JP2017119968A - Evaluation method of pile composed of soil cement column row wall - Google Patents
Evaluation method of pile composed of soil cement column row wall Download PDFInfo
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Abstract
Description
本発明は、仮設山留め壁として機能するソイルセメント柱列壁を、仮設山留め壁の前面側に構築した構造物の本設杭として利用するための、ソイルセメント柱列壁よりなる杭の評価方法に関する。 The present invention relates to a method for evaluating a pile including a soil cement column wall, in which a soil cement column wall that functions as a temporary mountain retaining wall is used as a permanent pile of a structure constructed on the front side of the temporary mountain retaining wall.
従来より、仮設山留め壁として機能するソイルセメント柱列壁を構造物の本設杭として利用する場合には、ソイルセメント柱列壁を構成する複数のソイルセメント柱各々を単杭とみなして、単杭の許容鉛直支持力を地盤から定まる許容鉛直支持力にて評価する方法が一般に知られている。ただし、この場合にはあらかじめ、地盤から定まる許容鉛直支持力が、杭材料の許容応力度より定まる許容鉛直支持力を超えないよう対処する必要が生じる。 Conventionally, when a soil cement column wall that functions as a temporary retaining wall is used as a main pile of a structure, each of the plurality of soil cement columns constituting the soil cement column wall is regarded as a single pile, A method is generally known in which an allowable vertical bearing force is evaluated by an allowable vertical bearing force determined from the ground. However, in this case, it is necessary to cope in advance so that the allowable vertical bearing force determined from the ground does not exceed the allowable vertical bearing force determined from the allowable stress level of the pile material.
このため、例えば、特許文献１では、セメント系固化材とＨ形鋼よりなり、建物の地下部を構築する際の土留壁としての機能を有する地中壁体を、建物の地中の外壁として使用するとともに支持杭として使用するべく、地中壁体を従来の土留壁と比較して強度的にはるかに優れた構造物に構築している。また、地中壁体の下端部を支持層内に埋設するとともに、Ｈ形鋼下端部にはセメント系固化材より強度の高いセメント系根固め材を打設している。 For this reason, for example, in patent document 1, the underground wall body which consists of a cement-type solidification material and H-section steel, and has a function as a retaining wall at the time of constructing the underground part of a building is used as an outer wall in the underground of a building. In order to use it as a support pile, the underground wall is constructed in a structure that is far superior in strength compared to conventional retaining walls. In addition, the lower end portion of the underground wall is embedded in the support layer, and a cement-based solidifying material having a higher strength than the cement-based solidifying material is placed at the lower end portion of the H-shaped steel.
しかし、上記の地中壁体のように本設杭としての機能を確保するべく、従来の土留壁と比較して強度を向上させ、また、セメント系根固め材を打設することは、施工を煩雑にするだけでなく材料費が嵩むこととなり、合理的な方法とはいえない。 However, in order to secure the function as a built-up pile like the above-mentioned underground wall body, the strength is improved compared to the conventional retaining wall, and the placement of cement-based rooting material is This is not only a complicated method, but also increases the material cost.
また、地中壁体の下端部にセメント系根固め材を打設する方法に替えて、Ｈ形鋼の先端に閉塞加工を施すことで鉛直支持力を確保することも考えられるが、このような場合には、セメント系固化材中にＨ形鋼を建て込む際の施工性が大幅に低下するといった課題が生じる。 In addition, instead of the method of placing a cement-based rooting material at the lower end of the underground wall body, it is conceivable to secure a vertical supporting force by applying a closing process to the tip of the H-shaped steel. In such a case, there arises a problem that the workability when the H-section steel is built in the cement-based solidified material is significantly lowered.
本発明は、かかる課題に鑑みなされたものであって、その主な目的は、仮設土留め壁としての機能のみを考慮し構築したソイルセメント柱列壁であっても、本設杭として利用するべく許容鉛直支持力を評価することの可能な、ソイルセメント柱列壁よりなる杭の評価方法を提供することである。 The present invention has been made in view of such problems, and the main purpose of the present invention is to use a soil cement column wall constructed only in consideration of the function as a temporary earth retaining wall as a permanent pile. Therefore, it is intended to provide a method for evaluating a pile made of soil cement column wall that can evaluate an allowable vertical bearing capacity.
