake resistance of the foundation and reduced input to the building Compared with the case where the continuous underground wall is formed up to the supporting ground, it is possible to perform an economical and efficient horizontal load treatment.

また、この連続地中壁と一体に杭を支持地盤まで形成することで、建物の鉛直荷重を確実に支持することができ、しかも、この杭を連続地中壁の厚さよりも大きな杭径とすることで、より大きな鉛直荷重を支持することができ、それだけ連続地中壁の厚さを薄くしてコスト削減歩及び工期の短縮化を達成することができる。   Also, by forming the pile up to the supporting ground integrally with this continuous underground wall, it is possible to reliably support the vertical load of the building, and this pile has a pile diameter larger than the thickness of the continuous underground wall. By doing so, a larger vertical load can be supported, and the thickness of the continuous underground wall can be reduced by that much, and cost reduction steps and shortening of the construction period can be achieved.

(2)本発明においては、(1)において、
前記中間層は、地表より所定の深さで前記支持地盤まで達する層厚を有することを特徴とする。
(2) In the present invention, in (1),
The intermediate layer has a layer thickness that reaches the support ground at a predetermined depth from the ground surface.

このような構成とすることにより、剛性の高い中間層を有効に利用して、より経済的で効率的な水平荷重処理を行うことが可能となる。   By adopting such a configuration, it is possible to perform a more economical and efficient horizontal load process by effectively using a rigid intermediate layer.

(3)本発明においては、(2)において、
前記最外周位置の杭は、上端が連続地中壁の上端位置まで延びていることを特徴とする。
(3) In the present invention, in (2),
The pile at the outermost peripheral position is characterized in that the upper end extends to the upper end position of the continuous underground wall.

このような構成とすることにより、中間層が十分な剛性を有する場合に、杭の上端を連続地中壁上端までのばすことで、杭に鉛直荷重を支持させ、連続地中壁に過大な鉛直荷重支持力がかかるのを防止することができる。   By adopting such a configuration, when the intermediate layer has sufficient rigidity, by extending the top end of the pile to the top end of the continuous underground wall, the pile is supported by the vertical load, and the continuous underground wall is excessively vertical. It is possible to prevent the load supporting force from being applied.

(4)本発明においては、(2)において、
前記最外周位置の杭は、上端が連続地中壁の途中位置まで延びていることを特徴とする。
(4) In the present invention, in (2),
The pile at the outermost peripheral position is characterized in that the upper end extends to a middle position of the continuous underground wall.

このような構成とすることにより、(3)の場合より中間層の剛性が小さい場合に、杭上端を連続地中壁の途中位置までとして、杭長さを短くすることができる。   By setting it as such a structure, when the rigidity of an intermediate | middle layer is smaller than the case of (3), a pile upper end can be made into the middle position of a continuous underground wall, and pile length can be shortened.

(5)本発明においては、(2)において、
前記最外周位置の杭は、上端が連続地中壁の下端位置で連続地中壁と連結されていることを特徴とする。
(5) In the present invention, in (2),
The pile at the outermost peripheral position is characterized in that the upper end is connected to the continuous underground wall at the lower end position of the continuous underground wall.

このような構成とすることにより、(4)の場合より中間層の剛性が小さい場合に、杭上端を連続地中壁の下端位置までとして、杭長さをより短くすることができる。   By setting it as such a structure, when the rigidity of an intermediate | middle layer is smaller than the case of (4), a pile length can be shortened by setting a pile upper end to the lower end position of a continuous underground wall.

(6)本発明においては、(1)において、
前記中間層は、地表より所定の深さで前記支持地盤まで達しない層厚を有し、
前記連続地中壁は、コーナー部のみ前記支持地盤まで達する深さに形成し、他の部分は前記中間層までの深さに形成され、
前記最外周位置の杭は、前記連続地中壁のコーナー部を除いて設けられることを特徴とする。
(6) In the present invention, in (1),
The intermediate layer has a layer thickness that does not reach the support ground at a predetermined depth from the ground surface,
The continuous underground wall is formed to a depth that reaches only the corner of the support ground, and the other part is formed to a depth to the intermediate layer,
The pile at the outermost peripheral position is provided except for a corner portion of the continuous underground wall.

