WO2022176977A1

WO2022176977A1 - Site improvement method

Info

Publication number: WO2022176977A1
Application number: PCT/JP2022/006644
Authority: WO
Inventors: 浩司長澤
Original assignee: 花王株式会社
Priority date: 2021-02-22
Filing date: 2022-02-18
Publication date: 2022-08-25
Also published as: JPWO2022176977A1; JP7265691B2

Abstract

A site improvement method that excavates soil having a density of 0.4 g/cm³ to 2.5 g/cm³ (inclusive) using a slurry containing water (W) and a powder (P), wherein the powder (P) contains (A) an inorganic powder (referred to hereinafter as component (A)) having a BET specific surface area of 1.2 m²/g to 5 m²/g (inclusive), the proportion of component (A) in the powder (P) is 10 mass% or more, and the mass ratio (W)/(P) of the water (W) and powder (P) contained in the slurry is 70-150 mass% (inclusive).

Description

Soil improvement method

The present invention relates to a ground improvement method, a leakage prevention material for drilling slurry, drilling slurry, use of drilling slurry for drilling soil, and a method for producing drilling slurry.

BACKGROUND ART As a method for improving the foundation for constructing a building, there is a method for improving the ground by driving a concrete or steel pipe soil improvement column into the ground, and a method for injecting a cement-based solidification material such as cement milk while excavating the ground. A soil improvement method is known in which a column-shaped soil improvement body formed by mixing excavated soil and a cement-based solidifying material such as cement milk is directly formed in the ground.
In addition, as one of the methods for improving the foundation, the ground is excavated to create a vertical hole, a reinforced cage is inserted into the hole, and concrete is injected to form a concrete pile in the ground. The piling method is known.
One of the foundation pile construction methods for building foundation piles is the pre-boring foot protection method. After excavating the soil with an auger to a predetermined depth (bearing layer) while injecting drilling fluid, foot protection fluid is injected into the tip of the excavation. is erected in this excavation hole, fixed in the foot protection liquid by press-fitting or tapping, and the pile and the ground are integrated by hardening the foot protection liquid and the pile circumference fixing liquid.

Japanese Patent Application Laid-Open No. 2018-193515 discloses that a humus soil solidification material for improving organic soft ground contains cement, blast furnace slag, and anhydrous gypsum, and that the Blaine specific surface area of this ground granulated blast furnace slag is 8000 cm ² / is greater than or equal to g.

Outline of the Invention When the ground improvement method involves excavating the soil, when the slurry supplied to the soil (for example, solidifying material such as cement milk, drilling fluid, etc.) flows into the surrounding ground during soil excavation, more of slurry is required, which is not preferable in terms of economy and excavation work efficiency. In addition, from the viewpoint of allowing the slurry to function effectively, it is not preferable for the slurry to flow out to the surrounding ground of the excavated portion. The technology disclosed in JP-A-2018-193515 cannot be said to be sufficient for suppressing the outflow of slurry to the surrounding ground of the excavation section.

The present invention provides a ground improvement method for suppressing the outflow of slurry supplied to the soil during soil excavation or the like to the surrounding ground of the excavated part, a leakage prevention material for excavated slurry, an excavated slurry, and an excavated slurry for soil excavation. and a method for producing a drilling slurry.

The present invention is a ground improvement method for excavating soil having a density of 0.4 g / cm ³ or more and 2.5 g / cm ³ or less using a slurry containing water (W) and powder (P). The powder (P) contains (A) an inorganic powder having a BET specific surface area of 1.2 m ² /g or more and 5 m ² /g or less [hereinafter referred to as component (A)], , The ratio of component (A) is 10% by mass or more, and the mass ratio (W)/(P) of water (W) and powder (P) in the slurry is 70% by mass or more and 150% by mass or less. , relating to ground improvement methods.

In addition, the present invention uses water (W) and powder (P) as powder (P) in a drilling slurry containing water (W) and powder (P) at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less, A liquid leakage prevention material for excavation slurry that prevents the excavation slurry from flowing out to the ground around the excavation part, comprising the component (A), wherein the component (A) is 10% with respect to the powder (P) The present invention relates to a leakage prevention material for drilling slurry, which is used at a rate of mass % or more.

In addition, the present invention contains water (W) and powder (P) at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less, and the powder (P) is the component (A) It relates to a drilling slurry containing 10% by mass or more.

The present invention also relates to the use of the above excavation slurry for excavating soil having a density of 0.4 g/cm ³ or more and 2.5 g/cm ³ or less.

