JP2022159927A - Sacrificial anode burial method - Google Patents

Abstract

To provide a method for burying a sacrificial anode at a position where electric anticorrosion effect is fully stabilized with a required minimum excavation amount.SOLUTION: Provided is a method for burying a sacrificial anode A to be used when preventing corrosion of a steel foundation beam to be buried under the ground of an architectural structure, in which the sacrificial anode A is vertically buried in a vertical hole H1.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sacrificial anode embedding method.

Conventionally, for example, a basic structure as shown in Patent Document 1 below is known. This foundation structure consists of concrete piles that are buried in the soil and have multiple pile reinforcing bars inside, and a concrete floor that is set on the ground and has multiple slab reinforcing bars inside. It is interposed between a steel foundation part that connects the slab, the pile and the floor slab and is at least partially buried in the soil, at least one of the pile reinforcement and the slab reinforcement, and the soil. and an insulating member.
Also, a basic structure as shown in Patent Document 2 below is known. This foundation structure consists of concrete piles embedded in the soil and having pile reinforcing bars placed therein, steel foundations at least partially embedded in the soil, and at least a portion of the piles and foundations. and an insulating member disposed between the part.

JP 2019-085752 A Japanese Patent Application Laid-Open No. 2020-020210

Cathodic protection is sometimes used to prevent corrosion of steel foundation beams in buildings. Steel foundation beams of buildings are often constructed on the upper ground. On the other hand, when the sacrificial anode is buried in the upper layer ground of the same degree as the steel foundation beam, the anticorrosion effect is not stable. In other words, it is effective to dispose the sacrificial anode at a relatively deep position in the ground.
However, sacrificial anodes used for cathodic protection are generally buried horizontally. For this reason, when attempting to bury the sacrificial anode in a location where the effect of cathodic protection is stable, it is necessary to excavate a wide area of the surrounding ground. Therefore, there has been a problem in terms of labor required for excavation and costs for using an excavator.
Furthermore, depending on the number and arrangement of the components of the building, the arrangement of the components may be affected if the ground is to be excavated widely. Alternatively, since the sacrificial anode itself may interfere with the components of the building, it is difficult to bury the sacrificial anode horizontally in the basement of the building.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of burying a sacrificial anode in a position where the effect of cathodic protection is sufficiently stabilized with the minimum required amount of excavation.

In order to solve the above problems, the present invention proposes the following means.
A method of burying a sacrificial anode according to the present invention is a method of burying a sacrificial anode for use in preventing corrosion of a steel foundation beam buried underground in a building, characterized by vertically burying the sacrificial anode in a vertical hole. and

According to this invention, the sacrificial anode is vertically embedded. As a result, the area to be excavated can be made smaller than when the sacrificial anode is horizontally buried. Therefore, the excavation required for burying the sacrificial anode can be reduced in scale. Therefore, the cost and effort required for excavation can be reduced.
Furthermore, compared to the case of drilling a hole for horizontally burying the sacrificial anode, the hole can be drilled deeper without affecting the surrounding steel foundation beams and the like. Therefore, the sacrificial anode can be buried deeper. Therefore, by embedding in a location in the soil where electrical resistance is low, the effect of cathodic protection can be greatly improved.

Further, the sacrificial anode may be embedded below the lower end of the foundation member of the building.

According to this invention, the sacrificial anode is embedded below the lower end of the base member. This makes it possible to widen the range of steel foundation beams that are conducted by a single sacrificial anode.

Further, the sacrificial anode may be embedded substantially in the center of the steel foundation beam in plan view.

According to this invention, the sacrificial anode is embedded substantially in the center of the steel foundation beam in plan view. This allows a single sacrificial anode to conduct the entire steel foundation beam in the building. Therefore, by installing the sacrificial anode in one place, the entire steel foundation beam can be uniformly provided with the effect of cathodic protection.
In addition, by burying the sacrificial anode vertically, it is possible to bury the sacrificial anode at a relatively deep location as described above. Here, when the sacrificial anode is buried in the soil, the electric resistance decreases with increasing depth from the ground surface. Therefore, the sacrificial electrode can be placed in the soil where the electrical resistance is low. This makes it possible to make the above effects more remarkable.

The vertical hole in which the sacrificial anode is embedded may be characterized in that only a conductive cable can be embedded together with the sacrificial anode.

