JP7610787B2 - Soil improvement method, potassium sulfate-containing soil improvement material, and improved soil - Google Patents
Soil improvement method, potassium sulfate-containing soil improvement material, and improved soil Download PDFInfo
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- JP7610787B2 JP7610787B2 JP2020074215A JP2020074215A JP7610787B2 JP 7610787 B2 JP7610787 B2 JP 7610787B2 JP 2020074215 A JP2020074215 A JP 2020074215A JP 2020074215 A JP2020074215 A JP 2020074215A JP 7610787 B2 JP7610787 B2 JP 7610787B2
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- 239000002689 soil Substances 0.000 title claims description 191
- 239000000463 material Substances 0.000 title claims description 136
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 title claims description 73
- 229910052939 potassium sulfate Inorganic materials 0.000 title claims description 73
- 235000011151 potassium sulphates Nutrition 0.000 title claims description 73
- 238000000034 method Methods 0.000 title claims description 37
- 239000011398 Portland cement Substances 0.000 claims description 50
- 239000004927 clay Substances 0.000 claims description 14
- 229910052602 gypsum Inorganic materials 0.000 claims description 11
- 239000010440 gypsum Substances 0.000 claims description 11
- 238000004181 pedogenesis Methods 0.000 claims description 7
- 238000010586 diagram Methods 0.000 description 24
- 239000002956 ash Substances 0.000 description 10
- 238000012360 testing method Methods 0.000 description 9
- 239000002893 slag Substances 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000002245 particle Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 229910001583 allophane Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000012669 compression test Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 230000036571 hydration Effects 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
- 239000008239 natural water Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Landscapes
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
Description
本発明は、地盤改良方法、硫酸カリウム含有地盤改良材、及び、改良土に関する。 The present invention relates to a ground improvement method, a potassium sulfate-containing ground improvement material, and improved soil.
地盤が軟弱で種々の用途に適さない場合、斯かる地盤を構成する土と、普通ポルトランドセメントを主成分とする地盤改良材とを混合して改良土を形成し、該改良土を固化させることで地盤を改良する方法が知られている。斯かる方法によって、地盤の強度、安定性、耐久性等を向上させることができる（特許文献１参照）。 When the ground is soft and unsuitable for various uses, a method is known in which the soil that constitutes the ground is mixed with a ground improvement material whose main component is ordinary Portland cement to form improved soil, and the improved soil is then solidified to improve the ground. This method can improve the strength, stability, durability, etc. of the ground (see Patent Document 1).
ところで、上記のような地盤改良材であっても、土の性質によっては、十分な強度を発現する改良土を形成することができない場合がある。このような土の一例としては、火山灰質粘性土が挙げられる。該火山灰質粘性土は、地盤改良材と混合しても、一般的な粘性土に比べて、改良土の強度が高くなり難いことが知られている。その理由としては、以下のものが考えられる。
即ち、火山灰質粘性土には特有の粘土鉱物であるアロフェンが多く含まれる。また、アロフェンは、カルシウムイオンを吸着する性質がある。そのため、火山灰質粘性土と地盤改良材とを混合すると、地盤改良材に含まれるカルシウムイオンがアロフェンに吸着され、普通ポルトランドセメントの水和が阻害されると考えられる。その結果、改良土の強度が発現し難くなると考えられる。
However, even with the above-mentioned ground improvement materials, depending on the properties of the soil, it may not be possible to form improved soil with sufficient strength. One example of such soil is volcanic ash clay soil. It is known that even when mixed with a ground improvement material, it is difficult to increase the strength of the improved soil compared to general clay soil. The reasons for this are thought to be as follows.
That is, volcanic ash clay soil contains a lot of allophane, a unique clay mineral. Allophane also has the property of adsorbing calcium ions. Therefore, when volcanic ash clay soil is mixed with ground improvement material, the calcium ions contained in the ground improvement material are adsorbed by allophane, which is thought to inhibit the hydration of ordinary Portland cement. As a result, it is thought that the improved soil will have difficulty in developing its strength.
上記のように、改良土の強度が発現し難い土を対象に、十分な強度を発現させる方法として、地盤改良材の量を増やすことが考えられる。しかし、地盤改良材の量を増やすと、それに伴って発生する排泥（改良土）の処分にコストが掛かると共に、排泥による環境への負荷が増大することが懸念される。
そこで、他の方法として、早強ポルトランドセメントを主成分とする地盤改良材を用いる方法が提案されている。早強ポルトランドセメントは、水和反応速度が比較的早く、カルシウムが多く含まれるＣ３Ｓを比較的多く含むため、このような地盤改良材を用いることで、十分な強度を発現する改良土を形成することが可能となる。
As mentioned above, increasing the amount of ground improvement material is one way to improve soil that is difficult to improve in strength. However, increasing the amount of ground improvement material increases the cost of disposing of the resulting sludge (improved soil), and there is concern that the sludge will place a greater burden on the environment.
As an alternative method, a method has been proposed in which a ground improvement material containing high-early-strength Portland cement as a main component is used. High-early-strength Portland cement has a relatively fast hydration reaction rate and contains a relatively large amount of C3S , which contains a lot of calcium. By using such a ground improvement material, it is possible to form improved soil that exhibits sufficient strength.
しかしながら、早強ポルトランドセメントは、普通ポルトランドセメントと比べて調達が困難な場合がある。さらに、早強ポルトランドセメントは普通ポルトランドセメントに比べて水硬率が高いため、焼成エネルギーが高くなり、それに伴い二酸化炭素の排出量も増加する。このため、普通ポルトランドセメントを主成分とする地盤改良材を用いて、早強ポルトランドセメントを主成分とする地盤改良材と同等の強度を発現させる技術が望まれている。 However, high-early-strength Portland cement can be more difficult to procure than ordinary Portland cement. Furthermore, because high-early-strength Portland cement has a higher hydraulic hardness than ordinary Portland cement, it requires more energy to burn and therefore emits more carbon dioxide. For this reason, there is a demand for technology that uses ground improvement materials whose main component is ordinary Portland cement to achieve the same strength as ground improvement materials whose main component is high-early-strength Portland cement.
