JP2022036294A5 - - Google Patents
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- JP2022036294A5 JP2022036294A5 JP2022004810A JP2022004810A JP2022036294A5 JP 2022036294 A5 JP2022036294 A5 JP 2022036294A5 JP 2022004810 A JP2022004810 A JP 2022004810A JP 2022004810 A JP2022004810 A JP 2022004810A JP 2022036294 A5 JP2022036294 A5 JP 2022036294A5
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- impermeable wall
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- stirring
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- 239000004568 cement Substances 0.000 claims description 91
- 239000002689 soil Substances 0.000 claims description 67
- 239000004576 sand Substances 0.000 claims description 36
- 239000008267 milk Substances 0.000 claims description 35
- 210000004080 milk Anatomy 0.000 claims description 35
- 235000013336 milk Nutrition 0.000 claims description 35
- 238000003756 stirring Methods 0.000 claims description 34
- 238000002156 mixing Methods 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims description 27
- 239000003795 chemical substances by application Substances 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 17
- 239000000463 material Substances 0.000 claims description 12
- 238000012669 compression test Methods 0.000 claims description 9
- 238000007711 solidification Methods 0.000 claims description 9
- 230000008023 solidification Effects 0.000 claims description 9
- 238000011065 in-situ storage Methods 0.000 claims description 8
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 39
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 28
- 238000012360 testing method Methods 0.000 description 26
- 239000000499 gel Substances 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 19
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 14
- 235000017557 sodium bicarbonate Nutrition 0.000 description 14
- 239000004927 clay Substances 0.000 description 11
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 7
- 238000010276 construction Methods 0.000 description 7
- 230000035699 permeability Effects 0.000 description 7
- 239000000440 bentonite Substances 0.000 description 6
- 229910000278 bentonite Inorganic materials 0.000 description 6
- 239000003673 groundwater Substances 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 238000002474 experimental method Methods 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 3
- 238000011835 investigation Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- 238000011041 water permeability test Methods 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- -1 hydrogen salt Chemical class 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 230000002522 swelling effect Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Description
本発明は、原位置撹拌工法による地中遮水壁に関する。 TECHNICAL FIELD The present invention relates to an underground impermeable wall using an in-situ mixing method.
地下水位の調整、汚染水及び汚染土壌の封じ込め、並びに、堤体や調整池の漏水防止等を目的として、地中に連続遮水壁を築造する方法がある。 There is a method of constructing a continuous impermeable wall in the ground for the purpose of adjusting the groundwater level, containing contaminated water and contaminated soil, and preventing water leakage from the embankment body and regulating pond.
特に、地震による液状化対策として、地下水位低下工法が採用されている。地下水位低下工法では、地中に液状化対策をする区域の周辺において地中に連続遮水壁を築造し、その後、井戸等を利用して連続遮水壁に囲まれた地中の地下水位を低下させる。 In particular, as a countermeasure against liquefaction caused by earthquakes, the groundwater level lowering construction method is adopted. In the groundwater level lowering method, a continuous impermeable wall is built in the ground around the area where liquefaction countermeasures are to be taken, and then the underground water level surrounded by the continuous impermeable wall is lowered using a well, etc. lower the
このような、地中に連続遮水壁を築造する方法として、特許文献１に示すようなセメント系固化材を用いたスラリーやセメント・ベントナイトスラリーを地中に注入して撹拌混合して連続遮水壁を地中に築造する方法がある。さらに特許文献２に示すような、セメント系固化材を使用せず、ベントナイトによる地中遮水壁を築造する方法がある。 As a method for constructing a continuous impermeable wall in the ground, a slurry using a cement-based solidifying material or a cement-bentonite slurry as shown in Patent Document 1 is poured into the ground and stirred and mixed to continuously impermeable walls. There is a method of building a wall of water in the ground. Furthermore, there is a method of constructing an underground impermeable wall with bentonite without using a cement-based solidifying material, as shown in Patent Document 2.
特許文献１のセメント系固化材を用いたスラリーやセメント・ベントナイトスラリーによる地中遮水壁は、曲げや引張に対して弱く、柔軟性が極めて低い。また、セメント系固化材及びセメント・ベントナイトの必要量の調整が難しく、地中遮水壁の品質が安定しないという問題もある。また、スラリーを地中で練り混ぜるために大量の水が必要となるという問題もある。 The underground impermeable wall made of the slurry using the cement-based solidifying material or the cement-bentonite slurry of Patent Document 1 is weak against bending and tension, and has extremely low flexibility. Another problem is that it is difficult to adjust the required amount of cement-based solidifying material and cement-bentonite, and the quality of the underground impermeable wall is not stable. Another problem is that a large amount of water is required to knead the slurry underground.
特許文献２のベントナイトによる地中遮水壁は、粘度発現や水膨潤性が乏しく十分な遮水性能が得られない場合があるという問題がある。また、ベントナイトの必要量の調整が難しく、地中遮水壁の品質が安定しないという問題もある。また、排土が大量に生じるという問題がある。 The underground impermeable wall made of bentonite in Patent Document 2 has a problem that it has poor viscosity development and water swelling properties, and sufficient impermeable performance may not be obtained. Another problem is that it is difficult to adjust the necessary amount of bentonite, and the quality of the underground impermeable wall is unstable. Moreover, there is a problem that a large amount of soil is generated.
