JP2016211363A - Method and structure for flow inhibition of slope ground - Google Patents

Method and structure for flow inhibition of slope ground Download PDF

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JP2016211363A
JP2016211363A JP2016084417A JP2016084417A JP2016211363A JP 2016211363 A JP2016211363 A JP 2016211363A JP 2016084417 A JP2016084417 A JP 2016084417A JP 2016084417 A JP2016084417 A JP 2016084417A JP 2016211363 A JP2016211363 A JP 2016211363A
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slope
ground
wall
parallel
orthogonal
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JP6739977B2 (en
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隆志 小原
Takashi Obara
隆志 小原
北本 幸義
Yukiyoshi Kitamoto
幸義 北本
悠介 中島
Yusuke Nakajima
悠介 中島
剛一 鬼木
Koichi Oniki
剛一 鬼木
柳澤 博
Hiroshi Yanagisawa
博 柳澤
宗宏 前田
Munehiro Maeda
宗宏 前田
武志 村上
Takeshi Murakami
武志 村上
昇 富樫
Noboru Togashi
昇 富樫
山田 岳峰
Takemine Yamada
岳峰 山田
田中 耕一
Koichi Tanaka
耕一 田中
真 北山
Makoto Kitayama
真 北山
淳 川村
Atsushi Kawamura
淳 川村
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Kajima Corp
Chemical Grouting Co Ltd
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Chemical Grouting Co Ltd
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  • Pit Excavations, Shoring, Fill Or Stabilisation Of Slopes (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a method and a structure for flow inhibition of a slope ground that enables the ground to be improved over a wide region with a small amount of improved soil, and stability of the slope ground to be enhanced.SOLUTION: Ground improvement is performed on a slope ground 27 at a prescribed interval in a direction parallel to the slope, and a parallel-to-slope wall 33 is constructed that is a ground improvement part. A construction interval of the parallel-to-slope wall 33 and a wall thickness of the parallel-to-slope wall 33 are set so that a slope slide safety factor of a composite ground exceeds 1, the slope slide safety factor being calculated using adhesive force of the composite ground derived from adhesive force of an unimproved part where ground improvement has not been performed and adhesive force of the parallel-to-slope wall 33 that is the ground improvement part. The parallel-to-slope wall 33 is improved to a depth necessary for suppressing excess pore water pressure and ensuring sliding of the slope. Also, ground improvement is performed on the slope ground 27 at a prescribed interval in a direction almost orthogonal to the slope, and an orthogonal-to-slope wall 35 is constructed that is a ground improvement part. The orthogonal-to-slope wall 35 is improved to a depth necessary for suppressing the excess pore water pressure.SELECTED DRAWING: Figure 2

Description

本発明は、斜面地盤の流動を抑制する方法および構造に関するものである。   The present invention relates to a method and a structure for suppressing the flow of slope ground.

斜面地盤では、豪雨等によって斜面がすべって崩壊する場合がある。また、鉱山の鉱さい集積場における基礎堤内の鉱さい(スライム)地盤のような軟弱な斜面地盤では、地震時に液状化やそれに伴う地盤の強度低下に起因した流動が生じる場合がある。そこで、斜面地盤では、豪雨時や地震時における地盤の安定性を高める必要がある。   On slope ground, the slope may slip and collapse due to heavy rain. In addition, in soft slope ground such as slag ground in the foundation dyke in the mine tailings accumulation site, there may be a flow due to liquefaction and accompanying ground strength reduction during an earthquake. Therefore, on slope ground, it is necessary to improve the stability of the ground during heavy rains and earthquakes.

豪雨等による斜面の地滑りを抑制する方法として、地表に浸透防止工を施工して地下水の浸透を防ぐ方法、薬液注入や杭の打設等により地盤を強化する方法等がある。また、地震時の斜面の流動を抑制する方法として、セメント等の固化材を原位置で撹拌し、地盤に固化体を造成する固化系地盤改良が有効と考えられ、堰堤と表層改良体と斜面の側部に形成されて非液状化層に着底または根入れされた側部改良体とを備える流動対策構造が提案されている(例えば、特許文献1参照)。   As a method of suppressing the landslide on the slope due to heavy rain, there are a method of preventing infiltration of groundwater by constructing a seepage prevention work on the ground surface, a method of strengthening the ground by injecting chemicals or placing piles, and the like. In addition, as a method of suppressing the flow of the slope during an earthquake, it is considered effective to improve the solidification system ground by stirring solidified material such as cement in-situ and creating a solidified body on the ground. There has been proposed a flow countermeasure structure including a side improvement body formed on the side portion of the base and bottomed or embedded in the non-liquefied layer (see, for example, Patent Document 1).

平坦な地盤においては、地震時の液状化を抑制し安定性を高めるための方法として、格子状に地盤を改良する方法が知られている(例えば、特許文献2、特許文献3参照)。   In a flat ground, a method of improving the ground in a lattice shape is known as a method for suppressing liquefaction during an earthquake and enhancing stability (see, for example, Patent Document 2 and Patent Document 3).

特開2016−3514号公報Japanese Patent Laying-Open No. 2006-3514 特開2002−302935号公報JP 2002-302935 A 特開2009−185546号公報JP 2009-185546 A

しかしながら、豪雨時および地震時の安定化対策を必要とする斜面が大規模な場合、対策コスト低減の観点から、改良範囲をできる限り削減する必要がある。その際、地震の液状化対策として用いられる格子状に地盤を改良する方法が有効だが、従来の格子状改良の設計法は、平坦地盤を前提として未改良部の液状化を許容しない考え方が主流であり、鉱さい集積場のようなある程度の液状化が許容されるような斜面地盤にとって必ずしも合理的でない場合があり、斜面の安定に不必要な改良範囲が含まれることが懸念される。   However, when the slopes that require stabilization measures during heavy rains and earthquakes are large, it is necessary to reduce the improvement range as much as possible from the viewpoint of reducing the cost of the measures. At that time, the method of improving the ground in a lattice shape used as an earthquake liquefaction countermeasure is effective, but the conventional design method of lattice improvement is mainly based on the concept of not allowing liquefaction of unimproved parts on the assumption of flat ground. In some cases, it is not always reasonable for slope ground where a certain level of liquefaction is permitted, such as a mine dump, and there is concern that an unnecessary improvement range for slope stability may be included.

本発明は、前述した問題点に鑑みてなされたもので、その目的とすることは、少ない改良土量で地盤を広範囲にわたって適切に改良し、斜面地盤の安定性を高めることができる斜面地盤の流動抑制方法および構造である。   The present invention has been made in view of the above-described problems, and its purpose is to appropriately improve the ground over a wide range with a small amount of improved soil, and to improve the stability of the slope ground. A flow suppression method and structure.

前述した目的を達成するために、第1の発明は、斜面地盤の流動を抑制する方法であって、斜面地盤に、斜面と平行方向に所定の間隔で地盤改良を行い、地盤改良部である斜面平行壁を施工する工程aを具備し、前記所定の間隔および前記斜面平行壁の壁厚は、地盤改良を行っていない未改良部の粘着力と前記地盤改良部の粘着力とから求められる複合地盤の粘着力を用いて算出した前記複合地盤の滑り安全率が1を超えるように設定され、前記斜面平行壁は過剰間隙水圧の抑制と斜面の滑り抑制に必要な深度まで改良され、前記斜面平行壁の壁面摩擦により前記斜面地盤の滑りを抑制することを特徴とする斜面地盤の流動抑制方法である。過剰間隙水圧とは、液状化の原因である地震時に上昇する土中内の水圧である。   In order to achieve the above-described object, the first invention is a method for suppressing the flow of a slope ground, and is a ground improvement portion that performs ground improvement on a slope ground at a predetermined interval in a direction parallel to the slope. A step a for constructing a slope parallel wall, wherein the predetermined interval and the wall thickness of the slope parallel wall are obtained from an adhesive force of an unimproved portion not subjected to ground improvement and an adhesive force of the ground improvement portion. The slippage safety factor of the composite ground calculated using the adhesive strength of the composite ground is set to exceed 1, and the slope parallel wall is improved to a depth necessary for suppressing excess pore water pressure and slope slippage, A slope ground flow suppressing method, wherein slippage of the slope ground is suppressed by wall friction of a slope parallel wall. Excess pore water pressure is the water pressure in the soil that rises during an earthquake that causes liquefaction.

第1の発明では、前記斜面平行壁を、平面視でジグザグ形状に形成してもよい。
また、前記斜面地盤に、前記斜面と略直交する方向に所定の間隔で地盤改良を行い、地盤改良部である斜面直交壁を施工する工程bをさらに具備し、前記斜面直交壁は、過剰間隙水圧抑制に必要な深度だけ改良され、前記斜面直交壁により前記斜面地盤の液状化を抑制する場合もある。
In the first invention, the inclined parallel wall may be formed in a zigzag shape in plan view.
Further, the method further comprises a step (b) of improving the ground at a predetermined interval in a direction substantially orthogonal to the slope and constructing a slope orthogonal wall as a ground improvement portion on the slope ground, the slope orthogonal wall having an excess gap In some cases, the depth is improved by a depth required for water pressure suppression, and the liquefaction of the slope ground is suppressed by the slope orthogonal wall.

斜面直交壁を施工する場合、必要に応じて、前記斜面平行壁と前記斜面直交壁との交差部に、杭を設置してもよい。
また、少なくとも一部の前記斜面直交壁の深度は、前記斜面平行壁の深度よりも浅くてもよい。
When constructing a slope orthogonal wall, you may install a pile in the cross | intersection part of the said slope parallel wall and the said slope orthogonal wall as needed.
Moreover, the depth of at least a part of the orthogonal wall of the slope may be shallower than the depth of the parallel wall of the slope.

