JP7614039B2 - Quality control method for liquefied treated soil - Google Patents
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Description
本発明は、流動化処理土の品質管理方法に関するものである。 The present invention relates to a method for quality control of liquefied treated soil.
従来、再開発案件では、新設構造物に既存構造物の躯体や杭を再利用しない場合、新設構造物に干渉する既存構造物の一部を予め撤去し、その領域を埋戻すのが通常である。埋戻し材料には、強度の発現性と安定性を確保しやすい流動化処理土を用いることが多い。流動化処理土は、主に建設発生土と水、セメントから構成され、流動性と自硬性を有することから、狭小な空間や締固めの困難な箇所の埋戻し・裏込め・充填工事にも採用される。例えば、既存杭撤去・埋戻し工事では、既存杭径より大径なケーシングを地盤に回転圧入し、ケーシング内部をハンマークラブ等で破砕・撤去した後に、流動化処理土をトレミー管で撤去した孔底から注入することがある。しかしながら、撤去・埋戻し孔長が長尺になると、流動化処理土の浅部においてブリーディング等による材料分離が生じ、強度が不安定となる事例が報告されている（例えば、非特許文献１を参照）。 In the past, in redevelopment projects, if the framework or piles of an existing structure are not reused in a new structure, it is common to remove a portion of the existing structure that interferes with the new structure in advance and backfill the area. Fluidized treated soil, which is easy to ensure strength expression and stability, is often used as a backfill material. Fluidized treated soil is mainly composed of construction waste soil, water, and cement, and has fluidity and self-hardening properties, so it is also used for backfilling, backfilling, and filling work in narrow spaces and places where compaction is difficult. For example, in existing pile removal and backfilling work, a casing with a larger diameter than the existing pile diameter is rotary-pressed into the ground, and the inside of the casing is crushed and removed with a hammer club, etc., and then fluidized treated soil is injected from the bottom of the hole that was removed with a tremie pipe. However, when the removal and backfilling hole length becomes long, there have been reported cases where material separation due to bleeding, etc. occurs in the shallow part of the fluidized treated soil, causing the strength to become unstable (see, for example, Non-Patent Document 1).
一般的な流動化処理土の品質は、製造時あるいは打設時の吐出口から採取したモールド試験体の強度で検査する（例えば、特許文献１を参照）。原位置強度の確認は、「必要に応じて原位置において不攪乱試料を採取して、強度を確認する」に留まり（例えば、非特許文献２を参照）、実施の判断は事業者に依る。 The quality of typical liquefied treated soil is inspected by checking the strength of molded specimens taken from the discharge port during production or pouring (see, for example, Patent Document 1). Verification of in-situ strength is limited to "taking undisturbed samples in-situ as necessary to confirm strength" (see, for example, Non-Patent Document 2), and the decision to implement this is left to the operator.
一方、ソイルセメントの強度を化学的な手法により判定する方法として、例えば、特許文献２～８に記載の方法（以下、ＣＷ－ＱＵＩＣという。）が知られている。また、せん断波速度を用いてソイルセメントの品質を管理する方法として、例えば、特許文献９、１０に記載の方法（以下、Ｖｓ－ＱＵＩＣという。）が知られている。
Means for determining the strength of soil cement using chemical techniques include, for example, the methods described in
流動化処理土の強度不足の例として、２つの事例を図に示す。図４（１）は非特許文献１に記載のもの（Ａ現場と表記）、図４（２）は近年調査されたＢ現場のものである。これらの図に示すように、吐出口から採取したモールド試験体の強度は、Ａ現場で４００～４５０ｋＰａ、Ｂ現場で２４０ｋＰａであり、いずれも設計基準強度を満足している。しかしながら、ボーリングコアを採取した不攪乱試料の原位置強度は、特に浅部で設計基準強度を満足していない。 Two examples of insufficient strength of liquefied treated soil are shown in the figures. Figure 4 (1) is from the one described in Non-Patent Document 1 (labeled Site A), and Figure 4 (2) is from Site B, which was investigated recently. As shown in these figures, the strength of the molded test specimens taken from the discharge outlet was 400-450 kPa at Site A and 240 kPa at Site B, both of which met the design standard strength. However, the in-situ strength of the undisturbed samples taken from boring cores did not meet the design standard strength, especially in the shallow areas.
このように流動化処理土の原位置強度が設計基準強度を満足しない場合、既存杭撤去・埋戻し工事においては、新設杭施工時に孔曲がりや孔壁崩壊、杭芯ずれ等の不具合を生じ、新設杭の設計に用いる地盤物性値の見直し作業が発生するおそれがある。このような事態を回避するためには、埋戻し部を再掘削し、埋め戻す必要があるが、工期の圧迫と施工および材料費用の増大を招くこととなる。このため、流動化処理土の強度の不安定性を回避することができる品質管理方法が求められていた。 If the in-situ strength of liquefied treated soil does not meet the design standard strength in this way, problems such as hole bending, collapse of hole walls, and displacement of the pile core may occur when constructing new piles during work to remove existing piles and backfill them, which may require a review of the soil properties used in the design of the new piles. To avoid such situations, it is necessary to re-excavate and refill the backfilled areas, but this will shorten the construction period and increase construction and material costs. For this reason, a quality control method that can avoid the instability of the strength of liquefied treated soil is needed.