かかる目的を達成するため、本発明のソイルセメント柱列壁よりなる杭の評価方法は、仮設山留め壁として機能するソイルセメント柱列壁を、前記仮設山留め壁を利用して地下部分を構築した構造物の本設杭として利用するための、ソイルセメント柱列壁よりなる杭の評価方法であって、前記ソイルセメント柱列壁において、芯材が埋設された複数のソイルセメント柱各々を単杭とみなして、前記構造物の底盤下面高さを杭頭、前記芯材の先端部を杭先端部に設定し、地盤から定まる極限支持力と杭材料の許容応力度から定まる極限支持力の両者を算定したうえで、いずれか小さい方の値を前記単杭の極限支持力として選定し、該単杭の許容鉛直支持力を算定することを特徴とする。 In order to achieve this object, the pile evaluation method of the soil cement column wall according to the present invention is a structure in which a soil cement column wall functioning as a temporary mountain retaining wall is constructed by using the temporary mountain retaining wall to construct an underground portion. A method for evaluating a pile composed of soil cement column walls for use as a main pile of objects, wherein each of the plurality of soil cement columns in which a core material is embedded is regarded as a single pile in the soil cement column wall The bottom bottom height of the structure was set to the pile head and the tip of the core was set to the tip of the pile, and both the ultimate bearing force determined from the ground and the ultimate bearing force determined from the allowable stress of the pile material were calculated. On the other hand, the smaller value is selected as the ultimate bearing capacity of the single pile, and the allowable vertical bearing capacity of the single pile is calculated.
本発明によれば、ソイルセメント柱列壁において、芯材が埋設された複数のソイルセメント柱各々を単杭とみなし、その極限支持力を地盤から定まる極限支持力と杭材料の許容応力度から定まる極限支持力の両者から選定する。これにより、本設杭として利用しようとするソイルセメント柱列壁は、杭材料の許容応力度より定まる許容鉛直支持力を地盤から定まる許容鉛直支持力が超えることのないよう、予め仕様を設定して構築したものではなくとも、構造物の荷重の一部を負担する本設杭として利用することが可能となる。 According to the present invention, in the soil cement column wall, each of the plurality of soil cement columns in which the core material is embedded is regarded as a single pile, and the ultimate support force is determined from the ultimate support force determined from the ground and the allowable stress of the pile material. Select from both the ultimate support capacity. In this way, the specifications of the soil cement column wall to be used as a permanent pile are set in advance so that the allowable vertical bearing force determined from the allowable stress level of the pile material does not exceed the allowable vertical bearing force determined from the ground. Even if it is not constructed, it can be used as a permanent pile that bears part of the load of the structure.
したがって、ソイルセメント柱列壁は、少なくとも仮設山留め壁として機能する仕様を確保していればいずれの構造を有するものであってもよく、実情に見合った設計に基づいて経済的に構築することが可能となる。 Therefore, the soil cement column wall may have any structure as long as it has specifications that function as at least a temporary retaining wall, and can be constructed economically based on a design that matches the actual situation. It becomes possible.
本発明は、仮設山留め壁として構築したソイルセメント柱列壁が副次的に有する壁杭としての支持性能を、仮設山留め壁を利用して地下部分を構築した構造物の荷重の一部を支持する本設杭として利用するための、ソイルセメント柱列壁よりなる杭の評価方法に関するものである。 The present invention supports the support performance as a wall pile that the soil cement column wall constructed as a temporary retaining wall as a secondary, and supports a part of the load of the structure in which the underground part is constructed using the temporary retaining wall. The present invention relates to a method for evaluating a pile made of soil cement column walls for use as a permanent pile.
以下に、本発明のソイルセメント柱列壁よりなる杭の設計方法を、図１〜図６を参照して説明する。なお、本実施の形態では、構造物４が地下部４１のみを有する場合を事例とするが、必ずしもこれに限定されるものではなく、地下部４１と地上部を有するものであってもよい。 Below, the design method of the pile which consists of the soil cement column wall of this invention is demonstrated with reference to FIGS. In addition, in this Embodiment, although the case where the structure 4 has only the underground part 41 is taken as an example, it is not necessarily limited to this, You may have an underground part 41 and an above-ground part.
