JPH0782559A - Slurrying material for earth pressure balanced shield driving method and earth pressure balanced driving method - Google Patents

Abstract

PURPOSE:To obtain a slurring material improved in water retention, lubricating properties and flow by mixing water with a specified water-soluble organic polymeric compound and clay. CONSTITUTION:The material is prepared by mixing water with 1-80vol.% at least one water-soluble organic polymeric compound selected from among polysodium acrylate, polyacrylamide, carboxymethylcellulose, sodium carboxylmethyl cellulose, sodium alginate, PVA, starch, etc., and 100vol.% clay.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mud material used for earth pressure system shield construction method and earth pressure system propulsion construction method in tunnel excavation.

[0002]

2. Description of the Related Art In closed-type mechanical excavation, mud material is injected into the face of a face to pressurize the face to ensure stability of the face and to improve its transportability by mixing the mud material with the excavated soil. Is being done. A viscous suspension containing water and clay such as bentonite as main constituents is used as a conventional mud additive. However, since this mud material is a fine particle type high-concentration mud material, the equipment becomes large in the excavation of sand and gravel, and since it thickens with time, the pressure loss in pumping becomes large, and the cement However, there are drawbacks such as separation of earth and sand, reduction of earth pressure, and spouting from a screw due to the agglomeration phenomenon due to the inclusion of salt.

Other mud-adding materials include those using inorganic fibers and pulp fibers as typical fibrous substances. However, since it is impossible to mix it in a large amount due to the large size of the fiber, sufficient water retention and lubricity cannot be obtained, and it easily separates from water and the water retention of the mud additive alone is I had a bad problem.

[0004] In recent years, mud-adding materials in which water is mixed with a water-swelling polymeric substance have been developed. However, there are drawbacks in that they are dissipated by pressurization during excavation of sand and gravel, the viscosity is lowered, and dehydration is carried out after mixing excavated soil. Yes, it is not satisfactory as a mud material. Furthermore, in order to solve these drawbacks, a mud material for an earth pressure type shield construction method in which water and a high molecular polymer silicate are mixed has been proposed (see JP-A-4-202998). However, according to this, when adjusting by adding water, it becomes a powdery powder, the viscosity decreases in 1 to several days,
It has been pointed out that there are problems such as dehydration of the mixture with excavated soil.

[0005]

From the above, there is a demand for this type of mud material that has more excellent water retention and lubricity and does not deteriorate in function. An object of the present invention is to provide a mud material which is excellent in water retention, lubricity or fluidity in a state of being mixed with excavated earth and sand and has no functional deterioration.

[0006]

Means for Solving the Problem
A mixture of one or more water-soluble organic polymer compounds such as sodium polyacrylate, polyacrylamide, carboxymethyl cellulose, sodium carboxymethyl cellulose salt, sodium alginate, polyvinyl alcohol, starch, and clay. Is. The clay is not particularly limited, but it is preferable that the clay contains more montmorillonite. For example, any of bentonite, clay, kaolin, kibushi clay, geimelo clay and the like may be used, but bentonite is more preferable. The amount of the water-soluble organic polymer compound added varies depending on the type of the water-soluble organic polymer compound and the type of clay and is not particularly limited, but is about 1 to 80 with respect to 100 of the clay in volume ratio.

[0007]

When the water-soluble organic polymer compound and clay are mixed in water, it does not become powdered and swells in a short time to form a viscous mud material. The water-soluble organic polymer compound acts as a thickener and, in some cases, a water retention agent. Clay is an aggregate of hydrated silicate minerals formed by chemical changes due to weathering of rocks. The chemical components are mainly silicon, aluminum, iron, magnesium,
Alkali metals, alkaline earth metals and water. Since clay is composed of an aggregate of fine particles (colloidal particles) having a diameter of 2 μm or less, it exhibits remarkable colloidal properties such as adhesiveness, plasticity, adsorptivity, swelling property and ion exchange property. The present invention utilizes this colloidal property. Among clays, bentonite is composed of SiO ₂ and Al ₂ O ₃ as main components, has a layered molecular structure remarkably developed, and has a high content of montmorillonite having high colloidal properties. It is also characterized by having a particularly large swelling property among clay minerals. This montmorillonite is an effective component for improving the function of the mud additive of the present invention.

The mud additive of the present invention forms a microfibrous substance by the dissolved and swollen water-soluble organic polymer compound and clay. This fibrous substance is produced by a coagulation reaction when a water-soluble organic polymer compound and clay are dissolved and swollen in water, and usually has a length of several microns to several millimeters. This fibrous substance works effectively. When using this mud material for earth pressure system shield method or earth pressure system propulsion method,
The mud material and excavated soil are mixed to form mud, and the fibrous material is mixed between the soil particles of the excavated soil. Even if the mud receives pressure from the thrust of the jack and comes into pressure contact with the ground, the mud material does not move to the ground side. This is because when the mud material reaches the rock surface, the fibrous material and water are separated on the rock surface in the initial stage, only water slightly moves to the rock surface side, and the fibrous material remains on the rock surface. This is because the fibrous substance forms an impermeable film on the ground surface. For this reason, when the mud material is injected into the ground such as a sand layer or a gravel layer that contains almost no water, it acts to prevent the mud material from being absorbed by the ground, When is injected into the ground such as a sediment layer having a high water content ratio or a sediment layer in which groundwater flows, it acts to prevent the mud material from being diluted and its function lowering. Therefore, after that, neither the mud material nor the water migrated to the ground side due to the impermeable membrane, and the free water on the ground side did not migrate to the excavated soil side, and the ground became stable. , Brings stability of the face.

