JP6312365B2 - Ground injection method - Google Patents
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- JP6312365B2 JP6312365B2 JP2013059218A JP2013059218A JP6312365B2 JP 6312365 B2 JP6312365 B2 JP 6312365B2 JP 2013059218 A JP2013059218 A JP 2013059218A JP 2013059218 A JP2013059218 A JP 2013059218A JP 6312365 B2 JP6312365 B2 JP 6312365B2
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- 239000007924 injection Substances 0.000 title claims description 129
- 238000002347 injection Methods 0.000 title claims description 129
- 238000000034 method Methods 0.000 title claims description 40
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 83
- 239000000463 material Substances 0.000 claims description 56
- 239000000377 silicon dioxide Substances 0.000 claims description 37
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 27
- 239000000920 calcium hydroxide Substances 0.000 claims description 27
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 27
- 230000010349 pulsation Effects 0.000 claims description 13
- 239000010419 fine particle Substances 0.000 description 42
- 239000002245 particle Substances 0.000 description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 230000035699 permeability Effects 0.000 description 11
- 239000002270 dispersing agent Substances 0.000 description 10
- 239000002002 slurry Substances 0.000 description 9
- 239000004576 sand Substances 0.000 description 8
- 239000004568 cement Substances 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- 238000010276 construction Methods 0.000 description 5
- 239000007943 implant Substances 0.000 description 4
- 239000002689 soil Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- PSZYNBSKGUBXEH-UHFFFAOYSA-N naphthalene-1-sulfonic acid Chemical compound C1=CC=C2C(S(=O)(=O)O)=CC=CC2=C1 PSZYNBSKGUBXEH-UHFFFAOYSA-N 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000003204 osmotic effect Effects 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- LFYJSSARVMHQJB-QIXNEVBVSA-N bakuchiol Chemical compound CC(C)=CCC[C@@](C)(C=C)\C=C\C1=CC=C(O)C=C1 LFYJSSARVMHQJB-QIXNEVBVSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 238000001802 infusion Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000010617 multipoint ground Methods 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 239000004848 polyfunctional curative Substances 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 210000003462 vein Anatomy 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Description
本発明は、地盤に対して優れた浸透性を有する注入材を注入し、形成された注入改良体が良好なせん断弾性係数を示し、例えば、液状化対策として使用することができる地盤注入工法に関する。 The present invention relates to a soil injecting method in which an injection material having excellent permeability to the ground is injected, and the formed improved injection body exhibits a good shear elastic modulus and can be used, for example, as a countermeasure against liquefaction. .
２０１１年３月に発生した東北地方太平洋沖地震では、東北から関東にかけて広範囲で液状化が発生した。
液状化が発生した箇所は埋立地など人工地盤がほとんどであり、多くの戸建住宅が沈下や傾斜し、上下水道・ガスといったライフラインや道路が甚大な被害を受けた。
この地震を契機に、地盤工学会の委員会における提言では、既設のインフラ及び宅地における経済的・効果的な液状化対策工法の技術開発が必要であるとされている。
しかしながら、構造物直下や狭隘部で液状化対策を行う場合には、周辺環境への影響や敷地の制約上、ローラーなどで締め固める工法である締固め工法や、強固に締め固めた砂杭を地中に造成して地盤を改良する密度増大工法などは、比較的安価であるが、対象地盤を上部から改良する工法であるため、採用が難しい。
一方、地盤注入工法は、施工機械が小型でありまた高圧噴射撹拌工法に比べて排泥などの建設副産物の発生が無い特徴があり、従来は超微粒子セメント系注入材や溶液型注入材が使用されてきた。
In the 2011 off the Pacific coast of Tohoku Earthquake that occurred in March 2011, liquefaction occurred in a wide area from Tohoku to Kanto.
Most of the land where liquefaction occurred was artificial ground such as landfills, and many detached houses subsided and inclined, causing serious damage to lifelines and roads such as water and sewage and gas.
As a result of this earthquake, the proposal of the Committee of the Geotechnical Society states that it is necessary to develop technology for an economical and effective liquefaction countermeasure method for existing infrastructure and residential land.
However, when liquefaction measures are taken directly under the structure or in narrow spaces, due to the impact on the surrounding environment and site restrictions, a compacting method that is compacted with a roller or a sand pile that has been compacted firmly. The density increasing method for improving the ground by creating in the ground is relatively inexpensive, but is difficult to adopt because it is a method for improving the target ground from above.
On the other hand, the ground injection method is characterized in that the construction machine is compact and there is no generation of construction by-products such as waste mud compared to the high-pressure jet agitation method. Conventionally, ultra fine cement-based injections and solution type injections are used. It has been.
