JP2007277862A - Soil improving method - Google Patents

Soil improving method Download PDF

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JP2007277862A
JP2007277862A JP2006103488A JP2006103488A JP2007277862A JP 2007277862 A JP2007277862 A JP 2007277862A JP 2006103488 A JP2006103488 A JP 2006103488A JP 2006103488 A JP2006103488 A JP 2006103488A JP 2007277862 A JP2007277862 A JP 2007277862A
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improvement
ground
mixing
soil
soft
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JP4822908B2 (en
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Kyo Nishio
経 西尾
Tatsuya Ito
達也 伊藤
Fumihiko Kimura
文彦 木村
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Onoda Chemico Co Ltd
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Onoda Chemico Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a soil improving method which is carried out by penetrating/pulling up a mixing and agitating device mounted on a base machine into/from soft ground via the ground surface to mix soft soil and hardening slurry with each other and agitate the resultant mixture, to thereby achieve soil improvement, wherein the method ensures the verticality of the mixing and agitating device and improved accuracy of a work location, and facilitates maintenance of the device. <P>SOLUTION: According to the soil improving method, the soft ground is hardened by a soil improving machine which is formed of construction equipment such as a backhoe as the base machine, and the vertically rotatable mixing and agitating device mounted on a distal end of the same. Specifically a mixing and agitating blade of the soil improving machine is penetrated into/pulled up from the soft ground via the ground surface to mix the soft soil and the hardener with each other and agitate the same, to thereby harden the soft ground. Herein before the improvement, the ground surface in an improvement target area is preliminarily excavated to form a dug groove, and the vertically rotatable mixing and agitating device is built in the dug groove. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、バックホウなどの建設機械をベースマシンとし、該ベースマシンのアームの先端に取り付けた混合攪拌装置を改良予定地盤面に対して鉛直方向に垂下させ、該垂下させた混合攪拌装置により軟弱地盤を地表面より掘削しながら土壌とセメント系固化材等を混合、攪拌して固化処理する地盤改良工法に関する。   In the present invention, a construction machine such as a backhoe is used as a base machine, and a mixing and stirring device attached to the tip of an arm of the base machine is suspended in a vertical direction with respect to a ground surface to be improved. The present invention relates to a ground improvement method in which soil and cement-based solidifying material are mixed and stirred for solidification while excavating the ground from the ground surface.

従来、この種の軟弱地盤改良工法の中で、主にセメント系固化材等を用いる改良工法において使用される地盤改良機は、図4に示すとおりバックホウ等の建設機械をベースマシンとし、該ベースマシン1のアーム6の先端に取り付けた鉛直方向に回動するロータリー式混合攪拌装置4の先端部に設けた上部吐出口7a及び下部吐出口7bより固化材スラリーを吐出しながら、該混合攪拌装置4を地表面8aから軟弱地盤8中に貫入・引き抜きを行いつつ軟弱土と固化材を混合攪拌し、軟弱地盤を固化処理する地盤改良工法が公知である。   Conventionally, in this kind of soft ground improvement method, the ground improvement machine mainly used in the improvement method using cement-based solidified material is a construction machine such as a backhoe as shown in FIG. While the solidified material slurry is discharged from the upper discharge port 7a and the lower discharge port 7b provided at the front end portion of the rotary mixing / stirring device 4 that is attached to the front end of the arm 6 of the machine 1 and rotates in the vertical direction, A ground improvement method is known in which soft soil and a solidifying material are mixed and stirred while penetrating 4 into and out of the soft ground 8 from the ground surface 8a to solidify the soft ground.

