JP7549971B2 - Method for estimating bentonite mixing ratio - Google Patents
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Description
本発明は、ベントナイト混合土のベントナイト混合率の推定方法に関する。 The present invention relates to a method for estimating the bentonite mixing ratio of bentonite-mixed soil.
ベントナイトは膨潤性が高く遮水性が高いので、これを砂や土と混合したベントナイト混合土が産業廃棄物処分場や放射性廃棄物の処分施設などにおいて人工バリア材料として用いられる。 Bentonite has high swelling and water impermeability, so it is mixed with sand and soil to form bentonite mixtures, which are used as an engineered barrier material in industrial waste disposal sites and radioactive waste disposal facilities.
人工バリア材料として用いられる場合、ベントナイト混合土に求められる透水性や膨潤性などの物性を規定し、管理することが理想であるが、この物性は直接測定することができないか、あるいはその測定が困難であるので、ベントナイト混合率、密度および水分量等を測定、管理することで上記物性を担保させることとしている。 When used as an engineered barrier material, it would be ideal to specify and control the physical properties required for bentonite-mixed soil, such as permeability and swelling, but since these properties cannot be measured directly, or are difficult to measure, the above properties are guaranteed by measuring and controlling the bentonite mixing ratio, density, moisture content, etc.
非特許文献１は、ベントナイト混合率の測定方法として、ｉ）メチレンブルー（ＭＢ）吸着量測定、ｉｉ）電気伝導度測定、ｉｉｉ）細粒分含有率測定、ｉｖ）粘度測定、ｖ）沈降試験、ｖｉ）近赤外線分光測定等が検討されたことを開示する。
Non-Patent
非特許文献１のベントナイト混合率の測定方法によれば、ｉ）メチレンブルー（ＭＢ）吸着量測定、ｉｉｉ）細粒分含有率測定およびｖ）沈降試験が比較的測定精度が高い方法であるが、測定に手間を要するという問題がある（ｉ）ＭＢ吸着量測定については、測定に熟練度も要求される）。ｖｉ）近赤外線分光測定は簡単に測定を実施することができるが、精度のバラツキが大きい。さらに、ｉｖ）粘度測定（ファンネル粘度測定）はよく使われる方法であるが、ファンネル粘度が大きくなる領域ではベントナイト混合率との相関が失われ、測定精度が低下する。
According to the method for measuring the bentonite mixing ratio in
上記課題を鑑みた本願発明の目的は、測定に手間も熟練度も要することなく、精度の高いベントナイト混合率の推定方法を提供することにある。 In view of the above problems, the objective of the present invention is to provide a method for estimating the bentonite mixing ratio with high accuracy without requiring much effort or skill for measurement.
発明者らは、鋭意検討の結果、ベントナイト混合土の、ベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式に高い相関関係があることを見出し、本発明を完成させた。 After extensive research, the inventors discovered that there is a high correlation between the water content of bentonite-mixed soil, corrected for the bentonite mixing ratio, and the water potential, and thus completed the present invention.
すなわち、本発明の前記目的は、ベントナイト混合土のベントナイト混合率の推定方法であって、
ベントナイト混合率未知のベントナイト混合土の含水比と水分ポテンシャルとを測定する測定工程と、前記測定した含水比および水分ポテンシャルの値を、予め求めた、ベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式に当てはめて前記ベントナイト混合率未知のベントナイト混合土のベントナイト混合率を推定する推定工程と、を有し、前記相関式が、ベントナイト混合率が既知であって、且つ前記ベントナイト混合率が異なる複数の既知ベントナイト混合土について含水比が異なる複数の試料を作成したうえで該複数の試料について含水比と水分ポテンシャルの測定を行い、前記複数の試料について前記測定で得られた水分ポテンシャルの値と、同じく前記測定で得られた前記複数の試料の含水比の値を前記既知のベントナイト混合率で除して得られた前記補正含水比の値と、の関係に基づいて作成されたものであることを特徴とするベントナイト混合率の推定方法によって達成される。
That is, the object of the present invention is to provide a method for estimating a bentonite mixing ratio of a bentonite-mixed soil, comprising:
The present invention is achieved by a method for estimating a bentonite mixing ratio, the method comprising: a measuring step of measuring a water content and a water potential of a bentonite-mixed soil with an unknown bentonite mixing ratio; and an estimating step of estimating a bentonite mixing ratio of the bentonite-mixed soil with an unknown bentonite mixing ratio by applying the measured water content and water potential values to a correlation equation between a corrected water content corrected by the bentonite mixing ratio and water potential obtained in advance, the correlation equation being created based on a relationship between the water content and water potential values of the samples obtained by measuring the water content and water potential of the samples, the water content and water potential being obtained by dividing the water content values of the samples obtained by measuring the water content by the known bentonite mixing ratio.