図１で示すように、地下部４１を有する構造物４の外周には、地下部４１を構築する際に仮設山留め壁として使用したソイルセメント柱列壁１が配置されている。ソイルセメント柱列壁１は、図５で示すように、芯材２が挿入された複数のソイルセメント柱３を連続一体に構築したものであり、ソイルセメント柱３は、例えば、多軸オーガーにて原地盤を削孔し、その先端よりセメントスラリーを吐出して削孔撹拌を行うことにより構築され、芯材２はＨ形鋼よりなる。 As shown in FIG. 1, a soil cement column wall 1 used as a temporary retaining wall when the underground part 41 is constructed is disposed on the outer periphery of the structure 4 having the underground part 41. As shown in FIG. 5, the soil cement column wall 1 is constructed by continuously integrating a plurality of soil cement columns 3 into which the core material 2 is inserted. The core ground 2 is made of an H-shaped steel. The core material 2 is made of H-section steel.
本実施の形態では、ソイルセメント柱３の一軸圧縮強度として高さ方向に一様な０．５Ｎ／ｍｍ2程度を確保するとともに、スタッドは設置しない構成のものを採用しているが、仮設山留め壁として機能するものであって、かつ芯材２とソイルセメント柱３が支持層５に根入れされているものであれば、ソイルセメントの一軸圧縮強度や芯材に対するスタッドの設置の有無等、その構造はなんら制限されるものではない。 In this embodiment, the uniaxial compressive strength of the soil cement column 3 is ensured to be about 0.5 N / mm 2 which is uniform in the height direction, and the stud is not installed. If it functions as a wall and the core material 2 and the soil cement pillar 3 are embedded in the support layer 5, the uniaxial compressive strength of the soil cement and the presence or absence of studs on the core material, etc. The structure is not limited at all.
上述する構成のソイルセメント柱列壁１は、図１で示すように、構造物４の鉛直荷重が、芯材２から芯材２とソイルセメント柱３の接触面における付着力や支圧によりソイルセメント柱３に伝達され、ソイルセメント柱３から周面摩擦力および先端支持力により周辺地盤へ伝達される。したがって、ソイルセメント柱列壁１を本設の壁杭とみなして、構造物４の鉛直荷重の一部を負担させる設計とすれば、構造物４の基礎構造は、負担すべき構造物４の鉛直荷重が低減されるため、杭の本数を削減する、もしくは杭径を小さくする等、経済的な設計を行うことができる。 As shown in FIG. 1, the soil cement column wall 1 having the above-described structure is configured such that the vertical load of the structure 4 is caused by the adhesive force and the bearing pressure on the contact surface between the core material 2 and the core material 2 and the soil cement column 3. It is transmitted to the cement column 3 and transmitted from the soil cement column 3 to the surrounding ground by the peripheral frictional force and the tip support force. Therefore, if the soil cement column wall 1 is regarded as a main wall pile and a part of the vertical load of the structure 4 is to be borne, the foundation structure of the structure 4 is the structure 4 to be borne. Since the vertical load is reduced, an economical design such as reducing the number of piles or reducing the pile diameter can be performed.
そこで本実施の形態では、仮設山留め壁として構築したソイルセメント柱列壁１が副次的に有する壁杭としての支持性能を評価するにあたり、ソイルセメント柱列壁１において、図５で示すように、芯材２が埋設された複数のソイルセメント柱３各々を単杭６とみなし、これら単杭６の許容鉛直支持力を評価することとした。 Therefore, in this embodiment, in evaluating the support performance as a wall pile that the soil cement column wall 1 constructed as a temporary mountain retaining wall has as a secondary, in the soil cement column wall 1, as shown in FIG. Each of the plurality of soil cement columns 3 in which the core material 2 is embedded is regarded as a single pile 6 and the allowable vertical bearing force of these single piles 6 is evaluated.
以下に、図２のフロー図に従いながら、ソイルセメント柱列壁１よりなる杭の評価方法の手順を示す。なお、ソイルセメント柱列壁１が壁杭として機能する高さ範囲は、図１で示すように、構造物４の底盤４２の下面から芯材２の先端部２１までであるから、単杭６の杭頭部を構造物４の底盤４２の下面に相当する高さに、杭先端部を芯材２の先端部２１に相当する高さにそれぞれ設定している。 Below, the procedure of the evaluation method of the pile which consists of the soil cement column wall 1 is shown, following the flowchart of FIG. In addition, since the height range in which the soil cement column wall 1 functions as a wall pile is from the lower surface of the bottom plate 42 of the structure 4 to the tip portion 21 of the core member 2 as shown in FIG. The pile head is set to a height corresponding to the lower surface of the bottom plate 42 of the structure 4, and the pile tip portion is set to a height corresponding to the tip portion 21 of the core member 2.