超微粒子セメント系注入材は、最大粒径が15μｍ程度であり、溶液型注入材に比べ耐久性は高いが、シルトや砂質地盤に注入する場合は浸透性の点で課題があった（特許文献１）。
セメントの粒径をさらに小さくすることで浸透性は高まるが、粉体の粒径が小さくなるにつれて粒子は凝集しやすくなり、また水と接触直後から水和によりセメントが肥大化するため、浸透性に限界があった。
The ultra-fine cement cement-based injection material has a maximum particle size of about 15μm and is more durable than the solution-type injection material, but there is a problem in terms of permeability when injected into silt or sandy ground (patent) Reference 1).
The permeability increases by further reducing the particle size of the cement, but as the particle size of the powder becomes smaller, the particles tend to aggregate, and the cement becomes enlarged due to hydration immediately after contact with water. There was a limit.
一方、溶液型注入材としては、例えば、水ガラスやシリカゾルからなる注入材が挙げられ、浸透性が良好で優れることが提案されている（特許文献２、３、４）。
しかしながら、せん断弾性係数が小さいことと、貝殻を含む地盤においては、注入材として酸性反応剤を使用すると、酸性反応剤と貝殻との反応により炭酸ガスが発生し強度が低下することなどの課題があった。
On the other hand, examples of the solution-type injection material include an injection material made of water glass or silica sol, and it has been proposed that the permeability is good and excellent (Patent Documents 2, 3, and 4).
However, in the ground including a shell and a shell including a shell, when an acidic reactant is used as an injection material, problems such as carbon dioxide gas is generated due to the reaction between the acidic reactant and the shell and the strength is lowered. there were.
そこで、高浸透の微粒子シリカを主体とする注入材が提案された（特許文献５、６）。
しかしながら、この注入材では、剛性が高くなり、破壊の仕方が脆性的で変形追随性の確保が難しくなるなどの課題があった。
強度が高いことや剛性が高いことは必ずしも悪いことではないが、高すぎる場合、後日構造物を作るときに掘削等がしにくくなることや基礎地盤の沈下によりクラックが生じ、水みちができるなどの課題があった。
Accordingly, an injection material mainly composed of highly permeable fine particle silica has been proposed (Patent Documents 5 and 6).
However, this injection material has problems such as high rigidity, a brittle manner of fracture, and difficulty in ensuring deformation followability.
High strength and high rigidity are not necessarily bad, but if it is too high, it will be difficult to excavate later when making structures, cracks will occur due to subsidence of the foundation ground, etc. There was a problem.
一方、地盤改良材を、複数の吐出口から地盤中の複数の注入ポントを通してそれぞれ最も適した注入速度、注入圧力で、かつ、一括管理のもとに多点注入する多点地盤注入工法が提案された（特許文献７）。
しかしながら、特許文献７には、所定の濃度の微粒子シリカと微粒子水酸化カルシウムを使用することによって、優れた浸透性を有する注入材とすること、注入後に形成される注入改良体のせん断弾性係数を最適にすることなどについては全く記載がない。
On the other hand, a multi-point ground injection method is proposed in which ground improvement materials are injected at multiple points through multiple injection ports in the ground from the multiple discharge ports at the most suitable injection speed, injection pressure, and batch control. (Patent Document 7).
However, Patent Document 7 discloses that an injection material having excellent permeability by using fine particle silica and fine particle calcium hydroxide at a predetermined concentration, and a shear elastic modulus of an injection improvement body formed after injection. There is no mention of optimizing.
本発明の目的は、地盤に対して優れた浸透性を有する注入材を注入し、形成された注入改良体が最適なせん断弾性係数を有する地盤注入工法を提供することにある。 An object of the present invention is to provide a ground injection method in which an injection material having excellent permeability to the ground is injected and the formed improved injection body has an optimum shear elastic modulus.
本発明は、上記の課題を解決するために、以下の手段を採用する。
（１）シルト及び／又は砂質地盤に浸透注入する地盤注入工法において、微粒子球状シリカ濃度が0.1質量％以上５質量％未満、微粒子水酸化カルシウム濃度が0.1質量％以上５質量％未満の注入材を、0.5MPa以下の注入圧力、10リットル／分以下の注入速度及び５％以下の脈動率で注入することを特徴とする地盤注入工法である。
（２）前記の地盤注入工法で形成された注入改良体のせん断弾性係数が50〜1,000MN/m2であることを特徴とする前記（１）の地盤注入工法である。
（３）液状化対策として用いることを特徴とする前記（１）又は（２）の地盤注入工法である。
The present invention employs the following means in order to solve the above problems.
