JP4188032B2 - Ground improvement method - Google Patents
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- JP4188032B2 JP4188032B2 JP2002249633A JP2002249633A JP4188032B2 JP 4188032 B2 JP4188032 B2 JP 4188032B2 JP 2002249633 A JP2002249633 A JP 2002249633A JP 2002249633 A JP2002249633 A JP 2002249633A JP 4188032 B2 JP4188032 B2 JP 4188032B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、地盤の確認方法、地盤のデータ整理方法、地盤の改良方法及び改良された地盤に関するものである。
【０００２】
【従来の技術】
地盤の液状化を防止するため、地盤を改良する工法が各種提案されている。それらの方法として、地盤を全面的に固化する全体固化法、壁状、スラブ状、杭状等の改良体を構築する部分改良工法がある。部分改良工法として、ＴＯＦＴ或いはＪＡＭＰＳ等が知られている。
【０００３】
また、部分改良工法として、特開平１１−１３１４６７号公報には、薬液注入による砂地盤の固化改良工法が記載されている。
この公報には、地盤内に薬液を注入し、球状の改良体を構築し、その注入率を変化させることが記載されている。
【０００４】
【発明が解決しようとする課題】
しかしながら、前記公報に記載された方法では、改良体自体の強度についてはふれられていない。また、振動台内部に改良体を構築し、振動させるので、実験設備が大がかりなものとなる。
【０００５】
本発明は、このような問題を鑑みてなされたもので、その目的とするところは、改良体自体の強度を考慮し、簡単な実験設備で地盤の確認を行い、地盤を改良する改良方法等を提供することにある。
【００１１】
本発明は、地盤の部分改良を行う地盤の改良方法であって、前記地盤の試料を採取し、採取した試料に対して、室内配合試験を行い、改良材の種類及び濃度と一軸圧縮強度または比抵抗値との関係を求める工程（ａ）と、目標液状化安全率と想定する地震力とを定め、目標液状化強度比を定める工程（ｂ）と、部分改良試料の繰返し非排水試験を行い、一軸圧縮強度または比抵抗値と改良率と液状化強度比との関係を求める工程（ｃ）と、前記工程（ｃ）で求めた関係を用いて、前記工程（ｂ）で定めた前記目標液状化強度比に対する、目標改良率と目標一軸圧縮強度または目標比抵抗値とを求める工程（ｄ）と、前記工程（ｄ）で求めた前記目標一軸圧縮強度または前記目標比抵抗値と、前記工程（ａ）で求めた関係を用いて、前記目標一軸圧縮強度または前記目標比抵抗値に対応する改良材の種類及び濃度とを定める工程（ｅ）と、前記地盤に対して、前記工程（ｄ）で求めた前記目標改良率になるように、前記工程（ｅ）で求めた種類と濃度の改良材を注入する工程（ｆ）と、前記注入された地盤からの採取土の一軸圧縮強度または比抵抗値の測定を行う工程（ｇ）と、前記工程（ｇ）で測定した一軸圧縮強度または比抵抗値が、前記工程（ｄ）で定めた前記目標一軸圧縮強度または前記目標比抵抗値となるまで、前記工程（ｆ）から前記工程（ｇ）までを繰り返す工程（ｈ）とを具備することを特徴とする地盤の改良方法。
【００１２】
【発明の実施の形態】
以下、図面に基づいて本発明の実施の形態を詳細に説明する。図１は、本実施の形態に係る地盤の改良方法の手順を示すフローチャートである。
【００１３】
まず、改良を行おうとする地盤の試料を採取する（ステップ１０１）。
採取された試料に対して、室内配合試験を行い、改良材仕様（改良材の種類や濃度等）と、一軸圧縮強度ｑｕの関係を求める（ステップ１０２）。
【００１４】
ここで改良材とは、セメント系固化材、薬液、ポリマー等である。ステップ１０１で採取された試料に対して、これらの改良材を配合して、その種類や濃度を変化させ、一軸圧縮強度ｑｕを求め、改良材仕様と一軸圧縮強度ｑｕの関係を求める。
【００１５】
次に、構造物や地盤の設計を行い、目標とする液状化安全率ＦＬ０を求め、想定する地震力を定め、目標とする液状化強度比ＲＬ０を定める（ステップ１０３）。
ここで、ＦＬ：液状化安全率、Ｒ：液状化強度比、Ｌ：地震時に地盤に作用する最大せん断応力比とすると、
ＦＬ＝Ｒ／Ｌ ……（１）
の関係がある。
設計上の地震を想定し、地震時に地盤に作用する最大せん断応力比Ｌおよび、目標とする液状化安全率ＦＬｏを決定すると、（１）式より目標とする液状化強度比Ｒ０が定められる。
【００１６】
次に、部分改良試料の繰り返し非排水試験を行い、一軸圧縮強度ｑｕ、改良率、液状化強度比Ｒの関係を求める（ステップ１０４）。
繰り返し非排水試験とは、例えば繰り返し非排水三軸試験、ねじりせん断試験、単純せん断試験等である。
部分改良試料とは、ステップ１０１で採取された試料に対して、改良材を部分的に充填した試料である。
なお、改良率＝（改良体の体積）／（元の試料全体の体積）である。
