JP3751085B2 - Soil stabilization method - Google Patents

Soil stabilization method Download PDF

Info

Publication number
JP3751085B2
JP3751085B2 JP25507196A JP25507196A JP3751085B2 JP 3751085 B2 JP3751085 B2 JP 3751085B2 JP 25507196 A JP25507196 A JP 25507196A JP 25507196 A JP25507196 A JP 25507196A JP 3751085 B2 JP3751085 B2 JP 3751085B2
Authority
JP
Japan
Prior art keywords
solution
soil
sodium phosphate
water
curing agent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP25507196A
Other languages
Japanese (ja)
Other versions
JPH10102059A (en
Inventor
幸広 與田
正 長瀬
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsui Chemicals Inc
Original Assignee
Mitsui Chemicals Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsui Chemicals Inc filed Critical Mitsui Chemicals Inc
Priority to JP25507196A priority Critical patent/JP3751085B2/en
Publication of JPH10102059A publication Critical patent/JPH10102059A/en
Application granted granted Critical
Publication of JP3751085B2 publication Critical patent/JP3751085B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
    • C04B28/26—Silicates of the alkali metals
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
    • C04B22/08—Acids or salts thereof
    • C04B22/16—Acids or salts thereof containing phosphorus in the anion, e.g. phosphates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
    • C04B2103/10—Accelerators; Activators
    • C04B2103/14—Hardening accelerators
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00732—Uses not provided for elsewhere in C04B2111/00 for soil stabilisation
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/70—Grouts, e.g. injection mixtures for cables for prestressed concrete

