JP7055515B1 - Method for estimating long-term strength of chemical-improved soil - Google Patents
Method for estimating long-term strength of chemical-improved soil Download PDFInfo
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- 230000007774 longterm Effects 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000002689 soil Substances 0.000 title claims abstract description 52
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 195
- 239000000463 material Substances 0.000 claims abstract description 89
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 71
- 238000002347 injection Methods 0.000 claims abstract description 46
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- 230000006872 improvement Effects 0.000 claims abstract description 17
- 238000013461 design Methods 0.000 claims abstract description 15
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- 230000007423 decrease Effects 0.000 claims description 21
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- 238000010276 construction Methods 0.000 claims description 5
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- 235000019353 potassium silicate Nutrition 0.000 description 4
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 4
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Abstract
【課題】薬液注入工法により改良土の長期的な強度の検証を効率良く、経済的に行うことを目的として、恒久グラウトにおいては恒久的な品質確保を確認でき、また中性・酸性系注入材においては長期強度を推定することができる薬液改良土の長期強度の推定方法を提供する。【解決手段】活性シリカコロイド系、活性複合シリカ系、または中性・酸性系のグラウトによるサンドゲルの長期強度を推定する方法として、独立変数を養生日数を固化時間で除した正規化材令（日/日）と定義し、グラウトに関する設計パラメータを従属変数として、回帰分析によって長期強度を推定する。設計パラメータとしては、一軸圧縮強さ、液状化強度、変形係数、粘着力などを用いることができる。また、供用期間が限定される構造物に関し、推定された長期強度に基づいて、所定の期間改良効果が確保できることを確認し、注入材の配合を決定する。【選択図】図１１PROBLEM TO BE SOLVED: To confirm permanent quality assurance in permanent grout for the purpose of efficiently and economically verifying the long-term strength of improved soil by a chemical injection method, and a neutral / acidic injection material. Provides a method for estimating the long-term strength of chemical-improved soil, which can estimate the long-term strength. SOLUTION: As a method for estimating the long-term strength of sandgel by active silica colloidal type, active composite silica type, or neutral / acidic grout, the normalization material ordinance (day) in which the independent variable is divided by the curing time by the solidification time is used. / Day), and the long-term intensity is estimated by regression analysis with the design parameters related to grout as the dependent variable. As design parameters, uniaxial compressive strength, liquefaction strength, deformation coefficient, adhesive strength and the like can be used. Further, for the structure having a limited service period, it is confirmed that the improvement effect for a predetermined period can be secured based on the estimated long-term strength, and the compounding of the injection material is determined. [Selection diagram] FIG. 11
Description
本発明は薬液注入工法により改良された土の長期的強度を推定する方法であり、特に液状化対策や耐震補強工事などを目的とする地盤改良工事において適切な注入材の選定および配合を決定することができる薬液改良土の長期強度の推定方法に関するものである。 The present invention is a method for estimating the long-term strength of soil improved by the chemical injection method, and determines the selection and formulation of an appropriate injection material especially in ground improvement work for the purpose of liquefaction countermeasures and seismic retrofitting work. It relates to a method for estimating the long-term strength of chemical-improved soil that can be used.
耐久性を期待する薬液注入工法による地盤改良工事では、設計強度に対して安全率を乗じた室内目標強度が設定されており、材令２８日における強度をもって配合を決定している。 In the ground improvement work by the chemical injection method, which is expected to be durable, the indoor target strength is set by multiplying the design strength by the safety factor, and the blending is decided based on the strength as of the 28th day of the material decree.
しかし、これらの工事を対象とする構造物の供用期間は数年から数十年であることより、供用期間中における改良効果の持続性を予測する手法が重要となる。 However, since the service period of the structure for these works is several years to several decades, a method for predicting the sustainability of the improvement effect during the service period is important.
このような長期強度の予測方法としては、薬液注入材により固化した砂を高温にて養生するアレニウス法によるものが提案されている。このアレニウス法は反応速度論から求められ、速度定数の対数が絶対温度の逆数に比例することに基づいたものであり、劣化の要因は熱のみによって生じるものとされており、複合劣化に対応できないことが指摘されている。 As a method for predicting such long-term strength, a method by the Arrhenius method in which sand solidified by a chemical injection material is cured at a high temperature has been proposed. This Arrhenius method is obtained from reaction kinetics and is based on the fact that the logarithm of the rate constant is proportional to the reciprocal of the absolute temperature. It has been pointed out.
なお、薬液単体の固化は液温が高いものほど短くなるが、これは、注入材中のシリカ粒子のブラウン運動が活発になり、ＤＬＶＯ理論におけるエネルギー障壁を超えやすくなるためと考えられる。また、既往の研究によると薬液改良土の強度低下の要因として、一度ゲル化したシリカの溶解や過剰な体積収縮が指摘されている。 The solidification of the chemical substance alone becomes shorter as the liquid temperature increases, which is considered to be because the Brownian motion of the silica particles in the injection material becomes active and it becomes easier to overcome the energy barrier in the DLVO theory. In addition, according to previous studies, it has been pointed out that the dissolution of silica once gelled and the excessive volume shrinkage are the causes of the decrease in the strength of the chemical solution-improved soil.
