JP2019203347A - Support structure of earth retaining wall - Google Patents
Support structure of earth retaining wall Download PDFInfo
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- JP2019203347A JP2019203347A JP2018100428A JP2018100428A JP2019203347A JP 2019203347 A JP2019203347 A JP 2019203347A JP 2018100428 A JP2018100428 A JP 2018100428A JP 2018100428 A JP2018100428 A JP 2018100428A JP 2019203347 A JP2019203347 A JP 2019203347A
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- 238000009412 basement excavation Methods 0.000 claims abstract description 39
- 238000006073 displacement reaction Methods 0.000 abstract description 17
- 230000001629 suppression Effects 0.000 abstract description 10
- 239000004568 cement Substances 0.000 description 19
- 238000010276 construction Methods 0.000 description 14
- 239000002689 soil Substances 0.000 description 14
- 238000010586 diagram Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 239000008267 milk Substances 0.000 description 4
- 210000004080 milk Anatomy 0.000 description 4
- 235000013336 milk Nutrition 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000004873 anchoring Methods 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明は、掘削底面より下方地盤に控え壁状の地盤改良部が設けられる土留め壁の支持構造に関するものである。 The present invention relates to a retaining wall support structure in which a retaining wall-like ground improvement portion is provided on the ground below the bottom of excavation.
地下に構造物を構築したり、ボックスカルバートなどを埋設したりする際には、掘削面を保護する土留め壁を設けて地盤を掘り下げることが行われる。そして、建物や公共施設が密集する市街地においては、掘削によって周辺地盤が変形又は沈下するなどの影響を可能な限り抑えるために、様々な変位抑制対策が施される。 When constructing a structure underground or burying a box culvert, a ground retaining wall that protects the excavation surface is provided and the ground is dug down. And in an urban area where buildings and public facilities are densely packed, various displacement suppression measures are taken in order to suppress as much as possible the influence of deformation or subsidence of surrounding ground due to excavation.
例えば特許文献1には、土留め壁の内側に梁状のソイルストラッドを設けて、対向する山留め壁間を掘削底面下の地盤内で連結させる工法が開示されている。また、特許文献１，２には、山留め壁の根入れの掘削側の地盤に、一定の深度で同じ長さのソイルセメント柱列を設けることで控え壁（バットレス）を構築し、土留め壁の水平変位量を低減させることが記載されている。 For example, Patent Document 1 discloses a construction method in which a beam-shaped soil straddle is provided inside the earth retaining wall and the opposing mountain retaining walls are connected in the ground below the bottom of the excavation. In Patent Documents 1 and 2, a retaining wall (buttress) is constructed by providing a soil cement column of the same length at a certain depth on the ground on the excavation side of the retaining wall. It is described that the amount of horizontal displacement is reduced.
しかしながら一定の長さのソイルセメント柱列などの地盤改良部を設ける工法では、本来はあまり必要でない部分にまで地盤改良を行うことになり、工費や工期などに無駄が生じている可能性がある。 However, in the construction method in which a ground improvement part such as a soil cement column train of a certain length is provided, the ground improvement will be carried out to the part that is not so much necessary, and there is a possibility that the construction cost and construction period are wasted. .
そこで、本発明は、必要とされる変位抑止性能を確保したうえで、地盤改良の範囲を低減することが可能な土留め壁の支持構造を提供することを目的としている。 Therefore, an object of the present invention is to provide a retaining structure for a retaining wall capable of reducing the range of ground improvement while ensuring the required displacement restraining performance.
前記目的を達成するために、本発明の土留め壁の支持構造は、掘削底面より下方地盤に控え壁状の地盤改良部が設けられる土留め壁の支持構造であって、前記地盤改良部は、土留め壁の壁面に対して略直交する方向に延伸されるとともに、前記土留め壁に隣接して設けられる深度方向に長い長尺部と、前記長尺部の上部又は下部にのみ隣接して設けられる短尺部とを備えていることを特徴とする。 To achieve the above object, the retaining wall support structure of the present invention is a retaining wall support structure in which a retaining wall-shaped ground improvement portion is provided on the ground below the bottom of excavation, and the ground improvement portion is And extending in a direction substantially orthogonal to the wall surface of the retaining wall, and being adjacent to only the upper part or the lower part of the elongated part that is long in the depth direction provided adjacent to the retaining wall. And a short part provided.