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Soil Conditioners And Soil-Stabilizing Materials (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、土壌の安定化方法に関し、さらに詳しくは軟弱地盤に水ガラス系グラウト薬剤を注入し地盤強化あるいは漏水地盤の止水を行う土壌安定化方法に関する。
【０００２】
【従来の技術】
従来、軟弱地盤の強化や漏水地盤を止水する目的で、種々の土壌改良剤を土壌中に注入し硬化させるグラウト工法が知られている。なかでも、水ガラスを主剤として硬化剤と組み合わせて使用する珪酸塩系グラウト工法は、安価であること、他の有機系土壌改良剤（アクリルアマイド，尿素樹脂，ウレタン，リグニン系等）に比べ動植物等に害を起こす危険性が殆どなく、環境を汚染しないこと等の為広く実用化されている。
【０００３】
軟弱地盤の安定化方法としては、従来種々の工法が用いられている。例えば、水ガラス水溶液（Ａ液）と硬化剤水溶液（Ｂ液）を混和装置により１液として１台のポンプで注入する１ショット法や、Ａ，Ｂ両液をそれぞれ独立した注入ポンプで圧送し、Ｙ字管で合流混合して１液となし注入する１．５ショット法がある。また、Ａ，Ｂ両液をそれぞれ注入管の先端部で合流して圧入する２ショット法も広く用いられている。
【０００４】
これらの工法に用いられる硬化剤としては、水ガラス水溶液に酸を加えると容易に反応して珪酸含水ゲルを形成し硬化することを利用し、酸性塩類（重炭酸ナトリウム，重炭酸カリウム，重硫酸ナトリウム等），鉱酸類（硫酸，燐酸等）及び有機酸等種々の酸性反応剤が提案されている。
【０００５】
グラウト施工時には、これらの硬化剤を攪拌機装備の溶解槽を用い所定の濃度となるように水に溶解して硬化剤水溶液（Ｂ液）として用いられる。中でも酸性塩類を用いた硬化剤は安全性も高くグラウト性能も比較的良好なことから多用されている。しかし、これらの酸性塩類は多くが粉末状であるため、溶解作業が煩雑となり、作業の自動化が難しいといった問題が指摘されている。なお、硬化剤によっては水に対する溶解度が充分ではなく、特に冬期において溶解不良の問題が発生することもしばしばである。また、粉体に特有の固結の問題も重大であり、保管上の難点とされている。
【０００６】
一方、硫酸や燐酸等の鉱酸類は液体状であることから上記の問題は解決され作業性の良い硬化剤と考えられる。しかし、鉱酸類を硬化剤とする場合ゲル化時間のバラツキが大きく、とりわけ数分〜数十分の範囲で安定したゲルタイムを有する処方を得ることは非常に難しい。すなわち、ゲル化は水ガラスと硬化剤の中和反応を基本としており、僅かな配合の変化でゲル化時間が大きく変動するため安定したゲル化時間が得られない。また、主剤である水ガラス組成のバラツキや、液温の影響も大きく、施工時のトラブルの原因となることがある。
【０００７】
更には、グラウト薬液が土壌中に注入される際、土壌中の水により希釈される可能性もあるが、その際の水希釈によるゲルタイム遅延の問題も大きな課題となっている。
【０００８】
【発明が解決しようとする課題】
そこで本発明の目的は、水ガラス系グラウト工法による土壌安定化方法において、従来の技術で挙げられる上記のごとき問題点を解決し、グラウト薬剤として取り扱いが容易な硬化剤、安定化したゲル化時間及びゲルの高強度化等の要求に答えられる方法を見いだすことにある。
【０００９】
【課題を解決するための手段】
本発明者らは、かかる実情に鑑み、グラウト薬剤として取り扱いが容易な液状硬化剤を使用することを前提とし、安定化したゲル化時間と高強度のゲルを目的として鋭意検討を重ねた結果、以下の方法を見い出し本発明を完成するに至った。
【００１０】
すなわち、本発明は、
（１） 主剤と硬化剤とからなる水ガラス系グラウト薬剤を土壌中に注入してゲル化させ、該土壌を固化し安定化を図る土壌安定化方法であって、硬化剤としてＰ2Ｏ5濃度が３０〜５０重量％であり、Ｎａ／Ｐモル比が０．２〜０．６である燐酸ナトリウム水溶液を使用することを特徴とする土壌安定化方法、
（２） 燐酸ナトリウム水溶液が、硫酸マグネシウムを含有することを特徴とする（１）記載の土壌安定化方法、
（３） 燐酸ナトリウム水溶液中に含有される硫酸マグネシウムが、ＳＯ3として１．５〜４．５重量％及びＭｇＯとして０．３〜２．５重量％であることを特徴とする（２）記載の土壌安定化方法、
を提供するものである。
【００１１】
【発明の実施の形態】
以下、本発明を更に詳細に説明する。
本発明の水ガラス系グラウト薬剤において主剤となる水ガラスについては特に制限はないが、ＪＩＳに規定される３号及び２号珪酸ソ−ダが入手が容易で好適である。
【００１２】
水ガラス水溶液（Ａ液）中の珪酸ソ−ダ濃度はグラウト施工上重要な因子であり、土壌の性状，設定ゲル化時間及びゲル強度等を考慮して決定される。通常、珪酸ソ−ダを１０〜４０重量％程度含有する水ガラス水溶液が使用される。
【００１３】
本発明において硬化剤として使用される燐酸ナトリウム水溶液とは、Ｐ2Ｏ5濃度が３０〜５０重量％であり、Ｎａ／Ｐモル比が０．２〜０．６である燐酸ナトリウム水溶液のことである。
該水溶液は、原料である燐酸に所定量のナトリウム化合物及び水を添加し濃度を調整することにより得られる。
【００１４】
上記の原料の燐酸としては特に制限はなく、一般に工業原料として市販されているものを用いることができる。すなわち、燐酸の製造方法としては、湿式法，乾式法が代表的であるが、いずれの燐酸も使用可能である。特に、湿式法による工業用燐酸からフッ素及び塩素分を除去した燐酸は、有害性が少なく装置材料に対する腐食性も低減されていることから好適である。
【００１５】
また、燐酸からこのフッ素及び塩素分の効率的な除去法に関しては、スチ−ムストリッピングによる方法（特開平７−２５７９１４）が提案されているが、本発明はその除去法等に制限されるものではない。
本発明の燐酸に添加するナトリウム化合物についても特に制限はなく、市販されている苛性ソ−ダ及び炭酸ソ−ダが安価であり最も適している。
【００１６】
本発明の硬化剤である燐酸ナトリウム水溶液のＰ2Ｏ5濃度は、３０〜５０重量％、好ましくは３５〜４５重量％である。該水溶液中のＰ2Ｏ5濃度が３０重量％未満では、あまりにも希薄であり運搬，貯蔵等のコストが高くなり実用上経済的ではない。また、５０重量％を超えると、低温下において燐酸ナトリウムの結晶が析出しやすく不安定であることから好ましくない。
【００１７】
本発明における燐酸ナトリウム水溶液のＮａ／Ｐモル比は、０．２〜０．６である。モル比が０．２未満ではナトリウムの添加効果が小さく不十分である。モル比が０．６を超えると、グラウト性能の向上もさほど望めないばかりか、硬化剤使用量が増加することから経済的ではなくなる。また、低温下において燐酸ナトリウム結晶の析出や粘度上昇による作業性低下等のトラブルも予想されるので好ましくない。
更に、本発明において燐酸ナトリウム水溶液が硫酸マグネシウムを含有する場合には、固結強度がさらに大きくなり、不透水性に優れたゲルの生成が可能となる。
【００１８】
燐酸ナトリウム水溶液中の硫酸マグネシウム含有量については特に制限はないが、燐酸への溶解度の関係から、ＳＯ3として１．５〜４．５重量％及びＭｇＯとして０．３〜２．５重量％程度が好ましい。
【００１９】
硫酸マグネシウム含有燐酸ナトリウム水溶液の製造方法についても、特に制限はなく、燐酸水溶液中へ硫酸マグネシウム（ＭｇＳＯ4・７Ｈ2Ｏ）を添加溶解することで容易に製造できる。あるいは、硫酸（Ｈ2ＳＯ4）とマグネシウム化合物（酸化マグネシウム，水酸化マグネシウムまたは炭酸マグネシウム）をそれぞれ所定量添加溶解することでも得ることができる。
【００２０】
硬化剤水溶液（Ｂ液）中の硬化剤濃度については特に制限はなく、通常Ｐ2Ｏ5として１〜５重量％程度である。いずれにせよ施工に当たっては、対象地盤の土質調査を行い、最適ゲルタイムを決定した上で薬液の配合を決めるのが望ましい。
【００２１】
本発明の施工方法については特に制限はなく、一般的に行われている方法が採用できる。すなわち、前述した１、１．５及び２ショット法のいずれの工法も使用可能である。
【００２２】
硬化剤中に添加したナトリウムや硫酸マグネシウム成分の作用機構については明らかではないが、ゲル生成過程における珪酸コロイド粒子の凝集を助けたり、ゲル骨格に入ることによる強度向上への寄与等が考えられる。
【００２３】
本発明によれば、低温下においても安定な液状硬化剤を使用することにより、施工上の管理，操作が極めて容易であるばかりか、ゲルタイムの安定、硬度も改善されより効果的な土壌安定化が可能となる。
【００２４】
【実施例】
以下、実施例により本発明を具体的に説明する。なお、製造例，実施例，比較例中の％およびｐｐｍはそれぞれ重量％，重量ｐｐｍを示す。
【００２５】
製造例１
燐鉱石（ファラボア鉱：南ア共和国産）を硫酸で分解し、Ｐ2Ｏ5＝５６％，Ｃｌ＝５０ｐｐｍ，Ｆ＝２，０００ｐｐｍの燐酸液を調合した。この燐酸液１，０００ｍｌを外部加熱装置装備通気攪拌槽（内容量２ｌ）に移し、１５０℃に加熱した。次に、槽下部に設けられたスパ−ジャ−より１５０℃のスチ−ムを４００ｇ／ｈで８時間吹き込むことでスチ−ムストリッピング処理を行った。得られた燐酸液を分析したところ、Ｐ2Ｏ5＝５４．５％，Ｃｌ＜５ｐｐｍ，Ｆ＜５ｐｐｍであり、原料燐酸で感じられた刺激臭が消失しており無臭であった。
【００２６】
この燐酸液に、所定量の４８％苛性ソ−ダ水溶液及び水を加え、Ｐ2Ｏ5＝４０％，Ｎａ／Ｐモル比＝０．３である燐酸ナトリウム水溶液を製造した。
得られた燐酸液は粘性も低く（３０ｃｐｓ／１０℃）、液体としての取り扱い上問題がないことを確認した。
更に、上記燐酸ナトリウム水溶液の貯蔵安定性を確認するため、０℃雰囲気下，９０日間保存試験を行った。その結果、燐酸ナトリウム等の結晶析出は認められず低温下においても安定であることが確認された。
【００２７】
製造例２
製造例１と同様の方法で得たスチ−ムストリッピング処理済み燐酸液に、所定量の４８％苛性ソ−ダ水溶液，９８％硫酸，酸化マグネシウム（ＭｇＯ）及び水を添加溶解し、Ｐ2Ｏ5＝４０％，Ｎａ／Ｐモル比＝０．３，ＳＯ3＝２．０％，ＭｇＯ＝０．７％である燐酸ナトリウム水溶液を製造した。
得られた燐酸液は製造例１と同様に粘性は低く（３５ｃｐｓ／１０℃）、低温下における貯蔵安定性（０℃−９０日）も充分であることが分かった。
【００２８】
比較製造例１
製造例１と同様の方法で得たスチ−ムストリッピング処理済み燐酸液に、所定量の４８％苛性ソ−ダ水溶液及び水を加え、Ｐ2Ｏ5＝４０％，Ｎａ／Ｐモル比＝０．８である燐酸ナトリウム水溶液を製造した。
得られた燐酸ナトリウム水溶液の貯蔵安定性を確認するため、５℃雰囲気下において保存試験を行った。その結果、３日後には燐酸ナトリウムと思われる結晶の析出が認められ硬化剤として実用上問題となることが判明した。
【００２９】
比較製造例２
市販の精製燐酸（Ｐ2Ｏ5＝６１．６％）に所定量の炭酸ソ−ダを溶解し、Ｐ2Ｏ5＝５４．３％，Ｎａ／Ｐモル比＝０．５である燐酸ナトリウム水溶液を製造した。
得られた燐酸ナトリウム水溶液の貯蔵安定性を確認するため、５℃雰囲気下において保存試験を行った。その結果、１日後には燐酸ナトリウムと思われる結晶の析出が認められたので、硬化剤として実用上問題となることが判明した。
【００３０】
実施例１
珪酸ソ−ダ（ＪＩＳ−３号，比重＝１．４）１４０ｇに水１００ｇを加えＡ液とした。別に、製造例１の燐酸ナトリウム水溶液（比重＝１．４８）１５．２ｇを水１９０ｇで希釈して調製した硬化剤溶液をＢ液とした。
