JPH08199160A - Excavation additive - Google Patents

Abstract

PURPOSE: To produce an excavation additive for mud-pressure shield-tunneling method, composed of a viscous slurry composition obtained by adding a specific polymer to a clay suspension, capable of easily producing a liquid having high concentration, specific gravity and viscosity, converting excavated sand and earth to a plastic fluid and enabling the excavation of even a ground having high gravel content without causing the problems of blocking, powder generation, etc. CONSTITUTION: This excavation additive is composed of a viscous slurry composition produced by adding (A) 0.05-1.0wt.% of a water-soluble polymer partly insoluble in water [e.g. a reverse-phase W/O-type emulsion produced by copolymerizing water-soluble vinyl monomers such as a mixture of 20-40mol% of a (meth)acrylic acid salt and acrylamide and 1-100ppm (especially 5-30ppm) (based on the total amount of the water-soluble vinyl monomers) of a crosslinkable monomer by a radical generation agent, ultraviolet rays, radiations, etc.] to (B) a suspension of clay (e.g. mountain clay having a methylene blue adsorption of <=50meq/100g).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavating additive for excavating particularly soily soil with a mud pressure shield method. More specifically, the present invention relates to a drilling additive that provides high specific gravity and high viscosity without using bentonite.

[0002]

2. Description of the Related Art There is a shield construction method as a method of constructing a tunnel such as a subway or a construction of a sewer pipe, and various construction methods are used. In recent years, an earth pressure type shield construction method is relatively used.

The earth pressure type shield construction method is a kind of mechanical closed type shield as shown in Article 13 of the same commentary of the Japan Society of Civil Engineers Tunnel Standard Specification (Shield Edition).

In the excavation / earth retaining of the earth pressure type shield construction method, the chamber is filled with the earth and sand excavated by the cutter head, and the earth pressure in the chamber causes the face to be excavated while stabilizing the cutting face, and the inside of the chamber is passed into the shield machine. It is carried out by discharging soil with a screw conveyor.

At the time of construction, the earth pressure in the chamber is kept by the shield propulsion force to the extent necessary to stabilize the face, while the screw conveyor rotation speed and propulsion speed are adjusted so that the soil can be discharged in proportion to the propulsion amount. Is a method of adjusting.

When the ground is cohesive soil, the content of fine particles is large and the soil is easily deformed or destroyed, and therefore the excavated soil is often in a mud state with plastic fluidity. However, sand or gravel, especially gravel. In the case of the ground where the ratio of the number is large and the content of fine particles is small, the solidification phenomenon and arching occur in the shield machine chamber and the screw conveyor, and the sediment does not move continuously, and it is impossible to excavate and it is impossible to proceed. There is.

As described above, since the fluidity and water stopping property of the excavated soil may be insufficient depending on the soil quality, the excavated additive material such as mud soil material and sludge is injected into the excavated soil to make the excavated soil have water stopping ability and fluidity. There is a method of converting the soil into sand and stabilizing the face by the earth pressure of the converted soil. This type is the construction method called mud pressure shield or sludge shield.

In order to change the properties of the excavated earth and sand, the excavated additive is injected by an additive injection device to fill the voids in the chamber, and the excavated additive is forcibly converted into excavated earth by a mixing blade device or the like. It is necessary to mix and convert the excavated sediment into sediment having plastic flowability and impermeability.

There are various types of excavating additives for that purpose. In each case, the mud pressure shield method can excavate a wider range of geological ground by changing the combination of materials and the concentration injection amount. Become.

Conventional drilling additives are made of water-soluble polymers such as mountain clay, bentonite and carboxymethyl cellulose, and are named mud materials, mud materials and mud materials.

These are intended to make up a mud by supplementing the lack of fine particles in the ground by injecting an additive material, and in the case of the ground such as sand or gravel having a large hydraulic conductivity, a large amount of particles will be present between the particles. The purpose is to improve water-stopping property and prevent jetting by filling the fine particles.

Further, by adhering viscous fine particles between soil particles having a large internal friction angle such as sand and gravel, the internal friction angle is reduced and the fluidity of excavated soil is increased. .

Therefore, for example, in the Mud Pressure Shield Method Association, the content of fine particles of 0.074 mm or less is 3
It is considered to be preferable to set the content to 0% or more, and in many cases, mud-making earth materials mixed and designed by the following calculation formula are used as excavating additives.