本発明は、上記に鑑みてなされたものであって、強度の不安定性を回避することができる流動化処理土の品質管理方法を提供することを目的とする。 The present invention has been made in consideration of the above, and aims to provide a quality control method for liquefied treated soil that can avoid strength instability.
上記した課題を解決し、目的を達成するために、本発明に係る流動化処理土の品質管理方法は、土質材料とセメント系固化材と水とを含有するとともに、地盤に打設して施工される流動化処理土の施工品質を管理するための方法であって、流動化処理土の配合計画の際に、土質材料の細粒分含有率またはセメント系固化材の添加量を調整して、流動化処理土の粘度を材料分離抵抗性を高める所定の範囲内に予め調整するステップと、施工直前の未固結状態の流動化処理土を採取するステップと、採取した流動化処理土の粘度を測定し、測定した粘度が所定の範囲内であるか否かを判定するステップと、採取した流動化処理土に含まれるセメント系固化材量または水に対するセメント系固化材の配合比率を推定し、推定したセメント系固化材量または配合比率が、設計基準強度に基づいて設定した所定の範囲内であるか否かを判定するステップと、施工後の固結状態の流動化処理土のせん断波速度を測定し、測定したせん断波速度が、設計基準強度に基づいて設定した所定の範囲内であるか否かを判定するステップとを有することを特徴とする。 In order to solve the above problems and achieve the objectives, the quality control method for liquefied treated soil according to the present invention is a method for controlling the construction quality of liquefied treated soil that contains soil material, cement-based solidification material, and water and is poured into the ground for construction, and is characterized by having the steps of: adjusting the fine particle content of the soil material or the amount of cement-based solidification material added when planning the mixture for the liquefied treated soil, thereby adjusting the viscosity of the liquefied treated soil in advance within a predetermined range that enhances the resistance to material separation; sampling the liquefied treated soil in an unconsolidated state immediately before construction; measuring the viscosity of the sampled liquefied treated soil and determining whether the measured viscosity is within the predetermined range; estimating the amount of cement-based solidification material contained in the sampled liquefied treated soil or the mixture ratio of the cement-based solidification material to water, and determining whether the estimated amount of cement-based solidification material or the mixture ratio is within a predetermined range set based on the design standard strength; and measuring the shear wave velocity of the liquefied treated soil in a solidified state after construction and determining whether the measured shear wave velocity is within a predetermined range set based on the design standard strength.
また、本発明に係る他の流動化処理土の品質管理方法は、上述した発明において、流動化処理土を酸で中和した際の初期のｐＨの時間変化特性を利用して、セメント系固化材量または配合比率を推定することを特徴とする。 Another quality control method for liquefied treated soil according to the present invention is characterized in that, in the above-mentioned invention, the amount or mix ratio of cement-based solidification material is estimated by utilizing the time change characteristics of the initial pH when the liquefied treated soil is neutralized with acid.
また、本発明に係る他の流動化処理土の品質管理方法は、上述した発明において、流動化処理土の施工に先立って、土質材料と、セメント系固化材と、水とを混合して配合試験を行うステップをさらに有し、この配合試験は、流動化処理土の供試体についてセメント系固化材添加量と材齢を変えながらせん断波速度の測定と圧縮強度の試験を行い、セメント系固化材添加量と圧縮強度の関係、および、せん断波速度と圧縮強度の関係を取得するステップと、取得した関係に基づいて、所定の設計基準強度に対応するセメント系固化材添加量およびせん断波速度を設定するステップとを含むことを特徴とする。 In addition, another quality control method for liquefied treated soil according to the present invention is characterized in that, in the above-mentioned invention, it further includes a step of conducting a mix test by mixing soil material, cement-based solidification material, and water prior to construction of the liquefied treated soil, and this mix test includes a step of measuring shear wave velocity and testing compressive strength while changing the amount of cement-based solidification material added and the material age for a specimen of liquefied treated soil, obtaining the relationship between the amount of cement-based solidification material added and the compressive strength, and the relationship between shear wave velocity and compressive strength, and a step of setting the amount of cement-based solidification material added and the shear wave velocity corresponding to a predetermined design standard strength based on the obtained relationship.