Further, in the present invention, water (W) and powder (P) are blended at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less, and the powder (P) is The present invention relates to a method for producing a drilling slurry, in which component (A) is blended in a proportion of 10% by mass or more with respect to (P).

INDUSTRIAL APPLICABILITY According to the present invention, a ground improvement method for suppressing the outflow of slurry supplied to the soil during soil excavation to the surrounding ground of an excavation section, a liquid leakage prevention material for excavation slurry, an excavation slurry, and an excavation slurry for soil excavation and methods for producing drilling slurries.

FIG. 1 shows the mixing ratio of the component (A) in the powder (P) in Examples 3-1a to 3-1h, and the ratio of the slurry passage rate to the slurry passage rate (reference value) of Comparative Example 3-1a. is a graph showing the relationship between

Mode for carrying out the invention In the soil improvement method of the present invention, the mechanism by which the outflow of the slurry supplied to the soil is suppressed is not clear, but the powder (P) contained in the slurry is (A) BET ratio It contains an inorganic powder having a surface area of 1.2 m ² /g or more and 5 m ² /g or less [hereinafter referred to as component (A)], and the ratio of component (A) in powder (P) is 10% by mass or more. Therefore, it is considered that this inorganic powder immediately blocks the gaps in the soil physically and suppresses the leakage of the slurry. In particular, the inventors found that when the amount of powder (P) is small relative to water, the mobility of particles in the slurry is high, so the component (A) moves quickly and can efficiently block the gaps in the soil. Therefore, it was found that the effect of suppressing leakage of slurry by the component (A) is enhanced. Even when the powder (P) is less than the water, if the amount of the powder (P) is out of the predetermined range, the effect of suppressing leakage of the slurry is improved even if the component (A) is used. I found out not to. On the other hand, the inventors found that when there is a large amount of powder (P) relative to water, the viscosity of the slurry is generally high and the mobility of the particles inside is low, so the component (A) can efficiently fill the gaps in the soil. It was found that the liquid leakage suppressing effect of the component (A) was difficult to manifest. That is, for soil with many voids filled with air or moisture, the inorganic powder (A) with a specific specific surface area in the powder (P) blocks the gaps in the soil, and the water (W) and the powder ( When the mass ratio ((W)/(P)) of P) is within a specific range, the inorganic powder (A) can efficiently reach the crevices of the soil. As a result, it is presumed that the outflow of the slurry to the surrounding ground of the excavated portion is suppressed. The present invention was completed based on these findings, and when a slurry having a predetermined mass ratio (W)/(P) of water (W) and powder (P) is used, the hardening of the slurry Since the leakage of the slurry is suppressed without waiting for , it is possible to perform smooth construction during excavation.
The ground improvement method, leakage prevention material for drilling slurry, and drilling slurry of the present invention are effective in suppressing the outflow of slurry with a relatively large amount of water, and by suppressing the outflow of the slurry, the slurry can function effectively. can.

<Soil Improvement Method>
The ground improvement method of the present invention excavates soil having a density of 0.4 g / cm ³ or more and 2.5 g / cm ³ or less using a slurry containing water (W) and powder (P). In the ground improvement method, the powder (P) contains the (A) component, the proportion of the (A) component in the powder (P) is 10% by mass or more, and the water (W) of the slurry The mass ratio (W)/(P) of the powder (P) is 70% by mass or more and 150% by mass or less. Examples of the slurry used in the soil improvement method of the present invention include a slurry obtained by blending the leakage prevention material for excavation slurry of the present invention and water, which will be described in detail later. In the present invention, when the mass ratio is represented by "% by mass", it means the ratio of the numerator when the denominator is 100.

Water (W) includes water used in the field of ground improvement, such as fresh water and seawater. Water (W) includes, for example, groundwater, tap water, river water, lake water, and seawater.

As for powder (P), an inorganic powder is mentioned. Powder (P) exists as a solid in the slurry. The powder (P) includes inorganic powders generally used in civil engineering, such as inorganic powders (1) to (4) enumerated for component (A), which will be described later in detail. The powder (P) is an inorganic powder having a solubility of 5 or less in 100 cm ³ of water at 20°C. The solubility is the maximum mass (g) of powder (P) that can be dissolved in 100 cm ³ of water at 20°C. The solubility of component (A) and the solubility of component (B), which will be described later, are also determined by the same method as for the powder (P).