前記地盤改良工法の一般的な施工方法としては、改良するべき対象地盤の地表面に、消石灰等でのライン引き、あるいは目印としてポールを建てるなどして、一施工サイクルの区画ごとの作業領域の区割り表示をおこない、該区割り表示された改良対象地盤の地表面に対して、ベースマシン1のアーム6の先端に取り付けた混合攪拌装置4を垂下直立させ、該直立した混合攪拌装置4を地表面8aから地中に貫入しつつ、固化材スラリーを吐出し、混合攪拌装置4を上下させて貫入・引抜きを行うことにより、設計固化材添加量を混合し設計深度まで混合撹拌を行ったら、次の区画に移るという作業を繰り返して施工していた。
また、場合によっては貫入した混合攪拌装置を、そのまま改良領域の地盤中を前後に移動させて地盤改良を行う工法もあった。(例えば特許文献1、2、3参照。)
As a general construction method of the ground improvement method, a work area for each section of one construction cycle is established by drawing a line with slaked lime or building a pole as a mark on the ground surface of the target ground to be improved. The division stirring display 4 is performed, and the mixing and stirring device 4 attached to the tip of the arm 6 of the base machine 1 is suspended from the ground surface of the ground to be improved that is divided and displayed. After the solidified material slurry is discharged from the 8a through the ground and the mixing and agitating device 4 is moved up and down to penetrate and pull out, the design solidification material addition amount is mixed and mixed and stirred to the design depth. The work of moving to the section was repeated.
Moreover, depending on the case, there was also a method of improving the ground by moving the penetrating mixing and stirring device back and forth in the ground of the improved region as it is. (For example, see Patent Documents 1, 2, and 3.)

特開平10-204868号公報Japanese Patent Laid-Open No. 10-204868 特開2003-342947号公報Japanese Patent Laid-Open No. 2003-342947 特開2004-257206号公報JP 2004-257206 A

前記ベースマシンのアームの先端に混合攪拌装置を取り付けた地盤改良機は、出来る限り大きい改良深度を対象としていることから、地盤改良機の混合攪拌装置の重量が大きく、かつ、その躯体の高さはアームを上限近く上げたときの高さとほぼ等しいような機械構成になっている。
そして、ベースマシンによる混合攪拌装置は、貫入開始時では地盤抵抗がないことから、前記混合攪拌装置を改良予定地盤に貫入を開始するときに、混合攪拌装置がぶれるので地中への貫入時の鉛直性が損なわれ易いという欠点があった。
また、改良対象地盤の地表面に玉石、砂礫、障害物等が存在する場合には、地表面に垂直に立てた混合攪拌装置がそれらの障害物に当たり、混合攪拌装置の攪拌翼の回転方向と反対方向のぶれが大きく、一層鉛直精度は損なわれやすい状態となるという問題もあった。
また改良体のラップ施工が必要な場合にラップが確実に出来ない場合もあった。
The ground improvement machine in which the mixing and stirring device is attached to the tip of the arm of the base machine is intended for the improvement depth as large as possible, so the weight of the mixing and stirring device of the ground improvement machine is large and the height of the frame is high. Has a mechanical structure that is almost equal to the height when the arm is raised near the upper limit.
And since the mixing stirrer by the base machine has no ground resistance at the start of penetration, the mixing stirrer is shaken when the mixing stirrer starts penetrating into the ground to be improved. There was a drawback that the verticality was easily lost.
In addition, when cobbles, gravel, obstacles, etc. exist on the ground surface of the improvement target ground, the mixing stirrer standing upright to the ground surface hits these obstacles, and the rotation direction of the stirring blades of the mixing stirrer There was also a problem that the shake in the opposite direction was large and the vertical accuracy was more likely to be impaired.
Moreover, there was a case where wrapping could not be surely performed when lap construction of an improved body was required.

また、図4に示すように混合攪拌装置4の貫入開始時には、混合攪拌装置4の攪拌翼5が改良予定地盤8の地表面8aで矢印A方向に回転し、掘削貫入を開始するのであるが、その時、混合攪拌装置4の躯体4Bには、攪拌翼5が回転する矢印A方向と逆の矢印B方向に移動する力が働く。
そのため、改良開始時に混合攪拌装置4の攪拌翼5を設計改良位置に正しくセットしても、撹拌翼5が回転し始めると同時に混合撹拌装置4のセット位置は、攪拌翼5が回転する方向と逆方向の矢印B方向にずれるという問題があった。
In addition, as shown in FIG. 4, at the start of penetration of the mixing and stirring device 4, the stirring blade 5 of the mixing and stirring device 4 rotates in the direction of arrow A on the ground surface 8 a of the ground to be improved 8 to start excavation and penetration. At that time, a force that moves in the arrow B direction opposite to the arrow A direction in which the stirring blade 5 rotates acts on the casing 4B of the mixing and stirring device 4.
Therefore, even if the stirring blade 5 of the mixing and stirring device 4 is correctly set at the design improvement position at the start of the improvement, the setting position of the mixing and stirring device 4 is the same as the direction in which the stirring blade 5 rotates. There was a problem that the direction of the arrow B was reversed.