従って、アレニウス法は複合劣化に対応できないことより、シリカの溶脱や体積変化が劣化の要因とされている注入材に対する対応性が低いことから、新たな方法の検討が望まれている。 Therefore, since the Arrhenius method cannot cope with composite deterioration and has low compatibility with the injectable material in which silica leaching and volume change are considered to be factors of deterioration, it is desired to study a new method.
液状化対策を目的とした地盤改良工法の一つとして、活性シリカコロイドを主剤とする溶液型注入材を用いた薬液注入工法が一般的に知られている。薬液注入工法による液状化対策では、地震時に生じる最大せん断応力比に対して十分な液状化強度比となるように地盤の改良強度が設定される。 As one of the ground improvement methods for liquefaction countermeasures, a chemical injection method using a solution-type injection material containing active silica colloid as a main agent is generally known. In the liquefaction countermeasures by the chemical injection method, the improved strength of the ground is set so that the liquefaction strength ratio is sufficient for the maximum shear stress ratio generated at the time of an earthquake.
このような工事においては液状化強度と一軸圧縮強さの関係より材令２８日における一軸圧縮強さを設計強度とした配合試験が実施されている（非特許文献１）。しかし、長期的に改良強度が増加する場合があるため、材令２８日で決定した配合が過剰となる場合もある。 In such construction, a compounding test is carried out with the uniaxial compressive strength as the design strength on the 28th of the material age due to the relationship between the liquefaction strength and the uniaxial compressive strength (Non-Patent Document 1). However, since the improved strength may increase in the long term, the formulation determined on the 28th day of the material age may be excessive.
また、近年では改良強度が継時的に低下する場合でも、その値は一定値に収束する特性を考慮し、構造物の供用期間中、性能を満たすように配合を決定する設計手法が提案されている（特許文献１）。 Further, in recent years, a design method has been proposed in which the composition is determined so as to satisfy the performance during the service period of the structure, considering the characteristic that the value converges to a constant value even when the improved strength decreases with time. (Patent Document 1).
なお現在、耐久性が期待できる注入材としては、水ガラスを主剤とする中性・酸性系のものと、活性シリカコロイドに反応剤を添加した活性シリカコロイド系、活性シリカコロイドと特殊水ガラスを主剤とし、これに反応剤を添加した活性複合シリカ系の３タイプのものがある。なお、中性・酸性系のものでは水ガラスのモル比、活性複合シリカ系では活性シリカコロイドと特殊水ガラスの比率など、注入材の配合は数種類に及び、体積収縮量や一軸圧縮強さなどの固化特性に違いが見られる（非特許文献２）。 Currently, as injection materials that can be expected to be durable, neutral / acidic materials with water glass as the main ingredient, active silica colloids with a reactant added to active silica colloid, active silica colloid and special water glass are used. There are three types of active composite silica-based ones in which a reactant is added to the main agent. There are several types of injection materials, such as the molar ratio of water glass for neutral / acidic type and the ratio of active silica colloid and special water glass for active composite silica type, such as volume shrinkage and uniaxial compressive strength. There is a difference in the solidification characteristics of silica (Non-Patent Document 2).
また、これらの注入材は基本的にシリカ濃度によって改良強度が増減するが、その割合は砂の諸特性によって異なることが知られている（非特許文献３）。さらに、養生に伴う改良強度の増減も注入材のタイプや濃度と砂の諸特性によって異なる傾向にある（非特許文献４）。 Further, it is known that the improved strength of these injection materials basically increases or decreases depending on the silica concentration, but the ratio varies depending on various characteristics of sand (Non-Patent Document 3). Further, the increase / decrease in the improved strength with curing tends to differ depending on the type and concentration of the injection material and various characteristics of sand (Non-Patent Document 4).
このように、注入材と砂の組み合わせによって得られる改良土の改良効果と長期特性は多種多様であるため、適切な注入材タイプの選定や配合の決定を行うためには、薬液注入工法による改良効果の長期予測が重要となっている。 In this way, the improvement effect and long-term characteristics of the improved soil obtained by the combination of the injection material and sand are diverse. Therefore, in order to select an appropriate injection material type and determine the composition, the improvement by the chemical injection method is used. Long-term prediction of effects is important.
本発明は従来技術における上述のような課題の解決を図ったものであり、薬液注入工法により改良土の長期的な強度の検証を効率良く、経済的に行うことができ、恒久グラウトにおいては恒久的な品質確保を確認でき、また中性・酸性系注入材においては長期強度を推定することができる薬液改良土の長期強度の推定方法を提供することを目的とする。 The present invention is intended to solve the above-mentioned problems in the prior art, and it is possible to efficiently and economically verify the long-term strength of the improved soil by the chemical injection method, and the permanent grout is permanent. It is an object of the present invention to provide a method for estimating the long-term strength of chemical-improved soil, which can confirm the quality assurance and can estimate the long-term strength of neutral / acidic injection materials.
本発明の対象は中性・酸性系グラウト、活性シリカ系グラウト、活性複合シリカ系グラウトであり、シリカの溶脱による継時的な改良強度の低下が生じないものである。また、本発明に関わる薬液注入材による改良土の長期強度の推定方法は、注入材そのもの（ヒドロゲル）の固化特性を把握した後、その特性より注入材で固化した砂（サンドゲル）の長期強度を予測するものである。 The objects of the present invention are neutral / acidic grouts, active silica grouts, and active composite silica grouts, and the improvement strength does not gradually decrease due to leaching of silica. Further, in the method for estimating the long-term strength of the improved soil using the chemical injection material according to the present invention, after grasping the solidification characteristics of the injection material itself (hydrogel), the long-term strength of the sand (sand gel) solidified by the injection material is determined from the characteristics. It is a prediction.
