Tail seal composition for shield tunneling machine and shield tunneling method

Abstract

To provide a tail seal composition capable of maintaining a good water cut-off property for a long time.SOLUTION: A tail seal composition for a shield boring machine comprises: [A] a lubricant base oil; [B] inorganic powder; [C] a high molecular weight polymer; and [D] fibers, and the tail seal composition in which the high molecular weight polymer has a weight average molecular weight of 35,000 to 400,000 can solve above problems.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tail seal composition for a shield tunneling machine. More specifically, it relates to a tail seal composition for a shield tunneling machine that can maintain water stoppage performance for a long time. The present invention also relates to a shield tunneling method using this tail seal composition for a shield tunneling machine.

Background Art

[0002] When tunneling underground with a shield tunneling machine, the shield tunneling machine advances while excavating the ground in the advancing direction. Behind the shield tunneling machine, segments that will form the inner wall of the tunnel are sequentially assembled. In this case, the outer diameter of the tunnel to be excavated (excavation opening diameter) is the outer diameter of the shield tunneling machine plus a margin (several centimeters) for the shield tunneling machine to advance. Since the segments are assembled inside the shield tunneling machine, the outer diameter of the segments is equal to or less than the inner diameter of the shield tunneling machine. Therefore, a gap is generated between the outer diameter of the tunnel and the outer diameter of the segments behind the shield tunneling machine. This gap is filled with a backfill material as the shield tunneling machine advances.

[0003] On the other hand, at the rear end of the shield tunneling machine, groundwater and the like seep into the unfilled void in the tunnel. To prevent this groundwater from entering the shield tunneling machine, a plurality of brush seals for water stoppage between the outer periphery of the segments inside the shield tunneling machine and the inner periphery of the shield tunneling machine are provided on the inner periphery of the shield tunneling machine at the end. And in order to maintain its water stoppage performance, a tail seal composition is filled between these brush seals. As the shield tunneling machine advances, the tail seal composition of the brush seal adheres to the outer peripheral surface of the segment and dissipates to the ground. Therefore, it is necessary to replenish the tail seal composition to the brush seal part, and the tail seal composition is pumped through a pipe using a pump.

Prior Art Documents

Patent Documents

[0004] Patent Document 1 Pamphlet of International Publication No. 2016 / 021690 Summary of the Invention Problems to be Solved by the Invention

[0005] The tail seal composition mechanically always feeds a certain amount into the tail seal part during operation. However, during weekdays at night and on holidays, etc., the feeding of the tail seal composition often stops. In that case, the tail seal composition is not newly fed and remains in the tail part. However, even in that case, it is considered that the pressure due to groundwater is applied. Therefore, a tail seal composition that can stop water without problems even when pressure is applied for a long time is required. Means for Solving the Problems

[0006] Conventionally, the water-stopping property of the tail seal composition has been evaluated by the presence or absence of outflow water after pressurization for a short time, for example, 5 minutes (Patent Document 1). However, the present inventors have found that even when a good evaluation of water-stopping property is obtained in a short-time evaluation, leakage may occur in a long-time test. The present inventors have earnestly studied a tail seal composition capable of maintaining water-stopping property for a long time. And the present inventors have found that by adopting the following configuration, the above problems are solved and the invention has been completed.

[0007] The present invention has been made based on such findings and is as follows. <1> 〔A〕Lubricating base oil, 〔B〕Inorganic powder, 〔C〕Polymer, 〔D〕Fibrous material A tail seal composition for a shield tunneling machine containing The tail seal composition, wherein the weight average molecular weight of the polymer is 35,000 to 400,000. <2> The tail seal composition according to <1>, wherein the degree of non-mixing is 220 to 250. <3> The tail seal composition according to <1> or <2>, wherein the weight average molecular weight of the polymer is 75,000 to 400,000. <4> 〔A〕The lubricating base oil is 10% by mass to 60% by mass based on the total amount of the composition. 〔B〕The inorganic powder is 30% by mass to 70% by mass based on the total amount of the composition. 〔C〕The polymer is 0.5% by mass to 10% by mass based on the total amount of the composition. 〔D〕The fibrous material is 2% by mass to 10% by mass based on the total amount of the composition. The tail seal composition according to any one of <1> to <3>, comprising: <5> A shield tunneling method using the shield tunneling machine tail seal composition according to any one of <1> to <4> in a shield tunneling machine.