【００１７】
以下、非排水三軸試験を用いた例を具体的に説明する。
図２は、薬液注入装置２０１を示す図、図３は、供試体２０３のＡ−Ａ断面図である。
モールド２０２上に載荷板２０７が置かれる。モールド２０２内には、注入管２０９により薬液の注入が可能であり、モールド２０２内には、最終的に供試体を包み込むラバーメンブレン２１１が負圧にてモールド２０２内面に密着される。図２において、２１３はＯ−リング（オーリング）、２１５は下部ペデスタルである。
【００１８】
モールド２０２内に試料２０４（例えば、砂）を入れて、原地盤密度（ここでは一例として相対密度が５０％）となるように締め固めたのち、モールド２０２にて側面を拘束した状態で、原地盤で想定される所定の有効上載圧（例えば９８ｋＮ／ｍ２）を載荷する。
【００１９】
ここで飽和地盤を作成する場合には、事前にモールド２０２内に水を満たしておけばよい。
このようにして、モールド２０２内に供試体２０３を構築したのち、注入管２０９から例えばシリカゾル系の薬液を注入する。注入箇所を変えることにより、例えば１２球（＝４段×３球）の改良体２０５を接球状に作成する。
【００２０】
注入が終了すると、上載圧を載荷した状態で供試体２０３を１５時間静置させる。この間に、薬液は硬化する。
図３は、このときの改良体２０５の断面を示すもので、２１０は注入管２０９による挿入穴である。
以上により、原地盤での実際の注入状況をできるだけ近い状態で、室内で模擬することが可能である。
【００２１】
次に、上載圧を除荷した後（サンプリングによる応力開放を模擬）、供試体２０３を三軸試験装置にセットし、繰り返し非排水三軸試験を行う
【００２２】
図４、図５は、この繰り返し非排水三軸試験の試験結果を示すもので、図４は、繰り返しに伴い、例えば両振幅軸ひずみＤＡが５％に至るときの、繰り返しせん断応力比ＳＲと繰り返し回数の関係を示し、図５は、繰り返し中に発生する最大せん断ひずみγｍａｘと、繰り返しせん断後に排水したときの体積ひずみεｖとの関係を示す図である。
尚、図４において、液状化を示す指標として想定する任意の両振幅軸ひずみの他、過剰間隙水圧比等を用いることができる。
【００２３】
図４に示されるように、部分改良土は接球状でも未改良砂に比べ、繰り返しせん断抵抗が大きくなっている。
例えば、改良体の一軸圧縮強度ｑｕが１８０ｋＮ／ｍ２ 、改良率４２％の部分改良土は、一軸圧縮強度ｑｕが１１８ｋＮ／ｍ２の全体改良に比較的近い液状化抵抗特性を有することがわかる。
【００２４】
また、同じ改良率であれば、改良体の一軸圧縮強度ｑｕが大きくなるほど、繰り返しせん断抵抗が大きくなる傾向を確認できた。
また、図５に示すように、部分改良土の体積ひずみεｖは、１０％前後のせん断ひずみレベルまで最大せん断ひずみγｍａｘと一意で線形な関係を有し、未改良砂或いは一軸圧縮強度ｑｕ＝１１８ｋＮ／ｍ２の全体改良土の特性と概ね一致することが分かった。
【００２５】
そして、改良率、改良体強度を種々変更して試験を多数行い、改良体の一軸圧縮強度ｑｕ、改良地盤の改良率、液状化強度比Ｒの関係を求める。
図６は、一軸圧縮強度ｑｕ、改良率、液状化強度比Ｒの関係を示すグラフである。
尚、一軸圧縮強度ｑｕは別途一軸圧縮試験を行い求められる。また、液状化強度比Ｒは、図４に示すグラフにおいて、繰り返し回数が２０回の時の繰り返しせん断応力比ＳＲの値である。
【００２６】
次に、目標の液状化強度比Ｒ０に対する目標部分改良率、目標一軸圧縮強度ｑｕ０、改良材仕様を定める（ステップ１０５）。尚、本明細書内において、部分改良率は改良率と同義として用いる。
即ち、図６に示すグラフにおいて、目標の液状化強度比Ｒ０を与えると、一軸圧縮強度ｑｕと、改良率の組み合わせが定まる。
【００２７】
例えば、Ｒ０＝０．３の場合、図６に示すＲ＝０．３で示す直線が定まり、目標一軸圧縮強度ｑｕ０、目標部分改良率の組み合わせが決まる。
そして目標部分改良率を５０％とすれば、対応する目標一軸圧縮強度ｑｕ０ （ここでは、ｑｕ０ ＝２１０ｋｐａ）が定まる。
【００２８】
また、ステップ１０２で改良材仕様と一軸圧縮強度ｑｕの関係が求められているので、目標一軸圧縮強度ｑｕ０が定まると、改良材仕様（改良材の種類、濃度等）も定まる。
このようにして、目標の液状化安全率ＦＬ０に対する目標部分改良率、目標一軸圧縮強度ｑｕ０、改良材仕様が定められる。
以上は、実験室で行われる処理である。
【００２９】
次に、目標部分改良率、改良材仕様で実地盤に対して注入を行う（ステップ１０６）。ステップ１０６以後は、実地盤に対して実際に注入を行い、地盤改良を行う場合の処理である。
例えば、目標部分改良率を５０％とし、ステップ１０５で定まった改良材を用いて実地盤に注入を行う。
【００３０】
そして、改良された実地盤（改良地盤）の品質確認を行う（ステップ１０７）。
改良地盤の品質が改良地盤の目標品質を満足するまでステップ１０６、１０７、１０８の処理を繰り返す（ステップ１０８）。
【００３１】
品質確認方法としては種々の方法がある。例えば、改良地盤に対してチェックボーリングを行う場合の品質確認法として次の方法が考えられる。
