JP6909101B2 - Embankment widening method and embankment - Google Patents

Embankment widening method and embankment Download PDF

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JP6909101B2
JP6909101B2 JP2017162217A JP2017162217A JP6909101B2 JP 6909101 B2 JP6909101 B2 JP 6909101B2 JP 2017162217 A JP2017162217 A JP 2017162217A JP 2017162217 A JP2017162217 A JP 2017162217A JP 6909101 B2 JP6909101 B2 JP 6909101B2
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embankment
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connecting layer
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隆弘 深田
隆弘 深田
山田 孝弘
孝弘 山田
和田 拓也
拓也 和田
小島 謙一
謙一 小島
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Railway Technical Research Institute
West Japan Railway Co
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West Japan Railway Co
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Description

本発明は、鉄道等における盛土を拡幅する盛土拡幅工法及び拡幅された盛土に関する。 The present invention relates to an embankment widening method for widening an embankment in a railway or the like and an embankment widened.

鉄道において、既存の線路の脇に新たな線路を増設する腹付け線増が行われることがある。盛土区間で腹付線増が行われる場合、盛土が拡幅される。 In railroads, an additional line may be added to add a new line to the side of an existing line. If the abdominal line is increased in the embankment section, the embankment will be widened.

従来から、盛土を拡幅する工法として、土留擁壁を構築する工法が知られている(例えば、特許文献1参照)。この工法では、既設盛土の近くに土留擁壁を構築し、既設盛土と土留擁壁の間に盛土を施す。しかし、この工法は、コンクリート製の土留擁壁を構築するので、施工コストが高くなる。このため、盛土を拡幅する場合、このような土留擁壁を構築せずに、既設盛土に腹付盛土(新設盛土)を施工することが多い。 Conventionally, as a method of widening the embankment, a method of constructing an earth retaining wall has been known (see, for example, Patent Document 1). In this construction method, a retaining wall is constructed near the existing embankment, and an embankment is applied between the existing embankment and the retaining wall. However, this method constructs a concrete retaining wall, which increases the construction cost. For this reason, when widening the embankment, it is often the case that an embankment with a belly (new embankment) is constructed on the existing embankment without constructing such a retaining wall.

既設の盛土に腹付して新たに盛土を施工する場合は、既設盛土に対する有害な沈下等の問題、新旧盛土の接続部におけるすべり等の問題が生じないようにするとともに、線路横断方向の路床の剛性が大きく変化しないような処理が設計標準で求められている(非特許文献1、3.3.1腹付盛土参照)。新設盛土と既設盛土との境界は、すべりが生じたり、水の通路となる等、弱点となりやすい。このため、従来は、腹付盛土を施工する際には、既設盛土に段切りが施工されていた。 When constructing a new embankment on the existing embankment, prevent problems such as harmful subsidence to the existing embankment and slippage at the connection between the old and new embankments, and the road in the crossing direction of the track. A design standard requires a treatment that does not significantly change the rigidity of the floor (see Non-Patent Document 1, 3.3.1 Embankment with belly). The boundary between the new embankment and the existing embankment tends to be a weak point, such as slippage and water passage. For this reason, conventionally, when constructing an embankment with a belly, a step cutting was performed on the existing embankment.

従来の盛土拡幅工法を図7(a)〜(c)を参照して説明する。図7(a)に示すような既設盛土101ののり面111を、図7(b)に示すように、階段状に掘削して段切り112が施工される。そして、図7(c)に示すように、腹付盛土103が施工される。既設盛土101と腹付盛土103は、段切り112が接続部となる。 The conventional embankment widening method will be described with reference to FIGS. 7 (a) to 7 (c). As shown in FIG. 7 (b), the slope 111 of the existing embankment 101 as shown in FIG. 7 (a) is excavated in a stepped manner to construct the step cutting 112. Then, as shown in FIG. 7 (c), the abdominal embankment 103 is constructed. The step cut 112 serves as a connecting portion between the existing embankment 101 and the embankment 103 with a belly.

しかし、このような段切り112を施工するために、既設盛土101を大きく掘削する必要があり、場合によっては、この掘削範囲が既設盛土101の施工基面113に侵入してしまうことがある(図7(b)参照)。そのような場合、施工基面近辺での土留め施工等により、工事が大掛かりとなっていた。なお、施工基面は、路盤の高さの基準面であり(非特許文献2、112参照)、盛土上部の面である。 However, in order to construct such a step cut 112, it is necessary to excavate a large amount of the existing embankment 101, and in some cases, this excavation range may invade the construction base surface 113 of the existing embankment 101 (). See FIG. 7 (b)). In such a case, the construction was large-scale due to the earth retaining work near the construction base surface. The construction base surface is a reference surface for the height of the roadbed (see Non-Patent Documents 2 and 112), and is the surface of the upper part of the embankment.

