JP7175234B2 - Monitoring system and monitoring method - Google Patents

Description

Embodiments of the present invention relate to monitoring systems and methods.

Conventionally, a basic structure as shown in Patent Document 1, for example, is known. This foundation structure consists of concrete piles that are buried in the soil and have multiple pile reinforcing bars inside, and concrete piles that are installed on the surface of the soil and have multiple slab reinforcing bars inside. and a steel foundation connecting the piles and the floor slab and at least partially embedded in the soil.
The foundation includes a steel pile head joint connected to the upper end of the pile, a steel support section extending upward from the pile head joint, and a floor slab extending horizontally from the support section. supporting steel foundation beams.
In this foundation structure, not only microcell corrosion in general soil but also concrete soil macrocell corrosion (hereinafter referred to as "CS macrocell corrosion") occurs. In this foundation structure, since the pile reinforcing bars and slab reinforcing bars are electrically connected to the foundation, a potential difference is generated between them, and the foundation becomes an anode. The reinforcing bar becomes the cathode, and a cathodic reaction occurs in pile reinforcing bars and slab reinforcing bars, and a corrosion current flows from the anode to the cathode through the soil, and CS macrocell corrosion occurs in the base portion, which is the anode. At this time, the potential of the base shifts to the noble side.
In order to prevent CS macro-cell corrosion and micro-cell corrosion, there is a technique of applying a coating to the steel base and applying cathodic protection such as a magnesium alloy anode. In this technology, when a sufficient anti-corrosion current density flows into the paint defect of the steel foundation, the ground potential of the steel foundation, which was on the noble side, shifts to the base side, and the ground potential is more negative than the corrosion protection potential. , the corrosion protection of the steel foundation is achieved.
In cathodic protection, the required corrosion current generator (eg, magnesium alloy anode) is designed to provide the required corrosion current density to the steel foundation of interest.
However, when another metal object comes into contact with the target steel foundation, the anti-corrosion current generated from the magnesium alloy anode also flows into other metals other than the target steel foundation. The corrosion protection current density of the required steel foundation falls below the value reaching the protection potential. As a result, even though the steel foundation is applied with cathodic protection, the corrosion potential is not reached due to metal contact with other metals, and corrosion occurs. At this time, the generated current of the magnesium alloy anode in the vicinity of the portion of metal contact increases. Other metal objects that come into contact with steel foundations include lead-in pipes to steel buildings, metal objects left over from construction, and other metal objects in the ground.
In addition, if a steel foundation is installed in the soil where a stray current is flowing due to a direct current electric railway, etc., the stray current is a concrete pile containing a steel foundation that is a low-grounding structure. It flows in and out of the magnesium alloy anode. Where the stray current flows in, the potential shifts to the base side, providing the same anticorrosion effect as in cathodic protection, but where it flows out, the ground potential shifts to the noble side, causing stray current corrosion (electrolytic corrosion). Occur. Interference is a phenomenon in which the ground potential of an object shifts to the negative side or the noble side due to the inflow and outflow of stray currents.
At this time, when the stray current flows into the magnesium alloy, the ground potential of the anode becomes base and the generated current of the anode is suppressed. As the becomes nobler, the current generated at the anode increases by the stray current, and the anode dissolution progresses by the current increase. As a result, a problem arises that the anode is consumed before the service life of the anode expected in the anode design.

JP 2005-068953 A

Even if the steel foundation is galvanically protected, the steel foundation may not reach the anticorrosion potential for the reason described above. The reasons why the steel foundation does not reach the corrosion protection potential are that all the steel materials (mainly reinforcing bars) that are electrically connected to the steel foundation come into contact with other metal objects (low-grounding objects), and the stray from electric railways, etc. It is assumed that a stray current flows out due to current interference.
However, it is difficult to identify where and why the corrosion protection potential of the steel foundation is not reached. For this reason, in pipelines, techniques are being developed to detect locations where the anticorrosion potential is not reached. For example, when a pipeline is in contact with another metal, one method of detecting the contact position is the magnetic sensor method. In this method, a current is passed through the pipeline, and the magnetic field generated by the current flowing through the pipeline is continuously measured along the pipeline using a magnetic sensor. Therefore, the magnitude of the magnetic field changes before and after contact, and the contact position with the metal object is detected from the point of inflection of the magnitude of the magnetic field. This method is effective for simple stretched structures such as pipelines, but for complex structures such as steel foundations, even if you try to measure the magnetic field by passing an electric current through the steel foundation, The overlapping magnetic fields make it impossible to detect the contact position of a metallic object. Thus, techniques developed for pipelines cannot be applied to steel foundations.

The present invention has been made in view of the above-mentioned circumstances, and provides a monitoring system and a monitoring method that can identify the cause of the failure of the steel foundation to reach the corrosion protection potential when the steel foundation has been subjected to cathodic protection. intended to provide

(1) A monitoring system according to an aspect of the present invention includes concrete piles embedded in soil and having a plurality of pile reinforcing bars arranged inside, and a plurality of concrete piles installed on the surface of the soil and inside a plurality of piles. a concrete floor slab on which slab reinforcing bars are arranged; and a steel foundation that connects the pile and the floor slab and is at least partly buried in the soil, the foundation includes a steel pile head joint connected to the upper end of the pile, a steel support pillar extending upward from the pile head joint, and a steel pillar extending horizontally from the pillar and supporting the floor slab. A current supply unit that supplies an anticorrosion current to the foundation part of the foundation structure that includes a steel foundation beam that supports a steel foundation beam, a reception unit that receives information indicating the ground potential of the foundation part of the foundation structure, and the reception unit that receives Based on the information indicating the ground potential, it is determined whether or not a low-grounding object is in contact with the foundation, and whether current outflow due to interference of stray current is occurring in the steel foundation. and a processing unit that performs either one or both of determination.

According to the invention, a monitoring system receives information indicative of the ground potential of steel foundation beams of a foundation structure. For this reason, based on the received information indicating the ground potential, the monitoring system determines that the foundation is in contact with a low-grounding object and that a current outflow occurs in the steel foundation due to the interference of the stray current. or both.

(2) A monitoring system according to an aspect of the present invention is the monitoring system according to (1) above, wherein the receiving unit receives information indicating anticorrosion current generated by an anode, and the processing unit receives Further, based on the information indicating the anti-corrosion current received by the unit, it is determined whether or not a low-grounding object is in contact with the base portion, and whether current outflow due to interference of stray current has occurred. Do either or both of

In this case, the reception unit receives information indicating the anticorrosion current generated by the anode. Therefore, based on the received information indicating the anti-corrosion current, the monitoring system determines whether the foundation is in contact with a low grounding object and whether the current outflow occurs in the steel foundation due to the interference of the stray current. and/or

(3) A monitoring system according to an aspect of the present invention is the monitoring system according to (1) or (2) above, wherein the reception unit includes the base unit of each of the plurality of base structures. Information indicating ground potential is received, and based on the information indicating the ground potential of each of the foundations of the plurality of foundation structures received by the receiving unit, the monitoring system detects whether a low-grounding object is in contact with the foundation. and a position where current outflow occurs due to interference of stray currents, or both.

In this case, the monitoring system receives information indicating ground potentials of foundation beams of each of the plurality of foundation structures. Therefore, based on the received information indicating a plurality of ground potentials, the monitoring system determines which of the positions where the foundation beam is in contact with the low-grounding object and the position where current outflow occurs due to interference of stray currents. Either one or both can be derived.

(4) A monitoring system according to an aspect of the present invention is the monitoring system according to (3) above, wherein the specifying unit is based on a plane defined by information indicating the ground potentials at at least three locations. , derivation of the position where the low-grounding object is in contact with the base portion and/or derivation of the position where current outflow occurs due to interference of stray currents.
In this case, the monitoring system receives information indicating ground potentials at at least three locations. For this reason, the monitoring system derives the position where the low-grounding object is in contact with the foundation based on the plane defined by the received information indicating the ground potential of at least three points, and calculates the current outflow due to the interference of stray current. derivation of the position at which is occurring, or both.

(5) A monitoring system according to an aspect of the present invention is the monitoring system according to (1) above, wherein each of the plurality of current supply units is a base of each of the plurality of basic structures. receiving information indicating the anti-corrosion current generated by each of the plurality of anodes by supplying current to the unit, and based on the information indicating the anti-corrosion current generated by each of the plurality of anodes received by the receiving unit, A specifying unit that performs one or both of derivation of a position where a low-grounding object is in contact with the base part and derivation of a position where current outflow occurs due to interference of stray currents.
In this case, the monitoring system receives information indicative of the protection current generated by each of the plurality of anodes. Therefore, based on the received information indicating the anticorrosion current generated by each of the plurality of anodes, the monitoring system derives the position where the low-grounding object is in contact with the foundation and prevents the current outflow due to the interference of the stray current. and/or derivation of the location of occurrence.

(6) A monitoring method according to an aspect of the present invention includes a concrete pile embedded in the soil and having a plurality of pile reinforcing bars arranged inside, and a concrete pile installed on the surface of the soil and having a plurality of piles inside. a concrete floor slab on which slab reinforcing bars are arranged; and a steel foundation that connects the pile and the floor slab and is at least partly buried in the soil, the foundation includes a steel pile head joint connected to the upper end of the pile, a steel support pillar extending upward from the pile head joint, and a steel pillar extending horizontally from the pillar and supporting the floor slab. a step of supplying an electric current to the base portion of a foundation structure comprising a steel foundation beam and a step of receiving information indicating the ground potential of the foundation portion of the foundation structure; and the ground potential received in the receiving step Based on the information indicating, either or both of determining whether or not a low-grounding object is in contact with the base portion and determining whether or not current outflow due to interference of stray current has occurred. A monitoring method executed by a monitoring system having steps.

(7) A monitoring method according to an aspect of the present invention is the monitoring method according to (6) above, wherein in the receiving step, information indicating the ground potential of the base portion of each of the plurality of the base structures and the monitoring method determines a position where a low grounding object is in contact with the foundation based on the information indicating the ground potential of the foundation of each of the plurality of foundation structures received in the receiving step. There is a specific step of deriving and/or deriving the location where current outflow due to interference of stray currents is occurring.
(8) A monitoring method according to an aspect of the present invention is the monitoring method according to (7) above, wherein the floor slab of each of the plurality of foundation structures is provided with a potential measuring device for measuring the ground potential. is installed, and in the identifying step, either the derivation of the position of the floor slab where the low-grounding object is in contact with the foundation or the derivation of the position of the floor slab where current outflow due to interference of stray currents occurs either or both.