不撹乱試料を採取し、一軸圧縮試験を行い、採取土の一軸圧縮強度ｑｕを確認する。すなわち、採取土(改良土)の一軸圧縮強度ｑｕが、目標一軸圧縮強度ｑｕ０より大きければ、改良地盤の品質が改良地盤の目標品質を満足したとする。
【００３２】
また、不撹乱試料の状況あるいは、一軸圧縮強度により、深さ方向の改良体の出来形を確認する。これらの管理項目が目標値を満足すれば、改良地盤の品質が改良地盤の目標品質を満足したとする。
その他の方法として、例えば、電気比抵抗トモグラフィーを利用する方法も挙げられる。この場合、改良体の強度は、地盤の比抵抗値で、出来形は比抵抗値の分布性状で確認できる。
すなわち、図１において一軸圧縮強度に代えて比抵抗値を用いる。
【００３３】
図７は、改良体３０３が設けられた地盤３０１を示す図である。
地盤３０１内に球状の改良体３０３が所定個数設けられ、この地盤３０１上に建物３０５が構築される。
【００３４】
尚、改良体３０３の形状は、球状以外の形状でも良い。例えば、立方体形状や直方体形状等の改良体を地盤３０１内に構築しても良い。
また、図７の例では、各改良体３０３は接触していないが、部分改良率が高い場合、各改良体が接触することもある。
【００３５】
このように、本実施の形態によれば、改良体自体の強度を考慮して、地盤改良を行うことが出来る。また、三軸試験装置のような簡単な実験装置で試験を行うことでできる。
【００３６】
【発明の効果】
以上、詳細に説明したように本発明によれば、改良体自体の強度を考慮し、簡単な実験設備で部分改良地盤の液状化対策効果を確認をした上で、地盤を改良することができる。
【図面の簡単な説明】
【図１】 地盤の改良方法の手順を示すフローチャート
【図２】 薬液注入装置２０１を示す図
【図３】 図２の供試体２０３の断面を示す図
【図４】 繰り返し回数と繰り返しせん断応力比ＳＲの関係を示す図
【図５】 最大せん断ひずみγｍａｘと繰り返しせん断後の体積ひずみεｖの関係を示す図
【図６】 改良率と一軸圧縮強度ｑｕと液状化安全率ＲＬとの関係を示す図
【図７】 改良体３０３が設けられた地盤３０１を示す図
【符号の説明】
２０１………三軸試験装置
２０３………供試体
２０５………改良体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground confirmation method, ground data arrangement method, ground improvement method, and improved ground.
[0002]
[Prior art]
In order to prevent liquefaction of the ground, various methods for improving the ground have been proposed. As these methods, there are a total solidification method for solidifying the ground entirely, and a partial improvement method for constructing an improved body such as a wall shape, a slab shape, and a pile shape. As a partial improvement method, TOFT or JAMPS is known.
[0003]
Further, as a partial improvement method, Japanese Patent Application Laid-Open No. 11-131467 describes a sand ground solidification improvement method by chemical injection.
This publication describes that a chemical solution is injected into the ground, a spherical improved body is constructed, and the injection rate is changed.
[0004]
[Problems to be solved by the invention]
However, in the method described in the publication, the strength of the improved body itself is not mentioned. Moreover, since the improved body is built and vibrated inside the shaking table, the experimental equipment becomes large.
[0005]
