JP3085360B2 - Shielding excavation method using siliceous paste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield excavating method for excavating an earth layer while injecting an injection material into a face using a shield type excavator, and using a siliceous paste as the injection material. About.

[0002]

2. Description of the Related Art The inventors of the present invention have developed a shield excavation method using a siliceous paste as an injecting material that does not contain slurry or air bubbles, and has previously proposed the method (JP-A-7-102880). It is a method of excavating using a siliceous paste, which has improved fluidity by crushing siliceous jelly (SiO ₂ ), as an injection material. This method has no pollution problem of earth removal, and if injected and infiltrated between the soil particles and gravel on the face, when the cutter works, it will reduce the internal friction of the ground and reduce the excavation resistance. Of course, due to the fluidity of the siliceous paste itself, the passage resistance when passing through the conveying pipe for conveying to the face is greatly reduced, and the paste can be stably supplied to the face. Further, the fluidity enables the permeation into the face stably irrespective of the presence or absence of cobblestone or the like.

[0003]

However, in a shield excavation method using a siliceous paste as an injecting material,
For the target ground, that is, the ground having abundant groundwater, such as sand, gravel, cobblestone layer, etc., it is necessary to appropriately use a siliceous paste having different performance in accordance with the water content ratio, the gravel ratio, and the like. Therefore, it is necessary to examine the properties of the target ground, such as the gravel ratio, and use the siliceous paste one by one. In addition, since the gravel ratio of the soil layer varies depending on the location, checking it during excavation hinders improvement of work efficiency.

[0004] The object of the present invention is to provide a shielded excavated ground, that is, a ground with abundant groundwater, such as sand, gravel, and a cobblestone layer, which has another performance even if there is a large fluctuation in the water content ratio and the gravel ratio. It is therefore possible to continue the excavation as it is without having to replace it with a siliceous paste.

[0005]

In order to achieve the above object, an invention according to claim 1 of the present application comprises a rotating face cutter, an earth pressure chamber, a stirring means for stirring the excavated shears in the earth pressure chamber, and an earth pressure chamber. A shield excavator having a discharging means for discharging the excavation waste and an injection material introducing means for injecting the injection material into the face, and excavating the soil layer while injecting the injection material into the face face. A fine particle produced by crushing a siliceous aqueous jelly having a silicon dioxide content of 1 to 60% by weight as the injecting material, and intervening between these fine particles to impart fluidity to the whole. A liquid-based silicate paste is used, and a polyacrylate having a molecular weight of 2 to 30 million is added to the silicate paste in an amount of 0.01 to 10 kg / m ³ and used. Ah .

Further, according to the present invention, there is provided a rotating face cutter, an agitating means for agitating an earth pressure chamber, an excavation shear in the earth pressure chamber, a discharge means for discharging the excavation shear in the earth pressure chamber, and an injection material for the face. A shield excavation method for operating a shield-type excavator having an injection material introducing means for injecting, and excavating a soil layer while injecting the injection material into the face face, wherein the silicon dioxide content is as the injection material. Fine particles produced by crushing 1 to 60% by weight of siliceous aqueous jelly;
A silicate paste mainly containing a liquid interposed between these fine particles and having fluidity as a main component is used, and a polyacrylic acid salt is added to the silicate paste to make the face water stoppage and water retention of excavation shears. It is characterized by being used with improved properties.

According to the present invention, the performance of the siliceous paste is improved by adding 0.01 to 10 kg of a polyacrylate having a molecular weight of 2,000,000 to 30,000,000 per 1,000 liters to the siliceous paste. It is improved by the addition of acrylate. That is, the water stoppage of the face and the water retention of the excavation shear are improved as compared with the case where the polyacrylate is not added. Moreover, it is stable with almost no change even if the gravel ratio or moisture content of the ground fluctuates. As described above, since the water retention of the excavation waste is improved, the excavation waste has a very cohesive property. Such property improvement reliably prevents water from spouting from the face. As a result, for example, a siliceous paste used for a sand layer or a gravel layer having a gravel ratio of 70% or less is directly used for excavation of a cobblestone-bearing gravel layer having a gravel ratio of 70% or more by adding the polyacrylate. Becomes possible. In particular, even if the amount of polyacrylate added is increased or decreased, the water retention is almost unchanged and stable.

