JP6466615B2 - Solidification material for ground injection - Google Patents
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本発明は、地盤改良、液状化現象の防止、耐震補強等の幅広い用途に有用な地盤注入用固結材に関し、特にコロイダルシリカがシリカ含有地熱水由来のシリカを含有する、環境に優しくエコノミーな地盤注入用固結材に関する。 The present invention relates to a solid injection material useful for a wide range of applications such as ground improvement, prevention of liquefaction phenomenon, seismic reinforcement, and the like. Particularly, colloidal silica contains silica derived from silica-containing geothermal water. The present invention relates to a consolidation material for ground injection.
従来、コロイダルシリカ及び珪酸ソーダを含有する地盤注入用固結材は知られている。例えば、特許文献１の請求項１には、「コロイダルシリカと、水ガラス（珪酸ソーダ）とを含み、地盤への注入前にはそれ自体でゲル化しないアルカリ性シリカ溶液からなる地盤注入用固結材。」が記載されている。 Conventionally, a ground injection consolidation material containing colloidal silica and sodium silicate has been known. For example, in claim 1 of Patent Document 1, “consolidation for ground injection made of an alkaline silica solution containing colloidal silica and water glass (sodium silicate) and which does not gel by itself before being injected into the ground. Material ".
上記特許文献１には、コロイダルシリカと水ガラスの混合物（アルカリ性シリカ溶液）に反応剤として硫酸、リン酸等の酸性反応剤を添加し、液状化防止用の注入用固結材として使用できることが記載されている。この点について、特許文献１の［0029］段落には「例えば、アルカリ性シリカ溶液に酸性反応剤を添加して該溶液を酸性〜中性領域に調整して所定のゲル化時間を有するグラウトとすることができる。」と記載されている。 In Patent Document 1, an acidic reactant such as sulfuric acid or phosphoric acid is added as a reactant to a mixture of colloidal silica and water glass (alkaline silica solution), and can be used as a solidification material for injection for preventing liquefaction. Have been described. In this regard, paragraph [0029] of Patent Document 1 states that “for example, an acidic reactant is added to an alkaline silica solution to adjust the solution to an acidic to neutral region to obtain a grout having a predetermined gelation time. Is possible. "
従来の地盤注入用固結材に含まれるコロイダルシリカは、珪酸ソーダをイオン交換して製造するため、ナトリウム、中和後の芒硝（硫酸ナトリウム１０水和物）などの廃棄物が大量に副生するという問題がある。また、金属珪素（Ｓｉ）から製造する方法もあるが、製造時に水素が発生し、安全管理の点から商業ベースの製造ではコスト的に不利であり、前者の製法が主流である。 Colloidal silica contained in conventional consolidation materials for ground injection is produced by ion-exchange of sodium silicate, so that a large amount of waste such as sodium and neutralized sodium sulfate (sodium sulfate decahydrate) is produced as a by-product. There is a problem of doing. In addition, there is a method of manufacturing from metal silicon (Si), but hydrogen is generated at the time of manufacturing, which is disadvantageous in terms of cost in terms of safety management, and the former manufacturing method is mainstream.
このような廃棄物を大量に副生することなく、コスト的にも有利にコロイダルシリカを調製することができれば、環境に優しくエコノミーな地盤注入用固結材が得られると考えられるが、未だそのような要求を満足する製品は得られていない。 If colloidal silica can be prepared in a cost-effective manner without generating a large amount of such waste, it is thought that an environment-friendly and economical cementing material for ground injection can be obtained. No product that satisfies these requirements has been obtained.
よって、本発明は、良好な固結強度を有し、従来品に比して環境に優しくエコノミーな地盤注入用固結材を提供することを主な目的とする。 Therefore, the main object of the present invention is to provide a ground-injection consolidation material that has good consolidation strength and is environmentally friendly and economical as compared with conventional products.
本発明者は、上記目的を達成すべく鋭意研究を重ねた結果、地盤注入用固結材の調製に使用するコロイダルシリカに含まれるシリカとして特定のシリカを用いる場合には、上記目的を達成できることを見出し、本発明を完成するに至った。 As a result of intensive studies to achieve the above object, the present inventor can achieve the above object when using a specific silica as the silica contained in the colloidal silica used for the preparation of the consolidated material for ground injection. As a result, the present invention has been completed.