また、混合攪拌装置4をセットした後、回転翼5の回転貫入初期の時点では、地表面Sの土が攪拌翼5によって掻き揚げられ、その際土壌中に混ざっている砂利などが障害となり、更にぶれの原因ともなっていた。   In addition, after setting the mixing and stirring device 4, at the initial stage of the rotation penetration of the rotary blade 5, the soil on the ground surface S is scraped by the stirring blade 5, and gravel mixed in the soil becomes an obstacle at that time, It was also the cause of blurring.

また、前記のタイプの地盤改良施工に当たっては、固化材スラリー混合の場合、図5に示すとおり、混入した固化材スラリー量の体積相当分は、地表面8aに盛り上がり土(固化材混入泥土)10として生ずるため、設計改良深さが混合攪拌装置4の躯体4Bの上端縁部の近傍までの深さの改良施工をする場合、固化材スラリーが混入した固化材混入泥土10がアーム6先端のブラケット3部分、あるいはその上のシリンダー2部分にまで付着し、土粒子等がシリンダー2内に侵入することがあり、これらの部分が故障の原因になり易いという問題があった。   In addition, in the case of the above-mentioned ground improvement construction, in the case of mixing the solidifying material slurry, as shown in FIG. 5, the volume corresponding to the volume of the mixed solidifying material slurry is raised on the ground surface 8a (solidified material mixed mud) 10. Therefore, in the case where the design improvement depth is improved to the vicinity of the upper end edge of the casing 4B of the mixing and stirring device 4, the solidified material mixed mud 10 mixed with the solidified material slurry is the bracket at the tip of the arm 6. There is a problem that 3 parts or even the part of the cylinder 2 above it adheres and soil particles or the like may enter the cylinder 2 and these parts are likely to cause a failure.

本発明の地盤改良工法は、バックホウ等の建設機械をベースマシンとし、該ベースマシンのアームの先端に取り付けた鉛直方向に回転する混合攪拌装置の先端部より、固化材スラリーを吐出しながら、該混合攪拌装置を地表面から軟弱地盤中に貫入し、引き抜きを行いつつ軟弱土と固化材を混合攪拌し、軟弱地盤を固化処理する地盤改良工法において、改良前に改良対象領域部分の地表面を、混入する固化材スラリー相当の体積に当たる幅と深度か、又は、前記混合攪拌装置が貫入時にぶれないようガイドホール的な役割を果たす幅と深度か、又は、施工中の固化材混入泥土がベースマシンのアーム先端まで盛り上がらないような余裕を有する幅と深度の何れかから選択され、又は全てを満足する幅と深度まで、予め混合撹拌装置の略幅員まで溝状に掘削して前掘溝を形成し、該前堀溝内に鉛直方向に回動する混合攪拌装置を建て込み、地盤改良する地盤改良工法としたことである。   The ground improvement method of the present invention uses a construction machine such as a backhoe as a base machine, and discharges the solidified material slurry from the tip of a mixing and stirring device that rotates in the vertical direction attached to the tip of the arm of the base machine. In the ground improvement method where the mixing stirrer penetrates into the soft ground from the ground surface and the soft soil and solidified material are mixed and stirred while pulling out, and the soft ground is solidified, the ground surface of the area to be improved is improved before the improvement. The width and depth corresponding to the volume corresponding to the solidifying material slurry to be mixed, the width and depth that play the role of a guide hole so that the mixing and stirring device does not shake during penetration, or the solidifying material mixed mud during construction The width and depth of the mixing agitator are selected in advance so that they do not rise to the tip of the machine arm, or the width and depth satisfy all. To form a pre Homizo drilled in a groove shape, like an anchor mixing stirrer which rotates in the vertical direction in the front Horimizo is to have a soil improvement method of ground improvement.

