JPH08120261A - Shield excavation method in shield tunneling method - Google Patents

Abstract

PURPOSE: To develop a novel shield excavation method whereby the flowability of excavated sediment and the prevention of seepage in excavation are improved in a shield tunneling method. CONSTITUTION: A shield excavation method in a shield tunneling method is developed wherein flowable excavated sediment is mixed with an anionic water- sol. high-molecular substance and then with a cationic water-sol. high-molecular substance or a coagulant to make the sediment nonflowable. Thus, by mixing the excavated sediment with the anionic water-sol. high-molecular substance and then with the cationic water-sol. high-molecular substance or the coagulant, the sediment is agglomerated, dehydrated, and made nonflowable, acting as a cutoff plug against the earth pressure of the natural ground behind the bulkhead of a shield machine and thus decreasing the disturbance of the ground surrounding a shield cutting face and the settlement of the ground surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield excavation method in a shield tunnel excavation method, and more particularly, to a mud pressure shield construction method for sandy or gravel ground where there is a lot of spring water and the face tends to collapse. The shield excavation method in.

[0002]

2. Description of the Related Art In the shield tunnel method, especially the mud earth pressure shield method, an excavating additive mainly composed of clay mineral is sent to the face of a face or a slit opening, and the earth pressure on the face is cut. In order to prevent collapse, it is possible to excavate the soil and excavate it by giving it fluidity so that it can be easily carried out. A general excavating additive used in the conventional mud pressure shield construction method is sludge in which water, clay, bentonite, carboxymethyl cellulose (CMC), etc. are mixed,
It is added to and mixed with the excavated earth and sand to prevent the face from collapsing during excavation, and when excavated earth and sand is carried out, viscosity and fluidity are added to facilitate the carrying out. However, such a conventional construction method has the following problems. (A) The discharged sand becomes soft mud, which cannot be taken out of the construction site by a dump truck as it is. (B) Therefore, it is necessary to use cement-based and lime-based mud improving agents at the construction site for improvement. This improvement not only requires a great deal of cost, but also requires a large space for temporary storage such as one day and night for solidification to progress to an extent that it is easy to carry out and to improve softness. However, it is difficult to secure a large site for equipment for construction in the city area. (C) If there is a lot of groundwater in the ground and the groundwater pressure is high,
Excavated earth and sand will be ejected from the soil discharge port of the soil discharge screw conveyor together with pressure water, and will disturb the ground around the shield face greatly, causing ground subsidence and sinking accidents.

In recent years, a technique for treating excavated soil generated in civil engineering work has been proposed (Japanese Patent Laid-Open No. 63-44097).
issue). This technology produces one or more polymer substances selected from natural water-soluble polymer substances and semi-synthetic water-soluble polymer substances or synthetic water-soluble polymer substances having cohesive property during excavation. It is added to and mixed with the excavated earth and sand, and the whole excavated earth and sand is kept in an agglomerated state. Thereafter, the excavated soil in the agglomerated state is added with hydroxide or water-soluble salt of Group IIa
When a water-soluble salt of Group IIIb or Group IVa is added, these hydroxides or metal ions cause an ionic reaction with the excavated earth and sand or polymer substances, and the whole excavated earth and sand are completely coagulated and solidified. In other words, this technology uses the water solubility, viscosity increase, and water retention of the polymer from the beginning to make the excavated sediment into an agglomerated state, and further reacts it with the divalent or higher valent hydroxide or cation to completely remove the excavated sediment. It is to solidify and solidify. However, in the shield tunnel method, when the excavated soil is given a thickening, water retaining, and aggregating action from the beginning, the workability is significantly deteriorated, and it is necessary to suppress such an action at the beginning. Is hard to adopt. On the other hand, it is necessary to rapidly fluidize the excavated soil when it is carried out, but in the past, at the beginning, the thickening, water retention, and coagulation of the excavated soil were suppressed first, and the excavated soil was rapidly defluidized when carried out. There was no technology available.