このような構成とすることにより、中間層が地表より所定の深さで前記支持地盤まで達しない層厚である場合であっても、連続地中壁のコーナー部を支持地盤まで延長させることにより、コーナー部での高い剛性により水平荷重に対する剛性を大きくし、かつ、鉛直荷重を支持することができ、連続地中壁に囲まれた杭は軸力のみ負担させるので、杭の太さを細くして、コストを削減することが可能となる。   By adopting such a configuration, even when the intermediate layer has a layer thickness that does not reach the support ground at a predetermined depth from the ground surface, the corner portion of the continuous underground wall is extended to the support ground. , The rigidity against horizontal load is increased by the high rigidity at the corner, and the vertical load can be supported, and the pile surrounded by the continuous underground wall only bears the axial force, so the thickness of the pile is reduced Thus, the cost can be reduced.

(7)本発明においては、(1)〜(6)のいずれかにおいて、
前記中間層は、N値10以上の粘性土またはN値20以上の砂質土で、剪断波速度が250m/s以上の地盤であることを特徴とする。
(7) In the present invention, in any one of (1) to (6),
The intermediate layer is a clay soil having an N value of 10 or more or sandy soil having an N value of 20 or more, and is a ground having a shear wave velocity of 250 m / s or more.

このような構成とすることにより、中間層によって連続地中壁の水平変位を小さくできるとともにある程度の軸力荷重を負担できることとなる。   By setting it as such a structure, a horizontal displacement of a continuous underground wall can be made small by an intermediate | middle layer, and a certain amount of axial load can be borne.

(8)本発明においては、(1)〜(7)のいずれかにおいて、
前記中間層までの深さは、10m以上であることを特徴とする。
(8) In the present invention, in any one of (1) to (7),
The depth to the intermediate layer is 10 m or more.

このような構成とすることにより、連続地中壁を所定の深さに形成して、水平力の十分な負担をすることが可能となる。   By adopting such a configuration, it is possible to form a continuous underground wall at a predetermined depth and to apply a sufficient load of horizontal force.

(9)本発明においては、(1)〜(8)のいずれかにおいて、
前記中間層の層厚は、5m以上であることを特徴とする。
(9) In the present invention, in any one of (1) to (8),
The intermediate layer has a thickness of 5 m or more.

このような構成とすることにより、中間層によって連続地中壁の水平変位を小さくできるとともにある程度の軸力荷重を支持することが可能となる。   With such a configuration, the horizontal displacement of the continuous underground wall can be reduced by the intermediate layer, and a certain axial force load can be supported.

(10)本発明においては、(1)〜(9)のいずれかにおいて、
前記中間層に前記連続地中壁の下端を根入れしたことを特徴とする。
(10) In the present invention, in any one of (1) to (9),
A lower end of the continuous underground wall is embedded in the intermediate layer.

このような構成とすることにより、連続地中壁の下部を剛性の高い中間層に拘束させることができ、確実に水平荷重を負担することが可能となる。   By setting it as such a structure, the lower part of a continuous underground wall can be restrained to a rigid intermediate | middle layer, and it becomes possible to bear a horizontal load reliably.

以下、本発明の実施の形態について、図面を参照して説明する。   Embodiments of the present invention will be described below with reference to the drawings.

図1〜図6は、本発明の一実施の形態にかかる杭と連続地中壁の複合基礎を示す図である。   1-6 is a figure which shows the composite foundation of the pile concerning one embodiment of this invention, and a continuous underground wall.

図1は、この実施の形態にかかる杭と連続地中壁の複合基礎上に建物を構築した状態を示す断面図で、図2は、図1における複合基礎の横断面図である。   FIG. 1 is a cross-sectional view showing a state in which a building is constructed on a composite foundation of piles and continuous underground walls according to this embodiment, and FIG. 2 is a cross-sectional view of the composite foundation in FIG.

