JP4235772B2 - Alkaline environment diffusion prevention method - Google Patents

Alkaline environment diffusion prevention method Download PDF

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JP4235772B2
JP4235772B2 JP29340097A JP29340097A JP4235772B2 JP 4235772 B2 JP4235772 B2 JP 4235772B2 JP 29340097 A JP29340097 A JP 29340097A JP 29340097 A JP29340097 A JP 29340097A JP 4235772 B2 JP4235772 B2 JP 4235772B2
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alkaline environment
improved soil
lime
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JPH11116953A (en
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俊也 岡田
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Obayashi Corp
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    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B3/00—Fertilisers based essentially on di-calcium phosphate
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B1/00—Superphosphates, i.e. fertilisers produced by reacting rock or bone phosphates with sulfuric or phosphoric acid in such amounts and concentrations as to yield solid products directly
    • C05B1/02—Superphosphates
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B7/00—Fertilisers based essentially on alkali or ammonium orthophosphates

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  • Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
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Description

【０００１】
【発明の属する技術分野】
本発明は、セメント・石灰等で処理された改良土のアルカリ成分の拡散を防止する方法に関する。
【０００２】
【従来の技術】
場所打ち杭や地中連続壁といった基礎工事あるいはシールドトンネル工事においては、建設泥土が多量に発生する。また、水質汚染を防止するため、その原因となるヘドロ層を浚渫によって除去することがあるが、かかる浚渫工事においても浚渫泥土が多量に発生する。
【０００３】
このような発生土は、従来であれば脱水、ｐＨ処理といった処理を経た後、産業廃棄物として処分されることが多かったが、資源の有効利用や環境保護あるいは処分コストの低減といった観点から言えば、できるだけ再利用されることが望ましい。
【０００４】
このような背景の下、最近では、発生土にセメント系材料または石灰系材料を添加混合して強度を改善し、かかる改良土を盛土材、斜面形成材、遮水壁の構築材あるいは裏込め等の空洞充填材として有効利用されることが多くなってきた。
【０００５】
【発明が解決しようとする課題】
ここで、かかる改良土が使用された箇所では、セメント系材料や石灰系材料が添加されている関係上、改良土に含まれるアルカリ分が周囲に拡散して植物の正常な発育を阻害するおそれがあるという問題を生じていた。
【０００６】
かかる対策として、従来、アルカリ中和能の高い関東ロームや赤土などを改良土に覆土したりその下に敷設したりしていたが、かかる種類の土は、必ずしも妥当な価格で調達できるとは限らず、緑化対策に高いコストを強いられることは少なくなかった。
【０００７】
本発明は、上述した事情を考慮してなされたもので、改良土内のアルカリ分が周囲に拡散するのを防止可能なアルカリ環境の拡散防止方法を提供することを目的とする。
【０００８】
【課題を解決するための手段】
上記目的を達成するため、本発明に係るアルカリ環境の拡散防止方法は請求項１に記載したように、セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置するアルカリ環境の拡散防止方法であって、地盤を掘削して形成された埋設領域の内面に前記薬剤を予め敷設し、次いで、該薬剤で内面が敷設された前記埋設領域内に前記改良土を投入し、次いで、前記改良土の上に前記薬剤を散布するものである。
【０００９】