The powder (P) contains the (A) component. The powder (P) contains the component (A) as a slurry leakage prevention material. The inorganic powder as the component (A) is not particularly limited, but one or more inorganic powders selected from the following inorganic powders (1) to (4) can be used.
(1) Hydraulic powders such as cement and gypsum (2) Pozzolanic powders such as fly ash, silica fume, volcanic ash, woody biomass combustion ash, and silicate clay (3) Coal ash, blast furnace slag, diatoms Latent hydraulic powder such as soil (4) Silicate such as kaolin, aluminum silicate, clay, talc, mica, calcium silicate, sericite, and bentonite

Component (A) is one or more inorganic powders selected from the above (1) to (4) from the viewpoint of being safe for addition to soil and being industrially stably available. (3) one or more inorganic powders selected from latent hydraulic powders such as coal ash, blast furnace slag, and diatomaceous earth are more preferred, and blast furnace slag is even more preferred. Blast furnace slag includes water granulated blast furnace slag, slow-cooled blast furnace slag, and the like.

Component (A) has a BET specific surface area of 1.2 m ² /g or more, preferably 1.5 m ² /g or more, more preferably 1.7 m ² , from the viewpoint of efficiently closing voids in the ground. /g or more, and from the viewpoint of suppressing the outflow of slurry, it is 5 m ² /g or less, preferably 4.5 m ² /g or less, more preferably 4 m ² /g or less, further preferably 2 m ² /g or less , and more preferably 1.8 m ² /g or less. The BET specific surface area is calculated by a method based on the BET flow method (single-point method/multi-point method) and "JISZ8830:2013 Method for measuring specific surface area of powder (solid) by gas adsorption". Specifically, the BET specific surface area is calculated by a fully automatic specific surface area measuring device "Macsorb" manufactured by MOUNTECH Co., LTD. From the viewpoint of suppressing the outflow of the slurry into the ground by physically blocking the gaps in the ground, the component (A) is the time from slurry kneading until the slurry is injected into the ground (for example, up to about 1 hour ), and those in which the BET specific surface area does not change significantly are preferable.

The solubility of component (A) in water at 20°C is preferably 5 or less, more preferably 3 or less, and still more preferably 1 or less, from the viewpoint of efficiently blocking soil pores.

The average particle size of component (A) is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more, from the viewpoint of efficient filling of voids in the soil without the slurry penetrating into the soil. And, from the viewpoint of densely filling the voids of the soil with a large number of particles, the particle size is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less. The average particle size of component (A) is a value calculated using a HORIBA LA-920 laser diffraction/scattering particle size distribution analyzer. In addition, the measurement solvent is ethanol.

As the component (A), for example, a powder with a normal particle size distribution and a coefficient of variation of 50 or less can be used.

The component (A) is preferably non-porous powder. The term "non-porous powder" as used herein means a powder having a smooth particle surface and having no fine structure such as pores. For example, cement obtained by pulverizing clinker, ground granulated blast furnace slag obtained by pulverizing blast furnace slag, etc., are commercialized by pulverizing raw materials with large particle sizes of several centimeters or more industrially. thing applies.

Powder (P) is, in addition to component (A), optionally (B) an inorganic powder having a BET specific surface area of 0.4 m ² /g or more and 1.0 m ² /g or less [hereinafter referred to as component (B)]. can include

The inorganic powder as the component (B) is not particularly limited, and one or more inorganic powders selected from the inorganic powders (1) to (4) listed for the component (A) above are used. be able to.

Component (B) is safe to be added to soil and is industrially stably available, so that (1) hydraulic powder such as cement and gypsum, (2) fly ash, Pozzolanic powders such as silica fume, volcanic ash, woody biomass combustion ash, silicate clay, etc. (3) Latent hydraulic powders such as coal ash, blast furnace slag, diatomaceous earth, etc. (4) Kaolin, aluminum silicate , clay, talc, mica, calcium silicate, sericite, bentonite and other silicates are preferred. Component (B) is preferably, for example, cement or gypsum, and more preferably cement, from the viewpoint of general availability. Cement includes ordinary portland cement, blast furnace cement, belite cement, moderate heat cement, high-early-strength cement, super-early-strength cement, sulfate-resistant cement, and the like.

Component (B) has a BET specific surface area of 0.4 m ² /g or more, preferably 0.5 m ² /g or more, more preferably 0.5 m 2 /g or more, from the viewpoint of ensuring powder mixability with component (A). 0.6 m ² /g or more, and from the viewpoint of efficiently blocking relatively large voids in the soil, it is 1.0 m ² /g or less, preferably 0.9 m ² /g or less, more preferably 0.9 m 2 /g or less. 8 m ² /g or less. The BET specific surface area is calculated by a method based on the BET flow method (single-point method/multi-point method) and "JISZ8830:2013 Method for measuring specific surface area of powder (solid) by gas adsorption". Specifically, the BET specific surface area is calculated by a fully automatic specific surface area measuring device "Macsorb" manufactured by MOUNTECH Co., LTD.