そこで、上記点より本発明は、十分な遮水性能と変形追随性とを両立する地中遮水壁、及び、地中遮水壁の品質が安定し、かつ、築造おいて環境負荷を抑制できる地中遮水壁築造方法を提供することを目的とする。 Therefore, from the above points, the present invention provides an underground impermeable wall that achieves both sufficient impervious performance and deformation followability, and that the quality of the underground impermeable wall is stable and the environmental load is suppressed during construction. It is an object of the present invention to provide a method for constructing an underground impermeable wall.
請求項１の原位置撹拌工法による地中遮水壁は、炭酸水素塩を含む固化材入りセメントミルクと地盤土砂とを混合撹拌したソイルセメントを固化させて地中に築造される原位置撹拌工法による地中遮水壁であって、ソイルセメントにおいて、炭酸水素塩によるＣ-Ｓ-Ｈゲルの生成が促進されることよって、固化後の前記ソイルセメントは、遮水性を示す透水係数が１０－７ｃｍ／ｓ以下、かつ、材齢７日の強度が一軸圧縮試験で１００ｋＮ／ｍ ２ 以上である。 The underground impermeable wall by the in-situ mixing method of claim 1 is constructed in the ground by solidifying soil cement obtained by mixing and stirring cement milk containing a solidifying agent containing hydrogen carbonate and ground earth and sand. In the soil cement, the hydrogen carbonate promotes the formation of a C—S—H gel, so that the soil cement after solidification has a permeability coefficient of 10 − 7 cm/s or less, and a strength of 100 kN/m 2 or more in a uniaxial compression test at a material age of 7 days .
請求項１の地中遮水壁によれば、遮水性を示す透水係数が１０－７ｃｍ／ｓ以下となっていることによって、地中遮水壁は、事実上不透水レベルとなり、十分な遮水性能を実現できることに加えて、材齢７日の強度が一軸圧縮試験で１００ｋＮ／ｍ ２ 以上となっていることによって地中遮水壁は、十分な強度を実現できる。 According to the underground impermeable wall of claim 1, since the hydraulic conductivity indicating impermeability is 10 −7 cm/s or less, the underground impermeable wall practically reaches the impermeable level and has a sufficient level of impermeability. In addition to being able to achieve impermeable performance, the underground impermeable wall can achieve sufficient strength because the strength at 7 days of age is 100 kN/m 2 or more in a uniaxial compression test.
炭酸水素塩を含む固化材入りセメントミルクと地盤土砂とを混合撹拌したソイルセメントを固化させて地中に築造される地中遮水壁であって、固化させたソイルセメントのＣ－Ｓ－Ｈゲルの端部は、微細な針が多数飛び出している形状となっており、炭酸水素塩を含まない固化材入りセメントミルクと地盤土砂とを混合撹拌し固化させたソイルセメントと比較して、炭酸水素塩を含む固化材入りセメントミルクと地盤土砂を混合撹拌し固化させたソイルセメントのＣ－Ｓ－Ｈゲルの端部の微細な針が太くなっている。 An underground impermeable wall constructed by solidifying soil cement obtained by mixing and stirring cement milk containing a solidifying agent containing hydrogen carbonate and ground earth and sand, wherein the CSH of the solidified soil cement The edge of the gel has a shape in which many fine needles protrude. Fine needles at the ends of the C—S—H gel of soil cement, which is solidified by mixing and stirring cement milk containing a solidifying agent containing a hydrogen salt and ground soil, are thickened.
Ｃ－Ｓ－Ｈゲルの端部の形状は、Ｃ－Ｓ－Ｈゲルの結合の強さに影響を及ぼす。炭酸水素塩を含まない固化材入りセメントミルクと地盤土砂とを混合撹拌し固化させたソイルセメントでは、Ｃ－Ｓ－Ｈゲルの端部の微細な針が比較的細いため、Ｃ－Ｓ－Ｈゲルが互いに複雑に絡み合って、高い結合力が生じる。これに対して、請求項１の地中遮水壁によれば、炭酸水素塩を含む固化材入りセメントミルクと地盤土砂とを混合撹拌し固化させたソイルセメントでは、炭酸水素塩を含まない固化材入りセメントミルクと地盤土砂とを混合撹拌し固化させたソイルセメントと比べて、Ｃ－Ｓ－Ｈゲルの端部の微細な針が比較的太いため、炭酸水素塩を含む固化材入りセメントミルクと地盤土砂とを混合撹拌し固化させたソイルセメントのＣ－Ｓ－Ｈゲルが比較的低い結合力となる。よって、炭酸水素塩を含まない固化材入りセメントミルクと地盤土砂とを混合撹拌し固化させたソイルセメントと比較して、炭酸水素塩を含む固化材入りセメントミルクと地盤土砂とを混合撹拌し固化させたソイルセメントは、地中遮水壁の柔軟性が高まり、変形追随性能を向上させることができる。 The edge shape of the CSH gel affects the bond strength of the CSH gel. In soil cement, which is obtained by mixing and stirring cement milk containing a solidifying agent that does not contain hydrogen carbonate and ground soil and sand, the fine needles at the end of the CSH gel are relatively thin, so CSH The gels are intricately entangled with each other, resulting in high bonding strength. On the other hand, according to the underground impermeable wall of claim 1, soil cement obtained by mixing and stirring cement milk containing a solidifying agent containing hydrogen carbonate and ground soil and sand to solidify does not contain hydrogen carbonate. Compared to soil cement, which is made by mixing and stirring cement milk containing materials and ground soil and sand, the fine needles at the end of CSH gel are relatively thick, so cement milk containing a solidifying material containing bicarbonate is used. C—S—H gel of soil cement, which is obtained by mixing and stirring ground soil and sand and solidifying, has a relatively low binding force. Therefore, compared with soil cement that is solidified by mixing and stirring cement milk containing a solidifying agent that does not contain hydrogen carbonate and ground soil, cement milk containing a solidifying agent that contains hydrogen carbonate and ground soil are mixed and stirred and solidified. The soil cement that has been softened can increase the flexibility of the underground impermeable wall and improve the deformation follow-up performance.