[0014]

[Equation 1] Concentration of mud soil material D = a (30-P0.074) α
+ (40-P0.25) β + (60-P2.0) γ

However, a is a coefficient based on a uniform coefficient a = 1.0 when the uniform coefficient U ≧ 4, a = 1.1 when 4> U ≧ 3,
When 3>U> 1, a = 1.2, P0.074 = 0.074
mm particle size passage percentage is 30% or more is 30, P0.25 =
0.25 mm particle size passage percentage of 40% or more is 40, P2.
0 = 2.0 mm Particle size passage percentage 60% or more is 60, α:
2.0, β: 0.5, γ: 0.5

However, according to the above equation, for example, the gravel rate is 70.
When calculating the case of about 100% gravel ground, the uniformity coefficient is 5
0, silt and clay content of 4.3%, P0.
074-4.3, P0.25 = 13.3, P2.0 = 2
4.2, the mud soil material concentration is about 72% (specific gravity 1.3
3 g / cc), and the amounts of bentonite and mountain clay used are calculated to be 156 kg and 391 kg per 1 m ^3, respectively.

When such a large amount of high-concentration bentonite mud is injected for excavation, a large amount of earth and sand must be treated as industrial waste, which often causes problems in securing a treatment site and treating costs.

[0018]

In the mud pressure type shield construction method, a drilling additive is added to non-mud excavating earth and sand, and the mixture is agitated by a mixing blade or the like at the rear part of the shield machine carter to improve plastic fluidity and impermeability. It is a method of converting it to mud and excavating it with a screw conveyor or an excavation pipe, but when excavating the ground with a large gravel rate such as boulder layer and cobblestone layer, it is a highly viscous and highly viscous addition It is necessary to inject a large amount of wood into the ground.

In this case, if the viscosity of the excavating additive material is insufficient, the binder effect for surrounding the soil particles is insufficient, and the earth and sand cause material separation, so that the fluidity cannot be improved.

The specific gravity of the excavating additive is important for suppressing sedimentation of soil particles, and needs to be adjusted according to the soil quality. In the case of rocks with a low content of silt and clay, it is necessary to increase the specific gravity of the drilling additive material as the gravel rate increases.

Bentonite has hitherto been used for adjusting the viscosity of clay suspensions composed mainly of mountain clay. As is well known, bentonite is one of the typical crystalline minerals containing montmorillonite as a main component, usually shares positive and negative charges, and has a very large specific surface area.

Therefore, it exhibits a thixotropic behavior in which the gel changes to a sol when it absorbs water at room temperature and swells up and a slight mechanical stimulus is applied. It is considered that such a unique viscosity of bentonite is effective for plasticizing the excavated soil, and the amount of bentonite used had to be increased as the gravel rate increased and the fine particle content decreased. .

However, since it is very difficult to physically and chemically separate bentonite from excavated soil mixed with bentonite generated after excavation, most of excavated sediment containing bentonite is treated as industrial waste. It was causing problems that had to be.

Further, the dissolution of bentonite requires a considerably long time for water swelling, which requires a long time for working the liquid and requires a facility for storing an amount that can be used for a considerably long time. Was also occurring.

As described above, bentonite often has a problem in treating residual soil, and bentonite has a water swelling property and can increase the viscosity of the suspension, but it gives a liquid specific gravity necessary for the slurry. Therefore, there has been a demand for a thickener having a thickening effect, which can form a clay suspension having a high concentration and a high specific gravity and a high viscosity without using bentonite as much as possible.

Water-soluble polymers used as polymer flocculants and the like are disclosed in JP-A-60-133084 and JP-A-3-1.
Japanese Patent No. 31400 discloses a method of using by utilizing a coagulation effect. However, a high molecular weight polyacrylamide water-soluble polymer used in a sludge dewatering method for domestic wastewater or industrial wastewater is dissolved in water. Then it becomes a long long chain, and when mixed with the clay suspension, the cohesive force is too strong to form flocs,
Clay content settles or agglomerates, the viscosity decreases significantly,
It cannot be redispersed even by mechanical stirring.

Further, when the cohesive force is too strong and mixed with the excavated soil, the sand and gravel, especially the gravel is separated from the mud, resulting in a non-uniform state in the shield machine chamber and the screw conveyor, and the continuous There is a problem that the soil cannot be removed and a closed state occurs.