(1) In the ground injection method for infiltrating and injecting into silt and / or sandy ground, the injection material having a fine spherical silica concentration of 0.1% by mass to less than 5% by mass and a fine calcium hydroxide concentration of 0.1% by mass to less than 5% by mass. Is injected at an injection pressure of 0.5 MPa or less, an injection speed of 10 liters / minute or less, and a pulsation rate of 5% or less.
(2) the shear modulus of the implant improved body formed of ground grouting of the is ground grouting of the (1), which is a 50~1,000MN / m 2.
( 3 ) The ground injection method according to (1) or (2) , which is used as a countermeasure against liquefaction.
本発明により、例えば、液状化する恐れのあるシルト及び／又は砂質地盤に注入することによって、良好な浸透性を示し、その注入改良体が、均一で、最適な範囲のせん断弾性係数を有する注入工法を提供することが可能となる。 In accordance with the present invention, for example, when injected into silt and / or sandy ground where there is a risk of liquefaction, it exhibits good permeability and its injection improvement has a uniform and optimal range of shear modulus. An injection method can be provided.
本発明に記載する部や％は、記載が無い限りは、質量部、質量％を意味する。 Unless otherwise indicated, parts and% described in the present invention mean parts by mass and% by mass.
以下、本発明の実施の形態につき具体的に説明する。 Hereinafter, embodiments of the present invention will be specifically described.
本発明で注入するシルト及び／又は砂質地盤は、土質学的にシルトに分類される粒径５〜74μｍや、砂に分類される74μｍ〜２ｍｍのシルト及び／又は砂質の地盤をいう。
シルト地盤とは、粘土ほどの粘りけがないが、砂ほど粒が大きく、さらさらしていない、粘土と砂の中間の性質をもつ粒子からなる地盤であり、砂質地盤とは、粘着性のない粒の粗い粒子の砂が、締まりが緩い状態で、積み重なっている地盤である。
The silt and / or sandy ground to be injected in the present invention refers to a silt and / or sandy ground having a particle size of 5 to 74 μm classified into silt and 74 μm to 2 mm classified into sand.
Silt ground is not as sticky as clay, but is as large as sand and is not smooth, consisting of particles with intermediate properties between clay and sand. Sandy ground is not sticky. Coarse grained sand is the ground piled up with loose tightening.
シルト及び／又は砂質地盤の粒子間には広い隙間があり、粒子が、互いにつながって全体を支えている。地下水面が高いと、この隙間は水で完全に満たされている。
ここに、地震動が加わり、粒子が繰り返し揺すられると、お互いの支えがはずれ、粒子間の接触はなくなり、粒子は水の中にばらばらになって浮いた状態になる。これが、地盤の液状化である。
There is a wide gap between the particles of the silt and / or sandy ground, and the particles are connected to each other to support the whole. If the groundwater level is high, this gap is completely filled with water.
Here, when earthquake motion is applied and the particles are repeatedly shaken, the support of each other is lost, there is no contact between the particles, and the particles fall apart in the water and float. This is the liquefaction of the ground.
本発明は、粒子の隙間に注入材を充填することにより、例えば、液状化を防ぎ、良好な地盤を形成することを目的とするものである。
ただし、細粒土やれきを50％程度含む地盤であっても、本発明の注入工法を採用することにより、良好な浸透性で最適な範囲のせん断弾性係数を有する、均一な注入改良体を提供することが可能である。
An object of the present invention is, for example, to prevent liquefaction and form a good ground by filling the gaps between particles with an injection material.
However, even in the ground containing about 50% of fine-grained soil and debris, by adopting the injection method of the present invention, it is possible to obtain a uniform injection improved body having good permeability and an optimal range of shear elastic modulus. It is possible to provide.
地盤への注入形態には、注入材が土粒子の隙間を押し広げることなく移動する浸透注入と、部分的に土粒子を押し広げて脈状に入る割裂注入がある。
均一な注入改良体を得るには、浸透注入が望ましいが、注入材の粒径が大きかったり、注入材の濃度が高かったり、注入圧力が高かったり、注入速度が大きかったり、脈動率が高いと割裂注入となる可能性が高くなる。従って、最適な注入材の粒径、注入材の濃度、注入圧力、注入速度、及び脈動率を選択することにより、最適な範囲のせん断弾性係数を有する、均一な注入改良体を得ることができる。
There are two types of injections into the ground: osmotic injection in which the injection material moves without expanding the gap between the soil particles, and split injection that partially expands the soil particles and enters into a vein shape.