本発明の地盤改良工法は上記のように、改良対象領域の地表面に前堀溝を形成する構成とし、該前堀溝内に建て込んだ混合攪拌装置の貫入時のぶれを前堀溝の側面で規制できるのでぶれを少なくすることができ、改良範囲の鉛直性の精度向上と施工位置セットの精度確保に大きく寄与することが出来る。
また、施工時に発生する盛り上がり泥土がブラケット、シリンダー部分に付着することを減少させることができるので、施工機械の作動性の向上・保守に寄与でき、もって、地盤改良の施工性を向上させることができる。
As described above, the ground improvement method of the present invention is configured to form a front moat groove on the ground surface of the area to be improved, and the shaking at the time of penetration of the mixing and stirring device built in the front moat groove is regulated by the side surface of the front moat groove. As a result, blurring can be reduced, which can greatly contribute to improving the accuracy of verticality in the improved range and ensuring the accuracy of the construction position set.
In addition, since it is possible to reduce the build-up mud generated during construction from adhering to the bracket and cylinder part, it is possible to contribute to the improvement and maintenance of the operability of construction machines, thereby improving the workability of ground improvement. it can.

なお、本発明において使用する混合撹拌装置を用いて地盤改良を行うと、その改良平面形状は矩形となる。そのため、100%より小さい改良率の設定、全面改良の場合の改良杭の重複が最小に抑えられる等の効果を奏することができる。   In addition, when ground improvement is performed using the mixing and stirring apparatus used in the present invention, the improved planar shape becomes a rectangle. Therefore, it is possible to achieve effects such as setting an improvement rate smaller than 100% and minimizing duplication of improved piles in the case of overall improvement.

以下、本発明の実施の形態を図面に基づいて説明する。
図1は、本発明の地盤改良工法に使用する地盤改良機の混合攪拌装置の先端攪拌翼を、改良対象地盤への貫入時前に、該地盤の地表面に別途用意したバックホウなどで予め掘削形成した前堀溝に、建て込んだ状態の概念図である。
また、図2は地盤改良機を平面的に表した図である。
図1〜2において、ベースマシン1はバックホウである。該ベースマシン1のアーム6の先端にはブラケット3が取り付けられ、該ブラケット3を介して混合攪拌装置4が装着されている。
また、混合攪拌装置4の先端部分には攪拌翼5が左右両側に取り付けられており、その近傍に、スラリー上部吐出口7a及びスラリー下部吐出口7bが配設されていて、前記地盤改良機による地盤改良は、平面的に図示した図2に示すように、改良対象領域に形成される地盤改良の平面改良形状が矩形状となるように構成されている。
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Fig. 1 shows excavation of the tip stirrer blade of the mixing stirrer of the ground improvement machine used in the ground improvement method of the present invention in advance with a backhoe separately prepared on the ground surface before entering the ground to be improved. It is a conceptual diagram of the state built in the formed front moat groove.
FIG. 2 is a plan view of the ground improvement machine.
1-2, the base machine 1 is a backhoe. A bracket 3 is attached to the tip of the arm 6 of the base machine 1, and a mixing and stirring device 4 is attached via the bracket 3.
Moreover, the stirring blade 5 is attached to the right and left both sides at the front end portion of the mixing and stirring device 4, and the slurry upper discharge port 7a and the slurry lower discharge port 7b are disposed in the vicinity thereof. The ground improvement is configured such that the planar improvement shape of the ground improvement formed in the improvement target region is rectangular as shown in FIG.

固化材スラリーを図示しないセメント系固化材スラリーを製造するスラリープラントより圧送し、スラリー下部吐出口7bから吐出し始めたのを確認したら、攪拌翼5を回転させながら混合攪拌装置4を地盤8に貫入させる。
そのとき貫入を容易にするために図示されていない空気圧縮機から配管され混合攪拌装置4の先端部近傍から圧縮空気を噴射する。
After confirming that the solidified material slurry was pumped from a slurry plant for producing a cement-based solidified material slurry (not shown) and started to be discharged from the slurry lower discharge port 7b, the mixing and stirring device 4 was moved to the ground 8 while rotating the stirring blade 5. Intrude.
At that time, in order to facilitate penetration, compressed air is injected from the vicinity of the tip of the mixing and stirring device 4 which is piped from an air compressor (not shown).