〈杭材料の許容応力度から定まる極限支持力の算定：ＳＴＥＰ１〉
本実施の形態において、単杭６の杭材料は芯材３とソイルセメント柱２であり、杭材料の許容応力度から定まる極限支持力Ｒuc1は、極限付着力Ｒfucと極限先端支持力Ｒpucの和で表すことができる。そこでまず、極限付着力Ｒfuc の算定方法を以下に示す。
<Calculation of ultimate bearing capacity determined from allowable stress of pile material: STEP1>
In the present embodiment, the pile material of the single pile 6 is the core material 3 and the soil cement column 2, and the ultimate supporting force R uc1 determined from the allowable stress level of the pile material is the ultimate adhesion force R fuc and the ultimate tip supporting force R. It can be expressed as the sum of puc . Therefore, first, the calculation method of the ultimate adhesion R fuc is shown below.
〈極限付着力Ｒfucの算定：ＳＴＥＰ１−１〉
極限付着力Ｒfucは（１）式で示すように、残留付着力度τbu*から算定した芯材２とソイルセメント柱３との間の極限付着力Ｒ’fucと、残留付着力度τbu*とせん断強度τs*から算定した芯材２とソイルセメント柱３との間の極限付着力Ｒ”fucのうち、いずれか小さい値を採用する。
<Calculation of ultimate adhesion R fuc : STEP1-1>
As shown in equation (1), the ultimate adhesive force R fuc is calculated from the residual adhesive strength τ bu *, and the ultimate adhesive force R ′ fuc between the core material 2 and the soil cement column 3 and the residual adhesive strength τ bu *. The smaller value of the ultimate adhesive force R ″ fuc between the core material 2 and the soil cement column 3 calculated from the shear strength τ s * is adopted.
芯材２とソイルセメント柱３との間の極限付着力Ｒ’fucとＲ”fucを算定するにあたっては、図６で示すように高さ範囲として、杭先端部より上方０．５ｍから杭頭部までの間の区間Ｌを設定するが、芯材２におけるスタッドの有無でその計算方法が異なる。芯材２の先端部近傍にスタッドがない場合、極限付着力Ｒ’fuc、は（２）式にて、極限付着力Ｒ”fucは（３）式にて算定される。
〈スタッドがない場合〉
In calculating the ultimate adhesion R ' fuc and R " fuc between the core material 2 and the soil cement column 3, as shown in Fig. 6, the height of the pile head from 0.5m above the pile tip as shown in Fig. 6 The calculation method differs depending on the presence or absence of a stud in the core material 2. When there is no stud near the tip of the core material 2, the ultimate adhesion R ′ fuc is (2). In the equation, the ultimate adhesion R ″ fuc is calculated by the equation (3).
<When there is no stud>
一方、芯材２の先端部近傍にスタッドがある場合には、極限付着力Ｒ’fucは（４）式にて、極限付着力Ｒ”fucは（５）式にて算定される。なお、図３に示すように、本実施の形態では芯材２がＨ形鋼であるから、Ｂはフランジ幅、Ｈはウェブ幅（Ｈ形鋼のせい）をさす。
〈スタッドがある場合〉
このとき、
On the other hand, when there is a stud in the vicinity of the tip of the core material 2, the ultimate adhesion R ′ fuc is calculated by the equation (4), and the ultimate adhesion R ″ fuc is calculated by the equation (5). As shown in FIG. 3, in the present embodiment, the core material 2 is an H-shaped steel, so B indicates the flange width and H indicates the web width (because of the H-shaped steel).
<When there is a stud>
At this time,
なお、残留付着力度τbu*は、極限付着力Ｒfucが地震等によりソイルセメント柱３が損傷を受けた後にも耐力を担保できる評価式となるよう定義したものであり、せん断強度τs*、およびスタッドの支圧強度τst*と同様に、ソイルセメント設計強度ｑucに係数をかけて規定されるものである。また、それぞれの係数は、地盤条件や構造物４の条件等を鑑み、あらかじめ模型実験を行い適宜設定する。 The residual adhesive strength τ bu * is defined so that the ultimate adhesive strength R fuc is an evaluation formula that can guarantee the proof strength even after the soil cement column 3 is damaged by an earthquake or the like. The shear strength τ s * As well as the bearing strength τ st * of the stud, the soil cement design strength q uc is defined by a factor. In addition, each coefficient is appropriately set by conducting a model experiment in advance in consideration of the ground conditions, the conditions of the structure 4, and the like.