特開平7−102507号公報Japanese Unexamined Patent Publication No. 7-102507

国土交通省鉄道局監修 「鉄道構造物等設計標準・同解説 土構造物」丸善出版 平成25年改編Supervised by the Railway Bureau of the Ministry of Land, Infrastructure, Transport and Tourism "Design Standards for Railway Structures and Explanations of Soil Structures" Maruzen Publishing Co., Ltd. Reorganized in 2013 JIS E1001:2001 「鉄道−線路用語」JIS E1001: 2001 "Railway-railroad terminology"

本発明は、上記問題を解決するものであり、盛土を拡幅する際に、既設盛土への段切りの施工を不要とすることを目的とする。 The present invention solves the above-mentioned problems, and an object of the present invention is to eliminate the need for step cutting on an existing embankment when widening the embankment.

本発明の盛土拡幅工法は、既設盛土に腹付盛土を施工して盛土を拡幅する工法であって、既設盛土ののり面に接続層を設ける工程と、前記接続層の上に土を盛って腹付盛土を施工する工程とを有し、前記接続層は、透水性を有し、その内部摩擦角が前記既設盛土の内部摩擦角より大きく、N値が前記既設盛土及び腹付盛土のN値より大きく、前記腹付盛土側の面に複数の段を有することを特徴とする。 The embankment widening method of the present invention is a method of constructing an embankment with an abdomen on an existing embankment to widen the embankment. The connection layer has a water permeability, the internal friction angle thereof is larger than the internal friction angle of the existing embankment, and the N value is N of the existing embankment and the embankment. It is larger than the value and is characterized by having a plurality of steps on the surface on the side of the embankment with a belly.

この盛土拡幅工法において、前記接続層は、合成樹脂シートから成る型枠と、その型枠に充填された透水性を有する固形材料とを有する。 In this embankment widening method, the connecting layer includes a mold made of a synthetic resin sheet, that having a a solid material having been water-permeable filling in the mold.

この盛土拡幅工法において、前記型枠は、ジオセルであり、前記透水性を有する固形材料は、複数の砕石であることが好ましい。 In this embankment widening method, it is preferable that the formwork is a geocell and the solid material having water permeability is a plurality of crushed stones.

本発明の盛土は、既設盛土に腹付盛土を施工して拡幅された盛土であって、前記既設盛土と腹付盛土との間に接続層を備え、前記接続層は、透水性を有し、その内部摩擦角が前記既設盛土の内部摩擦角より大きく、N値が前記既設盛土及び腹付盛土のN値より大きく、前記腹付盛土側の面に複数の段を有することを特徴とする。 The embankment of the present invention is an embankment widened by constructing an embankment with a belly on an existing embankment, and includes a connecting layer between the existing embankment and the embankment with a belly, and the connecting layer has water permeability. The internal friction angle is larger than the internal friction angle of the existing embankment, the N value is larger than the N value of the existing embankment and the abdominal embankment, and the surface on the abdominal embankment side has a plurality of steps.

この盛土において、前記接続層は、合成樹脂シートから成る型枠と、その型枠に充填された透水性を有する固形材料とを有する。 In this embankment, the connecting layer includes a mold made of a synthetic resin sheet, that having a a solid material having been water-permeable filling in the mold.

この盛土において、前記型枠は、ジオセルであり、前記透水性を有する固形材料は、複数の砕石であることが好ましい。 In this embankment, the formwork is preferably a geocell, and the water-permeable solid material is preferably a plurality of crushed stones.

本発明の盛土拡幅工法及び盛土によれば、盛土を拡幅する際に接続層が設けられるので、既設盛土への段切りの施工が不要となる。接続層は、透水性を有するので、水はけが良く、弱点となるような水の通路とならない。また、接続層は、その内部摩擦角が既設盛土の内部摩擦角より大きいので、既設盛土とのすべりが防がれる。また、接続層は、腹付盛土側の面に複数の段を有するので、腹付盛土とのすべりが防がれ、腹付盛土の沈下が低減される。また、接続層は、N値が既設盛土のN値より大きいので、安定な盤構造となって、腹付盛土の荷重を支えることができ、腹付盛土の沈下が低減される。また、接続層は、N値が腹付盛土のN値より大きいので、腹付盛土の荷重が分散して下に伝達され、既設盛土の沈下が低減される。 According to the embankment widening method and the embankment of the present invention, since the connecting layer is provided when the embankment is widened, it is not necessary to perform step cutting on the existing embankment. Since the connecting layer has water permeability, it drains well and does not serve as a weak point for water passages. Further, since the internal friction angle of the connecting layer is larger than the internal friction angle of the existing embankment, slippage with the existing embankment can be prevented. Further, since the connecting layer has a plurality of steps on the surface on the side of the abdominal embankment, slippage with the abdominal embankment is prevented and the settlement of the abdominal embankment is reduced. Further, since the N value of the connecting layer is larger than the N value of the existing embankment, it has a stable board structure, can support the load of the abdominal embankment, and reduces the settlement of the abdominal embankment. Further, since the N value of the connecting layer is larger than the N value of the abdominal embankment, the load of the abdominal embankment is dispersed and transmitted downward, and the subsidence of the existing embankment is reduced.