また、本発明に係るアルカリ環境の拡散防止方法は請求項２に記載したように、セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置するアルカリ環境の拡散防止方法であって、地盤の上に前記薬剤を予め敷設し、その上に前記改良土を盛土した後、前記薬剤を散布するものである。
【００１０】
また、本発明に係るアルカリ環境の拡散防止方法は請求項３に記載したように、セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置するアルカリ環境の拡散防止方法であって、止水壁を不透水層に到達させる形で施工し、前記止水壁で囲まれた領域内に前記改良土を埋設し、その上に前記薬剤を含む表層を施工するものである。
【００１１】
また、本発明に係るアルカリ環境の拡散防止方法は、前記薬剤を燐酸系若しくは硫酸系化学肥料とするものである。
また、本発明に係るアルカリ環境の拡散防止方法は、前記薬剤を過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウムとするものである。
また、本発明に係るアルカリ環境の拡散防止方法は、前記薬剤を通常の土に混ぜて使用するものである。
また、本発明に係るアルカリ環境の拡散防止方法は請求項７に記載したように、セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置するアルカリ環境の拡散防止方法であって、前記薬剤を通常の土に混ぜて使用するものである。
【００１２】
本発明に係るアルカリ環境の拡散防止方法においては、セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置する。
【００１３】
このようにすると、配置された薬剤は、改良土内から浸出してきたアルカリ分である水酸化カルシウムと反応して難溶性の塩を形成するので、水酸化カルシウムが水酸化イオンの形で周囲に拡散することはない。すなわち、配置された薬剤は、改良土内の水酸化カルシウムが周囲に拡散するのを防止する拡散防止層として機能する。
【００１４】
本発明で言うところの包囲とは、止水壁や不透水層との組み合わせによる部分的な包囲をも含むものとする。
【００１５】
薬剤を配置するにあたって、その配置時期としては、改良土を盛土等の形で施工した後でその上に散布する、改良土を施工する前に予め敷設したり、埋設領域や廃棄物処分場の廃棄領域の内面に予め敷設しておくなどの方法が考えられる。
【００１６】
また、配置方法として薬剤をそのまま使用するようにしてもよいが、マサ土や砂質土といった通常の土と混合した状態で使用するならば、アルカリ中和能のない土に対してもアルカリ分の拡散を防ぐ機能を持たせることが可能となる。
【００１７】
薬剤としては、改良土に含まれる水酸化カルシウムと反応して難溶性の塩を形成するものであればどのようなものでもよいが、該薬剤を燐酸系若しくは硫酸系化学肥料とするならば、比較的入手が容易で安全性も高く、過剰散布による影響も少ない。
【００１８】
特に、前記薬剤を過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウムとするならば、電気伝導度（ＥＣ）をあまり上昇させることなく、ｐＨを１０程度に下げることが可能となり、植物の成長に適した環境を作り出すことができる。
【００１９】
【発明の実施の形態】
以下、本発明に係るアルカリ環境の拡散防止方法の実施の形態について、添付図面を参照して説明する。なお、従来技術と実質的に同一の部品等については同一の符号を付してその説明を省略する。
【００２０】
図１は、本実施形態に係るアルカリ環境の拡散防止方法を示した略図である。同図でわかるように、本実施形態に係るアルカリ環境の拡散防止方法においては、まず、同図に示すように、地盤１を掘削して形成された埋設領域の内面に薬剤、特に燐酸系若しくは硫酸系化学肥料としての過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム２を予め敷設する。
【００２１】
次に、過燐酸石灰等で内面が敷設された埋設領域内にセメント系材料もしくは石灰系材料で処理された改良土３を投入する。次に、改良土３の上に前述したと同様の燐酸系若しくは硫酸系化学肥料としての過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム４を散布する。
【００２２】
このようにすると、改良土３は、過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム２、４で包囲された格好となり、かかる過燐酸石灰等は、改良土３内から浸出してきたアルカリ分である水酸化カルシウムと反応して難溶性の塩を形成し、その流動性を低下させて該反応位置にとどまらせる。
【００２３】
すなわち、過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム２、４は、改良土３内の水酸化カルシウムが周囲に拡散するのを防止する拡散防止層として機能する。
【００２４】
以上説明したように、本実施形態に係るアルカリ環境の拡散防止方法によれば、改良土３に含まれている水酸化カルシウムが周囲に浸出しても、それを包囲するように配置された過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム２、４といった薬剤と反応して難溶性の塩を形成するので、水酸化カルシウムは、水酸化イオンの形で周囲に拡散することはない。また、難溶性の塩となるため、流動性が低下して該反応位置にとどまる可能性が高くなり、水酸化カルシウムの拡散を物理的にも防止する。したがって、改良土３の周囲を緑化に適した環境に維持することが可能となる。
