JPH0881792A - Electrolytic protective method for outside surface of existing iron tunnel and electrode device for electrolytic corrosion protection therefor - Google Patents

Abstract

PURPOSE: To obtain efficient electrolytic corrosion protection of the outer peripheral part of an iron tunnel without stopping its function by boring the wall surfaces and the inside of soil in the tunnel with holes, inserting and fixing cylindrical electrode mounting fittings via reinforcing iron plates into these holes and feeding a packing material, thereby hermetically sealing the holes. CONSTITUTION: The environmental condition in contact with the outside surfaces of the existing iron tunnel are investigated and thereafter, the iron segments 1 and grout layers 2 are bored with the holes by using fusion cutting jigs, drilling jigs, etc. The reinforcing iron plates 5 having electrode pass holes are then welded to the inside surfaces of the walls. The cylindrical electrode mounting fittings 19 are inserted from these electrode pass holes and are fixed to the reinforcing iron plates 5. As a result, the electrode materials 6 disposed on the outer side of the hollow mandrels of the fittings 19 are held in the state of projecting the materials to the outside surfaces. Back filter materials 8 are then fed from the packing material introducing ports of the electrode mounting fittings 19 and are thereafter, the apertures are hermetically sealed by plugs 9. As a result, the supply of corrosion protective currents from the electrode materials 6 via the electrode mounting fittings 19 to the outside surfaces of the tunnel is made possible.

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 iron tunnel such as an existing steel, cast iron, etc. and an electrode apparatus for the electrolytic protection, and more particularly to a hollow filler for injecting a backfill material (filler). The present invention relates to a cathodic protection method using an electrode material connected to an electrode fitting and a cathodic electrode device therefor.

[0002]

2. Description of the Related Art Conventionally, in an iron tunnel, in a lining work, 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 in this grout material for the purpose of improving the strength.

Since this lining portion is a portion which is difficult to visually confirm, it is difficult to find even if a void portion is formed. Recent developments in acoustic analysis techniques have largely resolved this type of inconvenience, but tunnels built several years ago have incomplete grout filling. Further, the iron shield segment and the grout part are liable to peel off at the interface due to the vibration caused by the passage of a car or train, and the peeling once generated spreads over a wide area of the iron tunnel. Groundwater infiltrates into the gaps of the peeling part, but at this early stage, the alkaline component of the concrete causes the surface of the iron shield segment to be passivated and corrosion does not occur.
However, over time, the concrete becomes neutral, the passivation of the surface of the iron shield segment is no longer maintained, and corrosion begins to occur. Particularly in recent years, underground water in buried land and coastal areas has been observed to have contaminated groundwater due to sludge and sediments and groundwater with a low specific resistance, and corrosion of the outer surface of the iron shield segment in this area has become a serious problem.

[0004] The anticorrosion measures for the outer surface of the iron shield segment have hardly been studied so far. This is because when corrosive water is directly contacted with the iron material when the primary lining with the iron shield segment is followed by the secondary lining with concrete, the soil modifier is injected into the outer periphery of the shield segment, and the grout material is filled. It has been considered not to do so. However, there are many cases in which groundwater containing rust is seeping out from between the segments, and as mentioned above, most of the groundwater has a water quality that promotes corrosion.

Further, even when secondary shoes are used, if a through hole is formed in the skin plate due to corrosion of the iron segment, groundwater will intrude there from and the corrosion inside the iron segment will rapidly progress. As a result, volume expansion occurs due to rust, and cracks or dropouts of the secondary footwear occur within a considerably short time after the formation of the through holes.

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 it greatly changes due to slight environmental differences. However, it is considered that the exposure of the iron surface to the above-mentioned environment obviously causes corrosion, which is gradually progressing.

[0007] The iron tunnel is a socially very important facility such as a subway and a power cooperative ditch, and once an abnormality occurs in the tunnel, repairing or reconstructing the tunnel is a great sacrifice that cannot be achieved by merely construction. Will be accompanied. Therefore,
Anticorrosion measures for such facilities are extremely important.

Conventionally, as the anticorrosion technique for this portion, an electrocorrosion method using an external power supply system is generally used. This cathodic protection method using an external power supply system is a system in which one insoluble electrode material is embedded in the soil at a position away from the body to be protected and a corrosion protection current is supplied. In this system, one electrode material is used. Corrosion protection of a wide range of corrosion-resistant objects. In general, an iron tunnel is insulated at various places, and particularly in a tunnel including a shield segment, the segments are often insulated by corrosion of the segment fastening bolts. For this reason, in the case where the external power supply method is used for the anticorrosion, if there is an insulating portion in a part of the body to be protected, a jumping phenomenon causes a large corrosion of the insulating portion.
In urban areas, there are various underground structures in addition to the corrosion-preventing objects, and there is a problem in that these cause corrosion due to interference. Furthermore, since iron tunnels have a large area to be protected against corrosion, it is necessary to properly dispose electrode materials in order to prevent corrosion over the entire area.However, since iron tunnels are often found in urban areas, such an arrangement is virtually impossible. Become.