In order to obtain a uniform injection improvement body, osmotic injection is desirable, but when the particle size of the injection material is large, the concentration of the injection material is high, the injection pressure is high, the injection speed is high, or the pulsation rate is high. The possibility of split injection is increased. Therefore, by selecting the optimal injection material particle size, injection material concentration, injection pressure, injection speed, and pulsation rate, a uniform injection improvement body having an optimal range of shear modulus can be obtained. .
地盤に注入材を注入することによって、改良した地盤などを注入改良体という。
また、液状化など地震による事象に対抗する評価として、変形特性を求めるため、注入改良体のせん断弾性係数を測定する。
注入改良体のせん断弾性係数は、50〜1,000MN/m2が好ましく、100〜500MN/m2がより好ましい。せん断弾性係数が1,000MN/m2を超えるとせん断弾性係数が大きすぎるため、地震により、後日構造物を作るときに再掘削等がしにくくなったり、基礎地盤の沈下によりクラックが生じたりして、建物や上下水管やガス管等、地中のライフラインの損傷が大きくなる恐れがあり、逆に、せん断弾性係数が50MN/m2未満だと注入の効果が小さいため、均一な注入改良体が得られない場合があり、また、比較的大きな地震発生時に液状化する恐れがある。
せん断弾性係数を最適な範囲にするためには、最適な注入材の粒径、注入材の濃度、注入圧力、注入速度、及び／又は脈動率を選択することが必要である。
The improved ground by injecting an injection material into the ground is called an improved injection body.
In addition, as an evaluation against earthquakes such as liquefaction, the shear elastic modulus of the injection improvement body is measured in order to obtain deformation characteristics.
Shear modulus of the implant improved body is preferably 50~1,000MN / m 2, 100~500MN / m 2 is more preferable. Since the shear modulus is more than 1,000MN / m 2 shear modulus is too large, an earthquake, or become rather Ku the re-digging and the like is when making later structures, cracks or caused by subsidence of the foundation ground If the shear modulus is less than 50 MN / m 2 , the injection effect is small, so uniform injection is possible. An improved body may not be obtained, and there is a risk of liquefaction when a relatively large earthquake occurs.
In order to bring the shear modulus to an optimal range, it is necessary to select an optimal injection material particle size, injection material concentration, injection pressure, injection speed, and / or pulsation rate.
本発明では、微粒子シリカと微粒子水酸化カルシウムを注入材として使用する。
本発明の微粒子シリカや微粒子水酸化カルシウムは、あらかじめ各々を水に分散しスラリー化することによって、注入工事を効率的に行うことができる。
In the present invention, fine particle silica and fine particle calcium hydroxide are used as the injection material.
The fine particle silica and fine particle calcium hydroxide of the present invention can be efficiently injected by dispersing each of them in water in advance to form a slurry.
微粒子シリカとは、微粒子球状シリカ（例えば、デンカＳＦＰ２０Ｍ）やシリカフユームなどのシリカ質物質であり、その粒度は、地盤への浸透性の点で平均粒径1.0μｍ以下が好ましく、0.1〜1.0μｍがより好ましい。
微粒子シリカは水と混合して使用するもので、その濃度は、0.1％以上５％未満であり、0.5〜３％がより好ましい。微粒子シリカ濃度が５％以上では、割裂注入となり、微粒子水酸化カルシウムとの配合割合のバランスで、その注入改良体のせん断弾性係数が1,000MN/m2を超え、再掘削等がしにくくなったり、基礎地盤の沈下によりクラックが生じたりする恐れがあることから好ましくない。また、微粒子シリカ濃度が0.1％未満では、せん断弾性係数が小さすぎて、均一な注入改良体が得られない場合がある。
The fine-particle silica is a siliceous material such as fine-particle spherical silica (for example, Denka SFP20M) or silica fumes, and its particle size is preferably an average particle size of 1.0 μm or less in terms of permeability to the ground, and preferably 0.1 to 1.0 μm. More preferred.
The fine particle silica is used by mixing with water, and the concentration thereof is 0.1% or more and less than 5%, and more preferably 0.5 to 3%. In fine particulate silica concentration of 5% or more, becomes Wari裂injection, the balance of the mixing ratio of the fine particles of calcium hydroxide, the shear modulus of the implant improved body exceeds 1,000MN / m 2, rather Ku the re-digging and the like is It is not preferable because there is a risk of cracking due to settlement of the foundation ground. On the other hand, if the fine particle silica concentration is less than 0.1%, the shear elastic modulus may be too small to obtain a uniform injection improved body.