The solubility of component (B) in water at 20°C is preferably 5 or less, more preferably 3 or less, and still more preferably 1 or less, from the viewpoint of efficiently closing the pores of the soil.

As component (B), for example, a powder with a normal distribution of particle sizes and a coefficient of variation of 50 or less can be used.

The component (B) is preferably non-porous powder. The term "non-porous powder" as used herein means a powder having a smooth particle surface and having no fine structure such as pores.

The slurry contains water (W) and powder (P). In the slurry, the mass ratio (W)/(P) of water (W) to the powder (P) is from the viewpoint of ensuring pumpability during construction and increasing the mobility of the powder (A) in the slurry. Therefore, it is 70% by mass or more, preferably 75% by mass or more, more preferably 80% by mass or more, and from an economic point of view such as construction time and material costs associated with slurry injection, a smaller amount of slurry preparation is lost. Since liquid prevention is required, the content is 150% by mass or less, preferably 140% by mass or less, more preferably 130% by mass or less, and even more preferably 110% by mass or less. The mass ratio (W)/(P) of water (W) and powder (P) in this slurry is [[content (mass) of water (W) in slurry]/[powder (P ) content (mass)]]×100. Also, this mass ratio (W)/(P) can be calculated based on the blending amounts of water (W) and powder (P).

The proportion of component (A) in the powder (P) is 10% by mass or more, preferably 25% by mass or more, more preferably 30% by mass or more, from the viewpoint of efficiently closing fine voids in the soil. , More preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 55% by mass or more, and from the viewpoint of wide application to various soils, 100% by mass or less, preferably 80% by mass 70% by mass or less, more preferably 70% by mass or less. As the powder (P), for example, the ratio of the component (A) in the powder (P) is 100% by mass, that is, the powder composed of the component (A) can be used. In the present invention, the amount of component (A), component (B), etc. can be regarded as the respective content in the powder (P) or slurry (the same applies hereinafter).

In addition, the powder (P) contains the (A) component and optionally the (B) component, and the total ratio of the (A) component and the (B) component in the powder (P) is the fine voids in the soil. From the viewpoint of efficient blocking, preferably 70% by mass or more, more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 90% by mass or more, and various From the viewpoint of wide application to various soils, the content is 100% by mass or less, preferably 99% by mass or less, more preferably 98% by mass or less, and still more preferably 95% by mass or less. As the powder (P), for example, the total ratio of the components (A) and (B) in the powder (P) is 100% by mass, that is, powder composed of the components (A) and (B) is used. be able to.

When the slurry contains the component (B), the mass ratio (B)/(A) of the content of the component (A) and the content of the component (B) is from the viewpoint of efficiently closing various voids in the soil. Therefore, it is preferably 0.4 or more, more preferably 0.6 or more, still more preferably 1 or more, and preferably 2.3 or less from the viewpoint of efficiently closing both large and fine voids in the soil. , more preferably 2 or less, and still more preferably 1.5 or less.

From the viewpoint of ensuring the effect of preventing leakage of liquid, the slurry preferably has a content of component (A) in the slurry of 6% by mass or more, more preferably 12% by mass or more, and still more preferably 17% by mass or more, and It is preferably 55% by mass or less, more preferably 50% by mass or less, and even more preferably 44% by mass or less.

When the slurry contains the (A) component and the (B) component, the total content of the (A) component and the (B) component in the slurry is preferably 6 mass from the viewpoint of ensuring the effect of preventing liquid loss. % or more, more preferably 12 mass % or more, still more preferably 17 mass % or more, and preferably 55 mass % or less, more preferably 50 mass % or less, still more preferably 44 mass % or less.

The slurry preferably has a funnel viscosity (500 ml/500 ml) of 180 seconds or less, more preferably 150 seconds or less, and even more preferably 120 seconds or less, from the viewpoint of ensuring the pumpability of the slurry during construction and avoiding clogging by the slurry. is. Here, the funnel viscosity is the viscosity measured using a Marsh funnel viscometer, which measures the viscosity based on the outflow time (seconds) required for discharging 500 ml of slurry placed in a 500 ml funnel-shaped container. The funnel viscosity can be measured by, for example, the outflow time of the total amount of slurry (500 mL) using a Marsh funnel viscometer (funnel) viscometer (model: KS-192, manufacturer: Kansai Kiki Seisakusho, capacity: 500 mL). Funnel viscosity is, for example, a value measured at 20°C. In addition, from the viewpoint of ensuring the pumpability of the slurry during construction, it is preferable that the outflow time of the slurry is as short as possible.