即ち、本発明は、下記の地盤注入用固結材に関する。
１．珪酸ソーダ、コロイダルシリカ及び酸成分を含有する地盤注入用固結材であって、
（１）前記コロイダルシリカは、シリカ含有地熱水由来のシリカを含有し、
（２）前記シリカ含有地熱水由来のシリカの動的光散乱法により求めた体積分布の尖度が０．０〜６．０の範囲である、
ことを特徴とする地盤注入用固結材。
２．前記酸成分は、硫酸、リン酸及び有機酸からなる群から選択される少なくとも一種である、上記項１に記載の地盤注入用固結材。
３．前記シリカ含有地熱水由来のシリカの平均粒子径は１０〜２０ｎｍである、上記項１又は２に記載の地盤注入用固結材。
４．前記珪酸ソーダは、ＳｉＯ２／Ｎａ２Ｏで表されるモル比が３〜５であり、且つ、ＳｉＯ２濃度が１０〜３０質量％である、上記項１〜３のいずれかに記載の地盤注入用固結材。
５．前記コロイダルシリカは、ＳｉＯ２濃度が２０〜５０質量％である、上記項１〜４のいずれかに記載の地盤注入用固結材。
That is, the present invention relates to the following consolidation material for ground injection.
1. A cement for ground injection containing sodium silicate, colloidal silica and an acid component,
(1) the colloidal silica contains silica from silica-containing geothermal water,
(2) The kurtosis of the volume distribution determined by the dynamic light scattering method of silica derived from the silica-containing geothermal water is in the range of 0.0 to 6.0.
A consolidation material for ground injection characterized by this.
2. Item 2. The consolidation material for ground injection according to Item 1, wherein the acid component is at least one selected from the group consisting of sulfuric acid, phosphoric acid, and organic acids.
3. Item 3. The consolidation material for ground injection according to Item 1 or 2, wherein the silica-containing geothermal water-derived silica has an average particle size of 10 to 20 nm.
4 . The ground according to any one of Items 1 to 3 , wherein the sodium silicate has a molar ratio represented by SiO 2 / Na 2 O of 3 to 5 and a SiO 2 concentration of 10 to 30% by mass. Solidified material for injection.
5 . The colloidal silica, SiO 2 concentration of 20 to 50 wt%, ground injection caking material according to any one of claim 1-4.
本発明の地盤注入用固結材は、珪酸ソーダ、コロイダルシリカ及び酸成分を含有する地盤注入用固結材であって、当該コロイダルシリカはシリカ含有地熱水由来のシリカを含有することにより、従来品に比して環境に優しくエコノミーである。特にシリカ含有地熱水由来のシリカは、地熱発電所の生産井から噴出する多量の地熱水中のシリカを限外濾過で濾過することにより簡便に得ることができるため、従来品のような大量の廃棄物を発生させないばかりか、むしろ天然資源を有効利用するものである。また、地熱水中のシリカを濾過により回収することにより、地熱発電所の地熱水配管において熱水が冷却された際に析出するシリカを含むスケールの付着を抑制できる点でも多大な利点がある。また、本発明の地盤注入用固結材を用いた固化体は、従来品と同等の良好な一軸圧縮強さを発揮するとともに従来品よりも顕著に大きい三軸強度（粘着力）を有しており、各種用途に幅広く適用することができる。 The ground injection consolidation material of the present invention is a ground injection consolidation material containing sodium silicate, colloidal silica and an acid component, and the colloidal silica contains silica derived from silica-containing geothermal water, Compared to conventional products, it is eco-friendly and eco-friendly. In particular, silica derived from geothermal water containing silica can be easily obtained by filtering the silica in a large amount of geothermal water ejected from the production well of the geothermal power plant by ultrafiltration. Not only does it not generate waste, but rather uses natural resources effectively. In addition, by collecting silica in geothermal water by filtration, there is a great advantage in that adhesion of scale containing silica that precipitates when hot water is cooled in the geothermal water piping of the geothermal power plant can be suppressed. In addition, the solidified body using the ground injection consolidation material of the present invention exhibits a good uniaxial compressive strength equivalent to that of the conventional product, and has a triaxial strength (adhesive strength) that is significantly larger than that of the conventional product. It can be widely applied to various uses.
以下、本発明の地盤注入用固結材について詳細に説明する。 Hereinafter, the ground injection consolidation material of the present invention will be described in detail.
本発明の地盤注入用固結材は、珪酸ソーダ、コロイダルシリカ及び酸成分を含有する地盤注入用固結材であって、当該コロイダルシリカは、シリカ含有地熱水由来のシリカを含有することを特徴とする。 The consolidation material for ground injection according to the present invention is a solid material for ground injection containing sodium silicate, colloidal silica and an acid component, and the colloidal silica contains silica derived from silica-containing geothermal water. Features.
上記特徴を有する本発明の地盤注入用固結材は、当該コロイダルシリカがシリカ含有地熱水由来のシリカを含有することにより、従来品のようにコロイダルシリカの調製に際し大量の廃棄物を発生させないばかりか、むしろ天然資源を有効利用するものであり、従来品に比して環境に優しくエコノミーである。 The consolidation material for ground injection according to the present invention having the above characteristics does not generate a large amount of waste in the preparation of colloidal silica unlike conventional products, because the colloidal silica contains silica derived from silica-containing geothermal water. In addition, it effectively uses natural resources and is environmentally friendly and economical compared to conventional products.