(9) A monitoring method according to an aspect of the present invention is the monitoring method according to (6) above, wherein in the receiving step, by supplying a current to each base portion of the plurality of base structures, Information indicating the anticorrosion current generated by each of the plurality of anodes is received, and the monitoring method includes: receiving information indicating the anticorrosion current generated by each of the plurality of anodes received in the receiving step; It has a specific step of deriving one or both of derivation of a position where a low-grounding object is in contact and derivation of a position where current outflow occurs due to interference of stray currents.
(10) A monitoring method according to an aspect of the present invention is the monitoring method according to (9) above, wherein the floor slab of each of the plurality of foundation structures is provided with a current measuring device for measuring the anticorrosion current. is installed, and in the identifying step, either derivation of the position of the floor slab where the low-grounding object is in contact with the base part or derivation of the position of the floor slab where current outflow due to interference of stray current occurs either or both.

According to the embodiment of the present invention, when the steel foundation beam is galvanically protected, the presence or absence of contact with other metals, which is the cause of the foundation beam not reaching the corrosion protection potential, and the current due to the interference of the stray current It is possible to specify the presence or absence of outflow and the outflow position.

Fig. 2 shows a basic structure according to an embodiment of the present invention; It is a figure which shows an example of the monitoring system which concerns on embodiment of this invention. It is a figure which shows an example of a base-slab. 1 is a block diagram showing a monitoring device that constitutes a monitoring system according to an embodiment of the present invention; FIG. It is a figure which shows an example of the dimension of a foundation beam. It is a figure which shows an example of the installation position of a reference electrode. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a metal contact position. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a base-slab. It is a figure which shows an example of the installation position of a reference electrode. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a metal contact position. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a steel foundation beam. FIG. 4 is a diagram showing an example of temporal changes in current generated by a magnesium alloy anode when a metal object is in contact. FIG. 4 is a diagram showing an example of a time-dependent change in generated current of a magnesium alloy anode at an outflow location of a stray current. It is a flow chart which shows an example of operation of a surveillance system of this embodiment. It is a flow chart which shows an example of operation of a surveillance system of this embodiment.

Next, the monitoring system and monitoring method of this embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and embodiments to which the present invention is applied are not limited to the following embodiments.
In addition, in all the drawings for explaining the embodiments, the same reference numerals are used for the parts having the same functions, and repeated explanations are omitted.
In addition, "based on XX" in the present application means "based on at least XX", and includes cases based on other elements in addition to XX. Moreover, "based on XX" is not limited to the case of using XX directly, but also includes the case of being based on what has been calculated or processed with respect to XX. "XX" is an arbitrary element (for example, arbitrary information).

(embodiment)
(Fundamental structure)
FIG. 1 is a diagram showing a basic structure according to an embodiment of the invention.
As shown in FIG. 1, the foundation structure 1 according to the present embodiment includes concrete piles 10 embedded in the soil D and having a plurality of pile reinforcing bars 11 disposed inside, and is installed on the ground G, A concrete floor slab 20 having a plurality of slab reinforcing bars 21 arranged inside, and a steel foundation 30 connecting the piles 10 and the floor slab 20 and having at least a portion buried in the soil D. and a current supply unit 51 for supplying an anti-corrosion current to the base portion 30 . The basic structure 1 employs the cathodic protection method.
In the following description, the direction in which the piles 10 extend is referred to as the vertical direction X, and the direction perpendicular to the vertical direction X is referred to as the horizontal direction.

The pile 10 has a tubular shape. A plurality of pile reinforcing bars 11 are arranged inside the peripheral wall of the pile 10 . A plurality of pile reinforcing bars 11 are formed in the vertical direction X and in a spiral shape at intervals in the circumferential direction.
The floor slab 20 has a plate-like shape with front and back surfaces facing in the vertical direction X, and has a rectangular shape when viewed from above. Inside the floor slab 20, a plurality of slab reinforcing bars 21 are arranged at intervals in the horizontal direction.

The base portion 30 includes a steel pile head joint portion 31 connected to the upper end portion of the pile 10, a steel column portion 32 extending upward from the pile head joint portion 31, and a steel column portion 32 extending horizontally from the column portion 32. a steel base beam 33 extending and supporting the floor slab 20;
The pile head joint 31 has a truncated tubular shape. A strut portion 32 is erected on the top of the pile head joint portion 31 .
The pile head joint 31 is in contact with the pile reinforcing bar 11 . Thereby, the pile head joint portion 31 and the pile reinforcing bar 11 are electrically connected to each other. The upper end portion of the pile reinforcing bar 11 is in contact with the lower end opening edge of the pile head joint portion 31 .

The strut part 32 extends upward from the ground G. As shown in FIG. The pillars 32 are arranged at the four corners of the floor slab 20 when viewed from above. In the illustrated example, H-steel having an H-shape when viewed from above is used as the support 32, but a square steel pipe or the like may also be used.
A plurality of foundation beams 33 are connected to the supporting column 32 . The foundation beams 33 are arranged on the periphery of the floor slab 20 in a top view, have a rectangular shape, and support the floor slab 20 from below.

The foundation beam 33 is an H-steel having an H-shape when viewed from the extending direction. Flange portions 33B whose front and rear surfaces face the vertical direction X are separately connected to both ends in the vertical direction X of the web 33A whose front and rear surfaces face the direction perpendicular to the extension direction of the base beam 33 .
A stud dowel 34 protruding upward is provided on the upper surface of the upper flange portion 33B of the foundation beam 33 . A plurality of stud dowels 34 are arranged at intervals along the extending direction of the foundation beam 33 on the upper surface of the flange portion 33B. The foundation beams 33 are connected to the slab reinforcing bars 21 via stud dowels 34 . Thereby, the foundation beam 33 and the slab reinforcement 21 are electrically connected to each other.

In the present embodiment, the foundation structure 1 further includes a first insulating member 40 interposed between at least one of the pile reinforcing bars 11 and the slab reinforcing bars 21 and the soil D and having a higher electrical resistance than the soil D. there is In this embodiment, the first insulating member 40 is interposed between both the pile reinforcement 11 and the slab reinforcement 21 and the soil D separately. The first insulating member 40 includes a slab insulating member 41 interposed between the slab reinforcing bar 21 and the soil D, and a pile insulating member 42 interposed between the pile reinforcing bar 11 and the soil D. Note that the first insulating member 40 may be interposed between the soil D and either one of the pile reinforcing bars 11 and the slab reinforcing bars 21 without being limited to such an aspect.
The first insulating member 40 is interposed between the pile 10 and the soil D or between the floor slab 20 and the soil D. In this embodiment, the slab insulating member 41 is interposed between the floor slab 20 and the soil D, and the pile insulating member 42 is interposed between the pile 10 and the soil D.

The slab insulating member 41 is made of asphalt. The slab insulating member 41 is arranged above the crushed cobblestone 22 laid on the ground G and below the floor slab 20 . The slab insulating member 41 is interposed over the entire lower surface of the floor slab 20 . In addition, the slab insulating member 41 may be interposed in a part of the lower surface of the floor slab 20 . By interposing the slab insulating member 41 between the floor slab 20 and the soil D in this manner, the first insulating member 40 is interposed between the slab reinforcing bar 21 and the soil D.
Note that the slab insulating member 41 is not limited to asphalt. For example, any highly insulating organic material such as a polyethylene sheet or an insulating rubber sheet can be applied to the slab insulating member 41 .

The pile insulation member 42 is painted on the outer peripheral surface of the pile 10 . The pile insulating member 42 is painted on the upper portion of the outer peripheral surface of the pile 10 . Thus, the pile insulation member 42 is interposed between the pile reinforcement 11 and the soil D by coating the pile insulation member 42 on the outer peripheral surface of the pile 10 .
Note that the pile insulating member 42 is not limited to being painted. For example, any organic material having high insulating properties such as asphalt, polyethylene sheet, insulating rubber sheet, etc. can be applied to the pile insulating member 42 .

Here, the dimension in the vertical direction X from the ground G to the lower end of the pile insulating member 42 is set to 5 m, for example. In the portion of the soil D located below 5 m from the ground G, the content (concentration) of oxygen required for the cathodic reaction, which will be described later, is extremely low. Therefore, the pile insulating member 42 is not provided in the portion of the pile 10 located 5 m or less from the ground G. The length in the vertical direction X from the ground G to the lower end of the pile insulating member 42 may be 5 m or less, or may be 5 m or more. Moreover, the outer surface of the pile 10 may be coated with the pile insulating member 42 over the entire area in the vertical direction X.

In the foundation structure 1, the potential of the steel foundation part 30 buried in the soil D (for example, -0.6 V saturated copper sulfate electrode standard) is the same as that of the reinforcing bars (pile reinforcing bars 11, slab reinforcing bars 21) (eg -0.3V saturated copper sulfate electrode reference). Therefore, the base portion 30 with a low potential becomes an anode, and the pile reinforcing bars 11 and slab reinforcing bars 21 with high potential become cathodes, and corrosion current flows from the anode (foundation portion 30) through the soil D to the cathodes (pile reinforcing bars 11 and slab reinforcing bars 21). flow, CS macrocell corrosion is about to occur.
At this time, an anodic reaction represented by the following formula (1) occurs in the base portion 30 , and a cathodic reaction represented by the following formula (2) occurs in the pile reinforcing bars 11 and the slab reinforcing bars 21 .

Fe→Fe ²⁺ +2e ⁻ (1)
1/2O ₂ +H ₂ O+2e ⁻ →2OH ⁻ (2)

(Cathodic protection)
The current supply 51 is a sacrificial anode 52 . The sacrificial anode 52 is buried in the soil D. The sacrificial anode 52 is electrically connected to the base portion 30 . Among the sacrificial anodes 52 in the soil D, the potential of the magnesium alloy anode (eg, −1.5 V, based on saturated copper sulfate electrode) is lower than the potential of the base portion 30 in the soil D (eg, −0.6 V). Therefore, based on this potential difference, the sacrificial anode 52 can be used as an anode and the base portion 30 can be used as a cathode, and an anti-corrosion current can flow through the soil D from the anode to the cathode. In the illustrated example, the sacrificial anode 52 is made of magnesium alloy or magnesium, and the anode reaction represented by the following formula (3) occurs at the sacrificial anode 52 .
Mg→Mg ²⁺ +2e ⁻ (3)
It should be noted that, instead of magnesium alloy or magnesium, for example, zinc alloy or zinc may be used as the material forming the sacrificial anode 52 .

According to the foundation structure 1 according to this embodiment, the first insulating member 40 is interposed between the soil D and at least one of the pile reinforcing bars 11 and the slab reinforcing bars 21 . For this reason, among the pile reinforcing bars 11 and the slab reinforcing bars 21 (cathode) placed in the concrete, for example, in a portion located in a region where the oxygen concentration in the soil D is high, the cathode reaction represented by the above equation (2) It is possible to suppress the occurrence of , and to suppress the flow of current from the soil D to the pile reinforcing bars 11 and the slab reinforcing bars 21 . As a result, the total amount of corrosion current can be suppressed to reduce the corrosion current density in the anode (base portion 30), and CS macrocell corrosion in the base portion 30 can be suppressed.