Therefore, the present applicants have already proposed a shield excavation method which is very effective in improving the fluidity of excavated soil and the water stoppage during excavation in the shield tunnel construction method, particularly the mud pressure shield construction method. (Japanese Patent Laid-Open No. 3-1290
No. 93). In this method, a water-soluble polymer substance and a boron compound or an aldehyde group-containing compound are added to and mixed with excavated earth and sand, and then an acidic substance or an alkaline substance is added and mixed to make the excavated earth and sand non-fluidized. .

[0005]

As a result of further studies, the inventors of the present invention have found that the shield excavation method of the present invention rapidly immobilizes fluid excavated earth and sand, as in Japanese Patent Laid-Open No. 3-129093. Succeeded in developing a new shield excavation method that can be excavated while minimizing the collapse of the face.
The present invention has been completed.

That is, according to the present invention, in the shield tunnel construction method, an anionic water-soluble polymer substance is added and mixed with an organic solvent suspension in excavated sediment, and then a cationic water-soluble polymer substance and / or a coagulant is added. (EN) A shield excavation method characterized by making fluid excavated sediment non-fluidized by adding and mixing.

One preferred embodiment of the shield excavation method of the present invention is a composition comprising an anionic water-soluble polymer substance, an aqueous solution thereof or water or an organic solvent, while excavating earth and sand behind the partition wall of the shield machine. It is a shield excavation method in which a suspension of fluidity is rapidly made non-fluid by adding and mixing a suspension and then adding and mixing a cationic water-soluble polymer and / or a coagulant.

In another preferred embodiment, an excavation additive containing an anionic water-soluble polymer substance is sent out in front of the partition wall of the shield machine, and the face of the face is excavated while being mixed with the excavated earth and sand and stirred. It is a shield excavation method in which a fluid excavated sediment is made non-fluidized by adding and mixing a cationic water-soluble polymer substance and / or a coagulant while the excavated sediment is carried out to the rear of the partition of the shield machine.

The anionic water-soluble polymer used in the present invention includes alginate, low methoxyl pectin, carrageenan, carboxymethyl cellulose, carboxymethyl starch, carboxymethyl guar gum,
Examples include carboxymethylated polysaccharides such as carboxymethylxanthan gum and carboxymethyl tara gum, which may be used alone or in combination of two or more kinds.

As the cationic water-soluble polymer substance, cationic polyacrylamide, polyethyleneimine, cationic grafted starch, cationic starch,
Examples thereof include cationized polysaccharides such as cationized guar gum, cationized xanthan gum and cationized tara gum, and these may be used in combination of two or more kinds.

The addition amount of the cationic water-soluble polymer substance to the anionic water-soluble polymer substance is such that the weight ratio of the anionic water-soluble polymer substance to the cationic water-soluble polymer substance is 1: 0.01 to 100, The ratio is preferably 1: 0.1-10.

As the coagulant, salts such as lactic acid, phosphoric acid, carbonic acid and gluconic acid such as calcium, magnesium, barium, boron, aluminum and titanium or chlorides such as calcium, magnesium, barium, boron, aluminum and titanium. , Hydroxide and the like.

The amount of the coagulant added to the anionic water-soluble polymer substance is such that the weight ratio of the anionic water-soluble polymer substance to the coagulant is 1: 0.01-10, preferably 1: 0.03-.
Set it to 0.5.

The anionic water-soluble polymer substance may be used as it is, or may be an aqueous solution having an appropriate concentration, or water or an organic solvent such as acetone, glycerin, propylene glycol, 1,3-butylene glycol, polyethylene glycol, a lower alcohol. , High alcohol,
It can be used as a suspension having an appropriate concentration in esters, higher fatty acids, hydrocarbons and fats and oils. The concentration of the anionic aqueous solution polymer substance in the aqueous solution or suspension is not particularly limited.