ここで、前記地盤改良部は、前記土留め壁の幅方向に対して間隔を置いて複数設けられる構成とすることができる。また、前記地盤改良部は、柱状改良体を連続して設けることによって形成される構成とすることができる。 Here, a plurality of the ground improvement portions may be provided at intervals with respect to the width direction of the retaining wall. Moreover, the said ground improvement part can be set as the structure formed by providing a columnar improvement body continuously.
このように構成された本発明の土留め壁の支持構造では、土留め壁の壁面に対して略直交する方向に延伸される控え壁状の地盤改良部が、土留め壁に隣接して設けられる長尺部と、それに隣接して上部又は下部にのみ設けられる短尺部とによって構成される。 In the retaining wall support structure of the present invention thus configured, a retaining wall-shaped ground improvement portion extending in a direction substantially orthogonal to the wall surface of the retaining wall is provided adjacent to the retaining wall. And a short part provided only at an upper part or a lower part adjacent to the long part.
このため、控え壁状の地盤改良部によって土留め壁に必要とされる変位抑止性能が確保できるうえに、短尺部の上方又は下方は地盤改良を行わなくてもよくなるため、地盤改良の範囲を低減することができる。 For this reason, the retaining wall-shaped ground improvement part can ensure the displacement suppression performance required for the retaining wall, and the upper part or the lower part of the short part does not need to be improved. Can be reduced.
このような控え壁状の地盤改良部は、土留め壁の幅方向に対して間隔を置いて複数設けることができる。また、地盤に柱状改良体を連続して設けることで、地盤改良部とすることができる。 A plurality of such retaining wall-shaped ground improvement portions can be provided at intervals in the width direction of the retaining wall. Moreover, it can be set as a ground improvement part by providing a columnar improvement body in the ground continuously.
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。図１は、本実施の形態の土留め壁の支持構造の構成を説明する斜視図である。また、図２は、土留め壁を使用した掘削工事の各工程を説明する図である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view for explaining the structure of the retaining wall support structure of the present embodiment. Moreover, FIG. 2 is a figure explaining each process of excavation construction using a retaining wall.
土留め壁１は、地盤Ｇをそのまま掘削した際に現れる鉛直の掘削面を保護するために設けられる。ここで、土留め壁１の掘削側に露出する壁面は、ほぼ鉛直面となる。本実施の形態では、後述するように複数のソイルセメント柱１１，・・・を列状に並べることによって壁が形成される土留め壁１を例に説明する。 The retaining wall 1 is provided to protect a vertical excavation surface that appears when the ground G is excavated as it is. Here, the wall surface exposed to the excavation side of the earth retaining wall 1 is a substantially vertical surface. In the present embodiment, as will be described later, the earth retaining wall 1 in which a wall is formed by arranging a plurality of soil cement pillars 11 in a row will be described as an example.
なお、本実施の形態の土留め壁の支持構造は、上述した以外にも様々な形態の土留め壁に対して適用することができる。すなわち、鋼矢板、親杭横矢板、鋼管矢板、地下連続壁、泥水固化壁など、いずれの形態の土留め壁に対しても適用することができる。 The retaining wall support structure of the present embodiment can be applied to various forms of retaining walls other than those described above. That is, the present invention can be applied to any form of retaining wall such as a steel sheet pile, a main pile sheet pile, a steel pipe sheet pile, an underground continuous wall, and a muddy water solidified wall.
本実施の形態の土留め壁の支持構造は、土留め壁１の根入れ部分の掘削底面Ｓ側に設けられる。地盤Ｇを掘り下げたときの掘削空間の底となる掘削底面Ｓより深い部分が土留め壁１の根入れとなり、その根入れの水平方向の変位を抑えるために土留め壁の支持構造が設けられる。 The retaining wall support structure of the present embodiment is provided on the excavation bottom surface S side of the root portion of the retaining wall 1. A portion deeper than the excavation bottom surface S that becomes the bottom of the excavation space when the ground G is dug down becomes the anchorage of the retaining wall 1, and a retaining wall support structure is provided to suppress horizontal displacement of the anchoring. .