本発明に係る流動化処理土の品質管理方法によれば、土質材料とセメント系固化材と水とを含有するとともに、地盤に打設して施工される流動化処理土の施工品質を管理するための方法であって、流動化処理土の配合計画の際に、土質材料の細粒分含有率またはセメント系固化材の添加量を調整して、流動化処理土の粘度を材料分離抵抗性を高める所定の範囲内に予め調整するステップと、施工直前の未固結状態の流動化処理土を採取するステップと、採取した流動化処理土の粘度を測定し、測定した粘度が所定の範囲内であるか否かを判定するステップと、採取した流動化処理土に含まれるセメント系固化材量または水に対するセメント系固化材の配合比率を推定し、推定したセメント系固化材量または配合比率が、設計基準強度に基づいて設定した所定の範囲内であるか否かを判定するステップと、施工後の固結状態の流動化処理土のせん断波速度を測定し、測定したせん断波速度が、設計基準強度に基づいて設定した所定の範囲内であるか否かを判定するステップとを有するので、流動化処理土の配合時に材料分離抵抗性を高める粘度調整を行うことで、強度の不安定性を回避することができるという効果を奏する。 According to the quality control method for liquefied treated soil of the present invention, the method is for controlling the construction quality of liquefied treated soil that contains soil material, cement-based solidification material, and water and is poured into the ground for construction, and includes the steps of: adjusting the fine particle content of the soil material or the amount of cement-based solidification material added when planning the mix of the liquefied treated soil, thereby adjusting the viscosity of the liquefied treated soil in advance within a predetermined range that enhances resistance to material separation; sampling the liquefied treated soil in an unconsolidated state immediately before construction; measuring the viscosity of the sampled liquefied treated soil and determining whether the measured viscosity is within the predetermined range; and The method includes a step of estimating the amount of cement-based solidification material contained in the liquefied treated soil or the mixing ratio of the cement-based solidification material to water, and judging whether the estimated amount of cement-based solidification material or the mixing ratio is within a predetermined range set based on the design standard strength, and a step of measuring the shear wave velocity of the liquefied treated soil in a solidified state after construction, and judging whether the measured shear wave velocity is within a predetermined range set based on the design standard strength. This has the effect of avoiding strength instability by adjusting the viscosity to increase the material separation resistance when mixing the liquefied treated soil.
また、本発明に係る他の流動化処理土の品質管理方法によれば、流動化処理土を酸で中和した際の初期のｐＨの時間変化特性を利用して、セメント系固化材量または配合比率を推定するので、迅速かつ安価にセメント系固化材量または配合比率を推定することができるという効果を奏する。 In addition, according to another quality control method for liquefied treated soil of the present invention, the amount or mix ratio of cement-based solidification material is estimated by utilizing the time change characteristics of the initial pH when the liquefied treated soil is neutralized with acid, which has the effect of enabling the amount or mix ratio of cement-based solidification material to be estimated quickly and inexpensively.
また、本発明に係る他の流動化処理土の品質管理方法によれば、流動化処理土の施工に先立って、土質材料と、セメント系固化材と、水とを混合して配合試験を行うステップをさらに有し、この配合試験は、流動化処理土の供試体についてセメント系固化材添加量と材齢を変えながらせん断波速度の測定と圧縮強度の試験を行い、セメント系固化材添加量と圧縮強度の関係、および、せん断波速度と圧縮強度の関係を取得するステップと、取得した関係に基づいて、所定の設計基準強度に対応するセメント系固化材添加量およびせん断波速度を設定するステップとを含むので、所定の設計基準強度の発現に必要なセメント系固化材添加量およびせん断波速度を精度よく把握することができるという効果を奏する。 In addition, another quality control method for liquefied treated soil according to the present invention further includes a step of performing a mix test by mixing soil material, cement-based solidification material, and water prior to construction of the liquefied treated soil. This mix test includes a step of measuring shear wave velocity and testing compressive strength while changing the amount of cement-based solidification material added and the material age for a specimen of liquefied treated soil, obtaining the relationship between the amount of cement-based solidification material added and the compressive strength, and the relationship between shear wave velocity and compressive strength, and a step of setting the amount of cement-based solidification material added and the shear wave velocity corresponding to a specified design standard strength based on the obtained relationship, thereby achieving the effect of accurately grasping the amount of cement-based solidification material added and the shear wave velocity required to realize the specified design standard strength.
以下に、本発明に係る流動化処理土の品質管理方法の実施の形態を図面に基づいて詳細に説明する。なお、この実施の形態によりこの発明が限定されるものではない。 Below, an embodiment of the quality control method for liquefied treated soil according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment.
上述したように、流動化処理土の材料分離抵抗性を確保できる配合が重要となる。したがって、本実施の形態では、流動化処理土の粘度を適切に確保しつつ、設計基準強度に対応した固化材添加量とせん断波速度を決定する。次に、検査対象となる流動化処理土を受け入れ検査として未固結状態で採取し、流動化処理土の強度を化学的な手法により判定する方法（ＣＷ－ＱＵＩＣ）によって、強度発現に必要なセメント添加量を満足していることを確認する。流動化処理土が固化した後は、流動化処理土の表面において、せん断波速度を用いた品質検査方法（Ｖｓ－ＱＵＩＣ）を実施し、原位置強度が設計基準強度を満足していることを確認する。なお、本発明は流動化処理土の適用先に限定されない。
以下に、本実施の形態の具体的な実施手順について説明する。
As described above, it is important to have a mix that can ensure the resistance to material separation of the liquefied treated soil. Therefore, in this embodiment, the amount of solidification material to be added and the shear wave velocity corresponding to the design standard strength are determined while the viscosity of the liquefied treated soil is appropriately ensured. Next, the liquefied treated soil to be inspected is sampled in an unconsolidated state as an acceptance inspection, and the strength of the liquefied treated soil is confirmed to be sufficient in the amount of cement to be added for strength development by a method (CW-QUIC) that determines the strength of the liquefied treated soil by a chemical method. After the liquefied treated soil has solidified, a quality inspection method (Vs-QUIC) using shear wave velocity is performed on the surface of the liquefied treated soil to confirm that the in-situ strength satisfies the design standard strength. Note that the present invention is not limited to the application of the liquefied treated soil.
