JP2005105577A - Quality standard determining method for fluidized treated earth - Google Patents
Quality standard determining method for fluidized treated earth Download PDFInfo
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本発明は、地盤の埋戻しなどに利用される流動化処理土の品質を決定するための流動化処理土の品質基準決定方法に関するものである。
The present invention relates to a method for determining the quality standard of fluidized soil for determining the quality of fluidized soil used for backfilling the ground.
流動化処理土とは、建設現場で発生する建設発生土や山砂などと、セメント系固化材とを混合して製造する、流動性の高い締め固め不要の充填材である。従来から流動化処理土は、地中構造物の周囲の狭隘な空間の埋戻し、地中空洞の充填に主に使われてきた。これは、このような空間が砂の締固めによる埋戻しが困難であり、それに替わる流動化処理土が流動性により確実に充填できるためである。 The fluidized soil is a highly fluidized filler that is produced by mixing construction-generated soil and mountain sand generated at a construction site with a cement-based solidified material. Conventionally, fluidized soil has been mainly used for backfilling narrow spaces around underground structures and filling underground cavities. This is because such a space is difficult to be backfilled by sand compaction, and fluidized soil that replaces it can be reliably filled with fluidity.
このような埋戻し材料に期待される性能は、深度方向の圧縮強度、地震時に生じる横荷重が作用した場合にもその体積を圧縮させることなく上載荷重を周辺地盤に均等に伝達する性能などである。
従来は、流動化処理土が上記したような性能を満たしているかどうかを確認するために一軸圧縮試験の結果のみを使用していた。しかし、流動化処理土は深さ方向に分布して配置されるにも関わらず、その品質基準値として使用される一軸圧縮強さは一定の値が適用されていた。現在、使用されている一軸圧縮強さの基準は200 kPa以上というものである。
また、従来の流動化処理土は、充填性、施工性を向上させるために、建設発生土の混合量を減らした密度の低い流動化処理土が多かった。密度の低い流動化処理土であっても、一軸圧縮強さは固化材のセメンテーションにより一定の固結力があれば確保できる。このため、密度の低い流動化処理土には、一軸圧縮強さで規定される品質基準を満たすために固化材の量を増やす方法が採用されることもある。
The expected performance of such backfill materials includes the compressive strength in the depth direction and the ability to transmit the overload evenly to the surrounding ground without compressing the volume even when a lateral load is generated during an earthquake. is there.
Conventionally, only the result of the uniaxial compression test was used to confirm whether the fluidized soil satisfies the above-described performance. However, although the fluidized soil is distributed in the depth direction, a constant value is applied to the uniaxial compressive strength used as the quality reference value. Currently, the standard of uniaxial compressive strength used is 200 kPa or more.
In addition, in the conventional fluidized soil, in order to improve filling properties and workability, there are many fluidized soils with low density in which the amount of construction generated soil is reduced. Even in a fluidized soil with a low density, the uniaxial compressive strength can be secured if there is a certain consolidation force due to cementation of the solidified material. For this reason, a method of increasing the amount of solidified material may be employed for fluidized soil with low density in order to satisfy the quality standard defined by the uniaxial compressive strength.
そこで本発明の発明者らによって、周辺地盤からの拘束圧の下で周辺地盤と同等のせん断抵抗力を発揮させるために、三軸圧縮試験の結果を利用して流動化処理土の密度を決定する方法が提案された（特許文献１参照）。 Therefore, the inventors of the present invention determine the density of the fluidized soil using the results of the triaxial compression test in order to exert the same shear resistance as the surrounding ground under the restraining pressure from the surrounding ground. Has been proposed (see Patent Document 1).
前記した従来の流動化処理土の品質基準決定方法にあっては、次のような問題点がある。
＜１＞コンクリートを打設して構造物を構築する場合とは異なり、流動化処理土の強度は硬ければ良いというものではない。埋戻した箇所を再掘削して新たに別の構造物を構築したり、改修したりすることも多いため、ハンドシャベル等による再掘削が容易におこなえる程度の強度に留めるのが望ましい。その一方で、埋戻した流動化処理土が大幅に圧縮して地表面が沈下したり、地震時の横荷重によって破壊して構造物との間に空隙を発生させたりする事態は避けなければならない。しかし、従来において適切な品質基準値がなかったため、過剰設計となり易く、不経済であった。また、強度を高めすぎた結果、再掘削が困難になる場合もあった。
＜２＞三軸圧縮試験の結果を品質管理に適用するのは望ましい方法ではあるが、試験に手間と時間を要するため、品質管理の頻度に影響が出る場合もある。
The above-described conventional quality standard determination method for fluidized soil has the following problems.
<1> Unlike the case of constructing a structure by placing concrete, the strength of the fluidized soil is not necessarily hard. In many cases, the backfilled portion is re-excavated to newly construct another structure or repair, and therefore it is desirable that the strength should be such that re-excavation with a hand shovel or the like can be easily performed. On the other hand, it is necessary to avoid situations in which the fluidized soil that has been backfilled compresses significantly and the ground surface sinks, or breaks due to a lateral load during an earthquake and creates a void between the structure. Don't be. However, since there was no appropriate quality standard value in the past, it was easy to overdesign and it was uneconomical. Moreover, as a result of increasing the strength too much, re-digging may become difficult.
<2> Although it is desirable to apply the results of the triaxial compression test to quality control, since the test requires time and effort, the frequency of quality control may be affected.