本実施の形態の土留め壁の支持構造となる地盤改良部２は、土留め壁１の控え壁状に設けられる。すなわち土留め壁１の下部となる根入れ部分を、掘削空間側から支える控え壁（バットレス）として設けられる。 The ground improvement part 2 which becomes the support structure of the retaining wall of the present embodiment is provided in the shape of a retaining wall of the retaining wall 1. In other words, the base portion that is the lower portion of the retaining wall 1 is provided as a retaining wall (buttress) that supports the excavation space side.
土留め壁１は、掘削によって掘削面側に作用する圧力が開放されると、不安定な状態になって傾きやすくなる。土留め壁１の代表的な変形パターンは、上記圧力の不均等性が要因となり、土留め壁１が掘削底面Ｓ側にはらみ出すことによって起きる。このため、土留め壁１の根入れの移動方向に控え壁状の地盤改良部２を設けておくことで、その抵抗によって土留め壁１の変位を抑制することができる。 When the pressure acting on the excavation surface side is released by excavation, the earth retaining wall 1 becomes unstable and easily tilts. A typical deformation pattern of the retaining wall 1 is caused by the retaining wall 1 protruding toward the excavation bottom surface S due to the non-uniformity of the pressure. For this reason, by providing the retaining wall-shaped ground improvement part 2 in the moving direction of the basement of the earth retaining wall 1, the displacement of the earth retaining wall 1 can be suppressed by its resistance.
鉛直方向に延伸される地盤改良部２は、土留め壁１の壁面に対して略直交する方向にも延伸される。このように、土留め壁１の変位方向に延伸される抵抗体を設けることで、変位抑止性能を充分に発揮させることができる。 The ground improvement portion 2 that extends in the vertical direction is also extended in a direction substantially perpendicular to the wall surface of the retaining wall 1. Thus, by providing the resistor extended in the displacement direction of the earth retaining wall 1, the displacement suppression performance can be sufficiently exhibited.
この地盤改良部２は、土留め壁１に隣接して設けられる深度方向に長い長尺部２１と、長尺部２１の一部にのみ隣接して設けられる短尺部２２とによって主に構成される。本実施の形態では、短尺部２２を長尺部２１の上部に隣接して設ける場合について説明する。 This ground improvement part 2 is mainly comprised by the elongate part 21 provided in the depth direction provided adjacent to the earth retaining wall 1, and the short part 22 provided adjacent only to a part of long part 21. As shown in FIG. The In the present embodiment, a case where the short portion 22 is provided adjacent to the upper portion of the long portion 21 will be described.
地盤改良部２は、地盤に例えばセメント系の固化材を混入しながら撹拌することによって構築される。例えば、オーガーや撹拌翼によって地盤を撹拌しながらセメントミルクを注入することで構築されるソイルセメント柱によって、地盤改良部２を設けることができる。また、固化材を高圧ジェット噴射させながら地盤と混合する噴射撹拌工法によっても地盤改良部２を設けることができる。 The ground improvement unit 2 is constructed by stirring the ground while mixing, for example, a cement-based solidifying material. For example, the ground improvement part 2 can be provided by a soil cement column constructed by injecting cement milk while stirring the ground with an auger or a stirring blade. Moreover, the ground improvement part 2 can be provided also by the jet stirring construction method which mixes with a ground, making a solidified material jet-jet.
ここで、ソイルセメント柱などの柱状改良体２１１，２２１によって地盤改良部２を設ける場合は、延伸方向に連続して設ける。例えば、断面の一部をラップさせることで、連続したソイルセメント柱列壁とすることができる。 Here, when providing the ground improvement part 2 by columnar improvement bodies 211,221, such as a soil cement pillar, it provides continuously in the extending | stretching direction. For example, a continuous soil cement column wall can be obtained by wrapping a part of the cross section.
長尺部２１は、土留め壁１の根入れ部分に連続するように隣接した位置に設けられる。長尺部２１の深度方向の長さは、設計によって任意に設定することができる。例えば、土留め壁１の根入れ長さと同程度、又は少し短い長さとすることができる。 The long portion 21 is provided at a position adjacent to the root portion of the retaining wall 1 so as to be continuous. The length of the long portion 21 in the depth direction can be arbitrarily set depending on the design. For example, it can be set to a length that is the same as or slightly shorter than the length of the earth retaining wall 1.