(a)〜(c)は本発明の一実施形態に係る盛土拡幅工法を時系列順に示す断面構成図、(c)は本発明の一実施形態に係る盛土の断面構成図。(A) to (c) are sectional views showing the embankment widening method according to one embodiment of the present invention in chronological order, and (c) is a sectional view of the embankment according to one embodiment of the present invention. 同工法における接続層の部分斜視図。Partial perspective view of the connection layer in the same construction method. 同盛土の数値シミュレーションにおけるモデルを示す図。The figure which shows the model in the numerical simulation of the embankment. 同数値シミュレーションにおける地盤区分図。Ground division map in the same numerical simulation. 試験盛土の断面構成図。Cross-sectional block diagram of the test embankment. 前記数値シミュレーションにおける照査点を示す図。The figure which shows the check point in the numerical simulation. (a)〜(c)従来の盛土拡幅工法を時系列順に示す断面構成図。(A)-(c) Cross-sectional block diagram showing the conventional embankment widening method in chronological order.

本発明の一実施形態に係る盛土拡幅工法を図1(a)〜(c)及び図2を参照して説明する。この盛土拡幅工法は、既設盛土に腹付盛土を施工して盛土を拡幅する工法である。図1(a)に示すように、拡幅する対象の盛土は、既設盛土1である。 The embankment widening method according to the embodiment of the present invention will be described with reference to FIGS. 1 (a) to 1 (c) and FIG. This embankment widening method is a method of widening the embankment by constructing an embankment with a belly on the existing embankment. As shown in FIG. 1A, the embankment to be widened is the existing embankment 1.

図1(b)に示すように、この盛土拡幅工法は、既設盛土1ののり面11に接続層2を設ける工程を有する。 As shown in FIG. 1 (b), this embankment widening method includes a step of providing a connecting layer 2 on the slope 11 of the existing embankment 1.

次に、図1(c)に示すように、接続層2の上に土を盛って腹付盛土3を施工する工程を有する。すなわち、腹付盛土3は、新設盛土である。このような工程により、拡幅された盛土4が作られる。 Next, as shown in FIG. 1 (c), there is a step of piling soil on the connecting layer 2 to construct the abdominal embankment 3. That is, the belly embankment 3 is a new embankment. By such a process, the widened embankment 4 is made.

接続層2は、透水性を有し、その内部摩擦角が既設盛土1の内部摩擦角より大きく、N値が既設盛土1及び腹付盛土3のN値より大きく、腹付盛土3側の面に複数の段21を有する。 The connecting layer 2 has water permeability, its internal friction angle is larger than the internal friction angle of the existing embankment 1, the N value is larger than the N value of the existing embankment 1 and the abdominal embankment 3, and the surface on the abdominal embankment 3 side. Has a plurality of stages 21.

図2に示すように、接続層2は、型枠22と、透水性を有する固形材料23とを有する。型枠22は、合成樹脂シートから成る。固形材料23は、型枠22に充填される。 As shown in FIG. 2, the connecting layer 2 has a mold 22 and a water-permeable solid material 23. The mold 22 is made of a synthetic resin sheet. The solid material 23 is filled in the mold 22.

型枠22は、ジオセルである。透水性を有する固形材料23は、複数の砕石である。 The formwork 22 is a geocell. The water-permeable solid material 23 is a plurality of crushed stones.

本発明の一実施形態に係る盛土4を図1(c)及び図2を参照して説明する。この盛土4は、既設盛土1に腹付盛土3を施工して拡幅されている。盛土4は、既設盛土1と腹付盛土3との間に接続層2を備える。接続層2は、透水性を有し、その内部摩擦角が既設盛土1の内部摩擦角より大きく、N値が既設盛土1及び腹付盛土3のN値より大きく、腹付盛土3側の面に複数の段21を有する(図1(c)参照)。 The embankment 4 according to the embodiment of the present invention will be described with reference to FIGS. 1 (c) and 2. The embankment 4 is widened by constructing an embankment 3 with a belly on the existing embankment 1. The embankment 4 includes a connecting layer 2 between the existing embankment 1 and the embankment 3 with a belly. The connecting layer 2 has water permeability, its internal friction angle is larger than the internal friction angle of the existing embankment 1, the N value is larger than the N value of the existing embankment 1 and the abdominal embankment 3, and the surface on the abdominal embankment 3 side. Has a plurality of stages 21 (see FIG. 1 (c)).

この盛土4は、前記の盛土拡幅工法によって作られる。したがって、接続層2の構成は、その盛土拡幅工法における接続層2と同じである(図2参照)。 The embankment 4 is made by the above-mentioned embankment widening method. Therefore, the structure of the connecting layer 2 is the same as that of the connecting layer 2 in the embankment widening method (see FIG. 2).

