JP3890427B2 - Improved column construction method for ground improvement - Google Patents
Improved column construction method for ground improvement Download PDFInfo
- Publication number
- JP3890427B2 JP3890427B2 JP19288197A JP19288197A JP3890427B2 JP 3890427 B2 JP3890427 B2 JP 3890427B2 JP 19288197 A JP19288197 A JP 19288197A JP 19288197 A JP19288197 A JP 19288197A JP 3890427 B2 JP3890427 B2 JP 3890427B2
- Authority
- JP
- Japan
- Prior art keywords
- excavation
- improved
- material liquid
- predetermined
- ground
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Description
【0001】
【発明の属する技術分野】
この発明は地盤改良柱の強度を均一化することを目的とした地盤改良における改良柱の築造工法に関する。
【0002】
【従来の技術】
従来地盤改良における改良柱は、固化材液を吐出し乍ら掘進するに当り、掘削スピードと、固化材液の吐出量を管理し乍ら改良柱を層状に築造している。
【0003】
【発明により解決すべき課題】
前記従来の築造方法によれば、同質地層(例えば砂層、粘土層)の場合には同質の改良柱が出来るが、異質地層が重なっている場合には、地層毎に改良柱の強度が異なる問題点があった。
【0004】
前記のように、改良柱に強度差があると、地震その他の横方向外力を受けた場合に、強度差の境目付近に応力が集中し、遂には挫屈破壊を生じる問題点がある。
【0005】
【課題を解決するための手段】
この発明は、改良柱の築造に際し、上下方向に亘って繰り返しを行うことにより、改良柱の局部的強度変化がなくなり、前記従来の問題点を解決したのである。
【0006】
即ちこの発明は、改良柱設置を決めた位置を定めたならば、該位置の地表から地中に向け固化材液を吐出し乍ら掘進し、所定の深度に達したならば、固化液の吐出を停止して、所定の長さに亘って繰り返えし、撹拌し乍ら所定の引上げ速度で掘削ロッドを引上げて改良柱を築造する方法であって、前記における所定の長さの繰り返えしは、前記改良柱の全長に亘って行なうと共に、砂質及び粘土質を含む異なる地層間をまたがるように行うことを特徴とし、 前記掘進中における固化材液の配合は、各地層毎に予め定めた配合とすることを特徴とした地盤改良における改良柱の築造工法である。また、前記において、所定の長さの繰り返えしは、固化液を吐出し乍ら行い、吐出する固化材液の配合は標準配合とすることを特徴とした地盤改良における改良柱の築造工法である。
【0007】
この発明における掘進速度は、地質によって異なるが、通常砂質土の場合には毎分1〜2mであり、粘土層の場合には毎分0.5〜1mであるが、設計基準強度(例えば毎平方糎当り10kgと同等又は以下)により異なる。前記における固化材液(例えばセメントミルク)の吐出量を一定にすれば、掘進速度が遅くなれば必然的に固化材液量の割合が多くなるが、掘進量に比例して固化材液量を定めることもできる。要は改良柱の強度をコントロールできれば良いことになる。
【0008】
この発明の地盤改良技術は、比較的軽量な建物の基礎、基盤の圧密沈下の防止、側方流動、滑り破壊の防止及び山留め背面の強化など、各種の目的に使用することができる。
【0009】
【発明の実施の形態】
この発明は、改良柱の強度を均一化する為に、掘進終了後、又は掘進中途において繰り返しを行うものである。
【0010】
前記繰り返しによって上下方向の強度の不均一性が改善される。
【0011】
【実施例1】
この発明の実施例を図面について説明する。図1において、先ず改良柱の築造位置に施工機を設置し、築造すべき改良柱の中心を定めて、これに掘削ロッドの中心を合わせる。ついで空掘部を所定の深度まで掘進したならば、掘削ロッドの下端から所定量の固化材液を吐出しながら所定の速度で改良柱となるべき部分を掘進する。掘進の深度が予め定めた深度に達したならば固化液の吐出を停止した後、前記空掘部の下端から、掘進下端までの全長に亘って繰り返す。具体的には掘削ロッドを回転し乍ら上下する。前記における繰り返しは、掘削ロッドを3〜6回全長に亘って上下して撹拌すれば、均一に混合することができる。前記繰り返しを終了したならば、掘削ロッドを所定の引上げ速度により撹拌し乍ら引上げれば、この場所の改良柱築造を完了する。一方固定材液は、セメント系固形材と、必要量の水とをミキサーに入れて十分混練し、流量計でチェックし乍ら所定の流速で供給する。
【0012】
前記において、定流量の場合には、掘削速度の調節によって掘削土と固化材液との混合比率を調節することができる。
【0013】
前記実施例は、改良柱の全長に亘って撹拌したが、異なる地層間をまたがるように繰り返したり、掘削の先端部を所定の長さに亘って繰り返すなどすればほぼ均等強さの改良柱を得ることができる。
【0014】
【実施例2】
この発明の実施例を図2、3、4、5に基づいて説明する。この発明を実施するには、掘削機8を所定の位置にセットし、掘削ロッド7の軸芯と、改良柱9の中心線とを一致させた後掘削を開始する。この発明に使用する掘削ロッド7は、外管1の内側に、内管2を挿通し、内管2の下端に掘削ヘッド3を固定する。前記外管1の下端に枠体5を固定して、枠体5に内管2の下端を挿通し、該部へ撹拌棒4、4を半径方向に穿設してある。図中6は枠体5を支持する為に内管2へ嵌めた環体であり、前記内管2の上端部は動力に接続してある(図示していない)。従って内管2と、掘削ヘッド3のみが回転し、外管1と枠体5とは回転しないので、掘削土は撹拌棒4、4で破砕されると共に、枠体5で破砕され、結局掘削土は十分な破砕と混練を受けて固化材液と混合し、均質な改良柱を形成することになる。
【0015】
この発明は、図4に示すように空掘部10、余盛部11及び改良部12に分離されている。また図5に示すように、掘進時は固化材液を吐出し、吐出停止後、所定の範囲13a(1部)、又は13b(全長)繰り返して掘削ロッドを引上げる。
【0016】
前記繰り返し時に、固化材液を若干吐出する場合もあるが、固化材液の全使用量をほぼ一定にすれば、均質の改良柱が出来ることになる。
【0017】
【発明の効果】
この発明によれば、掘進後、所定の長さに亘って繰り返しをするので、改良柱の強度を均等にする効果がある。
【0018】
従って地震その他によって改良柱へ横方向から外力が掛っても異なる地層の重なり部分から破壊するおそれがなく、地盤改良の効果を十分発揮することができる。
【図面の簡単な説明】
【図1】この発明の実施例のブロック図。
【図2】同じく施工状態を示す説明図。
(a)掘削前の状態。
(b)掘進開始の状態。
(c)予定深度まで掘進した状態。
(d)繰り返し後、掘削ロッドを引上げた状態。
【図3】同じく掘削ロッドの一部を省略した正面図。