図１では、土留め壁１の先端は、硬質地盤Ｇ１には貫入されておらず、その上方の例えば軟弱地盤である地盤Ｇに留まっている。そして、長尺部２１も同様に、硬質地盤Ｇ１には貫入されず、その上方の地盤Ｇに留まっている。 In FIG. 1, the tip of the earth retaining wall 1 is not penetrated into the hard ground G1, but remains on the ground G that is, for example, soft ground above it. Similarly, the long portion 21 does not penetrate into the hard ground G1 and remains on the ground G above it.
長尺部２１は、例えば複数の柱状改良体２１１，・・・を連続させることで形成することができる。この長尺部２１を構成する柱状改良体２１１の長さは、すべて同程度の長さにする。 The long portion 21 can be formed by, for example, continuing a plurality of columnar improvement bodies 211,. All the lengths of the columnar improvement bodies 211 constituting the long portion 21 are set to the same length.
そして、短尺部２２は、長尺部２１に連続するように隣接した位置に設けられる。短尺部２２の深度方向の長さは、長尺部２１よりも短い長さで設計によって任意に設定することができる。本実施の形態では、長尺部２１の上半部の長さの範囲内に隣接するように短尺部２２を設ける。 And the short part 22 is provided in the position adjacent so that the long part 21 may be followed. The length of the short portion 22 in the depth direction can be arbitrarily set by design with a length shorter than that of the long portion 21. In the present embodiment, the short portion 22 is provided so as to be adjacent to the length of the upper half of the long portion 21.
短尺部２２は、例えば複数の柱状改良体２２１，・・・を連続させることで形成することができる。この短尺部２２を構成する柱状改良体２２１の長さは、すべて同程度の長さにする。 The short part 22 can be formed by, for example, continuing a plurality of columnar improvement bodies 221,. The lengths of the columnar improvements 221 constituting the short portion 22 are all set to the same length.
長尺部２１及び短尺部２２は、例えば上端面が掘削底面Ｓに露出するように設けられる。そして、長尺部２１と短尺部２２によって構成される地盤改良部２は、土留め壁１の幅方向に対して間隔を置いて複数設けられる。 The long portion 21 and the short portion 22 are provided such that the upper end surface is exposed to the excavation bottom surface S, for example. And the ground improvement part 2 comprised by the elongate part 21 and the short part 22 is provided with two or more spacings with respect to the width direction of the earth retaining wall 1. FIG.
次に、本実施の形態の土留め壁の支持構造の構築方法と、それが構築された際の掘削工事の工程について、図２を参照しながら説明する。
まず図２（ａ）に示すように、地表から地盤Ｇをオーガーで掘削しながらセメントミルクを注入することで、ソイルセメント柱１１を構築する。ソイルセメント柱１１は、土留め壁１の幅方向となる図２（ａ）の紙面直交方向に連続して設けられる。
Next, the construction method of the retaining wall support structure according to the present embodiment and the excavation process when the construction is constructed will be described with reference to FIG.
First, as shown in FIG. 2A, the soil cement pillar 11 is constructed by injecting cement milk while excavating the ground G from the ground surface with an auger. The soil cement pillar 11 is continuously provided in the direction perpendicular to the paper surface of FIG.
すなわち土留め壁１の幅方向の両側を隣接するソイルセメント柱１１，１１同士でラップさせることで、柱列壁を構築する。ソイルセメント柱１１には、必要に応じてＨ形鋼や鋼管などの芯材を挿入することもできる。 That is, the column wall is constructed by wrapping the soil cement columns 11, 11 adjacent to each other in the width direction of the earth retaining wall 1. A core material such as an H-shaped steel or a steel pipe can be inserted into the soil cement column 11 as necessary.
さらに図２（ｂ）に示すように、掘削した際に形成される掘削底面Ｓより下方地盤に、地盤改良部２となる柱状改良体２１１，２２１を設ける。この柱状改良体２１１，２２１は、例えばソイルセメント柱１１と同様に、地表から地盤Ｇをオーガーで掘削しながらセメントミルクを注入することで構築できる。 Further, as shown in FIG. 2 (b), columnar improvement bodies 211 and 221 that serve as the ground improvement portion 2 are provided on the ground below the bottom surface S of the excavation formed when excavating. These columnar improvement bodies 211 and 221 can be constructed by injecting cement milk while excavating the ground G from the ground surface with an auger, for example, as with the soil cement pillar 11.