【００２５】
また、本実施形態によれば、薬剤として燐酸系若しくは硫酸系化学肥料を用いるようにしたので、入手が容易であるとともに、散布を行う作業員には特別な資格が必要とされない。また、散布時の安全性が高く、しかも過剰散布の場合の悪影響が少ない。
【００２６】
また、本実施形態によれば、かかる化学肥料として、特に過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウムを使用するようにしたので、後述するように、電気伝導度ＥＣをあまり上昇させることなく、ｐＨを１０程度に下げることが可能となり、ほとんどの植物を生育させる環境を改良土の周囲に作り出すことができる。
【００２７】
図２は、本実施形態に係るアルカリ環境の拡散防止方法における作用効果を確認した実験の結果を示したグラフである。同グラフに示す実験は、過燐酸石灰、重過燐酸石灰、硫酸マグネシウム、硫酸カリ苦土をそれぞれ改良土に添加してｐＨの低下状況を調べた結果であり、同グラフから、硫酸カリ苦土を除く上述の３つの薬剤については、単位容積当たりの添加量を２〜５重量％程度添加することによって、ｐＨが１０程度まで低下していることがわかる。
【００２８】
また、同グラフ(b)に示す実験は、同じケースについて電気伝導度ＥＣの増加状況を調べた結果であり、同グラフからは、上述した添加量の下では、電気伝導度ＥＣが２ｍｓ／ｃｍ程度までしか上昇せず、植物の成長にはほとんど影響しないであろうことが考察される。
【００２９】
これらのグラフから得られた結果の原因として、過燐酸石灰若しくは重過燐酸石灰の場合については、それらに含まれている燐酸成分と水酸化カルシウムとが
Ｈ3ＰＯ4＋Ｃａ(ＯＨ)2 →ＣａＨＰＯ4＋２Ｈ2Ｏ
または
２Ｈ3ＰＯ4＋３Ｃａ(ＯＨ)2 →Ｃａ3(ＰＯ4)2＋６Ｈ2Ｏ
という形で反応して、水酸化カルシウムが難溶性のＣａＨＰＯ4あるいはＣａ3(ＰＯ4)2 と水に変化し、ｐＨが低下したものと予想される。
【００３０】
また、硫酸マグネシウムの場合については、
ＭｇＳＯ4 ＋ Ｃａ(ＯＨ)2 → Ｍｇ(ＯＨ)2 ＋ ＣａＳＯ4
という形で反応し、水酸化イオンが難溶性であるＭｇ(ＯＨ)2 に取り込まれることとなって、ｐＨが低下したものと予想される。
【００３１】
表１は、本実施形態に係るアルカリ環境の拡散防止方法における作用効果を実際の植物について確認した実験結果を示した表である。
【００３２】
【表１】

Figure 0004235772
同表に示す実験は、薬剤を添加しない場合をはじめ、過燐酸石灰、重過燐酸石灰、硫酸マグネシウム、硫酸カリ苦土をそれぞれ添加した合計５ケースについてそれぞれ添加量を変化させてコマツナの生育状況を調べた結果であり、同表からは、過燐酸石灰、重過燐酸石灰及び硫酸マグネシウムを添加した改良土については、コマツナの生育状況について明らかな改善効果が見られる。なお、本実験では、改良土内のアルカリ成分が植物の成長にもっとも影響を与える結果となるよう、改良土の水分を飽和状態として行った。
【００３３】
本実施形態では、埋立材に使用される改良土３について本発明を適用した例を説明したが、本発明は、改良土の用途について限定するものではなく、埋立材以外にも盛土、堤体材等にも使用することができる。図３(a)は、地盤１の上に燐酸系若しくは硫酸系化学肥料としての過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム２を予め敷設し、その上に改良土３を盛土した後、同様の過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム４を散布した例を示したものである。
【００３４】
かかる構成においても、改良土３は、過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム２、４で包囲された格好となるので、詳細な説明は省略するが上述したとほぼ同様の効果を奏する。
【００３５】
また、同図(b)に示すように、止水壁１２を不透水層１１に到達させる形で施工しておき、該止水壁１２で囲まれた領域内に改良土３を埋設する。そして、その上に過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム等を含む表層５を施工する。
【００３６】
かかる構成においても、改良土３は、その側方については不透水層で、上方については過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム４を含む表層５で包囲された格好となるので、上述したと同様、改良土３から浸出してきたアルカリ分は表層５内で難溶性の塩を形成し、水酸化イオンとして地表面まで浸出してくるおそれがなくなる。
【００３７】
そのため、地表面近傍は、改良土３のアルカリ分の影響を受けることなく、適度なｐＨに維持することが可能となり、所望の緑化を施すことが可能となる。
【００３８】
なお、上述の実施形態並びに各変形例では特に言及しなかったが、薬剤の使用方法として、過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム等をそのまま散布等の方法で使用する以外に、マサ土や砂質土といった通常の土に混ぜて使用するようにしてもよい。
【００３９】
かかる構成によれば、アルカリ中和能のない土についてもアルカリ分の拡散を防ぐ機能を持たせることが可能となる。
【００４０】
【発明の効果】