第1の発明では、地盤改良で発生する吹上土を用いて、前記斜面地盤の表層を被覆する土被り部を設置してもよい。吹上土とは、地盤内で固化材を撹拌したときに地上に吹き上がってくる土と固化材の混成物である。
また、必要に応じて、前記斜面地盤の表層に凸部が形成され、前記凸部が前記斜面平行壁の頂部近傍に接続される。
In 1st invention, you may install the earth covering part which coat | covers the surface layer of the said slope ground using the blowing soil generated by ground improvement. Blowing soil is a mixture of soil and solidifying material that blows up on the ground when the solidifying material is stirred in the ground.
Moreover, a convex part is formed in the surface layer of the said slope ground as needed, and the said convex part is connected to the top vicinity of the said slope parallel wall.

第1の発明では、斜面平行壁の施工間隔および斜面平行壁の壁厚を、地盤改良を行っていない未改良部の粘着力と地盤改良部の粘着力とから求められる複合地盤の粘着力を用いて算出した複合地盤の滑り安全率が1を超えるように設定することにより、斜面平行壁の壁面摩擦による拘束効果によって地盤の滑りを抑制することができる。また、斜面平行壁に加えて斜面直交壁を設けることにより、地震時の斜面平行壁の振動を抑制し、斜面地盤の液状化を抑制することができる。   In the first invention, the construction interval between the slope parallel walls and the wall thickness of the slope parallel walls are determined from the adhesive strength of the unimproved portion where the ground improvement is not performed and the adhesive strength of the composite ground obtained from the adhesive strength of the ground improved portion. By setting so that the slip safety factor of the composite ground calculated by using exceeds 1, the slip of the ground can be suppressed by the restraining effect due to the wall surface friction of the slope parallel wall. Moreover, by providing a slope orthogonal wall in addition to the slope parallel wall, vibration of the slope parallel wall during an earthquake can be suppressed and liquefaction of the slope ground can be suppressed.

第1の発明では、斜面平行壁の改良深度を過剰間隙水圧の抑制と斜面の滑り抑制に必要な深度までとしたり、斜面直交壁の改良深度を過剰間隙水圧抑制に必要な深度までとしたりすることにより、すべての格子壁を同一の深度に設定する従来の格子状改良の考え方に比べて改良土量を削減できる。また、斜面直交壁と斜面平行壁との交差部に杭を設置すれば、杭の曲げ抵抗によって格子状改良範囲全体の滑りをさらに抑制することができる。   In the first aspect of the invention, the improved depth of the inclined parallel wall is set to a depth necessary for suppressing excess pore water pressure and the slip of the inclined surface, or the improved depth of the orthogonal wall is set to a depth required for suppressing the excess pore water pressure. As a result, the amount of soil for improvement can be reduced as compared with the conventional idea of improving the lattice shape in which all the lattice walls are set to the same depth. Moreover, if a pile is installed in the cross | intersection part of a slope orthogonal wall and a slope parallel wall, the slip of the whole grid | lattice improvement range can further be suppressed by the bending resistance of a pile.

第1の発明において、地盤改良で発生する吹上土を用いて斜面地盤の表層を被覆する土被り部を設置すれば、土被り部による荷重増分による液状化抑制効果が得られるため、斜面平行壁の設置間隔を広げることができ、改良土量を削減することができる。また、斜面地盤の表層に形成した凸部を斜面平行壁の頂部近傍に接続すれば、地盤表層の土砂の流動を凸部で堰き止めることができる。   In the first aspect of the invention, if the earth covering part covering the surface layer of the slope ground is installed using the blown up soil generated by the ground improvement, the liquefaction suppression effect due to the load increment by the earth covering part can be obtained. The installation interval can be expanded, and the amount of improved soil can be reduced. Moreover, if the convex part formed in the surface layer of the slope ground is connected near the top part of the slope parallel wall, the flow of earth and sand on the ground surface can be blocked by the convex part.

第2の発明は、斜面地盤の流動を抑制する構造であって、斜面地盤に斜面と平行方向に所定の間隔で形成された地盤改良部である斜面平行壁を具備し、前記所定の間隔および前記斜面平行壁の壁厚は、地盤改良を行っていない未改良部の粘着力と前記地盤改良部の粘着力とから求められる複合地盤の粘着力を用いて算出した前記複合地盤の滑り安全率が1を超えるように設定され、前記斜面平行壁が、過剰間隙水圧抑制と斜面の滑り抑制に必要な深度まで形成され、前記斜面平行壁の壁面摩擦により前記斜面地盤の滑りが抑制されることを特徴とする斜面地盤の流動抑制構造である。過剰間隙水圧とは、液状化の原因である地震時に上昇する土中内の水圧である。   A second invention is a structure that suppresses the flow of slope ground, and includes slope parallel walls that are ground improvement portions formed at predetermined intervals in a direction parallel to the slope on the slope ground, The wall thickness of the slope parallel wall is the slip safety factor of the composite ground calculated by using the adhesive strength of the composite ground obtained from the adhesive strength of the unimproved portion not subjected to ground improvement and the adhesive strength of the ground improved portion. Is set to exceed 1, the slope parallel wall is formed to a depth necessary for suppressing excess pore water pressure and slope slip, and the slope ground slip is suppressed by wall friction of the slope parallel wall. It is a flow control structure of the slope ground characterized by Excess pore water pressure is the water pressure in the soil that rises during an earthquake that causes liquefaction.

第2の発明では、前記斜面平行壁が、平面視でジグザグ形状に形成される場合もある。
また、前記斜面地盤に前記斜面と略直交する方向に所定の間隔で形成された地盤改良部である斜面直交壁をさらに具備し、前記斜面直交壁は、過剰間隙水圧抑制に必要な深度だけ形成され、少なくとも一部の前記斜面直交壁の深度が、前記斜面平行壁の深度よりも浅く形成され、前記斜面直交壁により前記斜面地盤の液状化が抑制される場合もある。
In the second invention, the inclined parallel wall may be formed in a zigzag shape in plan view.
The slope ground further includes a slope orthogonal wall that is a ground improvement portion formed at a predetermined interval in a direction substantially orthogonal to the slope, and the slope orthogonal wall is formed to a depth necessary for suppressing excess pore water pressure. In some cases, the depth of at least a part of the orthogonal wall of the slope is formed to be shallower than the depth of the parallel wall of the slope, and the slope orthogonal wall suppresses liquefaction of the slope ground.

第2の発明では、斜面平行壁の施工間隔および斜面平行壁の壁厚を、地盤改良を行っていない未改良部の粘着力と地盤改良部の粘着力とから求められる複合地盤の粘着力を用いて算出した複合地盤の滑り安全率が1を超えるように設定することにより、斜面平行壁の壁面摩擦による拘束効果によって地盤の滑りを抑制することができる。また、斜面平行壁に加えて斜面平行壁の深度よりも浅い斜面直交壁を設けることにより、地震時の斜面平行壁の振動を抑制し、斜面地盤の液状化を抑制することができる。   In the second invention, the construction interval of the slope parallel walls and the wall thickness of the slope parallel walls are determined from the adhesive strength of the unimproved portion where the ground improvement is not performed and the adhesive strength of the composite ground obtained from the adhesive strength of the ground improved portion. By setting so that the slip safety factor of the composite ground calculated by using exceeds 1, the slip of the ground can be suppressed by the restraining effect due to the wall surface friction of the slope parallel wall. Further, by providing a slope orthogonal wall shallower than the depth of the slope parallel wall in addition to the slope parallel wall, vibration of the slope parallel wall during an earthquake can be suppressed and liquefaction of the slope ground can be suppressed.

第2の発明では、斜面平行壁の改良深度を過剰間隙水圧の抑制と斜面の滑り抑制に必要な深度までとしたり、斜面直交壁の改良深度を過剰間隙水圧抑制に必要な深度までとしたりすることにより、すべての格子壁を同一の深度に設定する従来の格子状改良の考え方に比べて改良土量を削減できる。   In the second invention, the improved depth of the parallel slope wall is set to a depth necessary for suppressing excess pore water pressure and the slip of the slope, or the improved depth of the orthogonal wall is set to a depth required for suppressing the excess pore water pressure. As a result, the amount of soil for improvement can be reduced as compared with the conventional idea of improving the lattice shape in which all the lattice walls are set to the same depth.

本発明によれば、少ない改良土量で地盤を広範囲にわたって適切に改良し、斜面地盤の安定性を高めることができる斜面地盤の流動抑制方法および構造を提供できる。   ADVANTAGE OF THE INVENTION According to this invention, the ground suppression method and structure which can improve the ground appropriately over a wide range with a small improvement soil amount, and can improve the stability of a slope ground can be provided.