The water-soluble polymer substance of the present invention includes precipitated fine silica, hydrated silica gel, dehydrated silica gel, natural or synthetic alumina hydrate, natural or synthetic zeolite,
Inorganic substances such as fly ash, sodium silicate, aluminum sulfate, sodium aluminate, calcined gypsum or gypsum dihydrate can be mixed. In addition, fatty acid salts,
Higher alcohol sulfate ester salt, alkylbenzene sulfonic acid and alkyl naphthalene sulfonate, naphthalene sulfonic acid formalin condensate, dialkyl sulfosuccinate, alkyl phosphate salt, polyoxyethylene sulfate salt, polyoxyethylene alkyl ether and polyoxyethylene alkylphenol ether, Mixing one or more surfactants selected from sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene acyl ester, oxyethyleneoxypropylene block polymer, fatty acid monoglyceride, alkylamine salt and quaternary ammonium salt. You can

Further, in order to prevent the discarded excavated soil from decaying and giving off a bad odor, it is possible to mix a fragrance or a deodorant / deodorant. Fragrances include rose oil, jasmine oil, neroli oil, lavender oil, ylang-ylang oil, tuberose oil, clary sage oil, clove oil, peppermint oil, geranium oil, patchouli oil, sandalwood oil, cinnamon oil, coriander oil, nutmeg oil. , Pepper oil, lemon oil, orange oil, bergamot oil, opoponax oil, vetiver oil, orris oil, oak moss oil and other vegetable flavors and musk oil, civet oil, caustium oil, ambergris oil and other animal flavors and limonene, β
-Caryophyllene, cis-3-hexenol, linalool, farnesol, β-phenylethyl alcohol,
2,6-nonadienal, citral, α-hexylcinnamic aldehyde, β-ionone, 1-carvone,
Examples thereof include synthetic fragrances such as cyclopentadecane, linalyl acetate, benzyl benzoate, γ-undecalactone, eugenol, rose oxide, indole, phenylacetaldehyde dimethyl acetal and auranium thiol. Examples of the deodorant / deodorant include cyclodextrin, polymeric metal complexes, plant extracts, abietic acid, stabilized chlorine dioxide, potassium permanganate, activated carbon, and zeolite.

The amount of the anionic water-soluble polymer substance of the present invention to be added to the earth and sand is usually 0.1 to 1 m ^{3 of} earth and sand.
It is 50 kg, preferably 1 to 10 kg. However, this addition amount cannot be uniquely determined and varies depending on the water content of the soil. In other words, the more moisture the soil contains, the softer it becomes and the more fluid it will be. However, depending on the particle size distribution of the sand in addition to the degree of water content, it will be soft and fluid. The degree to which sex is shown varies greatly. The reason is that the coarser the particle size of the soil, the stronger the fluidity of the soil, even with the same water content.

In the method of the present invention, a cationic aqueous solution polymer substance and a coagulant may be used in combination, and in this case, the same weight ratio as the above anionic aqueous solution polymer substance can be used.

[0019]

According to the present invention, in the shield type tunnel construction method, in particular, the mud pressure shield construction method, in the middle of discharging the excavated earth and sand to the rear of the partition wall of the shield machine,
When an anionic water-soluble polymer substance or its aqueous solution or water or an organic solvent suspension is added and mixed, and then a cationic water-soluble polymer substance and / or a coagulant is added and mixed, the water-soluble polymer substances are rapidly mixed with each other. Complexation or agglomeration occurs, which causes agglomeration of the sediment particles, and the excavated sediment that had previously been fluidized rapidly becomes non-fluid and apparently becomes a solidified product. In addition, an excavation additive containing an anionic water-soluble polymer is sent to the front of the bulkhead of the shield machine, the face face is excavated while mixing and stirring with the excavated earth and sand, and then the excavated earth and sand is carried to the rear of the bulkhead of the shield machine. By adding and mixing the cationic water-soluble polymer substance and / or the coagulant during the process, similarly, the water-soluble polymers are rapidly complexed or aggregated with each other, which causes the sediment particles to aggregate. The excavated sediment that had been generated and had fluidity until then rapidly became non-fluidized, and became apparently solidified. With such solid earth and sand, so-called water stop plugs are formed near the outlet of the screw conveyor, so the soil from the screw conveyor outlet that is often encountered when excavating sand gravel ground with high water pressure It is possible to prevent the eruption of, and therefore it is possible to excavate safely and smoothly.