本発明の地盤注入用固結材は、コロイダルシリカに含まれるシリカとしてシリカ含有地熱水由来のシリカを含有する限り、その他の構成は限定的ではなく、珪酸ソーダ、酸成分等については従来の地盤注入用固結材に使用しているものが幅広く使用できる。 As long as the solid injection material for ground injection of the present invention contains silica derived from silica-containing geothermal water as silica contained in colloidal silica, other configurations are not limited, and sodium silicate, acid components, etc. are conventional. A wide range of materials can be used that are used for consolidation materials for ground injection.
珪酸ソーダとしては、市販品やそれに水を加えて希釈した希釈溶液を使用できる。 As sodium silicate, a commercially available product or a diluted solution diluted with water can be used.
珪酸ソーダのモル比（ＳｉＯ２／Ｎａ２Ｏ）は限定されないが、３〜５程度が好ましく、汎用の珪酸ソーダが使えるため、３．１〜３．８程度がより好ましい。 The molar ratio of sodium silicate (SiO 2 / Na 2 O) is not limited, but is preferably about 3 to 5, and more preferably about 3.1 to 3.8 because general-purpose sodium silicate can be used.
珪酸ソーダに含まれるシリカ濃度（ＳｉＯ２濃度）としては、１０〜３０質量％程度が好ましく、２０〜３０質量％程度がより好ましい。 The silica concentration (SiO 2 concentration) contained in the sodium silicate is preferably about 10 to 30% by mass, and more preferably about 20 to 30% by mass.
珪酸ソーダとしては、ＪＩＳ Ｋ１４０８に示されている１号〜３号珪酸ソーダに加えて、モル比（ＳｉＯ２／Ｎａ２Ｏ）３．１〜４程度の工業品が知られている。その中でも、高モル比の珪酸ソーダを用いることにより、部分ゲルの発生をより抑制することができ、得られる地盤注入用固結材の固結後の強度向上及び収縮抑制の効果が得られ易い。本発明では高モル比の珪酸ソーダの中でも、モル比が３．７、ＳｉＯ２濃度が２５．６質量％である珪酸ソーダを使用することが好ましい。なお、モル比が３．５〜３．８、ＳｉＯ２濃度が２４〜３０質量％の珪酸ソーダを用いる場合には、上記珪酸ソーダと同様の良好な効果が得られ易い。 As sodium silicate, in addition to No. 1 to No. 3 sodium silicate shown in JIS K1408, industrial products having a molar ratio (SiO 2 / Na 2 O) of about 3.1 to 4 are known. Among them, by using sodium silicate having a high molar ratio, the generation of partial gel can be further suppressed, and the effect of improving strength and suppressing shrinkage after consolidation of the obtained consolidated material for ground injection can be easily obtained. . In the present invention, it is preferable to use sodium silicate having a molar ratio of 3.7 and a SiO 2 concentration of 25.6% by mass among the high molar ratio sodium silicate. The molar ratio of 3.5 to 3.8, if the SiO 2 concentration is used 24-30% by weight of the sodium silicate is likely good effect similar to the above sodium silicate can be obtained.
コロイダルシリカは、コロイド状の性状を示し、それ単独では長期的にゲル化しない安定な物質である。本発明では、当該コロイダルシリカとして、シリカ含有地熱水由来のシリカを含有するものを用いる。 Colloidal silica is a stable substance that exhibits colloidal properties and does not gel on a long-term basis. In this invention, what contains the silica derived from a silica containing geothermal water is used as the said colloidal silica.
シリカ含有地熱水由来のシリカ（ＳｉＯ２）の平均粒子径としては、１０〜２０ｎｍが好ましく、１０〜１５ｎｍがより好ましい。なお、本明細書に記載の平均粒子径は、ＳＴＥＭによる観察により測定した値である。但し、ＳＴＥＭにより測定困難な微粒子はＢＥＴ法、シアーズ滴定法又は動的光散乱法による測定値とし、測定法を明記する。また、シリカ含有地熱水由来のシリカ（ＳｉＯ２）の粒子径の体積分布は＜１００ｎｍにわたり広く分布している。幅広い体積分布の尖度は０．０〜６．０の範囲であることが好ましく、２．０〜４．０の範囲であることがより好ましい。この粒子径の体積分布及び尖度の点でシリカ含有地熱水由来のシリカは、水ガラスをイオン交換することにより得られる従来品のコロイダルシリカとは明確に区別される。 The average particle diameter of the silica-containing geothermal water from silica (SiO 2), 10~20nm preferably, 10 to 15 nm is more preferable. In addition, the average particle diameter described in this specification is a value measured by observation with STEM. However, fine particles that are difficult to measure by STEM are measured by the BET method, Sears titration method or dynamic light scattering method, and the measurement method is specified. In addition, the volume distribution of the particle diameter of silica (SiO 2 ) derived from silica-containing geothermal water is widely distributed over <100 nm. The kurtosis of a wide volume distribution is preferably in the range of 0.0 to 6.0, and more preferably in the range of 2.0 to 4.0. Silica derived from silica-containing geothermal water is clearly distinguished from conventional colloidal silica obtained by ion exchange of water glass in terms of volume distribution and kurtosis.
