JP2571446B2 - Tail seal composition for shield machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tail seal composition for stopping groundwater entering from a tail seal portion of a shield excavator to which high water pressure is applied when excavating an underground tunnel. Things.

[Prior art] Urban tunnels in urban areas are now used in large underground structures such as subways, underground shopping centers, underground parking lots,
Communal trenches or tunnels for communication, electric power, gas, etc. are complicated, and the tunnel position is becoming deeper. Along with that, the construction method has been replaced by the tunnel method mainly based on the shield method.

An excavator is used for excavation in the tunnel method. In this excavator, a wire brush or a wire net is mixedly mounted on a tail seal portion of the excavator in order to prevent water or earth and sand from entering the excavator. However, in the case of deep soil or the seabed, it is difficult to completely stop water with only the brush or the net due to high water pressure.

For this reason, a seal agent made by kneading a polymer-based water-absorbing swelling agent with grease in a wire brush or a wire net of the tail seal portion (Japanese Utility Model Application Laid-open No. 63-181696), and a seal agent in which a pigment, a metal, and a synthetic resin are mixed into grease (particularly, 63-315798)
Sealant in which liquid resin, asbestos and synthetic fiber are mixed in hydrocarbon oil and hydrocarbon oil (JP-A-62-190280)
It has been proposed to improve the water stopping effect by press fitting.

However, these former two types of sealants still have an insufficient water stopping effect for use at high depths, and the third type has a problem in safety because asbestos is an essential component.

[Problem to be Solved by the Occurrence] The present invention focuses on the fact that the cut fiber promotes the entanglement action with the wire brush or the wire net by mixing the cut fiber, and aims at overcoming the drawbacks of the sealant described above. As a result of research, the combination of long and short fibers and talc entangles the side of long fibers, short fibers and talc with wire brushes and wire nets to form a dense structure of wire brushes and wire nets. The present inventors have found that the water stopping effect under water pressure is improved, and have completed the present invention.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tail seal composition for promoting a sticking retention action of a sealant on a wire brush or a wire net of an excavator tail seal portion.

[Means for Solving the Problems] That is, the present invention provides (1) base oil or grease, based on the total amount of the composition, (2) 20 to 60% by weight of talc, and (3) synthetic fiber having a fiber length of 1 to 15 mm. And / or (4) 0.5 to 10% by weight of a synthetic fiber and / or a natural fiber having a fiber length of less than 1 mm as essential components. It provides things.

Hereinafter, the tail seal composition according to the present invention will be described in detail.

(1) Mineral oil is preferably used as the base oil. As the mineral oil, a lubricating oil is usually used. For example, lubricating oil fraction obtained by distilling mineral oil at normal pressure, solvent removal, solvent extraction, hydrocracking, solvent dewaxing, hydrodewaxing, sulfuric acid washing, clay refining, hydrorefining, etc. Purified by appropriate combination is used. Synthetic oils such as poly-α-olefins, alkylbenzenes, esters, and polyethers can also be used, but the use of mineral oils is more economical. The viscosity range of the base oil is not particularly limited, but any viscosity range can be used as long as it is within the range of a commonly used lubricating oil. The desirable viscosity range is
Those with 6 to 1000 cSt at 40 ° C can be used optimally. on the other hand,
As grease, a thickener is compounded with the above base oil, and the type of the thickener may be any of a metallic soap such as lithium soap and calcium soap, a complex soap, a non-soap such as Benton and urea. May be used,
Considering economy, metal soap based thickeners such as lithium soap and calcium soap are preferred. The amount of the thickener is not particularly limited, and is appropriately determined depending on the amount and consistency of (2) talc and (3) (4) fibers, but is usually 5% by weight or less based on the total amount of grease. It should be noted that the oil retention of the tail seal composition is better when grease is used than when the base oil is used alone.

(2) Talc is mixed up to 20 to 60% by weight, preferably 30 to 50% by weight, based on the total amount of the composition. If it is less than 20% by weight, the desired water pressure resistance cannot be obtained, and 60% by weight
If the ratio exceeds 2, the tail seal composition becomes brick-like, which is not preferable. The particle size of talc is not particularly limited, and for example, a particle having an average particle size in the range of 5 to 50 μm may be used.

(3) (4) As the fiber, polyolefin (polyethylene, polypropylene, etc.), polyamide (nylon, etc.), polyvinyl alcohol (vinylon, etc.), rayon, acetate, polyester (polyethylene terephthalate, etc.), polyacryl (polyacrylonitrile, etc.), Among synthetic fibers such as polyvinyl chloride and polyvinylidene chloride or natural fibers such as cotton yarn, silk, wool and hemp, fibers having a fiber length of 1 to 15 mm, preferably 2 to 10 mm (hereinafter referred to as long fibers) and a fiber length of less than 1 mm Preferably, less than 1 mm to 0.001 m
m fibers (hereinafter referred to as short fibers), and one or more of long fibers and short fibers can be used. The thickness of these fibers is not particularly limited, but is preferably in the range of 0.5 to 20 denier.