上記のような課題を解決するために、本発明の流動化処理土の品質基準決定方法は、被処理土と、固化材と、比重を調整した調整泥水又は水とを混練して製造する流動化処理土の品質基準決定方法において、前記流動化処理土の配置される位置の平均有効拘束圧の１．１倍と、前記流動化処理土の配置される位置の地山強度と、前記流動化処理土の配置される位置の鉛直応力と水平応力の偏差応力と、を比較し、最も大きな値を基準にして前記流動化処理土の品質基準となる一軸圧縮強さを決定する方法である。ここで、前記平均有効拘束圧には、例えば有効土被り圧と有効水平土圧を基に平均化して算定した前記流動化処理土が配置される位置の想定拘束圧が該当する。また、前記偏差応力は、鉛直応力を地山の有効土被り圧とし、水平応力を地山の静止土圧から受動土圧までの範囲の任意の値による有効水平土圧として算定した前記流動化処理土が配置される位置の最大地山せん断強度とすることができる。 In order to solve the problems as described above, the quality standard determination method for fluidized soil according to the present invention is a fluid produced by kneading the soil to be treated, the solidified material, and the adjusted mud or water adjusted in specific gravity. In the method for determining the quality standard of the fluidized soil, 1.1 times the average effective restraint pressure at the position where the fluidized soil is disposed, the ground strength at the position where the fluidized soil is disposed, and the flow This is a method for comparing the vertical stress at the position where the liquefied soil is arranged with the deviation stress of the horizontal stress, and determining the uniaxial compressive strength that is the quality standard of the fluidized soil based on the largest value. . Here, the average effective confining pressure corresponds to an assumed confining pressure at a position where the fluidized soil, which is calculated by averaging based on the effective soil covering pressure and the effective horizontal earth pressure, is arranged, for example. In addition, the deviation stress is the fluidization calculated by calculating the vertical stress as the effective earth cover pressure of the natural ground and the horizontal stress as the effective horizontal earth pressure by an arbitrary value in the range from the static earth pressure of the natural ground to the passive earth pressure. It can be set as the maximum natural shear strength at the position where the treated soil is arranged.
また、本発明の流動化処理土の品質基準決定方法は、被処理土と、固化材と、比重を調整した調整泥水又は水とを混練して製造する流動化処理土の品質基準決定方法において、前記流動化処理土の密度を少なくとも破壊時の体積収縮を低減できる密度とし、前記流動化処理土に荷重分散機能を所望する場合はさらに大きな密度基準値を適用することを特徴とした方法である。
The quality standard determination method for fluidized soil according to the present invention is a method for determining the quality standard of fluidized soil, which is produced by kneading the soil to be treated, the solidified material, and the adjusted mud water or water adjusted in specific gravity. The density of the fluidized soil is set to a density that can reduce at least the volume shrinkage at the time of breakage, and a larger density reference value is applied when a load distribution function is desired for the fluidized soil. is there.
本発明の流動化処理土の品質基準決定方法は、上記した課題を解決するための手段により、次のような効果の少なくとも一つを得ることができる。
＜１＞品質基準としては一軸圧縮強さのみによって管理する方が簡便であり、迅速かつ頻繁に品質管理をおこなうことができる。
＜２＞流動化処理土の密度を必要以上に大きくすることはないため、被処理土の混入量を削減できると共に、施工性を向上させることもできる。
＜３＞流動化処理土の強度を必要以上に大きくすることはないため、固化材混入量を削減できる。
The quality standard determination method for fluidized soil according to the present invention can obtain at least one of the following effects by means for solving the above-described problems.
<1> As a quality standard, it is easier to manage only by uniaxial compression strength, and quality management can be performed quickly and frequently.
<2> Since the density of the fluidized soil is not increased more than necessary, the amount of soil to be treated can be reduced and the workability can be improved.
<3> Since the strength of the fluidized soil is not increased more than necessary, the amount of mixed solid material can be reduced.
以下、本発明の実施の形態について説明する。 Embodiments of the present invention will be described below.
＜１＞流動化処理土
流動化処理土は、比重を調整した調整泥水又は水と、建設発生土などの被処理土を混練して製造する。
また、材料の分離抵抗性を確保するためにブリージング率を１％未満とするのが好ましい。ブリージング率は土木学会基準「プレパックトコンクリートの注入モルタルのブリージング率及び膨張試験法」（ＪＳＣＥ−１９８６）等により求めることができる。また、被処理土の種類及び流動化処理土に含まれる細粒土分と固化材の総和と水の割合、このような割合で製造された泥水の粘性などから推定することもできる。
さらに、充填性などの施工性を確保するために、流動性フロー値を１６０〜２５０ｍｍとするのが好ましい。
<1> Fluidized treated soil Fluidized treated soil is produced by kneading adjusted muddy water or water with adjusted specific gravity and treated soil such as construction generated soil.
Moreover, it is preferable that the breathing rate is less than 1% in order to ensure the separation resistance of the material. The breathing rate can be determined according to the Japan Society of Civil Engineers standard "Breathing rate and expansion test method of prepacked concrete injection mortar" (JSCE-1986). Moreover, it can also estimate from the kind of to-be-processed soil, the sum total of the fine grain content and solidification material which are contained in fluidization processing soil, the ratio of water, the viscosity of the mud produced at such a ratio, etc.
Furthermore, in order to ensure workability such as fillability, the fluidity flow value is preferably 160 to 250 mm.