【図4】同じく改良範囲を示す断面図。
【図5】同じく固化材液の吐出範囲を示す説明図。
【符号の説明】
1 外管
2 内管
3 掘削ヘッド
4 撹拌棒
5 枠体
6 環体
7 掘削ロッド
8 掘削機
9 改良柱
10 空掘部
11 余盛部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for constructing an improved column in ground improvement for the purpose of making the strength of the ground improved column uniform.
[0002]
[Prior art]
In the conventional improvement of the ground, the improved pillars are constructed in layers while controlling the excavation speed and the discharge amount of the solidified material liquid when the solidified material liquid is discharged and advanced.
[0003]
[Problems to be solved by the invention]
According to the conventional construction method, in the case of homogeneous strata (for example, sand layer, clay layer), improved columns of the same quality can be formed. However, when heterogeneous strata overlap, the strength of the improved columns varies from layer to layer. There was a point.
[0004]
As described above, when there is a difference in strength between the improved columns, there is a problem that stress is concentrated near the boundary of the strength difference and eventually causes a buckling failure when an earthquake or other lateral external force is applied.
[0005]
[Means for Solving the Problems]
The present invention, upon construction of the improved column by performing a back repeatedly over the vertical direction, there is no local intensity variation of the improved column is had to solve the above conventional problems.
[0006]
That the present invention, if determined the position decided improvement column installation, surface solidifying material liquid ejected to notwithstanding et excavation towards the ground from the position, if reached a predetermined depth of, solidifying solution Is a method of constructing an improved pillar by pulling up the excavating rod at a predetermined pulling speed while stirring and repeating the discharge for a predetermined length. repeated Kaee Mr. performs over the entire length of the modified column, characterized by performing to straddle between different strata containing sandy and clay, blending of solidifying material liquid during the excavation, the strata It is a construction method of an improved pillar in ground improvement characterized by having a predetermined composition every time . In addition, in the above, the predetermined length is repeated while discharging the solidified liquid, and the composition of the solidified material liquid to be discharged is a standard composition. It is .
[0007]
The excavation speed in the present invention differs depending on the geology, but is usually 1 to 2 m / min in the case of sandy soil, and 0.5 to 1 m / min in the case of clay layer, Equivalent to or less than 10kg per square kilometer. If the discharge amount of the solidifying material liquid (for example, cement milk) in the above is made constant, the ratio of the solidifying material liquid amount inevitably increases if the digging speed is slow, but the solidifying material liquid amount is proportional to the digging amount. It can also be determined. In short, it is only necessary to control the strength of the improved pillar.