以上述べたように、本発明のアルカリ環境の拡散防止方法によれば、改良土に含まれている水酸化カルシウムが周囲に浸出しても、それを包囲するように配置された薬剤と反応して難溶性の塩を形成するので、水酸化カルシウムは、水酸化イオンとして周囲に拡散することはない。したがって、改良土の周囲を緑化に適した環境に維持することが可能となる。
【００４１】
また、請求項４に係る本発明のアルカリ環境の拡散防止方法によれば、入手が容易であるとともに、散布を行う作業員には特別な資格が必要とされない。また、散布時の安全性が高く、しかも過剰散布の場合の悪影響が少ないという効果も奏する。
【００４２】
また、請求項５に係る本発明のアルカリ環境の拡散防止方法によれば、電気伝導度ＥＣをあまり上昇させることなく、ｐＨを１０程度に下げることが可能となり、ほとんどの植物を生育させる環境を作り出すことができるという効果も奏する。
【００４３】
また、請求項６，７に係る本発明のアルカリ環境の拡散防止方法によれば、アルカリ中和能のない土についてもアルカリ分の拡散を防ぐ機能を持たせることが可能となるという効果も奏する。
【００４４】
【図面の簡単な説明】
【図１】本実施形態に係るアルカリ環境の拡散防止方法の略図。
【図２】本実施形態に係るアルカリ環境の拡散防止方法の作用を示すグラフ。
【図３】変形例に係るアルカリ環境の拡散防止方法の略図。
【符号の説明】
３ 改良土
２、４ 過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウム
（燐酸系若しくは硫酸系化学肥料、薬剤）
５ 過燐酸石灰等を含む表層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preventing the diffusion of alkali components in improved soil treated with cement, lime or the like.
[0002]
[Prior art]
In foundation works such as cast-in-place piles and underground continuous walls or shield tunnel works, a large amount of construction mud is generated. In addition, in order to prevent water pollution, the sludge layer that causes it may be removed by dredging, but dredging mud is also generated in such dredging work.
[0003]
Conventionally, such generated soil is often disposed of as industrial waste after dehydration and pH treatment, but it can be said from the viewpoint of effective use of resources, environmental protection, or reduction of disposal costs. If possible, it should be reused as much as possible.
[0004]
Against this background, recently, cement-based materials or lime-based materials are added and mixed with the generated soil to improve the strength, and such improved soil is used as embankment material, slope forming material, construction material for impermeable walls or backfilling. It has been increasingly used effectively as a cavity filler.
[0005]
[Problems to be solved by the invention]
Here, in places where such improved soil is used, there is a risk that the alkali content in the improved soil will diffuse to the surroundings and hinder the normal growth of plants due to the addition of cement-based materials and lime-based materials. There was a problem that there was.
[0006]
Conventionally, Kanto loam and red soil with high alkali neutralizing ability have been covered with improved soil or laid under such soil. However, this kind of soil is not necessarily procured at a reasonable price. Not limited to this, there were many cases where high costs were required for greening countermeasures.