請求項２の原位置撹拌工法による地中遮水壁は、請求項１の原位置撹拌工法による地中遮水壁において、炭酸水素塩を含む固化材入りセメントミルクと地盤土砂とを混合撹拌した固化前のソイルセメントは、さらに、流動性を示すフロー値が１５ｃｍ以上である。 The underground impermeable wall by the in- situ mixing method of claim 2 is obtained by mixing and agitating cement milk containing a solidifying agent containing bicarbonate and ground soil in the underground impermeable wall by the in-situ mixing method of claim 1. The soil cement before hardening further has a flow value of 15 cm or more, which indicates fluidity.
請求項２の地中遮水壁によれば、請求項１の地中遮水壁と同様の作用に加えて、さらに炭酸水素塩を含む固化材入りセメントミルクと地盤土砂とを混合撹拌した固化前のソイルセメントは、流動性を示すフロー値が１５ｃｍ以上となっていることによって、地中遮水壁の築造施工時に、固化前のソイルセメントの不要な拡散を抑制しつつ、所定の位置に固化前のソイルセメントを充填することができる。 According to the underground impermeable wall of claim 2, in addition to the same action as the underground impermeable wall of claim 1 , the cement milk containing the solidifying agent containing hydrogen carbonate and the ground earth and sand are mixed and agitated to solidify. The previous soil cement has a flow value of 15 cm or more, which indicates fluidity. It can be filled with soil cement before hardening.
請求項１から２の原位置撹拌工法による地中遮水壁は、十分な遮水性能と十分な強度とを両立することができる。 The underground impermeable wall by the in-situ mixing method of claims 1 and 2 can achieve both sufficient impervious performance and sufficient strength .
１．１ 固化したソイルセメントの供試体の実験
本発明の地中遮水壁が十分な遮水性能と変形追随性とを両立していることを確認する目的の試験を実施した。
1.1 Experiments on Solidified Soil Cement Specimens A test was conducted to confirm that the underground impermeable wall of the present invention has both sufficient impervious performance and deformation followability .
１．２ 供試体の材料
供試体は、後述する表１中の検討例１～４に示すように、地盤土砂の「標準砂」に、炭酸水素塩である重曹と粘土とセメントと水の配合条件を変えて、それぞれ混合して作製した。比較のための供試体として、後述する表１中の比較例１～２に示すように、「標準砂」に粘土とセメントと水を混合して作製した。
「標準砂」は山口県豊浦エリアでも限定された場所でしか産出されない純粋な天然のシリカサンドである。天然砂の特質は、粉砕された人工のものに比べ、自然界に存在する形状をなしているので、粒に丸みがあり、その特質のため、実験や測定で発生する誤差を小さくし、安定した結果をえることができる硅砂である。
さらに、後述する表２中の検討例５～９に示すように、地盤土砂として、実際に地震後の液状化が発生した「熊本市区内現場土（以下、熊本砂）」に、炭酸水素塩である重曹と粘土とセメントと水の配合条件を変えて、それぞれ混合して作製した。比較のための供試体として、後述する表２中の比較例３に示すように、「熊本砂」に粘土とセメントと水を混合して作製した。
「熊本砂」は、熊本市の液状化した原位置で採取した。熊本砂は、含水比が高く約40%で土の飽和度が100%を越えていたため、含水比20%に調整して使用した。
1.2 Specimen material As shown in Examination Examples 1 to 4 in Table 1 below, the specimen is a mixture of bicarbonate of sodium bicarbonate, clay, cement, and water in "standard sand" of ground soil. They were prepared by mixing under different conditions. As comparative specimens, as shown in Comparative Examples 1 and 2 in Table 1, which will be described later, clay, cement and water were mixed with "standard sand".
"Standard sand" is a pure natural silica sand produced only in limited areas in the Toyoura area of Yamaguchi Prefecture. Compared to pulverized artificial sand, natural sand has a shape that exists in nature, so the grains are round. It is silica sand that can get results.
Furthermore, as shown in Examination Examples 5 to 9 in Table 2, which will be described later, hydrogen carbonate Baking soda, which is a salt, clay, cement, and water were mixed under different mixing conditions. As a test piece for comparison, as shown in Comparative Example 3 in Table 2, which will be described later, clay, cement and water were mixed with " Kumamoto sand ".
"Kumamoto sand" was collected at the liquefied in situ location in Kumamoto City. Kumamoto sand has a high water content of about 40% and the saturation of the soil exceeded 100%, so it was adjusted to a water content of 20% and used.