＜２＞調整泥水
調整泥水は、細粒土を水に溶解して製造する泥水であって、泥水比重を１．１〜１．４に調整して製造する。
細粒土とは、建設現場などで発生した沖積粘土や関東ロームなどの、また現場で発生したスラリーや泥水などの、粘土分およびシルト分をいう。調整泥水は１種類又は複数の種類の細粒土を水に溶かして製造する。
流動化処理土を製造するに際しては、調整泥水と被処理土を混練する場合と、水と被処理土を混練する場合がある。調整泥水を製造するときに混合する細粒土に相当する土砂が被処理土に含まれていれば、直接、水と被処理土を混練することも可能である。しかし、流動化処理土の一軸圧縮強さは、土中の細粒分を主体とした泥水に添加された固化材の固化強さに支配され、粗粒土の強度への寄与は少ないため、一軸圧縮強さを制御して安定した品質の流動化処理土を製造するためには調整泥水を使用するのが好ましい。
<2> Adjusted muddy water Adjusted muddy water is muddy water produced by dissolving fine-grained soil in water, and is produced by adjusting the specific gravity of muddy water to 1.1 to 1.4.
Fine-grained soil refers to clay and silt such as alluvial clay and Kanto loam generated at construction sites, and slurry and muddy water generated at the site. Adjusted muddy water is produced by dissolving one or more types of fine-grained soil in water.
When the fluidized soil is produced, there are a case where the adjusted muddy water and the soil to be treated are kneaded and a case where the water and the soil to be treated are kneaded. If the soil to be treated contains earth and sand corresponding to the fine-grained soil to be mixed when producing the adjusted mud water, the water and the soil to be treated can be directly kneaded. However, the uniaxial compressive strength of fluidized soil is dominated by the solidification strength of the solidified material added to the mud containing mainly fine particles in the soil, and contributes little to the strength of the coarse-grained soil. In order to produce a fluidized soil with stable quality by controlling the uniaxial compressive strength, it is preferable to use conditioned muddy water.
＜３＞固化材
固化材の使用量は、セメント系の固化材の場合は流動化処理土１ｍ３に対して６０〜２００ｋｇ、石灰又は石膏系の固化材の場合は流動化処理土１ｍ３に対して１５０〜４００ｋｇとする。
密度の高い流動化処理土においては、添加していた固化材の量を従来に比べて減らし、施工上一時的に必要な程度の強度を確保するだけの量の固化材を添加するのが好ましい。この結果、流動化処理土の力学的性質を、土が本来もつ性質にすることができる。
<3> The amount of the solidifying material solidifying material, to the fluidized treated soil 1 m 3 in the case of solidifying material cementitious 60～200Kg, in the case of solidifying material of lime or gypsum to the fluidizing treated soil 1 m 3 On the other hand, it is 150 to 400 kg.
In high-density fluidized soil, it is preferable to add an amount of solidification material that is sufficient to temporarily secure the required strength for construction, by reducing the amount of solidification material that was added compared to the conventional method. . As a result, the mechanical properties of the fluidized soil can be made the properties inherent to the soil.
＜４＞被処理土
被処理土には、建設現場で発生する建設発生土や山砂などの砂質土を含有する土砂を使用する。
建設発生土のうち、砂などの良質な発生土は当然使用できるが、細粒分がやや多めの発生土や細粒分の多い粘性土などのそのまま再利用できない発生土も被処理土として有効に利用することができる。
<4> Soil to be treated As the soil to be treated, soil containing sandy soil such as construction generated soil or mountain sand generated at the construction site is used.
Of the generated soil, high-quality generated soil such as sand can be used as a matter of course, but generated soil that cannot be reused as it is, such as soil with slightly larger fine particles and viscous soil with more fine particles, is also effective as treated soil. Can be used.
＜５＞流動化処理土の一軸圧縮強さの基準
流動化処理土の強度に関する品質基準を、一軸圧縮強さのみによって確認できるように決定しておけば、頻繁に品質管理をおこなったとしても試験にかかる手間や費用はそれほど問題にならない。そこで本発明においては、一軸圧縮強さのみによって合理的に流動化処理土の強度に関する品質を確認できる流動化処理土の品質基準決定方法について提案する。
本発明では流動化処理土の一軸圧縮強さを決定する根拠となる各種強度を三つ設定する。一つは、圧縮強度であり、二つ目は地山強度（浅い地盤のせん断強度）であり、三つ目は深い地盤のせん断強度である。
<5> Criteria for uniaxial compressive strength of fluidized soil If quality standards for strength of fluidized soil are determined so that they can be confirmed only by uniaxial compressive strength, even if quality control is performed frequently The time and cost of the test are not a problem. Therefore, the present invention proposes a quality standard determination method for fluidized soil that can reasonably confirm the quality related to the strength of fluidized soil by only uniaxial compressive strength.
In the present invention, three kinds of various strengths that serve as a basis for determining the uniaxial compressive strength of the fluidized soil are set. One is compressive strength, the second is ground strength (shallow strength of shallow ground), and the third is shear strength of deep ground.
＜６＞流動化処理土の圧縮強度
圧縮強度の基準は、流動化処理土が圧密沈下しないために必要な圧縮強度を確保するという観点で設ける。
様々な目的でおこなわれた圧密非排水三軸試験の結果を整理した図を図１に示す。図１の縦軸には体積ひずみεv（％）を、横軸には初期圧密等方応力σ' cを一軸圧縮強さｑuで無次元化した値を示す。そして、流動化処理土の湿潤密度（g/cm3）と一軸圧縮強さ(kPa）毎に凡例を同じにして直線で繋いだ。
図１から湿潤密度と一軸圧縮強さの異なる圧縮曲線が、比較的狭い範囲に分布していることがわかる。すなわち、セメンテーション効果と密度効果による差異は圧縮にはあまり影響しないことがわかる。しかし、一軸圧縮強さの９０％程度以上の圧密等方応力が加わると、大幅に体積ひずみが増加することがわかる。特に、湿潤密度の小さな流動化処理土においては、圧密降伏後に圧縮指数が極端に大きくなる傾向が確認できた。
このため流動化処理土には、埋め戻された流動化処理土に加わる平均有効拘束圧の１１０％を上回る一軸圧縮強さが必要となる。ここで、平均有効拘束圧ｐは、有効土被り圧σｖ’、及び有効水平土圧σｈ’によって以下の式で算定できる。
<6> Compressive strength of fluidized soil The standard of compressive strength is provided from the viewpoint of securing the necessary compressive strength so that the fluidized soil does not settle down.