ここで、柱状改良体２１１，２２１は、予定される掘削底面Ｓより下方地盤に設けられるため、セメントミルクの注入は、掘削底面Ｓ以下の深度で行われる。すなわち、掘削底面Ｓより上方では、オーガーは地盤Ｇ中を推進するだけで、地盤改良は行われない。 Here, since the columnar improvement bodies 211 and 221 are provided on the ground below the planned excavation bottom surface S, cement milk is injected at a depth equal to or less than the excavation bottom surface S. That is, above the excavation bottom surface S, the auger only propels the ground G, and the ground is not improved.
長尺部２１となる柱状改良体２１１は、隣接するソイルセメント柱１１に側面をラップさせることで連続して設けられる。また、その柱状改良体２１１に対しても、一部がラップする柱状改良体２１１を連続して設ける。さらに、最後の柱状改良体２１１の側面に一部がラップするように、短尺部２２の柱状改良体２２１を連続して設ける。 The columnar improvement bodies 211 that become the long portions 21 are continuously provided by wrapping the side surfaces of the adjacent soil cement columns 11. Moreover, the columnar improvement body 211 which a part wraps is provided continuously also about the columnar improvement body 211. FIG. Furthermore, the columnar improvement body 221 of the short part 22 is continuously provided so that a part wraps to the side surface of the last columnar improvement body 211.
長尺部２１となる柱状改良体２１１及び短尺部２２となる柱状改良体２２１の構築は、土留め壁１の幅方向に間隔を置いた位置においても行われる。こうして土留め壁１と、その下部を支持する地盤改良部２とを構築した後に、地盤Ｇの掘削を開始する。 Construction of the columnar improvement body 211 to be the long portion 21 and the columnar improvement body 221 to be the short portion 22 is also performed at positions spaced in the width direction of the retaining wall 1. After the earth retaining wall 1 and the ground improvement part 2 supporting the lower part are thus constructed, excavation of the ground G is started.
図２（ｃ）に示すように、地盤Ｇの掘削は、必要に応じて切梁１２を設置しながら行われる。予定した掘削底面Ｓまで掘り下げたときには、地盤改良部２の上端面が掘削底面Ｓと同じ高さとなる。 As shown in FIG.2 (c), excavation of the ground G is performed, installing the cut beam 12 as needed. When the excavation bottom surface S is dug down, the upper end surface of the ground improvement portion 2 becomes the same height as the excavation bottom surface S.
次に、本実施の形態の土留め壁の支持構造の作用について説明する。
このように構成された本実施の形態の土留め壁の支持構造では、土留め壁１の壁面に対して略直交する方向に延伸される控え壁状の地盤改良部２が、土留め壁１に隣接して設けられる長尺部２１と、それに隣接して上部にのみ設けられる短尺部２２とによって構成される。
Next, the operation of the retaining wall support structure of the present embodiment will be described.
In the retaining wall support structure of the present embodiment configured as described above, the retaining wall-shaped ground improvement portion 2 that extends in a direction substantially orthogonal to the wall surface of the retaining wall 1 includes the retaining wall 1. It is comprised by the elongate part 21 provided adjacent to, and the short part 22 provided only in the upper part adjacent to it.
図３に、本実施の形態の土留め壁の支持構造の作用を説明する概念図を示す。例えば、掘削に伴い土留め壁１が掘削底面Ｓ側に移動しようとすると、土留め壁１に隣接する長尺部２１の下端付近の仮想力点Ｐにおいて、せん断ひずみが発生し、破線で示したように上方に広がって伝達されることになる。 In FIG. 3, the conceptual diagram explaining the effect | action of the support structure of the earth retaining wall of this Embodiment is shown. For example, when the earth retaining wall 1 tries to move toward the excavation bottom surface S side with excavation, a shear strain is generated at a virtual force point P near the lower end of the long portion 21 adjacent to the earth retaining wall 1 and is indicated by a broken line. Thus, it spreads upward and is transmitted.
これに対して掘削底面Ｓ付近に、地盤Ｇよりも変形しにくい短尺部２２が地盤改良によって設けられていれば、せん断ひずみの広がりが抑えられて、土留め壁１の変位の発生を抑えることができる。すなわち、控え壁状の地盤改良部２を設けることによって、土留め壁１に必要とされる変位抑止性能が確保できる。 On the other hand, if the short portion 22 that is harder to deform than the ground G is provided near the excavation bottom surface S by the ground improvement, the spread of the shear strain can be suppressed and the occurrence of the displacement of the retaining wall 1 can be suppressed. Can do. That is, by providing the retaining wall-shaped ground improvement portion 2, the displacement suppression performance required for the retaining wall 1 can be ensured.