シリカ含有地熱水由来のシリカは、地熱流体である地熱水に含まれるシリカを回収及び精製することにより得られるものが例示でき、具体的には、地熱発電所の生産井から噴出する多量の地熱水中のシリカを限外濾過で濾過することにより簡便に得ることができる。 The silica-derived geothermal water-derived silica can be exemplified by those obtained by recovering and purifying silica contained in the geothermal water, which is a geothermal fluid, and specifically, a large amount ejected from the production well of the geothermal power plant The silica in the geothermal water can be easily obtained by filtering by ultrafiltration.
本発明では、例えば、上記手法により得られたシリカ含有地熱水由来のシリカに水などの分散媒を混合することによりコロイダルシリカを調製してもよく、地熱発電所の生産井から噴出するシリカを含む多量の地熱水を回収し、それを粒子成長及び濃縮し、粒径及び固形分濃度を調整することによりコロイダルシリカを調製してもよい。 In the present invention, for example, colloidal silica may be prepared by mixing a dispersion medium such as water with silica derived from silica-containing geothermal water obtained by the above method, and silica ejected from a production well of a geothermal power plant Colloidal silica may be prepared by collecting a large amount of geothermal water containing, growing and concentrating it, and adjusting the particle size and solid content concentration.
シリカ含有地熱水由来のシリカを含有するコロイダルシリカ（又は類似品）の公知品としては、例えば、商品名「ＧｅｏＳｏｌ」（Geo40 Limited製）がある。このように、地熱流体である地熱水に含まれる天然資源のシリカを回収して地盤注入用固結材の材料とし、施工現場で地盤に戻すことにより地盤改良などを行う点で、本発明の地盤注入用固結材は非常に環境に優しくエコノミーである。 As a known product of colloidal silica (or similar product) containing silica derived from silica-containing geothermal water, for example, there is a trade name “GeoSol” (manufactured by Geo40 Limited). In this way, the present invention is such that the silica of natural resources contained in geothermal water, which is a geothermal fluid, is recovered and used as a material for consolidation material for ground injection, and the ground is improved by returning it to the ground at the construction site. The consolidation material for ground injection is very environmentally friendly and economical.
コロイダルシリカに含まれるＳｉＯ２濃度としては限定的ではないが、２０〜５０質量％が好ましく、２０〜４０質量％がより好ましい。 Not critical as SiO 2 concentration in the colloidal silica is preferably from 20 to 50 wt%, more preferably 20 to 40 wt%.
酸成分としては限定されず、例えば、塩酸、硫酸、硝酸、リン酸、その他の鉱酸等、クエン酸、グリコール酸、リンゴ酸、酒石酸、その他の有機酸等を幅広く使用することができるが、その中でも硫酸、リン酸及び有機酸の少なくとも一種が好ましい。これらの酸は単独で使用してもよく、複数種類を混合して使用することもできる。これらの酸は、市販の酸原液又はそれを水希釈した酸水溶液がそのまま使用できる。 The acid component is not limited and, for example, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, other mineral acids, citric acid, glycolic acid, malic acid, tartaric acid, other organic acids, etc. can be widely used. Among these, at least one of sulfuric acid, phosphoric acid and organic acid is preferable. These acids may be used alone or in combination of two or more. As these acids, a commercially available acid stock solution or an acid aqueous solution obtained by diluting it with water can be used as it is.
上記酸成分及び水の混合割合は、地盤注入用固結材の所望のＳｉＯ２含有量、ｐＨ及びゲルタイムに応じて適宜設定することができる。本発明では、地盤注入用固結材のＳｉＯ２含有量は限定的ではないが、２〜１５質量％が好ましく、３〜１２質量％がより好ましい。また、ｐＨとゲルタイムは関連しており、地盤注入用固結材の用途が液状化防止用である場合には、ｐＨ２〜４程度、ゲルタイム１０時間以上に設定することが好ましい。他方、地盤注入用固結材が瞬結〜緩結タイプ（ゲルタイム１０秒〜１時間程度）の場合には、ｐＨ４〜８程度に設定することが好ましい。なお、当該ゲルタイムは、室温下、５００ｍｌビーカーに地盤注入用固結材１５０ｍｌ及び３８．４ｍｍ×φ８ｍｍ回転子を入れて、初速４０ｒｐｍで回転させ、回転が停止した時間を意味する。 The mixing ratio of the acid component and water can be appropriately set according to the desired SiO 2 content, pH, and gel time of the consolidation material for ground injection. In the present invention, the content of SiO 2 in the consolidation material for ground injection is not limited, but is preferably 2 to 15% by mass, more preferably 3 to 12% by mass. Moreover, pH and gel time are related, and when the use of the consolidation agent for ground injection is for liquefaction prevention, it is preferable to set pH to about 2 to 4 and gel time of 10 hours or more. On the other hand, it is preferable to set the pH to about 4 to 8 when the solidification material for ground injection is a quick setting to slow setting type (gel time of about 10 seconds to about 1 hour). In addition, the said gel time means the time which rotation stopped at the initial speed of 40 rpm by putting the solid injection | pouring material 150ml and a 38.4mm x (phi) 8mm rotor in a 500ml beaker at room temperature.
