JP7627182B2 - Method for manufacturing modified soil - Google Patents
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- JP7627182B2 JP7627182B2 JP2021111796A JP2021111796A JP7627182B2 JP 7627182 B2 JP7627182 B2 JP 7627182B2 JP 2021111796 A JP2021111796 A JP 2021111796A JP 2021111796 A JP2021111796 A JP 2021111796A JP 7627182 B2 JP7627182 B2 JP 7627182B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Description
本発明は、改質土壌の製造方法、盛土の構築方法、及び軟弱土壌用添加剤に関する。 The present invention relates to a method for producing modified soil, a method for constructing embankments, and an additive for soft soil.
土壌のうち、川や湖沼に堆積したヘドロ、高有機質土、腐植土、水害により生じた土砂、建設汚泥などの含水量が多いものは、いわゆる軟弱土壌として知られている。軟弱土壌は、一般に泥状で強度が極めて小さいため、そのままの状態では運搬や再利用が困難である。そこで、軟弱土壌の強度を向上させて取り扱い性を向上させるために、固化材を用いた固化処理を行うことが知られている。固化材としては、従来、セメント、生石灰、消石灰などの無機材料が用いられているが、高分子化合物などの有機材料を用いることも提案されている。 Soils with a high water content, such as sludge accumulated in rivers and lakes, highly organic soil, humus soil, soil and sand generated by flood damage, and construction sludge, are known as soft soils. Soft soils are generally muddy and have very little strength, making them difficult to transport or reuse in their original state. Therefore, it is known that solidification treatment using solidification materials can be carried out to improve the strength of soft soil and make it easier to handle. Traditionally, inorganic materials such as cement, quicklime, and hydrated lime have been used as solidification materials, but the use of organic materials such as polymer compounds has also been proposed.
特許文献１には、含水率が広範囲の含水排土に適用可能で、短時間に改質でき、しかも改質された被処理土に振動を加えても元の性状に戻らない含水排土の改質方法として、含水排土に吸水性樹脂と水溶性高分子化合物とを添加する含水排土の改質方法が記載されている。そして、実施例では含水率６５％の排土に吸水性樹脂としてポリアクリル酸ナトリウム架橋体とジメチルアミノメタクリレートのメチルクロライド化合物を用いて改質された排土の浸出水量が少なく及びフロー値が小さいことが開示されている。 Patent Document 1 describes a method for modifying wet soil by adding a water-absorbent resin and a water-soluble polymer compound to the wet soil, which is applicable to wet soil with a wide range of moisture content, can be modified in a short time, and does not return to its original state even when the modified soil is subjected to vibration. In the examples, it is disclosed that the amount of leachate and the flow value of the soil modified using a cross-linked sodium polyacrylate and a methyl chloride compound of dimethylamino methacrylate as a water-absorbent resin for soil with a moisture content of 65% are small.
特許文献２には、石灰系硬化剤を用いずに環境に適合し、土壌強度が得られる含水土壌硬化剤として、吸水性繊維物質と親水性高分子化合物を主成分とする含水土壌の硬化剤が記載されている。また、含水土壌を硬化、安定化させる従来の技術として、吸水性高分子化合物、更には石灰と吸水性高分子化合物との複合物などが硬化剤として使用されていることが開示されている。 Patent Document 2 describes a hardener for moist soil that is made primarily of water-absorbent fibrous material and a hydrophilic polymeric compound, as a moist soil hardener that is environmentally friendly and can obtain soil strength without using lime-based hardeners. It also discloses that, as a conventional technique for hardening and stabilizing moist soil, water-absorbent polymeric compounds and even composites of lime and water-absorbent polymeric compounds are used as hardeners.
特許文献３には、高含水土壌を造粒して、土壌造粒物を調製するための土壌造粒用添加材であって、土壌造粒物の運搬や再利用等の際の取り扱いが容易であり、かつ、土壌造粒物のｐＨを、環境基準値である５．８～８．６の範囲内に収めることのできる土壌造粒用添加材として、９０％重量累積粒径が４００μｍ以下であるノニオン性高分子凝集剤を含む土壌造粒用添加材が記載されている。 Patent Document 3 describes a soil granulation additive for granulating high-moisture soil to prepare soil granules, which is easy to handle when transporting or reusing the soil granules and can keep the pH of the soil granules within the environmental standard range of 5.8 to 8.6, and contains a nonionic polymer flocculant with a 90% cumulative particle size by weight of 400 μm or less.