[0020]

The present invention will be described in more detail with reference to examples, but the invention is not limited thereto. Example 1 First, a specific example of the excavation method of the present invention will be described using the attached system diagram shown in FIG. In FIG. 1, 20 is a shield starting shaft, 3 is a shield machine main body, 5 is a rotary cutter thereof, and 21 is a front face of the cutter. The excavating additive used for excavation is prepared by adding and mixing water, clay minerals and sodium carboxymethyl cellulose (CMC) as a thickening stabilizer as needed in the above-mentioned excavating additive preparation plant 1 and mixer 1b. Is prepared.
Then, the additive material is sent out from the slit opening 12 of the rotary cutter 5 to the face 21 of the front face of the shield machine 3 through the transport pipe 11 by the pump 2. The additive material for excavation is necessary for advancing the excavation while preventing the collapse of the face against the earth pressure of the face 21 acting on the front surface of the shield machine, and the earth and sand excavated by the rotary cutter 5 is It is taken into the mixing chamber 4 on the back surface of the rotary cutter 5 together with the additive. The mixing chamber 4 is separated from the working chamber behind the partition 19 in the shield machine 3 by the partition wall 19. In the mixing chamber 4, the excavated soil and the excavation additive are mixed while being pressurized. The earth and sand are given fluidity and taken into the screw conveyor 6 from the inlet of the front half 9 of the screw conveyor 6. The excavated sediment is mixed by the screw conveyor 6 into the mixing chamber 4
In order to be carried out to the rear of the partition wall 19 from the inside, it is required that the soil has fluidity as a necessary property. An excavation additive is required to impart such fluidity to the sand and sand, and particularly when excavating sand and gravel ground, the excavation additive plays an extremely important role in excavability. The soil must have fluidity because it can be easily taken into the screw conveyor 6.

Then, the earth and sand taken into the screw conveyor 6 is discharged from the storage tank 14 of the anionic water-soluble polymer substance or its aqueous solution or water or organic solvent suspension at an appropriate portion of the front half portion 9. The anionic water-soluble polymer substance is fed from the inlet 8 to the screw conveyer 6 through the transport pipe 15 using the pump 7 or the screw conveyer, and is gradually fed to the intermediate portion 9 ′ while being mixed and stirred by the screw. In this intermediate part, a pump 7'is used from the storage tank 14 'of the cationic water-soluble polymer or coagulant, and the cationic water-soluble polymer or coagulant is introduced from the intermediate part inlet 8'of the screw conveyor 6 through the transport pipe 15'. Send in. The earth and sand are gradually sent to the latter half while being mixed and stirred with the additive by the screw. During this time, complexation or agglomeration of the water-soluble polymer substances rapidly occurs, and the earth and sand become non-fluid in an extremely short time.

Since the soil that has become non-fluid has a markedly poor transportability by the screw, in the latter half part 10, the rearward mobility of the sediment in the screw conveyor 6 is gradually decreased, and finally the last part 13 of the conveyor 6. The closed portion of the conveyor 6 is formed by the earth and sand. When such an occlusion is formed, the part in front of it, that is, 1
Therefore, 0, 9 ′, 9 and the mixing chamber 4 are kept in a pressurized state. Therefore, the earth pressure against the cutting face 21 is maintained, the collapse of the cutting face can be prevented, and the cutting face 21 is soiled. Even in the case of water-bearing gravel and sand ground having a large pressure, excavation earth and sand can be safely and smoothly excavated from the rear portion 17 of the screw conveyor 6. Reference numeral 16 is a belt conveyor that conveys the excavated soil to the rear, and 18 is a slide toro.

By this excavation method, sand ground mixed with silt was excavated by the shield method. The composition of the generated excavated sand is 61.7% for gravel and sand, and 38.3 for silt and clay.
%, And the water content ratio was 29.2%. The excavation conditions and results were as follows. Table 1 shows the composition of the additive material for excavation.

[0024]

[Table 1] The amount of anionic water-soluble polymer added to excavated sediment is
The excavated soil was set as shown in Table 2.