また、本発明のベントナイト混合率の推定方法は、前記相関式を、１ＭＰａ以上１００ＭＰａ以下の水分ポテンシャルの値の範囲で用いることが好ましい。 In addition, the method for estimating the bentonite mixing ratio of the present invention preferably uses the correlation equation in a range of water potential values from 1 MPa to 100 MPa.
さらに、好ましくは、前記ベントナイト混合土の用途が、放射性廃棄物の処分施設の人工バリア材料用途である。 More preferably, the bentonite mixed soil is used as an engineered barrier material in a radioactive waste disposal facility.
本発明のベントナイト混合率の推定方法によれば、予めベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式を求めておき、この相関式にベントナイト混合土の含水比と水分ポテンシャルとを測定して当てはめることでベントナイト混合率が未知のベントナイト混合土のベントナイト混合率を求めることが可能となる。補正含水比と水分ポテンシャルとの間には高い相関があり、且つ、ベントナイト混合土の含水比と水分ポテンシャルは測定に熟練度及び手間を要求しないので、測定に手間も熟練度も要することなく、精度の高いベントナイト混合率の推定方法がもたらされる。 According to the method for estimating the bentonite mixing ratio of the present invention, a correlation equation between the corrected moisture content corrected by the bentonite mixing ratio and the moisture potential is determined in advance, and the moisture content and moisture potential of the bentonite-mixed soil are measured and applied to this correlation equation, making it possible to determine the bentonite mixing ratio of the bentonite-mixed soil whose bentonite mixing ratio is unknown. Since there is a high correlation between the corrected moisture content and the moisture potential, and since the moisture content and moisture potential of the bentonite-mixed soil do not require skill or effort to measure, a highly accurate method for estimating the bentonite mixing ratio is provided without requiring effort or skill to measure.
＜ベントナイト混合率の推定方法＞
本発明のベントナイト混合土のベントナイト混合率の推定方法は、ベントナイト混合率未知のベントナイト混合土の含水比と水分ポテンシャルとを測定する測定工程と、測定した含水比および水分ポテンシャルの値を、予め求めた、ベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式に当てはめてベントナイト混合率未知のベントナイト混合土のベントナイト混合率を推定する推定工程と、を有する。
<Method for estimating bentonite mixing ratio>
The method for estimating the bentonite mixing ratio of a bentonite-mixed soil of the present invention includes a measuring step of measuring the moisture content and water potential of a bentonite-mixed soil having an unknown bentonite mixing ratio, and an estimation step of estimating the bentonite mixing ratio of the bentonite-mixed soil having an unknown bentonite mixing ratio by applying the measured moisture content and water potential values to a correlation equation between a corrected moisture content corrected by the bentonite mixing ratio and the water potential obtained in advance.
［１．測定工程］
本工程では、上記のとおり、ベントナイト混合率未知のベントナイト混合土の含水比と水分ポテンシャルとを測定する。
[1. Measurement process]
In this step, as described above, the water content and water potential of the bentonite-mixed soil with an unknown bentonite mixing ratio are measured.
ベントナイト混合土とは、ベントナイトと土との混合物をいう。ベントナイトは、モンモリロナイトを主成分として、石英、クリストバライトなどのケイ酸鉱物を副成分として含む粘性土であり、たとえば、クニミネ工業社、日本ベントナイト工業社、ホージュン社などから市販されているベントナイト製品を用いることができる。 Bentonite mixed soil is a mixture of bentonite and soil. Bentonite is a clayey soil containing montmorillonite as the main component and silicate minerals such as quartz and cristobalite as secondary components. For example, bentonite products commercially available from Kunimine Kogyo Co., Ltd., Nippon Bentonite Kogyo Co., Ltd., Hojun Co., Ltd., etc. can be used.