本発明は、このような活性シリカコロイド系、活性複合シリカ系、または中性・酸性系のグラウトによるサンドゲルの長期強度の推定方法であり、独立変数を養生日数を固化時間で除した正規化材令（日/日）と定義し、前記グラウトに関する設計パラメータを従属変数として、回帰分析によって長期強度を推定することを特徴とする。 The present invention is a method for estimating the long-term strength of a sand gel using such an active silica colloidal system, an active composite silica system, or a neutral / acidic grout, and is a normalizing material in which the independent variable is divided by the curing time by the solidification time. It is defined as an order (day / day), and is characterized in that the long-term intensity is estimated by regression analysis with the design parameters related to the grout as the dependent variable.
設計パラメータとしては、一軸圧縮強さ、液状化強度、変形係数、または粘着力などが用いられる。 As design parameters, uniaxial compressive strength, liquefaction strength, deformation coefficient, adhesive strength and the like are used.
また、設計パラメータとＳ波速度の関係を求め、これを従属関数とし、回帰分析による長期材令におけるＳ波速度から強度を推定することができる。 In addition, the relationship between the design parameter and the S wave velocity can be obtained, and this can be used as a dependent function to estimate the intensity from the S wave velocity in the long-term decree by regression analysis.
本発明の薬液改良土の長期強度の推定方法において、長期強度の予測は、独立変数としての正規化材令が１日/日～５００日/日、または５００日/日より大となる期間の増減より回帰式を決定することができる。 In the method for estimating the long-term strength of the chemical-improved soil of the present invention, the prediction of the long-term strength is for a period in which the normalized material ordinance as an independent variable is greater than 1 day / day to 500 days / day or 500 days / day. The regression equation can be determined from the increase / decrease.
また、本発明の薬液改良土の設計方法は、上述の薬液改良土の長期強度の推定方法を用い、供用期間が限定される構造物に関して、所定の期間改良効果が確保できることを確認し、注入材の配合を決定することを特徴とし、本発明の設計方法を用いて調合した活性シリカコロイド系、活性複合シリカ系、または中性・酸性系のグラウトを地盤に注入して地盤改良を行うことができる。 Further, the method for designing the chemical solution-improved soil of the present invention uses the above-mentioned method for estimating the long-term strength of the chemical solution-improved soil, confirms that the improvement effect for a predetermined period can be secured for the structure having a limited service period, and injects the soil. The soil is improved by injecting active silica colloidal, active composite silica, or neutral / acidic grout prepared by the design method of the present invention into the ground, which is characterized by determining the composition of the material. Can be done.
また、土中ゲルタイムを基準としたサンドゲルの長期強度を予測することにより、構造物の供用期間中に要求される性能を満たすことを確認して薬液を注入することができる。 Further, by predicting the long-term strength of the sand gel based on the soil gel time, it is possible to confirm that the performance required during the service period of the structure is satisfied and inject the chemical solution.
なお、より具体的には、ヒドロゲルの固化特性の把握は、例えば、次の手段によって行うことができる。
1. シリカ濃度やコロイド含有率を一律とするが、注入材の固化時間GTHG（日）が異なる配合を設定する。
2. GTHGが異なる条件にて材令（日）とヒドロゲルの体積変化率および一軸圧縮強さを求める。
3. 体積変化および一軸圧縮強さが収束する材令（日）を確認する。
4. 材令dayをGTHGで除した値を独立変数とし、体積変化率および一軸圧縮強さを従属変数とした正規化材令dayH（日/日）と、体積変化率と一軸圧縮強さの関係を求める。
5. シリカ濃度やコロイド含有率が異なる配合にて1～4に記載の方法により幅広いヒドロゲルの固化特性を把握する。
More specifically, the solidification property of hydrogel can be grasped by, for example, the following means.
1. Set the formulation with a uniform silica concentration and colloid content, but with different solidification times GT HG (days) for the injection material.
2. Obtain the volume change rate and uniaxial compressive strength of the hydrogel and the material age (day) under different conditions for GT HG .
3. Confirm the material ordinance (day) at which the volume change and uniaxial compressive strength converge.
4. Normalized material order day H (day / day) with the volume change rate and uniaxial compressive strength as the dependent variables, and the volume change rate and uniaxial compressive strength, with the value obtained by dividing the material date by GT HG as the independent variable. Find the relationship.
5. Understand the solidification characteristics of a wide range of hydrogels by the methods described in 1 to 4 with formulations having different silica concentrations and colloidal contents.