In addition, in the excavated soil mixed with the mud additive, the adhesive force between the soil particles is reduced, the bond between the soil particles is broken and deformed by a slight external force, and when an external force is further applied, the soil excels continuously. It will become deformed. In other words, the plasticity of excavated soil increases. And, since the fibrous substance has a large water retention, there is no dehydration from mud, the composition fluidity is maintained, there is no blockage in the chamber, the torque of the cutter or the screw conveyor is reduced, and the inside of the mud pipe Friction resistance is also reduced. The mud material of the present invention is used by appropriately changing the mixing ratio of water and other components depending on the soil quality. For example, soil with a lot of sand can contain a large amount of clay, and soil with a clay can contain a small amount of clay.

[0010]

An embodiment of the present invention will be described below. As a water-soluble organic polymer compound, sodium polyacrylate 3 kg,
Carboxymethyl cellulose soda salt 3Kg and clay 14
Kg and 1,000 liters of water are mixed and stirred well to disperse. After about 10 minutes, the viscosity becomes 3,000 cps.
A viscous mud material can be obtained. For comparison with this example, as a comparative example, a water-soluble organic polymer compound was removed from the formulation of the above-mentioned example, and a mud material was prepared in which clay was increased to 100 kg. Its viscosity was 3,000 cps. The contents and results of a comparative test of water retention and lubricity for both of these are shown below.

For the water retention test, as shown in FIG. 1 (a), a stainless steel cylindrical pressure vessel 1 having an inner diameter of 76 mm and a length of 150 mm was used. The container 1 is formed of a removable bottom plate 2 having a drainage port 8 at the bottom, a 60-mesh wire net 3 whose peripheral portion is fixed by the bottom plate 2, and a filter paper 4 arranged above the wire net 3 and fixed together with the wire net 3. The upper part has a compressed air supply port 5 and is closed airtight by a lid 7 provided with a pressure gauge 6. In the water retention test, the container 1 was separately stored with the same amount of the added mud material of the example and the comparative example, and 3
The air pressure of kg / cm ² was applied to measure the amount of filtered water flowing out from the drainage port 8 during the first 30 minutes. The results are shown in Table 2. From these results, it can be seen that in the examples, the fibrous substance greatly contributes to the action of blocking the outflow of water by closing the eyes of the filter paper, and that the water retention is excellent.

For the lubricity test, as shown in FIG. 1 (b), a container 1a in which the bottom of the container 1 was replaced was used.
The bottom of the container 1a has a structure in which a rotary shaft 9 penetrates, a rotary body 10 is provided at the inner end of the rotary shaft 9, and a rotary drive unit 12 having a torque detector 11 is provided outside. The lubricity test was carried out by preparing a mixture of the test mud of which physical properties are shown in Table 1 and mixing the mud additive of the example and the mud additive of the comparative example in an amount of 20% by volume and separately in the container 1a. 1kg / c
The torque was measured by applying air pressure of m ² . The results are shown in Table 2. From this result, it is understood that the example has better lubricity than the comparative example.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

The mud additive of the present invention is superior to the conventional mud additive in water retention, fluidity or lubricity when used in the earth pressure shield method and the earth pressure propulsion method. ,
When the mud material is mixed with the excavated earth and sand, it maintains the water stop between the excavated soil side and the ground with the cutting face as a boundary, so that the stability of the cutting face can be secured and the fluidity of the excavated sand and sand is improved, Since the adhesive force of the excavated earth and sand is reduced, the excavated earth and sand can be easily discharged. Further, since the excavated earth and sand can be easily discharged, the drive unit of the device for discharging the excavated earth and sand can be downsized, and energy consumption can be reduced.

[Brief description of drawings]

FIG. 1 shows a schematic structure of an apparatus used for a comparative test of an example of the present invention and a conventional example, (a) is a longitudinal sectional view of a lubricity test apparatus, and (b) is a longitudinal section of a lubricity test apparatus. It is a figure.

[Explanation of symbols]

 1 Container 1a Container 3 Wire Mesh 4 Filter Paper 8 Drainage Port 10 Rotating Body 11 Torque Detector

 ─────────────────────────────────────────────────── ─── Continuation of front page (71) Applicant 593189140 Takashi Kamada 60-30, Nishinakaji, Yatomi-cho, Kaifu-gun, Aichi Prefecture 60-30 (72) Inventor Atsushi Maeda 2-4 Takazukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture No. Matsumura Sekiyu Kasei Co., Ltd. (72) Inventor Kazuo Ito Gonosan, Yatomi-cho, Aichi Prefecture, Goto-san, 5 letters 269 5 (72) Inventor Takashi Kamada Yatomi-cho, Kaifu-gun, Aichi Pref. Nishinakaji Gogo 60 − 30

Claims (1)

[Claims] 1. In water, one or more selected from the group of water-soluble organic polymer compounds such as sodium polyacrylate, polyacrylamide, carboxymethylcellulose, sodium carboxymethylcellulose, sodium alginate, polyvinyl alcohol, and starch, Earth pressure system shield method and clay additive mixed with clay for earth pressure system propulsion method.