改良施工は、スラリー下部吐出口7bから固化材スラリーを吐出し、また圧縮空気を併用しながら、設計改良深度までほぼ定速で貫入して、設計深度にて先端処理を行いながら固化材スラリーの吐出口をスラリー下部吐出口7bからスラリー上部吐出口7aに変更し、ほぼ定速で混合攪拌装置4を引き上げる。
この引き上げが地表面8aまで到達したら、1サイクルの施工が終了することになる。後は、ベースマシン1を移動させ隣の施工区画に移り、前記サイクルを繰り返すことにより、改良施工を続ける。
In the improved construction, the solidified material slurry is discharged from the slurry lower discharge port 7b, and the compressed material slurry is penetrated at a substantially constant speed up to the design improvement depth while using compressed air. The discharge port is changed from the slurry lower discharge port 7b to the slurry upper discharge port 7a, and the mixing and stirring device 4 is pulled up at a substantially constant speed.
When this pulling reaches the ground surface 8a, one cycle of construction is completed. After that, the base machine 1 is moved to move to the next construction section, and the improvement construction is continued by repeating the cycle.

図3は、前記前堀溝9を横方向に連ねて長さh(n施工区画分)だけ掘削設置し、1施工区画の面積Aを施工中に盛り上がり土(固化材混入泥土)10が盛り上がりつつある状況である。この前堀溝9の断面形状(B×H)と、盛り上がり土(固化材混入泥土)10と、吐出した固化材スラリー量の関係については、段落番号18にて説明する。   FIG. 3 shows the excavation and installation of the front moat groove 9 in the lateral direction for a length h (n construction sections), and the soil A (solidified mud soil) 10 is rising during construction in the area A of one construction section. There is a situation. The relationship between the cross-sectional shape (B × H) of the pre-groove 9, the rising soil (solidified material mixed mud) 10, and the discharged amount of solidified material slurry will be described in paragraph number 18.

図4は前記の施工工程において、混合攪拌装置4が地中に貫入し始める時の状態を概念的に示す。
図4に示すように、混合攪拌装置4が地中に貫入し始める時、混合攪拌装置4は、ベースマシン1(バックホウ)が通常装備するバケットに比較して相当重量が大きくまた長さが長いから、アーム6先端のブラケット3が支点となるために必然的に、その先端の攪拌翼部分が回転する方向の逆の方向へ押し出され、施工位置がぶれやすく、回転トルクが大きければ大きいほど振れは大きい。
つまりこの貫入開始時には、攪拌翼5が地表面8aで回転するから、混合攪拌装置4には、攪拌翼5が回転するA方向と逆のB方向に移動する力が働き、その上ベースマシン1による貫入力は一番弱い状態であるから、施工位置のセット精度と一層鉛直精度は損なわれやすい状態となる。
そこで、改良箇所の地表面8aに図1に示すとおり前堀溝9を設けておけば、この前堀溝9が混合攪拌装置の貫入に当たってガイドホールのような役割を果たし、貫入時の鉛直精度の正確さ、次杭とのラップ精度の向上、施工方向性の管理のし易さ等の改善ができる。
FIG. 4 conceptually shows a state when the mixing and stirring device 4 starts to penetrate into the ground in the construction process.
As shown in FIG. 4, when the mixing and stirring device 4 starts to penetrate into the ground, the mixing and stirring device 4 has a considerably larger weight and a longer length than the bucket that the base machine 1 (backhoe) is normally equipped with. Therefore, since the bracket 3 at the tip of the arm 6 serves as a fulcrum, the stirring blade portion at the tip is inevitably pushed out in the direction opposite to the direction of rotation, and the construction position is likely to be shaken. Is big.
That is, since the stirring blade 5 rotates on the ground surface 8a at the start of the penetration, the mixing stirring device 4 has a force that moves in the B direction opposite to the A direction in which the stirring blade 5 rotates. Since the penetration input by is the weakest state, the setting accuracy of the construction position and the vertical accuracy are likely to be impaired.
Therefore, if a ground groove 8 is provided on the ground surface 8a of the improved portion as shown in FIG. 1, the front groove 9 functions as a guide hole when penetrating the mixing stirrer, and the vertical accuracy at the time of penetration is accurate. In addition, it is possible to improve the lap accuracy with the next pile and the ease of managing the construction direction.