ベントナイトと混合される土としては、粒径３．９μｍ以上２ｍｍ以下の範囲の土を用いることができ、好ましくは粒径５０μｍ以上２ｍｍ以下の範囲の土を用いることができる。粒径３．９μｍ以上とすることでベントナイト混合土から粘土が排除され、後述する相関式の確度を高めることができる。 The soil to be mixed with bentonite can have a particle size ranging from 3.9 μm to 2 mm, and preferably a particle size ranging from 50 μm to 2 mm. By making the particle size 3.9 μm or more, clay is eliminated from the bentonite-mixed soil, which increases the accuracy of the correlation equation described below.
ベントナイトと混合される土は、例えば、コンクリート骨材用の山砂、珪砂、川砂等が挙げられる。 Examples of soil that can be mixed with bentonite include mountain sand, silica sand, and river sand, which are used as concrete aggregates.
ベントナイト混合率はベントナイト混合土に占めるベントナイトの質量割合であり、ベントナイト混合率の測定において、混合されるベントナイトおよび土は絶乾後のものを用いるものとする。 The bentonite mixing ratio is the mass ratio of bentonite in the bentonite-mixed soil, and when measuring the bentonite mixing ratio, the bentonite and soil to be mixed shall be completely dried.
含水比は、混合土に含まれる水の質量を混合土の乾燥質量で除して、混合土に含まれる水分の割合を示したものであり、ＪＩＳ Ａ１２０３：２００９に従って測定される。 The moisture content is calculated by dividing the mass of water in the soil mixture by the dry mass of the soil mixture, and indicates the percentage of moisture contained in the soil mixture, and is measured in accordance with JIS A1203:2009.
土壌の水分ポテンシャルとは、土壌に含まれる水の化学ポテンシャルを指し、水の表面張力や土粒子の吸着力によるマトリックポテンシャル成分、溶質を含むことによる浸透ポテンシャル成分、そして重力ポテンシャル成分から構成されている。水分ポテンシャルは、冷却鏡法による水分ポテンシャル測定器であるＷＰ４Ｃ（アイネクス社販売）などにより簡便に測定することができる（以上、測定工程）。 Soil water potential refers to the chemical potential of the water contained in the soil, and is composed of a matric potential component due to the surface tension of water and the adsorptive power of soil particles, an osmotic potential component due to the inclusion of solutes, and a gravitational potential component. Water potential can be easily measured using a water potential measuring device that uses the cooled mirror method, such as the WP4C (sold by INEX Co., Ltd.) (above, measurement process).
［２．推定工程］
本工程では、［１．測定工程］で測定した含水比および水分ポテンシャルの値を、予め求めた、ベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式に当てはめてベントナイト混合率未知のベントナイト混合土のベントナイト混合率を推定する。
[2. Estimation process]
In this step, the values of the water content and water potential measured in [1. Measurement step] are applied to a correlation equation between the corrected water content corrected by the bentonite mixing ratio and the water potential, which was obtained in advance, to estimate the bentonite mixing ratio of the bentonite-mixed soil with an unknown bentonite mixing ratio.
（２－１）ベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式の作成
ベントナイトは水を容易に取り込むが、混合される土はベントナイトと比較して水を取り込む力が弱く、したがって、含水比を一定にした場合に、ベントナイト混合土の水分ポテンシャルはベントナイトの混合率に依存することから、ベントナイト混合土のベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式が高い相関を有するものと考えられる。
(2-1) Creation of a correlation equation between corrected moisture content corrected by bentonite mixing ratio and water potential Bentonite easily absorbs water, but the soil with which it is mixed has a weaker ability to absorb water than bentonite. Therefore, when the moisture content is kept constant, the water potential of bentonite-mixed soil depends on the bentonite mixing ratio, and it is therefore believed that the correlation equation between the corrected moisture content corrected by the bentonite mixing ratio of bentonite-mixed soil and water potential has a high correlation.
ベントナイト混合土のベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式は、ベントナイト混合率が既知であって、且つ前記ベントナイト混合率が異なる複数の既知ベントナイト混合土について含水比が異なる複数の試料を作成したうえで該複数の試料について含水比と水分ポテンシャルの測定を行い、前記複数の試料について前記測定で得られた水分ポテンシャルの値と、同じく前記測定で得られた前記複数の試料の含水比の値を前記既知のベントナイト混合率で除して得られた前記補正含水比の値と、の関係に基づいて作成されたものである。 The correlation equation between the corrected moisture content corrected by the bentonite mixing ratio of bentonite-mixed soil and the water potential was created by preparing a number of samples with different moisture contents for a number of known bentonite-mixed soils with known bentonite mixing ratios, measuring the moisture content and water potential for the samples, and based on the relationship between the values of the water potential obtained by the measurements for the samples and the corrected moisture content values obtained by dividing the moisture content values of the samples obtained by the measurements by the known bentonite mixing ratio.