Ａ液とＢ液を混合し、２０℃におけるゲル化タイムを測定したところ３１分であった。
さらに、Ａ，Ｂ両液を混合したものを豊浦標準砂に浸透固結させて得たサンドゲルの一軸圧縮強度を土質試験法ＪＩＳＡ−１２１６に準じた方法でゲル化５日後に測定したところ、２．１Ｋｇｆ／ｃｍ2であった。
次に薬液の水希釈による影響を調べた。上記と同組成のＡ，Ｂ両液を混合したものに対し４０ｇの水を添加して２０℃におけるゲル化タイムを測定し、９３分の結果を得た。
【００３１】
実施例２
珪酸ソ−ダ（ＪＩＳ−３号，比重＝１．４）１４０ｇに水１００ｇを加えＡ液とした。別に、製造例２の燐酸ナトリウム水溶液（比重＝１．５２）１４．５ｇを水１９０ｇで希釈して調製した硬化剤溶液をＢ液とした。
Ａ液とＢ液を混合し、２０℃におけるゲル化タイムを測定したところ３４分であった。
さらに、Ａ，Ｂ両液を混合したものを豊浦標準砂に浸透固結させて得たサンドゲルの一軸圧縮強度を土質試験法ＪＩＳＡ−１２１６に準じた方法でゲル化５日後に測定したところ、２．５Ｋｇｆ／ｃｍ2であった。
次に薬液の水希釈による影響を調べた。上記と同組成のＡ，Ｂ両液を混合したものに対し４０ｇの水を添加して２０℃におけるゲル化タイムを測定し、８８分の結果を得た。
【００３２】
比較例１
珪酸ソ−ダ（ＪＩＳ−３号，比重＝１．４）１４０ｇに水１００ｇを加えＡ液とした。別に、市販の精製燐酸（Ｐ2Ｏ5＝５４．５％，比重＝１．５８）１０．４ｇを水１９３ｇで希釈して調製した硬化剤溶液をＢ液とした。
Ａ液とＢ液を混合し、２０℃におけるゲル化タイムを測定したところ３２分であった。
さらに、Ａ，Ｂ両液を混合したものを豊浦標準砂に浸透固結させて得たサンドゲルの一軸圧縮強度を土質試験法ＪＩＳＡ−１２１６に準じた方法でゲル化５日後に測定したところ、１．７Ｋｇｆ／ｃｍ2であった。
次に薬液の水希釈による影響を調べた。上記と同組成のＡ，Ｂ両液を混合したものに対し４０ｇの水を添加して２０℃におけるゲル化タイムを測定し、１４５分の結果を得た。
これは、当初の狙いである８５〜９５分のゲルタイムから大きく遅れることになり、この結果実際の現場施工時には大きな問題となることが判明した。
【００３３】
実施例３
珪酸ソ−ダ（ＪＩＳ−３号，比重＝１．４）１１２ｇに水１２０ｇを加えＡ液とした。別に、硬化剤としてＰ2Ｏ5＝４５％，Ｎａ／Ｐモル比＝０．４，ＳＯ3＝３．６％，ＭｇＯ＝１．８％に調整した燐酸ナトリウム水溶液１１．７ｇを水１９３ｇで希釈して調製した硬化剤溶液をＢ液とした。
実施例１と同様、２０℃におけるゲル化タイム及びサンドゲルの一軸圧縮強度を測定したところそれぞれ、３０分及び２．１Ｋｇｆ／ｃｍ2であった。
次に薬液の水希釈による影響を調べた。上記と同組成のＡ，Ｂ両液を混合したものに対し４０ｇの水を添加して２０℃におけるゲル化タイムを測定し、８５分の結果を得た。
【００３４】
【発明の効果】
以上述べたように、本発明は水ガラス系グラウト工法において、硬化剤として安定な燐酸ナトリウム水溶液を使用するものである。硬化剤が液状であることから、粉体物質にありがちな固結や溶解不良もなく、施工上取り扱いが極めて容易であるばかりか、グラウト薬剤としてもゲルタイム安定性，ゲル強度等の点で優れた性能を発揮する。
【００３５】
また、本発明において使用する硬化剤は、冬場での現場施工上の問題となる低温下での貯蔵安定性に優れており、さらに本発明で使用するグラウト薬剤は、土壌中に注入される際に土壌中の水により希釈された場合でも、施工前に設定したゲルタイムが変化しない為、水希釈によるゲルタイム遅延の問題も発生せず、極めて取扱いが容易である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a soil stabilization method, and more particularly, to a soil stabilization method for injecting a water glass grout agent into soft ground to strengthen the ground or stop water leakage.
[0002]
[Prior art]
Conventionally, a grout method is known in which various soil conditioners are injected into the soil and hardened for the purpose of strengthening the soft ground or stopping the leaked ground. Above all, the silicate grout method, which uses water glass as the main ingredient in combination with the hardener, is inexpensive, and animals and plants compared to other organic soil improvers (acrylic amide, urea resin, urethane, lignin, etc.). There is almost no risk of causing harm to the environment, and it is widely put into practical use because it does not pollute the environment.
[0003]
Conventionally, various methods are used as a method for stabilizing soft ground. For example, a one-shot method in which a water glass aqueous solution (liquid A) and an aqueous hardener solution (liquid B) are injected as a single liquid by a mixing device with a single pump, or both liquids A and B are pumped by independent injection pumps There is a 1.5 shot method in which a Y-tube is mixed and mixed to form one liquid. A two-shot method is also widely used in which both A and B liquids are joined together at the tip of the injection tube and press-fitted.
[0004]
Curing agents used in these methods include the use of acid salts (sodium bicarbonate, potassium bicarbonate, bisulfuric acid) by utilizing the fact that an acid is added to a water glass aqueous solution to react easily to form a silicic acid hydrogel. Various acidic reactants such as sodium), mineral acids (sulfuric acid, phosphoric acid, etc.) and organic acids have been proposed.
[0005]
At the time of grout construction, these curing agents are dissolved in water so as to have a predetermined concentration using a dissolution tank equipped with a stirrer and used as an aqueous curing agent solution (B liquid). Among them, curing agents using acidic salts are frequently used because of their high safety and relatively good grout performance. However, since many of these acidic salts are in powder form, it has been pointed out that the dissolution work becomes complicated and it is difficult to automate the work. Depending on the curing agent, the solubility in water is not sufficient, and the problem of poor dissolution often occurs especially in winter. In addition, the problem of consolidation specific to powder is also a serious problem, which is a difficult point in storage.
[0006]
On the other hand, since mineral acids such as sulfuric acid and phosphoric acid are in a liquid state, the above problems are solved and it is considered that the curing agent has good workability. However, when mineral acids are used as curing agents, the variation in gelation time is large, and it is very difficult to obtain a formulation having a stable gel time in the range of several minutes to several tens of minutes. That is, gelation is based on a neutralization reaction between water glass and a curing agent, and the gelation time varies greatly due to a slight change in the composition, so a stable gelation time cannot be obtained. Moreover, the variation of the water glass composition which is the main agent and the influence of the liquid temperature are large, which may cause troubles during construction.
[0007]