〈極限先端支持力Ｒpucの算定：ＳＴＥＰ１−２〉
極限先端支持力Ｒpucは、本実施の形態において芯材２の実断面積Ａp*に、定数νpおよびνpstと低減係数ｒuをかけあわせることで算定しており、芯材２の先端部近傍にスタッドがない場合には（６）式にて、またスタッドがある場合には、芯材２の実断面積Ａp*にスタッドの支圧面積を含めた上で、（７）式にて算定される。
〈スタッドがない場合〉
〈スタッドがある場合〉
このとき、
<Calculation of ultimate tip bearing force R puc : STEP1-2>
Ultimate tip support force R puc is the actual cross-sectional area A p * of the core member 2 in this embodiment, are calculated by Kakeawaseru constant [nu p and [nu pst the reduction factor r u, the core member 2 If there is no stud near the tip, use formula (6). If there is a stud, add the bearing area of the stud to the actual cross-sectional area A p * of the core 2 (7) Calculated by the formula.
<When there is no stud>
<When there is a stud>
At this time,
ここで、極限先端支持力Ｒpucを算定するにあたり、ソイルセメント設計強度ｑucに応じた定数νpおよびνpstを採用している。定数νpおよびνpstは、実大載荷試験の結果に基づくものであり、芯材２先端への到達軸力とソイルセメント柱３の強度から、それらの荷重伝達機構を考慮して、これら定数を下限値として設定している。 Here, in calculating the ultimate tip bearing force R puc , constants ν p and ν pst corresponding to the soil cement design strength q uc are employed. The constants ν p and ν pst are based on the results of a full-scale loading test, and these constants are taken into consideration from the ultimate axial force at the tip of the core material 2 and the strength of the soil cement column 3 in consideration of the load transmission mechanism. Is set as the lower limit.
なお、図４で示すように、ソイルセメント設計強度ｑucと定数νpおよびνpstはそれぞれ比例関係にあることから、定数νpおよびνpstはソイルセメント設計強度ｑucに応じて図４から適宜直線補完し設定すればよい。 As shown in FIG. 4, since the soil cement design strength q uc and the constants ν p and ν pst are proportional to each other, the constants ν p and ν pst are obtained from FIG. 4 according to the soil cement design strength q uc . What is necessary is just to complement and set a line suitably.
〈杭材料の許容応力度から定まる極限支持力Ｒuc1：ＳＴＥＰ１−３〉
上記の算定結果である極限付着力Ｒfucと極限先端支持力Ｒpucとを足し合わせることにより、杭材料の許容応力度から定まる極限支持力Ｒuc1が（８）式のように算定できる。
<Ultimate bearing force R uc1 : STEP 1-3 determined from the allowable stress level of the pile material>
By adding the ultimate adhesion force R fuc and the ultimate tip support force R puc which are the above calculation results, the ultimate support force R uc1 determined from the allowable stress level of the pile material can be calculated as shown in Equation (8).
上記のとおり、杭材料の許容応力度から定まる極限支持力Ｒuc1の算定では、芯材２の先端部近傍にスタッドが設けられているか否かにより算定方法が異なる点が、大きな特徴である。スタッドの有無が、極限付着力Ｒfucおよび極限先端支持力Ｒpucの両者に反映されているため、芯材２にスタッドがない場合であっても極限支持力Ｒuc1に対して実情に合った安全側の評価を行うことが可能となる。 As described above, in the calculation of the ultimate bearing force Ruc1 determined from the allowable stress level of the pile material, a great feature is that the calculation method differs depending on whether or not a stud is provided in the vicinity of the tip of the core material 2. The presence / absence of the stud is reflected in both the ultimate adhesive force R fuc and the ultimate tip support force R puc , so that even if the core material 2 has no stud, it matches the actual situation with respect to the ultimate support force R uc1 . It is possible to perform a safety evaluation.