斜面地盤2および流動抑制構造1の概要を示す図The figure which shows the outline of the slope ground 2 and the flow suppression structure 1 斜面地盤27および流動抑制構造31の概要を示す図The figure which shows the outline | summary of the slope ground 27 and the flow suppression structure 31 斜面地盤27に施工された流動抑制構造31の概要を示す図The figure which shows the outline | summary of the flow suppression structure 31 constructed in the slope ground 27 他の流動抑制構造を示す図Diagram showing another flow suppression structure 流動抑制構造31cの概要を示す図The figure which shows the outline | summary of the flow suppression structure 31c 流動抑制構造31dの概要を示す図The figure which shows the outline | summary of the flow suppression structure 31d 流動抑制構造31eの概要を示す図The figure which shows the outline | summary of the flow suppression structure 31e 他の流動抑制構造の概要を示す図Diagram showing the outline of another flow control structure 斜面平行壁を平面視でジグザグ状に形成した例を示す図The figure which shows the example which formed the slope parallel wall in zigzag shape by plane view

以下図面に基づいて、本発明の第1の実施の形態を詳細に説明する。図1は、斜面地盤2および流動抑制構造1の概要を示す図である。図1(a)は、斜面地盤2の斜面方向の縦断図、図1(b)は、図1(a)に示す範囲Aに流動抑制構造1による対策を施した場合の斜視図、図1(c)は、図1(b)に示すユニット13の斜面直交方向の断面図、図1(d)は、図1(a)に示す範囲Aの拡大図である。図1(a)、図1(d)は、図の右側が滑り層3の滑り方向の上流側、図の左側が下流側である。図1(b)は、図の奥側が滑り層3の滑り方向の上流側、図の手前側が下流側である。   Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of the slope ground 2 and the flow suppressing structure 1. FIG. 1A is a longitudinal sectional view of the slope ground 2 in the slope direction, FIG. 1B is a perspective view in the case where measures are taken by the flow suppressing structure 1 in the range A shown in FIG. (C) is sectional drawing of the unit 13 shown in FIG.1 (b) in the orthogonal direction of a slope, FIG.1 (d) is an enlarged view of the range A shown to Fig.1 (a). 1A and 1D, the right side of the figure is the upstream side in the sliding direction of the sliding layer 3, and the left side of the figure is the downstream side. In FIG. 1B, the far side in the figure is the upstream side in the sliding direction of the sliding layer 3, and the near side in the figure is the downstream side.

図1に示すように、斜面地盤2は、基礎地盤4と滑り層3とからなる。斜面地盤2では、豪雨時の斜面15の崩壊対策として、図1(b)に示すように、滑り層3に流動抑制構造1を形成する。   As shown in FIG. 1, the slope ground 2 includes a foundation ground 4 and a sliding layer 3. In the slope ground 2, as shown in FIG.1 (b), the flow suppression structure 1 is formed in the sliding layer 3 as a countermeasure against the collapse of the slope 15 during heavy rain.

図1(b)に示すように、流動抑制構造1は、所定の間隔7をおいて設けられた複数の斜面平行壁5からなる。斜面平行壁5は、斜面地盤2の斜面15と平行方向に、すなわち、滑り層3の流動方向の上流側から下流側に沿った方向に配置される。   As shown in FIG. 1B, the flow suppressing structure 1 is composed of a plurality of inclined parallel walls 5 provided at a predetermined interval 7. The slope parallel wall 5 is arranged in a direction parallel to the slope 15 of the slope ground 2, that is, in a direction along the downstream side from the upstream side in the flow direction of the sliding layer 3.

流動抑制構造1を形成するには、滑り層3を斜面地盤2の斜面15と平行方向に地盤改良して、地盤改良部である複数の斜面平行壁5を施工する。斜面平行壁5の間隔7および斜面平行壁5の壁厚9は、地盤改良を行っていない未改良部の粘着力Cs’と地盤改良部である斜面平行壁5の粘着力Cc’とから求められる複合地盤の粘着力C’を用いて複合地盤の滑り安全率を算出し、滑り安全率が1を超えるように設定される。   In order to form the flow suppression structure 1, the sliding layer 3 is ground improved in a direction parallel to the slope 15 of the slope ground 2, and a plurality of slope parallel walls 5 that are ground improvement portions are constructed. The interval 7 of the slope parallel walls 5 and the wall thickness 9 of the slope parallel walls 5 are obtained from the adhesive force Cs ′ of the unimproved portion where the ground improvement is not performed and the adhesive force Cc ′ of the slope parallel wall 5 which is the ground improved portion. The slip safety factor of the composite ground is calculated using the adhesive strength C ′ of the composite ground, and the slip safety factor is set to exceed 1.

斜面地盤2から図1(b)に示すユニット13を取り出すと、ユニット13の斜面直交方向の断面は、図1(c)に示すようになる。ユニット13は、未改良部と地盤改良部である斜面平行壁5からなる複合地盤である。1つのユニット13に占める斜面平行壁5の率aは、壁厚9をB、間隔7をLとすると、a=B/Lとなる。1つのユニット13は、一部が地盤改良部である斜面平行壁5に置き換わっているため、円弧滑りに対する抵抗力が増している。これを粘着力Cs’の未改良部と粘着力Cc’の地盤改良部である斜面平行壁5からなる複合地盤の粘着力として評価すれば、複合地盤の粘着力C’は数式(1)により表される。   When the unit 13 shown in FIG. 1 (b) is taken out from the slope ground 2, the cross section of the unit 13 in the direction perpendicular to the slope becomes as shown in FIG. 1 (c). The unit 13 is a composite ground composed of an unimproved portion and a slope parallel wall 5 which is a ground improved portion. The rate a of the inclined parallel wall 5 occupying one unit 13 is a = B / L, where B is the wall thickness 9 and L is the interval 7. Since one unit 13 is replaced by the inclined parallel wall 5 which is a ground improvement part, the resistance against arc slip is increased. If this is evaluated as the adhesive strength of the composite ground consisting of the unimproved portion of the adhesive strength Cs ′ and the slope parallel wall 5 which is the ground improved portion of the adhesive strength Cc ′, the adhesive strength C ′ of the composite ground is expressed by Equation (1). expressed.

C’=aCc’+(1−a)Cs’・・・(1)   C '= aCc' + (1-a) Cs' (1)

また、図1(d)に示すように、滑り円弧11内の土塊を複数の分割土塊17−1、17−2、…、17−nに分割すると、複合地盤の滑り安全率Fsは、複合地盤の粘着力C’、せん断強さτ’、分割土塊17の滑り辺の長さl、分割土塊17の重量W、間隙水圧u、分割土塊17の幅b、各分割土塊17の滑り辺の中点と滑り円の中心とを結ぶ直線と鉛直線とのなす角α、せん断抵抗各φ’を用いて、数式(2)により表される。   Further, as shown in FIG. 1D, when the soil block in the sliding arc 11 is divided into a plurality of divided soil blocks 17-1, 17-2,. Adhesion C ′ of the ground, shear strength τ ′, length l of the sliding side of the divided soil block 17, weight W of the divided soil block 17, pore water pressure u, width b of the divided soil block 17, and the sliding side of each divided soil block 17 The angle α formed by the straight line connecting the midpoint and the center of the sliding circle and the vertical line, and each shearing resistance φ ′ are expressed by Equation (2).

Fs=Στ’/ΣWsinα=Σ{C’・l+(W−ub)cosα・tanφ’}/ΣWsinα・・・(2)   Fs = Στ ′ / ΣWsin α = Σ {C ′ · l + (W−ub) cos α · tan φ ′} / ΣWsin α (2)

斜面平行壁5の間隔7および斜面平行壁5の壁厚9を決定する際には、壁厚9をB、間隔7をLとしてB、Lを仮決定し、数式1から複合地盤の粘着力C’を求める。そして、複合地盤の粘着力C’を数式2に代入してFs>1となるか否かを確認する。Fsに余裕があれば、B、Lを小さくして再計算を行い、合理的なB、Lを決定する。   When determining the interval 7 of the inclined parallel walls 5 and the wall thickness 9 of the inclined parallel walls 5, the wall thickness 9 is B, the interval 7 is L, and B and L are temporarily determined. Find C '. Then, by substituting the adhesive force C ′ of the composite ground into Equation 2, it is confirmed whether or not Fs> 1. If there is a margin in Fs, B and L are reduced and recalculation is performed to determine rational B and L.

斜面平行壁5の深度は、滑り層3の過剰間隙水圧の抑制と滑りの抑制とを考慮して決定される。過剰間隙水圧とは、液状化の原因である地震時に上昇する土中内の水圧である。斜面平行壁5の深度は、滑り層3の滑りを抑制するため、基礎地盤4に着底する程度とするか、基礎地盤4に根入れするのが望ましいが、上述した安定計算で得た滑り円弧11が浅い場合は非着底型にできる。   The depth of the inclined parallel wall 5 is determined in consideration of suppression of excess pore water pressure of the sliding layer 3 and suppression of slippage. Excess pore water pressure is the water pressure in the soil that rises during an earthquake that causes liquefaction. The depth of the slope parallel wall 5 is preferably set to the bottom of the foundation ground 4 or to be embedded in the foundation ground 4 in order to suppress the sliding of the sliding layer 3, but the slip obtained by the above-described stability calculation is preferable. When the arc 11 is shallow, it can be a non-bottomed type.

なお、地盤改良の工法には、例えば、パワーブレンダー(登録商標)工法などの中層混合処理工法で改良深度を任意に設定できる工法が望ましい。   In addition, as the ground improvement method, for example, a method in which the improvement depth can be arbitrarily set by a middle layer mixing method such as a power blender (registered trademark) method is desirable.

第1の実施の形態では、斜面地盤2に斜面平行壁5を施工して流動抑制構造1を形成することにより、斜面平行壁5の壁面摩擦により豪雨時に滑り層3の滑りを抑制し、斜面地盤2の安定性を高めることができる。   In the first embodiment, the slope parallel wall 5 is constructed on the slope ground 2 to form the flow restraining structure 1, thereby suppressing the slip of the sliding layer 3 during heavy rain due to the wall friction of the slope parallel wall 5. The stability of the ground 2 can be enhanced.

