JP2019035208A - Strength estimation method of cement improved soil - Google Patents
Strength estimation method of cement improved soil Download PDFInfo
- Publication number
- JP2019035208A JP2019035208A JP2017155672A JP2017155672A JP2019035208A JP 2019035208 A JP2019035208 A JP 2019035208A JP 2017155672 A JP2017155672 A JP 2017155672A JP 2017155672 A JP2017155672 A JP 2017155672A JP 2019035208 A JP2019035208 A JP 2019035208A
- Authority
- JP
- Japan
- Prior art keywords
- cement
- diffraction
- improved soil
- strength
- compressive strength
- 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.)
- Granted
Links
- 239000002689 soil Substances 0.000 title claims abstract description 135
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000004568 cement Substances 0.000 title claims abstract description 38
- 238000002441 X-ray diffraction Methods 0.000 claims abstract description 54
- 230000006835 compression Effects 0.000 claims abstract description 28
- 238000007906 compression Methods 0.000 claims abstract description 28
- 238000010276 construction Methods 0.000 claims description 8
- 238000012669 compression test Methods 0.000 description 22
- 239000000463 material Substances 0.000 description 19
- 239000011162 core material Substances 0.000 description 11
- 238000012360 testing method Methods 0.000 description 9
- 229910052602 gypsum Inorganic materials 0.000 description 6
- 239000010440 gypsum Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 5
- 229910052791 calcium Inorganic materials 0.000 description 5
- 239000011575 calcium Substances 0.000 description 5
- 238000002474 experimental method Methods 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 239000010802 sludge Substances 0.000 description 5
- 238000000465 moulding Methods 0.000 description 4
- 238000003908 quality control method Methods 0.000 description 4
- 239000002893 slag Substances 0.000 description 4
- 238000007711 solidification Methods 0.000 description 4
- 230000008023 solidification Effects 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 3
- 239000004927 clay Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229910001653 ettringite Inorganic materials 0.000 description 3
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000011398 Portland cement Substances 0.000 description 2
- 229910000278 bentonite Inorganic materials 0.000 description 2
- 239000000440 bentonite Substances 0.000 description 2
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 150000004683 dihydrates Chemical class 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000004480 active ingredient Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 239000010801 sewage sludge Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000019086 sulfide ion homeostasis Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Images
Landscapes
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
Abstract
Description
本発明は、セメント改良土の圧縮強度をＸ線回折法により推定する方法に関する。 The present invention relates to a method for estimating the compressive strength of cement-modified soil by an X-ray diffraction method.
従来、地盤改良工法として、原位置で改良対象土にセメント系固化材を混合し、強制的に混合攪拌を行い、目標の圧縮強度が発生するまで養生し、強固な地盤を造成する工法が公知である。目標の圧縮強度が得られたかは、チェックボーリングにより改良体コアを採取し、たとえば、JIS A1216：2009(土の一軸圧縮試験方法)規格に基づいて、一軸圧縮試験用の供試体を作製し、一軸圧縮強度試験を行って確認する。 Conventionally, as a ground improvement method, there is a well-known method that mixes cement-based solidified material with the soil to be improved in-situ, forcibly mixes and stirs, cures until the target compressive strength is generated, and creates a solid ground It is. Whether or not the target compressive strength was obtained, the improved core was collected by check boring. For example, based on JIS A1216: 2009 (uniaxial compression test method for soil), a specimen for uniaxial compression test was prepared, Confirm by conducting a uniaxial compressive strength test.
特許文献１は、浚渫土・製鋼スラグ混合材から採取した試料中から蛍光Ｘ線分析によりカルシウム含有量を測定し、そのカルシウム含有量の測定値を、予め求めておいた浚渫土・製鋼スラグ混合材のカルシウム含有量と一軸圧縮強さ等の強度との相関に照らし合わせて強度発現を予測し、その予測値が目標強度を達成しているか否かの判定をする浚渫土・製鋼スラグ混合材の品質管理方法を開示する。
In
特許文献２は、普通ポルトランドセメントと、ペーパースラッジ灰と、廃石膏ボードから採取した二水石膏と、を含んでなる地盤改良用固化材を開示する。かかる固化材では廃石膏と汚泥等を混合すると硫化水素が発生し、この発生の抑制を確認するために、各供試体を粉砕した試料に対してＸ線回折装置を用いて試料内の結晶の同定を行い、その結果、地盤改良用固化材を特定の配合割合にすることで、廃石膏に含まれるすべての硫酸カルシウムが、エトリンガイトの生成に消費され、汚泥等に混合しても硫化水素が発生する恐れがないことが確認された。
セメント系固化材と改良対象土との混合攪拌による地盤改良の場合、圧縮強度の確認のため改良地盤から改良体コアを採取し、一軸圧縮試験用の供試体を成形等により作製し、試験室等において一軸圧縮試験機により一軸圧縮試験を行わなければならず、強度確認工程に多くの時間と手間を要している。また、改良体コアの採取中や採取後にコアが破損すると、一軸圧縮強度試験を行うことができず、圧縮強度の確認ができなくなってしまう。また、たとえば、JIS A1216規格にしたがって、直径5cm、高さ10cmの円柱状に成形された一軸圧縮試験用の供試体を養生毎に3本用意し、一軸圧縮試験を行うが、一本当たり200g程度（1g/cm3として）の試料が必要となる。 In the case of ground improvement by mixing and stirring the cement-based solidified material and the soil to be improved, an improved core is collected from the improved ground to confirm the compressive strength, and a specimen for uniaxial compression testing is prepared by molding, etc. In such a case, a uniaxial compression test must be performed by a uniaxial compression tester, and much time and labor are required for the strength confirmation process. In addition, if the core is damaged during or after collection of the improved body core, the uniaxial compressive strength test cannot be performed and the compressive strength cannot be confirmed. In addition, for example, according to JIS A1216 standard, three specimens for uniaxial compression test molded in a cylindrical shape with a diameter of 5 cm and a height of 10 cm are prepared for each curing, and a uniaxial compression test is performed. A sample of the order (as 1 g / cm 3 ) is required.
また、海底における地盤改良の場合、改良地盤から改良体コアを採取するが、水底の高圧環境下から強度試験を行う常圧環境への移動時にコアの破損が生じやすく、供試体の成形が困難になってしまう。かかる問題は特に深海の海底の場合にいっそう生じやすい。 In addition, in the case of ground improvement on the sea floor, the improved core is collected from the improved ground, but the core is easily damaged when moving from the high pressure environment of the water bottom to the normal pressure environment where the strength test is performed, making it difficult to form the specimen. Become. Such problems are more likely to occur especially in the deep sea.
特許文献１は、浚渫土・製鋼スラグ混合材の一軸圧縮強度を蛍光Ｘ線分析により測定したカルシウム含有量の測定値から予測するもので、浚渫土・製鋼スラグ混合材におけるカルシウム含有量と一軸圧縮強度との相関関係を前提にしたものである。
特許文献２は、普通ポルトランドセメントと、ペーパースラッジ灰と、廃石膏ボードから採取した二水石膏と、を含んでなる地盤改良用固化材における硫化水素発生等の対策に関するものであり、改良土の一軸圧縮強度は特に問題にされていない。
本発明は、上述のような従来技術の問題に鑑み、セメント改良土の圧縮強度の確認を簡単な工程でより少ない試料で行うことができるセメント改良土の強度推定方法を提供することを目的とする。 The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a method for estimating the strength of cement-improved soil, which can confirm the compressive strength of the cement-improved soil with a smaller number of samples in a simple process. To do.