A specific implementation procedure of this embodiment will be described below.
（室内配合試験）
図１に示すように、流動化処理土の実施工に先立ち、以下のステップＳ１～Ｓ４による室内配合試験を行う。
まず、ステップＳ１では、流動化処理土製造プラントのストックヤードから対象土質材料（例えば、建設発生土）を採取し、細粒分含有率を調整する。この調整は一般的な粒度調整の手順で行うことができる。調整後の細粒分含有率は、５％～３０％であることが望ましく、１０％～２０％であることがより望ましい。採取時の対象土質材料の細粒分含有率があらかじめ設定した所定範囲（例えば上記の範囲）に分布する場合は、このステップＳ１を省略できる。なお、細粒分の調整はベントナイト等の添加によっても可能であるが、フロー低下を生じやすくなるおそれがある。このため、フロー保持性が求められる流動化処理土の場合は、ストックヤードに保管してある対象土質材料を組み合わせて細粒分を調整したり、規定の細粒分含有率を満足する建設発生土等の土質材料を採用して調整することが望ましい。
(Indoor blending test)
As shown in Figure 1, prior to the actual construction of the liquefied treated soil, an indoor mix test is conducted according to the following steps S1 to S4.
First, in step S1, the target soil material (e.g., construction waste soil) is collected from the stockyard of the liquefied soil manufacturing plant, and the fine particle content is adjusted. This adjustment can be performed by a general grain size adjustment procedure. The fine particle content after adjustment is preferably 5% to 30%, more preferably 10% to 20%. If the fine particle content of the target soil material at the time of collection is distributed within a predetermined range (e.g., the above range), this step S1 can be omitted. The fine particle content can also be adjusted by adding bentonite, etc., but there is a risk that flow reduction will occur easily. For this reason, in the case of liquefied soil that requires flow retention, it is desirable to adjust the fine particle content by combining the target soil material stored in the stockyard, or to adopt soil material such as construction waste soil that satisfies the specified fine particle content.
次のステップＳ２では、上記のステップＳ１で粒度調整した対象土質材料に対して、セメント系固化材の添加量を３～４水準程度設定し、流動化処理土を作製する。セメント系固化材の添加量は、例えば５０ｋｇ／ｍ３～４００ｋｇ／ｍ３の間で変化させる。ただし、この時の粘度μｓｐｅは、流動化処理土の材料分離抵抗性を高めるために、５００ｍＰａ・ｓ～４０００ｍＰａ・ｓであることが望ましく、ブリーディングを生じない１５００ｍＰａ・ｓ～３０００ｍＰａ・ｓであることがより望ましい。流動化処理土の粘度は、セメント系固化材の添加量や、使用する対象土質材料の細粒分含有率によって調整することができる。流動化処理土の供試体は、配合毎に３０本程度作製することが望ましい。 In the next step S2, the amount of cement-based solidification material added to the target soil material whose grain size has been adjusted in step S1 is set to about 3 to 4 levels, and fluidized treated soil is prepared. The amount of cement-based solidification material added is changed between 50 kg/m 3 and 400 kg/m 3 , for example. However, the viscosity μspe at this time is preferably 500 mPa·s to 4000 mPa·s in order to increase the material separation resistance of the fluidized treated soil, and more preferably 1500 mPa·s to 3000 mPa·s in order not to cause bleeding. The viscosity of the fluidized treated soil can be adjusted by the amount of cement-based solidification material added and the fine grain content of the target soil material used. It is desirable to prepare about 30 specimens of fluidized treated soil for each mix.
次のステップＳ３では、材齢を変化させた流動化処理土の供試体を用いて、せん断波速度Ｖｓの測定と圧縮試験を実施する。例えば、材齢８時間、１２時間、２４時間、２日、３日、７日、１４日、２８日について実施するのが好ましいが、これ以外の材齢でもよい。Ｖｓ測定と圧縮試験の供試体数は、１つの材齢に対して２～３本とするのが好ましい。 In the next step S3, measurements of shear wave velocity Vs and compression tests are carried out using specimens of liquefied treated soil with varying material ages. For example, it is preferable to carry out the tests at material ages of 8 hours, 12 hours, 24 hours, 2 days, 3 days, 7 days, 14 days, and 28 days, but other material ages are also acceptable. It is preferable to use 2 to 3 specimens for Vs measurements and compression tests for each material age.