この実施の形態では、支持地盤22から30m以上軟弱地盤12が堆積した状態となっており、この軟弱地盤12には、支持地盤22よりは剛性が低くその上層30よりは剛性の高い中間層32が存在している。   In this embodiment, the soft ground 12 is accumulated 30 m or more from the support ground 22, and the soft ground 12 has an intermediate layer 32 that is lower in rigidity than the support ground 22 and higher in rigidity than the upper layer 30. Is present.

この中間層32は、図5に示すような性質で、地表面12aより所定の深さ、例えば10m以上で、支持地盤22まで達する層厚を有している。   The intermediate layer 32 has a property as shown in FIG. 5 and a layer thickness reaching the support ground 22 at a predetermined depth, for example, 10 m or more from the ground surface 12a.

この中間層32は、N値10以上の粘性土またはN値20以上の砂質土で、剪断波速度が250m/s以上の地盤である。   The intermediate layer 32 is a clay soil having an N value of 10 or more or sandy soil having an N value of 20 or more, and has a shear wave velocity of 250 m / s or more.

また、中間層32の層厚は5m以上となっている。   The layer thickness of the intermediate layer 32 is 5 m or more.

このような中間層32を有する軟弱地盤12における複合基礎14は、拡底杭である複数本の杭16を建物10の基礎底から支持地盤22まで到達して根入れさせるとともに、建物10の外周に沿って連続地中壁18を中間層32までの深さに形成している。   The composite foundation 14 in the soft ground 12 having such an intermediate layer 32 allows a plurality of piles 16 that are bottom-pile piles to reach the support ground 22 from the foundation bottom of the building 10 and to be embedded, and on the outer periphery of the building 10. A continuous underground wall 18 is formed along the intermediate layer 32 along the depth.

この連続地中壁18の下端は、中間層32の上部に根入れした状態となっている。   The lower end of the continuous underground wall 18 is in a state of being rooted in the upper part of the intermediate layer 32.

このように、連続地中壁18の下端を中間層32に支持させることで、連続地中壁18にある程度の軸力荷重を支持させると共に、建物10の下部を中間層32まで連続地中壁18によって囲い、かつ、中間層32で支持されているため、地震時の応答変位を低減して居住性を向上させることができる。   In this way, by supporting the lower end of the continuous underground wall 18 on the intermediate layer 32, a certain amount of axial load is supported on the continuous underground wall 18, and the lower part of the building 10 continues to the intermediate layer 32. Since it is enclosed by 18 and supported by the intermediate layer 32, the response displacement at the time of an earthquake can be reduced and the comfortability can be improved.

また、複数本の杭16は建物10の下部に所定間隔で配設され、そのうちの最外周の杭16aは、図2に示すように、連続地中壁18と同じ位置に配設されて連続地中壁18と一体化された状態となっている。   Further, the plurality of piles 16 are arranged at a predetermined interval in the lower part of the building 10, and the outermost piles 16a thereof are continuously arranged at the same position as the continuous underground wall 18 as shown in FIG. It is in a state integrated with the underground wall 18.

さらに、複数本の杭16は、全て同一径とされ、その径は、連続地中壁18の厚さtよりも大きな杭径dとされている。   Further, the plurality of piles 16 are all the same diameter, and the diameter is a pile diameter d larger than the thickness t of the continuous underground wall 18.

これは、連続地中壁18の厚さは、主として水平力を処理することから、一般に水平剛性が十分で鉛直荷重に耐える厚さとして120cm程度としているのに対して、杭16の径は荷重支持力の関係上それよりも大きくされることが多いからである。   This is because, since the thickness of the continuous underground wall 18 mainly handles horizontal force, the thickness of the pile 16 is generally about 120 cm as the thickness with sufficient horizontal rigidity and withstanding vertical load. This is because it is often made larger than that due to the bearing capacity.