よって、水の混合割合は地盤注入用固結材のＳｉＯ２含有量の調整の点で設定し、酸成分の混合割合はｐＨ及びゲルタイムの調整の点で設定すればよい。なお、水は酸成分の希釈のみならず、前述の珪酸ソーダ及び／又はコロイダルシリカの希釈にも使用できる。 Therefore, the mixing ratio of water may be set in terms of adjusting the SiO 2 content of the ground injection consolidation material, and the mixing ratio of the acid component may be set in terms of adjusting pH and gel time. Water can be used not only for diluting the acid component but also for diluting the aforementioned sodium silicate and / or colloidal silica.
本発明の地盤注入用固結材は、従来から地盤注入用固結材の技術分野で公知の添加剤を適宜含有することができる。添加剤の種類及び含有量は常法に従って選択できる。 The consolidation material for ground injection according to the present invention can appropriately contain conventionally known additives in the technical field of consolidation materials for ground injection. The kind and content of the additive can be selected according to a conventional method.
本発明の地盤注入用固結材の粘度は限定されないが、１〜１０ｍＰａ・ｓ以下が好ましく、４ｍＰａ・ｓ以下程度がより好ましい。 The viscosity of the consolidation material for ground injection of the present invention is not limited, but is preferably 1 to 10 mPa · s or less, and more preferably about 4 mPa · s or less.
本発明の地盤注入用固結材は、地盤改良（地盤補強も含む）、液状化現象の防止、耐震補強等の幅広い用途に適用することができる。また、特に地盤注入用固結材のＳｉＯ２濃度が１０質量％を超える場合には大きな固結強度を発揮でき、液状化現象の防止の用途よりも高強度を要求される既存の岸壁、護岸又は構造物の耐震補強及び／又は周囲の地盤改良（特に海辺地域などの海水の影響を受ける砂質地盤）に適用することもできる。 The consolidation material for ground injection according to the present invention can be applied to a wide range of uses such as ground improvement (including ground reinforcement), prevention of liquefaction phenomenon, and seismic reinforcement. In addition, especially when the SiO 2 concentration of the consolidation material for ground injection exceeds 10% by mass, it can exhibit a large consolidation strength, and existing quay walls and revetments that require higher strength than applications for preventing liquefaction phenomena. Alternatively, it can be applied to seismic reinforcement of structures and / or surrounding ground improvement (especially sandy ground affected by seawater such as seaside areas).
より具体的には、既存の岸壁、護岸又は構造物（タンク、建造物、橋脚、滑走路等）の耐震補強（レベル２地震動対応）、岸壁増深時の岸壁前面の地盤改良、岸壁背面地盤の土圧低減、既存の構造物の下部地盤の支持力増加などの用途に適用できる。なお、「レベル２地震動」とは、土木学会が定義する構造物の耐震設計に用いる入力地震動であり、「現在から将来にわたって当該地点で考えられる最大級の強さをもつ地震動」を意味する。 More specifically, seismic reinforcement of existing quay, revetment or structure (tank, building, pier, runway, etc.) It can be used for applications such as reducing earth pressure and increasing the bearing capacity of the lower ground of existing structures. “Level 2 ground motion” is input ground motion used for seismic design of structures defined by the Japan Society of Civil Engineers, and means “seismic motion having the maximum strength that can be considered at this point from the present to the future”.
本発明の地盤注入用固結材の製造方法は限定的ではないが、例えば、調製用容器に水の一部を入れておき、当該水を撹拌しながら酸成分、珪酸ソーダ及びコロイダルシリカを順不同で添加・混合することにより調製することが好ましい。このような混合方法を採用することにより、各成分を効率的に混合することができるとともに酸成分の供給による調製用容器の腐食等の発生を効果的に抑制することができる。 The method for producing the ground injection consolidated material of the present invention is not limited.For example, a part of water is placed in a preparation container, and the acid component, sodium silicate and colloidal silica are mixed in any order while stirring the water. It is preferable to prepare by adding and mixing. By adopting such a mixing method, it is possible to efficiently mix the components and to effectively suppress the occurrence of corrosion of the preparation container due to the supply of the acid component.
以下に実施例、比較例及び試験例を示して本発明を具体的に説明する。但し、本発明は実施例に限定されない。 The present invention will be specifically described below with reference to examples, comparative examples and test examples. However, the present invention is not limited to the examples.