軟弱土壌を固化させる技術は、従来、種々提案されているが、含水比がより高い、例えば含水比が１００質量％以上の軟弱土壌は固化させることが極めて困難であり、仮に固化できたとしても粘性を持つ粗大な塊状物として得られることが多く、取り扱い性のよい、さらさらした粒状の改質土壌として得ることはできなかった。また、軟弱土壌を固化させた土を、例えば盛土などとして再利用する場合は、使用形態において高い強度を示すことが望まれる。 Various techniques have been proposed to solidify soft soil, but it is extremely difficult to solidify soft soil with a higher moisture content, for example, a moisture content of 100% by mass or more. Even if it is possible to solidify the soil, it is often obtained as coarse, viscous lumps, and it is not possible to obtain a loose, granular, improved soil that is easy to handle. Furthermore, when solidifying soft soil to be reused, for example as embankment, it is desirable for the soil to exhibit high strength in the form of use.
本発明は、含水比が高い軟弱土壌から、取り扱い性がよく、且つ再利用時の強度が高い改質土壌を得ることができる改質土壌の製造方法を提供する。 The present invention provides a method for producing modified soil that can produce modified soil that is easy to handle and has high strength when reused from soft soil with a high moisture content.
本発明は、含水比が１００質量％以上の軟弱土壌に、水による膨潤時のタッピングフロー値が９０ｍｍ以下の吸水性粒子（Ａ）と生石灰（Ｂ）とを添加する、改質土壌の製造方法に関する。 The present invention relates to a method for producing improved soil, in which water-absorbing particles (A) having a tapping flow value of 90 mm or less when swollen with water and quicklime (B) are added to soft soil having a moisture content of 100% by mass or more.
また、本発明は、含水比が１００質量％以上の軟弱土壌に、水による膨潤時のタッピングフロー値が９０ｍｍ以下の吸水性粒子（Ａ）と生石灰（Ｂ）とを添加して、改質土壌を得、得られた改質土壌を用いて盛土を構築する、盛土の施工方法に関する。 The present invention also relates to a method for constructing embankments, in which water-absorbing particles (A) having a tapping flow value of 90 mm or less when swollen with water and quicklime (B) are added to soft soil having a water content of 100% or more by mass to obtain modified soil, and the modified soil is used to construct an embankment.
また、本発明は、水による膨潤時のタッピングフロー値が９０ｍｍ以下の吸水性粒子（Ａ）と、生石灰（Ｂ）とを含有する、軟弱土壌用添加剤に関する。 The present invention also relates to an additive for soft soil that contains water-absorbing particles (A) that have a tapping flow value of 90 mm or less when swollen with water, and quicklime (B).
本発明によれば、含水比が高い軟弱土壌から、取り扱い性がよく、且つ再利用時の強度が高い改質土壌を得ることができる改質土壌の製造方法が提供される。本発明により製造された改質土壌を用いて強度に優れた盛土を構築することができる。 The present invention provides a method for producing modified soil that can produce modified soil that is easy to handle and has high strength when reused from soft soil with a high moisture content. The modified soil produced by the present invention can be used to build embankments with excellent strength.
（Ａ）成分のタッピングフロー値は、水で膨潤させた吸水性粒子の流動性を示す指標であり、この指標は吸水性粒子の架橋度と相関があると考えられ、タッピングフロー値が小さいほど吸水性粒子の架橋度が大きいと推定される。吸水性粒子の架橋度が大きいことにより、軟弱土壌中の水分を吸収しても吸水性粒子が膨潤しにくくなる。本発明では、特定のタッピングフロー値の吸水性粒子を用いることにより、軟弱土壌中の水分を減少させつつ吸水後の粒子による改質土壌の粘性の増加が抑制されるため、突き固め性が向上し、養生後に強度を発現すると考えられる。また、（Ｂ）成分の生石灰は水と反応し水酸化カルシウムとなるが、その際に大きく発熱する。（Ｂ）成分は、化学反応としての水の取り込み及び発熱による水の蒸散促進によって、含水土中の水分量を減少させ、（Ａ）成分により向上した突き固め性を更に相乗的に向上させると考えられる。 The tapping flow value of the (A) component is an index showing the fluidity of the absorbent particles swollen with water, and this index is thought to correlate with the degree of cross-linking of the absorbent particles, and it is presumed that the smaller the tapping flow value, the greater the degree of cross-linking of the absorbent particles. The greater the degree of cross-linking of the absorbent particles, the less likely the absorbent particles will swell even if they absorb water in soft soil. In the present invention, by using absorbent particles with a specific tapping flow value, the moisture in the soft soil is reduced while the increase in viscosity of the modified soil due to the particles after water absorption is suppressed, improving the compactability and developing strength after curing. In addition, the quicklime of the (B) component reacts with water to become calcium hydroxide, which generates a large amount of heat at the time. The (B) component reduces the amount of moisture in the wet soil by taking in water as a chemical reaction and promoting the evaporation of water by heat generation, and is thought to further synergistically improve the compactability improved by the (A) component.