この場合、最外周の杭16aのみを連続地中壁18の厚さtよりも大きな杭径dとし、他の内側の杭16bをそれよりも細い杭径として、コストを削減するようにしてもよい。   In this case, only the outermost pile 16a is set to a pile diameter d larger than the thickness t of the continuous underground wall 18, and the other inner pile 16b is set to a thinner pile diameter so as to reduce the cost. Good.

このように、連続地中壁18と一体に最外周の杭16aを形成することで、建物10の鉛直荷重を確実に支持することができ、しかも、少なくとも最外周の杭16aを連続地中壁の厚さtよりも大きな杭径dとすることで、より大きな鉛直荷重を支持することができ、それだけ連続地中壁18の厚さtを薄くしてコスト削減及び工期の短縮化を達成することができる。   Thus, by forming the outermost pile 16a integrally with the continuous underground wall 18, the vertical load of the building 10 can be reliably supported, and at least the outermost pile 16a is connected to the continuous underground wall. By making the pile diameter d larger than the thickness t, the larger vertical load can be supported, and the thickness t of the continuous underground wall 18 is reduced by that much, thereby achieving cost reduction and shortening the construction period. be able to.

また、図3に示すように、中間層32の剛性に応じて連続地中壁18に対する最外周の杭16aの飲み込み量を変えるようにしている。   Further, as shown in FIG. 3, the amount of swallowing of the outermost pile 16 a with respect to the continuous underground wall 18 is changed according to the rigidity of the intermediate layer 32.

例えば、同図(1)は、中間層32が十分な剛性を有する場合で、この場合、連続地中壁18に過大な支持力がかかる可能性があり、そのため、杭16aの上端を連続地中壁18の上端までのばすことで、杭16aに鉛直荷重を支持させ、連続地中壁18に過大な鉛直荷重支持力がかかるのを防止するようにしている。   For example, FIG. 1A shows a case where the intermediate layer 32 has sufficient rigidity. In this case, an excessive support force may be applied to the continuous underground wall 18, and therefore the upper end of the pile 16a is connected to the continuous ground. By extending to the upper end of the middle wall 18, the pile 16 a is supported with a vertical load, and an excessive vertical load supporting force is prevented from being applied to the continuous underground wall 18.

特に、連続地中壁18の厚さを薄くした場合には、連続地中壁18の鉛直方向の応力負担を軽減するために、この構造を採用することが肝要である。   In particular, when the thickness of the continuous underground wall 18 is reduced, it is important to adopt this structure in order to reduce the stress load in the vertical direction of the continuous underground wall 18.

この場合の施工は、先に連続地中壁1ユニット20を杭16aの径分間隔sをあけて施工しておき、後で間隔s位置に杭16aの施工を行うという通常の連続地中壁の施工手順で行うことができる。   The construction in this case is a normal continuous underground wall in which the continuous underground wall 1 unit 20 is first constructed with a gap s between the diameters of the piles 16a, and then the piles 16a are constructed at the intervals s. It can be done with the construction procedure.

さらに、杭16aの軸径が大きい場合、連続地中壁材料の軸方向の強度を考慮し、同図(4)、(5)のように連続地中壁18下端まで軸径d1で、下端から拡径し、軸荷重をささえる軸径d2とすることにより、経済的な設計とすることができる。   Furthermore, when the axial diameter of the pile 16a is large, the axial strength of the continuous underground wall material is taken into consideration, and the lower end of the continuous underground wall 18 has an axial diameter d1 as shown in FIGS. The shaft diameter d2 that increases the diameter of the shaft and reduces the shaft load can be economical.

また、同図(2)は、(1)の場合より中間層32の剛性が小さい場合で、この場合、連続地中壁18に係る荷重は前述の場合より小さくなるので、杭16aの上端を連続地中壁18の途中位置までとして、杭16aの長さを短くするようにしている。   FIG. 2B is a case where the rigidity of the intermediate layer 32 is smaller than in the case of FIG. 1B. In this case, the load applied to the continuous underground wall 18 is smaller than that in the above case. The length of the pile 16a is shortened to the middle position of the continuous underground wall 18.