実施例１及び比較例１（地盤注入用固結材の調製）
下記表１に示す配合でＡ液、Ｂ液及びＣ液を混合して実施例１及び比較例１の地盤注入用固結材（全シリカ濃度は１０質量％）を調製した。実施例１はコロイダルシリカとして、シリカ含有地熱水由来のシリカを含有するコロイダルシリカ類似品（ＧｅｏＳｏｌ、シリカ濃度３０質量％、Geo40 Limited製）を使用し、比較例１はコロイダルシリカとして、水ガラスをイオン交換することにより得られる従来品のコロイダルシリカ（シリカ濃度４０質量％）を使用して地盤注入用固結材を調製した。以下、各コロイダルシリカは「ＧｅｏＳｏｌ」及び「従来品のコロイダルシリカ」と略記する。
Example 1 and Comparative Example 1 (Preparation of consolidation material for ground injection)
Liquid A, liquid B and liquid C were mixed with the formulation shown in Table 1 below to prepare ground injection solidifying materials (total silica concentration of 10% by mass) in Example 1 and Comparative Example 1. Example 1 uses a colloidal silica analog (GeoSol, silica concentration 30 mass%, manufactured by Geo40 Limited) containing silica derived from silica-containing geothermal water as colloidal silica, and Comparative Example 1 uses water glass as colloidal silica. Using a conventional colloidal silica (silica concentration of 40% by mass) obtained by ion exchange, a solidified material for ground injection was prepared. Hereinafter, each colloidal silica is abbreviated as “GeoSol” and “conventional colloidal silica”.
上記で使用した珪酸ソーダの物性は次の通りである。 The physical properties of the sodium silicate used above are as follows.
ＳｉＯ２：２５．６質量％、Ｎａ２Ｏ：７．１質量％、モル比：３．７
上記で使用したＧｅｏＳｏｌ及び従来品のコロイダルシリカについて、粒径測定システム（大塚電子製：ＥＬＳＺ−２０００）を用いて各液中のシリカ粒子の体積分布を動的光散乱法により測定した。
SiO 2 : 25.6% by mass, Na 2 O: 7.1% by mass, molar ratio: 3.7
About the GeoSol used above and the conventional colloidal silica, the volume distribution of the silica particles in each liquid was measured by a dynamic light scattering method using a particle size measurement system (manufactured by Otsuka Electronics: ELSZ-2000).
体積分布（粒子径の体積分布及び累積頻度分布）の測定結果を図１に示す。また、図１のヒストグラムから求めた体積分布の尖度を下記表２に示す。 The measurement results of the volume distribution (volume distribution of particle diameter and cumulative frequency distribution) are shown in FIG. Further, the kurtosis of the volume distribution obtained from the histogram of FIG.
図１及び表２の結果から明らかなように、シリカ含有地熱水由来のシリカは、水ガラスをイオン交換することにより得られる従来品のコロイダルシリカと比べて幅広い体積分布を持つことが分かった。特に体積分布の鋭さを示す尖度については、シリカ含有地熱水由来のシリカは従来品のコロイダルシリカと比べて１／４程度であり、このことからもシリカ含有地熱水由来のシリカが幅広い体積分布を持つことが分かる。 As is apparent from the results of FIG. 1 and Table 2, it was found that silica derived from silica-containing geothermal water has a broad volume distribution compared to conventional colloidal silica obtained by ion exchange of water glass. . In particular, with regard to the kurtosis indicating the sharpness of the volume distribution, silica derived from silica-containing geothermal water is about ¼ compared to conventional colloidal silica, and from this, silica derived from silica-containing geothermal water is also wide. It can be seen that it has a volume distribution.
また、従来品のコロイダルシリカとＧｅｏＳｏｌとを走査型電子顕微鏡（ＳＥＭ；型番「ＳＵ８００」、株式会社日立製作所製）により観察した。具体的には、従来品のコロイダルシリカとＧｅｏＳｏｌのサンプルをＳＥＭのステージ上に滴下し、乾燥させて観察を行った。各観察像をそれぞれ図２（ａ）及び（ｂ）に示す。 Further, conventional colloidal silica and GeoSol were observed with a scanning electron microscope (SEM; model number “SU800”, manufactured by Hitachi, Ltd.). Specifically, a sample of conventional colloidal silica and GeoSol was dropped on a SEM stage, dried and observed. Each observation image is shown in FIGS. 2 (a) and 2 (b), respectively.