他方、短尺部２２の下方の地盤Ｇが地盤改良されていなくても、仮想力点Ｐを始点とするせん断ひずみの掘削底面Ｓに到達するような広がりには影響を与えないため、地盤改良の範囲を低減しても同等の変位抑止性能にすることができる。
要するに、長尺部２１に隣接する位置に部分的に短尺部２２が設けられていれば、必要とされる変位抑止性能を確保することができる。
On the other hand, even if the ground G below the short portion 22 is not improved, the extent of reaching the excavation bottom surface S of the shear strain starting from the virtual force point P is not affected. Even if this is reduced, equivalent displacement suppression performance can be achieved.
In short, if the short portion 22 is partially provided at a position adjacent to the long portion 21, the required displacement suppression performance can be ensured.
この結果、長尺部２１に隣接して同じ長さの地盤改良を行う場合と比べて、地盤改良範囲を低減できた分だけ、工費と工期を削減することができる。 As a result, compared with the case where the ground improvement of the same length is performed adjacent to the long portion 21, the construction cost and the construction period can be reduced by the amount that the ground improvement range can be reduced.
以下、前記実施の形態で説明した土留め壁の支持構造とは別の実施形態について、図４，５を参照しながら説明する。なお、前記実施の形態で説明した内容と同一乃至均等な部分の説明については、同一用語又は同一符号を付して説明する。 Hereinafter, an embodiment different from the retaining wall support structure described in the above embodiment will be described with reference to FIGS. The description of the same or equivalent parts as the contents described in the above embodiment will be described with the same terms or the same reference numerals.
本実施例の土留め壁の支持構造となる地盤改良部３は、土留め壁１の控え壁状に設けられる。すなわち土留め壁１の下部となる根入れ部分を、掘削空間側から支える控え壁（バットレス）として設けられる。 The ground improvement part 3 which becomes the support structure of the retaining wall of the present embodiment is provided in the shape of a retaining wall of the retaining wall 1. In other words, the base portion that is the lower portion of the retaining wall 1 is provided as a retaining wall (buttress) that supports the excavation space side.
地盤改良部３は、土留め壁１の壁面に対して略直交する方向に延伸される。この地盤改良部３は、土留め壁１に隣接して設けられる深度方向に長い長尺部３１と、長尺部３１の一部にのみ隣接して設けられる短尺部３２とによって主に構成される。本実施例では、短尺部３２を長尺部３１の下部に隣接して設ける場合について説明する。 The ground improvement part 3 is extended in a direction substantially orthogonal to the wall surface of the earth retaining wall 1. This ground improvement part 3 is mainly comprised by the elongate part 31 long in the depth direction provided adjacent to the earth retaining wall 1, and the short part 32 provided adjacent only to a part of long part 31. As shown in FIG. The In this embodiment, a case where the short part 32 is provided adjacent to the lower part of the long part 31 will be described.
地盤改良部３は、地盤に例えばセメント系の固化材を混入しながら撹拌することによって構築される。例えばソイルセメント柱などの柱状改良体３１１，３２１によって地盤改良部３を設ける場合は、延伸方向に連続して設ける。 The ground improvement unit 3 is constructed by stirring the ground while mixing, for example, a cement-based solidified material. For example, when providing the ground improvement part 3 by columnar improvement bodies 311 and 321 such as soil cement pillars, they are provided continuously in the extending direction.
長尺部３１は、土留め壁１の根入れ部分に連続するように隣接した位置に設けられる。長尺部３１の深度方向の長さは、設計によって任意に設定することができる。例えば、土留め壁１の根入れ長さと同程度、又は少し短い長さとすることができる。 The long portion 31 is provided at a position adjacent to the root portion of the retaining wall 1 so as to be continuous. The length of the long portion 31 in the depth direction can be arbitrarily set depending on the design. For example, it can be set to a length that is the same as or slightly shorter than the length of the earth retaining wall 1.