１．３ 供試体の作製
（１） 用量3000mlのビーカーに水道水300gを投入し、ディスパーに設置する。
（２） ミキサーを700rpmで回転させ、各検討例の配合条件に合わせた量のセメントを投入し3分間攪拌する。
（３） 検討例の供試体では、上記（２）に、各検討例の配合条件に合わせた量の炭酸水素塩である重曹および粘土を投入し5分間攪拌後、固化剤を作製する。比較例の供試体では、上記（２）に、各比較例の配合条件に合わせた量の粘土のみを投入し、5分間攪拌後、固化剤を作製する。
（４） 標準砂又は熊本砂700gに対し、上記（３）の各検討例及び各比較例の固化剤を投入する。
（５） モルタルミキサーにて5分間攪拌し、固化材入りセメントミルクと地盤土砂とを混合撹拌した固化前のソイルセメントを作製する。
（６） 上記（５）の固化材入りセメントミルクと地盤土砂とを混合撹拌したソイルセメントを変水位透水試験用モールドに充填し、各検討例及び各比較例の透水試験用の供試体を作製する。
（７） 上記（５）のセメントミルク及び炭酸水素塩を含む固化材と地盤土砂とを混合撹拌したソイルセメントを一軸圧縮試験用モールドへ投入し、20度±0.5度の恒温槽にて所定期間養生して、各検討例及び各比較例の一軸圧縮試験用の供試体を作製する。
1.3 Preparation of test piece (1) Put 300g of tap water into a 3000ml beaker and set it in a disper.
(2) Rotate the mixer at 700 rpm, add cement in an amount that matches the blending conditions of each study example, and stir for 3 minutes.
(3) For the specimens of the study examples, sodium bicarbonate, which is a hydrogen carbonate, and clay are added to the above (2) in amounts that match the mixing conditions of each study example, and after stirring for 5 minutes, a solidifying agent is prepared. For the specimens of the comparative examples, only clay in an amount matching the blending conditions of each comparative example was added to the above (2), and after stirring for 5 minutes, a solidifying agent was prepared.
(4) To 700 g of standard sand or Kumamoto sand, add the solidifying agent of each study example and each comparative example in (3) above.
(5) Stir with a mortar mixer for 5 minutes to prepare soil cement before solidification by mixing and stirring cement milk containing a solidifying agent and ground soil.
(6) The soil cement obtained by mixing and stirring the cement milk containing the solidifying agent in (5) above and the ground soil is filled into a variable water level permeability test mold to prepare a specimen for the permeability test of each study example and each comparative example. do.
(7) The soil cement obtained by mixing and stirring the solidifying material containing cement milk and bicarbonate in (5) above and ground soil is put into a mold for uniaxial compression test and placed in a constant temperature bath at 20°C ± 0.5°C for a predetermined period. After curing, specimens for the uniaxial compression test of each study example and each comparative example are produced.
１．４ 透水試験（変水位法 JIS A1218/JGS 0311）
透水試験は、比較的に透水性が低い粘性土・シルト質土に用いられる変水位法 JIS A1218/JGS 0311の試験方法を用いて透水係数を測定した。地中遮水壁において、十分な遮水性能を実現できる透水係数の目標値は、10-7cm/sec以下とした。
1.4 Permeability test (fluctuation water level method JIS A1218/JGS 0311)
In the permeability test, the permeability coefficient was measured using the test method of JIS A1218/JGS 0311, which is a changing water level method used for clayey soil and silty soil with relatively low permeability. For underground impermeable walls, the target value of hydraulic conductivity that can achieve sufficient impermeable performance is 10 -7 cm/sec or less.
１．５ 一軸圧縮試験 （JIS A1216/JGS 0511）
一軸圧縮試験は、粘性土の供試体の一軸圧縮強度及び破壊ひずみを求めるものである。試験は、複数の配合パターンで混合された供試体を材齢7日の養生期間を設けて一軸圧縮強度機を用いておこなった。地下水位低下工法による偏土圧に対する安全性を確保するため、地中遮水壁における十分な強度の目標値は、100kN/m2以上とした。また、地中遮水壁において、変形追随性を実現するため、破壊ひずみの目標値は、２％以上とした。
1.5 Uniaxial compression test (JIS A1216/JGS 0511)
The unconfined compression test is to determine the unconfined compression strength and breaking strain of the cohesive soil specimen. The test was conducted using a uniaxial compressive strength machine after setting a curing period of 7 days for a test piece mixed with a plurality of compounding patterns. In order to ensure safety against uneven earth pressure due to the groundwater level lowering method, the target value for the sufficient strength of the underground impermeable wall was set at 100kN/m 2 or more. In addition, the target value of the breaking strain was set to 2% or more in order to realize deformation followability in the underground impermeable wall.
２．１ 固化前のソイルセメントの供試体の実験
また、本発明の地中遮水壁の築造施工時に、セメントミルク及び炭酸水素塩を含む固化材と地盤土砂とを混合撹拌したものが十分な流動性があることを確認する目的の実験も実施した。この実験について、以下に説明する。
2.1 Experiment of soil cement specimen before solidification In addition, when constructing the underground impermeable wall of the present invention, the solidification material containing cement milk and hydrogen carbonate and the ground soil and sand were mixed and agitated sufficiently. An experiment was also conducted to confirm that there is fluidity. This experiment is described below.