この場合、杭16aを掘削機の拡頭等によって大きく形成することができる。   In this case, the pile 16a can be largely formed by expanding the head of the excavator.

さらに、同図(3)は、(2)の場合よりもさらに中間層32の剛性が小さい場合で、この場合、連続地中壁18に係る荷重は前述の場合より小さくなるので、杭16aの上端を連続地中壁18の下端位置までとして、杭16aの長さをより短くするようにしている。   Further, (3) in the figure is a case where the rigidity of the intermediate layer 32 is further smaller than in the case of (2). In this case, the load on the continuous underground wall 18 is smaller than that in the above case. The upper end is extended to the lower end position of the continuous underground wall 18, and the length of the pile 16a is made shorter.

この場合、連続地中壁18の拡底して大きくすることで杭16aを形成することができる。   In this case, the pile 16a can be formed by increasing the bottom of the continuous underground wall 18 and enlarging it.

次に、地震時の性質について図6に示す中間層について検討した結果を示す。   Next, the result of having examined the intermediate layer shown in FIG. 6 about the property at the time of an earthquake is shown.

地盤構成は、同図(1)に示すように、0〜20mでは剪断波速度120m/s、20m〜40mでは250m/s、40m〜50mでは300m/s、50m〜60mでは350m/s、60m以深は450m/s(支持地盤相当)となっている。   As shown in FIG. 1 (1), the ground structure is a shear wave velocity of 120 m / s at 0 to 20 m, 250 m / s at 20 m to 40 m, 300 m / s at 40 m to 50 m, 350 m / s at 60 m to 60 m, and 60 m. The depth is 450 m / s (equivalent to supporting ground).

ここでは、同図(2)に示すように、地震波を建築の設計検討でよく用いられる告示波と臨海波の2種類設定し、超高層建物をイメージし、1次固有周期0.27Hz(3.8秒)の1質点モデルにより動的応答計算を行った。   Here, as shown in Fig. 2 (2), two types of seismic waves, a notification wave and a coastal wave, which are often used in architectural design studies, are set up to image a high-rise building, and a primary natural period of 0.27 Hz (3 .8 seconds) dynamic response calculation was performed using a one-mass model.

基礎は、支持用の外周杭を設置し、中間層上までの20mまでを連続地中壁としたもの、杭のみの基礎の2種類を検討した。   For the foundation, two types of foundations were installed: one with an outer peripheral pile for support, up to 20 m up to the middle layer, and a foundation with only a pile.

耐震設計上重要となる、建物の最大応答加速度及び最大応答変位、基礎の最大応答加速度及び最大応答変位について比較検討したところ、20m連続地中壁にすることにより、連続地中壁を用いない杭基礎に対して、応答値によっては50%の軽減になっており、杭基礎よりもすべての項目で大いに優れている。   When we compared the maximum response acceleration and maximum response displacement of the building, the maximum response acceleration and maximum response displacement of the foundation, which are important for seismic design, a pile that does not use a continuous underground wall by making a 20m continuous underground wall It is reduced by 50% depending on the response value with respect to the foundation, which is much better in all items than the pile foundation.

図7には、本発明の他の実施の形態にかかる杭と連続地中壁の複合基礎を示す。   FIG. 7 shows a composite foundation of piles and continuous underground walls according to another embodiment of the present invention.

この実施の形態では、軟弱地盤12には、支持地盤22よりは剛性が低く、その上層30よりは剛性の高い中間層34が存在し、地表面12aより所定の深さ、例えば10m以上で、支持地盤22まで達しない層厚、例えば5m以上を有している。   In this embodiment, the soft ground 12 has an intermediate layer 34 that is lower in rigidity than the support ground 22 and higher in rigidity than the upper layer 30, and has a predetermined depth from the ground surface 12 a, for example, 10 m or more, It has a layer thickness that does not reach the supporting ground 22, for example, 5 m or more.