一方、短尺部３２は、長尺部３１に連続するように隣接した位置に設けられる。短尺部３２の深度方向の長さは、長尺部３１よりも短い長さで設計によって任意に設定することができる。本実施例では、長尺部３１の下半部の長さの範囲内に隣接するように短尺部３２を設ける。 On the other hand, the short portion 32 is provided at a position adjacent to the long portion 31 so as to be continuous. The length of the short portion 32 in the depth direction can be arbitrarily set by design with a length shorter than that of the long portion 31. In this embodiment, the short portion 32 is provided so as to be adjacent to the lower half of the long portion 31.
短尺部３２は、例えば複数の柱状改良体３２１，・・・を連続させることで形成することができる。この短尺部３２を構成する柱状改良体３２１の長さは、すべて同程度の長さにする。 The short part 32 can be formed by, for example, continuing a plurality of columnar improvement bodies 321,. The lengths of the columnar improvement bodies 321 constituting the short portion 32 are all set to the same length.
ここで、短尺部３２と掘削底面Ｓとの間には、地盤改良されていない地盤が介在されることになる。そして、長尺部３１と短尺部３２によって構成される地盤改良部３は、土留め壁１の幅方向に対して間隔を置いて複数設けられる。 Here, between the short portion 32 and the excavation bottom surface S, a ground that has not been improved is interposed. And the ground improvement part 3 comprised by the elongate part 31 and the short part 32 is provided with two or more intervals in the width direction of the retaining wall 1.
次に、本実施例の土留め壁の支持構造の作用について説明する。
このように構成された本実施例の土留め壁の支持構造では、土留め壁１の壁面に対して略直交する方向に延伸される控え壁状の地盤改良部３が、土留め壁１に隣接して設けられる長尺部３１と、それに隣接して下部にのみ設けられる短尺部３２とによって構成される。
Next, the operation of the retaining wall support structure of the present embodiment will be described.
In the retaining wall support structure of the present embodiment configured as described above, the retaining wall-shaped ground improvement portion 3 extending in a direction substantially orthogonal to the wall surface of the retaining wall 1 is provided on the retaining wall 1. It is comprised by the elongate part 31 provided adjacently, and the short part 32 provided only in the lower part adjacent to it.
図５に、本実施例の土留め壁の支持構造の作用を説明する概念図を示す。例えば、掘削に伴い土留め壁１が掘削底面Ｓ側に移動しようとすると、土留め壁１に隣接する長尺部３１の下端付近の仮想力点Ｐにおいて、せん断ひずみが発生し、破線で示したように上方に広がって伝達されることになる。 In FIG. 5, the conceptual diagram explaining the effect | action of the support structure of the earth retaining wall of a present Example is shown. For example, when the earth retaining wall 1 tries to move to the excavation bottom surface S side with excavation, a shear strain is generated at the virtual force point P near the lower end of the long portion 31 adjacent to the earth retaining wall 1 and is indicated by a broken line. Thus, it spreads upward and is transmitted.
これに対して仮想力点Ｐ付近に、地盤Ｇよりも変形しにくい長尺部３１及び短尺部３２が地盤改良によって設けられていれば、せん断ひずみの発生源付近において広がりが抑えられて、土留め壁１の変位の発生を抑えることができる。すなわち、控え壁状の地盤改良部３を設けることによって、土留め壁１に必要とされる変位抑止性能が確保できる。 On the other hand, if the long portion 31 and the short portion 32 that are less likely to be deformed than the ground G are provided near the virtual force point P by the ground improvement, the spread is suppressed in the vicinity of the shear strain source, and the earth retaining The occurrence of displacement of the wall 1 can be suppressed. That is, by providing the retaining wall-shaped ground improvement portion 3, the displacement suppression performance required for the retaining wall 1 can be ensured.
他方、短尺部３２の上方の地盤Ｇが地盤改良されていなくても、仮想力点Ｐ付近で抑制されたせん断ひずみはそれ以上に広がって周辺地盤に影響を与え難くなるため、地盤改良の範囲を低減しても同等の変位抑止性能にすることができる。
要するに、長尺部３１に隣接する位置に部分的に短尺部３２が設けられていれば、必要とされる変位抑止性能を確保することができる。
On the other hand, even if the ground G above the short portion 32 is not improved, the shear strain suppressed in the vicinity of the virtual force point P spreads further and hardly affects the surrounding ground. Even if it is reduced, equivalent displacement suppression performance can be achieved.