盛土4について、さらに詳述する。既設盛土1及び拡幅された盛土4は、例えば、鉄道の盛土であり、断面が略台形である(図1(c)参照)。盛土とは、土を盛って作られた土構造物である。 The embankment 4 will be described in more detail. The existing embankment 1 and the widened embankment 4 are, for example, railway embankments and have a substantially trapezoidal cross section (see FIG. 1 (c)). An embankment is a soil structure made by piling up soil.

前述したように、接続層2は、その内部摩擦角が既設盛土1の内部摩擦角より大きい。 As described above, the internal friction angle of the connecting layer 2 is larger than the internal friction angle of the existing embankment 1.

ここで、内部摩擦角について説明する。土が外力を受けると、土の中にせん断応力τ[kN/m]が生じ、その土の中にせん断抵抗を超える箇所があると、せん断破壊が起こる。せん断破壊において、破壊する面をすべり面といい、せん断応力τに抵抗する最大のせん断抵抗をせん断強さs[kN/m]という。 Here, the internal friction angle will be described. When the soil receives an external force, a shear stress τ [kN / m 2 ] is generated in the soil, and if there is a part in the soil that exceeds the shear resistance, shear failure occurs. In shear fracture, the fractured surface is called the slip surface, and the maximum shear resistance that resists the shear stress τ is called the shear strength s [kN / m 2 ].

土のせん断強さsは、クーロンの式により、次のように表される。 The shear strength s of soil is expressed by Coulomb's equation as follows.

s=c+σ・tanφ s = c + σ ・ tanφ

ここに、cは土の粘着力[kN/m]、σは土のすべり面に働く垂直応力[kN/m]、φは土の内部摩擦角[°]である。 Here, c is the adhesive force of the soil [kN / m 2 ], σ is the normal stress acting on the slip surface of the soil [kN / m 2 ], and φ is the internal friction angle of the soil [°].

前述したように、接続層2は、N値が既設盛土1及び腹付盛土3のN値より大きい。 As described above, the N value of the connecting layer 2 is larger than the N value of the existing embankment 1 and the abdominal embankment 3.

ここで、N値について説明する。N値は、土の強度を表す数値であり、日本工業規格「標準貫入試験方法」(JIS A1219:2013)に規定されている。標準貫入試験(SPT)は、SPTサンプラーを動的貫入することによって地盤の硬軟、締まり具合の判定、及び土層構成を把握するために行われる。N値は、SPTサンプラーを300mm打ち込むのに必要な打撃回数である。 Here, the N value will be described. The N value is a numerical value indicating the strength of soil and is specified in the Japanese Industrial Standards "Standard Penetration Test Method" (JIS A1219: 2013). The standard penetration test (SPT) is performed by dynamically penetrating an SPT sampler to determine the hardness and tightness of the ground and to grasp the soil layer composition. The N value is the number of hits required to drive the SPT sampler by 300 mm.

前述したように、接続層2は、腹付盛土3側の面に複数の段21を有する。すなわち、接続層2は、腹付盛土3に接続する面が階段状の形状を有する。 As described above, the connecting layer 2 has a plurality of steps 21 on the surface on the side of the abdominal embankment 3. That is, the connecting layer 2 has a stepped surface on the surface connecting to the abdominal embankment 3.

接続層2の構成について説明する(図2参照)。高さ方向に幅を有し、平面視で波形に成形された帯状の合成樹脂シートが複数用いられ、隣接する合成樹脂シートは、平面視でその波形の位相が180°相違し、1周期ごとに互いに接合される。これにより、合成樹脂シートで囲まれた空間領域が、平面を埋め尽くすように周期的に配列され、型枠22が構成される。この型枠22における前記空間領域に透水性を有する固形材料23が充填される。固形材料23が充填された型枠22を複数、既設盛土1ののり面11に階段状に積み上げることにより、接続層2が構成される。 The configuration of the connection layer 2 will be described (see FIG. 2). A plurality of strip-shaped synthetic resin sheets having a width in the height direction and formed into a corrugated shape in a plan view are used, and the adjacent synthetic resin sheets differ in the phase of the waveform by 180 ° in a plan view, and every cycle. Joined to each other. As a result, the spatial regions surrounded by the synthetic resin sheet are periodically arranged so as to fill the plane, and the formwork 22 is formed. The space region of the mold 22 is filled with a water-permeable solid material 23. The connecting layer 2 is formed by stacking a plurality of formwork 22 filled with the solid material 23 on the slope 11 of the existing embankment 1 in a stepped manner.

型枠22の合成樹脂シートは、例えば、高密度ポリエチレンシートである。透水性を向上させるために、型枠22は、複数の貫通孔24を有する。本実施形態では、この型枠22は、ジオセルである(例えば、特表2012−504058号公報参照)。透水性を有する固形材料23は、複数の砕石である。その砕石は、粒度調整砕石であり、締固めし易く、透水性が良い。なお、粒度調整砕石とは、破砕後ふるい分けしてほぼ一定のサイズにした砕石である。 The synthetic resin sheet of the mold 22 is, for example, a high-density polyethylene sheet. In order to improve the water permeability, the mold 22 has a plurality of through holes 24. In the present embodiment, the mold 22 is a geocell (see, for example, Japanese Patent Application Laid-Open No. 2012-504058). The water-permeable solid material 23 is a plurality of crushed stones. The crushed stone is a particle size-adjusted crushed stone, which is easy to compact and has good water permeability. The particle size-adjusted crushed stone is a crushed stone that has been crushed and then sieved to a substantially constant size.