Accordingly, by using the polyacrylic acid salt-added siliceous paste according to the present invention as an injection material,
The target ground for shield excavation, that is, sand rich in groundwater,
Excavation can be continued as it is without having to replace it with silicic paste of other performance, even if there is a large fluctuation in the water content or the gravel rate, etc.
Work efficiency can be improved and costs can be reduced.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polyacrylate added to a siliceous paste in the present invention improves the water stopping performance of a face and the water retention of excavated shear as compared with a case where excavation is performed only with a siliceous paste not containing it. The purpose is to eliminate the need to use the siliceous paste differently for silicic pastes having different performances depending on changes in soil properties, and from that point of view, specific types of polyacrylate, its molecular weight, the amount of addition, etc. It is determined. However, in ordinary excavation, the type of polyacrylate is sodium polyacrylate, even if there are fluctuations in the water content ratio and the gravel rate, including the ground such as sand, gravel, cobblestone, etc., which are rich in groundwater. Suitable are potassium polyacrylate and ammonium polyacrylate. Particularly, sodium polyacrylate is preferred. The polyacrylate may be a copolymer of sodium acrylate or the like and acrylamide or the like. The molecular weight of polyacrylate is usually 2
If it is between 100,000 and 30,000,000, it can be used for almost the ground. In particular, the range of 5,000,000 to 20,000,000 is stable in terms of the effect. The addition amount of the polyacrylate to the siliceous paste is preferably 0.01 to 10 kg / m ³ in order to achieve the above object. Furthermore, the range of 0.3 to 2 kg / m ³ is good for achieving the purpose, and particularly the range of 0.5 to 1 kg / m ³ is stable.

Next, the siliceous aqueous jelly used in the present invention can be easily obtained by a known method. For example,
Examples thereof include a method in which various acids and salts, for example, sulfuric acid, hydrochloric acid, acetic acid, citric acid, salt, magnesium sulfate, and the like are added to an aqueous solution of a water-soluble silicate such as water glass. Further, a method of gelling an aqueous solution of silicic acid or an oligomer thereof obtained by decationizing an aqueous solution of a water-soluble silicate such as water glass, or a method of gelling an aqueous silica sol by a known method, and the like. No. The content of SiO ₂ is in the range of 1 to 60% by weight, preferably 3 to 30% by weight.
And

The siliceous paste used in the present invention is obtained by crushing the above siliceous aqueous jelly by applying a physical external force sufficient to cause the jelly to break.
Crushing to provide such subdivision can be performed by applying vigorous agitation such as a homogenizer to the jelly at room temperature. As a general rule, the vigorous stirring is preferably continued until fine particles mainly having a particle size of about 300 μm or less are obtained.

As the liquid constituting the siliceous paste,
Water or an aqueous solution or aqueous dispersion to which an inorganic component or an organic component is appropriately added is used as long as the object of the present invention is achieved. By the way, the siliceous aqueous jelly itself contains water, and if the jelly is crushed as it is, a part of the water taken in the jelly is released to the outside. Depending on the type of siliceous aqueous jelly, the paste can have the necessary fluidity with the released water alone, that is, without additional liquid.

Next, a shield excavating method according to the present invention will be described. A long injection line connects the underground shield machine and the siliceous paste supply plant above. The supply plant is connected to the injection line via a pump. The injection line may be provided with a relay pump as needed. A plurality of injection material supply ports are provided on a face plate provided with a face cutter of the shield type excavator. An earth pressure chamber is provided on the front side of the face plate, and a ribbon screw is provided in connection with the earth pressure chamber. An earth pressure gauge is provided in the earth pressure chamber. The rear part of the ribbon screw is a sand plug zone. The earth pressure chamber is filled with excavated cuttings 14 excavated from the face and mixed with the injection material. Excavation waste is discharged from the discharge gate.

The siliceous paste used had a sand layer and a gravel ratio of 7
Appropriate ones were prepared for gravel of 0% or less.
That is, a sol of 15 to 30 weight of SiO ₂ is used as a main material, and 105 liters of this main material and 327 liters of water are mixed.
To this, 33 liters of 5% by volume of H ₂ SO ₄ was added and mixed, and 35 liters of a solution obtained by diluting No. 3 water glass to 40% was added as a hardener and mixed to obtain 500 liters of siliceous jelly. Was. 500 liters of water was added thereto, and the mixture was vigorously stirred, and the jelly was subdivided into fine particles having a particle size of 300 μm or less to obtain a total of 1000 liters of a siliceous paste (hereinafter referred to as a general-purpose paste). This general-purpose paste has an unsuitable performance for a gravel layer mixed with cobblestone having a gravel ratio of 70% or more, and when used for that layer, water may squirt from the face.

(Injection material 1) A material obtained by adding 500 g of sodium polyacrylate having a molecular weight of 15,000,000 to 1,000 liters of the general-purpose paste was used. Here, sodium polyacrylate was dispersed in 500 g of ethylene glycol, added, and stirred.

(Injection material 2) A material obtained by adding 1,000 g of sodium polyacrylate having a molecular weight of 5,000,000 to 1,000 liters of the general-purpose paste was used.

(Injection material 3) A mixture obtained by adding 700 g of sodium polyacrylate having a molecular weight of 20,000,000 to 1,000 liters of the general-purpose paste was used.

(Injection material 4) A material obtained by adding 500 g of potassium polyacrylate having a molecular weight of 15,000,000 to 1,000 liters of the general-purpose paste was used.

(Injection material 5) A mixture prepared by adding 500 g of a copolymer of sodium acrylate and acrylamide (molecular weight: 15 million, molar ratio of sodium acrylate to acrylamide: 7/3) to 1,000 liters of the general-purpose paste was used. .