［改質土壌の製造方法］
本発明では、含水比が１００質量％以上の軟弱土壌に、（Ａ）成分と（Ｂ）成分とを添加して改質土壌を製造する。本発明で得られる改質土壌は、例えば、軟弱土壌を脱水作用により土壌の含水比を低下させ、粘性や付着性を低下させた土壌であり、運搬・再利用時の利便性の観点から、粒状化させた土壌（粒状土）であることが好ましい。
[Method of manufacturing modified soil]
In the present invention, modified soil is produced by adding components (A) and (B) to soft soil having a water content of 100% by mass or more. The modified soil obtained by the present invention is, for example, soft soil whose water content has been reduced by dehydration, and whose viscosity and adhesiveness have been reduced, and is preferably granulated soil (granular soil) from the viewpoint of convenience in transportation and reuse.
本発明の対象とする軟弱土壌は、含水比が１００質量％以上である。以下、軟弱土壌という場合、特記しない場合は、含水比が１００質量％以上の土壌をさす。土壌の含水比とは土壌の固形分に対する水分の質量比率である。軟弱土壌の含水比は、例えば、１００質量％以上、好ましくは１１０質量％以上、更に好ましくは１１５質量％以上、そして、１０００質量％以下、好ましくは８００質量％以下、更に好ましくは６００質量％以下、更に好ましくは１５０質量％以下であってよい。含水比が１００質量％以上の軟弱土壌は、例えば、浚渫土、泥炭土、掘削土砂、水害土砂などの土壌に見いだすことができる。また、土壌を乾燥させて、あるいは湿潤させて（例えば水を添加して）含水比を調整しても良い。 The soft soil targeted by the present invention has a water content of 100% by mass or more. Hereinafter, unless otherwise specified, the term "soft soil" refers to soil with a water content of 100% by mass or more. The water content of soil is the mass ratio of water to the solid content of the soil. The water content of soft soil may be, for example, 100% by mass or more, preferably 110% by mass or more, more preferably 115% by mass or more, and 1000% by mass or less, preferably 800% by mass or less, more preferably 600% by mass or less, and more preferably 150% by mass or less. Soft soil with a water content of 100% by mass or more can be found, for example, in soils such as dredged soil, peat soil, excavated soil, and flooded soil. The water content may also be adjusted by drying or wetting the soil (for example, by adding water).
本発明で用いる（Ａ）成分は、水による膨潤時のタッピングフロー値が９０ｍｍ以下の吸水性粒子である。（Ａ）成分のタッピングフロー値は、実施例に記載の方法で測定する。（Ａ）成分のタッピングフロー値は、取り扱い性のよい、例えば粒状の形状の改質土壌を得る観点から、好ましくは８５ｍｍ以下、より好ましくは８０ｍｍ以下であり、そして、再利用時の強度が高い改質土壌を得る観点から、好ましくは５１ｍｍ以上、より好ましくは６０ｍｍ以上、更に好ましくは７０ｍｍ以上である。以下、特記しない限り、（Ａ）成分のタッピングフローとは、水による膨潤時のタッピングフローをいう。 The component (A) used in the present invention is a water-absorbing particle having a tapping flow value of 90 mm or less when swollen with water. The tapping flow value of the component (A) is measured by the method described in the Examples. From the viewpoint of obtaining modified soil having good handleability, for example, a granular shape, the tapping flow value of the component (A) is preferably 85 mm or less, more preferably 80 mm or less, and from the viewpoint of obtaining modified soil having high strength when reused, it is preferably 51 mm or more, more preferably 60 mm or more, and even more preferably 70 mm or more. Hereinafter, unless otherwise specified, the tapping flow of the component (A) refers to the tapping flow when swollen with water.
また、（Ａ）成分の吸水性粒子とは、水と接触するとほぼ瞬時に吸水・膨潤して、水全体をゲル状にする性質を持つ粒子である。吸水性粒子の性質を示す指標として、その粒子が自身の質量に対して粒子内に保持できる水の質量を表す「保水量（ｇ／ｇ）」がある。本発明では、保水量が１０（ｇ／ｇ）以上である粒子を吸水性粒子という。 The water-absorbing particles of component (A) are particles that have the property of absorbing water and swelling almost instantly when they come into contact with water, turning the entire water into a gel. An index of the properties of water-absorbing particles is the "water retention capacity (g/g)," which indicates the mass of water that the particle can hold relative to its own mass. In the present invention, particles with a water retention capacity of 10 (g/g) or more are called water-absorbing particles.