そこで、本発明は、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成された改良土と同等の強度を発現する改良土を形成することができる地盤改良方法、及び、硫酸カリウム含有地盤改良材を提供することを課題とする。
また、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成された改良土と同等の強度を発現する改良土を提供することを課題とする。
Therefore, an object of the present invention is to provide a ground improvement method capable of forming improved soil exhibiting strength equivalent to that of improved soil formed using a ground improvement material containing high-early-strength Portland cement as a main component, and a potassium sulfate-containing ground improvement material.
Another object of the present invention is to provide improved soil that exhibits strength equivalent to that of improved soil formed using a ground improvement material whose main component is high-early-strength Portland cement.
本発明に係る地盤改良方法は、対象土と地盤改良材とを混合して改良土を形成する地盤改良方法であって、対象土と地盤改良材と硫酸カリウムとを混合して改良土を形成する改良土形成工程を備えており、地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、改良土形成工程では、対象土の単位体積に対して混合する地盤改良材の質量（ｘ）と、対象土の単位体積に対して混合する硫酸カリウムの質量（ｙ）との関係が下記（１）式を満たすように、対象土と地盤改良材と硫酸カリウムとを混合する。
ｙ≧０．１２６５ｘ－１１．７２７・・・（１）
The ground improvement method of the present invention is a ground improvement method for forming improved soil by mixing a target soil with a ground improvement material, and includes an improved soil formation step of forming improved soil by mixing the target soil, the ground improvement material, and potassium sulfate, the ground improvement material containing ordinary Portland cement as a main component, and in the improved soil formation step, the target soil, the ground improvement material, and potassium sulfate are mixed so that the relationship between the mass (x) of the ground improvement material to be mixed per unit volume of the target soil and the mass (y) of potassium sulfate to be mixed per unit volume of the target soil satisfies the following formula (1).
y≧0.1265x-11.727...(1)
斯かる構成によれば、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成した改良土と同等の強度を発現する改良土を形成することができる。 This configuration makes it possible to form improved soil that exhibits the same strength as improved soil formed using a ground improvement material whose main component is high-early-strength Portland cement.
対象土の単位体積に対して混合する地盤改良材の質量（ｘ）に対する対象土の単位体積に対して混合する硫酸カリウムの質量（ｙ）の割合が６．６質量％以上であることが好ましい。 It is preferable that the ratio of the mass (y) of potassium sulfate to be mixed per unit volume of the target soil to the mass (x) of the ground improvement material to be mixed per unit volume of the target soil is 6.6% by mass or more.
斯かる構成によれば、より良好な強度を発現する改良土を形成することができる。 This configuration allows for the formation of improved soil with better strength.
本発明に係る硫酸カリウム含有地盤改良材は、対象土と混合されて改良土を形成する地盤改良材と、硫酸カリウムとを含んでおり、地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、地盤改良材と硫酸カリウムとの合計質量に対する硫酸カリウムの質量割合（ｚ）は、下記（２）式を満たす。
ｚ≧ｙ／（ｘ＋ｙ）×１００・・・（２）
（ｘ：対象土の単位体積に対して混合する地盤改良材の質量）
（ｙ＝０．１２６５ｘ－１１．７２７）
The potassium sulfate-containing ground improvement material of the present invention contains a ground improvement material that is mixed with a target soil to form improved soil, and potassium sulfate, the ground improvement material containing ordinary Portland cement as a main component, and the mass ratio (z) of potassium sulfate to the total mass of the ground improvement material and potassium sulfate satisfies the following formula (2).
z≧y/(x+y)×100...(2)
(x: mass of ground improvement material to be mixed per unit volume of target soil)
(y=0.1265x-11.727)
斯かる構成によれば、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成した改良土と同等の強度を発現する改良土を形成することができる。 This configuration makes it possible to form improved soil that exhibits the same strength as improved soil formed using a ground improvement material whose main component is high-early-strength Portland cement.
本発明に係る改良土は、対象土と地盤改良材と硫酸カリウムとを含む改良土であって、地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、対象土の単位体積に対して混合される地盤改良材の質量（ｘ）と、対象土の単位体積に対して混合される硫酸カリウムの質量（ｙ）との関係が下記（１）式を満たす。
ｙ≧０．１２６５ｘ－１１．７２７・・・（１）
The improved soil of the present invention is an improved soil containing a target soil, a ground improvement material, and potassium sulfate, wherein the ground improvement material contains ordinary Portland cement as a main component, and the relationship between the mass (x) of the ground improvement material mixed per unit volume of the target soil and the mass (y) of potassium sulfate mixed per unit volume of the target soil satisfies the following formula (1).
y≧0.1265x-11.727...(1)
斯かる構成によれば、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成した改良土と同等の強度を発現させることができる。 This configuration allows the soil to achieve the same strength as improved soil made using a ground improvement material whose main component is high-early-strength Portland cement.
本発明によれば、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成された改良土と同等の強度を発現する改良土を形成することができる地盤改良方法、及び、硫酸カリウム含有地盤改良材を提供することができる。また、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成された改良土と同等の強度を発現する改良土を提供することができる。 According to the present invention, it is possible to provide a ground improvement method capable of forming improved soil that exhibits the same strength as improved soil formed using a ground improvement material whose main component is high-early-strength Portland cement, and a potassium sulfate-containing ground improvement material. It is also possible to provide improved soil that exhibits the same strength as improved soil formed using a ground improvement material whose main component is high-early-strength Portland cement.
＜第一実施形態＞
以下、本発明の第一実施形態について、説明する。
First Embodiment
A first embodiment of the present invention will be described below.
本実施形態に係る地盤改良方法は、対象土と地盤改良材とを混合して改良土を形成するものである。 The ground improvement method according to this embodiment involves mixing the target soil with a ground improvement material to form improved soil.