Further, by interposing the first insulating member 40 between the pile 10 or the floor slab 20 and the soil D, the pile reinforcement 11 or the slab reinforcement 21 can be insulated from the soil D. This makes it easier to insulate the pile reinforcing bars 11 or the slab reinforcing bars 21 than, for example, a configuration in which the outer surface of each of the plurality of pile reinforcing bars 11 or the plurality of slab reinforcing bars 21 is individually covered with the first insulating member 40. It can be carried out.

Further, according to the base structure 1 of the present embodiment, the current supply part 51 supplies the anticorrosion current to the base part 30 . Therefore, the potential of the foundation 30 in the soil D, which has been transferred to the noble side, is changed by the anticorrosion current to the natural potential of the foundation 30 when, for example, CS macrocell corrosion does not occur, as well as general soil corrosion. It can be made base to the anticorrosion potential at which microcell corrosion does not occur. Thus, the cathodic protection can suppress the CS macrocell corrosion and the microcell corrosion of the base portion 30 by the cathodic protection method.
The cathodic protection must be designed so that the foundation 30 has a design service life and corrosion protection potential. Specifically, the anticorrosion current density (for example, 0.02 A/m ² ) required for the base portion 30 to reach the anticorrosion potential is multiplied by the surface area of the base portion 30 to be subjected to cathodic protection, and the necessary anticorrosion Calculate the current and determine the mass, geometry, and number of sacrificial anodes 52 that can supply the anticorrosion current for the service life.

In addition, in this embodiment, since the foundation 30 and the pile reinforcing bars 11 and the slab reinforcing bars 21 are electrically connected, the anti-corrosion current of the sacrificial anode 52 is applied not only to the base part 30 but also to the insulating materials of the pile reinforcing bars 11 and the slab reinforcing bars 21. An anti-corrosion current flows into the defect.
Therefore, in designing the sacrificial anode 52 , the mass, shape, size, and number of the sacrificial anode 52 are determined by adding the current flowing into the pile reinforcement 11 and the slab reinforcement 21 in addition to the foundation 30 .

(Influence of contact with other metal objects under cathodic protection)
Cathodic protection is designed so that the range into which the protection current flows is determined, and the target of the protection is the protection potential. When the metal part of the foundation structure 1 to be protected from corrosion comes into contact with another metal object, the anti-corrosion current also flows into the contact metal object, so the range of the inflow of the anti-corrosion current expands, and the corrosion prevention target is originally The anticorrosion current density to flow into the base portion 30 made of steel decreases, and the base portion 30 does not reach the anticorrosion potential and becomes a potential considerably nobler (higher) than the anticorrosion potential, and corrosion occurs.
Further, the anode generated current tends to be larger at the sacrificial anode 52 closer to the position where the metal object is in contact, and smaller at the farther away from the other metal contact metal object.

(Influence of interference by stray current under cathodic protection)
If the substructure 1 is in soil with stray currents flowing, some of the stray currents may flow into parts of the substructure 1 and out of other locations of the substructure 1 . In the substructure 1 into which the stray current flows, the ground potential is on the negative side, and this stray current also provides an anticorrosion effect. Occur.
On the other hand, the anode generated current decreases in the range where the stray current flows into the base structure 1, and conversely, the anode generated current increases in the range where the stray current flows out to the base structure 1. In particular, if a stray current flows out from the sacrificial anode 52, there is a danger that the sacrificial anode 52 will rapidly wear out due to the excessive current, and will be worn out before the planned service life is reached.

(Monitoring system)
FIG. 2 is a diagram showing an example of a monitoring system according to an embodiment of the invention.
The monitoring system 200 detects that the steel foundation beams 33 of the substructure 1 do not reach the protection potential, even though they are cathodic protected. Furthermore, the monitoring system 200 identifies the reasons why the steel foundation beams 33 of the foundation structure 1 do not reach the corrosion protection potential. In this embodiment, as an example, the case where it is detected that the steel foundation beams 33 of the foundation structure 1 do not reach the anticorrosive potential for each foundation floor slab including four foundation structures 1 will be described. However, the number of foundation structures 1 included in the foundation slab is not limited to four. For example, a foundation deck may include one to three foundation structures 1, or may include five or more foundation structures 1.
The monitoring system 200 monitors the foundation beams of a plurality of foundation structures among the foundation structure 1a-11, the foundation structure 1b-11, the foundation structure 1c-11, and the foundation structure 1d-11 included in the foundation floor slab B11. Measure ground potential. Here, the base slab is a member that directly receives a load.
The base section 30 of the base structure 1a-11 and the base section 30 of the base structure 1b-11 share a steel base beam 33ab-11. The base section 30 of the base structure 1b-11 and the base section 30 of the base structure 1d-11 share a steel base beam 33bd-11. The foundation section 30 of the foundation structure 1d-11 and the foundation section 30 of the foundation structure 1c-11 share a steel foundation beam 33dc-11. The base section 30 of the base structure 1c-11 and the base section 30 of the base structure 1a-11 share a steel base beam 33ca-11.
Hereinafter, any of the foundation beams 33ab-mn, 33bc-mn, 33ca-mn, and 33bd-mn will be referred to as the foundation beam 33.

In the example shown in FIG. 2, to measure the ground potential of the foundation beam 33, the potential measuring machine 60a-11 uses a reference electrode 71a-11 and a steel foundation beam of the foundation 30 of the foundation structure 1a-11. 33 via an electric wire. A potential measuring machine for measuring ground potential is installed on each floor slab of a plurality of foundation structures. Potential measuring device 60 a - 11 is connected to monitoring device 100 via network 50 . Also, the steel base beam 33 of the base portion 30 of the base structure 1a-11 is connected via the switch SW-11.
The ground potential of the foundation beam 33 is based on the reference electrode 71a-11 of the coupon 72a-11 simulating the steel exposed surface of the coating film defect portion of the steel foundation beam 33 (hereinafter referred to as the “coating film defect portion”). measured as ground potential. Coupons are small pieces of steel having the same composition as the steel base beams and having a known surface area.

A zinc reference electrode is generally used as the reference electrode 71a-11 that can be buried in the ground and used permanently. Therefore, the zinc reference electrode is used for measuring the ground potential of steel foundation beams. . The zinc reference electrode is made by covering a zinc alloy with a backfill whose main component is bentonite.
A reference electrode 71a-11 is placed in close proximity to the coupon 72a-11. The reason is that when there is a distance from the coupon 72a-11 to the reference electrode 71a-11, the voltage drop (IR drop) in the soil caused by the anticorrosive current flowing in the soil is This is because the coupon 72a-11 is judged to have apparently reached the corrosion-protective potential even if it has not reached the corrosion-protective potential because it is added to the minus side.
In addition to the method in which the reference electrode 71a-11 is brought close to the coupon 72a-11, the switch SW-11 cuts off the anti-corrosion current flowing into the coupon 72a-11, and the ground potential to the coupon 72a-11 at that moment. is measured by the reference electrode 71a-11, the IR drop is further suppressed.
The ground potential of the coupon when the coupon is not turned off is called the coupon-on potential, and the ground potential of the coupon when the coupon is turned off is called the coupon-off potential.
A voltmeter, a high-sensitivity recorder, a digital multimeter, a data logger, or the like is used as the potential measuring device 60a-11. For the connection of electric wires to the potential measuring device 60a-11, the reference electrode 71a-11 side is normally the negative pole, and the coupon 72a-11 is the positive pole.
The potential measuring device 60a-11 simulates the ground potential of the coating film defect of the steel foundation beam 33 of the base part 30 based on the reference electrode 71a-11, and simulates the coating film defect of the steel foundation beam 33. Ground potential measurement information is created by measuring the ground potential of the coupon 72-a11 and creating ground potential measurement information including information indicating the ground potential measurement result, identification information of the foundation beam 33, and measurement time information. is sent to the monitoring device 100 .

Also, in order to measure the current generated in the current supply 51a-11, a current measuring device 70a-11 measures the current supply 51a-11 and the steel foundation beam 33 of the base 30 of the substructure 1a-11. connected with Current measuring device 70 a - 11 is connected to monitoring device 100 via network 50 . The current generated by the current supply section 51a-11 is measured by a current measuring device 70a-11 inserted between the current supply section 51a-11 and the steel foundation beam 33 of the foundation structure 1a-11. As the current measuring device 70a-11, an ammeter, a combination of a current shunt and a high-sensitivity recorder, or a digital multimeter or data logger is used. If the magnitude of the generated current is greater than the design value, on the premise that the steel foundation beam 33 maintains the anti-corrosion potential, the design value is adjusted by a variable resistor or fixed resistor inserted in series in the current circuit. Suppress the generated current so that it is within
Since one or more electric current supply units 51a-11 are installed on one floor, anti-corrosion monitoring for steel foundation beams is installed on each floor. An ammeter measuring the anticorrosion current is installed on each floor slab of a plurality of substructures. The reference electrode 71a-11 and the coupon 72a-11 are embedded close to the far end from the magnesium alloy anode where the anti-corrosion current from the magnesium alloy anode does not easily flow.
Lead wires from the magnesium alloy anode, the reference electrode 71a-11, and the coupon 72a-11 are raised on the floor slab and connected to a terminal block provided on the erection pole. Protect the lead wire from the ground to the terminal block with a wire protection tube to prevent disconnection or damage. Switches and resistors are placed on the terminal block to cut off the anti-corrosion current and adjust the current value. As a result, if you bring in a measuring instrument when you want to measure at all points, the terminal block installed on the erection pole will generate the ground potential (coupon-on potential and coupon-off potential) and anode of the steel foundation beam. It is possible to measure the current generated by the magnesium alloy anode, which is the anticorrosion current. In addition, continuous measurement is possible by installing a data logger as necessary. Furthermore, if the network 50 and the monitoring device 100 are added, remote monitoring becomes possible.
The current measuring device 70a-11 measures the current generated from the current supply part 51a-11 and flowing into the foundation part 30 including the foundation beam 33 and the pile reinforcing bars connected thereto, and measures the current measurement result and the foundation beam 33 identification information and measurement time information is created, and the created current measurement information is transmitted to the monitoring device 100 .

In addition, the monitoring system 200 includes a foundation structure 1a-mn (m and n are integers of m>1 and n>1), a foundation structure 1b-mn, and a foundation structure 1c-mn included in the foundation slab Bmn. , the ground potential of a plurality of foundation beams among the foundation structures 1d-mn.
FIG. 3 is a diagram showing an example of a base slab. As shown in FIG. 3, the foundations 30 of the substructures 1a-mn and the foundations 30 of the substructures 1b-mn share steel foundation beams 33ab-mn. The base section 30 of the base structure 1b-mn and the base section 30 of the base structure 1d-mn share a steel base beam 33bd-mn. The foundation section 30 of foundation structure 1d-mn and the foundation section 30 of foundation structure 1c-mn share a steel foundation beam 33dc-mn. The foundation sections 30 of the foundation structures 1c-mn and the foundation sections 30 of the foundation structures 1a-mn share a steel foundation beam 33ca-11. Returning to FIG. 2, the description is continued. In the example shown in FIG. 2, to measure the ground potential of the foundation beams 33, the potential measuring machines 60a-mn use reference electrodes 71a-mn and the steel foundation beams of the foundations 30 of the substructures 1a-mn. 33 (foundation beams 33ab-mn, foundation beams 33ca-mn) through electrical wires. Potential measuring machines 60 a - mn are connected to monitoring device 100 via network 50 . Also, the steel foundation beams 33 (foundation beams 33ab-mn, foundation beams 33ca-mn) of the foundations 30 of the foundation structures 1a-mn and the coupons 72a-mn are connected via switches SW-mn. .