[0007]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an alkaline environment diffusion prevention method capable of preventing the alkali content in the improved soil from diffusing around.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the alkaline environment diffusion prevention method according to the present invention reacts with calcium hydroxide contained in the improved soil treated with a cement-based material or a lime-based material as described in claim 1. A method for preventing diffusion of an alkaline environment in which a drug that forms a sparingly soluble salt is disposed so as to surround the improved soil, wherein the drug is preliminarily laid on the inner surface of a buried region formed by excavating the ground. Then, the improved soil is put into the buried region where the inner surface is laid with the chemical, and then the chemical is sprayed on the improved soil.
[0009]
In addition, the alkaline environment diffusion preventing method according to the present invention, as described in claim 2, is a hardly soluble salt by reacting with calcium hydroxide contained in improved soil treated with a cement-based material or a lime-based material. A method for preventing diffusion of an alkaline environment in which a chemical forming a material is disposed so as to surround the improved soil, wherein the chemical is preliminarily laid on the ground, and the improved soil is embanked, and then the chemical is To disperse.
[0010]
The alkaline environment diffusion prevention method according to the present invention, as described in claim 3, is a hardly soluble salt by reacting with calcium hydroxide contained in improved soil treated with a cement-based material or a lime-based material. A method for preventing diffusion of an alkaline environment in which the chemical forming the material is disposed so as to surround the improved soil, wherein the water blocking wall is constructed so as to reach the impermeable layer, and is surrounded by the water blocking wall. The improved soil is buried therein, and a surface layer containing the drug is applied thereon.
[0011]
In the alkaline environment diffusion prevention method according to the present invention, the chemical is a phosphoric acid or sulfuric acid chemical fertilizer.
In the alkaline environment diffusion prevention method according to the present invention, the chemical is lime perphosphate, lime heavy perphosphate, or magnesium sulfate.
Further, the alkaline environment diffusion prevention method according to the present invention is used by mixing the chemical with normal soil.
Further, the alkaline environment diffusion preventing method according to the present invention, as described in claim 7, is a hardly soluble salt by reacting with calcium hydroxide contained in the improved soil treated with a cement-based material or a lime-based material. Is a method for preventing the diffusion of an alkaline environment by surrounding the improved soil so as to surround the improved soil, wherein the agent is mixed with normal soil.
[0012]
In the method for preventing diffusion of an alkaline environment according to the present invention, a chemical that forms a sparingly soluble salt by reacting with calcium hydroxide contained in an improved soil treated with a cement-based material or a lime-based material is added to the improved soil. Arrange to surround.
[0013]
In this way, the placed chemical reacts with calcium hydroxide, which is an alkali component that has been leached out from the improved soil, to form a hardly soluble salt, so that the calcium hydroxide is in the form of hydroxide ions. It does not spread. In other words, the placed drug functions as a diffusion preventing layer that prevents calcium hydroxide in the improved soil from diffusing around.
[0014]
The surrounding in the present invention includes a partial surrounding by a combination with a water blocking wall or an impermeable layer.
[0015]
When placing the chemical, the placement time of the improved soil in the form of embankment, etc. and then spraying on it, laying in advance before installing the improved soil, or in the buried area and waste disposal site A method of laying in advance on the inner surface of the disposal area is conceivable.
[0016]
In addition, the chemical may be used as it is as an arrangement method. However, if it is used in a state mixed with ordinary soil such as Masa soil or sandy soil, the alkali content will be reduced even for soil that does not have alkali neutralizing ability. It is possible to provide a function for preventing the diffusion of the above.
[0017]
The agent may be any agent that reacts with calcium hydroxide contained in the improved soil to form a poorly soluble salt, but if the agent is a phosphoric acid or sulfuric acid chemical fertilizer, Relatively easy to obtain, highly safe, and less affected by overspraying.
[0018]
In particular, if the agent is lime superphosphate, lime heavy superphosphate or magnesium sulfate, the pH can be lowered to about 10 without significantly increasing the electrical conductivity (EC), which is suitable for plant growth. Can create an environment.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an alkaline environment diffusion prevention method according to the present invention will be described below with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.