微粒子水酸化カルシウムとは、水酸化カルシウムを微粉砕した微粒子水酸化カルシウムが挙げられ、その粒度は、地盤への浸透性の点で平均粒径1.0μｍ以下が好ましく、0.1〜1.0μｍがより好ましい。
微粒子水酸化カルシウムは水と混合して使用するもので、その濃度は、0.1％以上５％未満であり、0.5〜３％がより好ましい。微粒子水酸化カルシウム濃度が５％以上では、割裂注入となり、微粒子シリカとの配合割合のバランスで、その注入改良体のせん断弾性係数が1,000MN/m2を超え、再掘削等がしにくくなったり、基礎地盤の沈下によりクラックが生じたりする恐れがあることから好ましくない。また、微粒子水酸化カルシウム濃度が0.1％未満では、せん断弾性係数が小さすぎて、均一な注入改良体が得られない場合がある。
The fine particle calcium hydroxide includes fine particle calcium hydroxide obtained by finely pulverizing calcium hydroxide, and the particle size is preferably an average particle size of 1.0 μm or less, more preferably 0.1 to 1.0 μm in terms of permeability to the ground. .
The fine particle calcium hydroxide is used by mixing with water, and the concentration thereof is 0.1% or more and less than 5%, and more preferably 0.5 to 3%. In particulate calcium hydroxide concentration of 5% or more, becomes Wari裂injection, the balance of the blend ratio of the particulate silica, the shear modulus of the implant improved body exceeds 1,000MN / m 2, rather Ku the re-digging and the like is It is not preferable because there is a risk of cracking due to settlement of the foundation ground. On the other hand, if the fine particle calcium hydroxide concentration is less than 0.1%, the shear elastic modulus is too small and a uniform injection improved body may not be obtained.
本発明の注入材として、具体的には、例えば、電気化学工業社製商品名「シリカボール」が使用可能である。微粒子シリカ濃度が10〜60％の微粒子シリカスラリー、例えば、電気化学工業社製商品名「シリカボール主材」、微粒子水酸化カルシウム濃度が10〜50％の微粒子水酸化カルシウムスラリー、例えば、電気化学工業社製商品名「シリカボール硬化材」を水で希釈することにより、微粒子シリカ濃度が0.1％以上５％未満、微粒子水酸化カルシウム濃度が0.1％以上５％未満の注入材を作製することができる。 Specifically, for example, trade name “Silica Ball” manufactured by Denki Kagaku Kogyo Co., Ltd. can be used as the injection material of the present invention. Fine silica slurry having a fine silica concentration of 10 to 60%, for example, trade name “Silica ball main material” manufactured by Denki Kagaku Kogyo Co., Ltd. Fine fine calcium hydroxide slurry having a fine calcium hydroxide concentration of 10 to 50%, for example, electrochemical By diluting the trade name “Silica Ball Curing Material” manufactured by Kogyo Co., Ltd. with water, an injection material having a fine particle silica concentration of 0.1% to less than 5% and a fine particle calcium hydroxide concentration of 0.1% to less than 5% can be produced. it can.
微粒子シリカと微粒子水酸化カルシウムの配合割合は、微粒子シリカ100部に対して、微粒子水酸化カルシウム30〜300部が好ましい。この範囲外では、剛性が極めて小さくなる恐れがある。 The mixing ratio of fine particle silica and fine particle calcium hydroxide is preferably 30 to 300 parts of fine particle calcium hydroxide with respect to 100 parts of fine particle silica. Outside this range, the stiffness may be very small.
微粒子シリカのスラリーをＡ材、微粒子水酸化カルシウムのスラリーをＢ材とすると、各々のスラリーはできるだけ高濃度とし、施工時に水で希釈して使用することが輸送コスト低減のうえから好ましい。本発明のＡ材中の微粒子シリカ、Ｂ材中の微粒子水酸化カルシウムの濃度は、それぞれ20％以上が好ましく、粘度が高くなる場合は、事前に分散剤を添加することが望ましい。施工時に、Ａ材、Ｂ材を水で希釈し、微粒子シリカ濃度を0.1％以上５％未満、微粒子水酸化カルシウム濃度を0.1％以上５％未満として地盤に注入する。 When the slurry of fine particle silica is A material, and the slurry of fine particle calcium hydroxide is B material, it is preferable to make each slurry as high as possible and dilute with water at the time of construction from the viewpoint of reducing transportation cost. The concentrations of the fine particle silica in the A material and the fine particle calcium hydroxide in the B material of the present invention are each preferably 20% or more, and when the viscosity increases, it is desirable to add a dispersant in advance. At the time of construction, the A and B materials are diluted with water and injected into the ground with a fine particle silica concentration of 0.1% to less than 5% and a fine particle calcium hydroxide concentration of 0.1% to less than 5%.