上記目的を達成するため本発明者は、鋭意実験・検討の結果、セメント改良土から採取した試料についてＸ線回折を行ったところ、特定の回折角（２θ）に回折ピークが存在し、その回折ピーク強度がセメント改良土の一軸圧縮強度と関連性を有することを見いだし、本発明に至ったものである。 In order to achieve the above object, the present inventor conducted X-ray diffraction on a sample collected from cement-improved soil as a result of diligent experiments and examinations. As a result, a diffraction peak exists at a specific diffraction angle (2θ). It has been found that the peak strength is related to the uniaxial compressive strength of the cement-improved soil, and the present invention has been achieved.
すなわち、上記目的を達成するための第１のセメント改良土の強度推定方法は、セメント改良土の圧縮強度をＸ線回折法により推定する方法であって、推定対象のセメント改良土から採取した試料についてＸ線回折を行うことで、回折ピーク強度およびその回折角（２θ）を測定するステップと、予め得たセメント改良土の圧縮強度と前記回折角（２θ）における回折ピーク強度との相関関係に基づいて前記測定された回折ピーク強度からセメント改良土の圧縮強度を求めるステップと、を有し、前記求めた圧縮強度を前記推定対象のセメント改良土の圧縮強度と推定する。 That is, the first method for estimating the strength of cement-improved soil for achieving the above object is a method for estimating the compressive strength of cement-improved soil by the X-ray diffraction method, and is a sample collected from the target cement-improved soil. X-ray diffraction is performed to measure the diffraction peak intensity and the diffraction angle (2θ), and the correlation between the compression strength of the cement-improved soil obtained in advance and the diffraction peak intensity at the diffraction angle (2θ). And determining the compressive strength of the cement-improved soil from the measured diffraction peak intensity based on the measured compressive strength, and estimating the determined compressive strength as the compressive strength of the cement-improved soil to be estimated.
第１のセメント改良土の強度推定方法によれば、推定対象のセメント改良土から採取した試料についてＸ線回折を行い、回折ピーク強度とその回折角（２θ）を測定し、一方、セメント改良土の圧縮強度とその回折角（２θ）における回折ピーク強度との相関関係を予め得ておき、かかる相関関係に基づいて測定された回折ピーク強度からセメント改良土の圧縮強度を求め、その求めた圧縮強度を推定対象のセメント改良土の圧縮強度と推定するので、推定対象のセメント改良土の供試体による一軸圧縮試験が不要であり、セメント改良土の圧縮強度の確認を簡単な工程で行うことができ、また、Ｘ線回折は1g以下の微量の試料で済み、一軸圧縮試験と比べると、かなり少ない試料で行うことができる。なお、前記回折ピーク強度は、バックグラウンドの影響を排除するために補正されている。 According to the first method for estimating the strength of cement-improved soil, X-ray diffraction is performed on a sample collected from the target cement-improved soil, and the diffraction peak intensity and diffraction angle (2θ) are measured. Is obtained in advance, and the compression strength of the cement-improved soil is obtained from the diffraction peak intensity measured based on the correlation, and the obtained compression is obtained. Since the strength is estimated as the compressive strength of the cement-improved soil to be estimated, a uniaxial compression test using the specimen of the cement-improved soil to be estimated is unnecessary, and the compressive strength of the cement-improved soil can be confirmed in a simple process. In addition, X-ray diffraction can be performed with a very small amount of sample of 1 g or less, and can be performed with a considerably small number of samples as compared with the uniaxial compression test. The diffraction peak intensity is corrected in order to eliminate the influence of background.
上記第１のセメント改良土の強度推定方法において、前記回折角（２θ）は11.6〜11.7°および／または9.0〜9.1°である。かかる回折角（２θ）における回折ピーク強度とセメント改良土の圧縮強度との間には相関関係がある。 In the first method for estimating the strength of the cement-improved soil, the diffraction angle (2θ) is 11.6 to 11.7 ° and / or 9.0 to 9.1 °. There is a correlation between the diffraction peak intensity at the diffraction angle (2θ) and the compressive strength of the cement-improved soil.
上記目的を達成するための第２のセメント改良土の強度推定方法は、セメント改良土の圧縮強度をＸ線回折法により推定する方法であって、セメント改良土から採取した試料について圧縮強度を測定する第１ステップと、前記セメント改良土から採取した試料についてＸ線回折を行うことで回折ピーク強度およびその回折角（２θ）を測定する第２ステップと、前記測定された圧縮強度および回折ピーク強度に基づいて前記圧縮強度と関連性を有する回折ピーク強度およびその回折角（２θ）を特定する第３ステップと、前記セメント改良土の圧縮強度と前記特定した回折角（２θ）における回折ピーク強度との相関関係を得る第４ステップと、推定対象のセメント改良土から採取した試料についてＸ線回折を行うことで前記特定した回折角（２θ）における回折ピーク強度を測定する第５ステップと、前記圧縮強度と前記特定した回折角（２θ）における回折ピーク強度との相関関係に基づいて前記測定された回折ピーク強度からセメント改良土の圧縮強度を求める第６ステップと、を有し、前記求めた圧縮強度を前記推定対象のセメント改良土の強度と推定する。 The second method for estimating the strength of cement-improved soil to achieve the above object is a method for estimating the compressive strength of cement-improved soil by the X-ray diffraction method, and measures the compressive strength of a sample collected from the cement-improved soil. A first step of measuring a diffraction peak intensity and a diffraction angle (2θ) thereof by performing X-ray diffraction on a sample collected from the cement-improved soil, and the measured compressive strength and diffraction peak intensity. A third step of specifying a diffraction peak intensity and a diffraction angle (2θ) related to the compressive strength based on the above, a compressive strength of the cement-modified soil, and a diffraction peak intensity at the specified diffraction angle (2θ) The above-mentioned diffraction angle (by the X-ray diffraction on the sample collected from the cement-improved soil to be estimated, The fifth step of measuring the diffraction peak intensity at θ) and the compression of the cement-improved soil from the measured diffraction peak intensity based on the correlation between the compressive strength and the diffraction peak intensity at the specified diffraction angle (2θ) A sixth step for obtaining strength, and the obtained compressive strength is estimated as the strength of the cement-improved soil to be estimated.
第２のセメント改良土の強度推定方法によれば、第１ステップで測定された圧縮強度および第２ステップで測定された回折ピーク強度に基づいて圧縮強度と関連性を有する回折ピーク強度およびその回折角（２θ）を特定し、セメント改良土の圧縮強度とその特定した回折角（２θ）における回折ピーク強度との相関関係を得る一方、推定対象のセメント改良土から採取した試料についてＸ線回折を行い、その特定した回折角（２θ）における回折ピーク強度を測定し、圧縮強度と特定した回折角（２θ）における回折ピーク強度との相関関係に基づいてその測定された回折ピーク強度からセメント改良土の圧縮強度を求め、その求めた圧縮強度を推定対象のセメント改良土の圧縮強度と推定するので、推定対象のセメント改良土の供試体による一軸圧縮試験が不要であり、セメント改良土の圧縮強度の確認を簡単な工程で行うことができ、また、Ｘ線回折は1g以下の微量の試料で済み、一軸圧縮試験と比べると、かなり少ない試料で行うことができる。なお、前記回折ピーク強度は、バックグラウンドの影響を排除するために補正されている。 According to the second method for estimating the strength of the cement-improved soil, the diffraction peak intensity related to the compressive strength based on the compressive strength measured in the first step and the diffraction peak intensity measured in the second step, and The folding angle (2θ) is specified, and the correlation between the compressive strength of the cement improved soil and the diffraction peak intensity at the specified diffraction angle (2θ) is obtained. And measure the diffraction peak intensity at the specified diffraction angle (2θ), and based on the correlation between the compressive strength and the diffraction peak intensity at the specified diffraction angle (2θ), the cement improved soil The compressive strength of the cement-improved soil to be estimated is estimated as the compressive strength of the target cement-improved soil. The uniaxial compression test is unnecessary, and the compressive strength of the cement-improved soil can be confirmed with a simple process. Also, X-ray diffraction requires only a small amount of sample of 1 g or less, which is considerably less than the uniaxial compression test. Can be performed on the sample. The diffraction peak intensity is corrected in order to eliminate the influence of background.