Fig. 1 shows a summary of the results of the compacted undrained triaxial test conducted for various purposes. The vertical axis of FIG. 1 represents the volumetric strain ε v (%), and the horizontal axis represents the value obtained by making the initial consolidated isotropic stress σ ′ c dimensionless with the uniaxial compressive strength qu. The legend was the same for each wet density (g / cm 3 ) and uniaxial compressive strength (kPa) of the fluidized soil, and they were connected in a straight line.
FIG. 1 shows that compression curves having different wet densities and uniaxial compressive strengths are distributed in a relatively narrow range. That is, it can be seen that the difference due to the cementation effect and the density effect does not significantly affect the compression. However, it can be seen that the volumetric strain increases significantly when a consolidation isotropic stress of about 90% or more of the uniaxial compressive strength is applied. In particular, in the fluidized soil with a low wet density, it was confirmed that the compression index tends to become extremely large after consolidation yielding.
For this reason, the fluidized soil requires a uniaxial compressive strength exceeding 110% of the average effective restraining pressure applied to the backfilled fluidized soil. Here, the average effective restraint pressure p can be calculated by the following formula using the effective earth pressure σ v ′ and the effective horizontal earth pressure σ h ′.
ｐ＝（σｖ’＋２σｈ’）／３ p = (σ v '+ 2σ h ') / 3
ここで有効水平土圧には、静止土圧から受働土圧までの範囲の任意の値を現場の状況や構造物の重要度等を考慮して採用することができる。
Here, as the effective horizontal earth pressure, any value in the range from static earth pressure to passive earth pressure can be adopted in consideration of the situation at the site and the importance of the structure.
＜７＞地山強度（浅い地盤のせん断強度）
埋め戻された流動化処理土は、地山のせん断強度以上でなければ性能に適わないため、地山強度を上回る一軸圧縮強さが必要となる。
地山強度は、粘性土であれば一軸圧縮試験が可能なので地山の圧縮試験を行い、流動化処理土はこの値を上回る一軸圧縮強さとする。地山が砂質土の場合は、一軸圧縮試験が不可能なため三軸圧縮試験を適用する。
地山のせん断強度は、埋戻し最深部に相当する有効土被り圧と受働土圧の最大せん断応力を採用するのが好ましい。流動化処理土には、この値を上回るせん断応力に相当する一軸圧縮強さが必要となる。
<7> Ground strength (shear strength of shallow ground)
Since the fluidized soil that has been backfilled is not suitable for performance unless it is equal to or higher than the shear strength of the natural ground, uniaxial compressive strength that exceeds the natural ground strength is required.
The natural ground strength can be a uniaxial compression test if it is a cohesive soil, so the natural ground compression test is performed, and the fluidized soil has a uniaxial compressive strength exceeding this value. When the natural ground is sandy soil, the triaxial compression test is applied because the uniaxial compression test is impossible.
As the shear strength of the natural ground, it is preferable to employ the effective shear pressure corresponding to the deepest backfill portion and the maximum shear stress of the passive earth pressure. The fluidized soil requires a uniaxial compressive strength corresponding to a shear stress exceeding this value.
＜８＞深い地盤のせん断強度
深い場所に堆積する粘性土は大きな有効土被り圧による圧密が進行しているため地山の一軸圧縮強さは大きい。流動化処理土には、この値を上回る一軸圧縮強さが求められる。
砂質土は、有効拘束圧により最大せん断応力が異なるが、特に深い埋戻し部では有効拘束圧が大きくなり最大せん断応力も大きくなる。この場合の最大せん断応力は地山の有効土被り圧と、静止土圧から受働土圧までの範囲の任意の値による有効水平土圧との偏差応力となる。ここで、構造物の深い部分の有効水平土圧は、多くの設計指針が静止土圧を採用している。
<8> Shear strength of deep ground Cohesive soil that accumulates in deep places has large uniaxial compressive strength because of consolidation due to large effective soil pressure. The fluidized soil is required to have a uniaxial compressive strength exceeding this value.
Sandy soils have different maximum shear stresses depending on the effective confining pressure, but the effective confining pressure increases and the maximum shear stress also increases, especially in deep backfill areas. The maximum shear stress in this case is the deviation stress between the effective earth pressure of the natural ground and the effective horizontal earth pressure with an arbitrary value in the range from static earth pressure to passive earth pressure. Here, as for the effective horizontal earth pressure in the deep part of the structure, many design guidelines adopt static earth pressure.