次に、サンドゲルの長期強度特性の推定方法は次の手段によることができる。
1. 土中に浸透・混合された状態（サンドゲル）における注入材の固化時間GTSGはGTHGと比較して砂の成分によって短くなるため、GTSGを測定する。
2. 材令dayをGTSGで除した値をサンドゲルの正規化材令daySと定義し、daySが1～500以上におけるサンドゲルの強度特性を求め、daySを独立変数とし、強度特性を従属変数とする関係図を作成する。
3. 2において強度特性が常に増加傾向にある場合、対数または双曲線などの近似曲線を求める。
4. 2において強度特性が増加したのち、低下傾向に圧場合、低下傾向にある区間のデータを用い、対数または双曲線などの近似曲線を求める。
5. 3または4にて求めた近似曲線の独立変数に地盤改良の効果を期待する期間（日）や構造物の供用期間（日）にGTSGを乗じた値を与え、長期強度を予測する。
Next, the method for estimating the long-term strength characteristics of sandgel can be as follows.
1. Since the solidification time of the injection material in the state of being infiltrated and mixed in the soil (sand gel) is shorter than that of GT HG due to the sand component, GT SG is measured.
2. The value obtained by dividing the material day by GT SG is defined as the normalization material day S of sandgel, the strength characteristics of sandgel are obtained when day S is 1 to 500 or more, and day S is set as an independent variable and the strength characteristics are set. Create a relationship diagram as a dependent variable.
If the intensity characteristics are constantly increasing in 3.2, find an approximate curve such as a logarithm or a hyperbola.
If the strength characteristic increases in 4.2 and then the pressure tends to decrease, the approximate curve such as a logarithm or a hyperbola is obtained using the data of the section that tends to decrease.
5. Give the independent variable of the approximate curve obtained in 3 or 4 the value obtained by multiplying the period (day) when the effect of ground improvement is expected or the service period (day) of the structure by GT SG , and predict the long-term strength. ..
なお、前述のサンドゲルの長期強度特性の推定方法は、実際に供試体を破壊することにその物性を得ているが、サンドゲルの作製本数および供試体作製時のバラツキを低減する目的で、非破壊による次の手順も有効である。
1. 一軸圧縮強さや変形係数、粘着力などの強度特性とせん断波速度の関係を求め、検量線を作成する。
2. 材令とせん断波速度の関係を求める。
3. サンドゲルの長期強度特性の推定方法と同様に、せん断波速度の長期予測をする。
予測したせん断波速度から、1で求めた検量線を用い長期強度特性を導く。
In addition, although the above-mentioned method for estimating the long-term strength characteristics of the sand gel is obtained by actually destroying the specimen, it is non-destructive for the purpose of reducing the number of sand gels produced and the variation during the production of the specimen. The following procedure by is also effective.
1. Obtain the relationship between the shear wave velocity and the strength characteristics such as uniaxial compression strength, deformation coefficient, and adhesive force, and create a calibration curve.
2. Find the relationship between the material age and the shear wave velocity.
3. Long-term prediction of shear wave velocity is performed in the same way as the estimation method of long-term strength characteristics of sandgel.
From the predicted shear wave velocity, the long-term strength characteristics are derived using the calibration curve obtained in 1.
恒久グラウトとして使用される活性シリカ系および活性複合シリカ系グラウトにおいて、長期的に強度が増加する場合、適切な材令における強度をもって配合を決定することにより、シリカ濃度を低減でき、経済的な地盤改良を実施することができる。 In active silica-based and active composite silica-based grout used as permanent grout, when the strength increases in the long term, the silica concentration can be reduced and the ground is economical by determining the composition with the strength according to the appropriate material age. Improvements can be made.
一方、仮設工事を目的として使用されてきた中性・酸性系グラウトでは、長期的な強度を予測し、これが構造物の供用期間中に期待する強度特性を満足することを確認することによって、液状化対策や耐震補強などの工事に適用することができるようになる。従って、従来では恒久グラウトを使用してきた工事において、中性・酸性系グラウトの使用が可能となり、経済的な地盤改良工事を実施することができるようになる。 On the other hand, neutral and acidic grout, which has been used for temporary construction, is liquid by predicting long-term strength and confirming that it satisfies the expected strength characteristics during the service period of the structure. It will be possible to apply it to construction work such as liquefaction measures and seismic retrofitting. Therefore, in the construction work in which the permanent grout has been used in the past, the neutral / acidic grout can be used, and the economical ground improvement work can be carried out.
なお、この長期強度の確認方法において、非破壊試験を実施することにより、一軸圧縮試験や三軸圧縮試験などの力学試験を実施するのと比較して、供試体作製本数やバラツキを低減することができ、試験実施に関する費用を削減することができる。 In this long-term strength confirmation method, by conducting a non-destructive test, the number of specimens to be manufactured and variations should be reduced compared to conducting mechanical tests such as uniaxial compression test and triaxial compression test. And the cost of conducting the test can be reduced.
本発明では初めに注入材のゲルタイムGTHGを確認する。図１は酸性系シリカグラウトにおける注入材のpHとゲルタイムGTHGの関係である。ゲルタイムGTHGは同一のシリカ濃度であれば、pHの低下に伴い長くなる傾向にある。また、同一のpHの場合では、シリカ濃度が高いものほどゲルタイムGTHGは短くなる傾向にある。 In the present invention, the gel time GT HG of the injection material is first confirmed. FIG. 1 shows the relationship between the pH of the injection material and the gel time GT HG in the acidic silica grout. Geltime GT HG tends to become longer as the pH decreases if the silica concentration is the same. In addition, at the same pH, the higher the silica concentration, the shorter the gel time GT HG tends to be.