Furthermore, when grout chemical | medical solution is inject | poured in soil, it may be diluted with the water in soil, but the problem of the gel time delay by the water dilution in that case is also a big subject.
[0008]
[Problems to be solved by the invention]
Therefore, the object of the present invention is to solve the above-mentioned problems mentioned in the prior art in a soil stabilization method by a water glass grout method, a curing agent that is easy to handle as a grout agent, and a stabilized gelation time. It is also to find a method that can respond to the demand for increasing the strength of the gel.
[0009]
[Means for Solving the Problems]
In view of such circumstances, the present inventors, on the premise of using a liquid curing agent that is easy to handle as a grout drug, as a result of intensive studies for the purpose of stabilizing gelation time and high-strength gel, The present inventors have found the following method and completed the present invention.
[0010]
That is, the present invention
(1) A soil stabilization method in which a water glass grout agent composed of a main agent and a curing agent is injected into a soil to cause gelation, and the soil is solidified and stabilized, and P 2 O 5 is used as a curing agent. A soil stabilization method characterized by using a sodium phosphate aqueous solution having a concentration of 30 to 50% by weight and a Na / P molar ratio of 0.2 to 0.6,
(2) The soil stabilization method according to (1), wherein the sodium phosphate aqueous solution contains magnesium sulfate,
(3) The magnesium sulfate contained in the sodium phosphate aqueous solution is 1.5 to 4.5% by weight as SO 3 and 0.3 to 2.5% by weight as MgO. Soil stabilization method,
Is to provide.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
Although there is no restriction | limiting in particular about the water glass used as the main ingredient in the water glass grout chemical | medical agent of this invention, No. 3 and No. 2 silicate soda prescribed | regulated by JIS are easy to obtain and suitable.
[0012]
Silica soda concentration in the water glass aqueous solution (A solution) is an important factor in the construction of the grout, and is determined in consideration of the properties of the soil, the set gel time, the gel strength, and the like. Usually, a water glass aqueous solution containing about 10 to 40% by weight of silicate soda is used.
[0013]
The sodium phosphate aqueous solution used as a curing agent in the present invention is a sodium phosphate aqueous solution having a P 2 O 5 concentration of 30 to 50% by weight and a Na / P molar ratio of 0.2 to 0.6. is there.
The aqueous solution can be obtained by adding a predetermined amount of a sodium compound and water to phosphoric acid as a raw material and adjusting the concentration.
[0014]
There is no restriction | limiting in particular as phosphoric acid of said raw material, What is generally marketed as an industrial raw material can be used. That is, as a method for producing phosphoric acid, a wet method and a dry method are typical, but any phosphoric acid can be used. In particular, phosphoric acid obtained by removing fluorine and chlorine from industrial phosphoric acid by a wet method is preferable because it is less harmful and less corrosive to equipment materials.
[0015]
As an efficient method for removing fluorine and chlorine from phosphoric acid, a steam stripping method (Japanese Patent Laid-Open No. 7-257914) has been proposed, but the present invention is limited to the removal method and the like. is not.
The sodium compound added to the phosphoric acid of the present invention is not particularly limited, and commercially available caustic soda and carbonated soda are inexpensive and most suitable.
[0016]
The concentration of P 2 O 5 in the aqueous sodium phosphate solution as the curing agent of the present invention is 30 to 50% by weight, preferably 35 to 45% by weight. If the concentration of P 2 O 5 in the aqueous solution is less than 30% by weight, it is too dilute and the costs for transportation, storage, etc. are high, and it is not practically economical. On the other hand, if it exceeds 50% by weight, it is not preferable because crystals of sodium phosphate are likely to precipitate at low temperatures and are unstable.
[0017]
The Na / P molar ratio of the sodium phosphate aqueous solution in the present invention is 0.2 to 0.6. If the molar ratio is less than 0.2, the effect of adding sodium is small and insufficient. When the molar ratio exceeds 0.6, the improvement of grout performance cannot be expected so much, and the amount of the curing agent used increases, so that it is not economical. In addition, troubles such as precipitation of sodium phosphate crystals and a decrease in workability due to an increase in viscosity are expected at low temperatures, which is not preferable.
Further, in the present invention, when the sodium phosphate aqueous solution contains magnesium sulfate, the consolidation strength is further increased, and a gel having excellent water impermeability can be produced.
[0018]