地盤改良材は、普通ポルトランドセメントを主成分として含む。該普通ポルトランドセメントとは、「ＪＩＳ Ｒ ５２１０：２００９ ポルトランドセメント」に規定される普通ポルトランドセメントをいう。地盤改良材の質量に対する普通ポルトランドセメントの質量の割合としては、特に限定されるものではなく、例えば、２０～９６質量％であることが好ましく、４０～７２質量％であることがより好ましい。 The ground improvement material contains ordinary Portland cement as a main component. The ordinary Portland cement is the ordinary Portland cement defined in "JIS R 5210:2009 Portland cement". The ratio of the mass of ordinary Portland cement to the mass of the ground improvement material is not particularly limited, but is preferably 20 to 96 mass%, and more preferably 40 to 72 mass%, for example.
地盤改良材が含みうる普通ポルトランドセメント以外の成分としては、特に限定されるものではなく、例えば、高炉スラグ、フライアッシュ、シリカ質混合材（ポゾラン）等が挙げられる。 Components other than ordinary Portland cement that may be contained in the ground improvement material are not particularly limited, but examples include blast furnace slag, fly ash, and siliceous admixtures (pozzolana).
地盤改良材が高炉スラグを含む場合、該高炉スラグとしては、例えば、高炉水砕スラグの微粉末等が挙げられる。該高炉水砕スラグの微粉末としては、ＪＩＳ Ａ ６２０６：２０１３の“高炉スラグ微粉末”を用いることができる。
高炉水砕スラグの微粉末の比表面積としては、特に限定されるものではなく、例えば、２，７５０ｃｍ２／ｇ以上１０，０００ｃｍ２／ｇ未満であることが好ましい。なお、比表面積は、ＪＩＳ Ｒ ５２０１：２０１５の比表面積試験に従って測定することができる。
地盤改良材の質量に対する高炉スラグの質量の割合としては、特に限定されるものではなく、例えば、０質量％以上６０質量％以下であることが好ましく、２０質量％以上４５質量％以下であることがより好ましい。
When the ground improvement material contains blast furnace slag, the blast furnace slag may be, for example, finely divided powder of granulated blast furnace slag. As the finely divided powder of granulated blast furnace slag, the "ground powder of blast furnace slag" of JIS A 6206:2013 may be used.
The specific surface area of the fine powder of granulated blast furnace slag is not particularly limited, and is preferably, for example, 2,750 cm 2 /g or more and less than 10,000 cm 2 /g. The specific surface area can be measured according to the specific surface area test of JIS R 5201:2015.
The ratio of the mass of blast furnace slag to the mass of the ground improvement material is not particularly limited, and is, for example, preferably 0 mass% or more and 60 mass% or less, and more preferably 20 mass% or more and 45 mass% or less.
また、地盤改良材は、普通ポルトランドセメント以外の成分として石膏を含んでもよい。該石膏は、普通ポルトランドセメントを構成するものとは別のものを意味し、無水石膏（ＣａＳＯ４）、半水石膏（ＣａＳＯ４・０．５Ｈ２Ｏ）、二水石膏（ＣａＳＯ４・２Ｈ２Ｏ）等が挙げられる。
地盤改良材の質量に対する石膏（普通ポルトランドセメントに由来するものと、それ以外のものとの合計）の質量の割合としては、特に限定されるものではなく、例えば、７．８質量％以上２３．２質量％以下であることが好ましく、１１．７質量％以上１８．４質量％以下であることがより好ましい。
The ground improvement material may contain gypsum as a component other than ordinary Portland cement. The gypsum means something different from the components constituting ordinary Portland cement, and examples of the gypsum include anhydrous gypsum (CaSO 4 ), hemihydrate gypsum (CaSO 4 ·0.5H 2 O), and dihydrate gypsum (CaSO 4 ·2H 2 O).
The ratio of the mass of gypsum (the total of that derived from ordinary Portland cement and other substances) to the mass of the ground improvement material is not particularly limited, and is, for example, preferably 7.8 mass% or more and 23.2 mass% or less, and more preferably 11.7 mass% or more and 18.4 mass% or less.
本実施形態に係る地盤改良方法の対象土としては、特に限定されるものではなく、例えば、火山灰質粘性土等が挙げられる。該火山灰質粘性土は、水を含有する。具体的には、火山灰質粘性土としては、例えば、所謂、関東ローム、赤ぼく、黒ぼく等が挙げられる。より詳しくは、火山灰質粘性土は、地盤工学会基準「地盤材料の工学的分類方法（ＪＧＳ ００５１－２００９）」において火山灰に由来する火山灰質粘性土に分類される土質材料を意味する。なお、地盤工学会基準において火山灰質粘性土に分類される土質材料は、大分類で細粒土に属する。細粒土は、地盤工学会基準「地盤材料の工学的分類方法（ＪＧＳ ００５１－２００９）」において、土質材料の乾燥質量を１００質量％とした際に、粘土及びシルトを合わせて５０質量％以上含む土を意味し、言いかえれば、土質材料の乾燥質量を１００質量％とした際に、粒径０．０７５ｍｍ未満の粒子を５０質量％以上含む土を意味する。粒径０．０７５ｍｍ未満の粒子の割合は、ＪＩＳ Ａ １２０４：２００９「土の粒度試験方法」によって測定することができる。 The target soil for the ground improvement method according to this embodiment is not particularly limited, and examples thereof include volcanic ash clay soil. The volcanic ash clay soil contains water. Specifically, examples of volcanic ash clay soil include so-called Kanto loam, Akaboku, and Kuroboku. More specifically, volcanic ash clay soil refers to soil materials classified as volcanic ash clay soil derived from volcanic ash in the Geotechnical Society Standard "Engineering Classification Method for Ground Materials (JGS 0051-2009)." Note that soil materials classified as volcanic ash clay soil in the Geotechnical Society Standard belong to the broad classification of fine-grained soil. Fine-grained soil, according to the Geotechnical Society standard "Method of Engineering Classification of Geotechnical Materials (JGS 0051-2009)," refers to soil that contains 50% or more by weight of clay and silt combined, when the dry weight of the soil material is taken as 100% by weight. In other words, fine-grained soil refers to soil that contains 50% or more by weight of particles with a particle size of less than 0.075 mm, when the dry weight of the soil material is taken as 100% by weight. The proportion of particles with a particle size of less than 0.075 mm can be measured according to JIS A 1204:2009 "Method of testing for soil grain size."