また、前記の施工工程において、固化材スラリーを吐出しながら混合攪拌装置4を貫入及び引抜きを行う工程で、改良対象土と固化材スラリーの混合された固化材混入泥土10が改良箇所の地表面部分に盛り上がってくる。
図5は、設計改良長11が混合攪拌装置長さに近く混合攪拌装置が設計改良深度の下端に位置する場合で、固化材混入泥土10がブラケット3及びシリンダー2部分に付着している状態を示すが、この盛り上がる固化材混入泥土10の量は、当該区画に注入された固化材スラリー量と、混合攪拌装置4が占める体積相当量とほぼ等しい。
そこで、改良箇所の地表面8aに前堀溝9を設けておけば、固化材混入泥土10をこの前堀溝9部分に吸収することができ、ブラケット3及びシリンダー2部分に固化材混入泥土10が付着することを防ぐことができる。
Further, in the above construction process, the solidification material mixed mud 10 mixed with the soil to be improved and the solidifying material slurry is the ground surface of the improved portion in the step of penetrating and drawing out the mixing and stirring device 4 while discharging the solidifying material slurry. It rises to the part.
FIG. 5 shows a state where the design improvement length 11 is close to the mixing agitator length and the mixing agitator is located at the lower end of the design improvement depth, and the solidified material mixed mud 10 is attached to the bracket 3 and the cylinder 2 portion. As shown, the amount of the solidified material mixed mud 10 that rises is substantially equal to the amount of the solidified material slurry injected into the section and the volume equivalent amount occupied by the mixing and stirring device 4.
Therefore, if the front moat groove 9 is provided on the ground surface 8a of the improved portion, the solidified material mixed mud 10 can be absorbed by the front moat groove 9 portion, and the solidified material mixed mud soil 10 adheres to the bracket 3 and the cylinder 2 portion. Can be prevented.

図3は、前堀溝9の形状(幅:B(m)、深さ:H(m))と1区画当たりの盛り上がり土量S(m3)、改良対象土量V(m3)の関係を示す。
水固化材比(W/C)を1.0、固化材添加量をaw (t/m3)、1区画の改良平面形状面積A(m2)、改良杭数n(個)とすると、ほぼ次式の関係が成り立つ。
V=n×A×L(m3)・・・・・・・・・・・(1)
S≒V×(a/0.76)×(1.0〜1.2)・・・(2)
B×H×h≧S・・・・・・・・・・・・(3)
前堀溝9の形状は、上式を満足するように現場条件に合わせて適宜設定すればよい。
また、改良工程が終了する時点では、改良対象領域の土は撹乱され固化材スラリーと混合されて泥土化しているため、混合撹拌装置4には、鉛直方向のロータリー式回転によって、貫入時より更に大きくぶれる力が加わるが、先行掘削した前堀溝9のために抑えられ振れが生じない。
Fig. 3 shows the relationship between the shape (width: B (m), depth: H (m)) of the pre-drilling groove 9, the amount of raised soil S (m 3 ) per section, and the amount of soil V (m 3 ) to be improved Indicates.
Assuming that the water-solidifying material ratio (W / C) is 1.0, the amount of solidifying material added is a w (t / m 3 ), the improved planar shape area A (m 2 ) of one section, and the number of improved piles n (pieces), The following relationship holds.
V = n x A x L (m 3 ) (1)
S ≒ V × ( aw / 0.76) × (1.0 ~ 1.2) (2)
B × H × h ≧ S (3)
The shape of the front moat groove 9 may be appropriately set according to the field conditions so as to satisfy the above formula.
Further, at the time when the improvement process is completed, the soil in the improvement target region is disturbed and mixed with the solidifying material slurry to become mud, so that the mixing and agitating device 4 is further rotated by a rotary rotation in the vertical direction from the time of penetration. Although a large swaying force is applied, it is suppressed due to the pre-drilling pre-drilling groove 9 and no runout occurs.

また、本発明の改良工法に用いられる混合攪拌装置を、バックホウのアームの先端に取付け例を示したが、これに限定されるものでなく、三点支持式杭打機のリーダーに混合攪拌装置を装着し、昇降させながら混合攪拌しても良い。   In addition, the mixing and stirring device used in the improved construction method of the present invention is shown as an example of attachment to the tip of the arm of the backhoe. However, the present invention is not limited to this, and the mixing and stirring device is used as a leader of a three-point support pile driver. May be mixed and stirred while moving up and down.

なお、本地盤改良機による地表面からの地盤改良(浅層〜中層地盤改良)では、混合攪拌装置の貫入にあたり、固化材スラリーの吐出時期を地表面から任意の深さより開始し、引き抜き時に前記の任意の深度で停止することにより、空打ち部(地表面から任意の深さの固化材未混入部)を作ることが出来る。   In the ground improvement from the ground surface by this ground improvement machine (shallow layer to middle layer ground improvement), when penetrating the mixing and stirring device, the discharge timing of the solidified slurry starts from an arbitrary depth from the ground surface, By stopping at an arbitrary depth, it is possible to make an empty portion (a solidified material-unmixed portion at an arbitrary depth from the ground surface).