本発明の地盤に注入材を注入する地盤注入工法において、対象地盤がシルト及び／又は砂質地盤の場合、その注入圧力は一般的な注入工法よりも小さくする必要があり、0.5MPa以下であることが好ましく、0.2MPa以下であることがより好ましい。注入圧力が0.5MPaを超えると割裂注入が主体となり、均一な注入改良体が得られない場合やせん断弾性率が低下する場合がある。 In the ground injection method for injecting the injection material into the ground of the present invention, when the target ground is silt and / or sandy ground, the injection pressure needs to be smaller than that of a general injection method, and is 0.5 MPa or less. It is preferably 0.2 MPa or less. When the injection pressure exceeds 0.5 MPa, split injection is mainly performed, and a uniform improved injection body may not be obtained, and the shear modulus may be lowered.
また、シルト及び／又は砂質地盤に浸透注入する注入工法において、注入性の点から、注入速度が10リットル／分以下となるようにして注入することが好ましく、注入速度が７リットル／分以下となるようにして注入することがより好ましい。 In addition, in the infusion method for infiltrating and injecting into silt and / or sandy ground, in terms of injectability, it is preferable to inject so that the injection rate is 10 liters / minute or less, and the injection rate is 7 liters / minute or less. It is more preferable to inject such that.
さらに、シルト及び／又は砂質地盤に浸透注入する注入工法において、注入性の点から、脈動率が５％以下となるようにして注入することが好ましく、脈動率が３％以下となるようにして注入することがより好ましい。
ここで、脈動率とは、注入速度の最大値と最小値の差を平均注入速度で割った値をいう。
Furthermore, in the injection method for infiltrating and injecting into silt and / or sandy ground, in terms of injectability, it is preferable to inject so that the pulsation rate is 5% or less, and the pulsation rate is 3% or less. More preferably, it is injected.
Here, the pulsation rate means a value obtained by dividing the difference between the maximum value and the minimum value of the injection rate by the average injection rate.
これらの注入圧力、注入速度、及び脈動率を達成する方法としては、例えば、超多点注入工法などの結束細管多点注入工法や、二重管ダブルパッカ注入工法、及び二重管ストレーナ注入工法等が挙げられる。このうち、上記条件を容易に達成するための注入工法である超多点注入工法を使用することが好ましい。 Examples of methods for achieving these injection pressure, injection speed, and pulsation rate include, for example, a bundled tube multi-point injection method such as a super multi-point injection method, a double tube double packer injection method, and a double tube strainer injection method. Is mentioned. Among these, it is preferable to use a super multi-point injection method which is an injection method for easily achieving the above conditions.
ここで、超多点注入工法とは、数十から数百という多数のノズルを地盤中に配置し、各ノズルから低吐出注入で、同時に注入する注入工法である。
この工法によれば、均一な改良地盤を確実に形成することができ、経済的にも優れている。
Here, the super multi-point injection method is an injection method in which a large number of dozens to hundreds of nozzles are arranged in the ground, and injection is performed simultaneously from each nozzle with low discharge injection.
According to this construction method, a uniform improved ground can be reliably formed, which is economically superior.
本発明の注入工法は、広く地盤の改良目的に使用できるが、シルト及び／又は砂質地盤に浸透注入可能である特徴を生かし、液状化対策として用いることが好ましい。液状化は、主に、ゆるく堆積したシルト及び／又は砂質地盤が、地震などの振動により液体のような泥水状態になってしまう現象である。液状化が起こると、砂混じりの水が地表面に噴き出したり、部分的に陥没したりして、建物や地中に埋設していた配管類に損傷を与える。 The injection method of the present invention can be widely used for the purpose of improving the ground, but it is preferable to use it as a countermeasure against liquefaction by taking advantage of the feature that it can be injected into silt and / or sandy ground. Liquefaction is a phenomenon in which loosely accumulated silt and / or sandy ground is mainly made into a liquid-like muddy water state due to vibration such as an earthquake. When liquefaction occurs, water mixed with sand erupts to the ground surface or partially sinks, damaging the buildings and piping buried in the ground.