次のステップＳ４では、セメント添加量と材齢２８日圧縮強度の関係、および、せん断波速度Ｖｓと圧縮強度の関係を取得する。図２（１）、（２）に、取得された関係の例を示す。続いて、これらの関係に基づいて、設計基準強度Ｆｃ（品質確認上の強度の目標値）に対応する固化材添加量Ｃｓｐｅ、またはセメント水比Ｃ／ＷｓｐｅとＶｓ値（以下、Ｖｓ,ｓｐｅという。）を決定する。固化材添加量Ｃｓｐｅは、設計基準強度Ｆｃの発現に必要な添加量である。 In the next step S4, the relationship between the amount of cement added and the compressive strength at 28 days, and the relationship between the shear wave velocity Vs and the compressive strength are obtained. Examples of the obtained relationships are shown in Figures 2 (1) and (2). Next, based on these relationships, the amount of solidifier added Cspe corresponding to the design standard strength Fc (target value of strength for quality confirmation), or the cement-water ratio C/Wspe and Vs value (hereinafter referred to as Vs,spe) are determined. The amount of solidifier added Cspe is the amount required to achieve the design standard strength Fc.
次のステップＳ５では、上記のステップＳ４を満足する流動化処理土を製造プラントにて作製し、建設現場にデリバリーする。 In the next step S5, liquefied treated soil that satisfies step S4 above is produced at a manufacturing plant and delivered to the construction site.
（粘度の測定）
次に、以下のステップＳ６～Ｓ８で流動処理土の粘度を測定する。
まず、ステップＳ６では、デリバリーされた流動化処理土の受け入れ検査として、配達車から流動化処理土を採取する。
(Viscosity Measurement)
Next, the viscosity of the fluidized treated soil is measured in the following steps S6 to S8.
First, in step S6, the liquefied treated soil is sampled from the delivery vehicle as an acceptance inspection of the delivered liquefied treated soil.
次のステップＳ７では、採取した未固結状態の流動化処理土に対して粘度測定を実施する。例えば、Ｂ型粘度計を利用して、粘度を測定してもよい。 In the next step S7, a viscosity measurement is carried out on the collected unconsolidated liquefied treated soil. For example, the viscosity may be measured using a B-type viscometer.
次のステップＳ８では、測定した粘度が上記のステップＳ２にて定めたμｓｐｅの範囲内であるかを判定する。すなわち、材料分離抵抗に必要な粘度μｓｐｅの範囲内であるという要件を満たすか否かを判定する。判定の結果、合格（範囲内）であれば（ステップＳ８でＹｅｓ）、次のステップＳ９に進む。不合格（範囲外）であれば（ステップＳ８でＮｏ）、製造プラントに返却し（流動化処理土を廃棄する）（ステップＳ１４）、製造方法と配合を見直した後に（ステップＳ１８）、ステップＳ５に戻る。 In the next step S8, it is determined whether the measured viscosity is within the range of μspe determined in step S2 above. In other words, it is determined whether the requirement that the viscosity be within the range of μspe required for material separation resistance is met. If the result of the determination is pass (within range) (Yes in step S8), proceed to the next step S9. If the result is fail (outside range) (No in step S8), return it to the manufacturing plant (discard the liquefied treated soil) (step S14), and after reviewing the manufacturing method and composition (step S18), return to step S5.
（固化材量の推定）
次のステップＳ９では、上記のステップＳ８を満足する未固結状態の流動化処理土に含まれる固化材量を推定する。推定には、例えば上記のＣＷ－ＱＵＩＣを用いることができる。すなわち、流動化処理土を酸で中和した際の初期のｐＨの変化速度（時間変化特性）を利用して、固化材量を推定する。酸は、例えばｐＨ＝２．０程度に調整した一定濃度の酸を用いることができ、例えば塩酸や有機酸などの酸を使用することができる。この方法によれば、流動化処理土の採取から３０分程度での推定が可能である。また、高額な装置を必要としないため安価に実施することができる。したがって、迅速かつ安価に固化材量を推定することができる。参考までに、図２（３）に、流動化処理土が強度を確保していると判定される場合のイメージを示す。
(Estimation of amount of solidification material)
In the next step S9, the amount of solidification material contained in the unconsolidated liquefied soil that satisfies step S8 is estimated. For example, the above-mentioned CW-QUIC can be used for the estimation. That is, the amount of solidification material is estimated by utilizing the initial pH change rate (time change characteristic) when the liquefied soil is neutralized with an acid. For example, an acid of a constant concentration adjusted to about pH = 2.0 can be used, and for example, an acid such as hydrochloric acid or an organic acid can be used. According to this method, it is possible to estimate the amount of solidification material in about 30 minutes after the liquefied soil is collected. In addition, since no expensive equipment is required, it can be performed inexpensively. Therefore, the amount of solidification material can be estimated quickly and inexpensively. For reference, FIG. 2 (3) shows an image of a case where it is determined that the liquefied soil has sufficient strength.