図２（ａ）の結果から分かるように、従来品のコロイダルシリカの乾燥物は球形の一次粒子が凝集した構造であり、粒子間の隙間も確認された。これは、体積分布が鋭い点で粒子径が揃っており、凝集すると粒子間の隙間が認められ易いからと考えられる。これに対して、図２（ｂ）の結果から分かるように、シリカ含有地熱水由来のシリカの乾燥物は一次粒子が密に充填されており、隙間は殆ど認められなかった。これは、体積分布が幅広い点で、凝集すると幅広い粒径の一次粒子が密に充填した凝集物が得られ易いからと考えられる。かかる密な凝集構造が、後記の優れた粘着力の発現に寄与すると考えられる。 As can be seen from the results in FIG. 2 (a), the dried product of the conventional colloidal silica has a structure in which spherical primary particles are aggregated, and gaps between the particles are also confirmed. This is presumably because the particle diameters are uniform at points where the volume distribution is sharp, and when the particles are aggregated, the gaps between the particles are easily recognized. On the other hand, as can be seen from the results of FIG. 2 (b), the dried silica product derived from the silica-containing geothermal water was packed with primary particles, and almost no gaps were observed. This is presumably because the volume distribution is wide, and when agglomerated, it is easy to obtain an agglomerate in which primary particles having a wide particle size are packed closely. Such a dense aggregate structure is considered to contribute to the development of the excellent adhesive force described later.
試験例１（実施例１及び比較例１の地盤注入用固結材を用いた供試体の固結強度）
実施例１及び比較例１で調製した地盤注入用固結材及び豊浦砂を用いて、内径５ｃｍ×高さ１０ｃｍ、相対密度５０％の供試体を作製した。この供試体の材齢１週間のサンドゲルの一軸圧縮強さを測定した。
Test Example 1 (Consolidation Strength of Specimen Using Ground Injection Consolidation Material of Example 1 and Comparative Example 1)
A specimen having an inner diameter of 5 cm, a height of 10 cm, and a relative density of 50% was prepared using the ground injection caking material and Toyoura sand prepared in Example 1 and Comparative Example 1. The uniaxial compressive strength of a sand gel with a material age of 1 week was measured.
供試体の作製方法及び一軸圧縮強さの測定方法は次の通りとした。
（１）円柱の型（内径５ｃｍ、高さ１０ｃｍ）からその円柱の体積を求める。
（２）豊浦砂を、上記体積に対して相対密度５０％になるように計量する。相対密度は砂の種類により異なり、相対密度１００％はその砂を限界まで密に詰めた状態、０％はできる限り緩く詰めた状態であり、５０％はその中間の状態である。
（３）上記円柱の型に地盤注入用固結材を入れ、そこに計量した豊浦砂が均一になるように流し込む。
（４）地盤注入用固結材がゲル化して材齢１週間となるまで静置して待つ。
（５）ゲル化した後、円柱を高さ１０ｃｍになるように整えて供試体とする。
（６）供試体を圧縮強さ測定機で圧縮し、供試体が壊れた時の一軸圧縮強さを測定する。一軸圧縮強さの単位は（圧力／単位面積）である。
The specimen preparation method and the uniaxial compressive strength measurement method were as follows.
(1) The volume of the cylinder is determined from the cylinder mold (inner diameter 5 cm, height 10 cm).
(2) Weigh Toyoura sand so that the relative density is 50% with respect to the volume. Relative density varies depending on the type of sand, with a relative density of 100% being packed as tightly as possible, 0% being packed as loosely as possible, and 50% being an intermediate state.
(3) Put the ground injection consolidation material into the above-mentioned cylindrical mold, and pour it into the measured Toyoura sand uniformly.
(4) Let stand and wait until the consolidated material for ground injection gels and becomes 1 week old.
(5) After gelation, the cylinder is adjusted to a height of 10 cm and used as a specimen.
(6) The specimen is compressed with a compressive strength measuring device, and the uniaxial compressive strength when the specimen is broken is measured. The unit of uniaxial compressive strength is (pressure / unit area).
強度測定結果を表３に示す。両者はほぼ同等であり、コロイダルシリカとしてシリカ含有地熱水由来のシリカを含有するコロイダルシリカを用いる場合でも、従来品のコロイダルシリカを用いる場合と同等の固結強度（一軸圧縮強さ）を発現することが分かった。 The strength measurement results are shown in Table 3. Both of them are almost the same, and even when colloidal silica containing silica derived from silica-containing geothermal water is used as colloidal silica, the same consolidation strength (uniaxial compressive strength) as when using conventional colloidal silica is exhibited. I found out that
実施例２及び比較例２、３（地盤注入用固結材の調製）
下記表４に示す配合でＡ液、Ｂ液及びＣ液を混合して実施例２及び比較例２、３の地盤注入用固結材（全シリカ濃度は７質量％）を調製した。実施例２はコロイダルシリカとして、シリカ含有地熱水由来のシリカを含有するコロイダルシリカ類似品（ＧｅｏＳｏｌ、シリカ濃度３０質量％、Geo40 Limited製）を使用し、比較例２はコロイダルシリカとして、水ガラスをイオン交換することにより得られる従来品のコロイダルシリカ（シリカ濃度４０質量％）を使用して地盤注入用固結材を調製した。前記同様、各コロイダルシリカは「ＧｅｏＳｏｌ」及び「従来品のコロイダルシリカ」と略記する。
Example 2 and Comparative Examples 2 and 3 (Preparation of consolidation material for ground injection)
Liquid A, liquid B and liquid C were mixed with the formulation shown in Table 4 below to prepare ground injecting solidified materials of Example 2 and Comparative Examples 2 and 3 (total silica concentration was 7% by mass). Example 2 uses a colloidal silica analog (GeoSol, silica concentration 30 mass%, manufactured by Geo40 Limited) containing silica derived from silica-containing geothermal water as colloidal silica, and Comparative Example 2 uses water glass as colloidal silica. Using a conventional colloidal silica (silica concentration of 40% by mass) obtained by ion exchange, a solidified material for ground injection was prepared. Like the above, each colloidal silica is abbreviated as “GeoSol” and “conventional colloidal silica”.