Since the long-chain water-soluble polymer aggregates the clay particles in this way, the specific gravity of the clay suspension cannot be adjusted by the amount of clay, and a high-concentration, high-specific-gravity slurry additive is produced. It was not possible to use it for ground excavation with a small amount of silt and clay and a large amount of gravel and sand.

[0029]

[Means for Solving the Problem] When excavating uneven ground with a small amount of silt clay and a large amount of gravel and sand by the mud pressure shield construction method, it is necessary to use a high concentration to excavate the excavated soil by plasticizing it to promote stable excavation. Although it is necessary to inject a drilling additive with high specific gravity and high viscosity, a thickener having a large thickening power capable of adjusting the viscosity without using bentonite has been required.

As a result of intensive studies in view of these points, the present inventors have found that a water-soluble polymer which is partially insoluble in water is used in place of the high-molecular weight polyacrylamide-based water-soluble polymer to cause aggregation. The inventors have found that the drawbacks of sex can be solved all at once and reached the present invention.

That is, the present invention comprises a viscous sludge composition prepared by adding a water-soluble polymer partially insoluble in water to a suspension of clay, and is an excavation additive for a mud pressure type shield construction method. It concerns materials. The present invention will be described in detail below.

The water-insoluble polymer partially soluble in water used in the present invention is a polymer obtained by copolymerizing one or more water-based vinyl monomers and a crosslinkable monomer as a polymerization raw material, and a water-soluble polymer. It is neither water-soluble nor completely water-insoluble, and has a water swelling ratio of less than about 5 times.

The water-soluble vinyl monomer used in this polymer is (a) anionic and (b) nonionic, both of which are water-soluble. A specific example is as follows.

(A) Anionic monomer (meth) acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, itaconic acid, maleic acid, fumaric acid, arylsulfonic acid and salts thereof.

(B) Nonionic monomer (meth) acrylamide, vinyl methyl ether, vinyl ethyl ether and the like can be mentioned.

Specific examples of the crosslinkable monomer include
N'N-methylenebisacrylamide, N'N-methylenebismethacrylamide, divinyl compounds such as divinylbenzene, vinylmethyl methylol compounds such as methylolacrylamide and methylolmethacrylamide, vinyl aldehyde compounds such as acrolein,
Vinyl compounds such as methyl acrylamide glycolate methyl ether may be mentioned.

A polymer obtained by copolymerizing one or more of the water-soluble vinyl monomers described above and a crosslinkable monomer as a polymerization raw material with a radical generator, ultraviolet rays, radiation, etc. is effective in the present invention.

Alternatively, it is possible to polymerize the (meth) acrylamide alone and a crosslinkable monomer by copolymerization and then hydrolyze them to obtain the polymer of the present invention.

Polymerization forms of these polymers include aqueous solution polymerization, suspension polymerization, water-in-oil type reverse phase emulsion polymerization, and the like, and water-in-oil type reverse phase emulsion polymerization method is preferred. These manufacturing methods are, for example, Japanese Patent Publication No.
It can be performed by the known method introduced in Japanese Patent Publication No. 2-39417.

The amount of the crosslinkable monomer used is 1 pp with respect to the total amount of the water-soluble vinyl monomer in the presence of the chain transfer agent.
m to 100 ppm (weight ratio), preferably 5 ppm to
It is a copolymerized mixture of 30 ppm (weight ratio).

When the amount of the crosslinkable monomer is less than 1 ppm (weight ratio), a strong cohesive force equivalent to that of the water-soluble polymer is formed, flocs are formed, and clay is precipitated or agglomerated to significantly reduce the viscosity, resulting in mechanical It cannot be redispersed even by stirring.

Further, the cohesive force is too strong and when mixed with excavated soil, sand and gravel, especially gravel, are separated from mud. On the other hand, if it exceeds 100 ppm (weight ratio), it becomes a water-swellable polymer and the thickening effect is reduced, so that a clay suspension having an appropriate viscosity cannot be obtained.

The proportion of anionic monomer contained in the polymer is 20 to 40 mol%, preferably 25 to 40 mol%.
It is 35 mol%. If it exceeds this range, the cohesive force increases and the addition amount region exhibiting the thickening effect becomes narrow.

A preferred method for preparing this water-soluble polymer is
In the water-in-oil type reverse phase emulsion polymerization method, which has good solubility in a clay suspension, it is preferable that it is partially insoluble as a result of controlling the amount of the crosslinkable monomer.

The degree of crosslinking or chain branching can be controlled by polymerizing a crosslinkable monomer in the presence of a chain transfer agent to control the branching of the water-soluble polymer, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-198887. You can also do it.