No particular limitation is imposed on magnesium sulfate content in sodium phosphate aqueous solution, about 0.3 to 2.5% by weight solubility in relation to the phosphate, as SO 3 as 1.5 to 4.5 wt% and MgO Is preferred.
[0019]
For the manufacturing method of the magnesium-containing phosphate sodium sulfate aqueous solution is not particularly limited, it can be easily produced by adding dissolving magnesium sulfate (MgSO 4 · 7H 2 O) to the aqueous solution of phosphoric acid in the. Alternatively, it can also be obtained by adding and dissolving a predetermined amount of sulfuric acid (H 2 SO 4 ) and a magnesium compound (magnesium oxide, magnesium hydroxide or magnesium carbonate).
[0020]
No particular limitation is imposed on the curing agent concentration in the curing agent solution (B solution) is about 1 to 5% by weight as a normal P 2 O 5. In any case, it is desirable to conduct a soil survey of the target ground, determine the optimum gel time, and then determine the chemical composition.
[0021]
There is no restriction | limiting in particular about the construction method of this invention, The method currently performed generally is employable. That is, any of the 1, 1.5 and 2-shot methods described above can be used.
[0022]
Although the mechanism of action of the sodium and magnesium sulfate components added to the curing agent is not clear, it may be possible to help the aggregation of silicic acid colloidal particles during the gel formation process or to contribute to strength improvement by entering the gel skeleton.
[0023]
According to the present invention, by using a liquid curing agent that is stable even at low temperatures, construction management and operation are extremely easy, as well as improved gel time stability and hardness, and more effective soil stabilization. Is possible.
[0024]
【Example】
Hereinafter, the present invention will be described specifically by way of examples. In the production examples, examples and comparative examples, “%” and “ppm” represent “% by weight” and “ppm by weight”, respectively.
[0025]
Production Example 1
Phosphorous ore (Faraboa ore: South Africa) was decomposed with sulfuric acid to prepare a phosphoric acid solution with P 2 O 5 = 56%, Cl = 50 ppm, F = 2,000 ppm. 1,000 ml of this phosphoric acid solution was transferred to an aeration and stirring tank equipped with an external heating device (internal volume 2 l) and heated to 150 ° C. Next, a steam stripping process was performed by blowing a steam at 150 ° C. at 400 g / h for 8 hours from a sparger provided at the bottom of the tank. The obtained phosphoric acid solution was analyzed. As a result, P 2 O 5 = 54.5%, Cl <5 ppm, F <5 ppm, the irritating odor felt with the raw material phosphoric acid disappeared and it was odorless.
[0026]
A predetermined amount of 48% aqueous sodium hydroxide solution and water were added to this phosphoric acid solution to produce a sodium phosphate aqueous solution with P 2 O 5 = 40% and Na / P molar ratio = 0.3.
The obtained phosphoric acid solution had low viscosity (30 cps / 10 ° C.), and it was confirmed that there was no problem in handling as a liquid.
Furthermore, in order to confirm the storage stability of the aqueous sodium phosphate solution, a storage test was conducted in an atmosphere of 0 ° C. for 90 days. As a result, no crystal precipitation such as sodium phosphate was observed, and it was confirmed that it was stable even at low temperatures.
[0027]
Production Example 2
A predetermined amount of 48% caustic soda aqueous solution, 98% sulfuric acid, magnesium oxide (MgO) and water are added to and dissolved in the phosphoric acid solution which has been subjected to the steam stripping treatment obtained in the same manner as in Production Example 1, and P 2 O An aqueous sodium phosphate solution having 5 = 40%, Na / P molar ratio = 0.3, SO 3 = 2.0%, and MgO = 0.7% was prepared.
It was found that the obtained phosphoric acid solution had a low viscosity (35 cps / 10 ° C.) as in Production Example 1 and sufficient storage stability at low temperatures (0 ° C.-90 days).
[0028]
Comparative production example 1
A predetermined amount of 48% caustic soda aqueous solution and water were added to the steam stripping-treated phosphoric acid solution obtained by the same method as in Production Example 1, and P 2 O 5 = 40%, Na / P molar ratio = 0. An aqueous sodium phosphate solution of .8 was prepared.
In order to confirm the storage stability of the obtained aqueous sodium phosphate solution, a storage test was conducted in an atmosphere at 5 ° C. As a result, it was found that after 3 days, precipitation of crystals considered to be sodium phosphate was observed, which became a practical problem as a curing agent.
[0029]
Comparative production example 2
Sodium phosphate in which a predetermined amount of soda is dissolved in commercially available purified phosphoric acid (P 2 O 5 = 61.6%), P 2 O 5 = 54.3%, Na / P molar ratio = 0.5 An aqueous solution was prepared.