このような傾向は、活性シリカ系や活性複合シリカ系グラウトでも同様であるが、活性複合シリカ系グラウトでは注入材に含まれるコロイド含有率が高いものほど、同一のpHおよびシリカ濃度におけるゲルタイムは長くなる傾向にある。 This tendency is the same for active silica-based and active composite silica-based grouts, but in active composite silica-based grouts, the higher the colloid content contained in the injection material, the longer the gel time at the same pH and silica concentration. It tends to be.
このようにゲルタイムGTHGを確認したのち、ゲルタイムGTHGの異なるヒドロゲルを作製し、体積変化率と一軸圧縮強さを測定する。溶液注入材のゲル化メカニズムはシリカ粒子表面のシラノール基が重合しながら三次元的に高分子化し、流動性を失うことによるものであり、この反応はゲル化後も継続されるためヒドロゲルに体積変化が生じる。 After confirming the gel time GT HG in this way, hydrogels with different gel time GT HG are prepared, and the volume change rate and uniaxial compressive strength are measured. The gelation mechanism of the solution injection material is due to the fact that the silanol groups on the surface of the silica particles polymerize three-dimensionally and lose their fluidity, and this reaction continues even after gelation, so the volume of the hydrogel is increased. Changes occur.
図２はヒドロゲルの材令と体積変化率の関係であるが、体積変化率の負の値はヒドロゲルの収縮を、正の値は膨張を表すものである。ヒドロゲルの体積収縮はゲル化後に生じ、同一の材令ではゲルタイムGTHGが短いものほど大きくなる傾向にある。しかし、最終的な体積収縮率はゲルタイムGTHGに関わらずほぼ同程度となる傾向を示す。 FIG. 2 shows the relationship between the hydrogel's age and the volume change rate. A negative value of the volume change rate indicates the contraction of the hydrogel, and a positive value indicates the expansion. The volume shrinkage of hydrogel occurs after gelation, and the shorter the gel time GT HG is, the larger the volume tends to be. However, the final volume shrinkage tends to be about the same regardless of the gel time GT HG .
図３はヒドロゲルの材令と一軸圧縮強さの関係であるが、一軸圧縮強さは体積変化率の継時的な傾向と概ね一致する傾向にある。 FIG. 3 shows the relationship between the age of the hydrogel and the uniaxial compressive strength, and the uniaxial compressive strength tends to be in good agreement with the temporal tendency of the volume change rate.
なお、図４はゲルタイムGTHGを180minに設定した酸性系グラウトの材令と体積変化率および一軸圧縮強さの関係であるが、同一の材令における一軸圧縮強さはシリカ濃度が高いものほど大きい傾向にあり、最終的な強度も同様である。一方、体積変化率はシリカ濃度に関わらず概ね同程度となる傾向を示す。このような傾向は活性複合シリカ系グラウトでも同様の傾向を示すが、これらの場合、コロイド含有率が高くなるほど一軸圧縮強さと体積収縮率は小さくなる傾向にある。 In addition, FIG. 4 shows the relationship between the volume change rate and the uniaxial compressive strength of the acidic grout with the gel time GT HG set to 180 min. It tends to be larger, and so is the final strength. On the other hand, the volume change rate tends to be about the same regardless of the silica concentration. Such a tendency shows the same tendency in the active composite silica grout, but in these cases, the uniaxial compression strength and the volume shrinkage tend to decrease as the colloid content increases.
図５は図２の材令dayをゲルタイムGTHGで除した値を独立変数とし、体積変化率および一軸圧縮強さを従属変数とした正規化材令dayH（日/日）と体積変化率の関係であり、図６は図３の材令を正規化した正規化材令と一軸圧縮強さの関係である。 In FIG. 5, the normalized material ordinance day H (day / day) and the volume change rate, in which the value obtained by dividing the material ordinance day in Fig. 2 by the gel time GT HG is the independent variable and the volume change rate and the uniaxial compressive strength are the dependent variables. FIG. 6 shows the relationship between the normalized material ordinance obtained by normalizing the material ordinance of FIG. 3 and the uniaxial compressive strength.
体積変化は正規化材令が100～300（日/日）程度で収束値の８割程度となる。また、一軸圧縮強さも正規化材令が100～500（日/日）で収束値の８割程度となっている。従って、ゲルタイムGTHGが異なる条件でも正規化材令100～500（日/日）の継時的な挙動より、長期的なヒドロゲルの特性の材令に伴う変化について、近似曲線を用いることにより予測することは可能と言える。
The volume change is about 80% of the convergence value when the normalized material ordinance is about 100 to 300 (days / day). In addition, the uniaxial compression strength is about 80% of the convergence value when the normalized material ordinance is 100 to 500 (days / day). Therefore, even if the gel time GT HG is different, the change in the long-term hydrogel characteristics due to the material age is predicted by using the approximate curve from the temporal behavior of the normalized
図７はシリカ濃度Csが６％、ゲルタイムGTHGの酸性系シリカグラウト用い、固化した砂の一軸圧縮強さの経時変化である。なお、砂には最も粒径の小さい砂として豊浦砂を、最も粒径が大きい砂として珪砂５号を、粒径が中位のものとして珪砂６号を使用している。なお、ここで使用した砂はきれいな砂であり、炭酸カルシウムをほとんど含まないものであるため、土中ゲルタイムGTSGはヒドロゲルのゲルタイムGTHGと同程度の300minとなっている。 FIG. 7 shows the change over time in the uniaxial compressive strength of solidified sand using an acidic silica grout having a silica concentration of 6% and gel time GT HG . As the sand, Toyoura sand is used as the sand having the smallest particle size, silica sand No. 5 is used as the sand having the largest particle size, and silica sand No. 6 is used as the sand having a medium particle size. Since the sand used here is clean sand and contains almost no calcium carbonate, the soil gel time GT SG is 300 min, which is about the same as the hydrogel gel time GT HG .