このように、本実施形態によれば、盛土を拡幅する際に接続層2が設けられるので、既設盛土1への段切りの施工が不要となる。接続層2は、透水性を有するので、水はけが良く、弱点となるような水の通路とならない。また、接続層2は、その内部摩擦角が既設盛土1の内部摩擦角より大きいので、既設盛土1とのすべりが防がれる。また、接続層2は、腹付盛土3側の面に複数の段21を有するので、腹付盛土3とのすべりが防がれ、腹付盛土3の沈下が低減される。また、接続層2は、N値が既設盛土1のN値より大きいので、安定な盤構造となって、腹付盛土3の荷重を支えることができ、腹付盛土3の沈下が低減される。また、接続層2は、N値が腹付盛土3のN値より大きいので、腹付盛土3の荷重が分散して下に伝達され、既設盛土1の沈下が低減される。 As described above, according to the present embodiment, since the connecting layer 2 is provided when the embankment is widened, it is not necessary to perform step cutting on the existing embankment 1. Since the connecting layer 2 has water permeability, it drains well and does not serve as a water passage which is a weak point. Further, since the internal friction angle of the connecting layer 2 is larger than the internal friction angle of the existing embankment 1, slippage with the existing embankment 1 can be prevented. Further, since the connecting layer 2 has a plurality of steps 21 on the surface on the side of the abdominal embankment 3, slippage with the abdominal embankment 3 is prevented, and the subsidence of the abdominal embankment 3 is reduced. Further, since the N value of the connecting layer 2 is larger than the N value of the existing embankment 1, the board structure is stable, the load of the abdominal embankment 3 can be supported, and the subsidence of the abdominal embankment 3 is reduced. .. Further, since the N value of the connecting layer 2 is larger than the N value of the abdominal embankment 3, the load of the abdominal embankment 3 is dispersed and transmitted downward, and the subsidence of the existing embankment 1 is reduced.

上記の効果を定量的に確認するために、数値シミュレーション及び実物大の試験を行った。この数値シミュレーション及び試験について、図3〜図6を参照して説明する。 Numerical simulations and full-scale tests were conducted to quantitatively confirm the above effects. The numerical simulation and the test will be described with reference to FIGS. 3 to 6.

先ず、有限要素法による数値シミュレーションを行った。図3に示すように、数値シミュレーションにおいて、拡幅された盛土4は、断面が台形で、高さH=12m、底部の幅W=50mとした。基礎地盤5は、断面が長方形で、深さD=50mとした。基礎地盤5は、盛土4直下の基礎地盤51、その両側の基礎地盤52、53に区分した。基礎地盤51の幅は、W=50m、基礎地盤52の幅は、W52=115m、基礎地盤53の幅は、W53=115mとした。 First, a numerical simulation was performed by the finite element method. As shown in FIG. 3, in the numerical simulation, the widened embankment 4 has a trapezoidal cross section, a height H = 12 m, and a bottom width W = 50 m. The foundation ground 5 has a rectangular cross section and a depth of D = 50 m. The foundation ground 5 is divided into a foundation ground 51 directly below the embankment 4 and foundation grounds 52 and 53 on both sides thereof. The width of the foundation ground 51 was W = 50 m, the width of the foundation ground 52 was W52 = 115 m, and the width of the foundation ground 53 was W53 = 115 m.

計算のメッシュサイズは、盛土4が0.25m、盛土4の直下の基礎地盤51が2.5m、その両側の基礎地盤52、53が、3.5mとした。 The calculated mesh size was 0.25 m for the embankment 4, 2.5 m for the foundation ground 51 directly under the embankment 4, and 3.5 m for the foundation grounds 52 and 53 on both sides thereof.

図4に示すように、既設盛土1を既設盛土(深部)1aと既設盛土(表層部)1bに区分した。接続層2と腹付盛土3(新設盛土)を4段施工し、1段、2段、3段、4段の接続層2をそれぞれ、接続層201、202、203、204に区分し、1段、2段、3段、4段の腹付盛土3をそれぞれ、腹付盛土301、302、303、304に区分した。 As shown in FIG. 4, the existing embankment 1 was divided into the existing embankment (deep part) 1a and the existing embankment (surface layer part) 1b. The connection layer 2 and the abdominal embankment 3 (new embankment) are constructed in four stages, and the first, second, third, and fourth stages of the connection layer 2 are divided into connection layers 201, 202, 203, and 204, respectively, and one stage. The two-tiered, three-tiered, and four-tiered belly-filled embankments 3 were divided into belly-filled embankments 301, 302, 303, and 304, respectively.