[0020]
FIG. 1 is a schematic diagram illustrating a method for preventing diffusion of an alkaline environment according to the present embodiment. As shown in the figure, in the alkaline environment diffusion prevention method according to this embodiment, as shown in the figure, first, as shown in FIG. The lime perphosphate, the lime heavy perphosphate, or the magnesium sulfate 2 as a sulfuric chemical fertilizer is laid beforehand.
[0021]
Next, the improved soil 3 treated with a cement-based material or a lime-based material is put into a buried region where the inner surface is laid with lime superphosphate or the like. Next, phosphoperphosphate, heavy perphosphate lime, or magnesium sulfate 4 as a phosphoric acid or sulfuric acid chemical fertilizer similar to that described above is sprayed on the improved soil 3.
[0022]
If it does in this way, the improvement soil 3 will become the shape surrounded by the superphosphate lime, the heavy superphosphate lime, or the magnesium sulfates 2 and 4, and this superphosphate lime etc. are the alkaline components which leached out from the inside of the improvement soil 3. It reacts with calcium hydroxide to form a sparingly soluble salt, and its fluidity is lowered to stay at the reaction site.
[0023]
That is, the superphosphate lime, the heavy superphosphate lime, or the magnesium sulfates 2 and 4 function as a diffusion preventing layer for preventing the calcium hydroxide in the improved soil 3 from diffusing around.
[0024]
As described above, according to the alkaline environment diffusion prevention method according to the present embodiment, even if calcium hydroxide contained in the improved soil 3 leaches out to the surroundings, the excessively disposed so as to surround it. Calcium hydroxide does not diffuse around in the form of hydroxide ions because it reacts with agents such as lime phosphate, lime heavy superphosphate or magnesium sulfate 2, 4 to form sparingly soluble salts. Moreover, since it becomes a hardly soluble salt, fluidity | liquidity falls and possibility that it will remain in this reaction position becomes high, and also spread | diffuses calcium hydroxide physically. Therefore, it is possible to maintain the environment around the improved soil 3 in an environment suitable for greening.
[0025]
Moreover, according to this embodiment, since the phosphoric acid type or sulfuric acid type chemical fertilizer was used as a chemical | medical agent, while obtaining easily, the special qualification is not required for the worker who sprays. Moreover, the safety at the time of spraying is high, and the adverse effects of excessive spraying are small.
[0026]
In addition, according to the present embodiment, since such a chemical fertilizer is used especially lime superphosphate, lime heavy perphosphate or magnesium sulfate, as will be described later, without increasing the electrical conductivity EC so much, The pH can be lowered to about 10, and an environment for growing most plants can be created around the improved soil.
[0027]
FIG. 2 is a graph showing the results of an experiment confirming the effects of the alkaline environment diffusion prevention method according to the present embodiment. The experiment shown in the graph is the result of investigating the decrease in pH by adding lime superphosphate, lime heavy superphosphate, magnesium sulfate and potassium sulfate bitter soil to the improved soil. It can be seen that the pH is lowered to about 10 by adding about 2 to 5% by weight of the above-mentioned three drugs excluding.
[0028]
Further, the experiment shown in the graph (b) is a result of examining the increase state of the electrical conductivity EC for the same case. From the graph, the electrical conductivity EC is 2 ms / cm under the above-described addition amount. It is considered that it only rises to a degree and has little effect on plant growth.
[0029]
As a cause of the results obtained from these graphs, in the case of superphosphate or heavy superphosphate, the phosphoric acid component and calcium hydroxide contained therein are H 3 PO 4 + Ca (OH) 2 → CaHPO. 4 + 2H 2 O
Or 2H 3 PO 4 + 3Ca (OH) 2 → Ca 3 (PO 4 ) 2 + 6H 2 O
It is expected that the pH of the calcium hydroxide is lowered due to the reaction in the form of calcium hydroxide being changed into poorly soluble CaHPO 4 or Ca 3 (PO 4 ) 2 and water.
[0030]
In the case of magnesium sulfate,
MgSO 4 + Ca (OH) 2 → Mg (OH) 2 + CaSO 4
It is expected that the pH is lowered because the hydroxide ions are taken into Mg (OH) 2 which is hardly soluble.