When combined with a cross-linking agent, their use tends to promote branching over cross-linking and a moderate chain transfer agent must be used.

The degree of polymerization thereof is not clear because it has a partially crosslinked structure or a partially branched structure, but it can be considered as a polymer in which a general water-soluble polymer is slightly crosslinked or branched. The water swelling ratio of this polymer is preferably 5 times or less.

Instead of partially insolubilizing the polymer by crosslinking, it is also possible to use a polymer mixture containing sufficient water-insoluble polymer to partially insolubilize the water-soluble polymer.

The partially insoluble water-soluble polymer of the present invention is added to a clay suspension (usually in a concentration of 5 to 60% by weight of clay) in an amount of 0.05.
~ 1.0 wt% is added to make a slurry composition.

Clays used in the clay suspension of the present invention are generally clay minerals classified as miscellaneous clays whose mineral compositions vary widely. Bentonite, which is also called mountain clay, has a low montmorillonite content. Those that do not belong are preferred.

Further, it is preferable to use clay minerals for civil engineering, that is, as a water-stopping material such as an admixture of boring muddy water or grout and water leakage preventing soil.

Generally, clay minerals can be roughly classified into bentonite and other clays. The main use of bentonite is to disperse it in water to make low concentration mud, and to prevent the collapse of drilling holes and to transport excavated sediment.The required properties are mainly thickening and mud walls. It is plasticity.

Clays used in the present invention are mountain clays classified into clays other than bentonite, and those used as weighting materials in the shield construction method are preferable. The main use of mountain clay is as a basic material for adjusting specific gravity and viscosity, and it is also used for roof tile clay, cement clay, building material clay, and the like.

Many mountain clays are commercially available, but those having a low montmorillonite content are preferred. The amount of montmorillonite contained in the clay mineral is represented by methylene blue adsorption capacity (MBC, unit meq / 100 g).

The MBC value is a value indicating the amount of montmorillonite contained in mud water, and is titrated with a 1/100 normal methylene blue solution, and the amount of base exchange and the amount of montmorillonite contained, that is, the amount of bentonite contained is determined from the adsorbed amount of methylene blue by the following formula. The method is well known.

In this method, the exchangeable cations of montmorillonite exchange ions with the positively charged methylene blue molecules, so that the base exchange capacity (CE) of bentonite and mudstone is
This is a method of obtaining C) by the formula 1 and knowing the bentonite content from the formula 2.

[0057]

[Equation 2] Methylene blue exchange capacity (MBC) = methylene blue consumption (cc) / muddy water sample (cc) (Equation 1)

1 cc of the methylene blue solution to be titrated corresponds to 0.01 mg equivalent of methylene blue.

[0059]

## EQU3 ## Bentonite content (g / l) = 14.25 ×
Methylene blue consumption (Equation 2)

Bentonite refers to one having a high montmorillonite content and a high hydration and water swelling property. Bentonite for muddy water has a high Na salt type montmorillonite content and has a good swelling property and mud wall forming property. Bentonite is used.

Therefore, bentonite used for oil drilling mud or mud for civil engineering foundation construction is often bentonite from Nagata and Wyoming, USA, which has a high content of Na-salt-montmorillonite.

In order to use it in muddy water, it is necessary that the bentonite is of good quality and has a small amount of impurities and a high content of montmorillonite. For example, API (America)
The content of montmorillonite of "Kunigel VS" which conforms to the n Petroleum Institute standard is 75% or more.

Also, "Kunigel V1" which is a bentonite produced in Yamagata whose main component is Na-salt type montmorillonite, which is often used for drilling mud such as civil engineering stable liquid.
The MBC value of (Kunimine Industries Co., Ltd.) is 58 to 72.

On the other hand, the mountain clay used in the present invention has an MBC of 1
It is preferably about 50 meq / 100 g.

For example, commercially available mountain clays containing kaolinite and illite as main components include "Kibushi clay (SCP-S)" and "SCP-A" (both manufactured by Bentonite Sangyo Co., Ltd.). However, their MBCs are 13 and 9.4, respectively.

As an example of a mountain clay containing montmorillonite and kaolinite as a main component, which is commercially available, there is "Kasaoka clay" (manufactured by Kasanen Industry Co., Ltd.), but MBC is 2
It is as small as 3.8 and has low hydration and swelling properties.