次に、第2の実施の形態について説明する。図2は、斜面地盤27および流動抑制構造31の概要を示す図である。図2(a)は、鉱さい集積場19の斜面方向の縦断図である。図2(a)では、図の右側が軟弱層23の流動方向の上流側、図の左側が下流側である。図2(b)は、図2(a)に示す範囲Bに流動抑制構造31による対策を施した場合の斜視図であり、軟弱層23を省略して図示している。図2(b)では、図の奥側が流動方向の上流側、図の手前側が下流側である。   Next, a second embodiment will be described. FIG. 2 is a diagram showing an outline of the slope ground 27 and the flow suppressing structure 31. FIG. 2A is a longitudinal sectional view of the slag accumulation site 19 in the slope direction. 2A, the right side of the figure is the upstream side in the flow direction of the soft layer 23, and the left side of the figure is the downstream side. FIG. 2B is a perspective view when the countermeasure by the flow suppressing structure 31 is applied to the range B shown in FIG. 2A, and the soft layer 23 is omitted. In FIG. 2B, the far side in the figure is the upstream side in the flow direction, and the near side in the figure is the downstream side.

図3は、斜面地盤27に施工された流動抑制構造31の概要を示す図である。図3(a)は、斜面地盤27の平面図である図3(b)に示す矢印C−Cによる斜面地盤27の斜面直交方向の縦断図である。図3(a)では、図の奥側が軟弱層23の流動方向の上流側、図の手前側が下流側である。図3(b)は、流動抑制構造31を施工した斜面地盤27の平面図である。   FIG. 3 is a diagram showing an outline of the flow suppression structure 31 constructed on the slope ground 27. FIG. 3A is a longitudinal sectional view of the slope ground 27 in the direction orthogonal to the slope according to the arrow CC shown in FIG. 3B, which is a plan view of the slope ground 27. In FIG. 3A, the far side in the figure is the upstream side in the flow direction of the soft layer 23, and the near side in the figure is the downstream side. FIG. 3B is a plan view of the slope ground 27 on which the flow suppressing structure 31 is constructed.

図2(a)に示すように、鉱さい集積場19では、斜面地盤27の非液状化層21の底部に基礎堤25が設けられ、基礎堤25の上流側に集積物を集積した軟弱層23が形成される。基礎堤25の上流側の軟弱層23上には、かん止堤29による築堤がなされる場合がある。鉱さい集積場19の耐震補強として、斜面地盤27の軟弱層23に、図2(b)に示すように、液状化による流動を抑制するための流動抑制構造31を形成する。   As shown in FIG. 2 (a), in the mine accumulation site 19, a foundation dam 25 is provided at the bottom of the non-liquefied layer 21 of the slope ground 27, and a soft layer 23 in which accumulations are accumulated upstream of the foundation dam 25. Is formed. On the soft layer 23 on the upstream side of the foundation levee 25, there is a case where a levee with a dam 29 is built. As the seismic reinforcement of the mine accumulation site 19, a flow suppressing structure 31 for suppressing a flow due to liquefaction is formed in the soft layer 23 of the slope ground 27 as shown in FIG.

図2(b)、図3に示すように、流動抑制構造31は、所定の間隔37をおいて施工された複数の斜面平行壁33、所定の間隔39をおいて施工された複数の斜面直交壁35からなる。斜面平行壁33は、斜面地盤27の斜面と平行方向に、すなわち、軟弱層23の流動方向の上流側から下流側に沿った方向に配置される。斜面直交壁35は、斜面地盤2の斜面と略直交する方向に、すなわち、軟弱層23の流動方向と直交する方向に配置される。   As shown in FIG. 2B and FIG. 3, the flow suppressing structure 31 includes a plurality of slope parallel walls 33 constructed at a predetermined interval 37 and a plurality of slope orthogonal members constructed at a predetermined interval 39. It consists of a wall 35. The slope parallel wall 33 is arranged in a direction parallel to the slope of the slope ground 27, that is, in a direction from the upstream side to the downstream side in the flow direction of the soft layer 23. The slope orthogonal wall 35 is disposed in a direction substantially perpendicular to the slope of the slope ground 2, that is, in a direction perpendicular to the flow direction of the soft layer 23.

流動抑制構造31を形成するには、まず、軟弱層23を斜面地盤27の斜面と平行する方向に地盤改良して、複数の斜面平行壁33を施工する。斜面平行壁33の施工間隔や壁厚は、第1の実施の形態と同様に、地盤改良を行っていない未改良部の粘着力Cs’と地盤改良部である斜面平行壁33の粘着力Cc’とから求められる複合地盤の粘着力C’を用いて複合地盤の滑り安全率を算出し、滑り安全率が1を超えるように設定される。   In order to form the flow suppression structure 31, first, the soft layer 23 is ground improved in a direction parallel to the slope of the slope ground 27, and a plurality of slope parallel walls 33 are constructed. As in the first embodiment, the construction interval and wall thickness of the slope parallel wall 33 are the adhesive force Cs ′ of the unimproved portion where the ground improvement is not performed and the adhesive force Cc of the slope parallel wall 33 which is the ground improvement portion. The slip safety factor of the composite ground is calculated by using the adhesive strength C of the composite ground obtained from “,” and the slip safety factor is set to exceed 1.

斜面平行壁33の深度43は、軟弱層23の過剰間隙水圧の抑制と滑りの抑制とを考慮して決定される。斜面平行壁33の深度43は、軟弱層23の滑りを抑制するため、非液状化層21に着底する程度とするか、非液状化層21に根入れするのが望ましいが、安定計算で得た滑り円弧が浅い場合は非着底型にできる。   The depth 43 of the inclined parallel wall 33 is determined in consideration of suppression of excess pore water pressure and suppression of slippage of the soft layer 23. The depth 43 of the inclined parallel wall 33 is preferably set to the bottom of the non-liquefied layer 21 or is embedded in the non-liquefied layer 21 in order to suppress the slip of the soft layer 23. When the obtained sliding arc is shallow, it can be made non-bottomed.

斜面平行壁33を施工した後、軟弱層23を斜面地盤27の斜面と略直交方向に地盤改良して、複数の斜面直交壁35を施工する。斜面直交壁35の深度45は、軟弱層23の過剰間隙水圧の抑制のみを考慮して決定される。斜面直交壁35は、斜面平行壁33に接合している必要はない。   After the slope parallel wall 33 is constructed, the soft layer 23 is ground improved in a direction substantially perpendicular to the slope of the slope ground 27, and a plurality of slope orthogonal walls 35 are constructed. The depth 45 of the slope orthogonal wall 35 is determined considering only suppression of excess pore water pressure of the soft layer 23. The slope orthogonal wall 35 does not need to be joined to the slope parallel wall 33.

地盤改良の工法には、例えば、パワーブレンダー(登録商標)工法などの中層混合処理工法で改良深度を任意に設定できる工法が望ましい。   As the ground improvement method, for example, a method in which the improvement depth can be arbitrarily set by a middle-layer mixing method such as Power Blender (registered trademark) method is desirable.

第2の実施の形態では、斜面地盤27に斜面平行壁33と斜面直交壁35とからなる流動抑制構造31を形成することにより、地震時に液状化しやすい軟弱層23の表層の過剰間隙水圧を抑制して斜面地盤27の表面の揺れを防止することができる。また、斜面平行壁33の壁面摩擦により斜面地盤27の軟弱層23の滑りを抑制し、斜面直交壁35で斜面平行壁33の振動を抑制して、斜面地盤27の安定性を高めることができる。第2の実施の形態では、斜面直交壁35の深度45を過剰間隙水圧の抑制のみを考慮して決定することにより、広範囲にわたって地盤改良を行う場合にも、改良土量を削減できる。   In the second embodiment, by forming the flow suppressing structure 31 including the inclined parallel wall 33 and the inclined orthogonal wall 35 on the inclined ground 27, the excess pore water pressure in the surface layer of the soft layer 23 that is liable to be liquefied during an earthquake is suppressed. As a result, the surface of the slope ground 27 can be prevented from shaking. Further, the slip of the soft layer 23 of the slope ground 27 can be suppressed by the wall friction of the slope parallel wall 33, and the vibration of the slope parallel wall 33 can be suppressed by the slope orthogonal wall 35, so that the stability of the slope ground 27 can be enhanced. . In the second embodiment, by determining the depth 45 of the inclined orthogonal wall 35 in consideration of only suppression of excess pore water pressure, the amount of improved soil can be reduced even when performing ground improvement over a wide range.

図4は、他の流動抑制構造を示す図である。図4(a)は、流動抑制構造31aが形成された斜面地盤27の斜面直交方向の縦断図を示す。図4(a)では、図の奥側が軟弱層23の流動方向の上流側、図の手前側が下流側である。第2の実施の形態の流動抑制構造31では、全ての斜面平行壁33を非液状化層21に着底する程度の深度としたが、斜面平行壁33の深度はこの限りでない。軟弱層23の過剰間隙水圧を抑制するとともに、斜面平行壁33を施工する際、固化材の添加量を増やして斜面平行壁33のせん断強度を高め、滑りを抑制することができれば、図4(a)に示すように、一部の斜面平行壁33aの深度を他の斜面平行壁33の深度よりも浅くすることができる(最浅で斜面直交壁35の深度と同程度としてもよい)。   FIG. 4 is a diagram showing another flow suppressing structure. Fig.4 (a) shows the longitudinal cross-sectional view of the slope orthogonal direction of the slope ground 27 in which the flow suppression structure 31a was formed. In FIG. 4A, the far side in the figure is the upstream side in the flow direction of the soft layer 23, and the near side in the figure is the downstream side. In the flow suppressing structure 31 according to the second embodiment, the depth is such that all the inclined parallel walls 33 settle to the non-liquefied layer 21, but the depth of the inclined parallel walls 33 is not limited to this. If the excess pore water pressure of the soft layer 23 is suppressed, and the slope parallel wall 33 is constructed, the amount of solidification material added can be increased to increase the shear strength of the slope parallel wall 33, thereby suppressing slippage. As shown to a), the depth of some slope parallel walls 33a can be made shallower than the depth of other slope parallel walls 33 (the depth may be the same as the depth of the slope orthogonal wall 35 at the shallowest).