[0031]
Table 1 is the table | surface which showed the experimental result which confirmed the effect in the diffusion prevention method of the alkaline environment which concerns on this embodiment about the actual plant.
[0032]
[Table 1]
Figure 0004235772
The experiment shown in the table shows the growth of Komatsuna by changing the amount of addition for each of the total 5 cases with the addition of no chemical, lime superphosphate, lime heavy superphosphate, magnesium sulfate and potassium sulfate. From the same table, it can be seen from the same table that the improved soil added with superphosphate, heavy superphosphate and magnesium sulfate has a clear improvement effect on the growth of Komatsuna. In this experiment, the moisture of the improved soil was saturated so that the alkaline component in the improved soil would most affect the growth of the plant.
[0033]
Although this embodiment demonstrated the example which applied this invention about the improvement soil 3 used for a landfill material, this invention is not limited about the use of an improvement soil, A bank, a bank body other than a landfill material It can also be used for materials. Fig. 3 (a) shows that after laying preliminary lime, heavy perphosphate lime or magnesium sulfate 2 as a phosphate or sulfate chemical fertilizer on the ground 1 and embanking the improved soil 3 on it, the same applies. The example which sprayed the superphosphate lime, the heavy superphosphate lime, or the magnesium sulfate 4 was shown.
[0034]
Even in such a configuration, the improved soil 3 is surrounded by superphosphate, heavy superphosphate, or magnesium sulfates 2 and 4, and thus has substantially the same effect as described above although detailed description is omitted.
[0035]
Further, as shown in FIG. 2B, the water blocking wall 12 is constructed so as to reach the impermeable layer 11, and the improved soil 3 is embedded in the area surrounded by the water blocking wall 12. And the surface layer 5 containing a lime superphosphate, a heavy superphosphate lime, magnesium sulfate, etc. is constructed on it.
[0036]
Even in such a configuration, the improved soil 3 has a water-impermeable layer on its side and is surrounded by a surface layer 5 containing lime perphosphate, heavy perphosphate lime, or magnesium sulfate 4 on the upper side. Similarly to the above, the alkali component leached from the improved soil 3 forms a hardly soluble salt in the surface layer 5, and there is no possibility of leaching to the ground surface as hydroxide ions.
[0037]
Therefore, the vicinity of the ground surface can be maintained at an appropriate pH without being affected by the alkali content of the improved soil 3, and desired greening can be performed.
[0038]
Although not particularly mentioned in the above-described embodiment and each modified example, as a method for using the chemical, other than using lime perphosphate, heavy perphosphate lime, magnesium sulfate, or the like as it is by a method such as spraying, masa soil Or it may be used by mixing with normal soil such as sandy soil.
[0039]
According to such a configuration, it is possible to provide a function of preventing the alkali content from being diffused even in soil having no alkali neutralizing ability.
[0040]
【The invention's effect】
As described above, according to the alkaline environment diffusion prevention method of the present invention, even if calcium hydroxide contained in the improved soil leaches out, it reacts with a chemical disposed so as to surround it. Therefore, calcium hydroxide does not diffuse around as calcium hydroxide ions. Therefore, the environment around the improved soil can be maintained in an environment suitable for greening.
[0041]
In addition, according to the alkaline environment diffusion prevention method of the present invention according to claim 4, it is easy to obtain and no special qualification is required for the worker performing the spraying. In addition, there is an effect that the safety at the time of spraying is high and the adverse effect of excessive spraying is small.
[0042]
In addition, according to the alkaline environment diffusion prevention method of the present invention according to claim 5, it is possible to lower the pH to about 10 without increasing the electrical conductivity EC so much, and an environment in which most plants are grown. There is also an effect that it can be created.
[0043]
Moreover, according to the alkaline environment diffusion preventing method of the present invention according to claims 6 and 7, there is also an effect that it becomes possible to have a function of preventing the diffusion of the alkali content even for the soil having no alkali neutralizing ability. .
[0044]
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an alkaline environment diffusion prevention method according to an embodiment of the present invention.
FIG. 2 is a graph showing the action of the alkaline environment diffusion prevention method according to the present embodiment.