２．２ 供試体の材料
供試体は、地中遮水壁が十分な遮水性能と変形追随性とを両立していることを確認する目的の試験と同様に、標準砂の検討例１～４、標準砂の比較例１、２、熊本砂の検討例５～９、及び、熊本砂の比較例３である。
2.2 Materials of the test specimens The test specimens were the same as the test for the purpose of confirming that the underground impermeable wall has both sufficient impervious performance and deformation followability. 4 , Comparative Examples 1 and 2 of standard sand, Investigative Examples 5 to 9 of Kumamoto sand, and Comparative Example 3 of Kumamoto sand.
２．３ 供試体の作製
（１） 用量3000mlのビーカーに水道水300gを投入し、ディスパーに設置する。
（２） ミキサーを700rpmで回転させ、各検討例の配合条件に合わせた量のセメントを投入し3分間攪拌する。
（３） 検討例の供試体では、上記（２）に、各検討例の配合条件に合わせた量の炭酸水素塩である重曹および粘土を投入し5分間攪拌後、固化剤を作製する。比較例の供試体では、上記（２）に、各比較例の配合条件に合わせた量の粘土のみを投入し、5分間攪拌後、固化剤を作製する。
（４） 標準砂又は熊本砂700gに対し、上記（３）の各検討例及び各比較例の固化剤を投入する。
（５） モルタルミキサーにて5分間攪拌し、固化材入りセメントミルクと地盤土砂とを混合撹拌した固化前のソイルセメントのフロー試験用の供試体を作製する。
2.3 Preparation of test piece (1) Put 300g of tap water into a 3000ml beaker and set it in a disper.
(2) Rotate the mixer at 700 rpm, add cement in an amount that matches the blending conditions of each study example, and stir for 3 minutes.
(3) For the specimens of the study examples, sodium bicarbonate, which is a hydrogen carbonate, and clay are added to the above (2) in amounts that match the mixing conditions of each study example, and after stirring for 5 minutes, a solidifying agent is prepared. For the specimens of the comparative examples, only clay in an amount matching the blending conditions of each comparative example was added to the above (2), and after stirring for 5 minutes, a solidifying agent was prepared.
(4) To 700 g of standard sand or Kumamoto sand, add the solidifying agent of each study example and each comparative example in (3) above.
(5) Stir with a mortar mixer for 5 minutes to mix and stir the cement milk containing the solidifying agent and ground soil to prepare a sample for a flow test of the soil cement before solidification.
２．４ フロー試験（JIS A313）
フロー試験は、複数の配合パターンで混合されたソイルセメントの供試体の固化前の流動性を確認した。地中遮水壁の築造施工時に、固化前のソイルセメントの不要な拡散を抑制しつつ、所定の位置に固化前のソイルセメントを充填することができるように、フロー値の目標値は、15cm以上とした。
2.4 Flow test (JIS A313)
Flow tests confirmed the fluidity of soil cement specimens mixed in multiple formulation patterns before setting. The target value of the flow value is 15 cm so that the soil cement before solidification can be filled in the specified position while suppressing unnecessary diffusion of the soil cement before solidification when constructing the underground impermeable wall. That's all.
３．試験結果
標準砂での各検討例及び各比較例の配合条件、透水試験、一軸圧縮試験及びフロー試験の結果を以下の表１に示す。
3. Test Results Table 1 below shows the blending conditions, water permeability test, uniaxial compression test, and flow test results for each study example and each comparative example using standard sand.
標準砂の各検討例及び比較例の中で、標準砂の検討例３と検討例４が、透水係数の目標値10-7cm/sec以下、強度の目標値100kN/m2以上、破壊ひずみの目標値２％以上、及び、フロー値の目標値15cm以上をすべて満たす。 Among the standard sand study examples and comparative examples, study examples 3 and 4 of standard sand have a hydraulic conductivity target value of 10 -7 cm/sec or less, a strength target value of 100 kN/m 2 or more, and a fracture strain of 100 kN/m 2 or more. The target value of 2% or more and the target value of flow value of 15 cm or more are all met.
したがって、地盤土砂の「標準砂」、炭酸水素塩である重曹、粘土、セメント、及び水を適切な配合条件とすることによって、地中遮水壁は、十分な遮水性能と変形追随性とを両立することができる。 Therefore, an underground impermeable wall with sufficient impermeable performance and deformation conformability can be obtained by properly blending the "standard sand" of ground soil, bicarbonate of sodium bicarbonate, clay, cement, and water. can be compatible.
比較例１と比較例２は、セメントの量を多くしたことによって、破壊ひずみの目標値を満たすことができなくなっている。 Comparative Examples 1 and 2 cannot satisfy the target value of the breaking strain due to the increased amount of cement.
標準砂の検討例３と検討例４は、比較例１と比較例２と比べて、少ないセメントの量で、透水係数、強度、破壊ひずみ及びフロー値の目標値を満たすことができる。したがって、地盤土砂の「標準砂」、炭酸水素塩である重曹、粘土、セメント、及び水を適切な配合条件とすることによって、地中遮水壁は、セメントの使用量を抑制することで、経済性が向上し、環境負荷を抑制することができる。 Compared to Comparative Examples 1 and 2, Investigation Examples 3 and 4 , which are standard sands, can satisfy the target values for hydraulic conductivity, strength, breaking strain, and flow value with a smaller amount of cement. Therefore, by setting appropriate blending conditions for the "standard sand" of ground soil, bicarbonate of sodium bicarbonate, clay, cement, and water, the underground impermeable wall can reduce the amount of cement used. Economic efficiency is improved, and environmental load can be suppressed.