このように区分した地盤の物性値を表1の通りとした。 Table 1 shows the physical characteristic values of the ground classified in this way.

Figure 0006909101
Figure 0006909101

表1の物性値において、内部摩擦角以外は、後述する実物大の試験における実際の値を用いた。接続層2の内部摩擦角43°は、型枠22を製造しているメーカーの技術資料(旭化成ジオテック技術レポート、基盤部ジオセル中詰め材の違いによる摩擦係数)に図示されている摩擦係数から算出した(0.94≒tan43°)。内部摩擦角φは、N値との関係が知られており、例えば、ペックの式φ=0.3N+27がある。接続層2以外の内部摩擦角φは、このペックの式を用い、表1のN値から算出した。 In the physical property values in Table 1, the actual values in the full-scale test described later were used except for the internal friction angle. The internal friction angle 43 ° of the connection layer 2 is calculated from the friction coefficient shown in the technical data of the manufacturer of the formwork 22 (Asahi Kasei Geotech Technical Report, friction coefficient due to the difference in the base geocell filling material). (0.94 ≈ tan 43 °). The relationship between the internal friction angle φ and the N value is known. For example, there is Peck's equation φ = 0.3N + 27. The internal friction angle φ other than the connection layer 2 was calculated from the N value in Table 1 using this Peck's formula.

接続層2を施工する場合だけでなく、比較例として、接続層2を施工しない場合についても数値シミュレーションを行った。その比較例(接続層無し)では、接続層2の物性値の代わりに既設盛土(表層部)1bの物性値を入力した。それ以外の条件は、接続層2ありの場合と同じにした。 Numerical simulation was performed not only when the connection layer 2 was constructed but also when the connection layer 2 was not constructed as a comparative example. In the comparative example (without connecting layer), the physical property value of the existing embankment (surface layer portion) 1b was input instead of the physical property value of the connecting layer 2. Other conditions were the same as when the connection layer 2 was present.

この数値シミュレーションの結果は、後述する。 The results of this numerical simulation will be described later.

次に、実物大の試験を行った。この試験は、上記の数値シミュレーションにおける腹付盛土の1段施工に相当する。図5に示すように、腹付盛土3の幅W1は10m、高さH1は2.7mとした。 Next, a full-scale test was conducted. This test corresponds to the one-step construction of the abdominal embankment in the above numerical simulation. As shown in FIG. 5, the width W1 of the abdominal embankment 3 was 10 m, and the height H1 was 2.7 m.

腹付盛土施工完了から10日後の沈下量を、点P1〜P5で測定した。すなわち、この試験では、点P1〜P5は測定点である。点P1は、既設盛土1ののり面である。点P2は、腹付盛土3の上面における既設盛土1との境界近傍である。点P3は、腹付盛土3の上面中央である。点P4は、既設盛土1ののり面(地中部)である。点P5は、接続層2上の面(地中部)である。 The amount of subsidence 10 days after the completion of the abdominal embankment construction was measured at points P1 to P5. That is, in this test, points P1 to P5 are measurement points. Point P1 is the slope of the existing embankment 1. The point P2 is near the boundary with the existing embankment 1 on the upper surface of the abdominal embankment 3. The point P3 is the center of the upper surface of the abdominal embankment 3. Point P4 is the slope (underground) of the existing embankment 1. The point P5 is a surface (underground part) on the connecting layer 2.

接続層2を施工する場合だけでなく、比較例として、接続層2を施工しない場合についても試験を行った。その比較例(接続層無し)では、点P5は無い。 The test was conducted not only when the connection layer 2 was constructed but also when the connection layer 2 was not constructed as a comparative example. In the comparative example (without connecting layer), there is no point P5.

前記の数値シミュレーションにおいても、腹付盛土3の1段施工について沈下量を計算した。沈下量の照査点は、実物大の試験の測定点(点P1〜P5)と同じ箇所とした。 Also in the above numerical simulation, the settlement amount was calculated for the one-step construction of the abdominal embankment 3. The check point for the amount of subsidence was the same as the measurement point (points P1 to P5) of the full-scale test.

上述したような腹付盛土の1段施工について、試験における測定値と数値シミュレーションにおける計算値を表2に示す。 Table 2 shows the measured values in the test and the calculated values in the numerical simulation for the one-stage construction of the abdominal embankment as described above.

Figure 0006909101
Figure 0006909101

表2からわかるように、1段施工での実物大の試験においては、測定点P1〜P3の沈下量は、ほとんど計測されなかった。測定値と計算値はオーダー(桁数)が合っており、測定値は計算値の半分程度の差異であるので、数値シミュレーションの結果は妥当と考えられる。 As can be seen from Table 2, the settlement amount of the measurement points P1 to P3 was hardly measured in the full-scale test in the one-stage construction. Since the measured value and the calculated value are in order (number of digits) and the measured value is a difference of about half of the calculated value, the result of the numerical simulation is considered to be appropriate.