試験例２（実施例２及び比較例２、３の地盤注入用固結材を用いた供試体の三軸強度（ＣＤ）試験）
実施例２及び比較例２、３で調製した地盤注入用固結材及び豊浦砂を用いて、浸透注入法により内径５ｃｍ×高さ１０ｃｍ、相対密度５０％の供試体を作製した。具体的には、豊浦砂をモールドに充填後、炭酸ガス、水の順で流した後に地盤注入用固結材を通液し、脱型後、乾燥しないように湿潤状態で２８日間養生した。
Test Example 2 (Triaxial Strength (CD) Test of Specimen Using Ground Injection Solidifying Material of Example 2 and Comparative Examples 2 and 3)
A specimen having an inner diameter of 5 cm, a height of 10 cm, and a relative density of 50% was prepared by the osmotic injection method using the ground injection consolidation material and Toyoura sand prepared in Example 2 and Comparative Examples 2 and 3. Specifically, after filling the Toyoura sand into the mold, flowing carbon dioxide gas and water in that order, the ground filler was poured, and after demolding, it was cured in a wet state for 28 days so as not to dry.
三軸強度（ＣＤ）試験の条件を下記表５に示す。 The conditions of the triaxial strength (CD) test are shown in Table 5 below.
下記表６に三軸強度（ＣＤ）試験の結果を示す。 Table 6 below shows the results of the triaxial strength (CD) test.
地盤の強度ｑｕは、下記式（１）により、内部摩擦角φ（°）と粘着力ｃｄ（kN/m2）により付与される。 The ground strength q u is given by the internal friction angle φ (°) and the adhesive force c d (kN / m 2 ) according to the following formula (1).
ｃｄ＝ｑｕ／２×ｔａｎ（４５°−φ／２） （１）
ここで、内部摩擦角φに由来する強度は、剪断時に砂の粒子同士が擦れるときの摩擦により発現し、粘着力ｃｄは砂の粒子間に働く静電引力、付着力等により発現する。溶液型注入材を用いた薬液注入工法では砂の間隙をゲルで満たすことで付着力が高まり、粘着力が増加する。これによって改良地盤は強度発現するため、粘着力を検討することは固結材の性能を評価する上で重要であり、粘着力が大きいと地盤の強度が大きくなる。
c d = q u / 2 × tan (45 ° −φ / 2) (1)
Here, the strength derived from the internal friction angle phi, expressed by friction when the particles of the sand rubs during shear, adhesion c d is the electrostatic attraction acting between sand grains, expressed by adhesion or the like. In the chemical solution injection method using a solution type injection material, the adhesion force is increased and the adhesive force is increased by filling the gaps of the sand with gel. Since the improved ground develops strength by this, it is important to examine the adhesive strength in evaluating the performance of the consolidated material. If the adhesive strength is large, the strength of the ground increases.
表６の結果から明らかなように、実施例２で作製した供試体は、比較例２、３で作製した供試体と比べて粘着力が顕著に大きく、シリカ含有地熱水由来のシリカを用いることにより地盤改良により地盤の強度を大きく改善することができる。よって、シリカ含有地熱水由来のシリカは特に液状化対策に用いる地盤注入用固結材に含まれるシリカ成分として好適であることが分かる。 As is clear from the results in Table 6, the specimen prepared in Example 2 has significantly higher adhesive strength than the specimens prepared in Comparative Examples 2 and 3, and silica derived from silica-containing geothermal water is used. Therefore, the strength of the ground can be greatly improved by improving the ground. Therefore, it turns out that the silica derived from a silica containing geothermal water is suitable as a silica component contained in the solidification material for ground injection used especially for a liquefaction countermeasure.
Claims (5)
（１）前記コロイダルシリカは、シリカ含有地熱水由来のシリカを含有し、
（２）前記シリカ含有地熱水由来のシリカの動的光散乱法により求めた体積分布の尖度が０．０〜６．０の範囲である、
ことを特徴とする地盤注入用固結材。 A cement for ground injection containing sodium silicate, colloidal silica and an acid component,
(1) the colloidal silica contains silica from silica-containing geothermal water,
(2) The kurtosis of the volume distribution determined by the dynamic light scattering method of silica derived from the silica-containing geothermal water is in the range of 0.0 to 6.0.
A consolidation material for ground injection characterized by this.
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