The slurry can also contain other ingredients. Examples thereof include AE agents, retarders, foaming agents, thickeners, foaming agents, waterproofing agents, fluidizing agents, dispersing agents and the like. The slurry may contain components that dissolve in water.

Examples of the slurry include excavating slurry supplied to the soil during ground excavation. milk, etc.).

Examples of ground improvement methods of the present invention include ground improvement methods involving soil excavation using slurry.

The ground improvement method of the present invention is a construction method for excavating soil using slurry, such as a middle layer mixing treatment method, a deep layer mixing treatment method, a power blender method, a prefabricated pile embedding method, and a cast-in-place pile method. It can be preferably applied. In the ground improvement method of the present invention, from the viewpoint of suppressing the outflow of slurry to the surrounding ground of the excavated part, the method selected from the middle layer mixing method, the deep layer mixing method, the power blender method and the existing pile embedding method. It can be used preferably.

For example, in the case of the intermediate layer mixed treatment method, it is possible to prevent leakage of slurry having excavation lubrication and hardening action, and directly form a column-shaped soil improvement body in the ground.
In addition, for example, in the case of the method of embedding ready-made piles, the leakage of slurry during soil excavation is prevented, and the leakage of foot protection liquid and pile circumference fixing liquid is prevented, and foundation piles can be formed in the ground.

Since the ground improvement method of the present invention suppresses the outflow of the slurry supplied to the soil from the excavated part to the surrounding soil during soil excavation, it is possible to use the soil with many voids filled with air or moisture. Suitable. The density of the soil to be excavated is 0.4 g/cm ³ or more from the viewpoint of the soil being hard enough for a construction machine to enter, and the gaps are such that the outflow of the slurry becomes more pronounced. is 2.5 g/cm ³ or less from the viewpoint that the soil contains The density of the soil is 0.4 g/cm ³ or more, preferably 0.5 g/cm ³ or more, more preferably 0.6 g/cm ³ or more, still more preferably 1.5 g/cm ³ or more, and 2.5 g /cm ³ or less, preferably 2.3 g/cm ³ or less, more preferably 2.0 g/cm ³ or less. The density of soil is measured according to JIS A 1225 "Wet soil density test method". According to the ground improvement method of the present invention, specifically, it is possible to effectively excavate soil that has many structural gaps such as gravel and peat soil that contains a large amount of organic matter and water and from which slurry easily flows out. can be suppressed from flowing out of the liquid component from the excavated portion to the surrounding soil.

<Drain prevention material for drilling slurry>
The present invention uses water (W) and powder (P) as powder (P) in an excavating slurry containing water (W) and powder (P) at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less. A liquid leakage prevention material for excavation slurry that prevents slurry from flowing out to the ground around an excavation part, comprising component (A), wherein component (A) is 10% by mass with respect to powder (P) Provided is a leakage prevention material for drilling slurry (hereinafter referred to as a leakage prevention material) that is used at the above ratio.
The leakage prevention material of the present invention may optionally contain component (B). Examples of the anti-leakage material of the present invention include an anti-leakage material containing the component (A) or an anti-leakage material containing the components (A) and (B). In the present invention, the blending amounts of the components (A) and (B) when preparing the leakage prevention material can be regarded as the respective contents in the powder (P) and the drilling slurry (hereinafter referred to as similar).

Specific examples and preferred embodiments of the components (A), (B) and powder (P) in the leakage prevention material of the present invention are the same as those described in the ground improvement method of the present invention. The usage ratio of component (A) to (P), the preferred mass ratio (W)/(P) of water (W) and powder (P) in the excavation slurry, etc. are described in the slurry of the ground improvement method of the present invention. is the same as The soil to which the excavation slurry containing the leakage prevention material of the present invention is applied is effective for the soil described in the ground improvement method of the present invention, but the density of the target soil and the target ground are It is not limited to the above.

In the leakage prevention material of the present invention, the content of component (A) is preferably 30% by mass or more, more preferably 40% by mass or more, and still more preferably from the viewpoint of efficiently closing fine voids in the soil. 50% by mass or more, and from the viewpoint of wide application to various soils, it is preferably 100% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. As the anti-leakage material of the present invention, for example, the content of the component (A) is 100% by mass, that is, the anti-leakage material consisting of the (A) component can be used.