特に、点P4の沈下量の測定値は、接続層なしの場合の6mmに対して、接続層ありでは4mmに低減され、接続層の効果が確認された。なお、試験では1段施工であるが、実際の施工は、4段施工であるので、実際の沈下量は、この試験の測定値の4倍程度になると推定される。したがって、接続層による沈下量の低減効果は、(6−4)×4=8mmと推定される。盛土上の軌道に対しては、数ミリメートルの低減は顕著な効果である。 In particular, the measured value of the settlement amount at the point P4 was reduced to 4 mm with the connecting layer from 6 mm without the connecting layer, and the effect of the connecting layer was confirmed. Although it is a one-step construction in the test, the actual construction is a four-step construction, so the actual settlement amount is estimated to be about four times the measured value in this test. Therefore, the effect of reducing the amount of settlement by the connecting layer is estimated to be (6-4) × 4 = 8 mm. For the orbit on the embankment, a reduction of a few millimeters is a significant effect.

次に、図6に示すように、腹付盛土3を4段まで施工した最終形の盛土4について、数値シミュレーションを行った。腹付盛土3は、4段の重層であり、下から順に腹付盛土1段301、腹付盛土2段302、腹付盛土3段303、及び腹付盛土4段304である。盛土4の最上部に軌道荷重15kN/mを加えた。 Next, as shown in FIG. 6, a numerical simulation was performed on the final form of the embankment 4 in which the abdominal embankment 3 was constructed up to 4 steps. The belly embankment 3 is a four-tiered layer, and is, from the bottom, a belly embankment 1 step 301, a belly embankment 2 steps 302, a belly embankment 3 steps 303, and a belly embankment 4 steps 304. An orbital load of 15 kN / m 2 was applied to the uppermost part of the embankment 4.

沈下量の照査点を三角で示す。点P11は、腹付盛土1段301の上面における接続層2近傍である。点P12は、腹付盛土1段301の上面中央である。点P13は、腹付盛土1段301の上面近傍ののり面である。点P21は、腹付盛土2段302の上面における接続層2近傍である。点P22は、腹付盛土2段302の上面中央である。点P23は、腹付盛土2段302の上面近傍ののり面である。点P31は、腹付盛土3段303の上面における接続層2近傍である。点P32は、腹付盛土3段303の上面中央である。点P33は、腹付盛土3段303の上面近傍ののり面である。点P41は、腹付盛土4段304の上面における接続層2近傍である。点P42は、腹付盛土4段304の上面中央である。点P43は、腹付盛土4段304の上面近傍ののり面である。点Pi、点Pii、点Piii、点Pivは、それぞれ、腹付盛土1段301、腹付盛土2段302、腹付盛土3段303、腹付盛土4段304に接する既設盛土1ののり面である。 The points to be checked for the amount of subsidence are indicated by triangles. The point P11 is near the connecting layer 2 on the upper surface of the abdominal embankment 1st step 301. The point P12 is the center of the upper surface of the abdominal embankment 1st step 301. Point P13 is a slope near the upper surface of the abdominal embankment 1st step 301. The point P21 is near the connecting layer 2 on the upper surface of the abdominal embankment 2 steps 302. Point P22 is the center of the upper surface of the two-tiered embankment 302 with abdomen. Point P23 is a slope near the upper surface of the abdominal embankment 2 steps 302. Point P31 is near the connecting layer 2 on the upper surface of the abdominal embankment 3 steps 303. Point P32 is the center of the upper surface of the abdominal embankment 3 steps 303. Point P33 is a slope near the upper surface of the abdominal embankment 3 steps 303. Point P41 is near the connecting layer 2 on the upper surface of the abdominal embankment 4 steps 304. Point P42 is the center of the upper surface of the abdominal embankment 4 steps 304. Point P43 is a slope near the upper surface of the abdominal embankment 4 steps 304. Point Pi, point Pii, point Pii, and point Piv are the slopes of the existing embankment 1 in contact with the abdominal embankment 1st stage 301, the abdominal embankment 2nd stage 302, the abdominal embankment 3rd stage 303, and the abdominal embankment 4th stage 304, respectively. Is.

接続層2を施工する場合だけでなく、比較例として、接続層2を施工しない場合についても数値シミュレーションを行った。その比較例(接続層無し)では、接続層2の物性値の代わりに既設盛土(表層部)1bの物性値を入力した。それ以外の条件は、接続層2ありの場合と同じにした。 Numerical simulation was performed not only when the connection layer 2 was constructed but also when the connection layer 2 was not constructed as a comparative example. In the comparative example (without connecting layer), the physical property value of the existing embankment (surface layer portion) 1b was input instead of the physical property value of the connecting layer 2. Other conditions were the same as when the connection layer 2 was present.

腹付盛土3における各照査点における計算値を表3に示す。 Table 3 shows the calculated values at each check point in the belly embankment 3.