The potential measuring devices 60a-mn measure the potentials of the coupons 72a-mn with respect to the soil with reference to the reference electrodes 71a-mn, and provide information indicating the measurement results of the ground potentials of the foundation beams 33, identification information of the foundation beams 33, and , and the measurement time information, and outputs the created ground potential measurement information to the monitoring device 100 .
Also, in order to measure the current generated in the current supplies 51a-mn, current measuring machines 70a-mn measure the current supplies 51a-mn and the steel foundation beams 33 of the bases 30 of the substructures 1a-11. connected with Current measuring machines 70 a - mn are connected to monitoring device 100 via network 50 .
The current measuring devices 70a-mn measure currents generated from the current supply units 51a-mn and flowing into the foundation portion 30 including the foundation beams 33 and the pile reinforcing bars connected thereto. Ground potential measurement information including identification information of the beam 33 and measurement time information is created, and the created ground potential measurement information is output to the monitoring device 100 .

The monitoring device 100 uses ground potential measurement information output by each of the potential measuring devices 60a-11 to 60a-mn and current measurement information output by each of the current measuring devices 70a-11 to 70a-mn. and receive. Based on the received ground potential measurement information and current measurement information, the monitoring device 100 determines whether or not a low-grounding object is in contact with the steel foundation beam 33 of the foundation portion 30, and detects interference of the stray current. determination of whether or not current outflow has occurred, or both.

An arbitrary base slab among the base slabs B11 to Bmn is hereinafter referred to as a base slab Bmn. Further, an arbitrary basic structure among the basic structures 1a-11 to 1a-mn is described as a basic structure 1a-mn, and an arbitrary basic structure among the basic structures 1b-11 to 1b-mn is the basic structure 1b -mn, an arbitrary basic structure among the basic structures 1c-11 to 1c-mn is denoted as the basic structure 1c-mn, and any basic structure among the basic structures 1d-11 to 1d-mn are described as substructures 1d-mn.
An arbitrary current supply unit among the current supply units 51a-11 to 51a-mn is referred to as a current supply unit 51a-mn, and an arbitrary current supply unit among the potential measurement devices 60a-11 to 60a-mn The potential measuring machines are described as potential measuring machines 60a-mn. Further, an arbitrary potential measuring machine among the potential measuring machines 60a-11 to 60a-mn is referred to as a potential measuring machine 60a-mn, and any of the current measuring machines 70a-11 to 70a-mn is described as a potential measuring machine. The current measuring machines are described as current measuring machines 70a-mn. An arbitrary reference electrode among the reference electrodes 71a-11 to 71a-mn is referred to as a reference electrode 71a-mn. An arbitrary coupon among the coupons 72a-11 to 72a-mn is referred to as a coupon 72a-mn.

Of the potential measuring devices 60a-11 to 60a-mn, the current measuring devices 70a-11 to 70a-mn, and the monitoring device 100 included in the monitoring system 200, the monitoring device 100 will be described below. do.
(monitoring device 100)
FIG. 4 is a block diagram showing a monitoring device that constitutes the monitoring system according to the embodiment of the present invention.
The monitoring device 100 is implemented by a device such as a personal computer, server, or industrial computer.
The monitoring device 100 includes a communication unit 110, a storage unit 120, an information processing unit 130, and bus lines such as an address bus and a data bus for electrically connecting each component as shown in FIG. 160.

Communication unit 110 is implemented by a communication module. The communication unit 110 communicates via the network 50 with external devices such as the potential measuring devices 60a-11 to 60a-mn and the current measuring devices 70a-11 to 70a-mn. Specifically, communication unit 110 receives ground potential measurement information transmitted from potential measuring devices 60a-11 to 60a-mn, and outputs the received ground potential measurement information to information processing unit 130. . Communication unit 110 also receives current measurement information transmitted from each of current measuring devices 70a-11 to 70a-mn, and outputs the received current measurement information to information processing unit .

The storage unit 120 is implemented by, for example, a RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), flash memory, or a hybrid storage device in which a plurality of these are combined. Some or all of the storage unit 120 can be accessed via the network 50 by the processor of the monitoring device 100, such as a NAS (Network Attached Storage) or an external storage server, instead of being provided as part of the monitoring system 200. may be implemented by any external device. The storage unit 120 stores a program 122 executed by the information processing unit 130, an application 124, a simulation result 126, and foundation beam position information 128.

The application 124 causes the monitoring device 100 to receive ground potential measurement information transmitted from each of the potential measuring devices 60a-11 to 60a-mn.
App 124 causes monitoring device 100 to receive the current measurement information transmitted by each of current measuring devices 70a-11 through 70a-mn.
The application 124 causes the monitoring device 100 to accept the received multiple pieces of ground potential measurement information and the multiple pieces of current measurement information.
The application 124 allows the monitoring device 100 to receive a plurality of pieces of ground potential measurement information and a plurality of pieces of current measurement information, and attaches other metal objects (low-ground Determine whether or not there is a point where objects are in contact with each other.
The application 124 causes the monitoring device 100 to specify the location when it determines that there is a location where another metal object is in contact with all the steel materials that are electrically connected to the steel foundation beam 33 .
The application 124 causes the monitoring device 100 to determine whether current outflow due to interference of stray current from electric railways or the like is occurring based on the received ground potential measurement information and current measurement information.
The application 124 causes the monitoring device 100 to specify the location when it determines that current outflow is occurring due to interference of stray current from an electric railway or the like.

The simulation result 126 is the simulation result of the case where there is no contact with other metal objects (low-grounding objects) on all the steel materials that are in contact with the steel foundation beam, and the stray current from electric railways and the like. It stores the simulation results of the case where current outflow due to interference does not occur and the case where current outflow due to interference occurs. Here, an example of the simulation results for the case where there is no contact with other metal objects on all the steel materials that are in contact with the steel foundation beam is shown below. Fig. 10 is the result of simulating the potential using a plurality of reference electrodes when applied. Details thereof will be described later. An example of the simulation results for the case where there is no current outflow due to interference of stray currents from electric railways, etc. and the case where current outflow due to interference occurs , is the result of simulating the potential measurement value by changing the direction of the stray current. Details thereof will be described later.
The foundation beam position information 128 is table format information that associates the identification information of the foundation beam with the position information of the foundation beam.

The information processing unit 130 is a functional unit (hereinafter referred to as “software functional unit”) realized by executing a program 122 or an application 124 stored in the storage unit 120 by a processor such as a CPU (Central Processing Unit). is. Note that all or part of the information processing unit 130 may be realized by hardware such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), or FPGA (Field-Programmable Gate Array). It may be realized by a combination of units and hardware.
The information processing unit 130 includes, for example, a reception unit 131, a processing unit 132, and an identification unit 133.

The reception unit 131 acquires a plurality of pieces of ground potential measurement information output by the communication unit 110, and receives the acquired plurality of pieces of ground potential measurement information. Further, the reception unit 131 acquires a plurality of pieces of current measurement information output by the communication unit 110, and receives the acquired plurality of pieces of current measurement information. The receiving unit 131 outputs the received plurality of ground potential measurement information and the plurality of received current measurement information to the processing unit 132 .
The processing unit 132 acquires the plurality of ground potential measurement information and the plurality of current measurement information output by the reception unit 131, and based on the acquired plurality of ground potential measurement information and the current measurement information, the steel It is determined whether or not other metal objects are in contact with all the steel materials electrically connected to the foundation beam 33, and whether or not current outflow is occurring due to interference of stray currents from electric railways or the like.
The ground potential of the steel foundation beam 33 is linked to the fluctuation of the current generated at the anode. Therefore, the phenomenon can be grasped more reliably based on the ground potential and the current generated at the anode. The ground resistance R of the object can be derived based on the variation of the ground potential and the variation of the current generated in the anode. Since the ground resistance R is a function of the soil resistivity ρ and the damaged area A, it can be used as a measure of the size of the contact object. In addition, regarding current outflow due to interference of stray currents, there is a high correlation between the ground potential and the current generated at the anode.
Therefore, in this embodiment, the case of measuring the ground potential and the current generated in the anode will be described. In addition, the current generated in the anode is also used to check the service life, as it affects the consumption of the anode.
Specifically, when other metal objects are in contact with all the steel materials that are electrically connected to the steel foundation beam 33, the current supply unit 51 supplies the steel foundation beam 33 of the foundation portion 30 with anti-corrosion current. The electric current increases rapidly, and the ground potential of the steel base beam 33 becomes noble. The rapid increase in the anticorrosion current and the nobleness of the ground potential are conspicuous at the contact point.

On the other hand, in the interference of the stray current, the point where the stray current flows into any of the steel foundation, the pile reinforcement 11, the current supply part 51, or a combination of them (hereinafter referred to as "stray current inflow point") ) and a point where a stray current flows out from any of the steel foundation, the pile reinforcing bar 11, the current supply part 51, or a combination thereof (hereinafter referred to as "stray current outflow point"). A stray current inflow point and a stray current outflow point are separated from each other. At the stray current inflow point, the ground potential of the steel base beam 33 becomes base, and the anode-generated current decreases. At the point where the stray current flows, the ground potential of the steel base beam 33 becomes noble, and the anode-generated current increases.
The processing unit 132 acquires information indicating the measurement result of the ground potential included in each of the acquired plurality of ground potential measurement information, and based on each of the acquired information indicating the measurement result of the ground potential, It is determined whether or not the measurement result of has changed by the potential threshold or more.
If none of the plurality of potential measurement results changes by more than the potential threshold, the processing unit 132 determines that none of the steel materials that are electrically connected to the steel foundation beams 33 are in contact with other metal objects, and that the stray current does not occur. It is determined that no current outflow due to interference has occurred.
When at least one of the plurality of potential measurement results changes by a potential threshold or more, the processing unit 132 determines whether or not any of the plurality of potential measurement results has changed to the negative side.
If none of the measurement results of a plurality of potentials have changed to the base side, the processing unit 132 determines that there is a steel material that is electrically connected to the steel base beam 33 and that another metal object is in contact.
The processing unit 132 determines that current outflow due to interference of stray currents is occurring when at least one of the plurality of potential measurement results fluctuates to the negative side.
In addition, the processing unit 132 acquires information indicating current measurement results included in each of the plurality of acquired current measurement information, and based on the acquired information indicating the plurality of current measurement results, the current measurement results are obtained. It is determined whether or not the current has changed by a threshold value or more.
If none of the measurement results of a plurality of currents changes by more than the current threshold, the processing unit 132 determines that none of the steel materials electrically connected to the steel foundation beams 33 are in contact with other metal objects, and that the stray current is It is determined that no current outflow due to interference has occurred.
When at least one of the plurality of current measurement results changes by a current threshold or more, the processing unit 132 determines whether or not there is a decrease in the plurality of current measurement results.
If none of the plurality of current measurement results show a decrease, the processing unit 132 determines that there is another metal object in contact with the steel material electrically connected to the steel base beam 33 .
The processing unit 132 determines that current outflow due to interference of stray currents is occurring when there is a decrease in the measurement results of a plurality of currents.