Instead of using miscellaneous clays having a small montmorillonite content, it is also possible to substitute Ca salt for montmorillonite and use Ca salt type bentonite whose hydration and swelling properties are suppressed.

The superabsorbent resin may be added to the slurry composition of the present invention in an amount of 0.05 to 1.0% by weight.

The superabsorbent resin used absorbs water and swells from more than 5 times to nearly 1,000 times when brought into contact with water,
It is insoluble in water. Usually, most of the highly water-absorbent resin is powdery, but beads-like one having a particle size of 50 μm or more is preferable.

A method for producing these is described in, for example, Japanese Patent Laid-Open No. 62-2.
It is introduced in Japanese Patent No. 11491 and the like and is known.

Further, as a super absorbent polymer having a fine particle size, there is also a resin provided in the form of a water-in-oil type water-swellable polymer emulsion having a particle size of 10 μm or less.

For example, an aqueous solution containing a water-soluble vinyl monomer and a cross-linking agent is injected into an organic dispersion medium containing a hydrophobic surfactant to emulsify, and then polymerized by a radical polymerization catalyst to obtain an emulsion. Further, it is produced by adding a hydrophilic surfactant.

A method for producing these is described in, for example, Japanese Patent Laid-Open No. 63-9.
It is a known one which is introduced in Japanese Patent Laid-Open No. 0537, Japanese Patent Laid-Open No. 63-90510 and the like.

The superabsorbent resin is preferably a spherical superabsorbent resin which swells to a size of 1 to 2 mm. Further, the gel having a higher gel strength in the water-absorbed state is more effective in fluidization when mixed in the soil particles, because the internal friction angle tends to be smaller.

Further, according to the present invention, a water-soluble polymer may be further added.
You may add 05-1.0 weight%.

As the water-soluble polymer to be used, a natural polymer, a semi-synthetic polymer and a synthetic polymer used as a mud additive can be used. Of these, xanthan gum, carboxymethyl cellulose, polyanionic cellulose, hydroxyethyl cellulose, starch, guar gum and guar gum derivatives, which are used as thickeners, are preferable.

[0077]

The present invention uses a water-soluble polymer partially insoluble in water to weaken the cohesive force of clay particles,
In addition to obtaining a clay suspension having a high specific gravity, the partially insoluble part in water has a water-swelling property, so that a clay suspension having a viscosity adjusting effect and a high viscosity can be obtained. It is intended to provide an additive material for a mud pressure type shield construction method which can be excavated even on the ground having a small amount of silt clay and a large amount of gravel and sand without using.

The water-soluble portion of the water-insoluble polymer, which is partially insoluble in water, is cross-linked and adsorbed to the clay particles in the clay suspension to form a slurry-like slurry showing non-Newtonian flow.

The polymer part which is partially insoluble in water also has a strong hydrophilic property and exerts an adsorbing power for water to exert an effect of water absorption thickening in the clay suspension and to increase the viscosity of the system. The aggregate of clay particles in the clay suspension formed by this weak cohesive force and water absorption thickening effect is easily stretched when subjected to a mechanical force, that is, a shearing force, and is deformed in the sheared direction. , The clay suspension exhibits thixotropic behavior.

However, since the cohesive force of the partially insoluble polymer to clay particles is weak, it is possible to increase the amount of clay in the clay suspension and to make a slurry additive with high concentration and high specific gravity. It can be used for ground excavation with a small amount of silt clay and a large amount of gravel and sand.

When mixed with excavated earth and sand, the particles adhere to soil particles having a large internal friction angle such as sand and gravel to reduce the internal friction angle and enhance the fluidity of the excavated earth and sand.

When the additive of the present invention is used for the shield construction method, the injection amount is usually 5 to 150 relative to the volume of excavated earth and sand.
About vol% is used.

[0083]

【Example】

[0084]

[Production Examples 1 to 6] 35% aqueous solution of sodium acrylate 2
28 g, 281 g of 50% acrylamide aqueous solution, 0.009 N'N-methylenebisacrylamide as a crosslinking agent
1 g, 0.3 as isopropyl alcohol as chain transfer agent
g and 0.02 g of t-BHP (t-butyl hydroperoxide) and 91 g of distilled water were mixed in advance to form an aqueous phase.

An oily phase obtained by adding 194 g of an organic dispersion medium (containing 64% by weight of paraffin, 35% by weight of naphthene and 1% by weight of aromatic hydrocarbon) and 15 g of sorbitan monooleate was mixed and emulsified with a homogenizer. .