According to this invention, only the conductive cable can be embedded together with the sacrificial anode in the vertical hole in which the sacrificial anode is embedded. Thereby, the size of the hole in which the sacrificial anode is embedded can be minimized. Therefore, it is possible to improve the work efficiency by reducing the size of the drilling of the hole for burying the sacrificial anode.

Further, the steel foundation beam may have a region where the components of the steel foundation beam do not overlap in plan view, and the sacrificial anode may be embedded in the vertical hole provided in the region.

According to the invention, the sacrificial anodes are embedded in holes provided in areas where the steel foundation beams do not overlap. As a result, the sacrificial anode can be embedded without affecting the configuration of the steel foundation beam in plan view. Therefore, the degree of freedom in designing the steel foundation beams in the building can be improved.

According to the present invention, it is possible to provide a method of burying a sacrificial anode in a position where the effect of cathodic protection is sufficiently stabilized with the minimum required amount of excavation.

It is a schematic diagram of sacrificial anode embedding according to one embodiment of the present embodiment. It is a schematic diagram of the conventional sacrificial anode embedding. It is a schematic diagram of an electric circuit used for cathodic protection of steel foundation beams. 4 is a schematic diagram of an electrode arrangement according to the electric circuit shown in FIG. 3; FIG.

Hereinafter, a sacrificial anode embedding method according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the sacrificial anode A is a rod-shaped member. A conducting cable C is connected to one end of the sacrificial anode A. As shown in FIG. As the sacrificial anode A, a magnesium alloy anode is preferably used mainly. The sacrificial anode A is, for example, a circle with a diameter of 150 to 200 mm and a length of 1200 md, in which the circumference of the magnesium alloy anode housed in a cloth bag is filled with a backfill having a role of stabilizing the anode potential. A columnar shape is preferably used.
As shown in FIG. 1, the sacrificial anode A according to this embodiment is embedded in the vertical hole H1. At this time, the sacrificial anode A is arranged so that one end faces upward and the other end faces the bottom of the vertical hole H1. That is, in the embedding method of this embodiment, the sacrificial anode A is vertically embedded in the vertical hole H1. The vertical hole H1 means a hole whose vertical depth is greater than its horizontal width. The vertical embedding of the sacrificial anode A also includes the case where the longitudinal direction of the sacrificial anode A is inclined at an angle of about 15 degrees with respect to the vertical direction.

By being buried in the ground, the sacrificial anode A conducts through the soil in the ground to the steel foundation beams 11 that are similarly constructed in the ground. This creates a potential difference with the soil in the ground, and prevents the steel foundation beams 11 from corroding in the ground (electrolytic protection).
In this cathodic protection, the other end of the sacrificial anode A is preferably embedded below the lower end of a foundation member (for example, footing) such as the steel foundation beam 11 of the building. As a result, by increasing the range of the steel foundation beam 11 that is electrically connected by one sacrificial anode A, the number of sacrificial anodes A to be installed is minimized.

The vertical hole H1 is mainly provided in the basement of the building. Specifically, in a plan view of the building, it is provided in a region where constituent elements of steel foundation beams 11 (described later) that are constructed as the foundation of the building do not overlap. This prevents the steel foundation beam 11 from interfering with the excavation of the vertical hole H1.
The diameter of the vertical hole H1 is preferably about 1.5 to 3 times the diameter of the sacrificial anode A (300 to 600 mm). Within the above range, it will be determined as appropriate in consideration of workability at the site. Moreover, as described above, the depth of the vertical hole H1 is preferably such that the other end of the sacrificial anode A is embedded below the lower end of the foundation member including the steel foundation beam 11 of the building.
Here, the steel foundation beam 11 in this embodiment is buried so that the lower end is about 1 m deep. Therefore, it is preferable that the vertical hole H1 is excavated to a depth of about 1 to 2.5 m. Moreover, it is preferable that only the conductive cable C can be embedded together with the sacrificial anode A in the vertical hole H1. For example, the volume of the vertical hole H1 is preferably about 500 to 1900% of the sacrificial anode A. This ensures that the size of the vertical hole H1 is minimized.