[0025]

[Table 2]

Tables 3, 4 and 5 show the evaluation of the excavated sediment containing the cationic water-soluble polymer substance.

[0027]

[Table 3]

[0028]

[Table 4]

[0029]

[Table 5]

Table 6 shows the evaluation of the excavated sediment containing the coagulant.

[0031]

[Table 6]

The cation-grafted starch in Table 4 means starch which is quaternary cation etherified so that the nitrogen content is 0.3%, and poly-3-methacryloxy-2-.
A product obtained by grafting hydroxypropyltrimethylammonium chloride at a graft ratio of 6%. The cationized guar gum in Table 5 refers to a quaternary cation etherified product having a nitrogen content of 1.1%. The addition rate (%) means the percentage of the cationic water-soluble polymer substance or the coagulant with respect to the anionic water-soluble polymer substance. The slump evaluations in Tables 3 to 6 are JIS-A-
According to the concrete slump test method in 1101, the soil was subjected to the improvement treatment instead of the concrete, and the measurement was performed. The measurement is the time from the start of packing the slump corn to the end of packing the soil after the improvement treatment is 3
Pack within 5 minutes, and immediately after packing, gently pull up the slump cone vertically to measure the fall in the center of the improved sediment, use this as the slump, and compare the superiority and inferiority of the improvement effect based on the slump measurement results. did.

When the vehicle is loaded on a dump truck or the like and travels, it is uniquely determined whether or not it is fluidized due to vibration during traveling, or whether it is fluidized while being conveyed by a belt conveyor. It is extremely difficult if the particle size distribution of earth and sand is different, because it will fluctuate drastically, but from the experience of handling many earth and sand in many actual construction works, slump is a rough guideline. Those showing a large value of 7 cm or more can be considered to be soft earth and sand that easily fluidize. Therefore, the slump is 7 cm for shape retention.
The following can be regarded as having good shape retention, and the following criteria were used. ◎ Excellent, ○ Good, △ Fair, × Inappropriate

Embodiment 2 Next, another concrete example of the excavation method of the present invention will be described using the attached system diagram shown in FIG. In FIG. 2, 20 is a shield starting shaft, 3 is a shield machine main body, 5 is a rotary cutter thereof, and 21 is a front face of the cutter. The additive for excavation used for excavation is an anionic water-soluble polymer substance, water, a clay mineral, and sodium carboxymethylcellulose sodium as a thickening stabilizer as necessary in the above-described excavator additive preparation plant 1 and mixer 1b. (CMC) is added and mixed. Then, the additive material is sent out from the slit opening 12 of the rotary cutter 5 to the face 21 of the front face of the shield machine 3 through the transport pipe 11 by the pump 2. The additive material for excavation is necessary for advancing excavation while preventing the collapse of the cutting face against the earth pressure of the cutting face 21 acting on the front surface of the shield machine,
Furthermore, the earth and sand excavated by the rotary cutter 5
It is taken into the mixing chamber 4 on the back surface of the rotary cutter 5 together with the additive. The mixing chamber 4 is provided with a partition 19 so that the partition 1 in the shield machine 3
9 is separated from the work chamber behind, and in the mixing chamber 4, the excavated earth and sand and the excavation additive are mixed while being pressurized, and the earth and sand are given fluidity,
It is taken into the screw conveyor 6 from the inlet of the first half 9 of the screw conveyor 6. The excavated earth and sand from the mixing chamber 4 is separated from the partition wall 1 by the screw conveyor 6.
In order to be carried out to the rear of No. 9, it is required that the soil has fluidity. An additive material for excavation is required to impart such fluidity to earth and sand,
Especially when excavating gravel ground, the additive material for excavation plays an extremely important role in excavability. The soil must have fluidity because it can be easily taken into the screw conveyor 6.