After emulsification, the mixture was transferred to a four-necked flask, purged with N ₂ and deaerated while stirring. An aqueous solution of sodium metabisulfite was added dropwise while purging with N ₂ to polymerize at a temperature of 50 ° C.

After the polymerization, 16 g of polyoxyethylene lauryl ether was added to obtain a polymer-A. The obtained emulsion has a polymer concentration of 26.4% and an average particle size of 2.
It was 3 μm.

Separately, the amount of N'N-methylenebisacrylamide was changed among the above to obtain polymers B to D and comparative polymers 1 and 2 in Table 1.

[0089]

Example 1 Polymers A to D obtained in Production Example 1 were traded under the trade name "S" in which the clay mineral composition was mainly kaolinite and illite, and the methylene blue adsorption amount was 9.4 meq / 100 g.
A slump was measured by mixing it with a suspension of "CP-A" made of 250 mesh clay and mixing it with a test earth and sand having a gravel rate of 70% as an excavating additive.

The effect of improving the fluidity of earth and sand when the above polymer was kneaded was compared with Comparative Polymers 1 to 2 and bentonite and carboxymethyl cellulose (CMC).

The composition of the test soil is gravel (maximum particle size 20 m
70 wt% of river sand), 27 wt% of fine sand content (river sand with a maximum particle size of 5 mm), 3 wt% of silt and clay content (2 wt% of silica sand with a maximum particle size of 2 mm and 1 wt% of the above clay). Used. The water content ratio was adjusted to 10%.

The viscosity of the drilling additive material at 25 ° C. was measured with a Viscotester (VT-04 type) [manufactured by Rion Co., Ltd.]. The specific gravity is a muddy water specific gravity tester (Mud balance).
It was measured at.

The properties of the mixed earth and sand when the above-mentioned drilling additives were mixed with the test earth and sand at various injection ratios (slurry mixing ratio with respect to the earth and sand and expressed as a volume percentage) were evaluated according to JIS A 11
No. 01 concrete slump test method. Table 2 shows the composition of the drilling additive and the slump test results.

There is no evaluation standard for accurately determining the plastic flow state of excavated soil, and it is generally considered that a slump value of fresh concrete preferably has a consistency of about 8 cm to 15 cm.

Considering based on this criterion, the polymers A to D were able to maintain the consistency of excavated sediment in a wide injection rate range, while the comparative polymer-1 was excavated. The whole is aggregated and does not lose fluidity,
Further, Comparative Polymer-2 lost its cohesion by separating water from the excavated soil and separating the soil.

In CMC, the gravel in the excavated soil was easily separated, and the slump value could not be maintained in a preferable state.

From these results, it is clear that the polymers A to D have the soil improvement effect equivalent to or better than bentonite.

[0098]

[Example 2] Main component of clay: 59 to 67% of SiO ₂ , A
l ₂ O ₃ 17 to 23%, main minerals are kaolinite and montmorillonite, and methylene blue adsorption amount: 23.8 meq
/ 100g, Particle size: 200 mesh or more 86-95%,
Using a product name “Kasaoka Clay” (Kasanen Kogyo Co., Ltd.) having a size of 250 mesh or more and 90%, the difference in the viscosity characteristics between the above-mentioned polymer-A, bentonite and carboxymethyl cellulose (CMC) was compared and examined.

The viscosity characteristics of the prepared clay suspension are fan V
It measured using the G type viscometer. Rotation speed 600, 30
Measured in 6 stages of 0, 200, 100, 6, 3 rpm,
According to the Bingham flow model, the plastic viscosity (cP) and
Bid price (1b / 100ft² ) Was asked.

Each value was calculated as 600 rpm reading minus 300 rpm reading and 300 rpm reading minus plastic viscosity.

The plastic viscosity and the yield value are shown in FIGS.
The viscosity curve of the polymer-A has a larger thickening effect than that of CMC, the plastic viscosity and the yield value increase, and it has been clarified that the thixotropic behavior is a viscosity behavior similar to bentonite. In CMC, the thickening force was insufficient, and the effect of giving thixotropy which works for plastic fluidization of excavated soil was also small.

[0102]

[Example 3] Using the drilling additive according to the present invention, drilling with a pipe extension of 340 m was carried out at a mud pressure type shield construction method construction site having a shield outer diameter of 2400 mm. The excavated ground has a cobble ratio of 85% under a river with a soil coverage of 9 m.
It was the aquifer gravel layer.