次のステップＳ１０では、推定した流動化処理土に含まれる固化材量が、上記のステップＳ４にて定めた固化材添加量Ｃｓｐｅを満たすか否か、またはセメント水比Ｃ／Ｗｓｐｅを満たすか否かを判定する。判定の結果、満たす場合は（ステップＳ１０でＹｅｓ）、所定の施工品質を充足する（合格）と判定して次のステップＳ１１に進む。満たさない場合は（ステップＳ１０でＮｏ）、所定の施工品質を充足しない（不合格）と判定し、製造プラントに返却し（流動化処理土を廃棄する）（ステップＳ１５）、製造方法と配合を見直した後に（ステップＳ１８）、ステップＳ５に戻る。なお、施工品質は、撹拌が十分行われているか、固化材が十分添加されているか、それにより強度を確保していると判定され得るかなどの施工上の品質である。 In the next step S10, it is determined whether the amount of solidification material contained in the estimated liquefied soil satisfies the amount of solidification material added Cspe determined in step S4 above, or whether it satisfies the cement-water ratio C/Wspe. If it satisfies (Yes in step S10), it is determined that the specified construction quality is met (passed) and the process proceeds to the next step S11. If it does not satisfy (No in step S10), it is determined that the specified construction quality is not met (failed), and the soil is returned to the manufacturing plant (the liquefied soil is discarded) (step S15), and after reviewing the manufacturing method and composition (step S18), the process returns to step S5. The construction quality refers to the quality of the construction, such as whether mixing is sufficient, whether sufficient solidification material is added, and whether it can be determined that strength is ensured as a result.
次のステップＳ１１では、上記のステップＳ１０を満足する未固結状態の流動化処理土を建設現場の所定箇所に打設する。これにより流動化処理土が施工される。 In the next step S11, the unconsolidated liquefied soil that satisfies step S10 above is poured into a designated location at the construction site. This completes the construction of the liquefied soil.
（せん断波速度による強度の推定）
次に、以下のステップＳ１２～Ｓ１３、Ｓ１６で硬化した流動化処理土の強度を推定する。推定には、例えば上記のＶｓ－ＱＵＩＣを用いることができる。
(Estimation of strength from shear wave velocity)
Next, the strength of the hardened liquefied treated soil is estimated in the following steps S12 to S13 and S16. For the estimation, for example, the above-mentioned Vs-QUIC can be used.
まず、ステップＳ１２では、原位置の流動化処理土が硬化した後に、流動化処理土の表面でせん断波速度を測定し、Ｖｓ－ＱＵＩＣを実施する。 First, in step S12, after the in-situ liquefied soil has hardened, the shear wave velocity is measured on the surface of the liquefied soil and Vs-QUIC is performed.
次のステップＳ１３では、測定されたせん断波速度Ｖｓ値が、上記のステップＳ４にて定めたＶｓ,ｓｐｅ以上か否かを判定する。Ｖｓ,ｓｐｅ以上であれば、原位置の流動化処理土の強度が設計基準強度Ｆｃ以上となることが見込まれる。そこで、測定されたＶｓ値がＶｓ,ｓｐｅ以上である場合を合格と判定し、処理を終了する（ステップＳ１３でＹｅｓ）。一方、測定されたＶｓ値がＶｓ,ｓｐｅ未満であり（ステップＳ１３でＮｏ）、かつ測定時の材齢が２８日に満たなければ（ステップＳ１６でＹｅｓ）、ステップＳ１２に戻り、せん断波速度Ｖｓを後日に再度測定する。他方、測定されたＶｓ値がＶｓ,ｓｐｅ未満であり（ステップＳ１３でＮｏ）、かつ測定時の材齢が２８日以降であれば（ステップＳ１６でＮｏ）、打設済み強度不足箇所を掘削し（ステップＳ１７）、製造方法と配合を見直した後に（ステップＳ１８）、ステップＳ５に戻る。なお、せん断波速度Ｖｓ値の測定にはボーリングコアを利用してもよい。この場合、ボーリングコアを採取し、採取したコアに対してＶｓ－ＱＵＩＣを実施すればよい。以上の手順により、品質検査を終了する。 In the next step S13, it is determined whether the measured shear wave velocity Vs value is equal to or greater than the Vs,spe determined in step S4 above. If it is equal to or greater than Vs,spe, it is expected that the strength of the liquefied soil in situ will be equal to or greater than the design standard strength Fc. Therefore, if the measured Vs value is equal to or greater than Vs,spe, it is determined to be a pass, and the process is terminated (Yes in step S13). On the other hand, if the measured Vs value is less than Vs,spe (No in step S13) and the material age at the time of measurement is less than 28 days (Yes in step S16), the process returns to step S12, and the shear wave velocity Vs is measured again at a later date. On the other hand, if the measured Vs value is less than Vs,spe (No in step S13) and the material age at the time of measurement is 28 days or more (No in step S16), the poured area that is already lacking in strength is excavated (step S17), the manufacturing method and composition are reviewed (step S18), and then the process returns to step S5. A drilling core may be used to measure the shear wave velocity Vs value. In this case, a drilling core is collected and Vs-QUIC is performed on the collected core. The quality inspection is completed by the above procedure.