また、この中間層34は、N値10以上の粘性土またはN値20以上の砂質土で、剪断波速度が250m/s以上の地盤となっている。   The intermediate layer 34 is a clay soil having an N value of 10 or more or a sandy soil having an N value of 20 or more, and has a ground having a shear wave velocity of 250 m / s or more.

このような中間層34を有する軟弱地盤12に設けられる複合基礎14は、拡底杭である複数の杭16のうち内側の杭(図示せず)を建物10の基礎底から支持地盤22まで到達して根入れするとともに、連続地中壁18のコーナー部36のみ支持地盤22まで達する深さに形成し、他の部分、コーナー部36間の壁部38を中間層34までの深さに形成している。   The composite foundation 14 provided on the soft ground 12 having such an intermediate layer 34 reaches an inner pile (not shown) from the foundation bottom of the building 10 to the support ground 22 among the plurality of piles 16 that are bottom-up piles. In addition, only the corner portion 36 of the continuous underground wall 18 is formed to a depth reaching the support ground 22, and the wall portion 38 between the other portion and the corner portion 36 is formed to the depth to the intermediate layer 34. ing.

また、最外周位置の杭16aは、コーナー部36位置を除いて連続地中壁18と同じ位置に配設されて連続地中壁18と一体に設けられている。   Further, the pile 16a at the outermost peripheral position is disposed at the same position as the continuous underground wall 18 except for the corner portion 36, and is provided integrally with the continuous underground wall 18.

この連続地中壁18の壁部38の下端は、中間層34の上部に根入れした状態となっている。   The lower end of the wall portion 38 of the continuous underground wall 18 is in a state of being embedded in the upper portion of the intermediate layer 34.

このように、連続地中壁18をコーナー部36に支持地盤22まで達する深さに形成し、他の部分は中間層34までの深さに形成することで、中間層34の下側に軟弱な下層40が続く場合でも、連続地中壁18のコーナー部36を支持地盤22まで延長させることにより、コーナー部での水平荷重に対する十分な剛性を確保するとともに、コーナー外杭に代わり軸力荷重を支持することができ、コーナー外杭を省略できるとともに、内側の杭は軸力のみ負担させるので杭の太さを細くして、コストを削減することが可能となる。   In this way, the continuous underground wall 18 is formed to a depth reaching the support ground 22 at the corner portion 36, and the other portion is formed to a depth to the intermediate layer 34, so that the lower side of the intermediate layer 34 is soft. Even if the lower layer 40 continues, the corner portion 36 of the continuous underground wall 18 is extended to the supporting ground 22 to ensure sufficient rigidity against the horizontal load at the corner portion, and the axial load is substituted for the pile outside the corner. Can be omitted, and the pile outside the corner can be omitted, and since the inner pile bears only the axial force, it is possible to reduce the thickness of the pile and reduce the cost.

また、建物10の下部は中間層34まで連続地中壁18によって囲われ、かつ、連続地中壁18が中間層34によって支持されているため、地震時の応答変位を低減して居住性を向上させることができる。   In addition, the lower part of the building 10 is surrounded by the continuous underground wall 18 up to the intermediate layer 34, and the continuous underground wall 18 is supported by the intermediate layer 34. Can be improved.

他の構成及び作用は、前記実施の形態と同様につき説明を省略する。   Other configurations and operations are the same as those in the above embodiment, and a description thereof will be omitted.

本発明は、前記実施の形態に限定されるものではなく、本発明の要旨の範囲内において種々の形態に変形可能である。   The present invention is not limited to the above-described embodiment, and can be modified into various forms within the scope of the gist of the present invention.

前記実施の形態では、建物の高さが150mとされているが、この例に限定されるものではなく、建物の高さは任意に変更可能である。   In the said embodiment, although the height of a building is 150 m, it is not limited to this example, The height of a building can be changed arbitrarily.