＜９＞流動化処理土の密度の基準
流動化処理土の品質基準に密度（湿潤密度）の基準を採用する意義は、埋戻しや裏込めした流動化処理土に構造物から荷重が集中して加わる場合、地震によって大きな荷重が加わる場合、あるいはセメンテーション効果が低下する場合などに、荷重を分散する効果、構造物の変形を抑制する効果、長期の耐久性を確保する効果を求めるためである。従来の流動化処理土の湿潤密度の基準は、高密度とする場合は1.5 g/cm3以上とし、低密度の場合でも1.35 g/cm3以上としている。
<9> Criteria for density of fluidized soil The significance of using density (wet density) as the quality standard for fluidized soil is that loads from structures are concentrated on backfilled or backfilled fluidized soil. In order to obtain the effect of dispersing the load, the effect of suppressing deformation of the structure, and the effect of ensuring long-term durability when a large load is applied by an earthquake, or when the cementation effect decreases. is there. The standard of wet density of the conventional fluidized soil is 1.5 g / cm 3 or more for high density and 1.35 g / cm 3 or more for low density.
＜１０＞荷重分散効果を期待する場合の密度
そこで、荷重分散の観点から湿潤密度を考えると、有効拘束圧300 kPaの深い部分の埋戻しとなる間隙比1.86（湿潤密度1.6 g/cm3)の流動化処理土は、若干の正のダイレイタンシーを示し、応力ひずみ曲線においてもじん性を示した。この間隙比を境にダイレイタンシーとじん性の発現に違いが見られるので、湿潤密度1.5 g/cm3以上の基準に替わり湿潤密度1.6 g/cm3以上とすれば安全側の基準になる。確実に荷重分散効果を期待する場合は、湿潤密度1.8 g/cm3程度の湿潤密度を基準とするのが適切である。
また、有効土被り圧によって荷重分散効果を期待する場合の密度を分類すると、有効土被り圧50 kPa以下となる浅い埋戻しに流動化処理土を使用する場合は湿潤密度1.6 g/cm3以上、有効土被り圧50〜100 kPaとなる比較的深い埋戻しに流動化処理土を使用する場合は湿潤密度1.7 g/cm3以上、有効土被り圧100 kPa以上となる深い埋戻しに流動化処理土を使用する場合は砂の相対密度0.8以上に相当する湿潤密度とする基準が適切である。
<10> Density when expecting load dispersion effect Therefore, considering the wet density from the viewpoint of load dispersion, a gap ratio of 1.86 (wet density of 1.6 g / cm 3 ) is used to backfill the deep portion of the effective confining pressure of 300 kPa. This fluidized soil showed some positive dilatancy and was also tough in the stress-strain curve. There is a difference in the expression of dilatancy and toughness at the boundary of this gap ratio, so if the wet density is 1.6 g / cm 3 or more instead of the wet density of 1.5 g / cm 3 or more, it becomes a safety standard . In order to ensure the load dispersion effect, it is appropriate to use a wet density of about 1.8 g / cm 3 as a reference.
Also, when the density when the load dispersion effect is expected by the effective soil cover pressure is classified, the wet density is 1.6 g / cm 3 or more when fluidized soil is used for shallow backfilling where the effective soil cover pressure is 50 kPa or less. When fluidized soil is used for relatively deep backfilling with an effective soil cover pressure of 50 to 100 kPa, fluidization is performed for deep backfilling with a wet density of 1.7 g / cm 3 or higher and an effective soil cover pressure of 100 kPa or higher. When treated soil is used, a standard for a wet density corresponding to a sand relative density of 0.8 or more is appropriate.
＜１１＞体積圧縮低減効果を期待する場合の密度
体積変化の観点から湿潤密度を考えると、有効拘束圧が100 kPa以上の深い部分の埋戻しとなる流動化処理土は、すべて体積が収縮する傾向を示し、有効拘束圧が100 kPa以下では体積収縮が小さくなる傾向を示した。
一方、流動化処理土の密度増には限界があり、高い有効拘束圧下での体積収縮を抑えることは難しい。流動化処理土が完全に破壊すると、地山が破壊しない場合でも体積収縮が発生し、構造物は変形する。この場合は一軸圧縮強さだけが品質基準となり、上記の「深い地盤のせん断強度」の段落で説明した有効土被り圧と有効水平土圧の偏差応力を上回る一軸圧縮強さが合理的と考えられる。
これに対して、有効応力50〜100 kPaでは間隙比1.86以下（湿潤密度1.6 g/cm3以上）であれば体積変化が少ない傾向がある。また、有効拘束圧20〜50 kPaでは、間隙比5.19以下（湿潤密度1.29 g/cm3以上）でも体積変収縮は小さい傾向が示された。
そこで、構造物の重要性を考慮して体積圧縮を極力低減する場合、浅い有効土被り圧50 kPa以下となる埋戻しに流動化処理土を使用する場合は湿潤密度1.35 g/cm3以上、有効土被り圧50〜100 kPaとなる比較的深い埋戻しに流動化処理土を使用する場合は湿潤密度1.6 g/cm3以上、有効土被り圧100 kPa以上となる深い埋戻しに流動化処理土を使用する場合は砂の相対密度0.7以上に相当する湿潤密度とする基準が適切である。
<11> Density when expecting volume reduction effect Considering the wet density from the viewpoint of volume change, the volume of all fluidized soils that will be used for backfilling deep parts with an effective confining pressure of 100 kPa or more will shrink. There was a tendency, and the volumetric shrinkage tended to decrease when the effective confining pressure was 100 kPa or less.
On the other hand, there is a limit to increasing the density of fluidized soil, and it is difficult to suppress volume shrinkage under high effective restraint pressure. When the fluidized soil is completely destroyed, even if the ground is not destroyed, volume shrinkage occurs and the structure is deformed. In this case, only the uniaxial compressive strength becomes the quality standard, and the uniaxial compressive strength exceeding the deviation stress between the effective earth cover pressure and the effective horizontal earth pressure described in the paragraph of “Deep ground shear strength” above is considered reasonable. It is done.