[0008]
The ground improvement technology of the present invention can be used for various purposes such as relatively lightweight building foundations, prevention of consolidation settlement of foundations, lateral flow, prevention of slip breakage, and strengthening of the back of the retaining ring.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention, in order to equalize the intensity of the improved column, after excavation completed, or performs a repeatedly in excavation middle.
[0010]
Nonuniformity of vertical strength is improved by the repetition.
[0011]
[Example 1]
Embodiments of the present invention will be described with reference to the drawings. In FIG. 1, first, a construction machine is installed at the construction position of the improved pillar, the center of the improved pillar to be built is determined, and the center of the excavation rod is aligned with this. Next, when the hollow portion is dug to a predetermined depth, a portion to be an improved pillar is dug at a predetermined speed while discharging a predetermined amount of the solidified material liquid from the lower end of the excavating rod. After the depth of excavation has stopped discharge of the solidifying solution if reached predetermined depth from the lower end of the air-drilling unit, repeated over the entire length of up to excavation bottom. Specifically, the excavating rod rotates and moves up and down. Back repeatedly in the, if agitated up and down over the drill rod to 3-6 times the entire length, it can be uniformly mixed. Once completed the repetition, if Re stirred乍Ra pulling the drill rod by a predetermined pull rate, to complete the improvements pillar construction in this location. On the other hand, the fixing material liquid is supplied at a predetermined flow rate while thoroughly mixing with a cement-based solid material and a necessary amount of water in a mixer and checking with a flow meter.
[0012]
In the above, in the case of a constant flow rate, the mixing ratio of the excavated soil and the solidified material liquid can be adjusted by adjusting the excavation speed.
[0013]
The embodiment has been stirred over the entire length of the improving post, different or repeat to span between strata, almost uniform strength improvement Columns if such repeated over the tip of the excavation to a predetermined length Can be obtained.
[0014]
[Example 2]
An embodiment of the present invention will be described with reference to FIGS. In order to carry out the present invention, the
[0015]
As shown in FIG. 4, the present invention is separated into a hollow portion 10, a surplus portion 11, and an improved
[0016]
Sometimes the repetition, but sometimes slightly ejecting solidified material liquid, if a substantially constant total amount of solidifying material solution, so that the homogeneity of the improvements pillars can.
[0017]
【The invention's effect】
According to the present invention, after excavation, since the back repeatedly over a predetermined length, the effect of equalizing the intensity of the improved column.
[0018]
Therefore, even if an external force is applied from the lateral direction to the improved column due to an earthquake or the like, there is no possibility of breaking from the overlapping portions of different formations, and the effect of ground improvement can be sufficiently exhibited.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of the present invention.
FIG. 2 is an explanatory view showing a construction state in the same manner.
(A) State before excavation.
(B) State of starting excavation.
(C) The state where it has dug to the planned depth.
(D) after the repetition, it was pulling up the drill rod state.
FIG. 3 is a front view in which a part of the excavation rod is also omitted.
FIG. 4 is a cross-sectional view showing the improved range.
FIG. 5 is an explanatory view showing the discharge range of the solidifying material liquid.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer pipe 2
Claims (2)
前記における所定の長さの繰り返えしは、前記改良柱の全長に亘って行なうと共に、砂質及び粘土質を含む異なる地層間をまたがるように行うことを特徴とし、
前記掘進中における固化材液の配合は、各地層毎に予め定めた配合とすることを特徴とした地盤改良における改良柱の築造工法。Once determined the position decided improvement column installation, and notwithstanding et excavation ejecting solidified material liquid toward the ground from the surface of the position, if reached a predetermined depth of, stops the discharge of the solidifying solution A method of building an improved column by repeating a predetermined length and pulling up a drilling rod at a predetermined pulling speed while stirring .
The repetition of the predetermined length in the above is performed over the entire length of the improved pillar, and is performed so as to straddle different ground layers including sand and clay,
A method for constructing an improved pillar in ground improvement, characterized in that the composition of the solidifying material liquid during the excavation is a composition determined in advance for each stratum .
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19288197A JP3890427B2 (en) | 1997-07-17 | 1997-07-17 | Improved column construction method for ground improvement |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19288197A JP3890427B2 (en) | 1997-07-17 | 1997-07-17 | Improved column construction method for ground improvement |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH1136282A JPH1136282A (en) | 1999-02-09 |
JP3890427B2 true JP3890427B2 (en) | 2007-03-07 |
Family
ID=16298539
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP19288197A Expired - Lifetime JP3890427B2 (en) | 1997-07-17 | 1997-07-17 | Improved column construction method for ground improvement |
Country Status (1)
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JP (1) | JP3890427B2 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JP6824796B2 (en) * | 2017-03-27 | 2021-02-03 | 大成建設株式会社 | Ground improvement body construction method |
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1997
- 1997-07-17 JP JP19288197A patent/JP3890427B2/en not_active Expired - Lifetime
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JPH1136282A (en) | 1999-02-09 |
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