Advantages of the Invention

[0008] According to the tail seal composition of the present invention, good water-stopping performance can be maintained for a long time.

Modes for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described in detail with reference to its preferred embodiments. In this specification, unless otherwise specified, the notation "X to Y" for numerical values X and Y means "X or more and Y or less". In such notation, when only the numerical value Y is provided with a unit, the unit is also applied to the numerical value X.

[0010] 〔A〕Lubricating base oil As the lubricating oil base oil used in the tail seal composition of the present invention, the lubricating oil base oil used in ordinary lubricating oils can be used. Among them, mineral oil-based, synthetic, or a mixture thereof is preferable, and mineral oil is more preferable. Examples of lubricating oil base oils other than mineral oil-based or synthetic ones include silicone oil, fatty acid esters, fluorinated oils, alkylnaphthalenes, and animal and vegetable oil-based lubricating oil base oils. The lubricating oil base oil used in the tail seal composition of the present invention preferably has a kinematic viscosity at 40°C of 100 mm 2 / s or more, more preferably 300 mm 2 / s or more, and preferably 3,000 mm 2 / s or less, more preferably 1,000 mm 2 / s or less. In the present invention, the kinematic viscosity at 40°C means the kinematic viscosity at 40°C measured in accordance with JIS K 2283-2000. Also, the lubricating oil base oil used in the tail seal composition of the present invention preferably has a density at 15°C of 0.75 g / cm 3 or more, and preferably 0.98 g / cm 3 or less. In the present invention, the density at 15°C means the density at 15°C measured in accordance with JIS K 2249-1-2011.

[0011] Examples of mineral oils include distillates obtained by atmospheric distillation of crude oil, or distillates obtained by further vacuum distillation of this distillate, which are lubricating oil fractions refined by various refining processes. As the refining processes, hydrorefining, solvent extraction, solvent dewaxing, hydrodewaxing, sulfuric acid washing, clay treatment, etc. can be appropriately combined. By treating these refining processes in an appropriate order in combination, a lubricating oil base oil that can be used in the present invention can be obtained. A mixture of a plurality of refined oils having different properties obtained by subjecting different crude oils or distillates to different combinations of refining processes can also be used.

[0012] As the synthetic base oil, a base material excellent in hydrolysis stability can be used. Examples of such base materials excellent in hydrolysis stability include polyolefins such as poly-α-olefin, polyester, polyalkylene glycol, alkylbenzene, alkylnaphthalene, and GTL base oil. Among the synthetic base oils, poly-α-olefin is preferable in terms of availability, cost, viscosity characteristics, and compatibility with oxidation stability.

[0013] In the tail seal composition of the present invention, the content of the lubricating base oil is preferably 10% by mass or more, more preferably 15% by mass or more, based on the total amount of the tail seal composition. Also, it is preferably 60% by mass or less, more preferably 50% by mass or less. Further, as a specific range, 10% by mass to 60% by mass is preferable, and 15% by mass to 50% by mass is more preferable. When the content of the lubricating base oil is within the above range, a tail seal composition having a desired consistency can be easily prepared.

[0014] 〔B〕Inorganic powder As the inorganic powder used in the tail seal composition of the present invention, powders such as oxides, hydroxides, carbonates, or sulfates of silicon, aluminum, magnesium, or calcium can be used. Mixtures thereof, and powders of ores mainly composed of these naturally occurring compounds can also be used. Specifically, talc, calcium carbonate, magnesium carbonate, calcium sulfate, aluminum hydroxide, magnesium oxide, calcium oxide, aluminum oxide, silica, bentonite, and diatomaceous earth can be used, but it is preferable to use talc. These inorganic powders may be used alone or in combination of a plurality of types.

[0015] The above inorganic powder preferably has an average particle size of 0.5 μm or more, more preferably 5 μm or more. Also, it is preferably 500 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less. As a specific range, those having an average particle size of 0.5 μm to 500 μm are preferable, and 5 μm to 20 μm are more preferable. In the tail seal composition of the present invention, the content of the inorganic powder is preferably 30% by mass or more, more preferably 35% by mass or more, and still more preferably 40% by mass or more, based on the total amount of the tail seal composition. Further, it is preferably 70% by mass or less, more preferably 65% by mass or less, and still more preferably 60% by mass or less. Further, as a specific range, 30% by mass to 70% by mass is preferable, 35% by mass to 65% by mass is more preferable, and 40% by mass to 60% by mass is still more preferable.