In order to confirm the storage stability of the obtained aqueous sodium phosphate solution, a storage test was conducted in an atmosphere at 5 ° C. As a result, after one day, precipitation of crystals considered to be sodium phosphate was observed, which proved to be a practical problem as a curing agent.
[0030]
Example 1
100 g of water was added to 140 g of sodium silicate soda (JIS-3, specific gravity = 1.4) to prepare a solution A. Separately, a curing agent solution prepared by diluting 15.2 g of the sodium phosphate aqueous solution (specific gravity = 1.48) of Production Example 1 with 190 g of water was designated as solution B.
It was 31 minutes when A liquid and B liquid were mixed and the gelation time in 20 degreeC was measured.
Furthermore, when the uniaxial compressive strength of the sand gel obtained by infiltrating and consolidating the mixture of both A and B liquids in Toyoura standard sand was measured 5 days after gelation by a method according to the soil test method JISA-1216, 2 It was 1 kgf / cm 2 .
Next, the influence of the chemical solution diluted with water was examined. 40 g of water was added to a mixture of both A and B liquids having the same composition as above, and the gelation time at 20 ° C. was measured to obtain a result of 93 minutes.
[0031]
Example 2
100 g of water was added to 140 g of sodium silicate soda (JIS-3, specific gravity = 1.4) to prepare a solution A. Separately, a curing agent solution prepared by diluting 14.5 g of the sodium phosphate aqueous solution (specific gravity = 1.52) of Production Example 2 with 190 g of water was designated as solution B.
It was 34 minutes when A liquid and B liquid were mixed and the gelation time in 20 degreeC was measured.
Furthermore, when the uniaxial compressive strength of the sand gel obtained by infiltrating and consolidating the mixture of both A and B liquids in Toyoura standard sand was measured 5 days after gelation by a method according to the soil test method JISA-1216, 2 It was 5 kgf / cm 2 .
Next, the influence of the chemical solution diluted with water was examined. 40 g of water was added to a mixture of both A and B liquids having the same composition as above, and the gelation time at 20 ° C. was measured, and a result of 88 minutes was obtained.
[0032]
Comparative Example 1
100 g of water was added to 140 g of sodium silicate soda (JIS-3, specific gravity = 1.4) to prepare a solution A. Separately, a curing agent solution prepared by diluting 10.4 g of commercially available purified phosphoric acid (P 2 O 5 = 54.5%, specific gravity = 1.58) with 193 g of water was designated as solution B.
It was 32 minutes when A liquid and B liquid were mixed and the gelation time in 20 degreeC was measured.
Furthermore, when the uniaxial compressive strength of the sand gel obtained by infiltrating and consolidating the mixture of both A and B liquids in Toyoura standard sand was measured 5 days after gelation by a method according to the soil test method JISA-1216, 1 0.7 kgf / cm 2 .
Next, the influence of the chemical solution diluted with water was examined. 40 g of water was added to a mixture of the A and B liquids having the same composition as above, and the gelation time at 20 ° C. was measured to obtain a result of 145 minutes.
This was greatly delayed from the original target gel time of 85 to 95 minutes, and as a result, it was found that this would be a major problem during actual site construction.
[0033]
Example 3
120 g of water was added to 112 g of silicic acid soda (JIS-3, specific gravity = 1.4) to prepare a solution A. Separately, 11.7 g of an aqueous sodium phosphate solution adjusted to P 2 O 5 = 45%, Na / P molar ratio = 0.4, SO 3 = 3.6%, MgO = 1.8% as a curing agent was added with 193 g of water. The curing agent solution prepared by dilution was designated as B solution.
As in Example 1, the gelation time at 20 ° C. and the uniaxial compressive strength of the sand gel were measured and found to be 30 minutes and 2.1 kgf / cm 2 , respectively.
Next, the influence of the chemical solution diluted with water was examined. 40 g of water was added to a mixture of both A and B liquids having the same composition as above, and the gelation time at 20 ° C. was measured to obtain a result of 85 minutes.
[0034]
【The invention's effect】
As described above, the present invention uses a stable aqueous sodium phosphate solution as a curing agent in the water glass grout method. Since the hardener is in liquid form, there is no caking or poor dissolution that tends to occur in powder materials, it is extremely easy to handle in construction, and it is also excellent in terms of gel time stability and gel strength as a grout agent. Demonstrate performance.
[0035]
In addition, the curing agent used in the present invention is excellent in storage stability at low temperatures, which is a problem in field construction in winter, and the grout agent used in the present invention is injected into the soil. Even when diluted with water in the soil, the gel time set before construction does not change, so the problem of gel time delay due to water dilution does not occur, and it is extremely easy to handle.