図4(b)は、流動抑制構造31bが形成された斜面地盤27の平面図を示す。第2の実施の形態の流動抑制構造31では、斜面平行壁33を形成した後に斜面直交壁35を形成したが、図4(b)に示す流動抑制構造31bのように、斜面平行壁33bと斜面直交壁35bとを一体に形成してもよい。また、斜面平行壁33bと斜面直交壁35bとが形成する隅角部にハンチ的な補強部分41を形成してもよい。   FIG.4 (b) shows the top view of the slope ground 27 in which the flow suppression structure 31b was formed. In the flow restraint structure 31 of the second embodiment, the slope orthogonal wall 35 is formed after the slope parallel wall 33 is formed. However, like the flow restraint structure 31b shown in FIG. The slope orthogonal wall 35b may be integrally formed. Moreover, you may form the haunch-like reinforcement part 41 in the corner | angular part which the slope parallel wall 33b and the slope orthogonal wall 35b form.

次に、第3の実施の形態について説明する。図5は、第3の実施の形態の流動抑制構造31cの概要を示す図である。図5(a)は、流動抑制構造31cが形成された斜面地盤27の斜面直交方向の縦断図を示す。図5(a)では、図の奥側が軟弱層23の流動方向の上流側、図の手前側が下流側である。図5(b)は、斜面平行壁33cの設置間隔37cと土被り部47の厚さ49の最適化を行うためのフローチャートを示す。   Next, a third embodiment will be described. FIG. 5 is a diagram showing an outline of the flow suppressing structure 31c of the third embodiment. Fig.5 (a) shows the longitudinal cross-sectional view of the slope orthogonal direction of the slope ground 27 in which the flow suppression structure 31c was formed. In FIG. 5A, the far side in the figure is the upstream side in the flow direction of the soft layer 23, and the near side in the figure is the downstream side. FIG. 5B shows a flowchart for optimizing the installation interval 37 c of the inclined parallel wall 33 c and the thickness 49 of the covering portion 47.

斜面地盤27に流動抑制構造31cを形成するには、図5(a)に示すように、まず、斜面と平行方向に地盤改良を行って複数の斜面平行壁33cを施工する。斜面平行壁33cの施工間隔や壁厚は、第1の実施の形態と同様に、地盤改良を行っていない未改良部の粘着力Cs’と地盤改良部である斜面平行壁33cの粘着力Cc’とから求められる複合地盤の粘着力C’を用いて複合地盤の滑り安全率を算出し、滑り安全率が1を超えるように設定される。   In order to form the flow restraining structure 31c on the slope ground 27, as shown in FIG. 5A, first, ground improvement is performed in a direction parallel to the slope to construct a plurality of slope parallel walls 33c. As in the first embodiment, the construction interval and wall thickness of the slope parallel wall 33c are the same as in the first embodiment, but the adhesive force Cs ′ of the unimproved portion where the ground improvement is not performed and the adhesive force Cc of the slope parallel wall 33c which is the ground improvement portion. The slip safety factor of the composite ground is calculated by using the adhesive strength C of the composite ground obtained from “,” and the slip safety factor is set to exceed 1.

斜面平行壁33cの深度は、軟弱層23の過剰間隙水圧の抑制と滑りの抑制とを考慮して決定される。斜面平行壁33cの深度は、軟弱層23の滑りを抑制するため、非液状化層21に着底する程度とするか、非液状化層21に根入れするのが望ましいが、安定計算で得た滑り円弧が浅い場合は非着底型にできる。   The depth of the inclined parallel wall 33c is determined in consideration of the suppression of excess pore water pressure and the suppression of slippage of the soft layer 23. It is desirable that the depth of the inclined parallel wall 33c be set to the bottom of the non-liquefied layer 21 or to be embedded in the non-liquefied layer 21 in order to suppress the slip of the soft layer 23, but obtained by stable calculation. If the sliding arc is shallow, it can be made non-bottomed.

次に、斜面と略直交する方向に地盤改良を行って複数の斜面直交壁35cを施工する。斜面直交壁35cの深度は、軟弱層23の過剰間隙水圧の抑制のみを考慮して決定される。   Next, the ground is improved in a direction substantially orthogonal to the slope, and a plurality of slope orthogonal walls 35c are constructed. The depth of the slope orthogonal wall 35c is determined considering only suppression of excess pore water pressure of the soft layer 23.

斜面直交壁35cを施工した後、斜面平行壁33cや斜面直交壁35cを施工する際に地盤改良で発生する吹上土を用いて、斜面地盤27の表層を被覆する土被り部47を設置する。土被り部47を設置する際には、吹上土をそのまま用いてもよいし、硬化した吹上土を粉砕してセメント等を加えて用いてもよい。吹上土をそのまま用いる場合、土被り部47を転圧して改良してもよい。転圧したりセメント等を加えたりして形成した土被り部47は、重機の作業足場として使用可能である。   After the slope orthogonal wall 35c is constructed, the earth covering portion 47 that covers the surface layer of the slope ground 27 is installed using the blowing soil generated by the ground improvement when constructing the slope parallel wall 33c and the slope orthogonal wall 35c. When installing the earth covering portion 47, the blown-up soil may be used as it is, or the hardened blown-up soil may be crushed and added with cement or the like. When using the blown up soil as it is, the earth covering portion 47 may be rolled and improved. The earth covering portion 47 formed by rolling or adding cement or the like can be used as a working scaffold for heavy machinery.

流動抑制構造31cを形成する際には、図5(b)に示すフローチャートにしたがって、斜面平行壁33cの設置間隔37cと土被り部47の厚さ49の最適化を行う。最適化を行うには、まず、斜面平行壁33cの設置間隔37cを設定し(ステップ101)、軟弱層23の液状化判定を行う(ステップ103)。ステップ103で液状化すると判定された場合は、ステップ101に戻る。   When the flow suppressing structure 31c is formed, the installation interval 37c of the inclined parallel wall 33c and the thickness 49 of the covering portion 47 are optimized according to the flowchart shown in FIG. In order to optimize, first, the installation interval 37c of the inclined parallel wall 33c is set (step 101), and the liquefaction determination of the soft layer 23 is performed (step 103). If it is determined in step 103 that the liquid is liquefied, the process returns to step 101.

ステップ103で液状化しないと判定された場合は、地盤改良で発生する吹上土の量を算出し(ステップ105)、土被り部47の厚さ49を設定し(ステップ107)、軟弱層23の液状化判定を行う(ステップ109)。ステップ109で軟弱層23の強度に余裕があると判定された場合は、斜面平行壁33cの設置間隔37cを再設定し(ステップ111)、ステップ105に戻る。ステップ109で余裕がないと判定された場合は、最も合理的な斜面平行壁33cの設置間隔37cおよび土被り部47の厚さ49が得られたと判断し、最適化を終了する。   If it is determined in step 103 that the soil is not liquefied, the amount of blowing soil generated by the ground improvement is calculated (step 105), the thickness 49 of the covering portion 47 is set (step 107), and the soft layer 23 Liquefaction determination is performed (step 109). If it is determined in step 109 that the soft layer 23 has sufficient strength, the installation interval 37c of the inclined parallel wall 33c is reset (step 111), and the process returns to step 105. If it is determined in step 109 that there is no allowance, it is determined that the most reasonable installation interval 37c of the inclined parallel wall 33c and the thickness 49 of the covering portion 47 have been obtained, and the optimization ends.

第3の実施の形態では、斜面地盤27に斜面平行壁33cと斜面直交壁35cとを有する流動抑制構造31cを形成した上で、斜面地盤27の表層に土被り部47を設置することにより、地震時に液状化しやすい軟弱層23の表層の過剰間隙水圧を抑制して斜面地盤27の表面の揺れを防止することができる。また、斜面平行壁33cの壁面摩擦により斜面地盤27の軟弱層23の滑りを抑制し、斜面直交壁35cで斜面平行壁33cの振動を抑制して、斜面地盤27の安定性を高めることができる。   In the third embodiment, by forming the flow suppression structure 31c having the slope parallel wall 33c and the slope orthogonal wall 35c on the slope ground 27, and installing the earth covering portion 47 on the surface layer of the slope ground 27, It is possible to prevent the surface of the slope ground 27 from shaking by suppressing the excessive pore water pressure in the surface layer of the soft layer 23 that is easily liquefied during an earthquake. Moreover, the slip of the soft layer 23 of the slope ground 27 can be suppressed by the wall friction of the slope parallel wall 33c, and the vibration of the slope parallel wall 33c can be suppressed by the slope orthogonal wall 35c, thereby improving the stability of the slope ground 27. .

第3の実施の形態では、土被り部47による液状化抵抗性の増大によって格子壁の設置間隔をさらに広げることが可能になる。第3の実施の形態では、図5(b)に示すフローチャートにより斜面平行壁33cの設置間隔37cおよび土被り部47の厚さ49の最適化を行うことにより、斜面平行壁33cの設置間隔37cを拡げ、改良土量を削減できる。   In the third embodiment, the increase in liquefaction resistance by the earth covering portion 47 can further increase the interval between the lattice walls. In the third embodiment, the installation interval 37c of the inclined parallel walls 33c is optimized by optimizing the installation interval 37c of the inclined parallel walls 33c and the thickness 49 of the soil covering portion 47 according to the flowchart shown in FIG. Can be expanded and the amount of improved soil can be reduced.