施工1サイクル平面積2.25m2(□1.5m×1.5m)設計改良深度8.0m、セメント系固化材添加量100kg/m3、水固化材比1.0、固化材比重ρ=3.12、注入スラリー体積は8.0m貫入時に設計量の1/2仮定して約1.2m3、また、混合攪拌装置の占める概略体積は1.2m3(8.0m貫入時)であったので、1サイクル当たりの溝掘削深度は、(1.2m3+1.2m3)÷2.25m2≒1.0mと計算された。
また、改良工程終了時には、注入スラリー体積は2.4m3であるから同じく溝掘削深度は2.4m3÷2.25m2≒1.0mであるので、施工対象区画を幅1.5m、深さ1.0mの溝状に掘削して地盤改良工を施工した。なお深さHは固化材添加量に応じ自在に設定すればよい。
なお、図3に施工状況の概念図を示す。
Construction 1-cycle flat area 2.25m 2 (□ 1.5m × 1.5m) Depth of design improvement 8.0m, cement solidification material addition amount 100kg / m 3 , water solidification material ratio 1.0, solidification material specific gravity ρ = 3.12, injection slurry volume is 8.0m penetration when designing the amount of 1/2 assuming about 1.2 m 3, also, since the outline volume occupied by the mixing and stirring apparatus was 1.2 m 3 (at the time 8.0m penetration), trenching depth per cycle (1.2m 3 + 1.2m 3 ) ÷ 2.25m 2 ≒ 1.0m
At the end of the improvement process, the injection slurry volume is 2.4 m 3 , so the groove excavation depth is 2.4 m 3 ÷ 2.25 m 2 ≒ 1.0 m. Therefore, the construction target section is 1.5 m wide and 1.0 m deep. The ground improvement work was carried out by excavating it into the shape. The depth H may be set freely according to the amount of solidifying material added.
In addition, the conceptual diagram of a construction condition is shown in FIG.

施工した結果、貫入開始時のぶれも少なく、設計貫入深度貫入時(貫入深度最大時)に盛り上がる固化材混入泥土10がほぼ前堀溝9を満たし、ブラケット3及びシリンダー2部分に固化材混入泥土10が付着することを防ぐことができた。   As a result of the construction, there is little blurring at the start of penetration, and the solidified material mixed mud 10 that rises when the design penetration depth penetrates (when the penetration depth is maximum) almost fills the front moat groove 9, and the bracket 3 and the cylinder 2 portion contain solidified material mixed mud 10 Was able to be prevented.

本発明は、ベースマシンに取り付けた混合攪拌装置により軟弱地盤を固化処理する地盤改良工の鉛直施工精度向上、施工機械保守の容易性に貢献できる。   INDUSTRIAL APPLICABILITY The present invention can contribute to improvement in vertical construction accuracy of a ground improvement work for solidifying soft ground by a mixing and stirring device attached to a base machine, and ease of maintenance of construction machinery.

本発明の工法に使用する地盤改良機の混合撹拌装置先端部が改良対象地盤への貫入時に、前堀溝に挿入された状態の概念図。The conceptual diagram of the state by which the mixing stirring apparatus front-end | tip part of the ground improvement machine used for the construction method of this invention was inserted in the front moat groove at the time of penetration into the improvement object ground. 前記地盤改良機を平面的に表した図。The figure which represented the said ground improvement machine planarly. 本発明の施工状態を示す概念図。The conceptual diagram which shows the construction state of this invention. 従来施工時の混合攪拌装置が地中に貫入し始める時の状態の概念図。The conceptual diagram of a state when the mixing and stirring apparatus at the time of conventional construction begins to penetrate into the ground. 従来の工法における混合撹拌装置の長さと設計改良長がほぼ等しい場合の最深部改良状態を示す図。The figure which shows the deepest part improvement state in case the length of the mixing stirring apparatus in the conventional construction method and design improvement length are substantially equal.