ベントナイト混合率が既知であって、且つ前記ベントナイト混合率が異なる複数の既知ベントナイト混合土としては、ベントナイトの混合率違いで２以上のベントナイトの混合率が既知の既知ベントナイト混合土を、好ましくはベントナイトの混合率違いで３以上のベントナイトの混合率が既知の既知ベントナイト混合土を用意する。 As the multiple known bentonite mixed soils with known bentonite mixing ratios and different bentonite mixing ratios, two or more known bentonite mixed soils with different bentonite mixing ratios and known bentonite mixing ratios, preferably three or more known bentonite mixed soils with different bentonite mixing ratios and known bentonite mixing ratios, are prepared.
これらベントナイト混合率が異なる２以上の既知ベントナイト混合土から、含水比を変更した試料を複数準備する。含水比を変更した試料は２以上であり、好ましくは３以上、より好ましくは４以上準備する。 Prepare multiple samples with different water content from two or more known bentonite-mixed soils with different bentonite mixing ratios. Prepare two or more samples with different water content, preferably three or more, and more preferably four or more.
なお、相関式の作成に用いる既知ベントナイト混合土のベントナイトおよび土は、混合比を除き、上記ベントナイト混合率未知のベントナイト混合土のベントナイトおよび土と同じであることが、ベントナイト混合率の推定精度を高める観点から好ましい。 In addition, from the viewpoint of improving the estimation accuracy of the bentonite mixing ratio, it is preferable that the bentonite and soil of the known bentonite-mixed soil used to create the correlation equation are the same as the bentonite and soil of the bentonite-mixed soil with an unknown bentonite mixing ratio, except for the mixing ratio.
次に、含水比を変更した各試料について、含水比と水分ポテンシャルを測定する。この測定は、上記［１．測定工程］で述べた測定方法に従ってなされる。 Next, the moisture content and water potential of each sample with different moisture content are measured. This measurement is performed according to the measurement method described above in [1. Measurement process].
後述する実施例では、ベントナイトＡについて、ベントナイト混合率２５％、５０％、７５％、１００％の４つのベントナイト混合土について、含水比０～５０％の間で各ベントナイト混合土について各９個の試料を調整し、含水比と水分ポテンシャルを測定しており、測定結果は図１（ａ）に示される。 In the examples described below, nine samples of bentonite A were prepared for four bentonite mixed soils with bentonite mixing ratios of 25%, 50%, 75%, and 100% and moisture content between 0% and 50%. The moisture content and water potential were measured, and the measurement results are shown in Figure 1(a).
次に、測定された含水比の値を既知のベントナイト混合率で除して、以下の式（１）で示す補正含水比の値を得る。 Next, the measured moisture content is divided by the known bentonite mixing ratio to obtain the corrected moisture content value shown in the following formula (1).
各試料について、補正含水比Ｗｃ（％）を横軸とし、水分ポテンシャルＰを縦軸としたグラフは図２（ａ）に示されるが、ここでは、図２（ａ）のプロットを図１（ａ）に重ねた図を図４に示す。 Figure 2(a) shows a graph for each sample with the corrected water content Wc (%) on the horizontal axis and the water potential P on the vertical axis, but here, Figure 4 shows the plot of Figure 2(a) superimposed on Figure 1(a).
図４に示すように、各試料の含水比と水分ポテンシャルのプロットが、ベントナイト混合率で補正された補正含水比と水分ポテンシャルのプロットとすることで右方向に移動し、一つの曲線上に並ぶ相関関係を示すことから、この補正含水比と水分ポテンシャルとの関係から相関式を作成することができる。 As shown in Figure 4, the plot of moisture content and water potential for each sample shifts to the right when the corrected moisture content corrected for the bentonite mixing ratio is plotted against the water potential, showing a correlation that lines up on a single curve. A correlation equation can therefore be created from the relationship between the corrected moisture content and water potential.