On the other hand, if the effective stress is 50 to 100 kPa, the volume change tends to be small if the gap ratio is 1.86 or less (wet density 1.6 g / cm 3 or more). Further, when the effective restraint pressure was 20 to 50 kPa, the volumetric shrinkage tended to be small even at a gap ratio of 5.19 or less (wet density of 1.29 g / cm 3 or more).
Therefore, considering the importance of the structure, when reducing volume compression as much as possible, when using fluidized soil for backfilling where the shallow effective earth covering pressure is 50 kPa or less, a wet density of 1.35 g / cm 3 or more, When fluidized soil is used for relatively deep backfilling with an effective soil pressure of 50 to 100 kPa, fluidization is performed for deep backfilling with a wet density of 1.6 g / cm 3 or higher and an effective soil pressure of 100 kPa or higher. When soil is used, a standard for a wet density corresponding to a relative density of sand of 0.7 or more is appropriate.
実施例１では、本発明の流動化処理土の一軸圧縮強さの決定手順を適用した計算例について説明する。 In Example 1, a calculation example to which the uniaxial compressive strength determination procedure of the fluidized soil of the present invention is applied will be described.
＜１＞深い埋戻しの場合１
埋戻し深さ20ｍ、地下水位GL−5.0ｍの薄い砂質土層がある沖積粘土地盤において本発明の流動化処理土の品質基準決定方法を適用した。ここで、地山の単位体積重量は15kN/m3、地盤の一軸圧縮強さは100 kPaである。
<1> 1 for deep backfilling
The quality standard determination method of fluidized soil of the present invention was applied to an alluvial clay ground with a thin sandy soil layer with a backfill depth of 20m and a groundwater level of GL-5.0m. Here, the unit volume weight of the natural ground is 15 kN / m 3 , and the uniaxial compressive strength of the ground is 100 kPa.
有効土被り圧 ：σｖ’＝１５×５＋５×１５＝１５０kPa
静止土圧 ：σｈ’＝０．４５×１５０＝６８kPa
平均有効拘束圧：（１５０＋２×６８）／３＝９５kPa
圧縮強度から決定される一軸圧縮強さ：ｑｕ＝９５×１．１＝１０４kPa以上
地山の一軸圧縮強さ：ｑｕ＝１００kPa以上
有効土被り圧 ：１５０kPa
静止土圧 ：６８kPa
砂質土が存在すると仮定した場合の一軸圧縮強さ
：ｑｕ＝（１５０−６８）＝８２kPa以上
一軸圧縮強さ ：ｑｕ＝１０４kPa以上（砂質土の存在を考慮して決定）
Effective earth covering pressure: σ v ′ = 15 × 5 + 5 × 15 = 150 kPa
Static earth pressure: σ h ′ = 0.45 × 150 = 68 kPa
Average effective restraint pressure: (150 + 2 × 68) / 3 = 95 kPa
Uniaxial compressive strength determined from compressive strength: qu = 95 × 1.1 = 104 kPa or more
Uniaxial compressive strength of natural ground: qu = 100kPa or more Effective earth covering pressure: 150kPa
Static earth pressure: 68kPa
Uniaxial compressive strength assuming that sandy soil exists
: Qu = (150-68) = 82 kPa or more
Uniaxial compressive strength: qu = 104kPa or more (determined considering the presence of sandy soil)
＜２＞深い埋戻しの場合２
埋戻し深さ20ｍ、地下水位GL−10.0ｍの洪積粘性土地盤において本発明の流動化処理土の品質基準決定方法を適用した。ここで、地山の単位体積重量は15kN/m3、地盤の一軸圧縮強さは400kPaである。
<2> In case of deep backfill 2
The method for determining the quality standard of the fluidized soil of the present invention was applied to a clayey ground with a backfill depth of 20m and a groundwater level of GL-10.0m. Here, the unit volume weight of the natural ground is 15 kN / m 3 , and the uniaxial compressive strength of the ground is 400 kPa.
有効土被り圧 ：σｖ’＝１５×１０＋５×１０＝２００kPa
静止土圧 ：σｈ’＝０．４５×２００＝９０kPa
平均有効拘束圧：（２００＋２×９０）／３＝１２７kPa
圧縮強度から決定される一軸圧縮強さ強度
：ｑｕ＝１２７×１．１＝１４０kPa以上
地山の一軸圧縮強さ：ｑｕ＝４００kPa以上
有効土被り圧 ：２００kPa
静止土圧 ：９０kPa
深い地盤のせん断強度から決定される一軸圧縮強さ
：ｑｕ＝（２００−９０）＝１１０kPa以上
一軸圧縮強さ ：４００kPa以上（地山強度により決定）
Effective earth covering pressure: σ v ′ = 15 × 10 + 5 × 10 = 200 kPa
Static earth pressure: σ h ′ = 0.45 × 200 = 90 kPa
Average effective restraint pressure: (200 + 2 × 90) / 3 = 127 kPa
Uniaxial compressive strength determined from compressive strength
: Qu = 127 × 1.1 = 140 kPa or more
Uniaxial compressive strength of natural ground: qu = 400kPa or more Effective earth covering pressure: 200kPa
Static earth pressure: 90kPa
Uniaxial compressive strength determined from the shear strength of deep ground
: Qu = (200−90) = 110 kPa or more
Uniaxial compressive strength: 400kPa or more (determined by natural ground strength)
＜３＞深い埋戻しの場合３
埋戻し深さ20ｍ、地下水位GL−10.0ｍの砂質土地盤において本発明の流動化処理土の品質基準決定方法を適用した。ここで、地山の単位体積重量は19kN/m3、静止土圧係数0.4である。
<3> 3 for deep backfilling
The method for determining the quality standard of fluidized soil of the present invention was applied to sandy ground with a backfill depth of 20m and a groundwater level of GL-10.0m. Here, the unit volume weight of the natural ground is 19 kN / m 3 and the static earth pressure coefficient is 0.4.