Here, as shown in FIG. 2, consider the case where the sacrificial anode A is horizontally arranged in the lateral hole H2. In this case, the area of the ground that needs to be excavated for burying the sacrificial anode A increases. Furthermore, if it is attempted to provide the sacrificial anode A below the lower end of the base member as described above, it is necessary to excavate a correspondingly deep hole. Therefore, it becomes necessary to use a large-scale excavator or secure a wider area. On the other hand, by using the vertical hole H1 shown in FIG. 1, it is possible to excavate the hole with necessary and sufficient depth more easily. Therefore, it becomes possible to arrange the sacrificial anode A at a sufficient depth more easily. Furthermore, since a large area is not required, the degree of freedom in designing the steel foundation beam 11 is also improved.
Conductive cable C is connected to one end of sacrificial anode A at one end. Also, the other end is connected to the connection box 30 (described later). It is preferable to use a known cable as the conductive cable C after appropriately selecting it.

Next, the correlation between the position and depth of the sacrificial anode A on the steel foundation beam 11 and the effect of cathodic protection will be described.
Table 1 shows the relationship between the depth at which the sacrificial anode A is arranged in the soil and the resistance value. As shown in Table 1, the resistance value decreases as the depth (measured depth) in the soil increases. That is, the deeper the soil, the easier it is for the anticorrosion current to flow.

As shown in FIG. 3, the anti-corrosion circuit 100 is arranged on the steel base beam 11 formed in a rectangular shape, the first electrode 1 is arranged at the corner of the rectangular shape, and the first electrode 1 is arranged at the substantially center of the rectangular shape. The second electrode 2 is compared. Both the first electrode 1 and the second electrode 2 are sacrificial anodes A. FIG.
4 shows the anti-corrosion circuit 100 arranged in FIG. As shown in FIG. 4, the anticorrosion circuit 100 includes a main circuit 10, a measurement circuit 20, and a connection box 30. As shown in FIG.

The main circuit 10 is a part that loads the steel foundation beam 11 with an anti-corrosion current. The main circuit 10 includes a first electrode 1 , a second electrode 2 , an underground circuit 3 , a crossover wire 4 , a connecting wire 5 , a steel foundation beam 11 and a terminal 12 .
The first electrode 1 is a sacrificial anode A aggregated together with the measuring circuit 20 and the terminal 12 etc. in the first junction box 31 . (described later).
A second electrode 2 is a sacrificial anode A integrated in a second junction box 32 . Only the second electrodes 2 are collected in the second connection box 32 (described later).

The underground circuit 3 connects the first electrode 1 and the second electrode 2 with the steel foundation beam 11 and the measuring circuit 20 . The underground circuit 3 shown in FIG. 4 is a schematic one, and the underground circuit 3 is soil in the ground in which the anti-corrosion circuit 100 is buried. As the soil conducts between the first electrode 1 and the second electrode 2 and the steel foundation beam 11 in this manner, an anticorrosion current flows in the anticorrosion circuit 100 .

The crossover wire 4 connects the first junction box 31 and the second junction box 32 . Thereby, the second electrode 2 connected to the second connection box 32 and the steel base beam 11 connected to the first connection box 31 are electrically connected.
The connection line 5 connects each component in the anticorrosion circuit 100 . In particular, it connects between the first junction box 31 and the first electrode 1 , the terminal 12 and the measuring circuit 20 and between the second junction box 32 and the second electrode 2 .
A known conducting cable C, for example, is suitably used for the crossover wire 4 and the connecting wire 5 .

The steel foundation beam 11 is a target for anticorrosion by the anticorrosion circuit 100 . The steel foundation beam 11 is connected to the first junction box 31 via the terminal 12 .
Terminal 12 is provided between steel foundation beam 11 and second junction box 32 . The terminal 12 thereby measures the potential between the steel foundation beam 11 and the second junction box 32 . The measured potential is used together with the potential measured in the measuring circuit 20 to analyze the resistance value in the corrosion protection circuit 100 .

The measurement circuit 20 measures the potential in the anticorrosion circuit 100 . Measurement circuit 20 comprises a zinc reference electrode 21 and a probe electrode 22 .
A zinc reference electrode 21 is buried in the ground to measure the potential. The probe electrode 22 has a role of removing an error in the measured potential when the steel foundation beam 11 to be protected against corrosion is coated with a highly insulating film. The probe electrode 22 also serves to confirm that the anticorrosion current is actually flowing through the anticorrosion circuit 100 .
Known zinc reference electrodes 21 and probe electrodes 22 are preferably used.