本実施形態に係る地盤改良方法は、上記のように構成される地盤改良材（以下では、Ｎ型地盤改良材とも記す）と対象土と硫酸カリウムと水とを混合して改良土を形成する改良土形成工程と、該改良土で地盤を形成する地盤形成工程とを備える。
改良土形成工程では、「対象土の単位体積に対して混合するＮ型地盤改良材の質量（ｘ）」と、「対象土の単位体積に対して混合する硫酸カリウムの質量（ｙ）」との関係が下記（１）式を満たすように、対象土と地盤改良材と硫酸カリウムと水とを混合する。下記（１）式は、下記の実施例に記載の方法で得ることができる。
ｙ≧０．１２６５ｘ－１１．７２７・・・（１）
The ground improvement method of this embodiment includes an improved soil formation process in which the ground improvement material (hereinafter also referred to as N-type ground improvement material) configured as described above, target soil, potassium sulfate and water are mixed to form improved soil, and a ground formation process in which ground is formed with the improved soil.
In the improved soil formation process, the target soil, the soil improvement material, potassium sulfate, and water are mixed so that the relationship between "the mass (x) of the N-type soil improvement material to be mixed with the unit volume of the target soil" and "the mass (y) of potassium sulfate to be mixed with the unit volume of the target soil" satisfies the following formula (1). The following formula (1) can be obtained by the method described in the following examples.
y≧0.1265x-11.727...(1)
改良土を形成する際には、改良土中にＮ型地盤改良材を構成する成分全てが含まれればよく、例えば、Ｎ型地盤改良材が普通ポルトランドセメント以外の成分を含む場合、Ｎ型地盤改良材を構成する各成分を同時に（具体的には、各成分が混合された状態で）、対象土と混合してもよく、Ｎ型地盤改良材を構成する各成分を順次別々に、対象土と混合してもよい。 When forming improved soil, it is sufficient that all of the components constituting the N-type ground improvement material are contained in the improved soil. For example, if the N-type ground improvement material contains components other than ordinary Portland cement, each component constituting the N-type ground improvement material may be mixed with the target soil simultaneously (specifically, with each component mixed), or each component constituting the N-type ground improvement material may be mixed with the target soil in sequence and separately.
なお、本実施形態に係る地盤改良方法では、「対象土の単位体積に対して混合する硫酸カリウムの質量」を決定する際には、以下の方法を採用することができる。
なお、以下では、対象土とＮ型地盤改良材と硫酸カリウムと水とを混合して形成される改良土の強度を、「Ｎ型改良土強度」とも記す。
また、以下では、対象土の単位体積に対して混合するＮ型地盤改良材の質量を、「Ｎ型地盤改良材の混合質量」とも記す。
また、以下では、対象土の単位体積に対して混合する硫酸カリウムの質量を、「硫酸カリウムの混合質量」とも記す。
また、以下では、「Ｎ型地盤改良材の混合質量」に対する硫酸カリウムの混合質量の割合を、「硫酸カリウムの混合割合」とも記す。
また、以下では、早強ポルトランドセメントを主成分とする地盤改良材を、「Ｈ型地盤改良材」とも記す。
また、以下では、対象土と「Ｈ型地盤改良材」と水とを混合して形成される改良土の強度を、「Ｈ型改良土強度」とも記す。
In addition, in the ground improvement method according to this embodiment, the following method can be adopted when determining the "mass of potassium sulfate to be mixed per unit volume of the target soil."
In the following, the strength of the improved soil formed by mixing the target soil, N-type ground improvement material, potassium sulfate, and water will also be referred to as "N-type improved soil strength."
In addition, hereinafter, the mass of N-type ground improvement material to be mixed per unit volume of the target soil will also be referred to as the "mixed mass of N-type ground improvement material."
In the following, the mass of potassium sulfate to be mixed per unit volume of the target soil will also be referred to as the "mixed mass of potassium sulfate."
In addition, hereinafter, the ratio of the mixed mass of potassium sulfate to the "mixed mass of N-type ground improvement material" will also be referred to as the "mixed ratio of potassium sulfate."
In addition, below, the ground improvement material containing high-early-strength Portland cement as its main component will also be referred to as "H-type ground improvement material."
In addition, hereinafter, the strength of the improved soil formed by mixing the target soil, the "H-shaped ground improvement material", and water will also be referred to as "H-shaped improved soil strength".
まず初めに、「Ｎ型改良土強度」と、「硫酸カリウムの混合割合」と、の関係を示す散布図を作成する。該散布図は、「Ｎ型地盤改良材の混合質量」を変えて複数作成する。 First, create a scatter diagram showing the relationship between "N-type improved soil strength" and "mixing ratio of potassium sulfate." Create multiple scatter diagrams by changing the "mixing mass of N-type ground improvement material."
また、各散布図における「Ｎ型地盤改良材の混合質量」と同じ混合質量で「Ｈ型地盤改良材」を用いた際の改良土の強度（「Ｈ型改良土強度」）を求める。
なお、早強ポルトランドセメントとは、「ＪＩＳ Ｒ ５２１０：２００９ ポルトランドセメント」に規定される早強ポルトランドセメントをいう。
In addition, the strength of the improved soil ("H-type improved soil strength") is calculated when "H-type ground improvement material" is used with the same mixed mass as the "N-type ground improvement material mixed mass" in each scatter diagram.
The high-early-strength Portland cement refers to the high-early-strength Portland cement defined in "JIS R 5210:2009 Portland cement".