〈地盤から定まる極限支持力の算定：ＳＴＥＰ２〉
地盤から定まる極限支持力Ｒuc2は、地盤から定まる極限先端支持力Ｒpusと地盤から定まる極限周面摩擦力Ｒfusの和で表すことができる。
<Calculation of ultimate bearing capacity determined from the ground: STEP2>
The ultimate support force R uc2 determined from the ground can be represented by the sum of the ultimate tip support force R pus determined from the ground and the limit peripheral surface friction force R fus determined from the ground.
〈極限周面摩擦力Ｒfusの算定：ＳＴＥＰ２−２〉
本実施の形態では、図６で示すように、極限周面摩擦力Ｒfusを算定する高さ範囲として、杭先端部より上方０．５ｍから杭頭部までの間の区間Ｌを設定し、地盤から定まる極限周面摩擦力Ｒfusを（１０）式より算定している。
このとき、
<Calculation of ultimate peripheral friction force R fus : STEP2-2 >
In this embodiment, as shown in FIG. 6, as a height range for calculating the ultimate peripheral friction force R fus , a section L between 0.5 m above the pile tip and the pile head is set, The ultimate peripheral friction force R fus determined from the ground is calculated from the equation (10).
At this time,
ここで、周長φは図５で示すように、平面視におけるソイルセメント柱２と地盤とが接する部分の長さである。また、極限周面摩擦力Ｒfusはソイルセメント柱２の周長を用いているが、極限先端支持力Ｒpusは、ソイルセメント柱２に破壊が生じる場合を想定し安全側に評価するべく、ソイルセメント柱２の断面積を用いず、芯材２の閉塞面積Ａpを採用している。 Here, as shown in FIG. 5, the circumferential length φ is the length of the portion where the soil cement column 2 and the ground are in contact in plan view. In addition, although the peripheral circumferential surface friction force R fus uses the circumference of the soil cement column 2, the ultimate tip supporting force R pus is assumed to be evaluated safely on the assumption that the soil cement column 2 is broken. without using the cross-sectional area of the soil cement pillar 2, it employs a closed area a p of the core 2.
〈地盤から定まる極限支持力Ｒuc2：ＳＴＥＰ２−３〉
上記の算定結果である極限先端支持力Ｒpusと極限周面摩擦力Ｒfusとを足し合わせることで、地盤から定まる極限支持力Ｒuc2は（１１）式のように算定できる。
<Extreme support force Ruc2 determined from the ground: STEP2-3>
The ultimate support force R uc2 determined from the ground can be calculated by adding the limit tip support force R pus and the limit peripheral surface friction force R fus , which are the above calculation results, as shown in Equation (11).
〈単杭６の極限支持力：ＳＴＥＰ３〉
ＳＴＥＰ１で算定した芯材２及びソイルセメント柱３の許容応力度から定まる極限支持力Ｒuc1と、ＳＴＥＰ２で算定した地盤から定まる極限支持力Ｒuc2とを比較し、単杭６の極限支持力Ｒucをとして、（１２）式で示すようにいずれか値の小さい方を選定する。
<Ultimate bearing capacity of single pile 6: STEP3>
The ultimate bearing capacity R uc1 determined from the allowable stress of the core material 2 and soil cement column 3 calculated in STEP 1 is compared with the ultimate bearing capacity R uc2 determined from the ground calculated in STEP 2, and the ultimate bearing capacity R of the single pile 6 is compared. Using uc , the smaller value is selected as shown in equation (12).
（１２）式より得られた単杭６の極限支持力Ｒucを、（１３）式で示すように、安全率で除することにより、単杭６の許容鉛直支持力Ｒacが算定される。
このとき、
Rac：載荷試験を行なわない場合の許容鉛直支持力 (kN)
Fs：安全率（長期3、短期1.5）
By dividing the ultimate bearing capacity R uc of the single pile 6 obtained from the expression (12) by the safety factor as shown in the expression (13), the allowable vertical bearing capacity R ac of the single pile 6 is calculated. .
At this time,
R ac : Permissible vertical bearing force without load test (kN)
F s : Safety factor (long-term 3, short-term 1.5)
上記の算定結果から、ソイルセメント柱列壁１を本設杭として利用する場合には、単杭６が上記の鉛直支持力Ｒacを有するものとして、ソイルセメント柱列壁１が壁杭として負担可能な構造物４の鉛直荷重を算定し、その分を差し引いて構造物４における基礎構造の設計を行えばよい。 From the above calculation results, when the soil cement column wall 1 is used as a permanent pile, it is assumed that the single pile 6 has the vertical bearing force R ac and the soil cement column wall 1 is burdened as a wall pile. What is necessary is just to calculate the vertical load of the possible structure 4, and deduct the part and design the foundation structure in the structure 4.