[0016] 〔C〕Polymer As the polymer used in the tail seal composition of the present invention, as long as the weight average molecular weight is 35,000 to 400,000, those used in the field of tail seal compositions can be used without limitation. In the present specification, the "polymer" means a compound formed by polymerizing a plurality of monomers. Examples of the polymer include, but are not limited to, an ethylene-propylene copolymer (EPC), an olefin copolymer (OCP), polyisobutylene (PIB), poly(meth)acrylate (PMA), polybutene (PB), a styrene-diene copolymer (SDC), etc. having a weight average molecular weight of 35,000 to 400,000.

[0017] The weight average molecular weight of the polymer used in the tail seal composition of the present invention is 35,000 to 400,000, preferably 50,000 or more, more preferably 75,000 or more, still more preferably 90,000 or more, and particularly preferably 100,000 or more. Further, it is preferably 350,000 or less, more preferably 300,000 or less. As a specific range, 50,000 to 350,000 is preferable, 75,000 to 350,000 is more preferable, 90,000 to 300,000 is still more preferable, and 100,000 to 300,000 is particularly preferable. By the weight average molecular weight being at least the above lower limit value, the water-stopping property can be maintained for a long time. By the weight average molecular weight being at most the above upper limit value, an increase in the viscosity of the tail seal composition is suppressed, and the pumpability is improved.

[0018] In this specification, the weight-average molecular weight of the polymer means the value obtained by gel permeation chromatography (GPC) (the molecular weight obtained by polystyrene conversion). The measurement conditions for obtaining Mw, Mn, and Mw / Mn by GPC are as follows. A person skilled in the art can adopt an appropriate method among Condition 1 and Condition 2 according to the type and weight-average molecular weight of the polymer to be measured, as well as the composition of the tail seal composition, etc. Although not limited to the following, in principle, high molecular weight polymers are measured under Condition 1, and low molecular weight (for example, weight-average molecular weight of 10,000 or less) polymers are measured under Condition 2.

[0019] [GPC Measurement Condition 1] Apparatus: ACQUITY (registered trademark) APC UV RI system manufactured by Waters Corporation Columns: In order from the upstream side, two ACQUITY (registered trademark) APC XT900A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation and one ACQUITY (registered trademark) APC XT200A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation are connected in series Column temperature: 40 °C Sample solution: Tetrahydrofuran solution with a sample concentration of 1.0 mass% Flow rate: 0.8 mL / min Detector: Differential refractive index detector Reference substance: 8 points of standard polystyrene (Agilent EasiCal (registered trademark) PS-1 manufactured by Agilent Technologies) (molecular weights: 2698000, 660500, 325600, 128600, 69650, 30230, 9960, 2980)

[0020] [GPC Measurement Condition 2] Apparatus: ACQUITY (registered trademark) APC UV RI system manufactured by Waters Corporation Columns: In order from the upstream side, one ACQUITY® APC XT125A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation, and two ACQUITY® APC XT45A (gel particle size 1.7 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation are connected in series. Column temperature: 40 °C Sample solution: A tetrahydrofuran solution with a sample concentration of 1.0 mass%. Flow rate: 0.7 mL / min Detector: Differential refractive index detector Reference substance: Ten points of standard polystyrene (Agilent EasiCal® PS-1 manufactured by Agilent Technologies) (molecular weights: 30230, 9960, 2980, 890, 786, 682, 578, 474, 370, 266).

[0021] In the tail seal composition of the present invention, the content of the polymer is preferably 0.5 mass% or more, more preferably 1 mass% or more, and even more preferably 2 mass% or more, based on the total amount of the tail seal composition. Also, it is preferably 10 mass% or less, more preferably 8 mass% or less, and even more preferably 5 mass% or less. Further, as a specific range, 0.5 mass% to 10 mass% is preferable, 1 mass% to 8 mass% is more preferable, and 2 mass% to 5 mass% is even more preferable. In the tail seal composition of the present invention, the content of the polymer is preferably an amount such that the immiscibility degree of the tail seal composition of the present invention is 150 to 350, more preferably an amount such that it is 200 to 300, and even more preferably an amount such that it is 220 to 250.