Further, the leakage prevention material of the present invention contains (A) component and optionally (B) component, and the total content of (A) component and (B) component in the leakage prevention material is From the viewpoint of efficiently blocking such voids, it is preferably 70% by mass or more, more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, and still more preferably 90% by mass or more. From the viewpoint of wide application to various soils, the content is 100% by mass or less, preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less. As the anti-leakage material of the present invention, for example, the total content of the components (A) and (B) is 100% by mass, that is, the anti-leakage material composed of the (A) component and the (B) component can be used. can.

When the leakage prevention material of the present invention contains the component (B), the mass ratio (B)/(A) of the content of the component (A) to the content of the component (B) is determined by various voids in the soil. From the viewpoint of efficiently blocking, it is preferably 0.4 or more, more preferably 0.6 or more, and still more preferably 1 or more, and from the viewpoint of efficiently blocking both large and fine voids in the soil, It is preferably 2.3 or less, more preferably 2 or less, and still more preferably 1.5 or less.

The liquid leakage prevention material of the present invention includes conventional cement dispersants, water-soluble polymer compounds, air entraining agents, cement wetting agents, swelling agents, waterproofing agents, retardants, quick setting agents, thickeners, flocculating agents, drying Components such as shrinkage reducing agents, strength enhancers, curing accelerators and preservatives [excluding those corresponding to components (A) and (B)] may be included.

The anti-leakage material of the present invention may be in either a liquid state in which the anti-leakage material is mixed with water or the like, or in a solid state such as powder, and is more preferably powder.

<Drilling slurry>
The present invention contains water (W) and powder (P) at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less, and the powder (P) contains 10 % by mass or more.
The drilling slurry of the present invention may optionally contain component (B). As the drilling slurry of the present invention, for example, a drilling slurry containing the leakage prevention material for drilling slurry of the present invention can be used.

Specific examples and preferred embodiments of the (A) component, (B) component and powder (P) in the drilling slurry of the present invention are the same as those described in the ground improvement method of the present invention, and the preferred water of the drilling slurry The mass ratio (W)/(P) and viscosity of (W) and powder (P) are the same as those described for the slurry of the ground improvement method of the present invention.

The excavating slurry of the present invention is useful in any field such as soil improvement, pile foundation construction, and tunnel construction. The excavation slurry of the present invention can be suitably used for construction methods such as intermediate layer mixing processing method, deep layer mixing processing method, power blender method, ready-made pile embedding method, and cast-in-place pile method. From the viewpoint of injecting the paste, the excavation slurry of the present invention is more preferably used in a construction method selected from an intermediate layer mixing method, a deep layer mixing method, a power blender method, and a prefabricated pile embedding method.
In addition, the excavation slurry of the present invention is used for excavating soil having a density of 0.4 g/cm ³ or more and 2.5 g/cm ³ or less from the viewpoint of suppressing the outflow of the slurry to the surrounding ground of the excavation part. preferably.
That is, the present invention provides use of the excavating slurry of the present invention for excavating soil having a density of 0.4 g/cm ³ or more and 2.5 g/cm ³ or less.

[Method for producing drilling slurry]
In the present invention, water (W) and powder (P) are blended at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less, and the powder (P) is Provided is a method for producing a drilling slurry in which the component (A) is blended at a rate of 10% by mass or more with respect to ).
A method for producing a drilling slurry of the present invention includes a method for producing a drilling slurry in which the component (A), the powder (P) other than the component (A), and water are mixed. As a method for producing the drilling slurry of the present invention, there is a method for producing a drilling slurry in which the leakage prevention material for drilling slurry of the present invention and water are blended.

Specific examples and preferred embodiments of the (A) component, (B) component, powder (P), etc. used in the method for producing the excavating slurry of the present invention are the same as those described in the ground improvement method of the present invention, The preferred mass ratio (W)/(P) of water (W) and powder (P) and the viscosity of the excavating slurry are the same as those described for the slurry of the ground improvement method of the present invention. The preferred content mentioned in the slurry of the ground improvement method of the present invention is the preferred compounding amount of the method for producing the drilling slurry of the present invention. Furthermore, as a method for producing the drilling slurry of the present invention, for example, the (A) component, an optional (B) component, and powder (P) other than the (A) component and the (B) component are mixed to obtain ( Examples include a method for producing a drilling slurry for producing a drilling slurry containing component A) and optional component (B).