有効土被り圧 ：σｖ’＝１９×１０＋９×１０＝２８０kPa
静止土圧 ：σｈ’＝０．４×２８０＝１１２kPa
平均有効拘束圧：（２８０＋２×１１２）／３＝１６８kPa
圧縮強度から決定される一軸圧縮強さ強度
：ｑｕ＝１６８×１．１＝１８５kPa以上
地山の一軸圧縮強さ相当：適用外
有効土被り圧 ：２８０kPa
受働土圧 ：σａ’＝２．０×２８０＝５６０kPa
深い地盤のせん断強度から決定される一軸圧縮強さ：
ｑｕ＝（５６０−２８０）＝２８０kPa以上
一軸圧縮強さ ：２８０kPa以上（深さ強度により決定）
Effective earth covering pressure: σ v ′ = 19 × 10 + 9 × 10 = 280 kPa
Static earth pressure: σ h ′ = 0.4 × 280 = 112 kPa
Average effective restraint pressure: (280 + 2 × 112) / 3 = 168 kPa
Uniaxial compressive strength determined from compressive strength
: Qu = 168 × 1.1 = 185 kPa or more
Equivalent compressive strength of natural ground: Effective soil cover pressure not applicable : 280kPa
Passive earth pressure: σ a ′ = 2.0 × 280 = 560 kPa
Uniaxial compressive strength determined from the shear strength of deep ground:
cu = (560-280) = 280 kPa or more
Uniaxial compressive strength: 280kPa or more (determined by depth strength)
＜４＞浅い埋戻しの場合
埋戻し深さ4ｍ、地下水位GL−2.0ｍの関東ローム粘土地盤において本発明の流動化処理土の品質基準決定方法を適用した。ここで、地山の単位体積重量は15kN/m3、地盤の一軸圧縮強さは300kPaである。
<4> In the case of shallow backfilling The quality standard determination method for fluidized soil of the present invention was applied to Kanto Loam clay ground with a backfill depth of 4 m and a groundwater level of GL-2.0 m. Here, the unit volume weight of the natural ground is 15 kN / m 3 , and the uniaxial compressive strength of the ground is 300 kPa.
有効土被り圧 ：σｖ’＝１５×２＋５×２＝４０kPa
静止土圧 ：σｈ’＝０．５×４０＝２０kPa
平均有効拘束圧：（４０＋２×２０）／３＝２７kPa
圧縮強度から決定される一軸圧縮強さ
：ｑｕ＝２７×１．１＝３０kPa以上
地山の一軸圧縮強さ：ｑｕ＝３００kPa以上
有効土被り圧 ：４０kPa
受働土圧 ：σａ’＝３．０×４０＝１２０kPa
浅い地盤のせん断強度から決定される一軸圧縮強さ
：ｑｕ＝（１２０−４０）＝８０kPa
一軸圧縮強さ ：ｑｕ＝３００kPa以上（地山強度優先）
Effective earth covering pressure: σ v ′ = 15 × 2 + 5 × 2 = 40 kPa
Static earth pressure: σ h ′ = 0.5 × 40 = 20 kPa
Average effective restraint pressure: (40 + 2 × 20) / 3 = 27 kPa
Uniaxial compressive strength determined from compressive strength
: Qu = 27 × 1.1 = 30 kPa or more
Uniaxial compressive strength of natural ground: qu = 300kPa or more Effective earth covering pressure: 40kPa
Passive earth pressure: σ a ′ = 3.0 × 40 = 120 kPa
Uniaxial compressive strength determined from the shear strength of shallow ground
: Qu = (120-40) = 80 kPa
Uniaxial compressive strength: qu = 300kPa or more (ground strength priority)
実施例２では、本発明の流動化処理土の密度の決定手順を適用した計算例について説明する。 In Example 2, a calculation example to which the determination procedure of the density of the fluidized soil according to the present invention is applied will be described.
＜１＞杭の水平抵抗確保する場合
埋戻し深さ4ｍ、地下水位GL−2.0ｍの関東ローム粘土地盤において本発明の流動化処理土の品質基準決定方法を適用した。ここで、地山の単位体積重量は15kN/m3、地盤の一軸圧縮強さは300kPaである。
<1> When securing horizontal resistance of piles The quality standard determination method for fluidized soil of the present invention was applied to Kanto Loam clay ground with a backfill depth of 4 m and a groundwater level of GL-2.0 m. Here, the unit volume weight of the natural ground is 15 kN / m 3 , and the uniaxial compressive strength of the ground is 300 kPa.