When the processing unit 132 determines that there is another metal object in contact with the steel material electrically connected to the steel foundation beam 33, the processing unit 132 displays information indicating that contact with a low-grounding object has occurred. Output to unit 150 . When the processing unit 132 determines that contact with the low grounding object has occurred, the processing unit 132 obtains information indicating that the contact with the low grounding object has occurred, identification information of the plurality of steel foundation beams 33, and the steel Low grounded object contact occurrence information including information associated with information indicating the measurement result of the potential measured at the foundation beam 33 of the base beam 33 is created, and the created low grounded object contact occurrence information is output to the specifying unit 133.
When the processing unit 132 determines that current outflow due to interference of stray currents has occurred, the processing unit 132 outputs information indicating that current outflow due to interference of stray currents has occurred to the display unit 150 . When the processing unit 132 determines that the current outflow due to the interference of the stray current has occurred, the processing unit 132 provides information indicating that the current outflow due to the interference of the stray current has occurred, identification information of the plurality of steel foundation beams 33, Stray current generation information including information associated with information indicating the measurement result of the potential measured at the steel foundation beam 33 is created, and the created stray current generation information is output to the specifying unit 133 .

When one or both of the low grounding object contact occurrence information and the stray current occurrence information output by the processing unit 132 are acquired, the specifying unit 133 determines whether the acquired low grounding object contact occurrence information and stray current occurrence information are obtained. and either one or both of, the simulation result 126 stored in the storage unit 120, and the foundation beam position information 128, either the contact point with the low grounding object or the stray current generation point Specify one or both.
Details of the simulation results 126 stored in the storage unit 120 will now be described.
Simulation conditions (numerical analysis conditions) will be described. A section surrounded by girders was designated as the base slab Bmn. A steel base beam was used as the corrosion protection target, and the corrosion protection method was cathodic protection using a sacrificial anode (magnesium alloy). The foundation beams are painted. The sacrificial anode had a dimension Φ of 200 mm×1200 mm and was buried horizontally at a depth of 1.6 m from the ground. In addition, the polarization curve of the beam was made to have an insulation defect rate of 1% of the coating, and the defect rate was applied to the polarization curve of the uncoated steel material (underground). Soil resistance was set to 50 Ωm.
The slope of the potential was 5 mV/m for the stray current. The direction of the stray current was changed and the direction was derived from the potential measurements.
For other metallic contacts, steel contacts were assumed. The contacting steel had a dimension Φ of 100 mm×2000 mm. The contact position was calculated from the potential measurement value by changing the contact position.
Regarding the steel base beam 33, the longitudinal length of the base beam 33ab-mn, the longitudinal length of the base beam 33bd-mn, and the longitudinal length of the base beam 33dc-mn described with reference to FIG. and the length of the base beam 33ca-mn in the longitudinal direction were each set to 10 m.
FIG. 5 shows an example of the dimensions of the foundation beam. As shown in FIG. 5, the flange thickness was 28 mm, the web thickness was 16 mm, the height was 900 mm, and the short side length of the flange was 250 mm.

(Example of simulation results (Part 1))
FIG. 6 shows an example of the installation position of the reference electrode. As shown in FIG. 6, the distance between the reference electrode 2E installed on the base structure 1a-mn and the reference electrode 1E installed on the base structure 1b-mn was set to 9 m. Also, the distance between the reference electrode 1E installed on the basic structure 1b-mn and the reference electrode 4E installed on the basic structure 1d-mn was set to 9 m. Also, the distance between the reference electrode 4E installed on the basic structure 1d-mn and the reference electrode 3E installed on the basic structure 1c-mn was set to 9 m. Also, the distance between the reference electrode 3E installed on the basic structure 1c-mn and the reference electrode 2E installed on the basic structure 1a-mn was set to 9 m. A reference electrode 1E, a reference electrode 2E, a reference electrode 3E, and a reference electrode 4E were installed at a depth of 0.9 m from the ground.

FIG. 7 is a diagram showing an example of simulation results. FIG. 7 shows a case where current outflow due to interference of stray currents does not occur and metal is not in contact with the foundation beam.
7 shows the potentials of the foundation beams 33ab-mn, the foundation beams 33bd-mn, the foundation beams 33dc-mn, the foundation beams 33ca-mn, and the current supply section 51. FIG. The lower diagram (a) of FIG. 7 shows the potential at a depth of 0.9 m from the ground. In both top (a) and bottom (b) of FIG. 7, the protective potential is −0.725 V vs SSE.
According to the upper diagram (a) of FIG. 7, the surface of the base beam is −0.875 V vs SSE, so it can be seen that it is polarized to the base. According to the lower part (b) of FIG. 7, the current supply section 51 is -1.000 V vs SSE, so it can be seen that it is polarized in the negative direction.

FIG. 8 is a diagram showing an example of simulation results. FIG. 8 shows the relationship between the direction of the stray current and the potential distribution. The direction of the stray current will be explained. The origin is the center of the base slab Bmn, and the horizontal line drawn to the right from the origin is 0 degrees. The direction of rotation counterclockwise with respect to this horizontal line is the positive direction.
In FIG. 8, (a) is when there is no stray current, (b) is when the stray current flows in from the direction of 0 degrees, and (c) is when the stray current flows in from the direction of 15 degrees. (d) is the case where the stray current flows in from the direction of 30 degrees, and (e) is the case where the stray current flows in from the direction of 45 degrees. In FIG. 8, the protection potential is −0.725 V vs SSE. According to FIG. 8, it can be seen that the direction in which the stray current flows is negatively polarized by changing the direction in which the stray current flows.

FIG. 9 is a diagram showing an example of simulation results.
FIG. 9 shows, for each of the reference electrodes 1E to 4E described with reference to FIG. is 15 degrees, the direction in which the stray current flows is 30 degrees, and the direction in which the stray current flows is 45 degrees. According to FIG. 9, the reference electrode 1E and the reference electrode 4E are closer to the direction in which the stray current flows than the reference electrode 2E and the reference electrode 3E, so it can be seen that the reference electrode 1E and the reference electrode 4E change to the base side.
Further, based on FIG. 9, the magnitude of the potential gradient and the direction (angle) were derived from the value of the potential of the reference electrode. Table 1 shows the results.

According to Table 1, it can be seen that the angle of the potential gradient derived from the value of the potential of the reference electrode and the direction of the stray current substantially match. Therefore, it can be seen that the direction of the stray current can be derived from the measured value of the potential of the reference electrode.

(Example of simulation results (Part 2))
FIG. 10 shows an example of a metal contact location. The reference electrodes 1E to 4E were installed at a depth of 0.9 m from the ground as described above. The dimension Φ of the contact metal is 100 mm×2000 mm.
In FIG. 10, as shown in (a), a contact metal (steel) CM was buried at a depth of 0.45 m from the ground on the perpendicular bisector between the reference electrodes 1E and 4E. As shown in (b), a contact metal (steel) CM was embedded at a position translated 2 m in the +y direction with respect to (a). As shown in (c), a contact metal (steel) CM was embedded at a position translated 4 m in the +y direction with respect to (a).

FIG. 11 is a diagram showing an example of simulation results. FIG. 11 shows the case of no metal contact, the case of FIG. 10(a), the case of FIG. 10(b), and the case of FIG. 10(c). According to FIG. 11, it can be seen that the ground potential is nobler when the metal is in contact than when there is no metal contact.
FIG. 12 is a diagram showing an example of simulation results. FIG. 12 shows the analysis results when metal is brought into contact. 12 shows the case of no metal contact, the case of FIG. 10(a), and the case of FIG. 10(b) for each of the reference electrodes 1E to 4E described with reference to FIG. , and FIG. 10(c). According to FIG. 12, it can be seen that the base beam can be changed to the noble side by bringing the metal into contact. Moreover, according to FIG. 12, it can be seen that the reference electrodes 1E and 4E are closer to the contact metal than the reference electrodes 2E and 3E, and thus are more noble.
Further, based on FIG. 12, the direction of the gradient of the potential is derived from the value of the reference electrode, and the position (estimated contact position) when the direction of the potential derived from the center of the beam is viewed, that is, the position in the y direction. Derived. Table 2 shows the results.

According to Table 2, it can be seen that the estimated metal contact position derived from the value of the reference electrode is close to the metal contact position. Therefore, it can be seen that the metal contact position can be derived from the potential measurement value of the reference electrode.

(Example of simulation results (Part 3))
FIG. 13 is a diagram showing an example of the base slab.
An example of the simulation result (part 3) is one unit by collecting the above-mentioned examples of the simulation results (parts 1 and 2) and one section of the steel foundation beam (foundation floor slab B11) in 3 × 6 sections. It is different in that Also, the sacrificial anode was buried horizontally at a depth of 1.6 m from the ground at the center of each section.
FIG. 14 shows an example of the installation position of the reference electrode. As shown in FIG. 14, one section (foundation floor slab B11) of a steel foundation beam is collected into 3×6 sections, and a reference electrode 1E is attached to a total of six points including the four corners and the midpoint in the longitudinal direction. ~ A reference electrode 6E was placed.
FIG. 15 is a diagram illustrating an example of simulation results. FIG. 15 shows a case where current outflow due to interference of stray currents does not occur and the foundation beam is not in contact with a low-grounding object.
FIG. 15(a) shows the electric potential of each of the base beams and the current supply section 51 in a collection of 3×6 sections of steel base beams. The lower part (b) of FIG. 15 shows the potential at a depth of 0.9 m from the ground. In both top (a) and bottom (b) of FIG. 15, the protective potential is −0.725 V vs SSE.
According to the upper diagram (a) of FIG. 15, the surface of the base beam is −0.925 V vs SSE, so it can be seen that the base beam is polarized. According to the lower part (b) of FIG. 15, the current supply section 51 is -1.000 V vs SSE, so it is understood that it is polarized to the base. Although 3×6 partitions are shown here, the same applies to arbitrary partitions as well as 3×6 partitions.