上記第１および第２のセメント改良土の強度推定方法において、前記推定対象のセメント改良土に関するＸ線回折を前記推定対象のセメント改良土の施工現場において行うことが好ましい。試料のＸ線回折を推定対象のセメント改良土の施工現場において行うことで、セメント改良土の圧縮強度の確認を迅速に行うことができ、たとえば、品質管理等に迅速に反映させることができる。なお、この場合、ポータブルタイプのＸ線回折装置を用いることが好ましい。 In the first and second cement-improved soil strength estimation methods, it is preferable to perform X-ray diffraction relating to the estimation-target cement-improved soil at a construction site of the estimation-target cement-improved soil. By performing X-ray diffraction of the sample at the construction site of the cement-improved soil to be estimated, the compressive strength of the cement-improved soil can be quickly confirmed, and can be reflected quickly in quality control, for example. In this case, it is preferable to use a portable type X-ray diffractometer.
また、第２のセメント改良土の強度推定方法において圧縮強度を変えた複数のセメント改良土について前記第１および第２ステップを実行することが好ましい。なお、セメント改良土の圧縮強度は、養生期間や混合割合を変えることで変えることができる。 In addition, it is preferable to execute the first and second steps for a plurality of cement-improved soils having different compressive strengths in the second cement-improved soil strength estimation method. In addition, the compressive strength of cement improved soil can be changed by changing the curing period and the mixing ratio.
また、前記第１ステップで圧縮強度を測定した試料を用いて前記第２ステップのＸ線回折を行うことができる。 Further, the X-ray diffraction of the second step can be performed using the sample whose compressive strength is measured in the first step.
上記第１および第２のセメント改良土の強度推定方法において、前記推定対象のセメント改良土は、常圧環境下のみならず高圧環境下で施工されたものであってもよい。たとえば、深海の海底で施工された改良地盤から採取した試料についてＸ線回折により、その圧縮強度を推定できるので、高圧環境から常圧環境に戻した際に試料破損が生じても圧縮強度推定が可能である。 In the first and second cement-improved soil strength estimation methods, the estimation target cement-improved soil may be constructed not only under normal pressure but also under high pressure. For example, compressive strength can be estimated by X-ray diffraction for samples collected from improved ground constructed on the deep sea floor, so that even if sample damage occurs when returning from a high-pressure environment to a normal-pressure environment, it is possible to estimate the compressive strength. Is possible.
本発明のセメント改良土の強度推定方法によれば、セメント改良土の圧縮強度の確認を簡単な工程でより少ない試料で行うことができる。 According to the strength estimation method for cement-improved soil of the present invention, the compressive strength of cement-improved soil can be confirmed with a smaller number of samples in a simple process.
以下、本発明を実施するための形態について図面を用いて説明する。図１は本実施形態によるセメント改良土の強度推定方法の各ステップＳ０１〜Ｓ０８を説明するためのフローチャートである。図２は図１のステップＳ０１でセメント改良土の一軸圧縮強度を測定する一軸圧縮強度試験機の一例を示す概略図である。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a flowchart for explaining steps S01 to S08 of the cement-improved soil strength estimation method according to this embodiment. FIG. 2 is a schematic view showing an example of a uniaxial compressive strength tester that measures the uniaxial compressive strength of the cement-improved soil in step S01 of FIG.
図３は、本実施形態においてセメント改良土について行ったＸ線回折により得たＸ線回折チャートの例を示す図（ａ）、セメント改良土の圧縮強度と関連性を有する回折角（２θ）11.6〜11.7°における図３（ａ）の破線ａで囲む回折ピーク部分を拡大した図（ｂ）、同じく回折角（２θ）9.0〜9.1°における破線ｂで囲む回折ピーク部分を拡大した図（ｃ）、および回折ピークにおけるピークトップとバックグラウンドと回折ピーク強度との関係を示す模式図（ｄ）である。図４は、常圧環境(0.1MPa)と高圧環境(50MPa)の下で一軸圧縮強度を種々に変えた場合、回折角（２θ）11.6〜11.7°における回折ピーク強度と一軸圧縮強度との相関関係を示すグラフである。図５は、同じく、回折角（２θ）9.0〜9.1°における回折ピーク強度と一軸圧縮強度との相関関係を示すグラフである。 FIG. 3A is a diagram showing an example of an X-ray diffraction chart obtained by X-ray diffraction performed on cement-improved soil in this embodiment, and a diffraction angle (2θ) 11.6 having a relation with the compressive strength of cement-improved soil. FIG. 3B is an enlarged view of a diffraction peak portion surrounded by a broken line a in FIG. 3A at ˜11.7 °, and FIG. 5C is an enlarged view of a diffraction peak portion surrounded by a broken line b at a diffraction angle (2θ) of 9.0 to 9.1 °. FIG. 4D is a schematic diagram (d) showing a relationship among a peak top, a background, and a diffraction peak intensity in a diffraction peak. Figure 4 shows the correlation between diffraction peak intensity and uniaxial compressive strength at diffraction angles (2θ) of 11.6 to 11.7 ° when the uniaxial compressive strength is varied under normal pressure (0.1 MPa) and high pressure (50 MPa). It is a graph which shows a relationship. FIG. 5 is a graph showing the correlation between the diffraction peak intensity and the uniaxial compressive intensity at a diffraction angle (2θ) of 9.0 to 9.1 °.
本実施形態によるセメント改良土の強度推定方法では、セメント改良土の圧縮強度とＸ線回折による回折ピーク強度との相関関係を予め求めておくことが必要である。すなわち、図１のように、セメント改良土から採取した試料について一軸圧縮強度（本明細書では、単に「圧縮強度」という場合もある。）を測定する（Ｓ０１）。 In the method for estimating the strength of cement-improved soil according to the present embodiment, it is necessary to obtain in advance a correlation between the compressive strength of the cement-improved soil and the diffraction peak intensity by X-ray diffraction. That is, as shown in FIG. 1, the uniaxial compressive strength (in this specification, sometimes simply referred to as “compressive strength”) is measured for a sample collected from the cement-improved soil (S01).