相関式は、例えば、補正含水比と水分ポテンシャルのデータから最小二乗法により作成した回帰直線や回帰曲線を示す相関式として得ることができる。 The correlation equation can be obtained, for example, as a correlation equation showing a regression line or regression curve created by the least squares method from the corrected water content and water potential data.
なお、図２（ａ）では横軸を補正含水比Ｗｃ（％）とし、縦軸を水分ポテンシャルＰとしているが、縦軸と横軸を入れ替えてもよい。 In FIG. 2(a), the horizontal axis represents the corrected water content Wc (%) and the vertical axis represents the water potential P, but the vertical and horizontal axes may be interchanged.
後述する実施例では、ベントナイト混合土Ａについて相関式（Ａ）が、ベントナイト混合土Ｂについて相関式（Ｂ）が、それぞれ得られている。 In the examples described below, correlation equation (A) was obtained for bentonite mixed soil A, and correlation equation (B) was obtained for bentonite mixed soil B.
また、補正含水比と水分ポテンシャルの相関の高さの観点から、相関式は、水分ポテンシャルＰが０．２ＭＰａ以上３００ＭＰａ以下の範囲で、好ましくは１ＭＰａ以上１００ＭＰａ以下の範囲で用いることが好ましい。 In addition, from the viewpoint of the high correlation between the corrected water content and the water potential, it is preferable to use the correlation equation when the water potential P is in the range of 0.2 MPa or more and 300 MPa or less, and preferably in the range of 1 MPa or more and 100 MPa or less.
（２－２）ベントナイト混合率未知のベントナイト混合土のベントナイト混合率の推定
次に、上記（２－１）の項目で得られた相関式に［１．測定工程］で測定した含水比および水分ポテンシャルの値を当てはめることで、ベントナイト混合率Ｃｍを算出（推定）する。
(2-2) Estimation of bentonite mixing ratio of bentonite-mixed soil with unknown bentonite mixing ratio Next, the bentonite mixing ratio Cm is calculated (estimated) by applying the water content and water potential measured in [1. Measurement process] to the correlation equation obtained in the above item (2-1).
具体的には、例えば、相関式（Ａ）に水分ポテンシャルの値を当てはめることで補正含水比Ｗｃの値が算出され、この補正含水比の値と含水比の値とを以下の式（１）
補正含水比Ｗｃ（％）＝含水比Ｗ（％）／ベントナイト混合率Ｃｍ （１）
に代入することで、ベントナイト混合率Ｃｍが算出（推定）されることとなる（以上、推定工程）。
Specifically, for example, the value of the corrected water content Wc is calculated by applying the value of the water potential to the correlation equation (A), and the value of the corrected water content Wc and the value of the water content are calculated using the following equation (1):
Corrected water content ratio Wc (%) = water content ratio W (%)/bentonite mixing ratio Cm (1)
By substituting the above, the bentonite mixing ratio Cm is calculated (estimated) (the above is the estimation process).
本発明のベントナイト混合率の推定方法は、放射性廃棄物の処分施設の人工バリア材料用途で使用されるベントナイト混合土のベントナイト混合率の推定に、埋設処分された廃棄物の覆土としてのベントナイト混合土のベントナイト混合率の推定に、およびその他止水材として用いられるベントナイト混合土のベントナイト混合率の推定に使用することができる。 The method for estimating the bentonite mixing ratio of the present invention can be used to estimate the bentonite mixing ratio of bentonite-mixed soil used as an engineered barrier material in radioactive waste disposal facilities, to estimate the bentonite mixing ratio of bentonite-mixed soil used as a cover soil for buried waste disposal, and to estimate the bentonite mixing ratio of bentonite-mixed soil used as a water-stopping material.
以下、実施例を示して本発明について具体的に説明するが、本発明はこれらの実施例のみに限定されるものではない。 The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
＜１．相関式の作成＞
（１）ベントナイト混合土の調整
ベントナイトＡ（クニゲルＶ１、クニミネ工業社製）と珪砂（三河珪砂６号、三河珪石株式会社製）とを、それぞれ以下の表１の質量比で混合し、ベントナイトＡ混合土を得た。
<1. Creating a correlation equation>
(1) Preparation of Bentonite Mixed Soil Bentonite A (Kunigel V1, Kunimine Kogyo Co., Ltd.) and silica sand (Mikawa Silica Sand No. 6, Mikawa Silica Co., Ltd.) were mixed in the mass ratios shown in Table 1 below to obtain a bentonite A mixed soil.