熊本砂での各検討例及び各比較例の配合条件、透水試験、一軸圧縮試験及びフロー試験の結果を以下の表２に示す。 Table 2 below shows the blending conditions, water permeability test, uniaxial compression test and flow test results for each study example and each comparative example using Kumamoto sand.
熊本砂の検討例８と検討例９が、透水係数の目標値10-7cm/sec以下、強度の目標値100kN/m2以上、破壊ひずみの目標値２％以上、及び、フロー値の目標値15cm以上をすべて満たす。なお熊本砂の比較例３及び検討例５～７は、供試体が自立することなく、当然強度の目標値を満たしていない。 Investigation example 8 and investigation example 9 of Kumamoto sand have a hydraulic conductivity target value of 10 -7 cm/sec or less, a strength target value of 100 kN/m 2 or more, a fracture strain target value of 2% or more, and a flow value target. Satisfies all values of 15 cm or more. In Comparative Example 3 and Investigative Examples 5 to 7 of Kumamoto sand, the specimens did not stand on their own, and naturally did not meet the target value of strength.
したがって、地盤土砂の「熊本砂」、炭酸水素塩である重曹、粘土、セメント、及び水を適切な配合条件とすることによって、地中遮水壁は、十分な遮水性能と変形追随性とを両立することができる。 Therefore, the ground soil “Kumamoto sand”, bicarbonate of sodium bicarbonate, clay, cement, and water are properly blended to create an underground impermeable wall with sufficient impervious performance and deformation conformability. can be compatible.
セメントミルクに炭酸水素塩である重曹を混入することでＣ－Ｓ－Ｈゲルの生成が促進されるメカニズムについて、以下に説明する。 The mechanism by which C—S—H gel formation is promoted by mixing sodium bicarbonate, which is a bicarbonate, into cement milk will be described below.
セメント組成物である3CaO・SiO2と水との化学反応は以下の通りである。 The chemical reaction between the cement composition 3CaO SiO 2 and water is as follows.
化学式１中の2CaO・SiO2・1.17H2Oは、Ｃ－Ｓ－Ｈゲルの水和物である。 2CaO.SiO 2 .1.17H 2 O in chemical formula 1 is a hydrate of C—S—H gel.
また、セメントミルクに重曹が混入されると、重曹と水による加水分解反応が起こる。 Also, when sodium bicarbonate is mixed with cement milk, a hydrolysis reaction between sodium bicarbonate and water occurs.
化学式２の加水分解反応によって生じたナトリウムイオンによって、化学式１での2CaO・SiO2・1.17H2OのＣ－Ｓ－Ｈゲルの生成が促進されるようになっている。 The sodium ions generated by the hydrolysis reaction of Chemical Formula 2 promote the formation of C—S—H gel of 2CaO.SiO 2 .1.17H 2 O of Chemical Formula 1.
重曹を混入していないセメントミルクからなるソイルセメントの試験体の破断面の実体顕微鏡観察写真を図１に示す。重曹を混入したセメントミルクからなるソイルセメントの試験体の破断面の実体顕微鏡観察写真を図２に示す。 FIG. 1 shows a stereomicroscopic photograph of a fracture surface of a soil cement test piece made of cement milk not mixed with sodium bicarbonate. FIG. 2 shows a stereomicroscopic photograph of a fracture surface of a soil cement test piece made of cement milk mixed with sodium bicarbonate.
各破断面には白色が濃い粒状の点が多数見られる。この白色が濃い粒状の点がＣ－Ｓ－Ｈゲルである。各破断面におけるＣ－Ｓ－Ｈゲルの領域の面積と破断面全体の面積との比率は、重曹を混入していないセメントミルクからなるソイルセメントの試験体では約１０％であり、重曹を混入したセメントミルクからなるソイルセメントの試験体では約１５％である。 A large number of granular dots with a deep white color can be seen on each fracture surface. The white, dense, granular dots are the CSH gel. The ratio of the area of the CSH gel region on each fractured surface to the area of the entire fractured surface was about 10% for the soil cement test specimen made of cement milk without sodium bicarbonate mixed with sodium bicarbonate. It is about 15% for soil cement test specimens made from hardened cement milk.
Ｃ－Ｓ－Ｈゲルは、多孔質であり、吸水して膨張するようになっている。限界まで吸水し膨張したＣ－Ｓ－Ｈゲルは、水を通さない。そのため、地中遮水壁におけるＣ－Ｓ－Ｈゲルの量が多くなればなるほど、遮水性能を向上させることができる。 The C—S—H gel is porous and adapted to absorb water and swell. A CSH gel that has absorbed water to its limit and swelled is impervious to water. Therefore, as the amount of C—S—H gel in the underground impermeable wall increases, the impermeable performance can be improved.
また、Ｃ－Ｓ－Ｈゲルが吸水して膨張することによって、地中遮水壁内部の空隙が充填され、地中遮水壁の自己修復性能が得られる。 In addition, when the CSH gel absorbs water and expands, the voids inside the underground impermeable wall are filled, and the self-healing performance of the underground impermeable wall is obtained.