一軸圧縮試験は、たとえば、JIS A1216：2009(土の一軸圧縮試験方法)規格に基づいて行われる。セメント改良土の施工現場で採取した改良体コアから成形等により一軸圧縮試験用の供試体Ｓを作製する。供試体Ｓは、たとえば、直径5cm、高さ10cmの円柱状である。図２のように、供試体Ｓを一軸圧縮試験機１０の上下の加圧板３，４間にセットし、圧縮装置２により加圧板４を押し上げることで、供試体Ｓに圧縮力を加え、圧縮力が大きくなるにつれて圧縮ひずみが増大する。この間の圧縮力および圧縮ひずみは、荷重計５，変位計６により測定され、記録され、応力ひずみ曲線を得る。この応力ひずみ曲線において圧縮ひずみが15％に達するまでの圧縮応力の最大値を一軸圧縮強度とする。
The uniaxial compression test is performed based on, for example, JIS A1216: 2009 (uniaxial compression test method for soil). A specimen S for a uniaxial compression test is produced by molding or the like from the improved core collected at the construction site of the cement improved soil. The specimen S is, for example, a cylindrical shape having a diameter of 5 cm and a height of 10 cm. As shown in FIG. 2, the specimen S is set between the upper and
また、ステップＳ０１と同じセメント改良土から採取した試料についてＸ線回折装置によりＸ線回折を行うことで回折ピーク強度およびその回折角（２θ）を測定する（Ｓ０２）。回折角（２θ）は、入射Ｘ線方向と回折Ｘ線方向とのなす角度である。なお、このＸ線回折は、ステップＳ０１で圧縮強度を測定した後の供試体から採取した試料により行ってもよい。 Further, the diffraction peak intensity and the diffraction angle (2θ) are measured by performing X-ray diffraction with an X-ray diffractometer on the sample collected from the same cement-modified soil as in step S01 (S02). The diffraction angle (2θ) is an angle formed by the incident X-ray direction and the diffraction X-ray direction. In addition, you may perform this X-ray diffraction with the sample extract | collected from the specimen after measuring compressive strength by step S01.
Ｘ線回折装置は、たとえば、株式会社リガク製Ｘ線回折装置（ＸＲＤ）：Rigaku SmartLab（登録商標／仕様：9kV回転対陰極(45kV,200mA)）を用いることができる。 As the X-ray diffractometer, for example, Rigaku Corporation X-ray diffractometer (XRD): Rigaku SmartLab (registered trademark / specifications: 9 kV rotating counter cathode (45 kV, 200 mA)) can be used.
図３（ａ）に測定したＸ線回折チャートの一例を示すが、横軸が回折角（２θ）（度）、縦軸が回折強度（Counts）で、複数の回折角（２θ）にそれぞれ回折ピークが出現している。図３（ａ）の複数の回折ピークのうち、破線ａで囲んだ回折ピークおよび破線ｂで囲んだ回折ピークが本発明者による検討の結果、セメント改良土の圧縮強度と関連性を有することが判明した。その回折角（２θ）は、図３（ａ）の破線ａ，ｂで囲む回折ピークを拡大した図３（ｂ）（ｃ）のように、11.6〜11.7°、9.0〜9.1°と特定される（Ｓ０３）。 FIG. 3A shows an example of the measured X-ray diffraction chart. The horizontal axis is the diffraction angle (2θ) (degrees), the vertical axis is the diffraction intensity (Counts), and diffraction is performed at a plurality of diffraction angles (2θ). A peak appears. Among the plurality of diffraction peaks in FIG. 3 (a), the diffraction peak surrounded by the broken line a and the diffraction peak surrounded by the broken line b are related to the compressive strength of the cement-improved soil as a result of examination by the inventors. found. The diffraction angle (2θ) is specified as 11.6 to 11.7 ° and 9.0 to 9.1 ° as shown in FIGS. 3B and 3C in which the diffraction peaks surrounded by broken lines a and b in FIG. (S03).
Ｘ線回折法において回折角（２θ）の位置および回折ピーク強度は測定対象の結晶構造に特有であり、かかる回折パターンから主に無機物質の同定が可能である。図３（ａ）の破線ｂで囲んだ回折ピークは、セメント系固化材のセメント水和物として析出するエトリンガイトによるものであるが、この回折角（２θ）は、9.0〜9.1°で、破線ａの回折ピークの回折角（２θ）11.6〜11.7°と相違する。また、回折角（２θ）11.6〜11.7°においてエトリンガイドの回折ピークが生じないことは公知であるため、回折角（２θ）11.6〜11.7°で特定される物質は、エトリンガイトではないと考えられる。 In the X-ray diffraction method, the position of the diffraction angle (2θ) and the diffraction peak intensity are specific to the crystal structure to be measured, and the inorganic substance can be mainly identified from the diffraction pattern. The diffraction peak surrounded by the broken line b in FIG. 3A is due to ettringite precipitated as cement hydrate of the cement-based solidified material, and the diffraction angle (2θ) is 9.0 to 9.1 °, and the broken line a The diffraction angle (2θ) of the diffraction peak is different from 11.6 to 11.7 °. Moreover, since it is known that the diffraction peak of the ettrin guide does not occur at the diffraction angle (2θ) of 11.6 to 11.7 °, the substance specified by the diffraction angle (2θ) of 11.6 to 11.7 ° is not considered to be ettringite. .
また、図３（ａ）〜（ｃ）の回折強度はバックグラウンドの影響を排除するために補正される。すなわち、図３（ｄ）のように、ピークトップからバックグラウンドを差し引いて求められる値を、本明細書では、補正された回折ピーク強度、または、単に回折ピーク強度という。 In addition, the diffraction intensities in FIGS. 3A to 3C are corrected in order to eliminate the influence of the background. That is, as shown in FIG. 3D, a value obtained by subtracting the background from the peak top is referred to as corrected diffraction peak intensity or simply diffraction peak intensity in this specification.
上記圧縮強度測定Ｓ０１と、回折角（２θ）11.6〜11.7°、9.0〜9.1°における回折ピーク強度測定Ｓ０２とを、セメント改良土の養生期間を変えたり、配合を変えたりすることで、圧縮強度の異なる複数のセメント改良土について繰り返し行う（Ｓ０４）。 The compression strength measurement S01 and the diffraction peak strength measurement S02 at diffraction angles (2θ) of 11.6 to 11.7 ° and 9.0 to 9.1 ° can be changed by changing the curing period of the cement-improved soil or changing the composition. It repeats about several cement improvement soils from which it differs (S04).
上記ステップＳ０１，Ｓ０２の結果から、図４のように、セメント改良土の圧縮強度と回折角（２θ）11.6〜11.7°における回折ピーク強度との相関関係を得る（Ｓ０５）。同様に、図５のように、セメント改良土の圧縮強度と回折角（２θ）9.0〜9.1°における回折ピーク強度との相関関係を得る。すなわち、図４，図５のように、回折ピーク強度が大きくなると、そのセメント改良土の一軸圧縮強度が大きくなるという相関関係を示し、たとえば、図４，図５に示すように、直線近似できる。 From the results of the above steps S01 and S02, as shown in FIG. 4, a correlation between the compressive strength of the cement-improved soil and the diffraction peak strength at diffraction angles (2θ) of 11.6 to 11.7 ° is obtained (S05). Similarly, as shown in FIG. 5, the correlation between the compressive strength of the cement-improved soil and the diffraction peak intensity at a diffraction angle (2θ) of 9.0 to 9.1 ° is obtained. That is, as shown in FIGS. 4 and 5, there is a correlation that, as the diffraction peak intensity increases, the uniaxial compressive strength of the cement-improved soil increases. For example, linear approximation can be performed as shown in FIGS. .
次に、推定対象のセメント改良土、すなわち、圧縮強度が不明であるセメント改良土について回折角（２θ）11.6〜11.7°における回折ピーク強度を上述と同様にして測定する（Ｓ０６）。 Next, the diffraction peak intensity at a diffraction angle (2θ) of 11.6 to 11.7 ° is measured in the same manner as described above for the cement improved soil to be estimated, that is, the cement improved soil whose compressive strength is unknown (S06).