In short, if the short portion 32 is partially provided at a position adjacent to the long portion 31, the required displacement suppression performance can be ensured.
この結果、長尺部３１に隣接して同じ長さの地盤改良を行う場合と比べて、地盤改良範囲を低減できた分だけ、工費と工期を削減することができる。
なお、他の構成及び作用効果については、前記実施の形態と略同様であるので説明を省略する。
As a result, compared with the case where the ground improvement of the same length is performed adjacent to the long portion 31, the construction cost and the construction period can be reduced by the amount that the ground improvement range can be reduced.
Other configurations and operational effects are substantially the same as those in the above-described embodiment, and thus description thereof is omitted.
以上、図面を参照して、本発明の実施の形態を詳述してきたが、具体的な構成は、この実施の形態及び実施例に限らず、本発明の要旨を逸脱しない程度の設計的変更は、本発明に含まれる。 The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the embodiment and the example, and the design change is within a range not departing from the gist of the present invention. Are included in the present invention.
例えば前記実施の形態及び実施例では、土留め壁１の先端や地盤改良部２，３の先端を硬質地盤Ｇ１に貫入させない場合について説明したが、これに限定されるものではなく、土留め壁や地盤改良部の先端を硬質地盤Ｇ１に貫入させた土留め壁の支持構造にすることもできる。 For example, in the said embodiment and Example, although the case where the front-end | tip of the earth retaining wall 1 and the front-end | tip of the ground improvement parts 2 and 3 were not penetrated into the hard ground G1 was demonstrated, it is not limited to this, The earth retaining wall It is also possible to provide a retaining wall support structure in which the tip of the ground improvement portion is inserted into the hard ground G1.
また、前記実施の形態及び実施例では、1列の柱状改良体２１１，２２１（３１１，３２１）によって形成される地盤改良部２（３）について説明したが、これに限定されるものではなく、柱状改良体を土留め壁の幅方向に連続して複数列設けることによって厚みのある地盤改良部とすることもできる。 Moreover, in the said embodiment and Example, although the ground improvement part 2 (3) formed by the columnar improvement body 211,221 (311,321) of 1 row was demonstrated, it is not limited to this, A thick ground improvement part can also be obtained by providing a plurality of rows of columnar improvement bodies continuously in the width direction of the retaining wall.
１ ：土留め壁
２ ：地盤改良部
２１ ：長尺部
２２ ：短尺部
２１１，２２１ ：柱状改良体
３ ：地盤改良部
３１ ：長尺部
３２ ：短尺部
３１１，３２１ ：柱状改良体
Ｇ ：地盤
Ｓ ：掘削底面
1: Earth retaining wall 2: Ground improvement part 21: Long part 22: Short part 211, 221: Columnar improvement body 3: Ground improvement part 31: Long part 32: Short part 311, 321: Columnar improvement body G: Ground S: Bottom of excavation
Claims (3)
前記地盤改良部は、土留め壁の壁面に対して略直交する方向に延伸されるとともに、前記土留め壁に隣接して設けられる深度方向に長い長尺部と、前記長尺部の上部又は下部にのみ隣接して設けられる短尺部とを備えていることを特徴とする土留め壁の支持構造。 A retaining wall support structure in which a retaining wall-shaped ground improvement part is provided on the ground below the bottom of the excavation,
The ground improvement portion is extended in a direction substantially orthogonal to the wall surface of the retaining wall, and a long portion that is long in the depth direction provided adjacent to the retaining wall, and an upper portion of the long portion or A retaining wall support structure comprising a short portion provided adjacent to only a lower portion.
The earth retaining wall support structure according to claim 1 or 2, wherein the ground improvement portion is formed by continuously providing a columnar improvement body.
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| JPH07127064A (en) * | 1993-11-08 | 1995-05-16 | Takenaka Komuten Co Ltd | Buttress type earth retaining excavating construction method |
| JPH07197450A (en) * | 1993-12-28 | 1995-08-01 | Kokune Kensetsu Kk | Earth retaining wall in soft ground and soil improvement method by use thereof |
| JP2000303466A (en) * | 1999-04-20 | 2000-10-31 | Fudo Constr Co Ltd | Earth retaining method |
| JP2002275921A (en) * | 2001-03-13 | 2002-09-25 | Toda Constr Co Ltd | Reversed placing method |
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