本発明の一実施の形態に係る杭と連続地中壁の複合基礎上に建物を構築した状態を示す断面図である。It is sectional drawing which shows the state which built the building on the composite foundation of the pile which concerns on one embodiment of this invention, and a continuous underground wall. 図1における複合基礎の横断面図である。It is a cross-sectional view of the composite foundation in FIG. 中間層の剛性に応じた連続地中壁に対する杭の飲み込み量を示すもので、(1)は最も剛性が高い場合の断面図、(2)はそれよりも剛性が低い場合の断面図、(3)は最も剛性が低い場合の断面図、(4)は剛性が大きく杭径が大きい断面図、(5)は剛性が大きく杭径が大きい平断面図である。It shows the swallowing amount of the pile with respect to the continuous underground wall according to the rigidity of the intermediate layer, (1) is a sectional view when the rigidity is the highest, (2) is a sectional view when the rigidity is lower than that, ( 3) is a cross-sectional view when rigidity is the lowest, (4) is a cross-sectional view with high rigidity and a large pile diameter, and (5) is a flat cross-sectional view with high rigidity and a large pile diameter. 連続地中壁と杭の施工状態を示す説明図である。It is explanatory drawing which shows the construction state of a continuous underground wall and a pile. 図1の中間層の一例を示す図である。It is a figure which shows an example of the intermediate | middle layer of FIG. 図1の中間層を有する場合の地震時の応答計算結果を示すもので、(1)は対象とする地盤条件を示す図で、(2)は各部位の杭基礎との比を示す図である。It shows the response calculation result at the time of the earthquake when it has the intermediate layer of FIG. 1, (1) is a diagram showing the ground conditions to be targeted, (2) is a diagram showing the ratio of the pile foundation of each part is there. 本発明の他の実施の形態に係る杭と連続地中壁の複合基礎を示す断面図である。It is sectional drawing which shows the composite foundation of the pile which concerns on other embodiment of this invention, and a continuous underground wall.

符号の説明Explanation of symbols

10 建物
12a 地表面
14 複合基礎
16 杭
16a 最外周の杭
18 連続地中壁
22 支持地盤
30 上層
32、34 中間層
36 コーナー部
40 下層
DESCRIPTION OF SYMBOLS 10 Building 12a Ground surface 14 Composite foundation 16 Pile 16a Outermost pile 18 Continuous underground wall 22 Support ground 30 Upper layer 32, 34 Middle layer 36 Corner part 40 Lower layer

Claims (10)

