JPH03212600A - Segment provided with corrosionproof layer - Google Patents

Abstract

PURPOSE:To prevent sheets from peeling from a segment and secure watertightness so as to restrain corrosion of primary covering and enhance durability by stacking sheets of synthetic rubber and sticky rubber asphalt, and providing on the surface of the segment a corrosionproof layer whose side faces are hanged down by more than a predetermined amount. CONSTITUTION:Sticky rubber asphalt 3 is formed into a sticky layer. Vulcanized EPDM sheets 1 of a synthetic rubber withstanding the use of tail grease and whose coefficient of friction may be 0.13 or so against sliding of a sealed tail are stacked on the sticky layer via polyorefine films 2 to form a corrosionproof sheet A. The corrosionproof sheet A is stuck to a segment B via a primer 5 while the right and left side faces thereof A2, A3 are each hanged down by more than 50mm. Invasion of sea water etc., is prevented so as to prevent corrosion of reinforcements while preventing the sheet from being peeled from the segment by peeling stress caused by sliding of the sealed tail during assembly of the segment.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to corrosion protection of segments for assembling shield tunnels.

[Conventional technology]

The segments that make up the primary lining of the shield tunnel are made of concrete with reinforcing bars placed near the surface, so they are water permeable, and if they come in contact with seawater for a long period of time, the reinforcing bars will rust, causing concrete IJ-FC cracks. Therefore, in order to improve durability, it is customary to apply epoxy resin to the surface of the segment to prevent corrosion, or to use resin concrete. It is difficult to maintain durability without being able to prevent corrosion.

[Problem that the invention seeks to solve]

If the diameter of the shield tunnel is large and the installation location is on the seabed or deep underground, segments that are exposed to high water pressure will cause rusting of the reinforcing steel due to seepage water and deteriorate the concrete IJ, so the durability of the primary lining should be reduced. In addition to being significantly shortened, there is also the disadvantage that when assembling the segments, the shield tail slides directly on the concrete surface, causing wear on the plush of the shield tail.

In order to eliminate the above defects, an anti-corrosion layer is provided on the surface of the segment, and this anti-corrosion layer has strong resistance to high water pressure and thickening, and deteriorates due to the tail grease injected when the shield tail is slid when assembling the segment. The aim is to develop a segment with an anti-corrosion layer that can ensure durability by preventing the ends of the anti-corrosion layer from peeling off due to peeling stress caused by friction, abrasion, or sliding.

[Means to solve the problem]

When assembling segments, in places where the circulating mud pressure is about 10 atm and the seawater pressure is 6 atm, the corrosion protection layer will be damaged if air bubbles are present at the interface between the anticorrosion layer and the segment. To prevent this, watertight adhesive is used. In order to eliminate air bubbles from the interface, the adhesive layer is made of com asphalt, which has the adhesive force of Van der Waals molecular force, and has high compression resistance, less deterioration due to shield tail Chris F, and a shield. Friction coefficient due to tail sliding (Powden friction coefficient surface pressure approximately 10 to 9/cm" at
(20℃, using stainless steel wire) Vulcanized synthetic rubber B that can withstand tail grease of about 0.13
In order to use a PDM (same name for ethylene, fluoropylene, and diene monomer polymer) sheet as the front surface, it is possible to laminate a rubber asphalt sheet and an EPDM sheet by welding a polyolefin film to the back side and provide a corrosion-protective layer for the segment. done. When assembling the segments, the shield tail slides on the surface, so if there is an anti-corrosion layer only on the surface of the segment, the peeling stress will be concentrated on the edges, so there is a high possibility that it will peel off from the terminal, so let the terminal hang down on the side. In order to avoid peeling, it is necessary to adjust the length of the lower side of the hanging part and the length of the upper side, since wrinkles will usually occur in the adhesive part unless the lower side of the hanging part shrinks due to the curvature l of the segment surface. It was determined that a laminated material made of flexible rubber asphalt and a synthetic rubber sheet would be suitable for adhesion, since the differences would be absorbed by shrinkage and wrinkles would be avoided.

[Effect]

This will be explained in detail by giving examples.

The shape of the segment is H'' multi-0Φ, in which the primary lining of a shield tunnel is constructed by assembling several concrete segments with reinforcing bars with a radius of curvature of 5 m or more, but here, the radius of curvature is 7 m, Width 1, 5
A case will be described in which a ring is composed of 12 rings having a thickness of 0.65 m and a thickness of 0.65 m.

The upper layer of the anticorrosion layer is an EPDM sheet (JISA-6008 standard product) with a thickness of 1H, a width of 1.7m, and a length of about 4m, and is highly elastic and has high compression resistance so that the shield tail slides on the surface during assembly. Inject tail plush (e.g. stainless steel wire bundle) and tail grease to increase circulating mud water pressure IQk.
g/cm" to stop water from leaking and have a friction coefficient of 0.
11 to 0.14, so there is no damage.In order to prevent the migration of low molecular weight rubber asphalt, a 30μ polyolefin film welded to the back of the EPDM sheet is suitable.

The lower layer is rubber asphalt and 8BS (styrene).

This asphalt is a mixture of 12% to 15% of butadiene copolymer). Excellent waterproofness, tensile strength is 6
kg/cI! L” or more, tensile elongation rate 1,000
% or higher and at a temperature of 15°C or higher, Conc I has good self-leveling ability, a smooth finished surface, and low air permeability.
When it is attached to the J-to surface, the air bubbles that exist at the interface are narrowed by the self-leveling ability, and the gaps between the non-adhesive spaces are reduced. Van der Waals molecular force acts and the two sides adhere, so the air bubbles become atomized and the rubber asphalt layer is formed. It is observed that the adhesive strength increases with the passage of time, as it is presumed that the adhesive is absorbed between the molecules and disappears.

The strength of this adhesion is determined by the unit adhesion strength x the adhesion area. Van der Waals molecular force, which works to increase the adhesion area, is related to temperature and pressure. It can be seen that the anti-corrosion layer of the segment adhered to the surface of the primary lining has a high adhesion strength and is watertightly bonded.

If there are air bubbles at the interface, 1110g/GK”
When a certain amount of water pressure is applied, air bubbles move and aggregate, causing damage to the anti-corrosion layer.In order to ensure long-term durability, air bubbles at the interface must be eliminated to make the layer completely watertight. When bonded, the water pressure is applied to the surface of the underlying segment through the anti-corrosion layer, so the anti-corrosion layer will not break or otherwise be damaged.

〔Example〕

Figure 1 is a sectional view showing the structure of the anticorrosion sheet (A) of the invention.

(1) is an EPDM sheet, (2) is an EPDM sheet (1
) is a 30μ thick polyolefin film that is explosively bonded to the back side. In (3), adhesive rubber asphalt with a thickness of 1 inch is laminated to form an anticorrosion layer (A), and a release paper (4) is attached to the lower surface of the anticorrosive layer (A) to protect the adhesiveness of the rubber asphalt.

EPDM sheet (1) is a JI8A-6008 standard product.

Com asphalt sheet (3) is 8BS synthetic rubber 12%
The properties of the asphalt mixture are as follows.

Softening point 100±5°C Penetration at 25°C 5o±5 Tensile strength at 200G 8-12 kg/
ctn mushroom tensile elongation rate at20'c 1,200~
The rubber asphalt layer bonded to the 2,000-degree glass surface has air bubbles interposed at the interface that occur during bonding at a temperature of 15°C.
If left to stand for 2 to 14 days, the air bubbles will disappear and the process of complete adhesion can be observed through the glass surface.

The test results of this anti-corrosion sheet are (Test method JISA-60
(According to 09) a, (Tensile test) Test piece No. 3 dumbbell Thickness 2 mm Test temperature 20°C Tensile speed 500 yen/m1n b, (Tear test) Shear peel test Specimen Width 40 os x Length 150 times, 2 sheets overlap 40 x 4 Q m , Temperature 20''C Moisture absorption Immersion temperature 20C Test piece size 20X50IjI Average of 3 pieces (attached) W is the sum of the sheet and water, w indicates water absorption.

Figure 2 is a perspective view of segment (B), and the reinforcing bars are placed at a depth of 20 to 100 I3Il from the surface, so if water floods from the surface, the reinforcing bars are likely to rust.

The shape has a radius of curvature of 7m, a width of 1.5m, and a height of 0.65m.

One ring is formed by assembling 12 segments with a length of 3.66 m. The primary lining is constructed by connecting these rings.

Figure 3 is a cross-sectional view showing the anti-corrosion sheet (A) attached to the segment (B).

A primer (5) prepared by diluting rubber asphalt with a solvent is applied to the portion of the segment (B) where the anticorrosive layer (A) is to be applied to promote adhesion, and then dried.

Anti-corrosion sheet) Peel off the release paper (4) in (A), and since the anti-corrosion sheet is 1.7 m wide and the segment width is 1.5 m, it is pasted seamlessly on the anti-corrosion layer on the surface (A1), and the anti-corrosion layer on the side surface is (front, rear, left and right sides At, As, A4, As)
will be hung down for 100m and pasted. At the four corners, the anti-corrosion sheet is folded and bonded to prevent water leakage, so the segments are cut in advance to adjust the thickness and then bonded.

There are hanging parts (At, Am, A4,
As for As), it is recommended that the segments be cut off in advance during manufacture to compensate for the increased thickness due to overlapping when joining adjacent segments, and that the corners be slightly rounded to avoid concentration of stress.

By hanging down on the sides, the end of the anti-corrosion layer can be prevented from being directly affected by the peeling stress caused by sliding under the pressure of 10 kg/cm'' of circulating mud in the plush of the shield tail, and by the tail grease injected into the plush. Since the coefficient of friction is reduced, there is less wear on the plush and the anti-corrosion layer on the surface can be assembled without damage.When the segments are joined together, water-expandable resin seals are applied all around the sides to ensure waterproofing between the joints. Attach 2 to 4 rows of strips (6).

Alternatively, there is also a method of creating a waterproof layer by touching the surface with an appropriate width of the side surface.

Figure 4 is a cross-sectional view showing a ring of primary lining made up of segments (B) with anti-corrosion layer (A).

For convenience of explanation, a 6-ring ring is shown.

(6) is the water expansion resin seal band, (7) is the joint bolt, and (7t) is the joint bolt hole.

Although we have described EPDM sheets here, butyl rubber, 88R rubber, and chloroprene rubber are used as synthetic rubbers, and in addition to adhesive rubber asphalt, there are also rubber asphalts mixed with unvulcanized butyl rubber, 88R rubber, butadiene rubber, etc. used.

〔Effect of the invention〕

The segments provided with the anti-corrosion layer of the present invention prevent seawater from entering the soil for a long period of time and protect the reinforcing bars from corrosion in the soil at 60 m below the seabed. In addition, when assembling the segments, peeling that occurs due to the shield tail sliding on the surface of the anti-corrosion layer is avoided. There is no concern that it will peel off from the end due to stress, the tail grease will not deteriorate due to the injected tail grease, and the wear of the shield tail plush will be reduced, extending the working life of the shield machine, making the primary lining structure safer. The shield tunnel of this invention, which consists of segments with an anti-corrosion layer, is an economical construction method that ensures durability.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the structure of the anticorrosion sheet (A) of the invention. Figure 2 shows a perspective view of the segment. Figure 3 is a cross-sectional view showing how the anti-corrosion layer (A) is attached to segment l-(B). Figure 4 is a cross-sectional view showing the ring of the primary lining assembled from the segment (B) with anti-corrosion layer (A). A Anti-corrosion sheet (1) EPDM sheet (2) Polyolefin film (3) Rubber asphalt sheet (4) Release paper (5) Primer B Segment (6) Water-swellable resin sealing band C-Next lining ring (7) Segment joint bolt (71) Hole A of the segment joint bolt, Corrosion protection layer A affixed to the surface of the segment, Corrosion protection layer affixed hanging down to the front side of the segment Corrosion protection layer hanging down and affixed to the rear side of the segment Corrosion protection layer hanging and sticking to the left side of the layer segment Corrosion protection layer hanging and sticking to the right side of the segment

Claims (1)

[Claims] In order to suppress corrosion and ensure durability of the primary lining of a shield tunnel where concrete segments with reinforcing bars are assembled, an anti-corrosion layer is provided on the surface of the segment when assembling the segments, and the anti-corrosion layer is removed by sliding of the shield tail. In order to avoid peeling stress acting on the surface and peeling off of the terminals, the pasting finish should be hung down by 50 mm or more from the side to prevent water channels from forming in the anti-corrosion layer at the joint surface even when the segments are joined together, and between the segments and the shield tail. Synthetic rubber sheets and adhesive rubber asphalt sheets are laminated to form an anti-corrosion layer that reduces the coefficient of friction between the
A segment provided with an anti-corrosion layer that does not wrinkle even when hanging down for more than 300 m and is watertightly bonded to the entire surface with a single seamless sheet.