The present invention has been made in view of such problems, and an object, taking into account the strength of the improved body itself, confirms the ground with simple laboratory equipment, improved process for improving the soil, etc. Is to provide.
[0011]
The present invention is a ground improvement method for partial improvement of the ground, the ground sample is collected, an indoor blending test is performed on the collected sample, and the type and concentration of the improved material and the uniaxial compressive strength or The step (a) for determining the relationship with the specific resistance value, the target liquefaction safety factor and the assumed seismic force, the step (b) for determining the target liquefaction strength ratio, and the repeated undrained test of the partially improved sample Performing the step (c) for determining the relationship between the uniaxial compressive strength or the specific resistance value, the improvement rate, and the liquefaction strength ratio, and using the relationship determined in the step (c), the step (b) A step (d) for obtaining a target improvement rate and a target uniaxial compressive strength or a target specific resistance value with respect to a target liquefaction strength ratio; and the target uniaxial compressive strength or the target specific resistance value obtained in the step (d); Using the relationship obtained in the step (a), the target The step (e) of determining the type and concentration of the improvement material corresponding to the compressive strength or the target specific resistance value, and for the ground, the target improvement rate determined in the step (d) A step (f) of injecting an improved material of the type and concentration obtained in step (e), a step (g) of measuring the uniaxial compressive strength or specific resistance value of the collected soil from the injected ground, and Until the uniaxial compressive strength or specific resistance value measured in the step (g) becomes the target uniaxial compressive strength or the target specific resistance value determined in the step (d), the steps (f) to (g) And a step (h) of repeating the above.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart showing the procedure of the ground improvement method according to the present embodiment.