更に、各散布図において、「Ｈ型改良土強度に最も近いＮ型改良土強度の点（Ｐ）」と、「Ｈ型改良土強度を超え、且つ、（P）の強度に最も近いＮ型改良土強度の点」と、「Ｈ型改良土強度未満であり、且つ、（P）の強度に最も近いＮ型改良土強度の点」と、に基づいて、線形近似線を作成し、該線形近似線の数式（ｙ１＝α１×ｘ１＋β１）を求める。
そして、各散布図において、前記数式に基づいて、「Ｈ型改良土強度と同等のＮ型改良土強度（ｙ１）」が得られる際の「硫酸カリウムの混合割合（ｘ１）」を求める。
また、散布図毎に求めた「硫酸カリウムの混合割合（ｘ１）」と、各散布図における「Ｎ型地盤改良材の混合質量」とから、「硫酸カリウムの混合質量」を求める。つまり、Ｎ型地盤改良材の混合質量毎に、硫酸カリウムの混合質量を求める。
Furthermore, in each scatter plot, a linear approximation line is created based on "the point (P) of N-type improved soil strength closest to the H-type improved soil strength,""the point of N-type improved soil strength that exceeds the H-type improved soil strength and is closest to the strength of (P)," and "the point of N-type improved soil strength that is less than the H-type improved soil strength and is closest to the strength of (P)," and the formula for the linear approximation line (y1 = α1 × x1 + β1) is determined.
Then, for each scatter diagram, the "mixing ratio of potassium sulfate (x1)" that will give "N-type improved soil strength (y1) equivalent to H-type improved soil strength" is calculated based on the above formula.
In addition, the "mixed mass of potassium sulfate" is calculated from the "mixed ratio (x1) of potassium sulfate" calculated for each scatter diagram and the "mixed mass of N-type ground improvement material" in each scatter diagram. In other words, the mixed mass of potassium sulfate is calculated for each mixed mass of N-type ground improvement material.
そして、「硫酸カリウムの混合質量」と、「Ｎ型地盤改良材の混合質量」と、の関係を示す散布図を作成し、該散布図の線形近似線を示す数式（ｙ＝α×ｘ＋β）を作成する。
該線形近似線を示す数式は、Ｎ型改良土強度がＨ型改良土強度と同等になる際の、Ｎ型地盤改良材の混合質量と、硫酸カリウムの混合質量と、の関係を示したものとなる。
このため、「硫酸カリウムの混合質量」を決定する際に、斯かる線形近似線の数式を満たす「硫酸カリウムの混合質量」以上とすることにより、Ｈ型改良土強度以上のＮ型改良土強度を得ることができる。
Then, a scatter diagram is created showing the relationship between the "mixed mass of potassium sulfate" and the "mixed mass of N-type ground improvement material," and a formula (y = α x + β) is created that shows a linear approximation line of the scatter diagram.
The formula showing the linear approximation line shows the relationship between the mixed mass of N-type ground improvement material and the mixed mass of potassium sulfate when the strength of N-type improved soil becomes equivalent to the strength of H-type improved soil.
Therefore, when determining the "mixed mass of potassium sulfate," by selecting a mass equal to or greater than the "mixed mass of potassium sulfate" that satisfies the mathematical formula of the linear approximation line, it is possible to obtain an N-type improved soil strength equal to or greater than the H-type improved soil strength.
＜第二実施形態＞
以下、本発明の第二実施形態について説明する。第二実施形態に係る地盤改良方法は、Ｎ型地盤改良材と硫酸カリウムとを含む硫酸カリウム含有地盤改良材を用いる点で、第一実施形態と異なる。そこで、以下では、第一実施形態と異なる点について説明する。
Second Embodiment
The second embodiment of the present invention will be described below. The ground improvement method according to the second embodiment differs from the first embodiment in that a potassium sulfate-containing ground improvement material containing an N-type ground improvement material and potassium sulfate is used. Therefore, the following describes the differences from the first embodiment.
硫酸カリウム含有地盤改良材は、Ｎ型地盤改良材と硫酸カリウムとの合計質量に対する硫酸カリウムの質量の割合（ｚ）が下記（２）式を満たす。ｘは、第一実施形態のＮ型地盤改良材の混合質量であり、ｙは、第一実施形態の硫酸カリウムの混合質量である。
ｚ≧ｙ／（ｘ＋ｙ）×１００・・・（２）
（ｘ：対象土の単位体積に対して混合する地盤改良材の質量）
（ｙ＝０．１２６５ｘ－１１．７２７）
The potassium sulfate-containing ground improvement material has a ratio (z) of the mass of potassium sulfate to the total mass of the N-type ground improvement material and potassium sulfate that satisfies the following formula (2): x is the mixed mass of the N-type ground improvement material of the first embodiment, and y is the mixed mass of the potassium sulfate of the first embodiment.
z≧y/(x+y)×100...(2)
(x: mass of ground improvement material to be mixed per unit volume of target soil)
(y=0.1265x-11.727)
以上のように、本発明に係る地盤改良方法、及び、硫酸カリウム含有地盤改良材は、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成された改良土と同等の強度を発現する改良土を形成することができる。また、本発明に係る改良土は、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成された改良土と同等の強度を発現する。 As described above, the ground improvement method and potassium sulfate-containing ground improvement material of the present invention can form improved soil that exhibits the same strength as improved soil formed using a ground improvement material whose main component is high-early-strength Portland cement. Furthermore, the improved soil of the present invention exhibits the same strength as improved soil formed using a ground improvement material whose main component is high-early-strength Portland cement.