本発明では、微粒子シリカのスラリー、微粒子水酸化カルシウムのスラリー、それぞれに分散剤を併用することが好ましい。 In the present invention, it is preferable to use a dispersant in each of the slurry of fine particle silica and the slurry of fine particle calcium hydroxide.
本発明で使用する分散剤としては、ナフタレンスルホン酸系、リグニンスルホン酸系、メラミンスルホン酸系、ポリカルボン酸系、及びポリエーテル系の分散剤が挙げられるが、これらのうち、ナフタレンスルホン酸系分散剤が浸透性の点で好ましい。
分散剤の使用量は固形分換算で、微粒子シリカと微粒子水酸化カルシウムの合計量に対して１〜20％が好ましく、３〜10％がより好ましい。
Examples of the dispersant used in the present invention include naphthalenesulfonic acid-based, ligninsulfonic acid-based, melaminesulfonic acid-based, polycarboxylic acid-based, and polyether-based dispersants. Among these, naphthalenesulfonic acid-based dispersants A dispersant is preferred from the viewpoint of permeability.
The amount of the dispersant used is preferably from 1 to 20%, more preferably from 3 to 10%, based on the total amount of fine particle silica and fine particle calcium hydroxide in terms of solid content.
本発明の注入材を地盤に注入するにあたっては、Ａ材とＢ材とを混合する方法として、二重管を用いて先端部でＡ材とＢ材を合流混合して注入するいわゆる２ショット方式、Ａ材とＢ材の両液を注入ポンプから注入管に至る途中で合流混合して注入するいわゆる１．５ショット方式、更にミキサー等の調合槽でＡ材又はＢ材を調合した後、他液を加える１ショット方式いずれの方式でも行うことができる。 When injecting the injection material of the present invention into the ground, as a method of mixing the A material and the B material, a so-called two-shot method in which the A material and the B material are mixed and injected at the tip using a double pipe. The so-called 1.5 shot system in which both liquids of material A and material B are mixed and injected on the way from the injection pump to the injection tube, and further after preparing material A or material B in a mixing tank such as a mixer, etc. Any one-shot method in which liquid is added can be used.
以下、本発明を実験例によって説明するが、本発明はこれらの実験例に限定されるものではない。 Hereinafter, the present invention will be described with reference to experimental examples, but the present invention is not limited to these experimental examples.
実験例１
表１に示す微粒子シリカと微粒子水酸化カルシウムの配合になるように、デンカ シリカボール主材とデンカ シリカボール硬化材をそれぞれ水で希釈して、混合して注入材とした。
最大ドラム径550mmで、200リットルのドラム缶に、試験用調整砂を充填し、表１に示すように、注入材の濃度を変えて超多点注入工法用装置（日本基礎技術社製）を用いて各42リットル注入した。注入時の注入圧力は0.1MPa、注入速度は５リットル／分、及び脈動率は1.0％である。20℃で１カ月養生後、ドラム缶から球状の注入改良体を取り出し、改良径とせん断弾性係数を測定し、注入形態を評価した。
また比較のため、注入材α、注入材βの注入を同様に行った。
Experimental example 1
Denka silica ball main material and Denka silica ball hardened material were each diluted with water so as to have the composition of fine particle silica and fine particle calcium hydroxide shown in Table 1, and mixed to prepare an injection material.
A 200-liter drum can with a maximum drum diameter of 550 mm is filled with test adjustment sand, and as shown in Table 1, using a super multi-point injection method device (manufactured by Nippon Basic Technology Co., Ltd.) with different concentrations of injection material 42 liters of each were injected. The injection pressure at the time of injection is 0.1 MPa, the injection speed is 5 liters / minute, and the pulsation rate is 1.0%. After curing at 20 ° C. for one month, a spherical injection improved body was taken out from the drum, and the improved diameter and shear elastic modulus were measured to evaluate the injection form.
For comparison, the injection material α and the injection material β were similarly injected.