[0013]
First, a ground sample to be improved is collected (step 101).
Against samples collected performs indoor compounding test, the modifying material specifications (improvement agent type and concentration, etc.) to determine the relationship between the uniaxial compressive strength q u (step 102).
[0014]
Here, the improving material is a cement-based solidifying material, a chemical solution, a polymer, or the like. The sample taken in
[0015]
Next, the structure and the ground are designed, the target liquefaction safety factor F L0 is obtained, the assumed seismic force is determined, and the target liquefaction strength ratio R L0 is determined (step 103).
Where F L : liquefaction safety factor, R: liquefaction strength ratio, L: maximum shear stress ratio acting on the ground during an earthquake,
FL = R / L (1)
There is a relationship.
Assuming a design earthquake and determining the maximum shear stress ratio L acting on the ground during the earthquake and the target liquefaction safety factor FLo, the target liquefaction strength ratio R 0 is determined from equation (1). .
[0016]
Next, a repeated non-drainage test of the partially improved sample is performed, and the relationship between the uniaxial compressive strength q u , the improvement rate, and the liquefaction strength ratio R is obtained (step 104).
The repeated undrained test is, for example, a repeated undrained triaxial test, a torsional shear test, a simple shear test, or the like.
The partially improved sample is a sample obtained by partially filling the improved material with respect to the sample collected in
Note that the improvement rate = (volume of the improved body) / (volume of the original whole sample).
[0017]
Hereinafter, an example using the undrained triaxial test will be specifically described.
FIG. 2 is a view showing the chemical liquid injector 201, and FIG. 3 is a cross-sectional view taken along line AA of the specimen 203.
A loading plate 207 is placed on the mold 202. A chemical solution can be injected into the mold 202 through an injection tube 209. In the mold 202, a rubber membrane 211 that finally wraps the specimen is brought into close contact with the inner surface of the mold 202 under a negative pressure. In FIG. 2, 213 is an O-ring (O-ring), and 215 is a lower pedestal.
[0018]
A sample 204 (for example, sand) is put in the mold 202 and compacted to a raw ground density (in this case, the relative density is 50% as an example). A predetermined effective upper pressure (for example, 98 kN / m 2 ) assumed on the ground is loaded.
[0019]
Here, when creating a saturated ground, the mold 202 may be filled with water in advance.
In this way, after the specimen 203 is built in the mold 202, for example, a silica sol chemical solution is injected from the injection tube 209. By changing the injection location, for example, 12 balls (= 4 stages × 3 balls) of the improved body 205 are formed in contact with the ball.
[0020]
When the injection is completed, the specimen 203 is allowed to stand for 15 hours in a state where the upper pressure is loaded. During this time, the chemical solution is cured.
FIG. 3 shows a cross section of the improved body 205 at this time, and 210 is an insertion hole for the injection tube 209.
By the above, it is possible to simulate the actual injection situation in the raw ground in the room as close as possible.
[0021]
Next, after unloading the mounting pressure (simulating stress release by sampling), the specimen 203 is set in a triaxial test apparatus, and repeated undrained triaxial tests are performed.
4 and 5 show the test results of this repeated undrained triaxial test. FIG. 4 shows the repeated shear stress ratio SR when both amplitude axis strains DA reach 5%, for example. FIG. 5 is a diagram showing the relationship between the maximum shear strain γmax generated during repetition and the volume strain εv when drained after repeated shearing.
In FIG. 4, an excess pore water pressure ratio or the like can be used in addition to arbitrary both-axis amplitude strain assumed as an index indicating liquefaction.
[0023]
As shown in FIG. 4, even when the partially improved soil is in contact with a spherical shape, the repeated shear resistance is larger than that of unmodified sand.