即ち、上記の地盤改良方法は、対象土と地盤改良材とを混合して改良土を形成する地盤改良方法であって、対象土と地盤改良材と硫酸カリウムとを混合して改良土を形成する改良土形成工程を備えており、地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、改良土形成工程では、対象土の単位体積に対して混合する地盤改良材の質量（ｘ）と、対象土の単位体積に対して混合する硫酸カリウムの質量（ｙ）との関係が下記（１）式を満たすように、対象土と地盤改良材と硫酸カリウムとを混合する。これにより、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成した改良土と同等の強度を発現する改良土を形成することができる。
ｙ≧０．１２６５ｘ－１１．７２７・・・（１）
That is, the above-mentioned ground improvement method is a ground improvement method for forming improved soil by mixing the target soil with a ground improvement material, and includes an improved soil formation step for forming improved soil by mixing the target soil with the ground improvement material and potassium sulfate, the ground improvement material containing ordinary Portland cement as a main component, and in the improved soil formation step, the target soil, the ground improvement material and potassium sulfate are mixed so that the relationship between the mass (x) of the ground improvement material mixed with respect to a unit volume of the target soil and the mass (y) of potassium sulfate mixed with respect to a unit volume of the target soil satisfies the following formula (1). This makes it possible to form improved soil that exhibits the same strength as improved soil formed using a ground improvement material containing high-early-strength Portland cement as a main component.
y≧0.1265x-11.727...(1)
また、対象土の単位体積に対して混合する地盤改良材の質量（ｘ）に対する対象土の単位体積に対して混合する硫酸カリウムの質量（ｙ）の割合が６．６質量％以上であることが好ましい。これにより、より良好な強度を発現する改良土を形成することができる。 It is also preferable that the ratio of the mass (y) of potassium sulfate to be mixed per unit volume of the target soil to the mass (x) of the ground improvement material to be mixed per unit volume of the target soil is 6.6 mass% or more. This allows the formation of improved soil that exhibits better strength.
また、上記の硫酸カリウム含有地盤改良材は、対象土と混合されて改良土を形成する地盤改良材と、硫酸カリウムとを含んでおり、地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、地盤改良材と硫酸カリウムとの合計質量に対する硫酸カリウムの質量割合（ｚ）は、下記（２）式を満たす。これにより、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成した改良土と同等の強度を発現する改良土を形成することができる。
ｚ≧ｙ／（ｘ＋ｙ）×１００・・・（２）
（ｘ：対象土の単位体積に対して混合する地盤改良材の質量）
（ｙ＝０．１２６５ｘ－１１．７２７）
The potassium sulfate-containing ground improvement material contains potassium sulfate and a ground improvement material that is mixed with the target soil to form improved soil, the ground improvement material contains ordinary Portland cement as a main component, and the mass ratio (z) of potassium sulfate to the total mass of the ground improvement material and potassium sulfate satisfies the following formula (2). This makes it possible to form improved soil that exhibits the same strength as improved soil formed using a ground improvement material containing high-early-strength Portland cement as a main component.
z≧y/(x+y)×100...(2)
(x: mass of ground improvement material to be mixed per unit volume of target soil)
(y=0.1265x-11.727)
上記の改良土は、対象土と地盤改良材と硫酸カリウムとを含む改良土であって、地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、対象土の単位体積に対して混合される地盤改良材の質量（ｘ）と、対象土の単位体積に対して混合される硫酸カリウムの質量（ｙ）との関係が下記（１）式を満たす。これにより、早強ポルトランドセメントを主成分とする地盤改良材を用いて形成した改良土と同等の強度を発現させることができる。
ｙ≧０．１２６５ｘ－１１．７２７・・・（１）
The improved soil is an improved soil containing target soil, a ground improvement material, and potassium sulfate, the ground improvement material containing ordinary Portland cement as a main component, and the relationship between the mass (x) of the ground improvement material mixed with a unit volume of the target soil and the mass (y) of potassium sulfate mixed with a unit volume of the target soil satisfies the following formula (1). This allows the improved soil to exhibit the same strength as improved soil formed using a ground improvement material containing high-early-strength Portland cement as a main component.
y≧0.1265x-11.727...(1)
なお、本発明に係る地盤改良方法、硫酸カリウム含有地盤改良材、及び、改良土は、上記実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲で種々の変更が可能である。また、上記した複数の実施形態の構成や方法等を任意に採用して組み合わせてもよく（１つの実施形態に係る構成や方法等を他の実施形態に係る構成や方法等に適用してもよく）、さらに、下記する各種の変更例に係る構成や方法等を任意に選択して、上記した実施形態に係る構成や方法等に採用してもよいことは勿論である。 The ground improvement method, potassium sulfate-containing ground improvement material, and improved soil according to the present invention are not limited to the above-mentioned embodiment, and various modifications are possible without departing from the gist of the present invention. In addition, the configurations and methods of the above-mentioned embodiments may be arbitrarily adopted and combined (the configurations and methods of one embodiment may be applied to the configurations and methods of other embodiments), and further, the configurations and methods of the various modified examples described below may be arbitrarily selected and adopted in the configurations and methods of the above-mentioned embodiments.
以下、実施例を用いて本発明を更に具体的に説明するが、本発明は、以下の実施例に限定されるものではない。 The present invention will be explained in more detail below using examples, but the present invention is not limited to the following examples.
＜使用材料＞
・地盤改良材Ｉ（Ｎ型地盤改良材）
普通ポルトランドセメント（質量）：無水石膏（質量）＝８３：１７
・地盤改良材ＩＩ（Ｈ型地盤改良材）
早強ポルトランドセメント（質量）：無水石膏（質量）＝８３：１７
・対象土
関東ローム（湿潤密度：１．３９３ｇ／ｃｍ３、自然含水比：１１２．３％）
・硫酸カリウム（特級試薬）
<Materials used>
・Soil improvement material I (N type ground improvement material)
Ordinary Portland cement (by weight): anhydrous gypsum (by weight) = 83:17
・Soil improvement material II (H type ground improvement material)
High early strength Portland cement (mass): anhydrous gypsum (mass) = 83:17
Target soil: Kanto loam (wet density: 1.393 g/cm 3 , natural water content: 112.3%)
・Potassium sulfate (special grade reagent)
＜供試体の作製＞
上記の各材料を用いて、下記表１の配合で改良土を作製し、該改良土を用いて、ＪＧＳ ０８２１「安定処理土の締固めをしない供試体作製方法」に準拠した供試体を作製した。該供試体は、２０℃、９５％ＲＨの条件で封緘養生した。
<Preparation of test specimen>
The above materials were used to prepare improved soil according to the composition shown in Table 1 below, and the improved soil was used to prepare test specimens in accordance with JGS 0821 "Test specimen preparation method for stabilized soil without compaction." The test specimens were sealed and cured under conditions of 20°C and 95% RH.