[0022] The weight average molecular weight and content of the polymer affect the consistency of the tail seal composition. For example, when adding a polymer with a large weight average molecular weight, the consistency of the tail seal composition becomes greater than when adding a polymer with a small weight average molecular weight. Therefore, in order to obtain the desired consistency in the tail seal composition, it is preferable to appropriately adjust the weight average molecular weight and content of the polymer. From the perspective of the solubility of the polymer, a polymer with a large weight average molecular weight is preferably dissolved in a diluent oil in advance and then added to the lubricating base oil. A commercially available polymer product dissolved in a small amount of diluent oil may also be used. The type of diluent oil used here may be one preferably used as the lubricating base oil.

[0023] (Ratio of lubricating base oil to polymer) The tail seal composition of the present invention preferably contains the lubricating base oil and the polymer in a mass ratio of 50:1 to 1:1. By setting this mass ratio, the pumpability and water-stopping property can be further improved. The content ratio of the lubricating base oil to the polymer is more preferably 30:1 to 3:1, and even more preferably 20:1 to 5:1.

[0024] 〔D〕Fibrous The fibrous material is used to form a water-stopping filter cloth layer together with other components by entangling with a wire mesh or a brush made of bundled metal wires in the tail seal part of the shield tunneling machine. In the tail seal composition of the present invention, either natural fibers derived from nature or synthetic fibers synthesized organically can be used. For example, natural fibers include cellulose, cotton fibers, and wool fibers. Synthetic fibers include polypropylene and polyester. Inorganic fibers such as carbon fibers and glass fibers can also be used. The tail seal composition of the present invention preferably contains both natural fibers and synthetic fibers. The mass ratio of natural fibers to synthetic fibers is preferably 1:4 to 4:1, and more preferably 1:2 to 2:1. The average thickness (diameter) of natural fibers and synthetic fibers is preferably 5 μm to 100 μm.

[0025] In the tail seal composition of the present invention, the fiber content is preferably 2% by mass or more, more preferably 3% by mass or more, based on the total amount of the tail seal composition. Further, it is preferably 10% by mass or less, more preferably 5% by mass or less. Further, as a specific range, 2% by mass to 10% by mass is preferable, and 3% by mass to 5% by mass is more preferable. By setting the fiber content within the above range, the water stoppage property and the pumpability can be improved more balancedly.

[0026] (Other additives) In addition to the above components, in the tail seal composition of the present invention, if necessary, detergents, dispersants, anti-wear agents, antioxidants, rust inhibitors, corrosion inhibitors, etc., which are generally used in lubricating oils and greases, can be appropriately added. In particular, as a rust inhibitor, it is preferable to add 0.2 to 2% by mass of fatty acid polyol ester or the like based on the total amount of the tail seal composition.

[0027] (Tail seal composition for shield tunneling machine) The immiscibility degree of the tail seal composition of the present invention is preferably 150 to 350, more preferably 200 to 300, and even more preferably 220 to 250. The measurement of the immiscibility degree in the present invention is carried out by a method conforming to JIS K2220:2013. The tail seal composition of the present invention preferably contains substantially no water. Containing substantially no water means that unavoidably mixed water is allowed. As the water content, it is preferably 5% by mass or less, more preferably 1% by mass or less, based on the total amount of the tail seal composition.

[0028] The tail seal composition of the present invention can be used for the tail seal part between a shield tunneling machine and a segment when excavating tunnels such as road tunnels, railway tunnels, waterway tunnels, and conduit / pipeline tunnels underground. The tail seal composition of the present invention can preferably be used in an environment where it is necessary to continuously apply pressure to the tail seal part between the shield tunneling machine and the segment for a long time.

Examples

[0029] The present invention will be described below using examples. The present invention is not limited to the following embodiments. Unless otherwise specified, % indicates mass %.

[0030] <Formulation of Tail Seal Composition> For each example and each comparative example, a test tail seal composition was prepared by blending a lubricating base oil, an inorganic powder, a polymer, and a fibrous material at the blending ratios shown in Table 1 (based on the total amount of the tail seal composition). The obtained tail seal composition was evaluated for water stoppage performance. The evaluation results are shown in Table 1.