FIG. 3 is a schematic diagram of an alkaline environment diffusion prevention method according to a modification.
[Explanation of symbols]
3 improved soil 2, 4 superphosphate lime, heavy superphosphate lime or magnesium sulfate (phosphate or sulfate chemical fertilizer, chemical)
5 Surface layer containing superphosphate lime, etc.

Claims (7)

セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置するアルカリ環境の拡散防止方法であって、地盤を掘削して形成された埋設領域の内面に前記薬剤を予め敷設し、次いで、該薬剤で内面が敷設された前記埋設領域内に前記改良土を投入し、次いで、前記改良土の上に前記薬剤を散布することを特徴とするアルカリ環境の拡散防止方法。  A method for preventing diffusion of an alkaline environment in which an agent that forms a sparingly soluble salt by reacting with calcium hydroxide contained in an improved soil treated with a cement-based material or a lime-based material is disposed so as to surround the improved soil. The chemical is preliminarily laid on the inner surface of the buried area formed by excavating the ground, and then the improved soil is injected into the buried area where the inner surface is laid with the chemical, and then the improved A method for preventing the diffusion of an alkaline environment, the method comprising spraying the agent on soil. セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置するアルカリ環境の拡散防止方法であって、地盤の上に前記薬剤を予め敷設し、その上に前記改良土を盛土した後、前記薬剤を散布することを特徴とするアルカリ環境の拡散防止方法。  A method for preventing diffusion of an alkaline environment in which an agent that forms a sparingly soluble salt by reacting with calcium hydroxide contained in an improved soil treated with a cement-based material or a lime-based material is disposed so as to surround the improved soil. A method for preventing the diffusion of an alkaline environment, wherein the agent is preliminarily laid on the ground, and the improved soil is embanked thereon, and then the agent is sprayed. セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置するアルカリ環境の拡散防止方法であって、止水壁を不透水層に到達させる形で施工し、前記止水壁で囲まれた領域内に前記改良土を埋設し、その上に前記薬剤を含む表層を施工することを特徴とするアルカリ環境の拡散防止方法。  A method for preventing diffusion of an alkaline environment in which an agent that forms a sparingly soluble salt by reacting with calcium hydroxide contained in an improved soil treated with a cement-based material or a lime-based material is disposed so as to surround the improved soil. The construction is such that the water blocking wall is made to reach the impermeable layer, the improved soil is embedded in the area surrounded by the water blocking wall, and the surface layer containing the drug is applied thereon. A feature of preventing diffusion of an alkaline environment. 前記薬剤を燐酸系若しくは硫酸系化学肥料とする請求項１乃至請求項３のいずれか一記載のアルカリ環境の拡散防止方法。  The method for preventing diffusion of an alkaline environment according to any one of claims 1 to 3, wherein the chemical is a phosphoric acid or sulfuric acid chemical fertilizer. 前記薬剤を過燐酸石灰、重過燐酸石灰若しくは硫酸マグネシウムとする請求項４記載のアルカリ環境の拡散防止方法。  The method for preventing diffusion of an alkaline environment according to claim 4, wherein the chemical is lime superphosphate, lime heavy perphosphate, or magnesium sulfate. 前記薬剤を通常の土に混ぜて使用する請求項１乃至請求項５のいずれか一記載のアルカリ環境の拡散防止方法。  The method for preventing diffusion of an alkaline environment according to any one of claims 1 to 5, wherein the agent is used by mixing with ordinary soil. セメント系材料もしくは石灰系材料で処理された改良土に含まれる水酸化カルシウムと反応することによって難溶性の塩を形成する薬剤を前記改良土を包囲するようにして配置するアルカリ環境の拡散防止方法であって、前記薬剤を通常の土に混ぜて使用することを特徴とするアルカリ環境の拡散防止方法。  A method for preventing diffusion of an alkaline environment in which an agent that forms a sparingly soluble salt by reacting with calcium hydroxide contained in an improved soil treated with a cement-based material or a lime-based material is disposed so as to surround the improved soil. A method for preventing the diffusion of an alkaline environment, wherein the agent is used by mixing it with ordinary soil.
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