（Ａ）成分のメジアン径（Ｄ５０）は、例えば、１００μｍ以上、更に２００μｍ以上、そして、２０００μｍ以下、更に１０００μｍ以下、更に５００μｍ以下であってよい。（Ａ）成分のメジアン径（Ｄ５０）は、実施例に記載の方法で測定する。 The median diameter ( D50 ) of the component (A) may be, for example, 100 μm or more, and further 200 μm or more, and 2000 μm or less, further 1000 μm or less, and further 500 μm or less. The median diameter ( D50 ) of the component (A) is measured by the method described in the Examples.
（Ａ）成分は、吸水性樹脂粒子が挙げられる。樹脂は、アクリル樹脂、ポリアクリルアミド樹脂、アクリルアミド－アクリル酸系樹脂などが挙げられる。（Ａ）成分は、これらの中でもアクリル樹脂系吸水性粒子が好ましい。
（Ａ）成分は、市販品を用いることができる。吸水性樹脂粒子の市販品としては、例えば三洋化成株式会社製の「サンウェット」シリーズ、日本触媒株式会社製の「アクアリック」シリーズなどがあり、これらの中から、吸水性粒子が水によって膨潤した時のタッピングフロー値が９０ｍｍ以下のものを選択して（Ａ）成分として使用することができる。
The component (A) may be water-absorbing resin particles. Examples of the resin include acrylic resin, polyacrylamide resin, acrylamide-acrylic acid resin, etc. Among these, the component (A) is preferably acrylic resin water-absorbing particles.
As the component (A), a commercially available product can be used. Commercially available water-absorbent resin particles include, for example, the "Sunwet" series manufactured by Sanyo Chemical Industries, Ltd. and the "Aqualic" series manufactured by Nippon Shokubai Co., Ltd. Among these, a water-absorbent particle having a tapping flow value of 90 mm or less when swollen with water can be selected and used as the component (A).
本発明で用いる（Ｂ）成分は、生石灰である。生石灰は、工業的に入手できるものが使用できる。（Ｂ）成分は、メジアン径（Ｄ５０）が１０μｍ以上、１０００μｍ以下のものが好ましい。 The component (B) used in the present invention is quicklime. Any quicklime available on an industrial scale can be used. The component (B) preferably has a median diameter (D 50 ) of 10 μm or more and 1000 μm or less.
本発明では、軟弱土壌１ｍ３に対して、（Ａ）成分を、好ましくは１０ｋｇ以上、更に好ましくは１５ｋｇ以上、更に好ましくは２０ｋｇ以上、そして、好ましくは６０ｋｇ以下、更に好ましくは５０ｋｇ以下、更に好ましくは３０ｋｇ以下の割合で添加することができる。 In the present invention, component (A ) can be added at a rate of preferably 10 kg or more, more preferably 15 kg or more, even more preferably 20 kg or more, and preferably 60 kg or less, more preferably 50 kg or less, even more preferably 30 kg or less per 1 m3 of soft soil.
本発明では、軟弱土壌１ｍ３に対して、（Ｂ）成分を、好ましくは３０ｋｇ以上、更に好ましくは４０ｋｇ以上、そして、好ましくは２００ｋｇ以下、更に好ましくは１００ｋｇ以下、更に好ましくは７５ｋｇ以下の割合で添加することができる。 In the present invention, component (B) can be added at a rate of preferably 30 kg or more, more preferably 40 kg or more, and preferably 200 kg or less, more preferably 100 kg or less, and more preferably 75 kg or less per 1 m3 of soft soil.
本発明では、（Ａ）成分の添加量と（Ｂ）成分の添加量との質量比である（Ａ）／（Ｂ）が、好ましくは０．０５以上、更に好ましくは０．１以上、更に好ましくは０．３以上、そして、好ましくは２以下、更に好ましくは１．７以下、更に好ましくは１．０以下、更に好ましくは０．５以下であってよい。 In the present invention, the mass ratio (A)/(B) of the amount of component (A) added to the amount of component (B) added is preferably 0.05 or more, more preferably 0.1 or more, more preferably 0.3 or more, and preferably 2 or less, more preferably 1.7 or less, more preferably 1.0 or less, and more preferably 0.5 or less.
本発明では、本発明の効果を損なわない範囲で、（Ａ）成分、（Ｂ）成分以外の成分を、任意に軟弱土壌に添加することもできる。そのような成分としては、土の凝集をほぐし、凝集内部に取り込まれている水を自由水として排出させる粘土粒子用分散剤が挙げられる。一般的な粘土粒子用分散剤としてポリアクリル酸ナトリウムやナフタレンスルホン酸ホルマリン縮合物が挙げられる。ただし、（Ａ）成分に該当するものは除かれる。 In the present invention, components other than components (A) and (B) can be added to the soft soil as long as they do not impair the effects of the present invention. Such components include dispersants for clay particles that break up soil aggregates and expel water trapped inside the aggregates as free water. Common dispersants for clay particles include sodium polyacrylate and naphthalenesulfonic acid-formalin condensate. However, these do not fall under the category of component (A).