次に、ステップＳ０５で得た図４のような圧縮強度と回折角（２θ）11.6〜11.7°における回折ピーク強度との相関関係に基づいて推定対象のセメント改良土について測定された回折ピーク強度からセメント改良土の圧縮強度を求める（Ｓ０７）。 Next, from the diffraction peak intensity measured for the cement-improved soil to be estimated based on the correlation between the compressive strength obtained in step S05 and the diffraction peak intensity at the diffraction angle (2θ) of 11.6 to 11.7 ° as shown in FIG. The compressive strength of the cement-improved soil is obtained (S07).
ステップＳ０７で求めた圧縮強度を推定対象のセメント改良土の圧縮強度と推定する（Ｓ０８）。 The compressive strength obtained in step S07 is estimated as the compressive strength of the cement-improved soil to be estimated (S08).
上述のように、本実施形態のセメント改良土の強度推定方法によれば、セメント改良土の圧縮強度と関連する回折ピーク強度およびその回折角（２θ）11.6〜11.7°、9.0〜9.1°を特定し、セメント改良土の圧縮強度とその特定した回折角（２θ）における回折ピーク強度との相関関係を得てから、推定対象のセメント改良土から採取した試料についてＸ線回折を行い、その特定した回折角（２θ）における回折ピーク強度を測定し、上記相関関係に基づいてその測定された回折ピーク強度からセメント改良土の圧縮強度を求め、その求めた圧縮強度を推定対象のセメント改良土の圧縮強度と推定することができる。このように、推定対象のセメント改良土から作製した供試体による一軸圧縮試験が不要であり、セメント改良土の圧縮強度の推定・確認を簡単な工程で行うことができる。従来のようなチェックボーリングにより改良体コアを採取する必要がないため作業工程が簡略化できる。また、一軸圧縮試験用の供試体を作製するためのコア成形等の手間と時間を要する前処理工程を省略できる。 As described above, according to the method for estimating the strength of cement-improved soil according to this embodiment, the diffraction peak intensity and the diffraction angle (2θ) 11.6 to 11.7 °, 9.0 to 9.1 ° associated with the compressive strength of the cement-improved soil are specified. Then, after obtaining the correlation between the compressive strength of the cement-improved soil and the diffraction peak intensity at the specified diffraction angle (2θ), the sample collected from the cement-improved soil to be estimated was subjected to X-ray diffraction and identified. The diffraction peak intensity at the diffraction angle (2θ) is measured, the compressive strength of the cement-improved soil is obtained from the measured diffraction peak intensity based on the above correlation, and the compression strength of the cement-improved soil to be estimated is compressed. It can be estimated as intensity. Thus, the uniaxial compression test by the test piece produced from the cement improvement soil to be estimated is unnecessary, and the compression strength of the cement improvement soil can be estimated and confirmed by a simple process. Since it is not necessary to collect improved cores by conventional check boring, the work process can be simplified. Moreover, the pre-processing process which requires time and effort, such as core shaping | molding for producing the specimen for a uniaxial compression test, can be skipped.
また、Ｘ線回折は、たとえば、2cm×2cmの試料ホルダーに試料を厚さ約0.5mmにつめたものをＸ線回折装置に装着して行うが、必要な試料は、0.2g（1g/cm3として）程度で、1g以下の微量の試料で済む。一軸圧縮試験用の供試体は、200g程度の試料が必要となるのに対し、かなり少ない試料で行うことができる。このため、量が少ない貴重な試料や、破損したボーリングコア試料でも圧縮強度推定が可能である。 X-ray diffraction is performed by, for example, mounting a sample holder of 2 cm x 2 cm with a thickness of about 0.5 mm on an X-ray diffractometer. The required sample is 0.2 g (1 g / cm (As 3 ), a small sample of 1g or less is sufficient. The specimen for the uniaxial compression test requires a sample of about 200 g, but can be performed with a considerably small number of samples. For this reason, it is possible to estimate the compressive strength of a valuable sample with a small amount or a damaged boring core sample.
また、ステップＳ０６の推定対象のセメント改良土についてのＸ線回折をポータブルタイプのＸ線回折装置により行うようにしてもよい。これにより、試料のＸ線回折を推定対象のセメント改良土の施工現場において行うことができるので、セメント改良土の圧縮強度の確認を迅速に行うことができ、その結果を施工現場における品質管理等に直ちに反映させることができる。このようなポータブルタイプのＸ線回折装置として、たとえば、オリンパス（株）から販売されているポータブルＸ線回折装置 TERRA（登録商標）を使用することができる。 Moreover, you may make it perform X-ray diffraction about the cement improvement soil of estimation object of step S06 with a portable type X-ray-diffraction apparatus. As a result, X-ray diffraction of the sample can be performed at the construction site of the cement-improved soil to be estimated, so the compressive strength of the cement-improved soil can be quickly confirmed, and the results are used for quality control at the construction site, etc. Can be reflected immediately. As such a portable type X-ray diffractometer, for example, a portable X-ray diffractometer TERRA (registered trademark) sold by Olympus Corporation can be used.
また、本実施形態のセメント改良土の強度推定方法では、推定対象のセメント改良土は、常圧環境下のみならず高圧環境下で施工されたものであってもよい。たとえば、深海の海底で施工されたセメント系固化材による改良地盤から採取した試料についてＸ線回折により、その圧縮強度を推定できる。このため、高圧環境から常圧環境に戻した際に試料破損が生じても圧縮強度推定が可能である。また、深海の海底の改良地盤から回収された試料のＸ線回折は、たとえば、母船においてポータブルタイプのＸ線回折装置により行うことができる。 Moreover, in the strength estimation method of the cement-improved soil according to the present embodiment, the estimation target cement-improved soil may be constructed not only under a normal pressure environment but also under a high pressure environment. For example, the compressive strength can be estimated by X-ray diffraction for a sample collected from an improved ground with cement-based solidified material constructed on the deep sea floor. For this reason, it is possible to estimate the compressive strength even if the sample is damaged when the high pressure environment is returned to the normal pressure environment. Further, X-ray diffraction of a sample collected from the improved ground on the deep sea bottom can be performed by a portable X-ray diffractometer in a mother ship, for example.
なお、上記ステップＳ０６，Ｓ０７では、推定対象のセメント改良土について回折角（２θ）11.6〜11.7°における回折ピーク強度を測定し、図４のような圧縮強度と回折角（２θ）11.6〜11.7°における回折ピーク強度との相関関係に基づいて圧縮強度を求めたが、回折角（２θ）9.0〜9.1°における回折ピーク強度を測定し、図５のような圧縮強度と回折角（２θ）9.0〜9.1°における回折ピーク強度との相関関係に基づいて圧縮強度を求めるようにしてもよい。あるいは、回折角（２θ）11.6〜11.7°および9.0〜9.1°における回折ピーク強度をそれぞれ測定し、図４，図５のような相関関係に基づいてセメント改良土の圧縮強度をそれぞれ求め、求めた２つの圧縮強度を比較し、たとえば、その低い値の方を圧縮強度と推定したり、または、その相加平均値を圧縮強度と推定してもよい。 In steps S06 and S07, the diffraction peak intensity at the diffraction angle (2θ) of 11.6 to 11.7 ° is measured for the cement-improved soil to be estimated, and the compression strength and diffraction angle (2θ) of 11.6 to 11.7 ° as shown in FIG. The compressive strength was determined based on the correlation with the diffraction peak intensity in FIG. 5, but the diffraction peak intensity at a diffraction angle (2θ) of 9.0 to 9.1 ° was measured, and the compressive strength and diffraction angle (2θ) of 9.0 to 9.0 as shown in FIG. The compressive strength may be obtained based on the correlation with the diffraction peak intensity at 9.1 °. Alternatively, the diffraction peak intensities at diffraction angles (2θ) of 11.6 to 11.7 ° and 9.0 to 9.1 ° were measured, respectively, and the compressive strength of the cement-improved soil was determined based on the correlation as shown in FIGS. Two compressive strengths may be compared, for example, the lower value may be estimated as the compressive strength, or the arithmetic average value thereof may be estimated as the compressive strength.