上記の方法によれば、ソイルセメント柱列壁１を構成する、芯材２が埋設された複数のソイルセメント柱３各々を単杭６とみなし、単杭６の極限支持力に、杭材料の許容応力度から定まる極限支持力Ｒuc1と地盤から定まる極限支持力Ｒuc2のうち、値の小さい方を選定する。これにより、ソイルセメント柱列壁１は、従来のように、杭材料の許容応力度より定まる許容鉛直支持力を地盤から定まる許容鉛直支持力が超えないよう、予め仕様を設定して構築したものではなくても、地下部４１を有する構造物４について、荷重の一部を負担する本設杭として使用することが可能となる。 According to the above method, each of the plurality of soil cement columns 3 in which the core material 2 is embedded, which constitutes the soil cement column wall 1, is regarded as a single pile 6, and the ultimate supporting force of the single pile 6 is of ultimate bearing capacity R uc2 determined from ultimate bearing capacity R uc1 and ground determined from allowable stress, to select a smaller value. As a result, the soil cement column wall 1 is constructed by setting specifications in advance so that the allowable vertical support force determined from the allowable stress level of the pile material does not exceed the allowable vertical support force determined from the ground as in the past. Even if it is not, about the structure 4 which has the underground part 41, it becomes possible to use as a permanent pile which bears a part of load.
したがって、ソイルセメント柱列壁１を本設杭として利用するべく、地盤の強度に対応させてソイルセメント柱３の一軸圧縮強度を変更する、ソイルセメント柱３との一体性を高めるため芯材２にスタッドを設ける、芯材２の先端部に閉塞効果を高める部材を設ける等を実施する必要がないため、施工時における煩雑な作業を不要とし、また、経済的な負担も回避することが可能となる。 Therefore, in order to use the soil cement column wall 1 as a permanent pile, the uniaxial compressive strength of the soil cement column 3 is changed in accordance with the strength of the ground, and the core material 2 is improved in order to enhance the integrity with the soil cement column 3. It is not necessary to provide a stud on the core or to provide a member that enhances the blocking effect at the tip of the core material 2, thus eliminating the need for complicated work during construction and avoiding an economic burden. It becomes.
なお、本発明のソイルセメント柱列壁１よりなる杭の評価方法は、上記実施形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲で種々の変更が可能であることはいうまでもない。 In addition, the evaluation method of the pile which consists of the soil cement column wall 1 of this invention is not limited to the said embodiment, It goes without saying that various changes are possible in the range which does not deviate from the meaning of this invention. Nor.
１ ソイルセメント柱列壁
２ 芯材
２１ 先端部
３ ソイルセメント柱
４ 構造物
４１ 地下部
４２ 底盤
５ 支持層
６ 単杭
DESCRIPTION OF SYMBOLS 1 Soil cement pillar row wall 2 Core material 21 Tip part 3 Soil cement pillar 4 Structure 41 Basement part 42 Base board 5 Support layer 6 Single pile
Claims (1)
前記ソイルセメント柱列壁において、芯材が埋設された複数のソイルセメント柱各々を単杭とみなして、前記構造物の底盤下面高さを杭頭、前記芯材の先端部を杭先端部に設定し、
地盤から定まる極限支持力と杭材料の許容応力度から定まる極限支持力の両者を算定したうえで、いずれか小さい方の値を前記単杭の極限支持力として選定し、該単杭の許容鉛直支持力を算定することを特徴とするソイルセメント柱列壁よりなる杭の評価方法。 A method for evaluating a pile composed of soil cement column walls, in which a soil cement column wall that functions as a temporary retaining wall is used as a permanent pile of a structure in which an underground part is constructed using the temporary mountain retaining wall. ,
In the soil cement column wall, each of the plurality of soil cement columns in which the core material is embedded is regarded as a single pile, the bottom bottom surface height of the structure is the pile head, and the tip of the core material is the pile tip. Set,
After calculating both the ultimate bearing capacity determined from the ground and the ultimate bearing capacity determined from the allowable stress of the pile material, the smaller value is selected as the ultimate bearing capacity of the single pile, and the allowable vertical A method for evaluating piles made of soil cement column walls characterized by calculating bearing capacity.
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