＜使用材料＞
デンカ シリカボール主材：シリカ濃度40％の微粒子シリカ（デンカＳＦＰ２０Ｍ）スラリー、平均粒径0.6μｍ、分散剤を微粒子シリカに対して５％（固形分換算）添加
デンカ シリカボール硬化材：水酸化カルシウム濃度30％の微粒子水酸化カルシウムスラリー、平均粒径0.6μｍ、分散剤を微粒子シリカに対して５％（固形分換算）添加
分散剤 ：ナフタレンスルホン酸系市販品、液状、固形分濃度40％
注入材α ：市販超微粒子セメント、濃度10％
注入材β ：市販シリカコロイド系、濃度５％
試験用調整砂：44μｍ以下；5.0％、45〜74μｍ；16.6％、75〜105μｍ；32.6％、106〜149μｍ；36.9％、150〜211μｍ；8.9％（JIS Ｚ ２６０１による粒度測定結果）
<Materials used>
Denka silica ball main material: 40% silica concentration fine particle silica (Denka SFP20M) slurry, average particle size 0.6μm, and 5% of dispersant added to fine particle silica (solid content conversion) Denka Silica ball hardener: calcium hydroxide 30% concentration fine particle calcium hydroxide slurry, average particle size 0.6μm, dispersant 5% (converted to solid content) with respect to fine particle silica Dispersant: Naphthalenesulfonic acid commercial product, liquid, solid concentration 40%
Injection material α: Commercially available ultrafine cement, concentration 10%
Injection material β: commercially available silica colloid system, concentration 5%
Adjusted sand for testing: 44 μm or less; 5.0%, 45 to 74 μm; 16.6%, 75 to 105 μm; 32.6%, 106 to 149 μm; 36.9%, 150 to 211 μm; 8.9% (particle size measurement result according to JIS Z 2601)
＜評価方法＞
脈動率 ：注入速度の最大値と最小値の差を平均注入速度で割った値
改良径 ：球状の注入改良体を中心で切断し、直径の平均値を改良径とした。
せん断弾性係数：球状の注入供試体を切断し、地盤工学会基準ＪＧＳ０５４２〜ＪＧＳ０５４４に準じてせん断弾性係数（MN/m2）を求めた。
注入形態 ：球状の注入改良体を切断し、目視観察
<Evaluation method>
Pulsation rate: Value obtained by dividing the difference between the maximum value and minimum value of the injection rate by the average injection rate.
Shear elastic modulus: A spherical injection specimen was cut, and the shear elastic modulus (MN / m 2 ) was determined in accordance with JGS0542 to JGS0544.
Injection form: Cut a spherical injection improved body and visually observe it
表１から明らかなように、微粒子シリカ濃度や微粒子水酸化カルシウム濃度を最適化することにより、良好な改良径、最適なせん断弾性係数を示す注入改良体を得ることができる。 As can be seen from Table 1, by optimizing the fine particle silica concentration and the fine particle calcium hydroxide concentration, it is possible to obtain an improved injection body having a good improved diameter and an optimum shear modulus.
実験例２
微粒子シリカ１％、微粒子水酸化カルシウム１％の配合になる注入材を調製し、表２に示す注入圧力、注入速度、及び脈動率で注入したこと以外は、実験例１と同様に行った。結果を表２に併記する。
Experimental example 2
An injection material containing 1% fine particle silica and 1% fine particle calcium hydroxide was prepared, and the same procedure as in Experimental Example 1 was performed except that the injection material was injected at the injection pressure, injection rate, and pulsation rate shown in Table 2. The results are also shown in Table 2.
表２から明らかなように、注入圧力、注入速度、及び脈動率を最適化することにより、良好な改良径、最適なせん断弾性係数を示す注入改良体を得ることができる。 As is apparent from Table 2, by optimizing the injection pressure, the injection speed, and the pulsation rate, it is possible to obtain an injection improved body having a good improved diameter and an optimal shear modulus.
実験例３
実験例１の実験No.1- 4の配合を用い、実験例１の注入条件で、電気化学工業株式会社千葉工場内の、シルト分を45％含有する砂質地盤で、超多点注入工法による本注入を行った。
注入一カ月後に掘削し、注入改良体を確認したところ、注入材は全体にわたって浸透注入しており、切り出した注入改良体のせん断弾性係数は130〜460MN/m2であった。
Experimental example 3
Using the formulation of Experiment No.1-4 in Experiment Example 1, under the injection conditions of Experiment Example 1, in the sandy ground containing 45% silt in Electrochemical Industry Co., Ltd. Chiba Factory, super multi-point injection method This injection was performed.
One month after the injection, the excavation improvement body was confirmed by excavation, and the injection material was permeated throughout, and the shear elasticity coefficient of the cut out injection improvement body was 130 to 460 MN / m 2 .
本発明の注入工法は、用途は特に限定しないが、シルト及び／又は砂質地盤に浸透注入可能である特徴を生かし、液状化対策として用いることが好ましい。 The application method of the injection method of the present invention is not particularly limited, but it is preferably used as a countermeasure for liquefaction, taking advantage of the feature that it can be infiltrated into silt and / or sandy ground.
Claims (3)
The ground injection method according to claim 1 or 2 , wherein the ground injection method is used as a countermeasure against liquefaction.
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