（Ａ）成分と（Ｂ）成分の軟弱土壌への添加方法は特に限定はないが、（Ａ）成分と（Ｂ）成分をそれぞれ粉体の状態で軟弱土壌に添加し、必要に応じて公知の撹拌手段で撹拌して、混合すればよい。 There are no particular limitations on the method of adding components (A) and (B) to soft soil, but components (A) and (B) may be added in powder form to the soft soil, and mixed by stirring using known stirring means as necessary.
また、（Ａ）成分と（Ｂ）成分の軟弱土壌への添加を簡便にするために、成分（Ａ）と成分（Ｂ）とを含有する軟弱土壌用添加剤を予め調製し、前記添加剤を軟弱土壌に添加して用いることができる。本発明により、（Ａ）成分と、（Ｂ）成分とを含有する、軟弱土壌用添加剤が提供される。本発明の軟弱土壌用添加剤は、例えば、軟弱土壌用改質剤であってよい。本発明の軟弱土壌用添加剤は、（Ａ）成分の含有量と（Ｂ）成分の含有量との質量比である（Ａ）／（Ｂ）が、好ましくは０．０５以上、更に好ましくは０．１以上、更に好ましくは０．３以上、そして、好ましくは２以下、更に好ましくは１．７以下、更に好ましくは１．０以下、更に好ましくは０．５以下であってよい。 In order to simplify the addition of the (A) and (B) components to soft soil, an additive for soft soil containing the (A) and (B) components can be prepared in advance and added to the soft soil. The present invention provides an additive for soft soil containing the (A) and (B) components. The additive for soft soil of the present invention may be, for example, a modifier for soft soil. The additive for soft soil of the present invention may have a mass ratio (A)/(B) of the content of the (A) component to the content of the (B) component, which is preferably 0.05 or more, more preferably 0.1 or more, more preferably 0.3 or more, and preferably 2 or less, more preferably 1.7 or less, more preferably 1.0 or less, and more preferably 0.5 or less.
（Ａ）成分と（Ｂ）成分が添加された軟弱土壌は、例えば添加量が前記範囲であれば、比較的短時間で粘性や付着性を低下させた改質土壌となり、また、取り扱い性がよい形状、好ましくは粒状となる。
本発明により得られた改質土壌は、例えば、嵩密度が１．１ｇ／ｃｍ３以上１．５ｇ／ｍ３以下である。
Soft soil to which components (A) and (B) have been added, for example, in amounts within the above-mentioned ranges, becomes improved soil with reduced viscosity and adhesiveness in a relatively short period of time, and also takes on a shape that is easy to handle, preferably granular.
The improved soil obtained by the present invention has, for example, a bulk density of 1.1 g/cm 3 or more and 1.5 g/m 3 or less.
本発明により得られた改質土壌は、粘性が低い状態、好ましくはさらさらした状態の粒状であるので、運搬などの取り扱い性がよいものとなる。また、締固めなどにより圧縮した後の強度が高いため、この性質が好ましい分野での利用価値が高いものとなる。
本発明により得られた改質土壌は、各種分野で利用できる。なかでも土木分野での土として、更には盛土として好適に利用できる。
The improved soil obtained by the present invention is in a low viscosity state, preferably in a free-flowing granular state, and therefore has good handling properties for transportation, etc. In addition, since it has high strength after being compressed by compaction, etc., it is highly useful in fields where this property is preferred.
The improved soil obtained by the present invention can be used in various fields, and is particularly suitable for use as soil in the civil engineering field, and further as banking soil.
本発明により得られた改質土壌は、用途にもよるが、締固め後の土壌強度が、例えば、１５０ｋＮ／ｍ２以上、更に２００ｋＮ／ｍ２以上であってよい。また、撤去を前提とした一時的な盛土のように、ある程度の強度が発現すればよい用途に本発明により得られた改質土壌を利用する場合は、前記土壌強度の上限値は、例えば、１５００ｋＮ／ｍ２以下、更に５００ｋＮ／ｍ２以下であってよい。この締固め後の土壌強度は、実施例記載の方法による土壌強度である。 The improved soil obtained by the present invention may have a soil strength after compaction of, for example, 150 kN/m2 or more , or even 200 kN/m2 or more , depending on the application. When the improved soil obtained by the present invention is used for an application in which a certain degree of strength is sufficient, such as a temporary embankment intended to be removed, the upper limit of the soil strength may be, for example, 1500 kN/m2 or less, or even 500 kN/m2 or less. This soil strength after compaction is the soil strength measured by the method described in the Examples.