いずれの砂においても一軸圧縮強さは増加したのち、低下する傾向を示すが、その値は一定値に収束する傾向にある。これは、図２及び図３に示したように、ヒドロゲルの体積変化率や一軸圧縮強さは継時的に一定値に収束する傾向があり、ヒドロゲルの反応が収束するとサンドゲルの強度特性も一定値に収束すると言える。 In all sands, the uniaxial compressive strength tends to increase and then decrease, but the value tends to converge to a constant value. This is because, as shown in FIGS. 2 and 3, the volume change rate and uniaxial compressive strength of the hydrogel tend to converge to a constant value over time, and when the reaction of the hydrogel converges, the strength characteristics of the sandgel also become constant. It can be said that it converges to the value.
図８は図７の材令を土中ゲルタイムGTSGで除した正規化材令とサンドゲルの一軸圧縮強さの関係であり、強度低下が発生した材令２８日（実材令）から正規化材令dayHが500（日/日）程度の範囲をプロットしている。ここで正規化材令を500（日/日）以上とした理由は、図５に示したようにヒドロゲル自身の体積変化が８０％完了していることによるものである。なお、曲線は正規化材令を独立変数とし、一軸圧縮強さを従属変数として累乗関数にて決定した近似曲線である。 FIG. 8 shows the relationship between the normalized material ordinance obtained by dividing the material ordinance of FIG. 7 by the soil gel time GT SG and the uniaxial compressive strength of the sand gel. The material normalization day H is plotted in the range of about 500 (days / day). Here, the reason why the normalized material ordinance is set to 500 (days / day) or more is that the volume change of the hydrogel itself is 80% completed as shown in FIG. The curve is an approximate curve determined by a power function with the normalized compressive strength as the independent variable and the uniaxial compressive strength as the dependent variable.
また、図９はシリカ濃度Csが１２％、土中ゲルタイムGTSGが300minにおける結果であるが、濃度が低い６％ではいずれの砂でも強度低下が見られたが、１２％においては豊浦砂に強度低下が見らえるものの珪砂６号および珪砂５号では強度低下が見られない。 In addition, Fig. 9 shows the results when the silica concentration C s was 12% and the soil gel time GT SG was 300 min. At 6%, where the concentration was low, the strength decreased in all sands, but at 12%, Toyoura sand. However, there is no decrease in strength in silica sand No. 6 and silica sand No. 5.
よって、図１０に示すように豊浦砂では強度低下が生じ始めた正規化養生日数から400（日/日）までで、珪砂６号と珪砂５号では養生初期より正規化材令500（日/日）以上の間で近似曲線を前述のとおり決定した。 Therefore, as shown in Fig. 10, in Toyoura sand, the number of normalized curing days from the beginning of the decrease to 400 (days / day), and in silica sand No. 6 and silica sand No. 5, the normalized material ordinance 500 (days / day) from the beginning of curing. (Day) The approximate curve was determined as described above.
このように決定した近似曲線を用い、材令300日（正規化養生材令1440（日/日）=300日/（300min/60min/24hour））の一軸圧縮強さを予測し、実測値との比較を行った。なお、ここでは実材令が１日～80日のデータを用い300日の強度を予測している。 Using the approximate curve determined in this way, predict the uniaxial compressive strength of 300 days of material ordinance (normalized curing material ordinance 1440 (day / day) = 300 days / (300min / 60min / 24hour)), and use the measured value. Was compared. Here, the actual material ordinance predicts the intensity of 300 days using the data of 1 to 80 days.
図１１は一軸圧縮強さの予測値と実測値の関係であるが、両者はおおむね１：１の線上にプロットされていることや、決定係数が高いことより、比較的精度よく長期強度を予測できていると言える。 FIG. 11 shows the relationship between the predicted value and the measured value of the uniaxial compressive strength. Both are plotted on a line of about 1: 1 and the coefficient of determination is high, so that the long-term strength is predicted relatively accurately. It can be said that it is done.
図１２は豊浦砂のサンドゲルの継時的な強度低下が生じたときのヒドロゲルの体積変化率と変形係数の関係である。なお、ここで示している注入材は酸性系シリカグラウトと活性シリカコロイド系グラウト、活性複合シリカ系グラウトであり、そのシリカ濃度は６％～２９％、コロイド含有率は０～１００％のものである。 FIG. 12 shows the relationship between the volume change rate and the deformation coefficient of the hydrogel when the strength of the sand gel of Toyoura sand decreases over time. The injection materials shown here are acidic silica grout, active silica colloidal grout, and active composite silica grout, the silica concentration being 6% to 29%, and the colloid content being 0 to 100%. be.