In the method for producing the drilling slurry of the present invention, the water (W) and the powder (P) are mixed by any method as long as the performance of the components (A), (B) and the drilling slurry is not deteriorated. can be done.

Examples Components used in Examples or Comparative Examples are shown below.
- (A) component (A1) ground blast furnace slag (Nippon Steel Cement Co., Ltd. Spirits 8000): BET specific surface area 1.78 m ² /g
(A2) Ground blast furnace slag (Nippon Steel Cement Co., Ltd. Spirits 6000): BET specific surface area 1.25 m ² /g

The BET specific surface area can be obtained directly by the BET flow method (single-point method/multi-point method) and a method based on "JISZ8830:2013 Method for measuring the specific surface area of powder (solid) by gas adsorption". It can be obtained indirectly from the relationship between the specific surface area and the BET specific surface area. As an example, for ground granulated blast furnace slag, the following linear approximation formula was derived based on the measured values of Blaine specific surface area and BET specific surface area of components (A1), (A2), and (B2) below. , the BET specific surface area can be obtained from the Blaine specific surface area by this linear approximation.
・ Spirits 4000: Blaine specific surface area = 4000 cm ² /g, BET specific surface area = 0.94 m ² /g
・ Spirits 6000: Blaine specific surface area = 6000 cm ² /g, BET specific surface area = 1.25 m ² /g
・ Spirits 8000: Blaine specific surface area = 8000 cm ² /g, BET specific surface area = 1.78 m ² /g
Blaine specific surface area (cm ² /g) = 4593.8 x BET specific surface area (m ² /g) - 94.4

・(B) Component (B1) Ordinary Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.): BET specific surface area 0.72 m ² /g
(B2) Ground blast furnace slag (Nippon Steel Cement Co., Ltd. Spirits 4000): BET specific surface area 0.94 m ² /g

<BET specific surface area>
The BET specific surface areas of components (A) and (B) are based on the BET flow method (single-point method/multi-point method) and "JISZ8830:2013 Method for measuring the specific surface area of powder (solid) by gas adsorption". calculated by the method. Specifically, the BET specific surface area of each component was calculated using a fully automatic specific surface area measuring device "Macsorb" manufactured by MOUNTECH Co., LTD.

<Examples and Comparative Examples>
Drilling slurries having the compositions shown in Tables 1 to 3 were prepared, and the leakage prevention effect of the leakage prevention material for drilling slurry was evaluated based on the following slurry passage rate (%) and slurry passage rate (%). gone. In Tables 2 and 3, the compounding ratio corresponds to the ratio (% by mass) of component (A) or component (B) in powder (P).

[Method for preparing drilling slurry]
Component (A1), component (A2), and component (B1) are added to water so that the mixing ratio shown in Tables 1 to 3 and the mass ratio (W)/(P) of water (W) and powder (P) are obtained. Alternatively, the component (B2) was blended and kneaded for 1 minute using a commercially available hand mixer to obtain a drilling slurry.

[Slurry passage rate]
First, a glass filter G1 (JIS pore size: 100 to 120 μm) and a cock were attached to a glass column having an inner diameter of 25 mm and a height of 400 mm. This column was packed with 100 g of No. 3 silica sand. The density of silica sand was 2.0 g/cm ³ when measured according to JIS A 1225 "Wet Density Test Method for Soil".
Next, 100 g of drilling slurry prepared with the composition shown in Tables 1 to 3 was added to the column with the cock of the column closed, and the cock was opened after the addition. The measurement was started when the cock was opened, and the mass (g) of the drilling slurry that flowed out from the cock was measured for 10 minutes from the measurement start time. Then, the ratio (% by mass) of the mass (g) of the drilling slurry flowing out of the cock in 10 minutes to the mass (g) of the drilling slurry added to the column is calculated, and this ratio is referred to as the slurry passage rate (%). did. The results are shown in Tables 1-3. The lower the slurry passage rate, the higher the leakage prevention effect of the excavation slurry by the leakage prevention material. The slurry of each example has a mass ratio (W)/(P) of water (W) and powder (P) that is suitable for drilling slurry (for example, funnel viscosity (500 ml/500 ml) is 180 seconds below), it has a high liquid leakage prevention effect, and the powder (P) used is also a component used as an excavating slurry, so it does not impair its function as an excavating slurry when excavating soil. can be used for

Further, in a drilling slurry having the same mass ratio (W)/(P) of water (W) and powder (P), the slurry passage rate of the drilling slurry that does not contain the (A) component is set as a reference value, and The rate (%) of the excavation slurry passage rate was calculated respectively. Tables 2 and 3 show the ratio (%) of the slurry passage rate. Further, when the slurry passage rate of Comparative Example 3-1a in Table 3 is taken as a reference value, the blending ratio of the component (A) in the powder (P) and Examples 3-1a to 3- for this reference value FIG. 1 shows the relationship with the rate of slurry passing rate for 1 h.