［盛土の施工方法］
本発明は、含水比が１００質量％以上の軟弱土壌に、タッピングフロー値が９０ｍｍ以下の架橋度の高い吸水性粒子（Ａ）〔（Ａ）成分〕と生石灰（Ｂ）〔（Ｂ）成分〕とを添加して、改質土壌を得、得られた改質土壌を用いて盛土を構築する、盛土の施工方法を提供する。
本発明の盛土の施工方法には、本発明の改質土壌の製造方法で述べた事項を適宜適用することができる。本発明の盛土の施工方法における（Ａ）成分、（Ｂ）成分の具体例や好ましい例なども本発明の改質土壌の製造方法と同じである。本発明の盛土の施工方法では、改質土壌を得る方法は、本発明の改質土壌の製造方法によることができる。
得られた改質土壌を用いて盛土を構築する方法は、公知の盛土の構築方法に準ずることができる。本発明では、改質土壌を締固めて盛土を構築することができる。締固めの条件は、例えば、締固め度で管理され、一般的に道路盛土で９０％以上、河川堤防で８５％以上である。締固め度とは、現場で締固めた土の乾燥密度と基準の締固め試験の最大乾燥密度との比である。改質土壌の締固めは、公知の土壌の締固め方法で行うことができる。
[Embankment construction method]
The present invention provides a method for constructing an embankment, comprising the steps of: adding highly cross-linked water-absorbent particles (A) [(A) component] having a tapping flow value of 90 mm or less and quicklime (B) [(B) component] to soft soil having a moisture content of 100 mass % or more to obtain modified soil; and using the modified soil to construct an embankment.
The matters described in the modified soil manufacturing method of the present invention can be appropriately applied to the embankment construction method of the present invention. Specific examples and preferred examples of the (A) component and the (B) component in the embankment construction method of the present invention are the same as those in the modified soil manufacturing method of the present invention. In the embankment construction method of the present invention, the modified soil can be obtained by the modified soil manufacturing method of the present invention.
The method of constructing embankments using the obtained modified soil can be based on known methods of constructing embankments. In the present invention, the modified soil can be compacted to construct an embankment. The compaction conditions are controlled, for example, by the degree of compaction, which is generally 90% or more for road embankments and 85% or more for river levees. The degree of compaction is the ratio between the dry density of soil compacted on-site and the maximum dry density of a standard compaction test. The modified soil can be compacted by known soil compaction methods.
＜評価用軟弱土壌＞
軟弱土壌として、下記物性の関東ローム（赤土）を用いた。
・湿潤密度：１．３７６ｇ／ｃｍ３
・含水比：１１９％
・乾燥密度：０．７５３ｇ／ｃｍ３
<Soft soil for evaluation>
As the soft soil, Kanto loam (red soil) with the following physical properties was used.
Wet density: 1.376 g/ cm3
Water content: 119%
・Dry density: 0.753g/ cm3
＜吸水性樹脂粒子＞
吸水性樹脂粒子として、下記の吸水性樹脂粒子を用いた。各吸水性樹脂粒子のタッピングフロー値とメジアン径（Ｄ５０）は、それぞれ、以下の方法で測定した。なお、いずれも保水量は１０（ｇ／ｇ）以上であった。
・本発明品１：タッピングフロー値７９ｍｍ、メジアン径（Ｄ５０）４００μｍ、アクリル樹脂系吸水性粒子
・本発明品２：タッピングフロー値７７ｍｍ、メジアン径（Ｄ５０）３８０μｍ、アクリル樹脂系吸水性粒子
・比較品１：タッピングフロー値１２７ｍｍ、メジアン径（Ｄ５０）４００μｍ、アクリル樹脂系吸水性粒子
・比較品２：タッピングフロー値１０２ｍｍ、メジアン径（Ｄ５０）３８０μｍ、アクリル樹脂系吸水性粒子
<Water-absorbent resin particles>
The following water-absorbent resin particles were used as the water-absorbent resin particles. The tapping flow value and median diameter ( D50 ) of each water-absorbent resin particle were measured by the following methods. The water retention capacity of each was 10 (g/g) or more.