シリカ濃度が１２％のものでは、体積変化率が－２６％までは一軸圧縮強さが増加傾向にあるが、それ以上の体積変化が生じるとサンドゲルの一軸圧縮強さに継時的な低下が見られた。一方、シリカ濃度が６％のものでは体積変化率が－２２％まではサンドゲルの一軸圧縮強さは増加し、それ以上の体積変化が生じるとサンドゲルに経時的な強度低下が見られた。 When the silica concentration is 12%, the uniaxial compressive strength tends to increase until the volume change rate is -26%, but when the volume change further occurs, the uniaxial compressive strength of the sand gel decreases over time. It was seen. On the other hand, when the silica concentration was 6%, the uniaxial compressive strength of the sand gel increased until the volume change rate was -22%, and when the volume change further occurred, the strength of the sand gel decreased with time.
このようにサンドゲルの強度低下を生じさせる体積変化率の違いはヒドロゲルの変形係数に違いがあり、さらに図１３に示すように強度低下を生じさせるヒドロゲルの体積変化率と変形係数の閾値は砂の諸特性によって異なる傾向にある。 In this way, the difference in the volume change rate that causes the strength decrease of the sand gel is the difference in the deformation coefficient of the hydrogel, and as shown in FIG. 13, the threshold of the volume change rate and the deformation coefficient of the hydrogel that causes the strength decrease is that of sand. It tends to be different depending on various characteristics.
また、同図より、砂の種類が異なる場合でも、ヒドロゲルの体積が１５％程度収縮すると強度低下が生じることが示唆されており、最も体積変化が生じやすい酸性系シリカグラウトにおけるこの時の正規化材令は100（日/日）となっている。従って、この付近のサンドゲルの強度の増減を重点的に把握することにより、長期強度の予測の精度が向上する。 In addition, the figure suggests that even if the type of sand is different, the strength decreases when the volume of the hydrogel shrinks by about 15%, and the normalization at this time in the acidic silica grout where the volume change is most likely to occur. The material ordinance is 100 (day / day). Therefore, by focusing on the increase / decrease in the strength of the sand gel in the vicinity, the accuracy of long-term strength prediction is improved.
ここでは、現場砂を用いたサンドゲルに対し非破壊試験を実施することにより、供試体作製本数や試験数量を低減した方法について説明を行う。 Here, a method of reducing the number of specimens to be prepared and the number of test specimens by conducting a non-destructive test on sand gel using on-site sand will be described.
非破壊試験を用いる場合においても土中ゲルタイム測定を実施する。図１４はpHが異なるシリカ濃度が６％の注入材に砂を混合し、測定した土中ゲルタイムの測定結果である。なお、〇で示しているものは注入材そのもののpHとゲルタイムの関係である。土中ゲルタイムは注入材のゲルタイムと比較して、同一のpHであっても短くなる傾向を示す。これは砂に含まれるアルカリ成分の影響であり、土そのもののpHが高いものや、砂に貝殻などの炭酸カルシムが多く含まれるものほど顕著となる。 Even when using a non-destructive test, measure the gel time in the soil. FIG. 14 is a measurement result of soil gel time measured by mixing sand with an injection material having a different pH and a silica concentration of 6%. What is indicated by ◯ is the relationship between the pH of the injection material itself and the gel time. The soil gel time tends to be shorter than the gel time of the injection material even at the same pH. This is due to the influence of the alkaline component contained in the sand, and it becomes more remarkable when the pH of the soil itself is high or when the sand contains a large amount of carbonic acid calcium such as shells.
なお、土に混合された状態の注入材のpH（土中pH）とゲルタイム（土中ゲルタイム）の関係を図１５に示すが、土中の注入材は砂のpHや炭酸カルシウムなどの成分によって中性方向に移行し、ゲルタイムが短くなる傾向にある。従って、土中pHと土中ゲルタイムは一義的な関係となり、注入材そのもののpHとゲルタイムの関係の曲線上にプロットされる。つまり、土中における注入材の固化反応は砂の成分によって促進されることを示しているものであり、このことからも長期改良特性の予測に正規化材令を用いることの有効性が伺える。 The relationship between the pH of the injection material mixed in the soil (pH in the soil) and the gel time (gel time in the soil) is shown in FIG. 15. The injection material in the soil depends on the pH of the sand and components such as calcium carbonate. It tends to shift to the neutral direction and shorten the gel time. Therefore, the soil pH and the soil gel time have a unique relationship, and are plotted on the curve of the relationship between the pH of the injection material itself and the gel time. In other words, it is shown that the solidification reaction of the injection material in the soil is promoted by the sand component, and this also indicates the effectiveness of using the normalized material ordinance for predicting the long-term improvement characteristics.
このように土中ゲルタイムを確認したのち、シリカ濃度が異なるサンドゲルを作製し、非破壊試験としてベンダーエレメント法を用いＳ波速度を測定する。なお、作製する供試体本数は３～５本程度が望ましい。Ｓ波を測定した供試体に対し一軸圧縮試験を実施し、Ｓ波速度と一軸圧縮強さの検量線を求める。 After confirming the gel time in the soil in this way, sand gels having different silica concentrations are prepared, and the S wave velocity is measured using the bender element method as a non-destructive test. The number of specimens to be produced is preferably about 3 to 5. A uniaxial compression test is performed on the specimen on which the S wave is measured, and the calibration curve of the S wave velocity and the uniaxial compressive strength is obtained.