From the results of the ratio (%) of the slurry passage rate in Tables 2 and 3, the leakage prevention material of the present invention has the same mass ratio (W) / (P) of water (W) and powder (P) However, it can be seen that the leakage of the liquid is effectively prevented by the influence of the component (A). For example, as shown in FIG. 1, in a drilling slurry in which the mass ratio (W)/(P) of water (W) and powder (P) is 100, when the compounding ratio of component (A) is 0 (comparative example 3-1a, reference value), when the compounding ratio of component (A) was 10% by mass (Example 3-1h), the ratio of the slurry passage rate to the reference value was significantly reduced. Therefore, by using the excavation slurries of Examples 3-1a to 3-1h, it is considered that the outflow of the excavation slurry to the ground surrounding the excavation can be suppressed, and smooth construction can be performed during excavation.

Claims

A soil improvement method for excavating soil having a density of 0.4 g/cm 3 or more and 2.5 g/cm 3 or less using a slurry containing water (W) and powder (P),
The powder (P) contains (A) an inorganic powder having a BET specific surface area of 1.2 m 2 /g or more and 5 m 2 /g or less [hereinafter referred to as component (A)],
The proportion of the component (A) in the powder (P) is 10% by mass or more,
The mass ratio (W)/(P) of water (W) and powder (P) in the slurry is 70% by mass or more and 150% by mass or less.
Soil improvement method.
The ground according to claim 1, wherein the powder (P) contains (B) an inorganic powder having a BET specific surface area of 0.4 m 2 /g or more and 1.0 m 2 /g or less [hereinafter referred to as component (B)]. How to improve.
The ground improvement method according to claim 2, wherein the component (B) is cement.
The ground improvement method according to claim 2 or 3, wherein the total content of the components (A) and (B) in the powder (P) is 70% by mass or more.
Claims 2 to 4, wherein the mass ratio (B)/(A) of the content of the component (A) to the content of the component (B) in the powder (P) is 0.4 or more and 2.3 or less. The ground improvement method according to any one of the items.
The ground improvement method according to any one of claims 2 to 5, wherein the total content of component (A) and component (B) in the slurry is 12% by mass or more and 55% by mass or less.
The ground improvement method according to any one of claims 1 to 6, wherein the ground improvement method is an intermediate layer mixing method or a deep layer mixing method.
The ground improvement method according to any one of claims 1 to 7, wherein the proportion of component (A) in the powder (P) is 30% by mass or more.
The ground improvement method according to any one of claims 1 to 8, wherein the component (A) is blast furnace slag.
The soil improvement method according to any one of claims 1 to 9, wherein the content of component (A) in the slurry is 6% by mass or more and 55% by mass or less.
The ground improvement method according to any one of claims 1 to 10, which is a method selected from the middle layer mixing method, the deep layer mixing method, the power blender method, and the prefabricated pile embedding method.
The powder (P) is used in an excavating slurry containing water (W) and powder (P) at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less, and the excavating slurry is used as the excavating portion A leakage prevention material for drilling slurry that prevents outflow to the ground around the
(A) contains an inorganic powder having a BET specific surface area of 1.2 m 2 /g or more and 5 m 2 /g or less [hereinafter referred to as component (A)],
(A) component is used in a proportion of 10% by mass or more with respect to the powder (P),
Liquid leakage prevention material for drilling slurry.
Containing water (W) and powder (P) at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less,
The powder (P) contains 10% by mass or more of (A) an inorganic powder having a BET specific surface area of 1.2 m 2 /g or more and 5 m 2 /g or less.
drilling slurry.
Use of the excavating slurry according to claim 13 for excavating soil having a density of 0.4 g/cm 3 or more and 2.5 g/cm 3 or less.
Water (W) and powder (P) are blended at a mass ratio (W)/(P) of 70% by mass or more and 150% by mass or less,
As the powder (P), (A) an inorganic powder having a BET specific surface area of 1.2 m 2 /g or more and 5 m 2 /g or less is blended at a rate of 10% by mass or more with respect to the powder (P).
A method for producing a drilling slurry.