(Injection material 6) A material obtained by adding 500 g of ammonium polyacrylate having a molecular weight of 10,000,000 to 1,000 liters of the general-purpose paste was used.

(Comparative Example 1 of Injectable Material) The general-purpose paste 10
A solution obtained by adding 500 g of sodium polyacrylate having a molecular weight of 150,000 to 00 liter was used.

(Comparative Example 2 of Injectable Material) The general-purpose paste 10
A solution obtained by adding 5 g of sodium polyacrylate having a molecular weight of 15 million to 00 liter was used.

Using the injection materials 1 to 6, sand rich in groundwater,
When excavation was performed on the ground such as gravel and cobblestone layers, stable excavation was achieved with good water stoppage of the face and water retention of excavated shear. Moreover, it remained stable with little change even if the ground gravel ratio and water content fluctuated. That is, the siliceous paste used for the sand layer and the gravel layer having a gravel ratio of 70% or less can be directly used for excavation of a cobblestone-bearing gravel layer having a gravel ratio of 70% or more by adding polyacrylate. Was.

FIG. 1 is a diagram comparing the excavation speeds of the present invention using the injection material 1 and the conventional product without adding the polyacrylate. The target ground is a gravel ground with a gravel ratio of 70 to 80%.
In the case of the present invention, the excavation speed (mm / min) 55 was 1 time, 65 was 5 times, 70 was 2 times, 75 was 2 times, and 80 was 1 time. The conventional product had an average of 46 for all 12 runs. According to the present invention, it is considered that the water stoppage of the face and the water retention of the excavation shear were improved.

FIG. 2 is a diagram comparing the used amounts of the injection material required for excavating a 2 m diameter and a 1 m length. The present invention averaged 176 liters, whereas the conventional product averaged 29 liters.
5 liters required more than the present invention. FIG. 3 is a diagram comparing cutter torques. 28.2 t ・ m to 100
%, The average of the present invention was 82%, whereas that of the conventional product was 117%, which was higher than that of the present invention.
FIG. 4 shows the change over time in the cutter pressure. It can be seen that the product of the present invention is stable at a lower load than the conventional product.

[0026]

According to the present invention, since a siliceous paste to which polyacrylate is added is used as an injecting material, even if there is a large fluctuation in the water content ratio, the gravel ratio, etc. of the ground to be shielded, other performances can be obtained. The excavation can be continued as it is without having to replace it with the siliceous paste, thereby improving work efficiency and reducing costs.

[Brief description of the drawings]

FIG. 1 is a diagram comparing the excavation speeds of the present invention and a conventional product to which no polyacrylate is added.

FIG. 2 is a diagram showing a comparison between the present invention and the conventional product to which polyacrylate is not added, in terms of the amount of injection material required to excavate a 2 m diameter and a 1 m length.

FIG. 3 is a diagram comparing cutter torques of the present invention and a conventional product to which no polyacrylate is added.

FIG. 4 is a graph showing the change over time in the cutter pressure of the present invention and the conventional cutter without addition of polyacrylate.

Continued on the front page (72) Inventor Masanori Muto 3-7-1, Kandanishikicho, Chiyoda-ku, Tokyo Nissan Chemical Industry Co., Ltd. (72) Inventor Akio Kitagawa 3-7-1, Kandanishikicho, Chiyoda-ku, Tokyo Nissan Chemical Co., Ltd. In-company (56) References JP-A-6-277698 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) E21D 9/06 301

Claims (2)

(57) [Claims] 1. A rotating face cutter portion, an agitating means for agitating an earth pressure chamber, an excavation shear in the earth pressure chamber, a discharging means for discharging the excavation shear in the earth pressure chamber, and an injecting material introducing means for injecting an injecting material into the face. A shield excavation method comprising: operating a shield type excavator having: and excavating an earth layer while injecting an injection material into the face face, wherein the silicon dioxide content of the injection material is 1 to 60% by weight. A fine particle generated by crushing the siliceous aqueous jelly and a siliceous paste mainly containing a liquid interposed between these fine particles and having fluidity as a main component are used, and the molecular weight of the siliceous paste is 2 million to 30 million polyacrylates 0.01 to
A shield excavation method using a siliceous paste, wherein 10 kg / m ^{3 is} added and used. 2. A rotating face cutter portion, an agitating means for agitating an earth pressure chamber, and excavation shears in the earth pressure chamber, a discharging means for discharging the excavation shears in the earth pressure chamber, and an injecting material introducing means for injecting an injecting material into the face. A shield excavation method comprising: operating a shield type excavator having: and excavating an earth layer while injecting an injection material into the face face, wherein the silicon dioxide content of the injection material is 1 to 60% by weight. Fine particles generated by crushing the siliceous aqueous jelly, and a siliceous paste mainly containing a liquid interposed between these fine particles and having fluidity as a main component are used. A shield excavation method using a siliceous paste, wherein a salt is added to improve the water stoppage of the face and the water retention of excavation shear.