同様に、ベントナイトＢ（クニボンドＲＷ、クニミネ工業社製）と珪砂（三河珪砂６号、三河珪石株式会社製）とを、それぞれ以下の表１の質量比で混合し、ベントナイトＢ混合土を得た。 Similarly, bentonite B (Kunibond RW, manufactured by Kunimine Kogyo Co., Ltd.) and silica sand (Mikawa Silica Sand No. 6, manufactured by Mikawa Silica Co., Ltd.) were mixed in the mass ratios shown in Table 1 below to obtain bentonite B mixed soil.
（２）調整した各ベントナイト混合土の水分ポテンシャルＰおよび含水比Ｗの測定
表１の各ベントナイト混合土について、水の含有割合を変えてそれぞれ９個の試験体を作成した。この各試験体の含水比Ｗおよび水分ポテンシャルＰを測定し、得られた測定値について、含水比Ｗを横軸、水分ポテンシャルＰを縦軸としてプロットし、各ベントナイト混合土について含水比Ｗと水分ポテンシャルＰとの関係を示すグラフを作成した。このグラフを図１に示す。
(2) Measurement of water potential P and water content W of each adjusted bentonite mixed soil For each bentonite mixed soil in Table 1, nine test specimens were prepared by varying the water content. The water content W and water potential P of each test specimen were measured, and the measured values were plotted with the water content W on the horizontal axis and the water potential P on the vertical axis to create a graph showing the relationship between the water content W and the water potential P for each bentonite mixed soil. This graph is shown in Figure 1.
図１に示すように、ベントナイト混合土は、ベントナイト混合率Ｃｍに応じて、含水比Ｗと水分ポテンシャルＰとの間に一定の関係を示すように見えた。 As shown in Figure 1, bentonite-mixed soil appears to show a certain relationship between water content W and water potential P depending on the bentonite mixing ratio Cm.
なお、含水比Ｗの測定は赤外線水分計（FD-720、ケツト科学研究所製）により行い、水分ポテンシャルＰの測定は冷却鏡法による水分ポテンシャル測定装置（ＷＰ４Ｃ、アイネクス社製）により行った。 The water content W was measured using an infrared moisture meter (FD-720, Kett Electric Laboratory), and the water potential P was measured using a water potential measuring device (WP4C, Inex Co., Ltd.) using the cooled mirror method.
（３）補正含水比Ｗｃと水分ポテンシャルＰとの相関式の作成
次に、各試験体の含水比Ｗの測定された値をその試験体のベントナイト混合率Ｃｍで除した補正含水比Ｗｃの値を求め、全ての試験体について、この補正含水比Ｗｃの値を横軸と、対応する水分ポテンシャルＰの値を縦軸としてプロットし、全てのベントナイト混合土について補正含水比Ｗｃと水分ポテンシャルＰとの関係を示すグラフを作成した。このグラフを図２に示す。
(3) Creation of a correlation equation between corrected moisture content Wc and water potential P Next, the measured value of the moisture content W of each test specimen was divided by the bentonite mixing ratio Cm of that specimen to determine the value of corrected moisture content Wc, and for all test specimens, the value of corrected moisture content Wc was plotted on the horizontal axis and the corresponding value of water potential P on the vertical axis to create a graph showing the relationship between corrected moisture content Wc and water potential P for all bentonite-mixed soils. This graph is shown in Figure 2.
図２に示すように、補正含水比Ｗｃと水分ポテンシャルＰとの間に高い相関関係があることが示された。 As shown in Figure 2, it was shown that there is a high correlation between the corrected water content Wc and the water potential P.
次に、図２のグラフから横軸と縦軸を入れ替えたグラフを作成し、図３に示すとともに、相関式を作成し、同時に決定係数（Ｒ二乗値）を求めた。それぞれ、相関式及び決定係数（Ｒ二乗値）を以下に示す。 Next, a graph was created by swapping the horizontal and vertical axes of the graph in Figure 2, as shown in Figure 3. A correlation equation was also created, and the coefficient of determination (R-squared value) was calculated. The correlation equation and coefficient of determination (R-squared value) are shown below.