A) Soil condition Soil name: Cobblestone mixed gravel layer, maximum particle size: 600 mm Soil type: gravel content 90.8% Sand content 8.9% Silt / clay content 0.3% Wet density: 2.03 g / cm³ Uniformity coefficient: 4.1 Moisture content ratio: 18.3% Permeability coefficient: 3.0 × 10^-2cm / Sec

B) Excavation Result No. 1 of the first embodiment. The drilling additive made with the composition of No. 1 was sent to a shield machine by a pressure pump (tube pump), and was drilled while injecting it into the face from the discharge port. At this time, the inside of the shield machine chamber and the inside of the screw conveyor were filled with the mixed excavated earth and sand, and the mud earth pressure of the mixed excavated earth and sand excavated against the loose earth pressure of the face and the groundwater pressure.

When the injection rate of the drilling additive was 50% to 80%, the slump value at the time of discharge was 8 to 15 c.
It was m and no separation of gravel was observed, and the condition of the discharged sand suitable for the Zuritro type soil discharging method was maintained, and the tunnel excavation was completed smoothly without blockage.

Further, it was confirmed that no water was ejected from the gate port of the screw conveyor even under the river, and that the water content of the drilling additive was good.

The pH of the discharged earth and sand is 7 to 8 except for the vicinity of the starting pit and the arrival pit where the auxiliary method for injecting a highly alkaline water glass-based chemical solution was used, and the pH of the discharged earth and sand was deposited in the adjacent temporary storage site for excavated earth and sand. As a result, after being dried in the sun for about 4 days, the water content fell to 6-8%, which is close to the natural water content. Since this discharged sediment does not contain bentonites, it was treated as the residual soil of non-industrial waste.

[0108]

[Example 4] Using the drilling additive according to the present invention, drilling was carried out at a mud pressure shield construction method construction site having a shield outer diameter of 2000 mm with a pipe extension of 495 m. The excavated ground is covered with 10 m of soil, and the rate of gravel with high collapsibility including boulders is 7
It was a 0-85% aquifer gravel layer.

A) Soil condition Soil name: Pleistocene gravelly soil layer, maximum particle size: 300 mm Soil: gravel content 85% (typical value) Sand content 10% Silt / clay content 5% Wet density: 2.13 g / cm ³ Water content: 10 to 19% Permeability: 10 ^-1 to 10 ^-2 cm / sec

B) Excavation Result No. 1 of Comparative Example 1 The drilling additive made with the composition of No. 1 was sent to a shield machine by a pressure pump (tube pump), and was drilled while injecting it into the face from the discharge port.

Injection was carried out at an injection rate of 60% to 80% of the drilling additive, but the slump value of the drilling earth and sand was 20 to 25 cm.
It is soft, and water and gravel separate, and eruptions often occur,
I was worried about the blockage. The maximum excavation speed was as slow as 2 cm / min, and there was a concern that the construction period would be delayed.

Therefore, in No. 1 of the first embodiment. The slump value was 10 to 1 when changing to the drilling additive made with the composition of 1
It becomes 8 cm, and it becomes possible to maintain the state of discharged sand suitable for the Zuritro type soil discharging method, and it is possible to proceed with tunnel excavation smoothly without causing any eruption or worrying about blockage. It was The average digging speed is 4 cm /
Rose to the minute.

Next, since the ground reached a section with a low hydraulic conductivity and the inflow of groundwater from the face into the shield machine increased, No. 1 of Example 1 was used. For the drilling additive made with the composition of No. 1, bead-shaped super absorbent resin (Diawet AL-
(3, manufactured by Mitsubishi Petrochemical Co., Ltd.) was excavated by adding 1 kg. It was confirmed that no water was ejected from the gate port of the screw conveyor, and that the water resistance of the drilling additive was good.

After that, the ground reaches a section where the gravel rate is large,
The fluidity of excavated soil becomes small, and the slump value is 5-10.
cm, and it became easier for the screw conveyor to close the sheet. 1 kg of a water-soluble polymer, hydroxyethyl cellulose (HEC Daicel, manufactured by Daicel Chemical Industries, Ltd.) was added to the drilling additive made with the composition of No. 1 and drilled.

The gravel in the excavated soil was not separated, and the fluidity in the shield machine chamber and the screw conveyor was improved, and the loose earth pressure of the cutting face and the groundwater pressure could be stably balanced by the mud earth pressure.