The junction box 30 aggregates the connecting wires 4 and connecting wires 5 of the main circuit 10 and the measuring circuit 20 . The junction box 30 has a first junction box 31 and a second junction box 32 .
A first junction box 31 aggregates the connection lines 5 connected to the first electrode 1 , the zinc reference electrode 21 and the probe electrode 22 of the measurement circuit 20 and the terminal 12 . The first junction box 31 and the second junction box 32 are connected by a crossover wire 4 .
The second connection box 32 mainly collects only the connection wires 5 connected to the second electrodes 2 .

The anti-corrosion circuit 100 configured in this way is arranged inside the steel foundation beam 11 as shown in FIG. As shown in FIG. 2, the first electrode 1 is horizontally buried at a depth of 1.0 m from the ground surface. As shown in FIG. 1, the second electrode 2 is vertically buried so that the other end of the second electrode 2 is at a height of 2.5 m from the ground surface. Table 2 shows the resistance values measured under these conditions.

As shown in Table 2, it was confirmed that the resistance value of the vertically arranged second electrode 2 was about half of the resistance value of the horizontally arranged first electrode 1 .

As described above, according to the sacrificial anode embedding method according to the present embodiment, the sacrificial anode A is vertically embedded. As a result, the excavation range can be made smaller than when the sacrificial anode A is horizontally buried. Therefore, the excavation required for burying the sacrificial anode A can be reduced in scale. Therefore, the cost and effort required for excavation can be reduced.
Furthermore, compared with the case of drilling a hole for horizontally burying the sacrificial anode A, the hole can be drilled deeper without affecting the surrounding steel foundation beams 11 and the like. Therefore, the sacrificial anode A can be buried at a deeper location. Therefore, by embedding in a location in the soil where electrical resistance is low, the effect of cathodic protection can be greatly improved.

Also, a sacrificial anode A is embedded below the lower end of the base member. As a result, the range of the steel foundation beams 11 that are electrically connected by the sacrificial anode A at one location can be widened.

In addition, the sacrificial anode A is embedded substantially in the center of the steel foundation beam 11 in plan view. As a result, the entire steel foundation beam in the building can be conducted by the sacrificial anode A at one location. Therefore, by installing the sacrificial anode A in one place, the entire steel foundation beam can be uniformly provided with the effect of cathodic protection.
Moreover, by burying the sacrificial anode A vertically, the sacrificial anode A can be buried in a relatively deep place as described above. Here, when the sacrificial anode A is buried in the soil, the electric resistance becomes smaller as the position becomes deeper from the ground surface. Therefore, the sacrificial electrode can be placed in the soil where the electrical resistance is low. This makes it possible to make the above effects more remarkable.

Further, only the conductive cable C can be embedded together with the sacrificial anode A in the vertical hole H1 in which the sacrificial anode A is embedded. Thereby, the size of the hole in which the sacrificial anode A is embedded can be minimized. Therefore, the work efficiency can be improved by minimizing the excavation of the hole in which the sacrificial anode A is to be embedded.

Moreover, the sacrificial anode A is embedded in a hole provided in a region where the steel foundation beam 11 does not overlap. As a result, the sacrificial anode A can be buried without affecting the structure of the steel foundation beam 11 in plan view. Therefore, the degree of freedom in designing the steel foundation beam 11 in the building can be improved.

The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.
For example, a plurality of first electrodes 1 and second electrodes 2 may be provided on the steel foundation beam 11 .

In addition, it is possible to appropriately replace the constituent elements in the above-described embodiment with well-known constituent elements without departing from the spirit of the present invention, and the modifications described above may be combined as appropriate.

11 Steel foundation beam A Sacrificial anode C Continuity cable H1 Vertical hole

Claims (5)

A method of embedding a sacrificial anode used to prevent corrosion of a steel foundation beam buried underground in a building, comprising:
characterized by embedding the sacrificial anode vertically in a vertical hole,
Sacrificial anode embedding method. The sacrificial anode is embedded below the lower end of a foundation member in the building,
2. The sacrificial anode embedding method according to claim 1. The sacrificial anode is embedded substantially in the center of the steel foundation beam in plan view,
3. The sacrificial anode embedding method according to claim 1 or 2. In the vertical hole in which the sacrificial anode is embedded, only a conductive cable can be embedded together with the sacrificial anode,
4. The sacrificial anode embedding method according to claim 1 or 3. The steel foundation beam has a region where the components of the steel foundation beam do not overlap in plan view,
The sacrificial anode is embedded in the vertical hole provided in the region,
The sacrificial anode embedding method according to any one of claims 1 to 4.

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