Claims (3)

主剤と硬化剤とからなる水ガラス系グラウト薬剤を土壌中に注入してゲル化させ、該土壌を固化し安定化を図る土壌安定化方法であって、硬化剤としてＰ2Ｏ5濃度が３０〜５０重量％であり、Ｎａ／Ｐモル比が０．２〜０．６である燐酸ナトリウム水溶液を使用することを特徴とする土壌安定化方法。A soil stabilization method in which a water glass grout agent composed of a main agent and a curing agent is injected into the soil to cause gelation, and the soil is solidified and stabilized, with a P 2 O 5 concentration of 30 as the curing agent. A method for stabilizing a soil, characterized in that an aqueous sodium phosphate solution having a Na / P molar ratio of 0.2 to 0.6 is used. 燐酸ナトリウム水溶液が、硫酸マグネシウムを含有することを特徴とする請求項１記載の土壌安定化方法。The soil stabilization method according to claim 1, wherein the sodium phosphate aqueous solution contains magnesium sulfate. 燐酸ナトリウム水溶液中に含有される硫酸マグネシウムが、ＳＯ3として１．５〜４．５重量％及びＭｇＯとして０．３〜２．５重量％であることを特徴とする請求項２記載の土壌安定化方法。 3. The soil stability according to claim 2, wherein the magnesium sulfate contained in the aqueous sodium phosphate solution is 1.5 to 4.5 wt% as SO 3 and 0.3 to 2.5 wt% as MgO. Method.
JP25507196A 1996-09-26 1996-09-26 Soil stabilization method Expired - Fee Related JP3751085B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP25507196A JP3751085B2 (en) 1996-09-26 1996-09-26 Soil stabilization method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP25507196A JP3751085B2 (en) 1996-09-26 1996-09-26 Soil stabilization method