As an anticorrosion method for this portion other than the external power source method, reinjection of mortar and painting can be considered. However, in the case of the existing structure, the former has no method to check whether or not the mortar has filled the outer circumference of the tunnel. Is peeled off and corrosion cannot be stopped. The latter cannot be implemented unless all the soil around Tonnenru is removed, so the cost is very high, and the workable locations are very limited.
The conventional corrosion protection technology for the outer circumference of the iron tunnel has the drawbacks described above.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and the outer surface of an existing iron tunnel that enables efficient corrosion protection of the outer peripheral portion of the 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 adopts the cathodic protection method having the following constitution.

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

The cathodic protection method of the present invention will be described below 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. After that, as shown in FIG. 1A, the tunnel wall surface, that is, the iron segment 1 is fused by the fusing jig 3. Next, as shown in FIG.
The grout layer 2 on the outer side of the iron segment 1 is pierced by the piercing jig 4.

Then, as shown in FIG. 1c, the iron segment 1
A reinforcing iron plate 5 having a hollow portion and a threaded portion is welded to the fusing portion. Then, as shown in FIG. 1d, the reinforcing iron plate 5
The electrode mounting bracket 19 to which the electrode material 6 is connected is inserted into the hollow portion of and is fixed by 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 member 19,
The backfill material 8 is injected into the void portion of the grout layer 2. Finally, as shown in FIG. 1f, after the backfill material 8 is filled in the gap between the electrode material 6 and the grout layer 2, the inlet 9 is plugged.
And connect the conducting wire.

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

3 to 6 are cross-sectional views taken along the line AA 'in FIG. 2, showing the attachment states of the 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 metal 10, for example, a magnesium alloy anode is penetrated and fixed in the threaded hole by screwing. After injecting a backfill material (for example, 30% by weight of bentonite, 30% by weight of gypsum and 20% by weight of tap water mixed with 20% by weight of tap water) from the core metal 10 through the backfill material inlet 11. A plug 9 is attached to the inner inlet of the core metal 10, and the core metal 10 and the reinforcing iron plate 5 are electrically connected by a conductive wire 12. In addition, 13 and 14 are an epoxy resin and a rubber packing, respectively.

4 is different from FIG. 3 in that
It is characterized in that the core metal is a combination of a rod-shaped core metal 10 ′ and a cylindrical electrode mounting fitting 19. Therefore, the backfill material is injected from the backfill material injection port 18 provided on the side surface of the mounting member 19, so that the weight of the electrode material can be increased and the life can be extended. Further, in the case of the structure of this device, an external electrode method 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 addition, in the same figure, 15 shows an electric wire.

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

For example, in FIG. 5, the hollow core metal 10
After the tapping is provided on the inside of one end of the electrode, the electrode material 6 is formed on the outside of the hollow cored bar 10 with a constant thickness except for one end. Next, on the outer side of one end of the hollow core metal 10, there is provided a cylindrical mounting member 19 having an outer diameter concentrically threaded.
A backfill material inlet 11 is provided at one end of the hollow core metal 10.
However, a backfill material injection port 18 is provided at the other end. The bag 17 for backfill material is fixed at the base of the electrode portion so that the backfill material 8 extends around the entire circumference of the electrode material 6, and the backfill material can be filled after being mounted on site. There is.

[0023]

According to the construction method of the present invention, the electrode material serving as the anode is directly attached to the body to be protected in the cathodic protection method of the existing iron tunnel to protect the limited area with one electrode material. This is a target construction method that does not cause interference with other buried objects or corrosion due to a jumping phenomenon, which has been a problem with this type of construction method.

This is achieved by calculating the corrosion protection current reaching range by an environmental survey such as the shape of the iron tunnel, the filling state of the grout layer, and the resistivity, and installing one electrode material in each range. It Also, when the electrode material is consumed, the electrode material attachment part is threaded, so it can be easily replaced with a new electrode material.Unlike the conventional underground burying method or welding method, replacement work is extremely easy. Is.