支持地盤まで到達して設けられる複数本の杭と、前記杭と一体に設けられる連続地中壁とを有し、軟弱地盤が前記支持地盤上に30m以上堆積した場所に構築される杭と連続地中壁の複合基礎であって、
前記軟弱地盤は、前記支持地盤よりは剛性が低くその上層よりは剛性の高い中間層を含み、
前記連続地中壁は、前記中間層までの深さに形成され、
前記杭は、最外周位置の杭が前記連続地中壁と同じ位置に配設されて連続地中壁と一体化され、
前記最外周位置の杭は、前記連続地中壁の厚さよりも大きな杭径とされ、
前記杭に建物の軸力荷重を負担させ、
前記連続地中壁には、主として地震時の水平荷重のみを負担させることを特徴とする杭と連続地中壁の複合基礎。
It has a plurality of piles that are provided to reach the supporting ground, and a continuous underground wall that is provided integrally with the pile, and is continuous with a pile that is constructed in a place where the soft ground has accumulated 30 m or more on the supporting ground. A complex foundation of underground walls,
The soft ground includes an intermediate layer that is lower in rigidity than the support ground and higher in rigidity than the upper layer,
The continuous underground wall is formed to a depth to the intermediate layer,
The pile is integrated with the continuous underground wall with the outermost pile located at the same position as the continuous underground wall,
The pile at the outermost peripheral position is a pile diameter larger than the thickness of the continuous underground wall,
Let the pile bear the axial load of the building,
A composite foundation of a pile and a continuous underground wall, wherein the continuous underground wall mainly bears only a horizontal load during an earthquake.
請求項1において、
前記中間層は、地表より所定の深さで前記支持地盤まで達する層厚を有することを特徴とする杭と連続地中壁の複合基礎。
In claim 1,
The intermediate layer has a layer thickness that reaches the support ground at a predetermined depth from the ground surface, and is a composite foundation of a pile and a continuous underground wall.
請求項2において、
前記最外周位置の杭は、上端が連続地中壁の上端位置まで延びていることを特徴とする杭と連続地中壁の複合基礎。
In claim 2,
The pile at the outermost peripheral position has an upper end extending to an upper end position of a continuous underground wall.
請求項2において、
前記最外周位置の杭は、上端が連続地中壁の途中位置まで延びていることを特徴とする杭と連続地中壁の複合基礎。
In claim 2,
The pile of the outermost periphery position is a composite foundation of a pile and a continuous underground wall, wherein an upper end extends to a midway position of the continuous underground wall.
請求項2において、
前記最外周位置の杭は、上端が連続地中壁の下端位置で連続地中壁と連結されていることを特徴とする杭と連続地中壁の複合基礎。
In claim 2,
The pile at the outermost periphery position is connected to the continuous underground wall at the lower end position of the continuous underground wall, and the pile and continuous underground wall composite foundation.
請求項1において、
前記中間層は、地表より所定の深さで前記支持地盤まで達しない層厚を有し、
前記連続地中壁は、コーナー部のみ前記支持地盤まで達する深さに形成し、他の部分は前記中間層までの深さに形成され、
前記最外周位置の杭は、前記連続地中壁のコーナー部を除いて設けられることを特徴とする杭と連続地中壁の複合基礎。
In claim 1,
The intermediate layer has a layer thickness that does not reach the support ground at a predetermined depth from the ground surface,
The continuous underground wall is formed to a depth that reaches only the corner of the support ground, and the other part is formed to a depth to the intermediate layer,
The pile at the outermost peripheral position is provided except for a corner portion of the continuous underground wall, and is a composite foundation of a pile and a continuous underground wall.
請求項1〜6のいずれかにおいて、
前記中間層は、N値10以上の粘性土またはN値20以上の砂質土で、剪断波速度が250m/s以上の地盤であることを特徴とする杭と連続地中壁の複合基礎。
In any one of Claims 1-6,
The intermediate layer is a viscous foundation having an N value of 10 or more or a sandy soil having an N value of 20 or more, and is a ground having a shear wave velocity of 250 m / s or more.
請求項1〜7のいずれかにおいて、
前記中間層までの深さは、10m以上であることを特徴とする杭と連続地中壁との複合基礎。
In any one of Claims 1-7,
The composite foundation of a pile and a continuous underground wall, characterized in that the depth to the intermediate layer is 10 m or more.
請求項1〜8のいずれかにおいて、
前記中間層の層厚は、5m以上であることを特徴とする杭と連続地中壁との複合基礎。
In any one of Claims 1-8,
A composite foundation of a pile and a continuous underground wall, wherein the intermediate layer has a thickness of 5 m or more.
請求項1〜9のいずれかにおいて、
前記中間層に前記連続地中壁の下端を根入れしたことを特徴とする杭と連続地中壁との複合基礎。
In any one of Claims 1-9,
A composite foundation of a pile and a continuous underground wall, wherein a lower end of the continuous underground wall is embedded in the intermediate layer.
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CN100465390C (en) * 2006-12-07 2009-03-04 沈阳建筑大学 Composite building foundation based on waste steel slag
CN102359118A (en) * 2011-08-02 2012-02-22 北京健安诚岩土工程有限公司 Annular foundation of underground continuous wall and construction method thereof
CN102359118B (en) * 2011-08-02 2013-12-04 北京健安诚岩土工程有限公司 Annular foundation of underground continuous wall and construction method thereof
CN105756075A (en) * 2016-02-29 2016-07-13 山东电力工程咨询院有限公司 Horizontal bearing combined foundation based on piles and underground continuous wall and method

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