図３は、本実施の形態を適用して施工された流動化処理土の一軸圧縮強さの深度分布例である。この図に示されるように、施工された流動化処理土は、全深度にわたり設計基準強度を上回る強度を有していると判断できる。 Figure 3 shows an example of the depth distribution of the unconfined compressive strength of liquefied treated soil constructed using this embodiment. As shown in this figure, it can be determined that the constructed liquefied treated soil has strength that exceeds the design standard strength throughout the entire depth.
したがって、本実施の形態によれば、流動化処理土の配合計画時に材料分離抵抗性を高める粘度調整を行うことで、強度の不安定性を回避することができる。また、受け入れ検査時における未固結状態の流動化処理土にＣＷ－ＱＵＩＣを適用することで、固化材が十分添加されているか否かなどの施工品質を短時間（例えば１時間）で判定することができる。 Therefore, according to this embodiment, strength instability can be avoided by adjusting the viscosity to increase the resistance to material separation when planning the mix of liquefied treated soil. In addition, by applying CW-QUIC to liquefied treated soil in an unconsolidated state at the time of acceptance inspection, construction quality, such as whether or not sufficient solidification material has been added, can be determined in a short time (for example, one hour).
また、現場打設時の粘度測定とＣＷ－ＱＵＩＣによって、粘度または固化材量の過不足が判明した場合は、直ちに製造方法と配合計画を見直し、固まらないうちに流動化処理土の再施工が可能である。 In addition, if viscosity measurements during on-site pouring and CW-QUIC reveal an excess or deficiency in viscosity or amount of solidifying material, the manufacturing method and mix plan can be immediately reviewed, and the liquefied treated soil can be reapplied before it hardens.
流動化処理土が固化した後に、原位置にてＶｓ－ＱＵＩＣを実施することで、原位置で発現している強度を直接評価することができる。従来の製造時あるいは打設時の吐出口から採取したモールド供試体の２８日材齢時の圧縮試験と比較して、品質検査に要する時間を大幅に短縮でき、施工品質を早期に判断することができる。 By carrying out Vs-QUIC in situ after the liquefied soil has solidified, it is possible to directly evaluate the strength exhibited in situ. Compared to conventional compression tests conducted on molded specimens taken from the discharge port during production or pouring at 28 days of age, the time required for quality inspection can be significantly reduced, allowing for an early assessment of construction quality.
以上説明したように、本発明に係る流動化処理土の品質管理方法によれば、土質材料とセメント系固化材と水とを含有するとともに、地盤に打設して施工される流動化処理土の施工品質を管理するための方法であって、流動化処理土の配合計画の際に、土質材料の細粒分含有率またはセメント系固化材の添加量を調整して、流動化処理土の粘度を材料分離抵抗性を高める所定の範囲内に予め調整するステップと、施工直前の未固結状態の流動化処理土を採取するステップと、採取した流動化処理土の粘度を測定し、測定した粘度が所定の範囲内であるか否かを判定するステップと、採取した流動化処理土に含まれるセメント系固化材量または水に対するセメント系固化材の配合比率を推定し、推定したセメント系固化材量または配合比率が、設計基準強度に基づいて設定した所定の範囲内であるか否かを判定するステップと、施工後の固結状態の流動化処理土のせん断波速度を測定し、測定したせん断波速度が、設計基準強度に基づいて設定した所定の範囲内であるか否かを判定するステップとを有するので、流動化処理土の配合時に材料分離抵抗性を高める粘度調整を行うことで、強度の不安定性を回避することができる。 As explained above, the quality control method for liquefied treated soil according to the present invention is a method for controlling the construction quality of liquefied treated soil that contains soil material, cement-based solidification material, and water and is poured into the ground for construction, and includes the steps of: when planning the mix of the liquefied treated soil, adjusting the fine particle content of the soil material or the amount of cement-based solidification material to be added to adjust the viscosity of the liquefied treated soil in advance to within a predetermined range that enhances resistance to material separation; sampling the liquefied treated soil in an unconsolidated state immediately before construction; and measuring the viscosity of the sampled liquefied treated soil and determining whether the measured viscosity is within the predetermined range. The method includes the steps of: estimating the amount of cement-based solidification material contained in the collected liquefied treated soil or the mixing ratio of the cement-based solidification material to water, and determining whether the estimated amount of cement-based solidification material or the mixing ratio is within a predetermined range set based on the design standard strength; and measuring the shear wave velocity of the liquefied treated soil in a solidified state after construction, and determining whether the measured shear wave velocity is within a predetermined range set based on the design standard strength. Therefore, by adjusting the viscosity to increase the resistance to material separation when mixing the liquefied treated soil, it is possible to avoid instability in strength.
また、本発明に係る他の流動化処理土の品質管理方法によれば、流動化処理土を酸で中和した際の初期のｐＨの時間変化特性を利用して、セメント系固化材量または配合比率を推定するので、迅速かつ安価にセメント系固化材量または配合比率を推定することができる。 In addition, according to another quality control method for liquefied treated soil of the present invention, the amount or mix ratio of cement-based solidification material is estimated by utilizing the time change characteristics of the initial pH when the liquefied treated soil is neutralized with acid, so that the amount or mix ratio of cement-based solidification material can be estimated quickly and inexpensively.