Further, in the hollow cored bar with an introduction port used in the present invention, after the electrode material is fixed to the body to be corroded by screwing, the hollow part of the hollow cored bar is used for the grout material or the backfill material. Used for injection. As a result, for example, when the water flow layer is not formed on the outer surface of the anticorrosion body, the backfill material is injected to eliminate the voids existing on the electrode material surface and the grout layer, and as a result, the low ground resistance of the electrode material is reduced. , Effective anticorrosion effect is exhibited. If there is a running water layer, grout material such as quick-setting mortar is injected.

If there is a possibility that the backfill material will be injected in a large amount, the backfill material may be added more than necessary by using an electrode material with a bag for the backfill material as shown in FIGS. Do not let it inject. The injection amount of the backfill material 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 voids and the like.

Although the mounting method using screws has been described above, another simple mounting method, for example, a method in which a flange portion is provided and fixed with bolts or the like may be used.

[0028]

EXAMPLES The present invention will be described below based on examples.

Example An example carried out on an actual iron segment will be shown. The segment tested was an FCD450 ductile segment, which has been in existence for more than 20 years.

Although mortar grout material is filled to the outside of the segment by 500 mm in design, some water leakage is observed from the gap between the segments, and there is a concern that the outer wall of the segment may be corroded.

In the test, first, the state of the grout layer and the state of voids were investigated by percussion and analysis of the percussion wave. Next, a 10 mmφ hole was opened at a position where the electrode material was to be attached, 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.

The construction was carried out by the procedure shown in FIGS. 1a to 1f. The length of the electrode portion was 300 mm. 500mm from the center of the electrode material to determine the effect, 1000
Saturated calomel electrodes were embedded at positions of mm, 1500 mm, and 2000 mm. At the time of embedding, a gel electrolyte obtained by dissolving 10% of carboxymethyl cellulose 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. The measurement result of this is shown in FIG.

As is clear from the results shown in FIG. 7, according to the change in the potential, the degree of polarization decreases as the distance from the electrode material increases. It was confirmed that the anti-corrosion effect 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 the potential measurement. When the electrode material is exhausted, it can be easily renewed, and once it collapses, it is extremely difficult to repair it, but the outer wall of the shield segment that cannot be visually recognized in the existing steel tunnel, which is a socially very important facility, It has an effect that corrosion damage can be protected for a long time.

Further, since the electrode is fixed by the screw method, the electrode material replacement when the electrode material is consumed is different from the conventional method of burying the electrode material in the soil or the welding method, which has been generally used in the cathodic protection method. It will be extremely easy. This will be effective for the maintenance of facilities such as electric railway tunnels where the working time is limited.

[Brief description of drawings]

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

FIG. 2 is a view showing a mounting state of an inside of an electrode device mounted on an iron segment.

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

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

FIG. 5 is a cross-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 changes in potential with time.

[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: Plug, 10: Hollow core metal,
11: Backfill material inlet, 12: Conductive wire, 13: Resin, 14: Rubber packing, 15: Electric wire, 16: Bag holder for backfill material, 17: Bag for backfill material, 18:
Backfill material inlet, 19: Electrode mounting bracket.

Claims (5)

[Claims] 1. After investigating the environmental conditions in contact with the outer surface of an existing iron tunnel, holes are made in the wall surface and soil of the tunnel, and a reinforcing iron plate having electrode through holes is welded to the inner surface of the wall.
After fixing a cylindrical electrode mounting bracket having a filler introduction port connected to the reinforcing iron plate with an electrode material so that the electrode material protrudes to the outer surface, the filler is fed from the filling material introduction port, A cathodic protection method for the outer surface of an existing iron tunnel, 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. 2. A reinforcing iron plate having an electrode through hole welded to an inner surface of an existing iron tunnel, a cylindrical electrode mounting metal fitting attached to the iron metal plate, a hollow core metal connected to the metal fitting, and the core. An electrode device for cathodic protection comprising an electrode material formed on the outside of gold. 3. A reinforcing iron plate having an electrode through hole welded to the inner surface of an existing iron tunnel, and attached to the iron plate,
An electrode device for cathodic protection comprising a cylindrical electrode mounting metal fitting having a filler injection port on its side surface, a core metal connected to the metal fitting, and an electrode material formed outside the core metal. 4. A reinforcing iron plate having an electrode through hole welded to an inner surface of an existing iron tunnel, a hollow core metal penetrating the iron plate, and an electrode mounting metal fitting concentrically fitted to an end portion of the core metal. An electrode device for cathodic protection comprising an electrode material formed on the outside of the core metal. 5. The electrode device for cathodic protection according to claim 2, further comprising a bag for a filler provided so as to cover the entire circumference of the electrode material.