重曹を混入していないセメントミルクからなるソイルセメントの試験体において、破断面、目視にて観察し、白色生成物であるＣ－Ｓ－Ｈゲルが確認できた箇所から観察用試料を採取した。採取した試料を観察面が上になるように試料台に固定し、導電性を持たせるため、イオンスパッタリング装置にて表面に金を蒸着した後、走査型電子顕微鏡を使用して、図３に示すＣ－Ｓ－Ｈゲルの端部構造を観察できる二次電子像を得た。 The broken surface of the soil cement test piece made of cement milk not mixed with sodium bicarbonate was visually observed, and a sample for observation was collected from a portion where CSH gel, which is a white product, was confirmed. The collected sample was fixed on a sample stage so that the observation surface faced up, and in order to make it conductive, gold was vapor-deposited on the surface using an ion sputtering device. A secondary electron image was obtained in which the edge structure of the C—S—H gel shown can be observed.
重曹を混入したセメントミルクからなるソイルセメントの試験体においても、同様に、図４に示すＣ－Ｓ－Ｈゲルの端部構造を観察できる二次電子像を得た。 Similarly, a secondary electron image was obtained in which the end structure of the C—S—H gel shown in FIG.
図３では、重曹を混入していないセメントミルクからなるソイルセメントのＣ－Ｓ－Ｈゲルの端部が、微細な針が多数飛び出している形状となっている。これに対し、図４では、図３と比較して、重曹を混入したセメントミルクからなるソイルセメントのＣ－Ｓ－Ｈゲルの端部の微細な針が太くなっている。 In FIG. 3, the ends of the soil cement C—S—H gel made of cement milk not mixed with baking soda have a shape in which a large number of fine needles protrude. On the other hand, in FIG. 4, as compared with FIG. 3, the fine needles at the ends of the C—S—H gel of the soil cement made of cement milk mixed with baking soda are thicker.
以下、本発明の地中遮水壁１の築造について説明する。 The construction of the underground impermeable wall 1 of the present invention will be described below.
本発明の地中遮水壁１は、図５に示すように、地中に遮水性能を有する複数の柱状体１０が連なった構成となっている。複数の柱状体１０は、ラップ配置となっている。 As shown in FIG. 5, the underground impermeable wall 1 of the present invention has a structure in which a plurality of columnar bodies 10 having impermeable performance are connected in the ground. The plurality of columnar bodies 10 are arranged in a wrap arrangement.
柱状体１０の施工について、図６を用いて説明する。本発明の地中遮水壁の築造施工で使用する施工機は、昇降及び回転可能に支持されたロッド２と、該ロッドの下に設けられロッド２と一体となって回転する攪拌ヘッド３とを有する。 Construction of the columnar body 10 will be described with reference to FIG. The construction machine used in the construction work of the underground impermeable wall of the present invention comprises a rod 2 supported so as to be vertically and rotatably supported, and a stirring head 3 provided below the rod and rotating integrally with the rod 2. have
図６の（ａ）に示すように、ロッド２の回転軸を柱状体の杭芯位置にセットする。次いで、図６の（ｂ）から（ｃ）に示すように、泥水を撹拌ヘッド３から注入しながらロッド２を回転降下させることによって、撹拌ヘッド３が所定の深度に達するまで、地盤土砂と泥水を撹拌する。次いで、図６の（ｄ）から（ｅ）に示すように、ロッド２を回転上昇させることによって、撹拌ヘッド３がさらに地盤土砂と泥水を撹拌する。 As shown in FIG. 6(a), the rotating shaft of the rod 2 is set at the pile core position of the columnar body. Next, as shown in (b) to (c) of FIG. 6, by rotating and lowering the rod 2 while injecting muddy water from the stirring head 3, the soil and muddy water are mixed until the stirring head 3 reaches a predetermined depth. agitate. Next, as shown in (d) to (e) of FIG. 6, by rotating and raising the rod 2, the agitating head 3 further agitates the soil and muddy water.
次いで、図６の（ｆ）から（ｇ）に示すように、炭酸水素塩を含む固化材入りセメントミルクを撹拌ヘッド３から注入しながらロッド２を回転降下させることによって、撹拌ヘッド３が所定の深度に達するまで、炭酸水素塩を含む固化材入りセメントミルクと地盤土砂と泥水を撹拌する。次いで、図６の（ｈ）から（ｉ）に示すように、ロッド２を回転上昇させることによって、撹拌ヘッド３がさらに地盤土砂と泥水を撹拌する。 Next, as shown in (f) to (g) of FIG. 6, the rod 2 is rotated and lowered while injecting cement milk containing a solidifying agent containing hydrogencarbonate from the stirring head 3, so that the stirring head 3 reaches a predetermined level. Cement milk containing a solidifying agent containing bicarbonate, ground sand and mud water are agitated until the depth is reached. Next, as shown in (h) to (i) of FIG. 6, the stirring head 3 further stirs the soil and muddy water by rotating the rod 2 upward.
図６の（ｊ）に示すように、炭酸水素塩を含む固化材入りセメントミルクと地盤土砂と泥水を撹拌された領域が固化すると、地中遮水壁１を構成する柱状体１０が造成される。 As shown in (j) of FIG. 6, when the cement milk containing the solidifying agent containing hydrogen carbonate, the ground soil, and the muddy water are stirred, the columnar bodies 10 constituting the underground impermeable wall 1 are formed. be.