FIG. 16 is a diagram illustrating an example of simulation results. FIG. 16 shows the relationship between the direction of the stray current and the potential distribution. A horizontal line drawn to the right from the origin is assumed to be 0 degrees, with the center of a group of 3×6 sections of steel foundation beams collected as the origin. The direction of rotation counterclockwise with respect to this horizontal line is the positive direction.
In FIG. 16, (a) is the case where current outflow due to stray current interference does not occur, (b) is the case where stray current flows in from the direction of 0 degrees, and (c) is the case where stray current is 45 degrees. (d) is the case where the stray current flows in from the direction of 90 degrees. In Figure 16, the protection potential is -0.750 V vs SSE. According to FIG. 16, it can be seen that the direction in which the stray current flows is negatively polarized by changing the direction in which the stray current flows. Although 3×6 partitions are shown here, the same applies to arbitrary partitions as well as 3×6 partitions.
FIG. 17 is a diagram illustrating an example of simulation results. FIG. 17 shows the analysis results of stray currents. FIG. 17 shows, for each of the reference electrodes 1E to 6E described with reference to FIG. 14, a case where current outflow due to interference of stray current does not occur, and a case where the direction in which the stray current flows is 0 degrees. , the results of deriving the potential are shown for the case where the direction of the stray current is 45 degrees and the case where the direction of the stray current is 90 degrees. According to FIG. 17, as the direction in which the stray current flows changes from 0 degrees to 90 degrees, the reference electrode 5E, the reference electrode 6E, and the reference electrode 3E, which are closer to the direction in which the stray current flows, change to the negative side in order. I know you are.
Also, based on FIG. 17, the magnitude and angle of the potential gradient were derived from the value of the reference electrode. Table 3 shows the results.

According to Table 3, it can be seen that the angle derived from the reference electrode value is close to the angle at which the stray current flows. Therefore, it can be seen that the direction (angle) in which the stray current flows can be derived from the measured value of the potential of the reference electrode. In other words, it is possible to derive the position of the floor slab where current outflow occurs due to interference of stray currents.

(Example of simulation results (Part 4))
FIG. 18 shows an example of a metal contact location. The reference electrodes 1E to 6E were installed at a depth of 0.9 m from the ground as described above. The dimension Φ of the contact metal CM is 100 mm×2000 mm.
In FIG. 18, a contact metal (steel) CM was embedded at a depth of 0.45 m from the ground by moving parallel 4 m in the y-axis direction from the perpendicular bisector of the reference electrode 6E and the reference electrode 4E.
FIG. 19 is a diagram illustrating an example of simulation results. FIG. 19 shows the case without metal contact and the case of FIG. According to FIG. 19, it can be seen that the ground potential is nobler when metal is in contact than when there is no metal contact.
FIG. 20 is a diagram showing an example of simulation results. FIG. 20 shows the analysis results when metal is brought into contact. FIG. 20 shows potentials for each of the reference electrodes 1E to 6E described with reference to FIG. 14 when there is no metal contact and when there is metal contact. According to FIG. 20, it can be seen that the base beam can be changed to the noble side by bringing the metal into contact.
Based on FIG. 20, the direction of the gradient of the potential was derived from the value of the reference electrode, and the position when the direction of the potential derived from the center of the beam, that is, the position in the y direction was derived. The result was 1.2 m, which was close to the estimated metal contact position derived from the potential value of the reference electrode. Therefore, it can be seen that the metal contact position can be derived from the measured value of the potential of the reference electrode. In other words, it is possible to derive the position of the floor slab where the low-grounding object is in contact with the foundation.

Returning to FIG. 4, the description is continued. The identification unit 133 associates the identification information of the plurality of steel foundation beams 33 included in the acquired low grounding object contact occurrence information with the information indicating the measurement result of the potential measured at the steel foundation beams 33. get the information The identification unit 133 selects from the foundation beam position information 128 of the storage unit 120 based on each of the acquired identification information of the plurality of steel foundation beams 33 the foundation beam associated with the identification information of each steel foundation beam 33. Get the location information of . The specifying unit 133 derives the position of the floor slab in contact with the low-grounding object based on each of the acquired position information of the plurality of foundation beams and the measurement result of the ground potential measured at the foundation beam. . In addition, the identifying unit 133 compares each of the acquired position information of the plurality of foundation beams and the measurement result of the ground potential measured at the foundation beam with the simulation result to determine the position where the low-grounding object is in contact. to derive Specifically, the identifying unit 133 compares each of the acquired position information of the plurality of foundation beams with the measurement result of the ground potential measured at the foundation beam with FIG. Among case 1, case 2, and case 3, the floor slab with the most similar potential is selected, and the position where the grounded object is in contact is derived from the selected floor slab.
Further, the identifying unit 133 obtains each of the position information of at least three foundation beams and the foundation beam from each of the obtained position information of the plurality of foundation beams and the measurement result of the ground potential measured at the foundation beam. Acquire the measurement result of the ground potential measured at the beam. The specifying unit 133 derives a potential gradient based on each of the acquired position information of the at least three foundation beams and the measurement result of the ground potential measured at the foundation beam, and the direction from the derived potential gradient to derive Based on the derived potential gradient, the identifying unit 133 derives the position of the foundation beam when viewed from the center of the foundation slab Bmn in the direction of the potential gradient, thereby deriving the position at which the low-grounding object is in contact. . The identifying unit 133 outputs to the display unit 150 the derived information indicating the contact position of the low-grounding object.

Further, the identifying unit 133 associates the identification information of the plurality of steel foundation beams 33 included in the acquired stray current generation information with the information indicating the measurement result of the potential measured at the steel foundation beams 33. get the information The identification unit 133 selects from the foundation beam position information 128 of the storage unit 120 based on each of the acquired identification information of the plurality of steel foundation beams 33 the foundation beam associated with the identification information of each steel foundation beam 33. Get the location information of . The specifying unit 133 identifies the position of the floor slab where the current outflow due to the interference of the stray current occurs based on each of the acquired position information of the plurality of foundation beams and the measurement result of the potential measured at the foundation beam. derive In addition, the specifying unit 133 derives the direction of the stray current by comparing each of the acquired position information of the plurality of foundation beams and the measurement result of the potential measured at the foundation beam with the simulation result. Specifically, the identification unit 133 compares each of the acquired position information of the plurality of foundation beams with the measurement result of the ground potential measured at the foundation beam with FIG. 9 to determine that there is no stray current. , 0, 15, 30, and 45 degrees, the floor slab with the most similar potential is selected, and the direction of the stray current is derived from the selected floor slab.
Further, the identifying unit 133 obtains each of the position information of at least three foundation beams and the foundation beam from each of the obtained position information of the plurality of foundation beams and the measurement result of the ground potential measured at the foundation beam. Acquire the measurement result of the ground potential measured at the beam. The specifying unit 133 derives a potential gradient based on each of the obtained positional information of the at least three foundation beams and the measurement result of the ground potential measured at the foundation beam, and from the derived potential gradient Derive its direction. The specifying unit 133 derives the angle of the stray current by deriving the angle when the direction of the potential gradient is viewed from the center of the base slab Bmn based on the derived gradient of the potential. The specifying unit 133 outputs to the display unit 150 information indicating the position into which the derived stray current has flowed.

Here, the process of detecting the metal contact point by the magnesium alloy anode-generated current and the current outflow point by the interference of the stray current will be described.
FIG. 21 is a diagram showing an example of a steel foundation beam.
A process of detecting a metallic object contact position by the identifying unit 133 will be described. In order to measure the current generated by the magnesium alloy anode, a current measuring device is inserted between the magnesium alloy anode, the steel foundation beam, and the erecting pole with continuity, and a current measuring device is prepared for each section of the steel foundation beam. do. A current measuring device is installed on each floor slab of the plurality of substructures to measure the protection current. By configuring in this way, it is possible to constantly monitor the current generated by the magnesium alloy anode in all the sections. As shown in FIG. 21, the positions of the steel foundation beams are set so that the horizontal direction of the compartment is the 1st row, the 2nd row, . Let the directions be the 1st row, the 2nd row, . FIG. 21 shows 15 sections of 5 columns×3 rows as an example. In this case, a current measuring device is installed on the floor slab contained in each of the 15 compartments.
If another metal object were to come into contact with the 1 column×1 row steel foundation beam, the current generated by the magnesium alloy anode would change with the passage of time.

FIG. 22 is a diagram showing an example of temporal changes in magnesium alloy anode-generated current during contact with a metal object.
If there is no metal contact, the anti-corrosion current is assumed to be almost constant regardless of the position of the steel foundation beam. When a metal object comes into contact with the steel foundation beam in this steady state, the current generated from the magnesium alloy anode also flows into the contacting metal contact portion. Therefore, the generated current of the magnesium alloy anode greatly increases from the steady state when the metallic object contacts. The degree of increase in the current generated by the magnesium alloy anode is greater for the magnesium alloy anode closer to the metal contact portion with the steel foundation beam, and smaller for the magnesium alloy anode farther from the metal contact portion.
For this reason, the magnitude of the current generated by the magnesium alloy when a metal object contacts the central part of the steel foundation beam in the third row and the second row is When the current to be applied is represented by "In, m", it is as follows.
I3,2>I3,1, I3,3, I2,2, I4,2>I2,1, I4,1, I2,3, I4,3
Therefore, if the current generated by the magnesium alloy anode can be constantly monitored, the contact position of the metal object can be estimated from the magnitude of the current generated by the magnesium alloy anode. The identification unit 133 derives a floor slab in which a low-grounding object is in contact with the base based on the magnitude of the current generated by the magnesium alloy anode.
The generated current of the magnesium alloy anode does not need to be constantly monitored by a communication line, and even by periodically measuring the current generated by the magnesium alloy anode, the contact point of the metal object can be determined from the magnitude of the current generated by the magnesium alloy anode. can be estimated.
In addition, even if the current generated by the magnesium alloy anode is measured by skipping several adjacent magnesium alloy anodes instead of measuring it at all points, it is possible to roughly grasp the contact points of the metal objects.