ベントナイト混合土Ａの相関式（Ａ）
Ｗｃ（Ｗ／Ｃｍ）＝４０．４３２Ｐ－０．３３７ （Ａ）
（Ｒ２=０．９８２２）
ベントナイト混合土Ｂの相関式（Ｂ）
Ｗｃ（Ｗ／Ｃｍ）＝６１．０８Ｐ－０．２７２ （Ｂ）
（Ｒ２=０．９７１）
したがって、ベントナイト混合土Ａおよびベントナイト混合土Ｂについて作成した相関式が高い相関を有することが示された。
Correlation equation for bentonite mixed soil A (A)
Wc (W/Cm) = 40.432P -0.337 (A)
(R 2 =0.9822)
Correlation equation for bentonite mixed soil B (B)
Wc (W/Cm) = 61.08P -0.272 (B)
( R2 =0.971)
Therefore, it was shown that the correlation equations created for bentonite mixed soil A and bentonite mixed soil B have a high correlation.
＜２．相関式を用いたベントナイト混合率の推定＞
次に、上記＜１．相関式の作成＞で作成した相関式を用いて推定したベントナイト混合土のベントナイト混合率Ｃｍが実際のベントナイト混合土のベントナイト混合率Ｃｍと整合するかどうか、以下に検討した。
2. Estimation of bentonite mixing ratio using correlation equation
Next, it was examined whether the bentonite mixing ratio Cm of the bentonite-mixed soil estimated using the correlation equation created in the above <1. Creation of the correlation equation> was consistent with the actual bentonite mixing ratio Cm of the bentonite-mixed soil.
ベントナイトＡ（クニゲルＶ１、クニミネ工業社製）と珪砂（三河珪砂６号、三河珪石株式会社製）とを、ベントナイトＡ：珪砂＝７０：３０の質量比で混合した７０％ベントナイトＡ混合土を調整した。 Bentonite A (Kunigel V1, Kunimine Kogyo Co., Ltd.) and silica sand (Mikawa Silica Sand No. 6, Mikawa Silica Co., Ltd.) were mixed in a mass ratio of bentonite A:silica sand = 70:30 to prepare a 70% bentonite A mixed soil.
同様に、ベントナイトＢ（クニボンドＲＷ、クニミネ工業社製）と珪砂（三河珪砂６号、三河珪石株式会社製）とを、ベントナイトＢ：珪砂＝７０：３０の質量比で混合した７０％ベントナイトＢ混合土を調整した。 Similarly, bentonite B (Kunibond RW, Kunimine Kogyo Co., Ltd.) and silica sand (Mikawa Silica Sand No. 6, Mikawa Silica Co., Ltd.) were mixed in a mass ratio of bentonite B:silica sand = 70:30 to prepare a 70% bentonite B mixed soil.
７０％ベントナイトＡ混合土および７０％ベントナイトＢ混合土について、赤外線水分計（FD-720、ケツト科学研究所製）により含水比Ｗを測定し、水分ポテンシャル測定装置（ＷＰ４Ｃ、アイネクス社製）により水分ポテンシャルＰの測定を行った。測定結果を以下の表２に示す。 For the 70% bentonite A mixed soil and the 70% bentonite B mixed soil, the moisture content W was measured using an infrared moisture meter (FD-720, Kett Electric Laboratory) and the moisture potential P was measured using a moisture potential measuring device (WP4C, Inex Co., Ltd.). The measurement results are shown in Table 2 below.
７０％ベントナイトＡ混合土の含水比Ｗ及び水分ポテンシャルＰの値を相関式（Ａ）、７０％ベントナイトＢ混合土の含水比Ｗ及び水分ポテンシャルＰの値を相関式（Ｂ）にそれぞれ代入した結果、混合率はそれぞれ、６９．４％（７０％ベントナイトＡ混合土）、７０．９％（７０％ベントナイトＢ混合土）と算出された。 By substituting the values of the water content W and water potential P of the 70% bentonite A mixed soil into correlation equation (A), and the values of the water content W and water potential P of the 70% bentonite B mixed soil into correlation equation (B), the mixture ratios were calculated to be 69.4% (70% bentonite A mixed soil) and 70.9% (70% bentonite B mixed soil), respectively.