Then, in the earth and sand taken into the screw conveyor 6, in an appropriate portion of the first half portion 9, a cationic water-soluble polymer substance or a coagulant storage tank 1
A cationic water-soluble polymer substance or a coagulant is fed from an inlet 8 to the screw conveyor 6 through a transport pipe 15 'using a pump 7'from 4'. The earth and sand are gradually mixed with the additive by the screw and stirred, and gradually the latter half 10
Will be sent to. During this time, complexation or agglomeration of the water-soluble polymer substances rapidly occurs, and the earth and sand become non-fluid in an extremely short time. Since the soil that has become non-fluid has markedly deteriorated transportability by the screw, the mobility of the soil in the screw conveyor 6 toward the rear gradually decreases in the latter half 8 and finally the final portion 13 of the conveyor 6
The closed portion of the conveyor 6 is formed by the earth and sand. When such an occlusion is formed, the front portion, that is, 10, 9 and the mixing chamber 4 is formed.
Therefore, the pressurized state is maintained, and therefore, the earth face counter pressure is maintained also on the face 21, so that the face face can be prevented from collapsing and the face face 21 has a large soil pressure. Also, the rear part 1 of the screw conveyor 6
From 7, the excavated earth and sand can be safely and smoothly excavated without spouting. Reference numeral 16 is a belt conveyor that conveys the excavated soil to the rear, and 18 is a slide roller.

By this excavation method, sand ground mixed with silt was excavated by the shield method. The composition of the generated excavated sand is 61.7% for gravel and sand, and 38 for silt and clay.
It was 3%, and its water content ratio was 29.2%. The excavation conditions and results were as follows. Table 7 shows the formulation of the additive material for excavation.

[0037]

[Table 7]

The type of anionic water-soluble polymer and the amount added to the additive for excavation were set as shown in Table 8 for excavated soil.

[0039]

[Table 8]

Tables 9, 10 and 11 show the evaluation of excavated sediment containing the cationic water-soluble polymer substance.

[0041]

[Table 9]

[0042]

[Table 10]

[0043]

[Table 11]

Table 12 shows the evaluation of the excavated sediment containing the coagulant.

[0045]

[Table 12]

Cation-grafted starch in Table 10 means starch which has been quaternary cation-etherified to have a nitrogen content of 0.3%, and poly-3-methacryloxy-2-.
A product obtained by grafting hydroxypropyltrimethylammonium chloride at a graft ratio of 6%. The cationized guar gum in Table 11 refers to a quaternary cation etherified product having a nitrogen content of 1.1%. The addition rate (%) means the percentage of the cationic water-soluble polymer or the coagulant with respect to the anionic water-soluble polymer. The slump evaluations in Tables 9 to 12 are JIS-A.
According to the concrete slump test method in -1101, the soil and sand subjected to the improvement treatment were used instead of the concrete. The slump cone was packed with the improved soil and sand so that the time from the start of filling to the end of filling was within 3 minutes, and immediately after the filling, the slump cone was gently pulled up vertically, and the center of the improved soil The slump was measured for the drop in the part and the superiority and inferiority of the improvement effect was compared with the slump measurement results.

Further, when the vehicle is loaded on a dump truck or the like and travels, it is uniquely determined whether or not it fluidizes due to vibration during traveling, or whether it fluidizes while being conveyed by a belt conveyor. It is extremely difficult if the particle size distribution of earth and sand is different, because it will fluctuate drastically, but from the experience of handling many earth and sand in many actual construction works, slump is a rough guideline. Those showing a large value of 7 cm or more can be considered to be soft earth and sand that easily fluidize. Therefore, the slump is 7 cm for shape retention.
The following can be regarded as having good shape retention, and the following criteria were used. ◎ Excellent, ○ Good, △ Fair, × Inappropriate

[0048]

According to the present invention, when an anionic water-soluble polymer substance is mixed with excavated sediment, and then a cationic water-soluble polymer substance and / or a coagulant is added and mixed, the excavated sediment is aggregated, dehydrated, Make it non-fluidized. Then, the excavated earth and sand filled in the rear part of the screw conveyor fulfills the function of a water blocking plug against the earth pressure of the natural ground, and has the effect of reducing the disturbance of the natural ground around the shield face and reducing the subsidence of the ground. Moreover, since the discharged soil is aggregated and dehydrated so that it can be carried out as it is by a dump truck, there is no need for equipment for improving excavated soil, its site, and an improving agent. Therefore, economical construction is possible in a small construction site.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a mud pressure shield excavating additive preparation plant, its piping, and a shield machine.