次に、第4の実施の形態について説明する。図6は、第4の実施の形態の流動抑制構造31dの概要を示す図である。図6(a)は、斜面地盤27の平面図である図6(b)に示す矢印D−Dによる斜面地盤27の斜面直交方向の縦断図である。図6(a)は、図の奥側が軟弱層23の流動方向の上流側、図の手前側が下流側である。図6(b)は、流動抑制構造31dを施工した斜面地盤27の平面図である。   Next, a fourth embodiment will be described. FIG. 6 is a diagram illustrating an outline of a flow suppressing structure 31d according to the fourth embodiment. FIG. 6A is a longitudinal sectional view of the slope ground 27 in the direction orthogonal to the slope according to the arrow DD shown in FIG. 6B, which is a plan view of the slope ground 27. In FIG. 6A, the far side in the figure is the upstream side in the flow direction of the soft layer 23, and the near side in the figure is the downstream side. FIG.6 (b) is a top view of the slope ground 27 which constructed the flow suppression structure 31d.

斜面地盤27に流動抑制構造31dを形成するには、図6に示すように、まず、斜面と平行方向に地盤改良を行って複数の斜面平行壁33dを施工する。斜面平行壁33dの施工間隔や壁厚は、第1の実施の形態と同様に、地盤改良を行っていない未改良部の粘着力Cs’と地盤改良部である斜面平行壁33dの粘着力Cc’とから求められる複合地盤の粘着力C’を用いて複合地盤の滑り安全率を算出し、滑り安全率が1を超えるように設定される。斜面平行壁33dの深度は、軟弱層23の過剰間隙水圧の抑制と滑りの抑制とを考慮して決定される。   In order to form the flow restraining structure 31d on the slope ground 27, as shown in FIG. 6, first, ground improvement is performed in a direction parallel to the slope to construct a plurality of slope parallel walls 33d. As in the first embodiment, the construction interval and wall thickness of the slope parallel wall 33d are the adhesive force Cs ′ of the unimproved portion where the ground improvement is not performed and the adhesive force Cc of the slope parallel wall 33d which is the ground improvement portion. The slip safety factor of the composite ground is calculated by using the adhesive strength C of the composite ground obtained from “,” and the slip safety factor is set to exceed 1. The depth of the inclined parallel wall 33d is determined in consideration of the suppression of excess pore water pressure and the suppression of slip of the soft layer 23.

次に、斜面と略直交する方向に地盤改良を行って複数の斜面直交壁35dを施工する。斜面直交壁35dの深度は、軟弱層23の過剰間隙水圧の抑制のみを考慮して決定される。   Next, the ground is improved in a direction substantially orthogonal to the slope, and a plurality of slope orthogonal walls 35d are constructed. The depth of the inclined wall 35d is determined considering only suppression of excess pore water pressure of the soft layer 23.

その後、斜面平行壁33dと斜面直交壁35dとの交差部に杭51を設置する。杭51の仕様は、軟弱層23の滑りを抑制できるものとする。斜面平行壁33dおよび杭51の深さは、例えば、非液状化層21に着底する程度とするか、非液状化層21に根入れするのが望ましいが、安定計算で得た滑り円弧が浅い場合は非着底型にできる。   Then, the pile 51 is installed in the crossing part of the slope parallel wall 33d and the slope orthogonal wall 35d. The specification of the pile 51 shall suppress the slip of the soft layer 23. FIG. For example, the depth of the inclined parallel wall 33d and the pile 51 is preferably set to be settled on the non-liquefied layer 21 or embedded in the non-liquefied layer 21. If it is shallow, it can be non-bottomed.

第4の実施の形態では、斜面地盤27に斜面平行壁33dと斜面直交壁35dとを有する流動抑制構造31dを形成することにより、地震時に液状化しやすい軟弱層23の表層の過剰間隙水圧を抑制して斜面地盤27の表面の揺れを防止することができる。また、斜面平行壁33dの壁面摩擦や杭51により斜面地盤27の軟弱層23の滑りを抑制し、斜面直交壁35dで斜面平行壁33dの振動を抑制して、斜面地盤27の安定性を高めることができる。   In the fourth embodiment, by forming the flow suppressing structure 31d having the inclined parallel wall 33d and the inclined orthogonal wall 35d on the inclined ground 27, the excess pore water pressure on the surface of the soft layer 23 that is liable to be liquefied during an earthquake is suppressed. As a result, the surface of the slope ground 27 can be prevented from shaking. Further, the wall surface friction of the slope parallel wall 33d and the pile 51 suppress the slip of the soft layer 23 of the slope ground 27, and the slope orthogonal wall 35d suppresses the vibration of the slope parallel wall 33d to enhance the stability of the slope ground 27. be able to.

第4の実施の形態では、斜面平行壁33dや斜面直交壁35dの深度を過剰間隙水圧の抑制のみを考慮して決定することにより、広範囲にわたって地盤改良を行う場合にも、改良土量を削減できる。   In the fourth embodiment, the depth of the slope parallel wall 33d and the slope orthogonal wall 35d is determined in consideration of only suppression of excess pore water pressure, thereby reducing the amount of improved soil even when performing ground improvement over a wide range. it can.

次に、第5の実施の形態について説明する。図7は、第5の実施の形態の流動抑制構造31eの概要を示す図である。図7(a)は、斜面地盤27の平面図である図7(c)に示す矢印E−Eによる斜面地盤27の斜面直交方向の縦断図である。図7(a)では、図の奥側が軟弱層23の流動方向の上流側、図の手前側が下流側である。図7(b)は、図7(c)に示す矢印F−Fによる斜面地盤27の斜面方向の縦断図である。図7(b)では、図の右側が軟弱層23の流動方向の上流側、図の左側が下流側である。図7(c)は、流動抑制構造31eを施工した斜面地盤27の平面図である。   Next, a fifth embodiment will be described. FIG. 7 is a diagram showing an outline of the flow suppressing structure 31e of the fifth embodiment. FIG. 7A is a longitudinal sectional view of the slope ground 27 in the direction orthogonal to the slope taken along arrows EE shown in FIG. 7C, which is a plan view of the slope ground 27. In Fig.7 (a), the back side of a figure is an upstream of the flow direction of the soft layer 23, and the near side of a figure is a downstream. FIG.7 (b) is a longitudinal cross-sectional view of the slope direction of the slope ground 27 by the arrow FF shown in FIG.7 (c). In FIG. 7B, the right side of the figure is the upstream side in the flow direction of the soft layer 23, and the left side of the figure is the downstream side. FIG.7 (c) is a top view of the slope ground 27 which constructed the flow suppression structure 31e.

斜面地盤27に流動抑制構造31eを形成するには、図7に示すように、まず、斜面と平行方向に地盤改良を行って複数の斜面平行壁33eを施工する。斜面平行壁33eの施工間隔や壁厚は、第1の実施の形態と同様に、地盤改良を行っていない未改良部の粘着力Cs’と地盤改良部である斜面平行壁33eの粘着力Cc’とから求められる複合地盤の粘着力C’を用いて複合地盤の滑り安全率を算出し、滑り安全率が1を超えるように設定される。   In order to form the flow suppression structure 31e on the slope ground 27, as shown in FIG. 7, first, ground improvement is performed in a direction parallel to the slope, and a plurality of slope parallel walls 33e are constructed. As in the first embodiment, the construction interval and wall thickness of the slope parallel wall 33e are the adhesive force Cs ′ of the unimproved portion where the ground improvement is not performed and the adhesive force Cc of the slope parallel wall 33e which is the ground improvement portion. The slip safety factor of the composite ground is calculated by using the adhesive strength C of the composite ground obtained from “,” and the slip safety factor is set to exceed 1.

斜面平行壁33eの深度は、軟弱層23の過剰間隙水圧の抑制と滑りの抑制とを考慮して決定される。斜面平行壁33eの深度は、軟弱層23の滑りを抑制するため、非液状化層21に着底する程度とするか、非液状化層21に根入れするのが望ましいが、安定計算で得た滑り円弧が浅い場合は非着底型にできる。   The depth of the inclined parallel wall 33e is determined in consideration of the suppression of excess pore water pressure and the suppression of slippage of the soft layer 23. The depth of the inclined parallel wall 33e is preferably set to the bottom of the non-liquefied layer 21 or is embedded in the non-liquefied layer 21 in order to suppress the slip of the soft layer 23, but is obtained by stable calculation. If the sliding arc is shallow, it can be made non-bottomed.

次に、斜面と略直交する方向に地盤改良を行って複数の斜面直交壁35eを施工する。斜面直交壁35eの深度は、軟弱層23の過剰間隙水圧の抑制のみを考慮して決定される。   Next, the ground is improved in a direction substantially orthogonal to the slope, and a plurality of slope orthogonal walls 35e are constructed. The depth of the slope orthogonal wall 35e is determined considering only suppression of excess pore water pressure of the soft layer 23.