Invention product 1: tapping flow value 79 mm, median diameter ( D50 ) 400 μm, acrylic resin-based water-absorbing particles Invention product 2: tapping flow value 77 mm, median diameter ( D50 ) 380 μm, acrylic resin-based water-absorbing particles Comparative product 1: tapping flow value 127 mm, median diameter ( D50 ) 400 μm, acrylic resin-based water-absorbing particles Comparative product 2: tapping flow value 102 mm, median diameter ( D50 ) 380 μm, acrylic resin-based water-absorbing particles
＜吸水性粒子のタッピングフロー値の測定方法＞
（１）５００ｍＬのプラスチックカップに乾燥状態の吸水性粒子１ｇを秤量し、イオン交換水２００ｇを添加する。その後、２０℃で１０分間、静置する。
（２）膨潤後、吸水性粒子の表面に自由水があれば取り除く。
（３）タッピング台の上にフロー板を設置し、その上に内径５０ｍｍ、外径６０ｍｍ、高さ５０ｍｍの円筒形のプラスチックコーンを置き、膨潤した吸水性粒子をコーンに充填する。
（４）コーンを垂直に引き上げ、その後、１０回のタッピングを行う。
（５）吸水性粒子の拡がりの最も長い径とその垂直の径をノギスで測定し、平均値を水による膨潤時のタッピングフロー値とする。
<Method for measuring tapping flow value of water-absorbing particles>
(1) 1 g of dry water-absorbing particles is weighed into a 500 mL plastic cup, and 200 g of ion-exchanged water is added to the cup. The cup is then left to stand at 20° C. for 10 minutes.
(2) After swelling, any free water present on the surface of the water-absorbing particles is removed.
(3) A flow plate is placed on the tapping table, and a cylindrical plastic cone having an inner diameter of 50 mm, an outer diameter of 60 mm, and a height of 50 mm is placed on the flow plate, and the swollen water-absorbing particles are filled into the cone.
(4) The cone is raised vertically and then tapped 10 times.
(5) The longest diameter of the spread of the water-absorbing particle and the diameter perpendicular to that diameter are measured with a vernier caliper, and the average value is regarded as the tapping flow value when swollen with water.
＜吸水性粒子のメジアン径（Ｄ５０）の測定方法＞
ＪＩＳ Ｚ ８８０１に規定するふるいから、ふるい目開きが７１０μｍ、５００μｍ、３００μｍ、１５０μｍ、受け皿（１５０μｍ以下）の金属製ふるいを選択する。乾燥状態の吸水性粒子をふるい分け、それぞれのふるい上に残った試料の質量を計測し、グラフに質量の累積分布を記載して累積が５０％になる粒子径を読み取り、メジアン径（Ｄ５０）とする。
<Method of measuring the median diameter ( D50 ) of water-absorbing particles>
Metal sieves with sieve openings of 710 μm, 500 μm, 300 μm, 150 μm, and a tray (150 μm or less) are selected from the sieves specified in JIS Z 8801. The water-absorbing particles in a dry state are sieved, the mass of the sample remaining on each sieve is measured, the cumulative distribution of the mass is plotted on a graph, and the particle diameter at which the cumulative distribution is 50% is read and taken as the median diameter (D 50 ).
＜生石灰＞
生石灰として、吉見石灰工業株式会社製、生石灰、特号を用いた。
<Quicklime>
As the quicklime, special quicklime manufactured by Yoshimi Lime Industry Co., Ltd. was used.
＜評価方法＞
モルタルミキサーに、軟弱土壌（関東ローム）、表に示す（Ａ）成分、及び表に示す（Ｂ）成分を、表に示す混合量で投入し、低速で３分間混錬した。混練後、実施例では粒状の土が得られたが、比較例では粒状の土は得られず、粘性のある塊状の土が得られた。実施例で得られた粒状土は、嵩密度が１．１ｇ／ｃｍ３以上１．５ｇ／ｍ３以下の範囲にあった。図１に、実施例１－１で得られた粒状の土を示した。また、図２に、比較例１－１で得られた塊状の土を示した。図１に示すように、実施例１－１で得られた土は、微細な粒状で、かつさらさらした状態であった。一方、図２に示すように、比較例１－１で得られた土は、粗大で粘性の高い塊状のものであった。
得られた土をサミットモールドに３層で詰め、締固め（１．５ｋｇランマー使用。各層２５回締固め）を行った。締固め後、２０℃条件の空気中にて５時間、養生を行った。養生後、山中式土壌硬度計（株式会社藤原製作所：標準型土壌硬度計Ｎｏ．３５１）を用いて硬度指数（ばね縮長）を測定した。前記土壌硬度計の取扱説明書に従い、土壌硬度計の先端コーンを鍔と土壌サンプルの表面が当たるまで差し込み、ゆっくりと引き抜いた。その際の目盛の硬度指数（ｍｍ）を読み取り、次式にて支持力強度（ｋｇ／ｃｍ２）に換算した。更に、支持力強度をｋＮ／ｍ２に換算し、土壌硬度として表１、２に示した。
Ｐ＝〔１００Ｘ〕／〔０．７９５２（４０－Ｘ）２〕
Ｐ：支持力強度（ｋｇ／ｃｍ２）
Ｘ：硬度指数（ばね縮長）（ｍｍ）
<Evaluation method>
The soft soil (Kanto loam), the (A) component shown in the table, and the (B) component shown in the table were charged into a mortar mixer in the amounts shown in the table, and kneaded at low speed for 3 minutes. After kneading, granular soil was obtained in the examples, but no granular soil was obtained in the comparative examples, and viscous lumpy soil was obtained. The granular soil obtained in the examples had a bulk density in the range of 1.1 g/cm 3 to 1.5 g/m 3. Figure 1 shows the granular soil obtained in Example 1-1. Figure 2 shows the lumpy soil obtained in Comparative Example 1-1. As shown in Figure 1, the soil obtained in Example 1-1 was finely granulated and in a loose state. On the other hand, as shown in Figure 2, the soil obtained in Comparative Example 1-1 was coarse and viscous lumpy.