また、図４と図５を比較すると、回折角（２θ）11.6〜11.7°の図４の方がデータのばらつきが少ないので、精度のよい圧縮強度の推定が可能であるが、回折角（２θ）11.6〜11.7°における回折ピークがどのような物質に由来するのか現時点では不明であるため、必要に応じて回折角（２θ）9.0〜9.1°の図５の相関関係を用いることが好ましいと考えられる。 Further, when FIG. 4 is compared with FIG. 5, since the data variation is smaller in FIG. 4 where the diffraction angle (2θ) is 11.6 to 11.7 °, it is possible to estimate the compressive strength more accurately, but the diffraction angle (2θ ) Since it is unclear at this time what kind of substance the diffraction peak at 11.6 to 11.7 ° is derived from, it is preferable to use the correlation of FIG. 5 with a diffraction angle (2θ) of 9.0 to 9.1 ° as necessary. It is done.
次に、セメント改良土の一軸圧縮強度試験およびＸ線回折測定の実験例について説明する。本実験例で用いたセメント改良土の配合条件・養生条件を次の表１に示す。 Next, experimental examples of uniaxial compressive strength test and X-ray diffraction measurement of cement-improved soil will be described. Table 1 shows the blending conditions and curing conditions of the cement-improved soil used in this experimental example.
本実験例における一軸圧縮試験のステップＳ１１〜Ｓ１７を図６に示す。図６のように、配合材料（ベントナイト、セメント、水）を表１のように配合し（Ｓ１１）、これらを混合・攪拌し（Ｓ１２）、モールドに注入した（Ｓ１３）。モールドから取り出した試験体を常圧（0.1MPa）で水中養生し（Ｓ１４）、別のモールドから取り出した試験体を高圧にした圧力容器内で水中養生した（Ｓ１５）。高圧条件（拘束条件）は、10,30,50MPaの三条件で、水深1000,3000,5000mの水底における圧力状態を模擬した。成形により一軸圧縮試験用の供試体を作製し（Ｓ１６）、表１の養生期間（3,7,9,28日）経過後に図２のような一軸圧縮試験機により一軸圧縮試験を行った（Ｓ１７）。 FIG. 6 shows steps S11 to S17 of the uniaxial compression test in this experimental example. As shown in FIG. 6, compounding materials (bentonite, cement, water) were blended as shown in Table 1 (S11), mixed and stirred (S12), and injected into the mold (S13). The test body taken out from the mold was cured in water at normal pressure (0.1 MPa) (S14), and the test body taken out from another mold was cured in water in a pressure vessel having a high pressure (S15). The high pressure conditions (constraint conditions) were three conditions of 10, 30, and 50 MPa, and simulated the pressure state at the bottom of the water at 1000, 3000, and 5000 m depth. A specimen for a uniaxial compression test was prepared by molding (S16), and a uniaxial compression test was performed using a uniaxial compression tester as shown in FIG. 2 after the curing period (3, 7, 9, 28 days) in Table 1 had passed ( S17).
図７に、常圧（0.1MPa）および高圧（50MPa）の拘束条件で養生期間を3日、7日、9日（常圧のみ）、28日とした場合の一軸圧縮試験の結果を、養生期間3日の圧縮強度σ3、7日の圧縮強度σ7、9日の圧縮強度σ9、28日の圧縮強度σ28として示す。図８は、0.1,10,30,50MPaの拘束圧と一軸圧縮強度との関係を養生期間ごとに示すグラフである。図７，図８からセメント改良土の養生期間が長くなると圧縮強度が増加すること、および、拘束圧が大きくなると圧縮強度が増加することがわかる。
Figure 7 shows the results of the uniaxial compression test when the curing period is 3 days, 7 days, 9 days (normal pressure only), and 28 days under normal pressure (0.1 MPa) and high pressure (50 MPa) restraint conditions. It is shown as compressive strength sigma 28 periods compressive strength of 3 days sigma 3, a compressive strength of 7
次に、常圧（0.1MPa）および高圧（50MPa）の拘束条件で養生期間が3日、7日、28日の一軸圧縮試験に用いた供試体から採取した試料についてＸ線回折を行った。Ｘ線回折は図１のステップＳ０２と同様にして行い、計測時間は20分に統一し、最大回折角（２θ）を60.0°とした。 Next, X-ray diffraction was performed on a sample collected from a specimen used in a uniaxial compression test under a restraint condition of normal pressure (0.1 MPa) and high pressure (50 MPa) with a curing period of 3, 7, and 28 days. X-ray diffraction was performed in the same manner as in step S02 of FIG. 1, the measurement time was unified to 20 minutes, and the maximum diffraction angle (2θ) was set to 60.0 °.
図９、図１０に、常圧（0.1MPa）、高圧（50MPa）で、養生期間が3日（ａ）、7日（ｂ）、28日（ｃ）の場合のＸ線回折チャートを示す。図９（ａ）〜（ｃ），図１０（ａ）〜（ｃ）の各Ｘ線回折チャートの回折ピークのうち長円で囲んだ回折ピークの回折角（２θ）が11.6〜11.7°である。このような実験例から、回折角（２θ）11.6〜11.7°における回折ピーク強度とセメント改良土の圧縮強度との関連性を本発明者が見いだした。 FIG. 9 and FIG. 10 show X-ray diffraction charts for normal pressure (0.1 MPa), high pressure (50 MPa), and curing periods of 3 days (a), 7 days (b), and 28 days (c). Of the diffraction peaks of the X-ray diffraction charts of FIGS. 9A to 9C and FIGS. 10A to 10C, the diffraction angle (2θ) of the diffraction peak surrounded by an ellipse is 11.6 to 11.7 °. . From such experimental examples, the present inventor found a relationship between the diffraction peak intensity at a diffraction angle (2θ) of 11.6 to 11.7 ° and the compressive strength of the cement-improved soil.
図１１，図１２にも、常圧（0.1MPa）、高圧（50MPa）で、養生期間が3日（ａ）、7日（ｂ）、28日（ｃ）の場合のＸ線回折チャートを示すが、図１１（ａ）〜（ｃ），図１２（ａ）〜（ｃ）の各Ｘ線回折チャートの回折ピークのうち長円で囲んだ回折ピークの回折角（２θ）が9.0〜9.1°である。このような実験例から、回折角（２θ）9.0〜9.1°における回折ピーク強度とセメント改良土の圧縮強度との関連性を本発明者が見いだした。 FIGS. 11 and 12 also show X-ray diffraction charts for normal pressure (0.1 MPa), high pressure (50 MPa), and curing periods of 3 days (a), 7 days (b), and 28 days (c). However, the diffraction angle (2θ) of the diffraction peak surrounded by an ellipse among the diffraction peaks of the X-ray diffraction charts of FIGS. 11 (a) to 11 (c) and FIGS. 12 (a) to 12 (c) is 9.0 to 9.1 °. It is. From such experimental examples, the present inventor found the relationship between the diffraction peak intensity at a diffraction angle (2θ) of 9.0 to 9.1 ° and the compressive strength of the cement-improved soil.