The content is 0.5 to 10% by weight with respect to the total amount of the composition together with the long fibers and the short fibers, but preferably 1 to 6% each.
% By weight. If any one of the long fibers and short fibers is less than 0.5% by weight, the desired water resistance cannot be obtained, and if any one of the long fibers and short fibers exceeds 10% by weight, the pumping performance of the pump is hindered. .

The components (1) to (4) are mixed with a usual mixer, and the consistency is usually adjusted to 200 to 350, preferably 250 to 310. When the consistency is less than 200, the pumpability of the pump is impaired, and when it exceeds 350, desired water resistance cannot be obtained. In addition, by mixing talc, the specific gravity of the tail seal composition can be made larger than that of water, and the problem that the sealant at the time of infiltration of groundwater, which often occurs with the conventional grease-based sealant, is removed. . The specific gravity is preferably from 1. to 2.0. When the specific gravity is less than that, inorganic substances such as calcium carbonate, calcium sulfate, magnesium carbonate, barium carbonate, barium sulfate, and zinc oxide may be added.

It goes without saying that various colorants, antioxidants, rust inhibitors and the like may be mixed in addition to the above-described compositions.

EXAMPLES Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples.

Examples 1 to 3 Mineral oil (@ 40 ° C., 100 cSt) with a thickness of 5 denier and a length of 1 to 1
9mm rayon, 1 denier thick, cotton thread less than 1mm long,
And a predetermined amount of talc having an average grain size of 9.2 μm,
A tail seal composition having the composition shown in the table was obtained.

Examples 4 to 6 A base grease was synthesized from mineral oil (@ 40 ° C., 485 cSt) and lithium 12-hydroxystearate, to which 3 deniers, 2 to 8 mm long nylon, 0.5 denier, less than 1 mm long And talc having an average particle size of 33.5 μm were mixed in predetermined amounts to obtain a tail seal composition having the composition shown in Table 1.

Comparative Examples 1 to 9 For comparison, mineral oil (@ 40 ° C., 100 cSt) in 5 denier, rayon 1 to 9 mm in length, 1 denier in thickness, 1 mm in length
Talc with an average particle size of 9.2 μm
A mixture of only the components (Comparative Examples 1 to 3), mineral oil (# 40
C, 485 cS) and a base grease obtained from lithium 12-hydroxystearate (Comparative Example 4), a nylon having a thickness of 3 denier, a length of 2 to 8 mm, a thickness of 0.5 denier, a tetron having a length of less than 1 mm, A talc having an average particle size of 33.5 μm in which only two components are mixed (Comparative Examples 5 to 5)
Table 1 shows the compositions of 7) and two commercially available sealants (Comparative Examples 8 and 9).

The following evaluation tests were performed on these tail seal compositions, and the results are also shown in Table 1.

<Evaluation Test> 1. Consistency The penetration consistency (60 w) was measured in accordance with the JIS K2220 5.3 consistency test method.

2. Water pressure test Figure 1 shows the outline of the water pressure test device.

Ten 20-mesh wire nets are fixed to the bottom of a cylindrical metal container, and the tail seal composition is poured into a layer thickness of 50 mm. After 50 cc of water was sealed thereon and allowed to stand for 10 minutes under a nitrogen pressure of 30 kgf / cm ² , the amount of the tail seal composition protruding from the wire net was measured.

[Effects of the Invention] As is clear from the results shown in Table 1, all of the tail seal compositions according to the present invention have a small amount of leakage in a water resistance test and have excellent performance. On the other hand,
(Among compositions (Comparative Examples 1 to 7) and commercially available sealants (Comparative Examples 8 and 9) out of the components (2) to (4), Alternatively, the wire mesh is broken, and the performance is clearly inferior to the composition of the present invention.

As described in detail above, the table seal composition of the present invention is a composition having an excellent water stopping effect under high water pressure.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a water pressure resistance test apparatus used in Examples and Comparative Examples.

Claims (1)

(57) [Claims] 1. The following four components, (1) base oil or grease, based on the total amount of the composition, (2) 20 to 26% by weight of talc, (3) synthetic fiber and / or natural fiber having a fiber length of 1 to 15 mm A tail seal composition for a shield machine, comprising as essential components 0.5 to 10% by weight, and (4) 0.5 to 10% by weight of synthetic fibers and / or natural fibers having a fiber length of less than 1 mm.