＜一軸圧縮強さ＞
得られた供試体（材齢２８日）について、ＪＩＳ Ａ １２１６に準拠して一軸圧縮試験を行い、一軸圧縮強さ（Ｎ型改良土強度、及び、Ｈ型改良土強度）を求めた。一軸圧縮強さについては、下記表１に示す。
<Uniaxial compressive strength>
The obtained specimens (28 days old) were subjected to an unconfined compression test in accordance with JIS A 1216 to determine the unconfined compressive strength (N-type improved soil strength and H-type improved soil strength). The unconfined compressive strength is shown in Table 1 below.
＜散布図の作製Ｉ＞
Ｎ型地盤改良材を用いた各供試体（改良土）の「Ｎ型改良土強度」と、Ｎ型地盤改良材を用いた各供試体（改良土）の「硫酸カリウムの混合割合」と、の関係を示す散布図を作成した。また、該散布図は、「Ｎ型地盤改良材の混合質量」毎に作成した。各散布図は、図１（ａ）～（ｃ）に示す。
また、各散布図における線形近似線を求めた。具体的には、各散布図において、「Ｈ型改良土強度に最も近いＮ型改良土強度の点（P）」と、「Ｈ型改良土強度を超え、且つ、（P）の強度に最も近いＮ型改良土強度の点」と、「Ｈ型改良土強度未満であり、且つ、（P）の強度に最も近いＮ型改良土強度の点」と、に基づいて（即ち、図１（ａ）～（ｃ）それぞれの白抜きの３点に基づいて）、線形近似線を作成し、該線形近似線の数式（ｙ１＝α１×ｘ１＋β１）を求めた。線形近似線の数式については、図１（ａ）～（ｃ）に示す。
<Creating a scatter diagram I>
A scatter diagram was created showing the relationship between the "N-type improved soil strength" of each test specimen (improved soil) using the N-type ground improvement material and the "mixing ratio of potassium sulfate" of each test specimen (improved soil) using the N-type ground improvement material. In addition, the scatter diagram was created for each "mixing mass of N-type ground improvement material." Each scatter diagram is shown in Figure 1 (a) to (c).
In addition, a linear approximation line was obtained for each scatter diagram. Specifically, a linear approximation line was created based on "point (P) of N-type improved soil strength closest to H-type improved soil strength,""point of N-type improved soil strength exceeding H-type improved soil strength and closest to the strength of (P)," and "point of N-type improved soil strength less than H-type improved soil strength and closest to the strength of (P)" (i.e., based on the three white points in each of Figures 1(a) to (c)), and the formula of the linear approximation line (y1 = α1 x x1 + β1) was obtained. The formula of the linear approximation line is shown in Figures 1(a) to (c).
＜散布図の作製ＩＩ＞
上記の各散布図において、Ｈ型地盤改良材を用いた供試体（改良土）の「Ｈ型改良土強度」に相当する「Ｎ型改良土強度（ｙ１）」が得られる際の「硫酸カリウムの混合割合（ｘ１）」を、各散布図の線形近似線に基づいて求めた。「硫酸カリウムの混合割合（ｘ１）」は、下記表２に示す。
また、得られた「硫酸カリウムの混合割合（ｘ１）」と「Ｎ型地盤改良材の混合質量」とから、Ｈ型改良土強度に相当するＮ型改良土強度が得られる際の「硫酸カリウムの混合質量」を求めた。「硫酸カリウムの混合質量」は、下記表２に示す。
そして、得られた「硫酸カリウムの混合質量」と「Ｎ型地盤改良材の混合質量」との関係を示す散布図を作成し、該散布図の線形近似線を求めた。散布図及び線形近似線の数式については、図２に示す。
<Creating a scatter diagram II>
In each of the above scatter diagrams, the "mixing ratio of potassium sulfate (x1)" when the "N-type improved soil strength (y1)" equivalent to the "H-type improved soil strength" of the test specimen (improved soil) using the H-type ground improvement material was obtained was calculated based on the linear approximation line of each scatter diagram. The "mixing ratio of potassium sulfate (x1)" is shown in Table 2 below.
In addition, the "mixed mass of potassium sulfate" was calculated from the obtained "mixed ratio of potassium sulfate (x1)" and the "mixed mass of N-type ground improvement material" when the N-type improved soil strength equivalent to the H-type improved soil strength was obtained. The "mixed mass of potassium sulfate" is shown in Table 2 below.
Then, a scatter diagram showing the relationship between the obtained "mixed mass of potassium sulfate" and the "mixed mass of N-type ground improvement material" was created, and a linear approximation line of the scatter diagram was obtained. The formula of the scatter diagram and the linear approximation line is shown in FIG. 2.
＜まとめ＞
図２の線形近似線を示す数式（ｙ＝０．１２６５ｘ－１１．７２７）は、Ｎ型改良土強度がＨ型改良土強度と同等になる際の、「Ｎ型地盤改良材の混合質量」と、「硫酸カリウムの混合質量」との関係を示したものとなる。
このため、対象土と混合する「硫酸カリウムの混合質量」を決定する際に、斯かる線形近似線の数式を満たす「硫酸カリウムの混合質量（ｙ）」以上とすることにより（即ち、ｙ≧０．１２６５ｘ－１１．７２７を満たすようにすることで）、Ｈ型改良土強度以上のＮ型改良土強度を得ることができる。
<Summary>
The formula (y = 0.1265x - 11.727) showing the linear approximation line in Figure 2 shows the relationship between the "mixed mass of N-type ground improvement material" and the "mixed mass of potassium sulfate" when the strength of N-type improved soil becomes equivalent to the strength of H-type improved soil.
Therefore, when determining the "mixed mass of potassium sulfate" to be mixed with the target soil, by making it equal to or greater than the "mixed mass of potassium sulfate (y)" that satisfies the mathematical formula for the linear approximation line (i.e., by making it satisfy y≧0.1265x−11.727), it is possible to obtain an N-type improved soil strength that is equal to or greater than the H-type improved soil strength.