Next, a process of detecting a current outflow range due to interference of stray currents by the identifying unit 133 will be described.
If there are many steel foundation beams where the stray current leaking from the rails is flowing into the soil, the stray current flowing through the soil should take the route that minimizes the voltage drop. Therefore, it flows into pile reinforcing bars with low ground resistance, paint film defects of steel foundation beams, and magnesium alloy anodes. The stray current that once flowed into the defective coating of the pile reinforcing bars and steel foundation beams and the magnesium alloy anode flows out into the soil from another location, such as the defective coating of the pile reinforcing bars and steel foundation beams and the magnesium alloy anode. and then return to the rails of the DC electric railway.
FIG. 23 is a diagram showing an example of a time-dependent change in the generated current of the magnesium alloy anode at the outflow location of the stray current.
The stray current leaked from the DC electric railway is applied to the defective coating film of the steel foundation beams, the pile reinforcing bars, and the magnesium alloy anodes of the steel foundation beams shown in FIG. Let us consider a case in which the air flows in, flows out from column 5, row 1 to column 5, row 3, and returns to the rails of the DC electric railway. In the 1st row to 1st row 3 row where the stray current flowed, the potential of the defective coating of the steel foundation beam, the pile reinforcement, and the magnesium alloy anode shifted to the base side, and the generated current of the magnesium alloy anode It decreases compared to before the stray current entered.
On the other hand, if the stray current flows out from the coating film defects of the pile reinforcing bars and steel foundation beams or from the magnesium alloy anode, etc., the coating film defects of the pile reinforcing bars and steel foundation beams in columns 5, 1, 5, 3, etc. As the potential of the part and the magnesium alloy anode becomes nobler, the generated current of the magnesium alloy anode increases compared to before the stray current flows out. Corrosion occurs at defective coating film parts of steel foundation beams and steel foundation beams, where stray currents flow into the soil, and at magnesium alloy anodes. Since the magnesium alloy anode is forced to melt, the life of the anode is shortened.
The range of current outflow due to interference of stray current is where the generated current of the magnesium alloy anode increases. The specifying unit 133 derives the position of the floor slab where the current outflow due to the interference of the stray current occurs, based on the current generated by the magnesium alloy anode. Returning to FIG. 4, the description is continued.

The operation unit 140 is an input device that receives user operations, and includes a pointing device such as a touch panel, buttons, dials, a touch sensor, a touch pad, and the like.
The display unit 150 is configured by, for example, a liquid crystal display. The display unit 150 displays the information output by the processing unit 132 indicating that the low grounding object is in contact, the information output by the identifying unit 133 indicating the position where the low grounding object is in contact, and the stray current output by the processing unit 132. Information indicating that the stray current is occurring, information indicating the position where the stray current output by the specifying unit 133 is occurring, and the like are displayed.

(Operation of monitoring system)
24 and 25 are flowcharts showing an example of the operation of the monitoring system of this embodiment. 24 and 25 mainly show the operation of the monitoring device 100 included in the monitoring system 200. FIG.
Ground potential fluctuates due to current flowing in and out of the object. The current changes immediately with the occurrence of deformation, but the ground potential is often accompanied by the polarization of the object, and the potential change accompanying the occurrence of deformation is slower than the current. From the above, in this embodiment, in addition to the steel member ground potential, both the anode-generated current is monitored to detect the presence or absence of contact with other metals and the presence or absence of stray current interference (outflow area is a corroded area). I will continue to explain the case where
Referring to FIG. 24, reference electrodes (71a-mn) connect coupons 72a-11 connected via electric wires to steel foundation beams 33 of foundations 30 of foundation structures (1a-11 to 1a-mn) to reference electrodes (71a-mn). 11 to 71a-mn), and based on the measurement results, it is determined whether or not a low-grounding object is in contact with the foundation beam 33, and whether or not current outflow is occurring due to interference of stray currents. Processing for performing either one or both of determination will be described.

Each of the potential measuring machines 60a-11 to 60a-mn is a coupon 72a- connected via electric wire to the steel foundation beam 33 of the base portion 30 of the foundation structure (1a-11 to 1a-mn). 11 is measured with reference electrodes (71a-11 to 71a-mn) to create ground potential measurement information including information indicating the measurement result of the ground potential, identification information of the foundation beam 33, and measurement time information. and transmits the created ground potential measurement information to the monitoring device 100 .
(Step S1)
The communication unit 110 of the monitoring device 100 receives the ground potential measurement information transmitted from each of the potential measuring devices 60a-11 to 60a-mn, and outputs the received ground potential measurement information to the information processing unit 130. .
The reception unit 131 of the information processing unit 130 acquires a plurality of pieces of ground potential measurement information output from the communication unit 110 and accepts the acquired plurality of pieces of ground potential measurement information.

(Step S2)
The processing unit 132 acquires a plurality of pieces of ground potential measurement information output by the reception unit 131, and acquires information indicating ground potential measurement results included in each of the acquired plurality of pieces of ground potential measurement information. The processing unit 132 determines whether or not there is a change of the potential measurement result equal to or more than the potential threshold based on each of the obtained pieces of information indicating the measurement results of the ground potential.
(Step S3)
If none of the plurality of potential measurement results change by more than the potential threshold, the processing unit 132 determines that none of the steel materials electrically connected to the steel foundation beams 33 are in contact with other metal objects, and the stray current is not generated. It is determined that no current outflow due to interference has occurred.
(Step S4)
When at least one of the plurality of potential measurement results changes by a potential threshold or more, the processing unit 132 determines whether or not any of the plurality of potential measurement results has changed to the negative side.

(Step S5)
The processing unit 132 determines that a low-grounding object is in contact with the foundation beam 33 when none of the measurement results of the plurality of ground potentials fluctuates to the base side. When the processing unit 132 determines that the low-grounding object is in contact with the foundation beam 33 , the processing unit 132 outputs information indicating that the low-grounding object is in contact with the foundation beam 33 to the display unit 150 . When the processing unit 132 determines that the low grounding object is in contact with the foundation beam 33, the processing unit 132 provides information indicating that the low grounding object is in contact with the foundation beam 33 and identification information of the steel foundation beam 33. and information indicating the measurement result of the ground potential are created, and the created low grounded object contact occurrence information is output to the identifying unit 133 .
(Step S6)
The identifying unit 133 acquires information that associates the identification information of the steel foundation beam 33 included in the acquired low grounded object contact occurrence information with the information indicating the measurement result of the ground potential. The identification unit 133 derives the position of the floor slab contacted by the low-grounding object based on information that associates the acquired identification information of the steel foundation beam 33 with the information indicating the measurement result of the ground potential. The identification unit 133 derives the position where the low-grounding object is in contact based on the information that associates the acquired identification information of the steel foundation beam 33 with the information indicating the measurement result of the ground potential. The specifying unit 133 outputs to the display unit 150 the derived information indicating the contact position of the low-grounding object.
If a low-grounding object comes into contact, the potential of the foundation beam 33 will rise. In this case, the potential of the foundation beam 33 can be lowered by removing the low grounding object based on the contact position of the low grounding object.

(Step S7)
The processing unit 132 determines that a current outflow has occurred due to interference of stray currents when there is a change in the base side among the plurality of ground potential measurement results. When the processing unit 132 determines that current outflow due to interference of stray currents has occurred, the processing unit 132 outputs information indicating that current outflow due to interference of stray currents has occurred to the display unit 150 . If the processing unit 132 determines that the current outflow has occurred due to the interference of the stray current, the processing unit 132 provides information indicating that the current outflow has occurred due to the interference of the stray current, the identification information of the steel foundation beam 33, and the ground potential. and the information associated with the information indicating the measurement result of .
(Step S8)
The identifying unit 133 acquires the current outflow occurrence information due to the interference of the stray current output by the processing unit 132, and the identification information of the steel foundation beam 33 included in the acquired current outflow occurrence information due to the interference of the stray current. Information associated with the information indicating the potential measurement result is acquired. The identification unit 133 derives the position of the floor slab where current outflow due to interference of stray currents has occurred based on the obtained identification information of the steel foundation beam 33 and information indicating the measurement result of the ground potential. Based on the obtained identification information of the steel foundation beam 33 and the information indicating the measurement result of the ground potential, the identifying unit 133 determines that the current outflow due to the interference of the stray current is detected from the ground potential measurement result. Derive the location where it occurred. The specifying unit 133 outputs to the display unit 150 information indicating the location where the current outflow due to the interference of the derived stray current has occurred.
When current outflow occurs due to interference of stray currents, corrosion is a problem because a large amount of current flows out from a portion with a high potential. In this case, the current can be lowered by inserting a resistor in the magnesium electrode circuit. If the potential does not decrease even if a resistance is inserted into the magnesium electrode circuit, the potential can be decreased by adding magnesium.

Referring to FIG. 25, measurement results of the current flowing from the current supply units (51a-11 to 51a-mn) to the steel foundation beams 33 of the foundation portion 30 of the foundation structure and to the pile reinforcing bars that are electrically connected to them. Based on, a description will be given of the processing of determining whether or not a low-grounding object is in contact with the foundation beam 33 and determining whether or not current outflow due to interference of stray currents has occurred, or both. do.
Each of the current measuring devices 70a-11 through 70a-mn is connected from a current supply (51a-11 through 51a-mn) to the steel foundation beam 33 of the base portion 30 of the foundation structure as well as to it. measuring the current flowing through the pile reinforcement, creating current measurement information including information indicating the current measurement result, identification information of the foundation beam 33, and measurement time information, and sending the created current measurement information to the monitoring device Send to 100.
(Step S11)
The communication unit 110 of the monitoring device 100 receives current measurement information transmitted from each of the current measuring devices 70a-11 to 70a-mn, and outputs the received current measurement information to the information processing unit .
The receiving unit 131 of the information processing unit 130 outputs the received plurality of pieces of current measurement information to the processing unit 132 .
(Step S12)
The processing unit 132 acquires a plurality of pieces of current measurement information output by the reception unit 131, and acquires information indicating current measurement results included in each of the acquired plurality of pieces of current measurement information. The processing unit 132 determines whether or not there is a current measurement result that has changed by a current threshold value or more, based on each of the acquired pieces of information indicating the plurality of current measurement results.
(Step S13)
If all of the measurement results of a plurality of currents do not change by more than the current threshold, the processing unit 132 determines that none of the steel materials electrically connected to the steel foundation beams 33 are in contact with other metal objects, and that the stray current is It is determined that current outflow due to interference has not occurred.
(Step S14)
When at least one of the plurality of current measurement results changes by a current threshold or more, the processing unit 132 determines whether or not there is a decrease in the plurality of current measurement results.
(Step S15)
The processing unit 132 determines that a low-grounding object is in contact with the foundation beam 33 when none of the plurality of measurement results of the current has decreased. When the processing unit 132 determines that the low-grounding object is in contact with the foundation beam 33 , the processing unit 132 outputs information indicating that the low-grounding object is in contact with the foundation beam 33 to the display unit 150 . Here, the specifying unit 133 may derive the position of the floor slab where the foundation beam 33 is in contact with the low-grounding object, based on the results of measuring a plurality of currents.

(Step S16)
The processing unit 132 determines that an outflow of current has occurred due to interference of stray currents when there is a decrease in the measurement results of a plurality of currents. The processing unit 132 outputs to the display unit 150 information indicating that a stray current has occurred when determining that current outflow has occurred due to interference of stray currents. Here, the specifying unit 133 may derive the position of the floor slab where current outflow due to interference of stray currents has occurred, based on a plurality of current measurement results.
After step S15, the processing unit 132 associates the information indicating that the foundation beam 33 is in contact with a low-grounding object, the identification information of the steel foundation beam 33, and the information indicating the ground potential measurement result. Low-grounded object contact occurrence information including the information may be created, and the created low-grounded object contact occurrence information may be output to the specifying unit 133 .
The identifying unit 133 acquires information that associates the identification information of the steel foundation beam 33 included in the acquired low-grounded object contact occurrence information with the information indicating the ground potential measurement result. The identification unit 133 derives the position at which the low-grounding object is in contact based on the obtained identification information of the steel foundation beam 33 and the information that associates the information indicating the measurement result of the ground potential. The identifying unit 133 outputs to the display unit 150 the derived information indicating the contact position of the low-grounding object.
If a low-grounding object comes into contact, the potential of the foundation beam 33 will rise. In this case, the potential of the foundation beam 33 can be lowered by removing the low grounding object based on the contact position of the low grounding object.