FIG. 2 is a system diagram showing another example of a mud pressure shield excavating additive preparation plant, its piping, and a shield machine.

[Explanation of symbols]

1: Drilling additive preparation plant (viscosity, water, CMC storage, metering, input equipment to mixing mixer) 1b: Drilling additive mixing mixer 2: Drilling additive pressure injection pump 3: Shield excavator 4 : Mixing chamber 5: Rotating cutter 6: Screw conveyor for soil removal 7: Pump for adding anionic water-soluble polymer 7 ': Pump for adding cationic water-soluble polymer or coagulant 8: Addition of anionic water-soluble polymer Hole 8 ': Addition hole for cationic water-soluble polymer or coagulant 9: Screw conveyor first half 9': Screw conveyor middle 10: Screw conveyor second half 11: Excavation additive transport pipe 12: Excavation additive discharge Outlet 13: Water stop plug forming part of screw conveyor 14: Anionic water-soluble polymer storage tank 14 ': Cationic water-soluble polymer or coagulation Solid agent storage tank 15: Transport pipe for anionic water-soluble polymer 15 ': Transport pipe for cationic water-soluble polymer or coagulant 16: Belt conveyor for earth removal 17: Screw conveyor outlet for earth removal 18: Discharge Soil transporting Toro

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Sasaoka 1-2-2 Akaashiadai, Mita-shi, Hyogo (72) Inventor Toru Nakajima 1-49, Tominato-cho, Sakai-shi, Osaka (72) Inventor Tatsuya Kishida Hyogo 2-210 Higashi-Sonoda-cho Amagasaki City HANA House No. 203

Claims (8)

[Claims] 1. In the shield tunnel construction method, an anionic water-soluble polymer substance is added to and mixed with the excavated earth and sand, and then a cationic water-soluble polymer substance and / or a coagulant is added and mixed, whereby fluid excavated earth and sand is added. A method for excavating a shield, characterized in that it is made non-fluidizing. 2. An anionic water-soluble polymer substance or its aqueous solution or water or an organic solvent suspension is added and mixed while the excavated soil is carried out behind the partition wall of the shield machine, and then the cationic water-soluble polymer substance is added. The shield excavation method according to claim 1, wherein the fluid excavation soil is made non-fluidized by adding and / or mixing a coagulant. 3. An anionic water-soluble polymer substance is sent out in front of the partition wall of the shield machine to excavate the face face while mixing and stirring with the excavated earth and sand, and then while the excavated earth and sand is carried out to the rear of the partition wall of the shield machine. The shield excavation method according to claim 1, wherein the fluid excavated earth and sand is made non-fluidized by adding and mixing a cationic water-soluble polymer substance and / or a coagulant. 4. The anionic water-soluble polymer substance is alginate, low methoxyl pectin, carrageenan, carboxymethyl cellulose, carboxymethyl starch, carboxymethyl guar gum, carboxymethyl xanthan gum or carboxymethyl tara gum.
3. The shield excavation method according to any one of 3 above. 5. The cationic water-soluble polymeric substance is cationic polyacrylamide, polyethyleneimine, and cationic grafted starch, cationic starch, cationic guar gum, cationic xanthan gum or cationic tara gum. The shield excavation method according to item 1. 6. The coagulant is a salt of lactic acid, phosphoric acid, carbonic acid or gluconic acid with calcium, magnesium, barium, boron, aluminum or titanium or a chloride or hydroxide of calcium, magnesium, barium, boron, aluminum or titanium. It is a thing, The shield excavation method of any one of Claims 1-3. 7. An anionic water-soluble polymer substance to be added:
The weight ratio of the cationic water-soluble polymer is 1: 0.01-
It is 100, The shield excavation method of any one of Claims 1-6. 8. An anionic water-soluble polymer substance to be added:
The weight ratio of the coagulant is 1: 0.01-10.
6. The shield excavation method according to any one of 6 above.