The obtained soil was packed in a summit mold in three layers and compacted (using a 1.5 kg rammer. Each layer was compacted 25 times). After compaction, the soil was cured in air at 20°C for 5 hours. After curing, the hardness index (spring contraction length) was measured using a Yamanaka soil hardness meter (Fujiwara Seisakusho Co., Ltd.: Standard soil hardness meter No. 351). According to the instruction manual for the soil hardness meter, the tip cone of the soil hardness meter was inserted until the flange and the surface of the soil sample touched each other, and then slowly pulled out. The hardness index (mm) on the scale at that time was read and converted to bearing strength (kg/cm 2 ) using the following formula. Furthermore, the bearing strength was converted to kN/m 2 and shown as soil hardness in Tables 1 and 2.
P=[100X]/[0.7952(40-X) 2 ]
P: Supporting strength (kg/cm 2 )
X: Hardness index (spring contraction length) (mm)
Claims (7)
軟弱土壌１ｍ ３ に対して、（Ａ）成分を１０ｋｇ以上５０ｋｇ以下添加し、
（Ａ）成分の添加量と（Ｂ）成分の添加量との質量比である（Ａ）／（Ｂ）が、０．１以上１．０以下である、改質土壌の製造方法。 A method for producing improved soil , comprising the steps of: placing a cylindrical plastic cone having an inner diameter of 50 mm, an outer diameter of 60 mm, and a height of 50 mm on soft soil having a moisture content of 100% by mass or more; filling the cone with swollen water-absorbing particles; vertically lifting the cone; and adding water-absorbing particles (A) (hereinafter referred to as component (A)) having a median diameter (D50 ) of 200 μm to 500 μm and a tapping flow value of 70 mm to 80 mm obtained by performing 10 tapping operations; and quicklime (B) (hereinafter referred to as component (B)).
Add 10 kg to 50 kg of component (A) per 1 m3 of soft soil .
A method for producing improved soil, wherein the mass ratio (A)/(B) of the amount of component (A) added to the amount of component (B) added is 0.1 or more and 1.0 or less .
軟弱土壌１ｍ ３ に対して、（Ａ）成分を１０ｋｇ以上５０ｋｇ以下添加し、
（Ａ）成分の添加量と（Ｂ）成分の添加量との質量比である（Ａ）／（Ｂ）が、０．１以上１．０以下である、盛土の施工方法。 A method for constructing embankments, comprising the steps of: placing a cylindrical plastic cone having an inner diameter of 50 mm, an outer diameter of 60 mm, and a height of 50 mm on soft soil having a moisture content of 100% by mass or more; filling the cone with swollen water-absorbing particles; lifting the cone vertically; and then adding water-absorbing particles (A) and quicklime (B) having a median diameter (D50 ) of 200 μm to 500 μm and a tapping flow value of 70 mm to 80 mm obtained by performing 10 tapping operations to obtain modified soil, and constructing an embankment using the modified soil, the method comprising the steps of:
Add 10 kg to 50 kg of component (A) per 1 m3 of soft soil .
A method for constructing embankments, wherein the mass ratio (A)/(B) of the amount of component (A) added to the amount of component (B) added is 0.1 or more and 1.0 or less .
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| JP2018168628A (en) | 2017-03-30 | 2018-11-01 | 三菱マテリアル株式会社 | Method for producing granulated soil and method for granulating swelled portion using this method |
| JP2020163265A (en) | 2019-03-29 | 2020-10-08 | 株式会社奥村組 | Classification cleaning treatment method for contaminated soil |
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| JP2008037934A (en) | 2006-08-02 | 2008-02-21 | Nippon Shokubai Co Ltd | Hydrous soil improving agent, granulating method and granular soil |
| JP2018168628A (en) | 2017-03-30 | 2018-11-01 | 三菱マテリアル株式会社 | Method for producing granulated soil and method for granulating swelled portion using this method |
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