図１６はゲルタイムが12hour、シリカ濃度が３％～９％に設定された酸性系シリカグラウトによるサンドゲルにおけるシリカ濃度とＳ波速度の関係である。なお、土中ゲルタイムは３％で20min、６％で15min、９％では10minであった。 FIG. 16 shows the relationship between the silica concentration and the S wave velocity in the sand gel by the acidic silica grout in which the gel time is set to 12 hours and the silica concentration is set to 3% to 9%. The soil gel time was 20 min at 3%, 15 min at 6%, and 10 min at 9%.
図１７は図１６にて使用した供試体のシリカ濃度と一軸圧縮強さの関係である。一軸圧縮強さおよびＳ波速度はシリカ濃度の増加に伴い高くなる傾向にあるが、その増加割合は砂の粒径や密度によって異なるため、試料ごとに求める必要がある。 FIG. 17 shows the relationship between the silica concentration of the specimen used in FIG. 16 and the uniaxial compressive strength. The uniaxial compressive strength and the S wave velocity tend to increase as the silica concentration increases, but the rate of increase varies depending on the grain size and density of the sand, so it is necessary to obtain it for each sample.
このように求めたＳ波速度と一軸圧縮強さの関係を図１８に示す。この図を長期強度の予測に用いる検量線とする。 FIG. 18 shows the relationship between the S wave velocity obtained in this way and the uniaxial compressive strength. This figure is used as a calibration curve for predicting long-term intensity.
図１９は実材令が２８日までのサンドゲルの正規化材令とＳ波速度の関係である。シリカ濃度３％のＳ波速度は増加したのち、一定値に収束する傾向を示す。一方、シリカ濃度が６％と９％では、養生初期よりＳ波速度が低下しながら一定値に収束する傾向を示した。これらの傾向について近似曲線を求め、正規化材令で5000程度のＳ波速度を予測すると、３％で79.0m/sec、６％で103m/sec、９％では133m/secとなる。なお、ここで5000程度とした理由は、図５及び図６に示したように正規化材令が5000ではヒドロゲルの反応はほぼ終了していることより、土粒子間のヒドロゲルの反応も収束値に達していると判断できるからである。 FIG. 19 shows the relationship between the normalized material ordinance of Sandgel and the S wave velocity until the 28th of the actual material ordinance. After the S wave velocity with a silica concentration of 3% increases, it tends to converge to a constant value. On the other hand, when the silica concentrations were 6% and 9%, the S wave velocity tended to converge to a constant value while decreasing from the initial stage of curing. Approximate curves are obtained for these trends, and if the S wave velocity of about 5000 is predicted by the normalized material ordinance, it will be 79.0 m / sec at 3%, 103 m / sec at 6%, and 133 m / sec at 9%. The reason why the value is set to about 5000 here is that the hydrogel reaction between soil particles is also a convergent value because the hydrogel reaction is almost completed when the normalization material ordinance is 5000 as shown in FIGS. 5 and 6. This is because it can be judged that the value has been reached.
図２０は実際に材令150日まで測定した材令とＳ波速度の関係であるが、先ほどの予測値は実測値に対応する結果となっている。 FIG. 20 shows the relationship between the material age and the S wave velocity actually measured up to 150 days, and the predicted value mentioned earlier corresponds to the measured value.
また、図２１は同様の方法にて数種類の砂を対象に実施した試験結果であるが、予測値と実測値は１：１の関係にあることより本方法が妥当であることを確認できる。 Further, FIG. 21 shows the test results of several types of sand conducted by the same method, and it can be confirmed that this method is appropriate because the predicted value and the measured value have a 1: 1 relationship.
なお、長期材令における一軸圧縮強さを求める方法は、予測した長期材令におけるＳ波速度を図１８の近似曲線に与えることによって求めることができる。そして、予測した強度が供用期間中に必要な設計基準を満たしているかを判断し、適切な注入材の種類の選定や、濃度を決定する。 The method of determining the uniaxial compressive strength in the long-term aging can be obtained by giving the predicted S-wave velocity in the long-term aging to the approximate curve of FIG. Then, it is determined whether the predicted strength meets the required design criteria during the service period, the selection of an appropriate injection material type, and the concentration are determined.
なお、破壊試験にて長期試験を実施する場合、バラツキを考慮し、１材令で２～３本の供試体が必要となり、１０材令にて試験をする場合、２０～３０本の供試体の作製が必要となる。しかし、非破壊試験を用いることにより、検量線用として３本、非破壊試験用として予備を含め２本の計５本程度で実施することができ、大幅に供試体の作製本数を削減することが可能となる。 In addition, when conducting a long-term test in a destructive test, considering variations, 2 to 3 specimens are required for one material age, and when testing with 10 material age, 20 to 30 specimens are required. It is necessary to make. However, by using the non-destructive test, it is possible to carry out with a total of about 5 lines, 3 for the calibration curve and 2 for the non-destructive test, including the spare, and the number of specimens to be manufactured can be significantly reduced. Is possible.
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| KR100641842B1 (en) | 2005-06-24 | 2006-11-03 | 주식회사 스페이스 | Method for a semi-rigid pavement and cement milk for a semi-rigid pavement |
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