図９〜図１２のＸ線回折チャートの回折強度は、図３（ｄ）のように、バックグラウンドの影響を排除するために補正され、その補正された回折ピーク強度と測定された圧縮強度との相関関係を得ることができる。図４，図５は、その相関関係を示すグラフで、図４，図５には実験例の常圧（0.1MPa）で養生期間9日の一軸圧縮強度σ9のデータも示されている。
The diffraction intensities of the X-ray diffraction charts of FIGS. 9 to 12 are corrected to eliminate the influence of the background, as shown in FIG. 3D, and the corrected diffraction peak intensity and the measured compressive intensity Can be obtained. FIG. 4 and FIG. 5 are graphs showing the correlation, and FIG. 4 and FIG. 5 also show data of the uniaxial compressive strength σ 9 at the normal pressure (0.1 MPa) of the experimental example and the
以上のように本発明を実施するための形態について説明したが、本発明はこれらに限定されるものではなく、本発明の技術的思想の範囲内で各種の変形が可能である。たとえば、本明細書におけるセメント改良土は、改良対象土にセメントを混合し、その圧縮強度を向上させたものであるが、セメントを母材として各種の有効成分を添加したセメント系固化材による改良土も含まれることはもちろんである。 As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the cement-improved soil in this specification is obtained by mixing cement with the soil to be improved and improving its compressive strength, but improved by a cement-based solidifying material to which various active ingredients are added using cement as a base material. Of course, soil is included.
また、セメント改良土は、たとえば、ベントナイト・水・セメントの組み合わせによるものも含み、かかる組み合わせによる材料は、土木・建築工事で発生する隙間の充填材、地盤強度の増強材、地中に設置した芯材の固定などに使用される。 Cement-modified soil includes, for example, bentonite / water / cement combinations, and materials based on such combinations are installed in gaps generated in civil engineering and construction work, ground strength enhancing materials, and installed in the ground. Used for fixing core material.
また、図１のフローチャートにおいて、ステップＳ０１〜Ｓ０５は、セメント改良土のＸ線回折法による強度推定の準備段階で、図４，図５のような回折ピーク強度と圧縮強度との相関関係を得る。かかる相関関係に基づいて推定対象のセメント改良土の圧縮強度をステップＳ０６〜Ｓ０８で推定するので、ステップＳ０６〜Ｓ０８がセメント改良土の施工現場等で好ましくは行われる。ただし、ステップＳ０１〜Ｓ０５を必要に応じて追加的に行うことで、回折ピーク強度と圧縮強度との精度のよい相関関係を得ることができる。 Further, in the flowchart of FIG. 1, steps S01 to S05 are steps for preparing the strength estimation by the X-ray diffraction method of cement-improved soil, and obtain the correlation between the diffraction peak intensity and the compressive strength as shown in FIGS. . Since the compressive strength of the cement-improved soil to be estimated is estimated in steps S06 to S08 based on such correlation, steps S06 to S08 are preferably performed at the construction site of the cement-improved soil. However, an accurate correlation between the diffraction peak intensity and the compression intensity can be obtained by additionally performing steps S01 to S05 as necessary.
また、本明細書で、高圧とは、0.1MPaを超えた圧力を意味し、たとえば、高圧ガス保安法では、0.2MPa以上が高圧とされている。 In the present specification, high pressure means a pressure exceeding 0.1 MPa. For example, in the high-pressure gas safety method, a high pressure is 0.2 MPa or more.
本発明のセメント改良土の強度推定方法によれば、セメント改良土の圧縮強度の確認を簡単な工程で微量な試料で行うことができ、セメント改良の施工現場で迅速に行うことが可能で、たとえば、強度推定結果を品質管理に直ちに反映させることができる。 According to the method for estimating the strength of cement-improved soil according to the present invention, the compressive strength of cement-improved soil can be confirmed with a small amount of sample in a simple process, and can be quickly performed at the site of cement improvement. For example, the strength estimation result can be immediately reflected in quality control.
また、セメント・セメント系固化材によるセメント改良土は、軟弱地盤の改良、有機質土壌の安定化、川や池の底にたまるヘドロの固化処理、下水汚泥の固化等に用いられるが、これらに限定されるものではない。地盤改良の具体例としては、構造物の基礎地盤改良、仮設地盤としての改良、法面の浸食防止のための改良、路床・路盤の改良等の浅層改良、または、構造物基礎の改良、盛土の安定性確保、土留めの強化と掘削地盤のヒービング・ボイリング防止、護岸の強化等の深層改良があり、これらに適宜用いられる。 In addition, cement-modified soil using cement / cement-based solidifying material is used for soft ground improvement, stabilization of organic soil, solidification of sludge accumulated in the bottom of rivers and ponds, solidification of sewage sludge, etc. Is not to be done. Specific examples of ground improvement include improvement of the foundation ground of the structure, improvement as a temporary ground, improvement for preventing erosion of slopes, improvement of shallow layers such as improvement of roadbed and roadbed, or improvement of structure foundation There are deep layer improvements such as ensuring stability of embankment, strengthening earth retaining, preventing heaving / boiling of excavated ground, strengthening revetment, etc., which are used as appropriate.
１０ 一軸圧縮試験機
Ｓ 供試体
σ3 圧縮強度（養生期間3日）
σ7 圧縮強度（養生期間7日）
σ28 圧縮強度（養生期間28日）
10 Uniaxial compression tester S Specimen σ 3 Compressive strength (curing
σ 7 compressive strength (curing period 7 days)
σ 28 compressive strength (curing
Claims (7)
推定対象のセメント改良土から採取した試料についてＸ線回折を行うことで、回折ピーク強度およびその回折角（２θ）を測定するステップと、
予め得たセメント改良土の圧縮強度と前記回折角（２θ）における回折ピーク強度との相関関係に基づいて前記測定された回折ピーク強度からセメント改良土の圧縮強度を求めるステップと、を有し、
前記求めた圧縮強度を前記推定対象のセメント改良土の圧縮強度と推定するセメント改良土の強度推定方法。 A method for estimating the compressive strength of cement-modified soil by an X-ray diffraction method,
Measuring the diffraction peak intensity and its diffraction angle (2θ) by performing X-ray diffraction on a sample collected from the cement improvement soil to be estimated;
Obtaining the compressive strength of the cement-improved soil from the measured diffraction peak intensity based on the correlation between the compressive strength of the cement-improved soil obtained in advance and the diffraction peak intensity at the diffraction angle (2θ),
A method for estimating the strength of cement-improved soil, wherein the determined compressive strength is estimated as the compressive strength of the target cement-improved soil.