その後、斜面地盤27の表層に、斜面直交壁35eの頂部に沿って、凸部57を形成する。凸部57は、斜面平行壁33eの硬化前に頂部近傍に埋設されたアンカ59によって、斜面平行壁33eに接続される。鉱さい集積場の斜面地盤27では、表層に沿って、図7(c)の矢印Jに示すように上流から降雨などの水が流れる場合がある。凸部57は、斜面地盤27の上流側の面から下流側の面を貫通する水抜き孔61を有する。水抜き孔61は、鉱さい集積場の上流から流れる水が鉱さい集積場の側方(図7(c)の右側と左側)に流れるように傾きをもたせて配置される。   Then, the convex part 57 is formed in the surface layer of the slope ground 27 along the top part of the slope orthogonal wall 35e. The convex portion 57 is connected to the slope parallel wall 33e by an anchor 59 embedded in the vicinity of the top before the slope parallel wall 33e is cured. On the slope ground 27 of the mine tailings, water such as rainfall may flow along the surface layer from the upstream as indicated by the arrow J in FIG. The convex part 57 has the drain hole 61 which penetrates the surface downstream from the upstream surface of the slope ground 27. The drain holes 61 are arranged with an inclination so that water flowing from the upstream side of the mine accumulation site flows to the side of the mine accumulation site (the right side and the left side in FIG. 7C).

第5の実施の形態では、斜面地盤27に斜面平行壁33eと斜面直交壁35eとを有する流動抑制構造31eを形成することによって、地震時に液状化しやすい軟弱層23の表層の過剰間隙水圧を抑制して斜面地盤27の表面の揺れを防止することができる。また、斜面平行壁33eの壁面摩擦により斜面地盤27の軟弱層23の滑りを抑制し、斜面直交壁35eで斜面平行壁33eの振動を抑制して、斜面地盤27の安定性を高めることができる。さらに、斜面地盤27の表層に斜面直交壁35eの頂部に沿って凸部57を形成することにより、水を鉱さい集積場の両側方に逃して斜面地盤27に浸透する水を削減することができるとともに、図7(b)の破線63に示すように斜面地盤27の表層の土砂が流動した場合に、流動土砂を凸部57で堰き止めることができる。   In the fifth embodiment, by forming the flow suppressing structure 31e having the inclined parallel wall 33e and the inclined orthogonal wall 35e on the inclined ground 27, the excess pore water pressure on the surface layer of the soft layer 23 that is liable to be liquefied during an earthquake is suppressed. As a result, the surface of the slope ground 27 can be prevented from shaking. Moreover, the slip of the soft layer 23 of the slope ground 27 is suppressed by the wall friction of the slope parallel wall 33e, and the vibration of the slope parallel wall 33e is suppressed by the slope orthogonal wall 35e, so that the stability of the slope ground 27 can be enhanced. . Furthermore, by forming the convex part 57 along the top of the slope orthogonal wall 35e on the surface layer of the slope ground 27, it is possible to reduce the water that escapes to both sides of the pit and accumulates in the slope ground 27. At the same time, as shown by the broken line 63 in FIG. 7B, when the surface sediment of the slope ground 27 flows, the fluid sediment can be dammed up by the convex portion 57.

第5の実施の形態では、斜面直交壁35eの深度を軟弱層23の過剰間隙水圧の抑制のみを考慮して決定することにより、広範囲にわたって地盤改良を行う場合にも、改良土量を削減できる。   In the fifth embodiment, by determining only the depth of the slope orthogonal wall 35e in consideration of suppression of excess pore water pressure of the soft layer 23, the amount of improved soil can be reduced even when ground improvement is performed over a wide range. .

図8は、他の流動抑制構造の概要を示す図である。図8(a)は、斜面地盤27の平面図である図8(b)に示す矢印G−Gによる斜面地盤2の斜面直交方向の縦断図である。図8(a)では、図の奥側が軟弱層23の流動方向の上流側、図の手前側が下流側である。図8(b)は、流動抑制構造31fを施工した斜面地盤27の平面図である。   FIG. 8 is a diagram showing an outline of another flow suppressing structure. FIG. 8A is a longitudinal sectional view in the direction perpendicular to the slope of the slope ground 2 taken along the arrow GG shown in FIG. 8B, which is a plan view of the slope ground 27. In FIG. 8A, the far side of the figure is the upstream side in the flow direction of the soft layer 23, and the near side of the figure is the downstream side. FIG.8 (b) is a top view of the slope ground 27 which constructed the flow suppression structure 31f.

第5の実施の形態では、凸部57を斜面直交壁35eの頂部に沿って形成したが、凸部57の配置はこれに限らない。図8(a)および図8(b)に示す流動抑制構造31fのように、斜面地盤27の表層に、凸部57fを、平面視が山型となるように配置してもよい。鉱さい集積場の斜面地盤27では、表層に沿って、図8(b)の矢印Hに示すように上流から降雨などの水が流れる場合がある。凸部57fを形成することにより、上流から流れる水が、凸部57fに沿って鉱さい集積場の側方(図8(b)の右側と左側)に流れる。図8(a)に示すように、凸部57fは、斜面平行壁33fとの交差部において、斜面平行壁33fの頂部付近にアンカ59fによって接続される。凸部57fは、斜面地盤27の上流側の面から下流側の面を貫通する水抜き孔61fを有する。水抜き孔61fは、鉱さい集積場の上流から流れる水が鉱さい集積場の側方に流れるように傾きをもたせて配置される。   In 5th Embodiment, although the convex part 57 was formed along the top part of the slope orthogonal wall 35e, arrangement | positioning of the convex part 57 is not restricted to this. As in the flow suppressing structure 31 f shown in FIGS. 8A and 8B, the convex portion 57 f may be arranged on the surface layer of the slope ground 27 so that the plan view has a mountain shape. In the slope ground 27 of the mine tailings, water such as rainfall may flow from the upstream as indicated by the arrow H in FIG. 8B along the surface layer. By forming the convex portion 57f, the water flowing from the upstream flows along the convex portion 57f to the sides of the slag accumulation field (the right side and the left side in FIG. 8B). As shown in FIG. 8A, the convex portion 57f is connected by an anchor 59f near the top of the inclined parallel wall 33f at the intersection with the inclined parallel wall 33f. The convex portion 57 f has a drain hole 61 f that penetrates the surface on the downstream side from the surface on the upstream side of the slope ground 27. The drain holes 61f are arranged with an inclination so that water flowing from the upstream side of the slag accumulation site flows to the side of the slag accumulation site.

図8(c)は、流動抑制構造31gを施工した斜面地盤27の平面図である。図8(c)に示す流動抑制構造31gのように、凸部57gを、平面視が谷型となるように配置してもよい。凸部57gを形成することにより、図8(c)の矢印Iに示すように上流から流れる水が、凸部57gに沿って鉱さい集積場の中央に流れる。凸部57gは、斜面平行壁33gとの交差部において、斜面平行壁33gの頂部付近に図示しないアンカによって接続される。凸部57gは、斜面地盤27の上流側の面から下流側の面を貫通する水抜き孔61gを有する。水抜き孔61gは、凸部57gの折れ曲がり部に水が溜まらないよう、鉱さい集積場の上流から流れてきた水を下流側に流すように配置される。   FIG.8 (c) is a top view of the slope ground 27 which constructed the flow suppression structure 31g. As in the flow suppressing structure 31g shown in FIG. 8C, the convex portion 57g may be arranged so that the plan view is a valley shape. By forming the convex portion 57g, water flowing from the upstream as shown by an arrow I in FIG. 8C flows along the convex portion 57g to the center of the slag accumulation field. The convex portion 57g is connected to the vicinity of the top of the inclined parallel wall 33g by an anchor (not shown) at the intersection with the inclined parallel wall 33g. The convex portion 57g has a drain hole 61g penetrating from the upstream surface of the slope ground 27 to the downstream surface. The drain hole 61g is arranged so that the water flowing from the upstream side of the slag accumulation field flows to the downstream side so that water does not collect in the bent part of the convex part 57g.

なお、上述した実施の形態では、斜面平行壁を施工した後に斜面直交壁を施工したが、施工順序はこれに限らない。図4(b)に示す例のように斜面平行壁と斜面直交壁とを一体に施工してもよい。斜面直交壁を施工した後に斜面平行壁を施工してもよい。格子壁の方向に関係なく、下流側から順に施工してもよい。   In the above-described embodiment, the slope orthogonal wall is constructed after the slope parallel wall is constructed, but the construction order is not limited to this. A slope parallel wall and a slope orthogonal wall may be constructed integrally as in the example shown in FIG. The slope parallel wall may be constructed after the slope orthogonal wall is constructed. Regardless of the direction of the lattice wall, the construction may be performed in order from the downstream side.

また、図1から図8に示す例では斜面平行壁を平面視で直線状に形成したが、斜面平行壁の形状はこれに限らない。図9は、斜面平行壁を平面視でジグザグ状に形成した例を示す図である。   In the example shown in FIGS. 1 to 8, the inclined parallel wall is formed linearly in plan view, but the shape of the inclined parallel wall is not limited to this. FIG. 9 is a diagram showing an example in which the inclined parallel walls are formed in a zigzag shape in plan view.

図9(a)は、流動抑制構造1aを施工した斜面地盤2の平面図である。図9(a)に示すように、豪雨等による斜面地盤2の滑りを抑制するために、平面視でジグザグ状の斜面平行壁5aを所定の間隔で施工して流動抑制構造1aとしてもよい。斜面平行壁5aは、平面視で斜面に平行な軸65を中心として軸65の左右に所定の振れ幅でジグザグ状に形成される。   Fig.9 (a) is a top view of the slope ground 2 which constructed the flow suppression structure 1a. As shown in FIG. 9 (a), in order to suppress slippage of the slope ground 2 due to heavy rain or the like, a zigzag slope parallel wall 5a in a plan view may be constructed at a predetermined interval to form the flow suppression structure 1a. The inclined parallel wall 5a is formed in a zigzag shape with a predetermined swing width on the left and right sides of the shaft 65 around the shaft 65 parallel to the inclined surface in plan view.