符号の説明Explanation of symbols

1 ベースマシン
2 シリンダー
3 ブラケット
4 混合攪拌装置
4B 躯体
5 攪拌翼
6 アーム
7a スラリー上部吐出口
7b スラリー下部吐出口
8 地盤
8a 地表面
9 前堀溝
10 盛り上がり土(固化材混入泥土)
11 設計改良深さ
A 改良体平面形状面積
B 前堀溝の幅
H 前堀溝の深度
1 Base machine 2 Cylinder 3 Bracket 4 Mixing and stirring device 4B Housing
5 Stirring blade 6 Arm 7a Slurry upper discharge port 7b Slurry lower discharge port 8 Ground 8a Ground surface
9 Maebori Groove 10 Swelling soil (solidified material mixed mud)
11 Depth of design improvement A Plane shape area of improved body B Width of foregro groove H Depth of foregroove

Claims (4)

バックホウ等の建設機械をベースマシンとしてその先端に鉛直方向に回動する混合攪拌装置を装着した地盤改良機の混合攪拌翼を、地表面から軟弱地盤中に貫入・引き抜きを行いつつ軟弱土と固化材を混合攪拌し、軟弱地盤を固化処理する地盤改良工法において、改良前に改良対象領域の地表面を予め掘削して前堀溝を形成し、該前掘溝内に鉛直方向に回動する混合攪拌装置を建て込み地盤改良をすることを特徴とする地盤改良工法。   The mixing stirrer of a ground improvement machine equipped with a mixing stirrer that pivots vertically at the tip of a construction machine such as a backhoe is solidified with soft soil while penetrating into and pulling out the soft ground from the ground surface. In the ground improvement method in which the material is mixed and agitated and the soft ground is solidified, before the improvement, the ground surface of the improvement target area is excavated in advance to form a front moat groove, and mixed in the vertical direction in the front groove A ground improvement method characterized by building a stirring device and improving the ground. 改良前の改良対象領域の地表面に形成される前堀溝の形状が、混合撹拌装置の幅員と略同じ幅員からなる掘削溝であることを特徴とする請求項1記載の地盤改良工法。   2. The ground improvement method according to claim 1, wherein the shape of the front moat formed on the ground surface of the improvement target area before the improvement is an excavation groove having a width substantially the same as the width of the mixing and stirring device. 改良前の改良対象領域の地表面に形成される前堀溝が、混入する固化材スラリーの略体積相当量に当たる幅と深度からなることを特徴とする請求項1記載の地盤改良工法。   2. The ground improvement method according to claim 1, wherein the front moat formed on the ground surface of the improvement target region before the improvement has a width and a depth corresponding to an approximately volume equivalent amount of the solidified slurry to be mixed. 改良対象領域に形成される地盤改良の平面改良形状が矩形状であることを特徴とする請求項1記載の地盤改良工法。   The ground improvement construction method according to claim 1, wherein the planar improvement shape of the ground improvement formed in the improvement target region is rectangular.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009221770A (en) * 2008-03-18 2009-10-01 Onoda Chemico Co Ltd Soil improving machine and soil improving method
CN110004934A (en) * 2019-04-11 2019-07-12 中国葛洲坝集团第一工程有限公司 Foundation excavation of silt excavation construction method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0874245A (en) * 1994-09-02 1996-03-19 Elf:Kk Continuous underground wall construction process
JPH1068124A (en) * 1996-08-28 1998-03-10 Hitachi Constr Mach Co Ltd Soft soil improvement machine, stirring machine, and soft soil improvement method
JPH11256564A (en) * 1998-03-13 1999-09-21 Tenox Corp Continuous two-plane soil improvement body and construction method therefor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0874245A (en) * 1994-09-02 1996-03-19 Elf:Kk Continuous underground wall construction process
JPH1068124A (en) * 1996-08-28 1998-03-10 Hitachi Constr Mach Co Ltd Soft soil improvement machine, stirring machine, and soft soil improvement method
JPH11256564A (en) * 1998-03-13 1999-09-21 Tenox Corp Continuous two-plane soil improvement body and construction method therefor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009221770A (en) * 2008-03-18 2009-10-01 Onoda Chemico Co Ltd Soil improving machine and soil improving method
CN110004934A (en) * 2019-04-11 2019-07-12 中国葛洲坝集团第一工程有限公司 Foundation excavation of silt excavation construction method
CN110004934B (en) * 2019-04-11 2019-12-13 中国葛洲坝集团第一工程有限公司 Excavation construction method for silt foundation pit

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