After step S16, the processing unit 132 generates information that associates information indicating that current outflow due to interference of stray current has occurred, identification information of the steel foundation beam 33, and information indicating the measurement result of the ground potential. may be created, and the created stray current occurrence information may be output to the specifying unit 133 .
The identifying unit 133 acquires the current outflow occurrence information due to the interference of the stray current output by the processing unit 132, and the identification information of the steel foundation beam 33 included in the acquired current outflow occurrence information due to the interference of the stray current. Information associated with the information indicating the potential measurement result is acquired. Based on the obtained identification information of the steel foundation beam 33 and the information indicating the measurement result of the ground potential, the identifying unit 133 determines that the current outflow due to the interference of the stray current is detected from the ground potential measurement result. Derive the location where it occurred. The specifying unit 133 outputs to the display unit 150 information indicating the location where the current outflow due to the interference of the derived stray current has occurred.
When current outflow occurs due to interference of stray currents, corrosion is a problem because a large amount of current flows out from a portion with a high potential. In this case, the current can be lowered by inserting a resistor in the magnesium electrode circuit. If the potential does not decrease even if a resistance is inserted into the magnesium electrode circuit, the potential can be decreased by adding magnesium.

In the above-described embodiment, the case where the first insulating member 40 is included in the base structure 1 has been described, but the present invention is not limited to this example. For example, the first insulating member 40 may be removed from the base structure 1 .
In the above-described embodiment, the case where the outer peripheral surface of the pile 10 is coated with the pile insulating member 42 has been described, but the present invention is not limited to this example. For example, the outer peripheral surface of the pile 10 may not be coated with the pile insulating member 42 .
In the above-described embodiment, the case where the monitoring system 200 includes one monitoring device 100 has been described, but the present invention is not limited to this example. For example, monitoring system 200 may include multiple monitoring devices 100 .
In the above-described embodiment, the monitoring system 200 determines both the occurrence of current outflow due to interference of stray currents and the contact of a low-grounding object, but this example is limited. can't For example, the monitoring system 200 may determine that current outflow has occurred due to interference of stray currents, or that a low-grounding object has come into contact.
According to the monitoring system 200 according to the embodiment, the monitoring device 100 can determine that a current outflow has occurred due to interference of stray currents, which is a concern for corrosion protection of foundation beams made of system steel, and can detect the direction in which the stray currents have flowed. can be derived. Therefore, a resistor is inserted in the circuit of the magnesium electrode to lower the current. If the potential does not drop to the design value only with resistance, countermeasures such as adding magnesium can be taken.
In addition, the monitoring device 100 can determine contact with a low-contact object, which is a concern for corrosion prevention of foundation beams made of system steel, and can derive the contact position of the low-contact object. Therefore, it is possible to take countermeasures such as removing the low-grounding object based on the position where the low-contacting object comes into contact.
In the above-described embodiment, the monitoring system 200 monitors the ground potential of the foundation beam 33 and the anti-corrosion current generated by the anode, and based on the results of the monitoring link, the presence or absence of contact with other metals and the interference of stray currents. Although the case of detecting the presence or absence of current outflow due to is described, the present invention is not limited to this example. For example, the monitoring system 200 may monitor the ground potential of the foundation beam 33, and based on the results of the monitor link, may detect the presence or absence of contact with other metals and the presence or absence of current outflow due to interference of stray currents. The anti-corrosion current generated by the anode may be monitored, and based on the monitor link results, the presence or absence of contact with other metals and the presence or absence of current outflow due to interference of stray current may be detected.
Although the embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments are included in the scope and gist of the invention, as well as the invention described in the claims and the scope of equivalents thereof.

Note that the monitoring device 100 described above may be realized by a computer. In that case, a program for realizing the function of each functional block is recorded in a computer-readable recording medium. The program recorded on this recording medium may be loaded into the computer system and executed by the CPU. The "computer system" here includes hardware such as an OS (Operating System) and peripheral devices.
A "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, and a CD-ROM. A "computer-readable recording medium" includes a storage device such as a hard disk built in a computer system.

Furthermore, the "computer-readable recording medium" may include those that dynamically retain the program for a short period of time. For a short period of time, a program is dynamically stored in a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line.
In addition, the "computer-readable recording medium" may also include a medium that retains the program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client. Further, the program may be for realizing part of the functions described above. Moreover, the above program may be one capable of realizing the functions described above in combination with a program already recorded in a computer system. Moreover, the program may be implemented using a programmable logic device. A programmable logic device is, for example, an FPGA (Field Programmable Gate Array).

Note that the monitoring device 100 described above has a computer therein. Each process of the monitoring apparatus 100 described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by reading and executing this program by a computer.
Here, the computer-readable recording medium refers to magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like. Alternatively, the computer program may be distributed to a computer via a communication line, and the computer receiving the distribution may execute the program.
Further, the program may be for realizing part of the functions described above.
Furthermore, it may be a so-called difference file (difference program) that can realize the above-described functions in combination with a program already recorded in the computer system.

1 Foundation structure 10 Pile 11 Pile reinforcing bar 20 Floor slab 21 Slab reinforcing bar 30 Foundation part 31 Pile head joint part 32 Support part 33, 33ab-11 to 33ab-mn, 33bd-11 to 33bd-mn, 33dc-11 to 33dc-mn , 33ca-11 to 33ca-mn foundation beam 40 first insulating member 43 second insulating member 50 network 51a-11 to 51a-mn current supply unit 52 sacrificial anode 60a-11 to 60a-mn potential measuring device 70a-11 to 70a -mn current measuring device 71a-11 to 71a-mn reference electrode 72a-11 to 72a-mn coupon 100 monitoring device 110 communication unit 120 storage unit 130 information processing unit 140 operation unit 150 display unit

Claims (10)

A concrete pile embedded in the soil and having a plurality of pile reinforcing bars inside, and a concrete floor slab placed on the surface of the soil and having a plurality of slab reinforcing bars inside. , a steel foundation that connects the pile and the floor slab and is at least partially embedded in the soil, the foundation being a steel pile connected to the upper end of the pile The foundation of a foundation structure comprising a head joint, a steel strut extending upwardly from the pile head joint, and a steel foundation beam extending horizontally from the strut and supporting the floor slab. a current supply unit for supplying an anti-corrosion current to the
a reception unit that receives information indicating the ground potential of the foundation portion of the foundation structure;
Based on the information indicating the ground potential received by the reception unit, it is determined whether or not a low-grounding object is in contact with the foundation, and current outflow due to interference of stray current occurs in the steel foundation. a processing unit that performs either or both of determining whether the Using an anode buried in the soil as the current supply unit,
The reception unit receives information indicating an anticorrosion current generated by the anode,
Based on the information indicating the anticorrosion current received by the receiving unit, the processing unit determines whether or not a low-grounding object is in contact with the base, and determines whether current outflow occurs due to interference of stray current. 2. The monitoring system of claim 1, wherein the monitoring system performs either or both of: The reception unit receives information indicating the ground potential of the foundation of each of the plurality of foundation structures,
The monitoring system includes:
Based on information indicating the ground potential of each of the foundations of the plurality of foundation structures received by the reception unit, derivation of a position where a low-grounding object is in contact with the foundation, and interference of stray currents 3. The monitoring system according to claim 1 or claim 2, comprising an identification unit that performs either or both of deriving the location where the current drain is occurring. Based on the plane defined by the information indicating the ground potential of at least three locations, the identifying portion derives a position where the low-grounding object is in contact with the base portion, and current outflow occurs due to interference of stray current. 4. A monitoring system according to claim 3, which performs either or both of: derivation of the position of the moving object. The reception unit receives information indicating an anti-corrosion current generated by each of the plurality of anodes when each of the plurality of current supply units supplies a current to the base portion of each of the plurality of foundation structures,
Based on the information indicating the anti-corrosion current generated by each of the plurality of anodes received by the reception unit, derivation of the position where the low grounding object is in contact with the base portion and current outflow due to interference of stray current. 2. The monitoring system of claim 1, comprising an identification unit that performs one or both of derivation of position occurring. A concrete pile embedded in the soil and having a plurality of pile reinforcing bars inside, and a concrete floor slab placed on the surface of the soil and having a plurality of slab reinforcing bars inside. , a steel foundation that connects the pile and the floor slab and is at least partially embedded in the soil, the foundation being a steel pile connected to the upper end of the pile The foundation of a foundation structure comprising a head joint, a steel strut extending upwardly from the pile head joint, and a steel foundation beam extending horizontally from the strut and supporting the floor slab. supplying current to the section;
receiving information indicative of the ground potential of the base portion of the substructure;
Based on the information indicating the ground potential received in the receiving step, it is determined whether or not a low-grounding object is in contact with the base portion, and whether current outflow due to interference of stray current is occurring. and a monitoring method performed by a monitoring system comprising: In the receiving step, receiving information indicating the ground potential of the foundation of each of the plurality of foundation structures;
The monitoring method includes
Based on the information indicating the ground potential of each of the foundations of the plurality of foundations received in the receiving step, derivation of a position where a low-grounding object is in contact with the foundations, and interference of stray currents 7. A monitoring method according to claim 6, comprising the identifying steps of: deriving the location where the current drain is occurring, and/or deriving the location. A potential measuring device for measuring the ground potential is installed on each of the floor slabs of the plurality of foundation structures,
In the identifying step, one or both of derivation of the position of the floor slab where the low-grounding object is in contact with the base portion and derivation of the position of the floor slab where current outflow occurs due to interference of stray currents. 8. The monitoring method according to claim 7, wherein: The step of supplying current to the foundation uses a plurality of anodes embedded in the soil as a source of anticorrosive current,
In the receiving step, receiving information indicating an anticorrosion current generated by each of the plurality of anodes,
The monitoring method includes:
Based on the information indicating the anti-corrosion current generated by each of the plurality of anodes received in the receiving step, derivation of the position where the low grounding object is in contact with the base portion and current outflow due to interference of stray current. 7. The method of monitoring according to claim 6, comprising the identifying step of: deriving the position occurring and/or deriving the location. A current measuring device for measuring the anticorrosion current is installed on the floor slab of each of the plurality of foundation structures,
In the identifying step, one or both of derivation of the position of the floor slab where the low-grounding object is in contact with the base portion and derivation of the position of the floor slab where current outflow occurs due to interference of stray currents. 10. The monitoring method according to claim 9, wherein:

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