Figure 0006909101
Figure 0006909101

表3からわかるように、腹付盛土3の沈下量は、接続層2ありの場合が、接続層2なしの場合と比べ、9割程度に低減された。 As can be seen from Table 3, the amount of subsidence of the abdominal embankment 3 was reduced to about 90% in the case with the connecting layer 2 as compared with the case without the connecting layer 2.

既設盛土1における各照査点における計算値を表4に示す。 Table 4 shows the calculated values at each check point on the existing embankment 1.

Figure 0006909101
Figure 0006909101

表4からわかるように、既設盛土1ののり面においても、沈下量が若干低減された。 As can be seen from Table 4, the amount of subsidence was also slightly reduced on the slope of the existing embankment 1.

このように、数値シミュレーション及び実物大の試験を行った結果、盛土を拡幅する際に、接続層2を設けることによって腹付盛土3の沈下量が低減され、現行の設計標準(非特許文献1)を満足できることがわかった。また、従来の段切りは、施工に大型重機を使用する必要があったが、ジオセルを用いた接続層2は、大型重機を用いなくても人力で容易に施工できる。 As a result of conducting numerical simulations and full-scale tests in this way, when the embankment is widened, the amount of subsidence of the abdominal embankment 3 is reduced by providing the connecting layer 2, and the current design standard (Non-Patent Document 1). ) Was found to be satisfactory. Further, in the conventional step cutting, it is necessary to use a large heavy machine for construction, but the connection layer 2 using a geocell can be easily constructed manually without using a large heavy machine.

なお、本発明は、上記の実施形態の構成に限られず、発明の要旨を変更しない範囲で種々の変形が可能である。例えば、本発明の盛土拡幅工法及び盛土は、鉄道の盛土の拡幅に限定されず、道路の盛土の拡幅に用いてもよい。 The present invention is not limited to the configuration of the above embodiment, and various modifications can be made without changing the gist of the invention. For example, the embankment widening method and embankment of the present invention are not limited to the embankment widening of railways, and may be used for widening road embankments.

1 既設盛土
11 のり面
2 接続層
21 段
22 型枠(ジオセル)
23 固形材料(砕石)
3 腹付盛土(新設盛土)
4 盛土
1 Existing embankment 11 Slope 2 Connection layer 21 steps 22 Formwork (Geocell)
23 Solid material (crushed stone)
3 Embankment with belly (new embankment)
4 embankment

Claims (4)

既設盛土に腹付盛土を施工して盛土を拡幅する盛土拡幅工法であって、
既設盛土ののり面に接続層を設ける工程と、
前記接続層の上に土を盛って腹付盛土を施工する工程とを有し、
前記接続層は、透水性を有し、その内部摩擦角が前記既設盛土の内部摩擦角より大きく、N値が前記既設盛土及び腹付盛土のN値より大きく、前記腹付盛土側の面に複数の段を有し、合成樹脂シートから成る型枠と、その型枠に充填された透水性を有する固形材料とを有することを特徴とする盛土拡幅工法。
It is an embankment widening method that widens the embankment by constructing an embankment with a belly on the existing embankment.
The process of providing a connecting layer on the slope of the existing embankment,
It has a process of piling soil on the connecting layer and constructing a belly-filled embankment.
The connecting layer has water permeability, its internal friction angle is larger than the internal friction angle of the existing embankment, and the N value is larger than the N value of the existing embankment and the abdominal embankment. It has a plurality of stages, and molds made of a synthetic resin sheet, embankment widening method characterized by chromatic and solid material having a water permeability which is filled in the mold.
前記型枠は、ジオセルであり、
前記透水性を有する固形材料は、複数の砕石であることを特徴とする請求項に記載の盛土拡幅工法。
The formwork is a geocell
The embankment widening method according to claim 1 , wherein the solid material having water permeability is a plurality of crushed stones.
既設盛土に腹付盛土を施工して拡幅された盛土であって、
前記既設盛土と腹付盛土との間に接続層を備え、
前記接続層は、透水性を有し、その内部摩擦角が前記既設盛土の内部摩擦角より大きく、N値が前記既設盛土及び腹付盛土のN値より大きく、前記腹付盛土側の面に複数の段を有し、合成樹脂シートから成る型枠と、その型枠に充填された透水性を有する固形材料とを有することを特徴とする盛土。
It is an embankment that has been widened by constructing an embankment with a belly on the existing embankment.
A connecting layer is provided between the existing embankment and the embankment with a belly.
The connecting layer has water permeability, its internal friction angle is larger than the internal friction angle of the existing embankment, and the N value is larger than the N value of the existing embankment and the abdominal embankment. embankment which have a plurality of stages, to a mold made of a synthetic resin sheet, characterized in that organic and solid material having a water permeability which is filled in the mold.
前記型枠は、ジオセルであり、
前記透水性を有する固形材料は、複数の砕石であることを特徴とする請求項に記載の盛土。
The formwork is a geocell
The embankment according to claim 3 , wherein the solid material having water permeability is a plurality of crushed stones.
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