これらの算出値は７０％ベントナイトＡ混合土及び７０％ベントナイトＢ混合土のベントナイトの混合率Ｃｍと非常に近い値であり、したがって、ベントナイト混合率未知のベントナイト混合土のベントナイト混合率Ｃｍを、含水比Ｗと水分ポテンシャルＰを測定し、上記相関式に当てはめることで精度高く推定できることが示された。 These calculated values are very close to the bentonite mixing ratio Cm of 70% bentonite A mixed soil and 70% bentonite B mixed soil, and therefore it was shown that the bentonite mixing ratio Cm of bentonite mixed soil with unknown bentonite mixing ratio can be estimated with high accuracy by measuring the water content W and water potential P and applying them to the above correlation equation.
Claims (3)
ベントナイト混合率未知のベントナイト混合土の含水比と水分ポテンシャルとを測定する測定工程と、
前記測定した含水比および水分ポテンシャルの値を、予め求めた、ベントナイト混合率で補正した補正含水比と水分ポテンシャルとの相関式および式（１）
補正含水比Ｗｃ（％）＝含水比Ｗ（％）／ベントナイト混合率Ｃｍ （１）
に当てはめて前記ベントナイト混合率未知のベントナイト混合土のベントナイト混合率を推定する推定工程と、
を有し、
前記相関式が、
ベントナイト混合率が既知であって、且つ前記ベントナイト混合率が異なる複数の既知ベントナイト混合土について含水比が異なる複数の試料を作成したうえで該複数の試料について含水比と水分ポテンシャルの測定を行い、
前記複数の試料について前記測定で得られた水分ポテンシャルの値と、同じく前記測定で得られた前記複数の試料の含水比の値を前記既知のベントナイト混合率で除して得られた前記補正含水比の値と、の関係に基づいて作成されたものであり、
前記ベントナイト混合率未知のベントナイト混合土に混合された土の粒径および前記ベントナイト混合率が既知であって、且つ前記ベントナイト混合率が異なる複数の既知ベントナイト混合土に混合された土の粒径が、共に３．９μｍ以上２ｍｍ以下の範囲にあることを特徴とするベントナイト混合率の推定方法。 A method for estimating a bentonite mixing ratio of bentonite-mixed soil, comprising the steps of:
A measuring step of measuring the water content and water potential of the bentonite-mixed soil having an unknown bentonite mixing ratio;
The measured values of water content and water potential are corrected by the bentonite mixing ratio, and a correlation equation between the corrected water content and water potential is calculated using the formula (1)
Corrected water content ratio Wc (%) = water content ratio W (%)/bentonite mixing ratio Cm (1)
an estimation step of estimating the bentonite mixing ratio of the bentonite-mixed soil having an unknown bentonite mixing ratio by applying the above formula to the bentonite-mixed soil;
having
The correlation equation is
A plurality of samples having different water contents are prepared for a plurality of known bentonite mixed soils having a known bentonite mixing ratio, and the water contents and water potentials of the plurality of samples are measured;
the relationship between the water potential values obtained by the measurement of the plurality of samples and the corrected water content values obtained by dividing the water content values of the plurality of samples obtained by the measurement by the known bentonite mixing ratio;
The method for estimating a bentonite mixing ratio is characterized in that the particle size of the soil mixed into the bentonite mixed soil having an unknown bentonite mixing ratio and the particle size of the soil mixed into a plurality of known bentonite mixed soils having known bentonite mixing ratios and different bentonite mixing ratios are both in the range of 3.9 μm or more and 2 mm or less.
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| JP2001004619A (en) | 1999-06-21 | 2001-01-12 | Taisei Corp | Estimation method of bentonite mixing ratio |
| US20140123738A1 (en) | 2011-07-05 | 2014-05-08 | Institut De Recherche Pour Le Developpement (Ird) | Device for measurement coupled with water parameters of soil |
| JP2018128372A (en) | 2017-02-09 | 2018-08-16 | 株式会社安藤・間 | Bentonite mixed soil measuring method and bentonite mixed soil measuring device |
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| JP2001004619A (en) | 1999-06-21 | 2001-01-12 | Taisei Corp | Estimation method of bentonite mixing ratio |
| US20140123738A1 (en) | 2011-07-05 | 2014-05-08 | Institut De Recherche Pour Le Developpement (Ird) | Device for measurement coupled with water parameters of soil |
| JP2018128372A (en) | 2017-02-09 | 2018-08-16 | 株式会社安藤・間 | Bentonite mixed soil measuring method and bentonite mixed soil measuring device |
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