For example, the uniaxial compressive strength q u is 180kN / m 2 of the improved body, improvement of 42% partially modified soil may be uniaxial compressive strength q u has a relatively close liquefaction resistance characteristic throughout improvement of 118kN / m 2 I understand.
[0024]
Moreover, if the improvement rate was the same, it was confirmed that the shear resistance increased repeatedly as the uniaxial compressive strength q u of the improved body increased.
Further, as shown in FIG. 5, the volume strain εv of the partially improved soil has a unique and linear relationship with the maximum shear strain γmax up to a shear strain level of about 10%, and unmodified sand or uniaxial compressive strength q u = It was found that the characteristics of the whole improved soil of 118 kN / m 2 were almost the same.
[0025]
A number of tests are performed with various improvements of the improvement rate and the strength of the improved body, and the relationship between the uniaxial compressive strength q u of the improved body, the improvement rate of the improved ground, and the liquefaction strength ratio R is obtained.
FIG. 6 is a graph showing the relationship between the uniaxial compressive strength q u , the improvement rate, and the liquefaction strength ratio R.
The uniaxial compression strength q u can be obtained by separately conducting a uniaxial compression test. The liquefaction strength ratio R is the value of the repeated shear stress ratio SR when the number of repetitions is 20 in the graph shown in FIG.
[0026]
Next, a target partial improvement rate, a target uniaxial compressive strength q u0 , and improvement material specifications for the target liquefaction strength ratio R 0 are determined (step 105). In the present specification, the partial improvement rate is used synonymously with the improvement rate.
That is, in the graph shown in FIG. 6, when the target liquefaction strength ratio R 0 is given, the combination of the uniaxial compression strength q u and the improvement rate is determined.
[0027]
For example, when R 0 = 0.3, a straight line represented by R = 0.3 shown in FIG. 6 is determined, and a combination of the target uniaxial compression strength q u0 and the target partial improvement rate is determined.
And if the target portion improvement rate of 50%, (in this case, q u0 = 210 kPa) corresponding target uniaxial compressive strength q u0 is determined.
[0028]
Further, since the relationship between the improved material specification and the uniaxial compressive strength q u is obtained in
In this way, the target portions improvement rate for liquefaction safety factor F L0 goal, target uniaxial compressive strength q u0, defined improved material specification.
The above is the process performed in the laboratory.
[0029]
Next, the actual ground is injected with the target partial improvement rate and the improved material specification (step 106). Step 106 and subsequent steps are processing when the actual ground is injected and the ground is improved.
For example, the target partial improvement rate is set to 50%, and the improvement material determined in
[0030]
Then, the quality of the improved actual ground (improved ground) is confirmed (step 107).
[0031]
There are various quality confirmation methods. For example, the following method can be considered as a quality confirmation method when performing check boring on the improved ground.
An undisturbed sample is collected, a uniaxial compression test is performed, and the uniaxial compression strength q u of the collected soil is confirmed. That is, if the uniaxial compressive strength q u of the collected soil (improved soil) is larger than the target uniaxial compressive strength q u0, it is assumed that the quality of the improved ground satisfies the target quality of the improved ground.
[0032]
In addition, the shape of the improved body in the depth direction is confirmed based on the state of the undisturbed sample or the uniaxial compressive strength. If these management items satisfy the target value, it is assumed that the quality of the improved ground satisfies the target quality of the improved ground.
Other methods include, for example, a method using electrical resistivity tomography. In this case, the strength of the improved body can be confirmed by the specific resistance value of the ground, and the finished shape can be confirmed by the distribution of the specific resistance value.
That is, the specific resistance value is used instead of the uniaxial compressive strength in FIG.
[0033]
FIG. 7 is a diagram showing the ground 301 provided with the
A predetermined number of
[0034]
Note that the shape of the
Moreover, in the example of FIG. 7, each
[0035]
Thus, according to the present embodiment, the ground can be improved in consideration of the strength of the improved body itself. In addition, the test can be performed with a simple experimental apparatus such as a triaxial test apparatus.