所定の複数の杭芯位置において、図６（ａ）から（ｅ）の泥水注入の撹拌作業を行った後、図６（ｅ）から（ｉ）のセメントミルク注入の撹拌作業を行って固化すると、複数の柱状体１０が壁状に連なり、地中遮水壁１が築造される。このような地中に遮水性能を有する複数の柱状体１０が連なった構成となった地中遮水壁を、液状化対策する区域の周辺の地中に築造することで、地下水位低下の影響をなくすことができる。 At a plurality of predetermined pile core positions, after performing the stirring work for injecting mud water in FIGS. 6A to 6E, the stirring work for injecting cement milk in FIGS. , a plurality of columnar bodies 10 are connected like a wall, and an underground impermeable wall 1 is constructed. By constructing an underground impermeable wall having a structure in which a plurality of columnar bodies 10 having impermeable performance in the ground are arranged in a row in the ground around the area where liquefaction countermeasures are to be taken, it is possible to reduce the groundwater level. influence can be eliminated.
なお、本発明の実施では、比較的小型の掘削重機で地中遮水壁を築造することができるので、騒音・振動を抑制するとともに、狭い道路や住宅密集地での地中遮水壁の築造することができる。 In the practice of the present invention, the underground impermeable wall can be constructed with a relatively small heavy excavator. can be constructed.
また、図６では、一本の柱状体を造成する場合について説明したが、これに限定されることはない。例えば、複数本の柱状体を同時に造成してもよい。また、トレンチャータイプの重機で柱状体を造成してもよい。 In addition, although FIG. 6 describes the case of forming one columnar body, the present invention is not limited to this. For example, a plurality of columnar bodies may be created at the same time. Alternatively, a trencher-type heavy machine may be used to construct the pillars.
１ 地中遮水壁
２ ロッド
３ 撹拌ヘッド
１０ 柱状体
1 Underground Water Impermeable Wall 2 Rod 3 Stirring Head 10 Columnar Body
Claims (2)
ソイルセメントにおいて、炭酸水素塩によるＣ-Ｓ-Ｈゲルの生成が促進されることよって、固化後の前記ソイルセメントは、遮水性を示す透水係数が１０－７ｃｍ／ｓ以下、かつ、材齢７日の強度が一軸圧縮試験で１００ｋＮ／ｍ ２ 以上であることを特徴とする原位置撹拌工法による地中遮水壁。 An underground impermeable wall constructed by an in-situ mixing method, which is constructed in the ground by solidifying soil cement obtained by mixing and stirring cement milk containing a solidifying agent containing hydrogen carbonate and ground earth and sand,
In soil cement, the formation of C—S—H gel is promoted by hydrogen carbonate, so that the soil cement after solidification has a hydraulic conductivity indicating water impermeability of 10 −7 cm / s or less and a material age. An underground impermeable wall by the in-situ stirring method , characterized by having a strength of 100 kN/m 2 or more in a 7-day uniaxial compression test .
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| JP2019168572A Active JP7169666B2 (en) | 2019-09-17 | 2019-09-17 | Underground impermeable wall and underground impermeable wall construction method |
| JP2021036085A Active JP7266311B2 (en) | 2019-09-17 | 2021-03-08 | Underground Impermeable Wall by In-Situ Stirring Method and Construction Method of Underground Impermeable Wall by In-Situ Stirring |
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| JPH0633058A (en) * | 1992-07-13 | 1994-02-08 | Asahi Chem Ind Co Ltd | Quick limy ground improving agent comprising calcium silicate hydrate |
| JP2813878B2 (en) * | 1996-09-27 | 1998-10-22 | 株式会社テクノサンライズ | Soil pollution treatment method |
| JP3554496B2 (en) | 1998-12-02 | 2004-08-18 | 株式会社鴻池組 | Method for fluidizing soil cement and superplasticizer for soil cement |
| JP2007217255A (en) | 2006-02-20 | 2007-08-30 | Terunaito:Kk | Method of preparing soil cement slurry |
| JP4816193B2 (en) | 2006-03-29 | 2011-11-16 | 栗田工業株式会社 | Construction method of underground wall |
| JP5317938B2 (en) | 2008-11-28 | 2013-10-16 | 学校法人早稲田大学 | Construction method of soil cement pillar and soil cement continuous wall |
| JP4616419B1 (en) * | 2010-06-14 | 2011-01-19 | 明雄 宮本 | Penetrant penetration device |
| JP2013019216A (en) | 2011-07-13 | 2013-01-31 | Asahi Kasei Construction Materials Co Ltd | Impermeable wall mixed with fiber rubber and construction method of the same |
| JP5504414B1 (en) | 2013-09-18 | 2014-05-28 | 強化土株式会社 | Repair method for concrete structures |
| JP6230883B2 (en) * | 2013-11-19 | 2017-11-15 | 徳倉建設株式会社 | Delay hardening type fluidized soil and filling method of underground cavities |
| JP5999718B2 (en) | 2014-03-12 | 2016-09-28 | 株式会社鴻池組 | Underground impermeable wall construction material |
| JP6649774B2 (en) | 2016-01-13 | 2020-02-19 | デンカ株式会社 | Weed control material and method of using it |
| KR101874380B1 (en) * | 2016-10-04 | 2018-08-02 | 이엑스티(주) | Point Foundation Structure Construction Method |
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