[0031] Base oil A1: Mineral oil (manufactured by ENEOS, solvent-refined lubricating base oil, density at 15°C; 0.90 g / cm 3 , kinematic viscosity at 40°C; 522 mm 2 / s) Inorganic powder B1: Talc, average particle size; 12 μm Polymer C1: Polyisobutylene (PIB); weight average molecular weight 36,000 Polymer C2: Ethylene-propylene copolymer (EPC); weight average molecular weight 297,000 Polymer C3: Ethylene-propylene copolymer (EPC); weight average molecular weight 144,000 Polymer C4: Polybutene (PB); weight average molecular weight 1,800 Polymer C5: Polymethacrylate (PMA); weight average molecular weight 33,400 Fibrous material D1: Synthetic polyester fiber (average length; 5 mm, average diameter; 80 μm) Fibrous material D2: Cotton (average length; 5 mm, average diameter; 20 μm) The weight average molecular weights of the above polymers C1 to C3, C5 were measured under the aforementioned "GPC measurement conditions 1", and C4 was measured under the aforementioned "GPC measurement conditions 2".

[0032] <Evaluation of Water Stoppage Performance> The water stoppage performance was evaluated by the following procedure. A stainless steel pressure vessel with an inner diameter of 52 mm having a total of 16 openings (diameter 3 mm) arranged in 4 rows vertically and horizontally with a center-to-center spacing of 5 mm was used at the central part of the bottom. A stainless steel mesh (40 mesh) was placed on the openings, and the tail seal composition prepared above was filled so that the grease thickness became 40 mm. The pressure vessel filled with the tail seal composition was connected to a hydraulic pump, hydraulic pressure was applied to the tail seal composition, and the water tightness was evaluated based on the presence or absence of water outflow from the bottom opening. Also, in this test, when hydraulic pressure was applied, oil or polymer etc. leaked from the grease container, so the pressure decreased. Therefore, the pressure was increased to 3.5 MPa at determined time intervals according to the procedures (1) to (7) shown below.

[0033] (1) From the start of the test for 3 minutes, operate the pump so that it becomes 3.5 MPa. (2) Observe the state as it is from 3 minutes after to 10 minutes after. (3) From 10 minutes after to 30 minutes after, adjust to 3.5 MPa every 10 minutes. (4) From 30 minutes after to 180 minutes after, adjust to 3.5 MPa every 30 minutes. (5) From 180 minutes after to 600 minutes after, adjust to 3.5 MPa every hour. (6) After 600 minutes, since it becomes night time, leave it until 24 hours have passed. (7) After 24 hours have passed, confirm the presence or absence of water outflow from the bottom opening.

[0034] <Measurement of consistency> Based on the method conforming to JIS K2220:2013, the immiscible consistency of each tail seal composition was measured.

Table 1

[0035] For the tail seal compositions of Examples 1 to 3, no water leakage was observed even after 24 hours had passed since the start of the test. In Comparative Example 1 where a polymer having a weight average molecular weight of 1,800 was added, water leakage occurred about 3 to 4 hours after the start of the test. In Comparative Example 2 where a polymer having a weight average molecular weight of 33,400 was added, water leakage occurred about 90 minutes after the start of the test.

Industrial Applicability

[0036] According to the tail seal composition of the present invention, good water-stopping property can be maintained for a long time.

Claims

1. 〔A〕a lubricating base oil in an amount of 10% to 60% by mass based on the total amount of the composition, and 〔B〕an inorganic powder in an amount of 30% to 70% by mass based on the total amount of the composition, and 〔C〕at least one polymer selected from the group consisting of ethylene-propylene copolymer (EPC), olefin copolymer (OCP), polyisobutylene (PIB), poly(meth)acrylate (PMA), polybutene (PB), and styrene-diene copolymer (SDC) in an amount of 0.5% to 10% by mass based on the total amount of the composition, and 〔D〕a fibrous material in an amount of 2% to 10% by mass based on the total amount of the composition, a tail seal composition for a shield tunneling machine, comprising: The tail seal composition, wherein the weight average molecular weight of the polymer is 35,000 to 400,000.

2. The tail seal composition according to claim 1, having an immiscibility consistency of 220 to 250.

3. The tail seal composition according to claim 1 or 2, wherein the weight average molecular weight of the polymer is 75,000 to 400,000.

4. A shield tunneling method using the tail seal composition for a shield tunneling machine according to any one of claims 1 to 3 in a shield tunneling machine.

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