Claims (4)
対象土と地盤改良材と硫酸カリウムとを混合して改良土を形成する改良土形成工程を備えており、
地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、
改良土形成工程では、対象土の単位体積に対して混合する地盤改良材の質量（ｘ、単位：ｋｇ／ｍ３）と、
対象土の単位体積に対して混合する硫酸カリウムの質量（ｙ、単位：ｋｇ／ｍ３）との関係が下記（１）式を満たすように、対象土と地盤改良材と硫酸カリウムとを混合し、
地盤改良材は、普通ポルトランドセメント以外の成分として石膏を含み、地盤改良材の質量に対する石膏の質量の割合が７．８質量％以上２３．２質量％以下であり、
対象土が、火山灰質粘性土である、
地盤改良方法。
ｙ≧０．１２６５ｘ－１１．７２７・・・（１）
A ground improvement method for forming improved soil by mixing a target soil with a ground improvement material,
The method includes a step of forming improved soil by mixing the target soil, the ground improvement material, and potassium sulfate to form improved soil.
Ground improvement materials contain ordinary Portland cement as their main component.
In the improved soil formation process, the mass of the ground improvement material to be mixed with respect to the unit volume of the target soil (x, unit: kg/m 3 );
The target soil, the ground improvement material, and potassium sulfate are mixed so that the relationship between the mass of potassium sulfate (y, unit: kg/m 3 ) to be mixed per unit volume of the target soil satisfies the following formula (1):
The ground improvement material contains gypsum as a component other than ordinary Portland cement, and the ratio of the mass of the gypsum to the mass of the ground improvement material is 7.8 mass% or more and 23.2 mass% or less,
The target soil is volcanic ash clay soil .
Ground improvement methods.
y≧0.1265x-11.727...(1)
請求項１に記載の地盤改良方法。
The ratio of the mass (y, unit: kg/m 3 ) of potassium sulfate to be mixed with a unit volume of the target soil to the mass (x, unit: kg/m 3 ) of the ground improvement material to be mixed with a unit volume of the target soil is 6.6 mass% or more;
The ground improvement method according to claim 1.
地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、
地盤改良材と硫酸カリウムとの合計質量に対する硫酸カリウムの質量割合（ｚ、単位：質量％）は、下記（２）式を満たし、
地盤改良材は、普通ポルトランドセメント以外の成分として石膏を含み、地盤改良材の質量に対する石膏の質量の割合が７．８質量％以上２３．２質量％以下であり、
対象土が、火山灰質粘性土である、
硫酸カリウム含有地盤改良材。
ｚ≧ｙ／（ｘ＋ｙ）×１００・・・（２）
（ｘ：対象土の単位体積に対して混合する地盤改良材の質量、単位：ｋｇ／ｍ３）
（ｙ＝０．１２６５ｘ－１１．７２７、ｙの単位：ｋｇ／ｍ３）
The method includes mixing the target soil with a ground improvement material to form improved soil, and potassium sulfate.
Ground improvement materials contain ordinary Portland cement as their main component.
The mass ratio of potassium sulfate to the total mass of the ground improvement material and potassium sulfate (z, unit: mass%) satisfies the following formula (2):
The ground improvement material contains gypsum as a component other than ordinary Portland cement, and the ratio of the mass of the gypsum to the mass of the ground improvement material is 7.8 mass% or more and 23.2 mass% or less,
The target soil is volcanic ash clay soil .
A ground improvement material containing potassium sulfate.
z≧y/(x+y)×100...(2)
(x: mass of ground improvement material to be mixed per unit volume of target soil, unit: kg/ m3 )
(y=0.1265x-11.727, unit of y: kg/ m3 )
地盤改良材は、普通ポルトランドセメントを主成分として含んでおり、
対象土の単位体積に対して混合される地盤改良材の質量（ｘ、単位：ｋｇ／ｍ３）と、対象土の単位体積に対して混合される硫酸カリウムの質量（ｙ、単位：ｋｇ／ｍ３）との関係が下記（１）式を満たし、
地盤改良材は、普通ポルトランドセメント以外の成分として石膏を含み、地盤改良材の質量に対する石膏の質量の割合が７．８質量％以上２３．２質量％以下であり、
対象土が、火山灰質粘性土である、
改良土。
ｙ≧０．１２６５ｘ－１１．７２７・・・（１） An improved soil containing a target soil, a ground improvement material, and potassium sulfate,
Ground improvement materials contain ordinary Portland cement as their main component.
The relationship between the mass of the ground improvement material (x, unit: kg/m 3 ) mixed with respect to a unit volume of the target soil and the mass of potassium sulfate (y, unit: kg/m 3 ) mixed with respect to a unit volume of the target soil satisfies the following formula (1):
The ground improvement material contains gypsum as a component other than ordinary Portland cement, and the ratio of the mass of the gypsum to the mass of the ground improvement material is 7.8 mass% or more and 23.2 mass% or less,
The target soil is volcanic ash clay soil .
Improved soil.
y≧0.1265x-11.727...(1)
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| JP2014152223A (en) | 2013-02-07 | 2014-08-25 | Sumitomo Osaka Cement Co Ltd | Ground improvement material, assistant for ground improvement and ground improvement method |
| JP2018171744A (en) | 2017-03-31 | 2018-11-08 | 住友大阪セメント株式会社 | Method of placing cement mixture |
| JP2019178274A (en) | 2018-03-30 | 2019-10-17 | 住友大阪セメント株式会社 | Foundation improver, improved soil and production method of improved soil |
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| JP2014152223A (en) | 2013-02-07 | 2014-08-25 | Sumitomo Osaka Cement Co Ltd | Ground improvement material, assistant for ground improvement and ground improvement method |
| JP2018171744A (en) | 2017-03-31 | 2018-11-08 | 住友大阪セメント株式会社 | Method of placing cement mixture |
| JP2019178274A (en) | 2018-03-30 | 2019-10-17 | 住友大阪セメント株式会社 | Foundation improver, improved soil and production method of improved soil |
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