The pH of the earth and sand discharged from all the excavation sections is 7 to 8 except for the vicinity of the starting pit and the reaching pit where the auxiliary method for injecting a highly alkaline water glass chemical solution is used, and the water content ratio is also average. Since it was 50%, it was treated as residual soil.

[0117]

[Table 1]

[0118]

[Table 2]

* 1) SCP-A clay for shield, # 25
0, (Bentonite Industry Co., Ltd.) True specific gravity: 2.65, p
H: 5.9, main clay minerals: kaolinite and illite,
Adsorption amount of methylene blue: 9.4 meq / 100 g * 2) Kunigel V1, (Kunimine Industry Co., Ltd.) Yamagata bentonite, particle size 250 mesh, pH: 9.5, main component: SiO ₂ 65-75%, Al ₂ O ₃ 14-17% * 3) GT-5G for shield mud (Shikoku Kasei Co., Ltd.) * 4) Viscotester VT-04 type, rotation speed 62.5r
pm * 5) Mixing ratio of drilling additive material to sediment (volume percentage)

[0120]

According to the present invention as shown in the embodiments,
Even when excavating uneven ground with a small amount of silt clay and a lot of gravel and sand by the mud pressure shield method, high concentration, high specific gravity, and highly viscous excavation are carried out to plastically fluidize the excavated soil and promote stable excavation. The additive material can be prepared, and excavation can be performed without causing problems such as blockage and dust emission.

In the conventional drilling additive material, there is no thickener having a large thickening ability having the same viscosity adjusting ability as bentonite, and the sludge having a high specific gravity has to be used as bentonite, so that it is treated as a large amount of industrial waste. Although the construction cost for treating a large amount of excavated sand was required, by using the present invention, it is possible to apply the mud pressure shield method even in the ground excavation with a large gravel rate, which was conventionally difficult to construct. It is possible to construct a tunnel at low cost.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the polymer addition amount of polymer-A and plastic viscosity.

FIG. 2 is a graph showing the relationship between the polymer addition amount of Polymer-A and the yield value.

FIG. 3 is a diagram showing the relationship between the amount of CMC added and the plastic viscosity of CMC.

FIG. 4 is a diagram showing the relationship between the amount of CMC added and the yield value of CMC.

FIG. 5 is a graph showing the relationship between the amount of bentonite added and the plastic viscosity of bentonite.

FIG. 6 is a graph showing the relationship between the amount of bentonite added and the yield value of bentonite.

Claims (9)

[Claims] 1. A mud pressure formula comprising a viscous sludge composition obtained by adding 0.05 to 1.0% by weight of a water-soluble polymer partially insoluble in water to a clay suspension. Drilling additive for shield method. 2. A drilling additive for a mud pressure type shield construction method, which comprises the slurry composition according to claim 1 containing 0.05 to 1.0% by weight of a superabsorbent resin. . 3. The composition according to claim 1 or 2, and 0.05 to 1 of at least one component selected from the group consisting of water-soluble polymers such as sodium polyacrylate and carboxymethyl cellulose. A drilling additive material for a mud pressure shield construction method, which is composed of a slurry composition added with 0.0% by weight. 4. A polymer obtained by copolymerizing a partially water-insoluble water-soluble polymer with one or more water-soluble vinyl monomers and a crosslinkable monomer as a polymerization raw material by a radical generator, ultraviolet rays, radiation or the like. The drilling additive material for the mud pressure shield construction method according to claim 1, which is a united body. 5. The use amount of the crosslinkable monomer according to claim 4 is 1 ppm to 10 relative to the total amount of the water-soluble vinyl monomer.
The excavating additive for the mud pressure shield construction method according to claim 1, wherein the polymer is 0 ppm (weight ratio), preferably 5 to 30 ppm. 6. The drilling additive for the mud pressure shield construction method according to claim 4, wherein the water-soluble vinyl monomer is a (meth) acrylate-acrylamide polymer. 7. The excavating additive for a mud pressure shield construction method according to claim 6, wherein the content of the (meth) acrylate monomer in the polymer is 20 to 40 mol%. 8. The excavating additive for a mud pressure shield construction method according to claim 4, wherein the polymer is a water-in-oil type reverse phase emulsion. 9. The amount of methylene blue adsorbed on clay (MBC
The excavation additive material for the mud pressure shield construction method according to claim 1, which is a mountain clay having a value of 50 meq / 100 g or less.