[0036]
【The invention's effect】
As described above in detail, according to the present invention, the strength of the improved body itself is taken into consideration, and the ground can be improved after confirming the liquefaction countermeasure effect of the partially improved ground with simple experimental equipment. .
[Brief description of the drawings]
FIG. 1 is a flowchart showing the procedure of a ground improvement method. FIG. 2 is a diagram showing a chemical solution injector 201. FIG. 3 is a cross-sectional view of a specimen 203 in FIG. 2. FIG. Fig. 5 is a graph showing the relationship between SR. Fig. 5 is a graph showing the relationship between maximum shear strain γmax and volume strain ε v after repeated shearing. Fig. 6 is a relationship between improvement rate, uniaxial compressive strength q u and liquefaction safety factor RL. FIG. 7 is a diagram showing the ground 301 provided with the
201 ... Triaxial test apparatus 203 ... Specimen 205 ... Improved body
Claims (2)
前記地盤の試料を採取し、採取した試料に対して、室内配合試験を行い、改良材の種類及び濃度と一軸圧縮強度との関係を求める工程（ａ）と、
目標液状化安全率と想定する地震力とを定め、目標液状化強度比を定める工程（ｂ）と、
部分改良試料の繰返し非排水試験を行い、一軸圧縮強度と改良率と液状化強度比との関係を求める工程（ｃ）と、
前記工程（ｃ）で求めた関係を用いて、前記工程（ｂ）で定めた前記目標液状化強度比に対する、目標改良率と目標一軸圧縮強度とを求める工程（ｄ）と、
前記工程（ｄ）で求めた前記目標一軸圧縮強度と、前記工程（ａ）で求めた関係を用いて、前記目標一軸圧縮強度に対応する改良材の種類及び濃度とを定める工程（ｅ）と、
前記地盤に対して、前記工程（ｄ）で求めた前記目標改良率になるように、前記工程（ｅ）で求めた種類と濃度の改良材を注入する工程（ｆ）と、
前記注入された地盤からの採取土の一軸圧縮強度の測定を行う工程（ｇ）と、
前記工程（ｇ）で測定した一軸圧縮強度が、前記工程（ｄ）で定めた前記目標一軸圧縮強度となるまで、前記工程（ｆ）から前記工程（ｇ）までを繰り返す工程（ｈ）とを
具備することを特徴とする地盤の改良方法。A ground improvement method for performing partial ground improvement,
Collecting a sample of the ground, performing an indoor blending test on the collected sample, and obtaining a relationship between the type and concentration of the improved material and the uniaxial compressive strength (a);
A step (b) of determining a target liquefaction safety factor and an assumed seismic force, and determining a target liquefaction strength ratio;
A step (c) of repeatedly performing a non-drainage test on the partially improved sample to obtain a relationship between the uniaxial compressive strength, the improvement rate, and the liquefaction strength ratio;
Using the relationship obtained in the step (c), a step (d) for obtaining a target improvement rate and a target uniaxial compressive strength with respect to the target liquefaction strength ratio determined in the step (b);
(E) determining the type and concentration of the improved material corresponding to the target uniaxial compressive strength using the target uniaxial compressive strength obtained in the step (d) and the relationship obtained in the step (a); ,
A step (f) of injecting the improvement material of the type and concentration obtained in the step (e) so as to achieve the target improvement rate obtained in the step (d) with respect to the ground;
A step (g) of measuring the uniaxial compressive strength of the collected soil from the injected ground;
Repeating the step (f) to the step (g) until the uniaxial compressive strength measured in the step (g) reaches the target uniaxial compressive strength determined in the step (d). A ground improvement method characterized by comprising.