セメント改良土から採取した試料について圧縮強度を測定する第１ステップと、
前記セメント改良土から採取した試料についてＸ線回折を行うことで回折ピーク強度およびその回折角（２θ）を測定する第２ステップと、
前記測定された圧縮強度および回折ピーク強度に基づいて前記圧縮強度と関連性を有する回折ピーク強度およびその回折角（２θ）を特定する第３ステップと、
前記セメント改良土の圧縮強度と前記特定した回折角（２θ）における回折ピーク強度との相関関係を得る第４ステップと、
推定対象のセメント改良土から採取した試料についてＸ線回折を行うことで前記特定した回折角（２θ）における回折ピーク強度を測定する第５ステップと、
前記圧縮強度と前記特定した回折角（２θ）における回折ピーク強度との相関関係に基づいて前記測定された回折ピーク強度からセメント改良土の圧縮強度を求める第６ステップと、を有し、
前記求めた圧縮強度を前記推定対象のセメント改良土の強度と推定するセメント改良土の強度推定方法。 A method for estimating the compressive strength of cement-modified soil by an X-ray diffraction method,
A first step of measuring the compressive strength of a sample collected from cement-modified soil;
A second step of measuring the diffraction peak intensity and its diffraction angle (2θ) by performing X-ray diffraction on a sample collected from the cement-modified soil;
A third step of identifying a diffraction peak intensity and a diffraction angle (2θ) that are related to the compression intensity based on the measured compression intensity and diffraction peak intensity;
A fourth step of obtaining a correlation between the compressive strength of the cement-modified soil and the diffraction peak intensity at the specified diffraction angle (2θ);
A fifth step of measuring the diffraction peak intensity at the specified diffraction angle (2θ) by performing X-ray diffraction on a sample collected from the cement improved soil to be estimated;
A sixth step of determining the compressive strength of the cement-improved soil from the measured diffraction peak strength based on the correlation between the compressive strength and the diffraction peak strength at the specified diffraction angle (2θ),
A method for estimating the strength of cement-improved soil, wherein the determined compressive strength is estimated as the strength of the cement-improved soil to be estimated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017155672A JP6886363B2 (en) | 2017-08-10 | 2017-08-10 | Strength estimation method for cement-improved soil |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017155672A JP6886363B2 (en) | 2017-08-10 | 2017-08-10 | Strength estimation method for cement-improved soil |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2019035208A true JP2019035208A (en) | 2019-03-07 |
| JP6886363B2 JP6886363B2 (en) | 2021-06-16 |
Family
ID=65637134
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2017155672A Active JP6886363B2 (en) | 2017-08-10 | 2017-08-10 | Strength estimation method for cement-improved soil |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6886363B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2021056021A (en) * | 2019-09-27 | 2021-04-08 | 太平洋セメント株式会社 | Quality evaluation method for improved ground |
| CN114018694A (en) * | 2021-11-30 | 2022-02-08 | 中国路桥工程有限责任公司 | Unconfined compressive strength's sample surface state survey device |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58205575A (en) * | 1982-05-22 | 1983-11-30 | Shimizu Constr Co Ltd | Solidifying method of incineration ash of paper making sludge and desulfurization ash |
| JP2005146275A (en) * | 2003-10-24 | 2005-06-09 | Growth Factor:Kk | Agent for improving, solidifying, and stabilizing soil and its quality |
| JP2011252850A (en) * | 2010-06-03 | 2011-12-15 | Nippon Steel Corp | Quantitative analysis method of ettringite in inorganic oxide-based material |
| JP2015097995A (en) * | 2013-11-19 | 2015-05-28 | 株式会社エコ・プロジェクト | ION EXCHANGER INCLUDING PROCESSED SLUDGE PRODUCT CONTAINING ALUMINIUM COMPONENT (Al COMPONENT), MANUFACTURING METHOD OF ION EXCHANGER, AND HARMFUL ELEMENT ION REMOVING AGENT CONTAINING ION EXCHANGER |
| JP2016074559A (en) * | 2014-10-07 | 2016-05-12 | 株式会社大林組 | Cement slurry and ground improvement method |
-
2017
- 2017-08-10 JP JP2017155672A patent/JP6886363B2/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58205575A (en) * | 1982-05-22 | 1983-11-30 | Shimizu Constr Co Ltd | Solidifying method of incineration ash of paper making sludge and desulfurization ash |
| JP2005146275A (en) * | 2003-10-24 | 2005-06-09 | Growth Factor:Kk | Agent for improving, solidifying, and stabilizing soil and its quality |
| JP2011252850A (en) * | 2010-06-03 | 2011-12-15 | Nippon Steel Corp | Quantitative analysis method of ettringite in inorganic oxide-based material |
| JP2015097995A (en) * | 2013-11-19 | 2015-05-28 | 株式会社エコ・プロジェクト | ION EXCHANGER INCLUDING PROCESSED SLUDGE PRODUCT CONTAINING ALUMINIUM COMPONENT (Al COMPONENT), MANUFACTURING METHOD OF ION EXCHANGER, AND HARMFUL ELEMENT ION REMOVING AGENT CONTAINING ION EXCHANGER |
| JP2016074559A (en) * | 2014-10-07 | 2016-05-12 | 株式会社大林組 | Cement slurry and ground improvement method |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2021056021A (en) * | 2019-09-27 | 2021-04-08 | 太平洋セメント株式会社 | Quality evaluation method for improved ground |
| JP7401238B2 (en) | 2019-09-27 | 2023-12-19 | 太平洋セメント株式会社 | Quality evaluation method of improved ground |
| CN114018694A (en) * | 2021-11-30 | 2022-02-08 | 中国路桥工程有限责任公司 | Unconfined compressive strength's sample surface state survey device |
| CN114018694B (en) * | 2021-11-30 | 2023-11-24 | 中国路桥工程有限责任公司 | Sample surface state measuring device without confined compressive strength |
Also Published As
| Publication number | Publication date |
|---|---|
| JP6886363B2 (en) | 2021-06-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Tan et al. | Properties of Singapore marine clays improved by cement mixing | |
| Yi et al. | Compressive behaviour of fibre-reinforced cemented paste backfill | |
| Horpibulsk et al. | Strength development in cement admixed Bangkok clay: laboratory and field investigations | |
| Lu et al. | Accelerated testing of cement treated Singapore marine clay cured under elevated temperature | |
| Nahali et al. | Effect of Na3PO4 addition in mortar on steel reinforcement corrosion behavior in 3% NaCl solution | |
| Kasama et al. | Undrained shear strength of cement-treated soils | |
| JP2012031618A (en) | Method for estimating strength of modified dredged material and method for modifying dredged material | |
| Gamil et al. | Simulation and development of instrumental setup to be used for cement grouting of sand soil | |
| JP2019035208A (en) | Strength estimation method of cement improved soil | |
| Reiter et al. | Slow penetration for characterizing concrete for digital fabrication | |
| Pérez et al. | Durability of self-healing ultra-high-strength reinforced micro-concrete under freeze–thaw or chloride attack | |
| Kasama et al. | High-strengthening of cement-treated clay by mechanical dehydration | |
| Shepherd et al. | Experimental study into the mechanical properties of plastic concrete: compressive strength development over time, tensile strength and elastic modulus | |
| Van Impe et al. | Deep mixing in underwater conditions: a laboratory and field investigation | |
| Behravan et al. | Changes in the rate of ion penetration of alternative cementitious materials with time | |
| JP6832497B2 (en) | Estimating method of strength characteristics of soil cement, estimation device, quality control method of rooting part during pile construction, quality control device | |
| Liu et al. | Observation of microstructure formation process of cement paste using non-destructive methods | |
| JP3886980B2 (en) | Improved soil formulation design method | |
| CN112513376B (en) | Method and apparatus for setting W/C in deep mixing processing method | |
| Liu et al. | In situ characterisation of the depth and mass of water intrusion in unsaturated cement pastes via X-ray computed tomography | |
| JP2007032114A (en) | Blending design method and device of cement and fine grain content of ground improvement construction method | |
| Yao et al. | Maximum shear Modulus of cement-treated Singapore marine clay | |
| Andrews-Phaedonos | Test methods for the assessment of durability of concrete | |
| Chan | Strength recovery of remolded dredged marine clay: thixotropic hardening vs. induced cementation | |
| JP2020200689A (en) | Improved soil manufacturing method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20200508 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20210315 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20210323 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20210330 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20210511 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20210514 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6886363 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |