JP3193572B2 - Cathodic protection method for the outer surface of an existing iron tunnel and its electrode device for cathodic protection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic protection method for an outer surface of an existing steel or cast iron or other iron tunnel and an electrode apparatus for the protection, and more particularly to a hollow electrode for injecting a backfill material (filler). The present invention relates to an anticorrosion method using an electrode material connected to an electrode mounting bracket and an electrode apparatus for the anticorrosion.

[0002]

2. Description of the Related Art Conventionally, in a lining work of an iron tunnel, a grout material such as concrete is filled between a tunnel hole and an iron shield segment to form a grout portion. Fibers are often mixed into the grout material for the purpose of improving strength.

[0003] Since the lining portion is a portion that is difficult to visually confirm, it is difficult to find even if a gap is generated. Recent developments in acoustic analysis techniques have largely resolved this type of problem, but tunnels constructed several years ago have been incompletely filled with grout. In addition, the steel shield segment and grout are likely to peel off at the interface due to the vibrations caused by passing a car or train, and once peeled off, the peeling spreads over a large area of the iron tunnel. Underground water penetrates into the gap between the peeled portions, but in this early stage, the surface of the iron shield segment is passivated by the alkali component of the concrete, and no corrosion occurs.
However, over time, the concrete neutralizes, the passivation of the surface of the iron shield segment is no longer maintained, and corrosion begins to occur. In particular, in recent years, groundwater contaminated by sludge and sediment and groundwater with low specific resistance have been observed underground in freshly buried and coastal areas, and corrosion of the outer surface of the iron shield segment in this area has become a serious problem.

[0004] Anticorrosion measures on the outer surface of the iron shield segment have hardly been studied so far. This is the case when the secondary lining with concrete is performed next to the primary lining with the iron shield segment, or when the soil improving agent is injected into the outer periphery of the shield segment and the grout material is filled, the corrosive water comes into contact with the iron material directly. It has been considered not to be. However, there are many cases in which groundwater containing rust juice is seeping out between segments, and as described above, the groundwater often has a water quality that promotes corrosion.

[0005] Even in the case of secondary work, if a penetration hole is formed in the skin plate due to corrosion of the iron segment, groundwater intrudes therefrom, and the corrosion inside the iron segment proceeds rapidly. As a result, volume expansion due to rust occurs, and cracking or falling off of the secondary crawler occurs within a relatively short time after the generation of the through-hole.

[0006] The corrosion of the outer surface of the iron tunnel cannot be observed without removing the actual one, and the degree of corrosion cannot be accurately grasped because the corrosion greatly changes due to a slight environmental difference. However, it is considered that the fact that the iron surface is exposed to the above-described environment clearly causes corrosion, which is gradually progressing.

[0007] Iron tunnels are socially extremely important facilities such as subways and electric power cooperative ditches. Once an anomaly occurs in a tunnel, repairing or reconstructing the tunnel is a major sacrifice that cannot be achieved by mere construction alone. Will be accompanied. Therefore,
Anticorrosion measures for these facilities are extremely important.

Conventionally, as an anti-corrosion technique for this part, an electric anti-corrosion method using an external power supply system is generally used. The external corrosion protection method using an external power supply system is a system in which one insoluble electrode material is buried in the soil at a position away from the body to be protected and supplies a corrosion protection current. In this system, however, only one electrode material is used. A wide range of corrosion-protected bodies will be protected. Normally, an iron tunnel is insulated at various points, and particularly in a tunnel constituted by shield segments, the segments are often insulated by corrosion of segment fastening bolts. For this reason, in the case where the external power supply system is used for electrolytic protection, if the part to be protected has an insulating part, the insulating part causes a large corrosion due to a jumping phenomenon.
Also, in urban areas, there are various underground structures other than the corrosion-protected bodies, and there is a problem that these cause corrosion due to interference. In addition, since iron tunnels have a large area to be protected against corrosion, appropriate arrangement of electrode materials is required to protect the entire area.However, since iron tunnels are usually located in urban areas, such arrangements are virtually impossible. Become.

Reinjection of mortar or painting can be considered as a method of preventing corrosion of this portion other than the external power supply system. However, in the former case, in the case of existing structures, there is no method to confirm whether the mortar has been able to fill the outer periphery of the tunnel. Peels off and cannot stop corrosion. The latter cannot be carried out without removing all the soil around Tonenur, so the cost is very high and the place where construction is possible is very limited.
The conventional techniques for preventing corrosion of the outer periphery of an iron tunnel have the above-mentioned disadvantages.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and makes it possible to efficiently prevent corrosion of the outer periphery of an iron tunnel without stopping the function of the tunnel. It is an object of the present invention to provide a cathodic protection method and a cathodic protection electrode device.

[0011]

In order to achieve this object, the present invention employs an electrolytic protection method having the following structure.

That is, according to the method of the present invention for protecting the outer surface of an existing iron tunnel from corrosion, after investigating an environmental condition in contact with the outer surface of the existing iron tunnel, a hole is formed in the wall surface and the soil of the tunnel, and a reinforcing iron plate having an electrode through hole is provided. Is welded to the inner surface of the wall, and after fixing a cylindrical electrode mounting bracket having a filler introduction port to which the electrode material is connected to the reinforcing iron plate so that the electrode material protrudes from the outer surface, Inject the filler,
The present invention is characterized in that an anticorrosion current can be supplied from the electrode material to the outer surface of the tunnel by sealing the opening of the electrode mounting bracket.

Hereinafter, the cathodic protection method of the present invention will be described with reference to the drawings. 1a to 1f are process diagrams showing an example of the cathodic protection method of the present invention.

In the present invention, first, the environment in contact with the outer surface of the existing iron tunnel is investigated. Thereafter, as shown in FIG. 1A, the tunnel wall surface, that is, the iron segment 1 is blown off by a fusing jig 3. Next, as shown in FIG.
The grout layer 2 outside the iron segment 1 is pierced by a piercing jig 4.

Next, as shown in FIG.
The reinforcing iron plate 5 which is hollow and threaded at that portion is welded to the melted portion. Then, as shown in FIG.
The electrode mounting bracket 19 to which the electrode material 6 is connected is inserted into the hollow part, and is fixed with the threaded portion of the reinforcing iron plate 5.

Further, as shown in FIG. 1E, the adapter 7 for injecting the backfill material is attached to the electrode mounting bracket 19,
The backfill material 8 is injected into the void portion of the grout layer 2. Finally, as shown in FIG. 1f, after filling the gap between the electrode material 6 and the grout layer 2 with the backfill material 8, a plug 9 is inserted into the inlet.
And connect the conducting wires.

Next, an electrode device used in the present method will be described with reference to the drawings. FIG. 2 is a diagram showing an attached state of the electrode device attached to the iron segment 1 inside the segment. A reinforcing iron plate 5 is attached inside the iron segment 1 and a plug 9 is provided at a backfill material introduction port. Have been.

FIGS. 3 to 6 are cross-sectional views taken along the line AA 'of FIG. 2, and show the mounting state of various electrode devices on the outside of the segment.

In FIG. 3, a reinforcing iron plate 5 having a threaded electrode through hole is welded to the iron segment 1.
A soluble electrode material 6 having a hollow core 10, for example, a magnesium alloy anode is penetrated and screwed into the threaded hole. After injecting a backfill material (for example, a mixture of 30% by weight of bentonite, 30% by weight of gypsum, and 10% by weight of sodium sulfate mixed with 20% by weight of tap water) from the core metal 10 through the backfill material inlet 11 A plug 9 is plugged into the inner inlet of the cored bar 10, and the cored bar 10 and the reinforcing iron plate 5 are electrically connected by a conductive line 12. In addition, 13 and 14 are an epoxy resin and a rubber packing, respectively.

FIG. 4 differs from FIG. 3 in that
It is characterized in that the core is a combination of a rod-shaped core 10 ′ and a cylindrical electrode mounting bracket 19. Accordingly, since the backfill material is injected from the backfill material injection port 18 provided on the side surface of the mounting bracket 19, the weight of the electrode material can be increased, and a long life can be achieved. Further, in the case of the structure of the present apparatus, an external electrode system using an insoluble electrode material can be used, so that the life of the electrode material can be further extended. Examples of the insoluble electrode material include magnetic iron oxide, silicon cast iron, and platinum-plated titanium wire. In the figure, reference numeral 15 denotes an electric wire.

FIGS. 5 and 6 show a backfill bag 17 attached to the electrode device of FIGS. 3 and 4 by means of a backfill bag fixture 16.

For example, in FIG.
After the tapping thread is provided inside one end of the electrode material 6, the electrode material 6 is formed at a constant thickness outside the hollow core bar 10 except for one end portion. Next, a cylindrical mounting member 19 having an outer diameter threaded concentrically is provided outside one end of the hollow cored bar 10.
A backfill material inlet 11 is provided at one end of the hollow cored bar 10.
However, a backfill material inlet 18 is provided at the other end. A backfill material bag 17 is fixed at the root of the electrode portion so that the backfill material 8 extends over the entire circumference of the electrode material 6, and the backfill material is filled after installation at the site. I have.

[0023]

According to the method of the present invention, the electrode material serving as the anode is directly attached to the body to be protected in the anticorrosion method of the existing iron tunnel, and one electrode material protects a limited area. This is a method that does not cause interference with other buried objects and corrosion due to jumping phenomena, which has been a problem with this type of method in the past.

This is achieved by calculating an anticorrosion current reaching range by environmental surveys such as investigating the shape of the iron tunnel, the filling state of the grout layer, and the specific resistance, and installing one electrode material in each range. You. When the electrode material is worn out, the electrode material mounting part is threaded, so it can be easily replaced with a new electrode material, and unlike the conventional underground method or welding method, the replacement work is extremely easy It is.

In the hollow core metal with an inlet used in the present invention, after the electrode material is fixed to the corrosion-protected body by screwing, the hollow portion of the hollow core metal is used for the grout material or the backfill material. Used for injection. Thereby, for example, when a flowing water layer is not formed on the outer surface of the body to be protected, a backfill material is injected to eliminate voids existing in the electrode material surface and the grout layer, and as a result, low ground resistance of the electrode material is reduced. An effective anticorrosion effect is exhibited. If there is a flowing water layer, grout material such as quick-setting mortar is injected.

When there is a possibility that the backfill material is injected in a large amount, the backfill material can be made unnecessary by using an electrode material with a bag for the backfill material as shown in FIGS. Do not allow injection. The amount of the backfill material to be injected and the size of the bag for the backfill material are determined based on the investigation of the state of the grout layer, the state of the void, and the like.

Although the mounting method using screws has been described above, another simple mounting method, for example, a method of providing a flange portion and fixing with a bolt or the like may be used.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

EXAMPLE An example of an actual iron segment will be described. The segment targeted for the test was a ductile segment made of FCD450, which has been in use for more than 20 years.

Although the outside of the segment is filled with a mortar grout material by design by 500 mm, slight water leakage is observed from the gap between the segments, and corrosion of the outer wall of the segment is concerned.

In the test, first, the state of the grout layer and the state of the voids were investigated by analyzing the percussion and percussion waves. Next, a hole having a diameter of 10 mm was formed at a position where the electrode material was to be mounted, and the state of water leakage was investigated. After confirming that there was almost no water leakage, a 70 mmφ hole was made in the segment.

In the following, construction was carried out in accordance with the above-described procedures shown in FIGS. The length of the electrode part was 300 mm. 500 mm from the center of the electrode material, 1000 to determine the effect
mm, 1500 mm, and 2000 mm, a saturated calomel electrode was embedded. At the time of embedding, a gel electrolyte in which 10% of carboxymethylcellulose was dissolved in an aqueous solution of 5% of sodium chloride was filled in the hole of the calomel electrode insertion portion, and then the electrode was inserted. FIG. 7 shows the measurement results.

As is clear from the results of FIG. 7, according to the potential change, although the degree of polarization decreases as the distance from the electrode material increases, the polarization advances at any position of the electrode material. It was confirmed that anticorrosion was achieved.

[0034]

As described above, according to the present invention, the electrode material for cathodic protection can be attached to the shield segment of the existing iron tunnel without stopping the function of the tunnel, and the anticorrosion state can be confirmed by measuring the potential. If the electrode material is worn out, the electrode material can be easily renewed, and once it collapses, repair work is extremely difficult.However, it is difficult to visually recognize the shield segment outer wall in an existing steel tunnel which is a very important facility in society. There is an effect that corrosion damage can be protected for a long time.

In addition, since the electrode is fixed by a screw method, replacement of the electrode material when the electrode material is exhausted is compared with the conventional method of burying the electrode material in soil or welding method which has been generally used in the cathodic protection method. It becomes very easy. This is effective for the maintenance of facilities such as railway tunnels where the working time is limited.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of the cathodic protection method of the present invention.

FIG. 2 is a diagram showing an electrode device attached to an iron segment, showing a state of attachment inside the segment;

FIG. 3 is a sectional view showing a first example of the electrode device of the present invention.

FIG. 4 is a sectional view showing a second example of the electrode device of the present invention.

FIG. 5 is a sectional view showing a third example of the electrode device of the present invention.

FIG. 6 is a sectional view showing a fourth example of the electrode device of the present invention.

FIG. 7 is a graph showing a change over time in potential.

[Explanation of symbols]

1: Iron segment, 2: Grout layer, 3: Fusing jig,
4: punching jig, 5: reinforcing iron plate, 6: electrode material, 7: adapter, 8: backfill material, 9: stopper, 10: hollow cored bar,
11: Backfill material inlet, 12: Conductive wire, 13: Resin, 14: Rubber packing, 15: Electric wire, 16: Backfill material bag fixture, 17: Backfill material bag, 18:
Backfill material inlet, 19: electrode mounting bracket.

Continuation of the front page (56) References JP-A-2-209494 (JP, A) JP-A-2-43384 (JP, A) JP-A 4-113000 (JP, U) JP-A 55-13908 (JP) , U) JP 48-36811 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23F 13/00-13/22 E21F 17/00 JICST file (JOIS) (tunnel , Anti-corrosion) WPI (DIALOG) (tunnel, corrosion, electode)

Claims (5)

(57) [Claims] After investigating an environmental condition in contact with the outer surface of an existing iron tunnel, holes are drilled in the wall surface and soil of the tunnel, and a reinforcing iron plate having an electrode through hole is welded to the inner surface of the wall,
After fixing a cylindrical electrode mounting bracket having a filler introduction port to which the electrode material is connected to the reinforcing iron plate so that the electrode material protrudes to the outer surface, the filler is fed from the filler introduction port, and An electrolytic protection method for an outer surface of an existing iron tunnel, wherein an anticorrosion current can be supplied from an electrode material to an outer surface of the tunnel by sealing an opening of an electrode mounting bracket. 2. A reinforcing iron plate having an electrode through hole welded to the inner surface of an existing iron tunnel, a cylindrical electrode mounting member attached to the iron plate, a hollow core connected to the metal member, and the core. An electrode device for cathodic protection comprising an electrode material formed outside gold. 3. A reinforcing iron plate having an electrode through-hole welded to the inner surface of an existing iron tunnel, attached to the iron plate,
An electrode device for cathodic protection comprising a cylindrical electrode mounting bracket having a filler inlet on a side surface thereof, a metal core connected to the metal fitting, and an electrode material formed outside the metal core. 4. A reinforcing iron plate having an electrode through hole welded to the inner surface of an existing iron tunnel, a hollow core penetrating through the iron plate, and an electrode mounting fitting concentrically fitted to an end of the core bar. And an electrode material formed outside the cored bar. 5. The electrode device according to claim 2, further comprising a filler bag provided so as to cover the entire circumference of the electrode material.