前記地盤の試料を採取し、採取した試料に対して、室内配合試験を行い、改良材の種類及び濃度と比抵抗値との関係を求める工程（ａ）と、
目標液状化安全率と想定する地震力とを定め、目標液状化強度比を定める工程（ｂ）と、
部分改良試料の繰返し非排水試験を行い、比抵抗値と改良率と液状化強度比との関係を求める工程（ｃ）と、
前記工程（ｃ）で求めた関係を用いて、前記工程（ｂ）で定めた前記目標液状化強度比に対する、目標改良率と目標比抵抗値とを求める工程（ｄ）と、
前記工程（ｄ）で求めた前記目標比抵抗値と、前記工程（ａ）で求めた関係を用いて、前記目標比抵抗値に対応する改良材の種類及び濃度とを定める工程（ｅ）と、
前記地盤に対して、前記工程（ｄ）で求めた前記目標改良率になるように、前記工程（ｅ）で求めた種類と濃度の改良材を注入する工程（ｆ）と、
前記注入された地盤からの採取土の比抵抗値の測定を行う工程（ｇ）と、
前記工程（ｇ）で測定した比抵抗値が、前記工程（ｄ）で定めた前記目標比抵抗値となるまで、前記工程（ｆ）から前記工程（ｇ）までを繰り返す工程（ｈ）とを
具備することを特徴とする地盤の改良方法。A ground improvement method for performing partial ground improvement,
Collecting a sample of the ground, performing an indoor blending test on the collected sample, and obtaining a relationship between the type and concentration of the improved material and the specific resistance value (a);
A step (b) of determining a target liquefaction safety factor and an assumed seismic force, and determining a target liquefaction strength ratio;
A step (c) of repeatedly performing a non-drainage test on the partially improved sample to obtain a relationship between the specific resistance value, the improvement rate, and the liquefaction strength ratio;
Using the relationship obtained in the step (c), a step (d) for obtaining a target improvement rate and a target specific resistance value for the target liquefaction strength ratio determined in the step (b);
(E) determining the type and concentration of the improved material corresponding to the target specific resistance value using the target specific resistance value obtained in the step (d) and the relationship obtained in the step (a); ,
A step (f) of injecting the improvement material of the type and concentration obtained in the step (e) so as to achieve the target improvement rate obtained in the step (d) with respect to the ground;
A step (g) of measuring a specific resistance value of the collected soil from the injected ground;
Repeating the step (h) from the step (f) to the step (g) until the specific resistance value measured in the step (g) reaches the target specific resistance value determined in the step (d). A ground improvement method characterized by comprising.
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| JP4625273B2 (en) * | 2004-06-10 | 2011-02-02 | 東亜建設工業株式会社 | Determination method of chemical concentration used to prevent liquefaction by chemical injection and stabilization treatment method of earth and sand by chemical injection |
| JP4500231B2 (en) * | 2005-08-02 | 2010-07-14 | 国立大学法人京都大学 | Method for determining strength and thickness of improved layer of backfill sand by chemical injection and experimental apparatus used therefor |
| JP6165194B2 (en) * | 2015-05-29 | 2017-07-19 | 五洋建設株式会社 | Ground improvement method by chemical injection and ground improvement optimization method |
| JP6475111B2 (en) * | 2015-07-03 | 2019-02-27 | 小野田ケミコ株式会社 | Chemical injection method |
| KR101662167B1 (en) * | 2016-05-16 | 2016-10-04 | (주)우진이앤씨 | Sample Extracting Apparatus for Improving Ground and Method for Checking Quality of The Improving Ground using The Same |
| JP6385018B2 (en) * | 2017-05-01 | 2018-09-05 | 五洋建設株式会社 | Ground improvement method by chemical injection and ground improvement optimization method |
| JP7080087B2 (en) * | 2018-03-30 | 2022-06-03 | 太平洋セメント株式会社 | Ridge creation method |
| JP7696563B2 (en) * | 2021-07-09 | 2025-06-23 | 戸田建設株式会社 | Method for evaluating the effect of ground improvement using chemical grouting method |
| JP7696565B2 (en) * | 2021-08-17 | 2025-06-23 | 戸田建設株式会社 | Method for evaluating the effect of ground improvement using chemical grouting method |
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