図9(b)は、流動抑制構造31hを施工した斜面地盤27の平面図である。図9(b)に示すように、地震等による斜面地盤27の液状化を抑制するために、平面視でジグザグ状の斜面平行壁33hを所定の間隔で施工し、斜面直交壁35hと合わせて流動抑制構造31hとしてもよい。斜面平行壁33hは、平面視で斜面に平行な軸67を中心として軸67の左右に所定の振れ幅でジグザグ状に形成される。このように、本発明では、斜面平行壁は、全体として斜面に略平行に形成されれば、部分的に多少の傾きを持って形成されてもよい。   FIG.9 (b) is a top view of the slope ground 27 which constructed the flow suppression structure 31h. As shown in FIG. 9 (b), in order to suppress the liquefaction of the slope ground 27 due to an earthquake or the like, zigzag parallel slope walls 33h are constructed at a predetermined interval in plan view, and are combined with the slope orthogonal walls 35h. It is good also as a flow suppression structure 31h. The inclined parallel wall 33h is formed in a zigzag shape with a predetermined swing width on the left and right sides of the shaft 67 about the shaft 67 parallel to the inclined surface in plan view. As described above, in the present invention, the inclined parallel wall may be formed with a slight inclination as long as it is formed substantially parallel to the inclined surface as a whole.

以上、添付図を参照しながら、本発明の実施形態を説明したが、本発明の技術的範囲は、前述した実施形態に左右されない。当業者であれば、特許請求の範囲に記載された技術的思想の範疇内において各種の変更例または修正例に想到し得ることは明らかであり、それらについても当然に本発明の技術的範囲に属するものと了解される。   As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

1、1a、31、31a、31b、31c、31d、31e、31f、31g、31h………流動抑制構造
2、27………斜面地盤
3………滑り層
4………基礎地盤
5、5a、33、33a、33b、33c、33d、33e、33f、33g、33h………斜面平行壁
7、37、39、37c………間隔
9………壁厚
11………滑り円弧
15………斜面
17−1、17−2、…、17−n………分割土塊
19………鉱さい集積場
21………非液状化層
23………軟弱層
25………基礎堤
41………補強部分
43、45………深度
47………土被り部
51………杭
57、57f、57g………凸部
61………水抜き孔
1, 1a, 31, 31a, 31b, 31c, 31d, 31e, 31f, 31g, 31h ......... Flow suppression structure 2, 27 ......... Slope ground 3 ......... Sliding layer 4 ......... Base ground 5, 5a 33, 33a, 33b, 33c, 33d, 33e, 33f, 33g, 33h ......... Slope parallel walls 7, 37, 39, 37c ......... Interval 9 ......... Wall thickness 11 ......... Slide arc 15 ... ... Slopes 17-1, 17-2, ..., 17-n ......... Division block 19 ......... Mine dump 21 ......... Non-liquefaction layer 23 ......... Soft layer 25 ......... Basement 41 ... ... Reinforcement part 43, 45 ......... Depth 47 ... ... Soil cover part 51 ... ... Pile 57, 57f, 57g ... ... Convex part 61 ... ... Drainage hole

Claims (10)

斜面地盤の流動を抑制する方法であって、
斜面地盤に、斜面と平行方向に所定の間隔で地盤改良を行い、地盤改良部である斜面平行壁を施工する工程aを具備し、
前記所定の間隔および前記斜面平行壁の壁厚は、地盤改良を行っていない未改良部の粘着力と前記地盤改良部の粘着力とから求められる複合地盤の粘着力を用いて算出した前記複合地盤の滑り安全率が1を超えるように設定され、
前記斜面平行壁は過剰間隙水圧の抑制と斜面の滑り抑制に必要な深度まで改良され、
前記斜面平行壁の壁面摩擦により前記斜面地盤の滑りを抑制することを特徴とする斜面地盤の流動抑制方法。
A method for suppressing the flow of slope ground,
On the slope ground, the ground improvement is performed at a predetermined interval in a direction parallel to the slope, and a process a for constructing a slope parallel wall which is a ground improvement portion is provided.
The composite distance calculated by using the adhesive force of the composite ground obtained from the adhesive force of the unimproved portion not subjected to ground improvement and the adhesive force of the ground improved portion is determined as the predetermined interval and the wall thickness of the slope parallel wall. The ground slip safety factor is set to exceed 1,
The slope parallel wall is improved to a depth necessary for suppressing excess pore water pressure and slippage of the slope,
A slope ground flow suppression method, wherein slippage of the slope ground is suppressed by wall friction of the slope parallel wall.
前記斜面平行壁は、平面視でジグザグ形状に形成されることを特徴とする請求項1記載の斜面地盤の流動抑制方法。   2. The slope ground flow suppression method according to claim 1, wherein the slope parallel wall is formed in a zigzag shape in plan view. 前記斜面地盤に、前記斜面と略直交する方向に所定の間隔で地盤改良を行い、地盤改良部である斜面直交壁を施工する工程bをさらに具備し、
前記斜面直交壁は、過剰間隙水圧抑制に必要な深度だけ改良され、
前記斜面直交壁により前記斜面地盤の液状化を抑制することを特徴とする請求項1または請求項2記載の斜面地盤の流動抑制方法。
In the slope ground, the ground improvement is performed at a predetermined interval in a direction substantially orthogonal to the slope, further comprising a step b of constructing a slope orthogonal wall that is a ground improvement portion,
The inclined wall perpendicular to the slope is improved by a depth necessary for suppressing excess pore water pressure,
The liquefaction of the slope ground according to claim 1 or 2, wherein the slope orthogonal wall suppresses liquefaction of the slope ground.
前記斜面平行壁と前記斜面直交壁との交差部に、杭が設置されることを特徴とする請求項3記載の斜面地盤の流動抑制方法。   The method for suppressing the slope ground flow according to claim 3, wherein a pile is installed at an intersecting portion between the slope parallel wall and the slope orthogonal wall. 少なくとも一部の前記斜面直交壁の深度が、前記斜面平行壁の深度よりも浅いことを特徴とする請求項3または請求項4のいずれかに記載の斜面地盤の流動抑制方法。   5. The slope ground flow suppression method according to claim 3, wherein a depth of at least a part of the orthogonal wall of the slope is shallower than a depth of the parallel wall of the slope. 地盤改良で発生する吹上土を用いて、前記斜面地盤の表層を被覆する土被り部を設置する工程cをさらに具備することを特徴とする請求項1から請求項5のいずれかに記載の斜面地盤の流動抑制方法。   The slope according to any one of claims 1 to 5, further comprising a step (c) of installing a soil covering portion that covers a surface layer of the slope ground using a blown up soil generated by ground improvement. Ground flow control method. 前記斜面地盤の表層に凸部が形成され、前記凸部が前記斜面平行壁の頂部近傍に接続されることを特徴とする請求項1から請求項6のいずれかに記載の斜面地盤の流動抑制方法。   7. The flow suppression of the slope ground according to claim 1, wherein a convex portion is formed on a surface layer of the slope ground, and the convex portion is connected to a vicinity of a top portion of the slope parallel wall. Method. 斜面地盤の流動を抑制する構造であって、
斜面地盤に斜面と平行方向に所定の間隔で形成された地盤改良部である斜面平行壁を具備し、
前記所定の間隔および前記斜面平行壁の壁厚は、地盤改良を行っていない未改良部の粘着力と前記地盤改良部の粘着力とから求められる複合地盤の粘着力を用いて算出した前記複合地盤の滑り安全率が1を超えるように設定され、
前記斜面平行壁が、過剰間隙水圧抑制と斜面の滑り抑制に必要な深度まで形成され、
前記斜面平行壁の壁面摩擦により前記斜面地盤の滑りが抑制されることを特徴とする斜面地盤の流動抑制構造。
A structure that suppresses the flow of slope ground,
The slope ground has slope parallel walls that are ground improvement parts formed at predetermined intervals in a direction parallel to the slope,
The composite distance calculated by using the adhesive force of the composite ground obtained from the adhesive force of the unimproved portion not subjected to ground improvement and the adhesive force of the ground improved portion is determined as the predetermined interval and the wall thickness of the slope parallel wall. The ground slip safety factor is set to exceed 1,
The slope parallel wall is formed to a depth necessary for suppressing excess pore water pressure and slope slippage,
A slope ground flow restraining structure, wherein slippage of the slope ground is restrained by wall friction of the slope parallel walls.
前記斜面平行壁が、平面視でジグザグ形状に形成されることを特徴とする請求項8記載の斜面地盤の流動抑制構造。   9. The structure for suppressing flow of a slope ground according to claim 8, wherein the slope parallel wall is formed in a zigzag shape in a plan view. 前記斜面地盤に前記斜面と略直交する方向に所定の間隔で形成された地盤改良部である斜面直交壁をさらに具備し、
前記斜面直交壁は、過剰間隙水圧抑制に必要な深度だけ形成され、少なくとも一部の前記斜面直交壁の深度が、前記斜面平行壁の深度よりも浅く形成され、
前記斜面直交壁により前記斜面地盤の液状化が抑制されることを特徴とする請求項8または請求項9記載の斜面地盤の流動抑制構造。
Further comprising a slope orthogonal wall that is a ground improvement portion formed at a predetermined interval in a direction substantially orthogonal to the slope on the slope ground,
The slope orthogonal wall is formed to a depth necessary for excessive pore water pressure suppression, and at least a part of the slope orthogonal wall is formed to be shallower than the depth of the slope parallel wall,
The liquefaction of the slope ground is suppressed by the slope orthogonal wall, The slope ground flow restraining structure according to claim 8 or 9.
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