有効土被り圧 ：σｖ’＝１５×２＋５×２＝４０kPa
受動土圧 ：σｈ’＝１．０×４０＝４０kPa
平均有効拘束圧：（４０＋２×４０）／３＝４０kPa
荷重分散効果を期待する場合の密度：ρt＝１．６g／m ３ 以上
破壊時の体積圧縮低減のみを期待する場合の密度：ρ ｔ ＝１．４ｇ／ｍ ３ 以上
Effective earth covering pressure: σ v ′ = 15 × 2 + 5 × 2 = 40 kPa
Passive earth pressure: σ h '= 1.0 × 40 = 40 kPa
Average effective restraint pressure: (40 + 2 × 40) / 3 = 40 kPa
Density when the load dispersion effect is expected: ρt = 1.6 g / m 3 or more
Density when only volume compression reduction at the time of destruction is expected: ρ t = 1.4 g / m 3 or more
＜２＞共同溝の地震時の変形を抑制する場合
埋戻し深さ10ｍ、地下水位GL−5.0ｍの沖積粘土地盤において本発明の流動化処理土の品質基準決定方法を適用した。ここで、地山の単位体積重量は15kN/m3、地盤の一軸圧縮強さは100kPaである。
<2> In the case of suppressing deformation at the time of an earthquake in the joint ditch The quality standard determination method for fluidized soil of the present invention was applied to an alluvial clay ground with a backfill depth of 10 m and a groundwater level of GL-5.0 m. Here, the unit volume weight of the natural ground is 15 kN / m 3 , and the uniaxial compressive strength of the ground is 100 kPa.
有効土被り圧 ：σｖ’＝１５×５＋５×５＝１００kPa
受動土圧 ：σｈ’＝１．０×１００＝１００kPa
平均有効拘束圧：（１００＋２×１００）／３＝１００kPa
荷重分散効果を期待する場合の密度：ρt＝１．７ｇ／m ３ 以上
破壊時の体積圧縮低減のみを期待する場合の密度：ρ ｔ ＝１．６ｇ／ｍ ３ 以上
Effective earth covering pressure: σ v ′ = 15 × 5 + 5 × 5 = 100 kPa
Passive earth pressure: σ h '= 1.0 × 100 = 100 kPa
Average effective restraint pressure: (100 + 2 × 100) / 3 = 100 kPa
Density when load distribution effect is expected: ρt = 1.7 g / m 3 or more
Density when only volume compression reduction at the time of destruction is expected: ρ t = 1.6 g / m 3 or more
従って、流動化処理土が破壊しても充填効果は残り、構造物の大きな変形を抑制する場合は、流動化処理土の湿潤密度はρt＝１．６g／m３以上となり、構造物の変形を極力抑制する場合は流動化処理土の湿潤密度はρt＝１．７g／m３以上となる。
Therefore, even if the fluidized soil breaks down, the filling effect remains, and when the large deformation of the structure is suppressed, the wet density of the fluidized soil becomes ρt = 1.6 g / m 3 or more, and the deformation of the structure In order to suppress as much as possible, the wet density of the fluidized soil becomes ρt = 1.7 g / m 3 or more.
Claims (4)
前記流動化処理土の配置される位置の平均有効拘束圧の１．１倍と、
前記流動化処理土の配置される位置の地山強度と、
前記流動化処理土の配置される位置の鉛直応力と水平応力の偏差応力と、を比較し、
最も大きな値を基準にして前記流動化処理土の品質基準となる一軸圧縮強さを決定する、
流動化処理土の品質基準決定方法。
In the quality standard determination method of the fluidized treated soil produced by kneading the treated soil, the solidified material, and the adjusted mud or water adjusted in specific gravity,
1.1 times the average effective restraint pressure at the position where the fluidized soil is disposed;
The natural ground strength at the position where the fluidized soil is disposed,
Compare the vertical stress of the position where the fluidized soil is arranged and the deviation stress of the horizontal stress,
Determine the uniaxial compressive strength that is the quality standard of the fluidized soil based on the largest value,
Quality standard determination method for fluidized soil.
前記平均有効拘束圧は、有効土被り圧と有効水平土圧を基に平均化して算定した前記流動化処理土が配置される位置の想定拘束圧であることを特徴とする、
流動化処理土の品質基準決定方法。
In the quality standard determination method of the fluidized soil according to claim 1,
The average effective restraint pressure is an assumed restraint pressure at a position where the fluidized soil is calculated by averaging based on an effective earth cover pressure and an effective horizontal earth pressure,
Quality standard determination method for fluidized soil.
前記偏差応力は、鉛直応力を地山の有効土被り圧とし、水平応力を地山の静止土圧から受動土圧までの範囲の任意の値による有効水平土圧として算定した前記流動化処理土が配置される位置の最大地山せん断強度であることを特徴とする、
流動化処理土の品質基準決定方法。
In the quality standard determination method of the fluidized soil according to claim 1 or 2,
The deviation stress is the fluidized soil that has been calculated as an effective horizontal earth pressure with an arbitrary value in the range from the static earth pressure to the passive earth pressure of the natural ground, with the vertical stress being the effective earth pressure of the natural ground and the horizontal stress. It is the maximum natural shear strength at the position where
Quality standard determination method for fluidized soil.
前記流動化処理土の密度を少なくとも破壊時の体積収縮を低減できる密度とし、
前記流動化処理土に荷重分散機能を所望する場合はさらに大きな密度基準値を適用することを特徴とした、
流動化処理土の品質基準決定方法。 In the quality standard determination method of the fluidized treated soil produced by kneading the treated soil, the solidified material, and the adjusted mud or water adjusted in specific gravity,
The density of the fluidized soil is at least a density that can reduce volume shrinkage at the time of destruction,
When a load distribution function is desired for the fluidized soil, a larger density reference value is applied,
Quality standard determination method for fluidized soil.
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| JP2008031638A (en) * | 2006-07-26 | 2008-02-14 | Kajima Corp | Underground filler and repair method for earth structure |
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| JP2008031638A (en) * | 2006-07-26 | 2008-02-14 | Kajima Corp | Underground filler and repair method for earth structure |
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