また、本発明に係る他の流動化処理土の品質管理方法によれば、流動化処理土の施工に先立って、土質材料と、セメント系固化材と、水とを混合して配合試験を行うステップをさらに有し、この配合試験は、流動化処理土の供試体についてセメント系固化材添加量と材齢を変えながらせん断波速度の測定と圧縮強度の試験を行い、セメント系固化材添加量と圧縮強度の関係、および、せん断波速度と圧縮強度の関係を取得するステップと、取得した関係に基づいて、所定の設計基準強度に対応するセメント系固化材添加量およびせん断波速度を設定するステップとを含むので、所定の設計基準強度の発現に必要なセメント系固化材添加量およびせん断波速度を精度よく把握することができる。 In addition, another quality control method for liquefied treated soil according to the present invention further includes a step of performing a mix test by mixing soil material, cement-based solidification material, and water prior to construction of the liquefied treated soil. This mix test includes a step of measuring shear wave velocity and testing compressive strength while changing the amount of cement-based solidification material added and the material age for a specimen of liquefied treated soil, obtaining the relationship between the amount of cement-based solidification material added and the compressive strength, and the relationship between shear wave velocity and compressive strength, and a step of setting the amount of cement-based solidification material added and the shear wave velocity corresponding to a specified design standard strength based on the obtained relationship. Therefore, the amount of cement-based solidification material added and the shear wave velocity required to realize the specified design standard strength can be accurately grasped.
以上のように、本発明に係る流動化処理土の品質管理方法は、埋戻し材料などに用いられる流動化処理土の施工管理に有用であり、特に、流動化処理土における強度の不安定性を回避するのに適している。 As described above, the quality control method for liquefied treated soil according to the present invention is useful for managing the construction of liquefied treated soil used as backfill material, etc., and is particularly suitable for avoiding strength instability in liquefied treated soil.
Claims (3)
流動化処理土の配合計画の際に、土質材料の細粒分含有率またはセメント系固化材の添加量を調整して、流動化処理土の粘度を材料分離抵抗性を高める所定の範囲内に予め調整するステップと、施工直前の未固結状態の流動化処理土を採取するステップと、採取した流動化処理土の粘度を測定し、測定した粘度が所定の範囲内であるか否かを判定するステップと、採取した流動化処理土に含まれるセメント系固化材量または水に対するセメント系固化材の配合比率を推定し、推定したセメント系固化材量または配合比率が、設計基準強度に基づいて設定した所定の範囲内であるか否かを判定するステップと、施工後の固結状態の流動化処理土のせん断波速度を測定し、測定したせん断波速度が、設計基準強度に基づいて設定した所定の範囲内であるか否かを判定するステップとを有することを特徴とする流動化処理土の品質管理方法。 A method for managing the quality of liquefied treated soil which contains a soil material, a cement-based solidification material, and water and is poured into the ground, comprising:
A quality control method for liquefied treated soil, comprising the steps of: adjusting the fine particle content of the soil material or the amount of cement-based solidification material added when planning the mixture composition of liquefied treated soil, to adjust in advance the viscosity of the liquefied treated soil within a predetermined range that increases resistance to material separation; sampling the unconsolidated liquefied treated soil immediately before construction; measuring the viscosity of the sampled liquefied treated soil and determining whether the measured viscosity is within the predetermined range; estimating the amount of cement-based solidification material contained in the sampled liquefied treated soil or the mixture ratio of the cement-based solidification material to water, and determining whether the estimated amount of cement-based solidification material or mixture ratio is within a predetermined range set based on the design standard strength; and measuring the shear wave velocity of the liquefied treated soil in a solidified state after construction, and determining whether the measured shear wave velocity is within a predetermined range set based on the design standard strength.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| JP2021113726A JP7614039B2 (en) | 2021-07-08 | 2021-07-08 | Quality control method for liquefied treated soil |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002180453A (en) | 2000-12-15 | 2002-06-26 | Neo Knead:Kk | Mixing rate confirming method for land forming body material in soil improvement construction method |
| JP2004044328A (en) | 2002-07-16 | 2004-02-12 | Kumagai Gumi Co Ltd | Method for controlling compounding ratio of soil mortar |
| JP2009001981A (en) | 2007-06-19 | 2009-01-08 | Shimizu Corp | Ground quality inspection method |
| JP2019019471A (en) | 2017-07-12 | 2019-02-07 | 清水建設株式会社 | Strength estimation method, compression strength estimation device, compression strength determination device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002180453A (en) | 2000-12-15 | 2002-06-26 | Neo Knead:Kk | Mixing rate confirming method for land forming body material in soil improvement construction method |
| JP2004044328A (en) | 2002-07-16 | 2004-02-12 | Kumagai Gumi Co Ltd | Method for controlling compounding ratio of soil mortar |
| JP2009001981A (en) | 2007-06-19 | 2009-01-08 | Shimizu Corp | Ground quality inspection method |
| JP2019019471A (en) | 2017-07-12 | 2019-02-07 | 清水建設株式会社 | Strength estimation method, compression strength estimation device, compression strength determination device |
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