Publications (2)

Publication Number Publication Date
JPH10102059A JPH10102059A (en) 1998-04-21
JP3751085B2 true JP3751085B2 (en) 2006-03-01

Family

ID=17273738

Family Applications (1)

Application Number Title Priority Date Filing Date
JP25507196A Expired - Fee Related JP3751085B2 (en) 1996-09-26 1996-09-26 Soil stabilization method

Country Status (1)

Country Link
JP (1) JP3751085B2 (en)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS593501B2 (en) * 1976-04-30 1984-01-24 三洋化成工業株式会社 soil conditioner
JPS52144110A (en) * 1976-05-26 1977-12-01 Kyokado Eng Co Subsoil solidification method using grout with buffer effect
JP3150380B2 (en) * 1991-09-25 2001-03-26 日本化学工業株式会社 Ground injection agent and its injection method
JP3543877B2 (en) * 1995-09-25 2004-07-21 三井化学株式会社 Soil stabilization method

Also Published As

Publication number Publication date
JPH10102059A (en) 1998-04-21

Similar Documents

Publication Publication Date Title
CN110451838A (en) A kind of novel energy-saving environment-friendly alkali-free quick-coagulant and preparation method thereof
EP0273445B1 (en) Chemical grout for ground injection and method for accretion
US4384894A (en) Composition and process for modifying gelation of alkali metal silicates
JP3751085B2 (en) Soil stabilization method
JPS5849585B2 (en) soil stabilization method
JP2000017259A (en) Ground solidification agent
JP2013136908A (en) Ground improvement method, silica-based grout, and raw material for the same
JPS5826382B2 (en) Ground improvement method
JP4094285B2 (en) Silicate-based soil stabilization chemicals
JP2003119465A (en) Liquefaction-preventing grouting chemical liquid
JPH10324872A (en) Grout for ground and grout injection method
JP4164172B2 (en) Chemical solution for ground injection
JP3949844B2 (en) Silicate soil chemicals
JPS6312514B2 (en)
JPH108054A (en) Soil improvement
JPS5832189B2 (en) Hardening agent for water glass soil stabilizer
JP3543877B2 (en) Soil stabilization method
JP4462608B2 (en) Silicate soil stabilization chemical and ground stabilization method using the same
JPS6216990B2 (en)
JP2987625B1 (en) Ground consolidated material
JP3938949B2 (en) Soil improvement method
JP2002194352A (en) Agent solution for stabilizing ground and method for stabilizing ground with the same
JP5394165B2 (en) Silicate based chemical solution for soil stabilization and ground stabilization method using the same
JPS6247915B2 (en)
JPS58109584A (en) Soil stabilizer

Legal Events

Date Code Title Description
A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20051201

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20051206

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20051206

R150 Certificate of patent (=grant) or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (prs date is renewal date of database)

Free format text: PAYMENT UNTIL: 20091216

Year of fee payment: 4

LAPS Cancellation because of no payment of annual fees