Electrical connection methods in cathodic protection

Abstract

To provide an electrical connection method that allows for easy construction of a structure that can appropriately form and maintain a reliable electrical conductivity between the conductive wire and the reinforcing steel in cathodic protection, which involves supplying current to reinforcing steel within concrete using a conductive wire. [Solution] The electrical connection method for cathodic protection according to the present invention is an electrical connection method for a target reinforcing bar in cathodic protection of a concrete structure, wherein a current-carrying hole is formed that extends from the concrete surface to the reinforcing bar, a current-carrying wire and a contact pressure-applying member that ensures electrical connection of the tip of the current-carrying wire to the reinforcing bar are inserted into the current-carrying hole, and the contact pressure-applying member is plastically deformed by a driving jig to press the tip of the current-carrying wire toward the reinforcing bar and prevent the tip of the current-carrying wire from coming loose, thereby constructing a structure that can easily form and maintain a reliable electrical connection between the current-carrying wire and the reinforcing bar.

Description

Technical Field

[0001] The present invention relates to a method for electrically connecting a target reinforcing bar in the cathodic protection of a reinforced concrete structure. Background Art

[0002] Conventionally, in concrete structures (reinforced concrete structures and prestressed concrete structures), cathodic protection has been performed in which corrosion of the reinforcing bars in concrete can be prevented by supplying current to the reinforcing bars. In this specification, reinforcing steel bars embedded in reinforced concrete and PC steel materials embedded in prestressed concrete are collectively referred to as "reinforcing bars".

[0003] In this type of cathodic protection, there are mainly two methods: a galvanic anode method, in which a metal having a higher ionization tendency than iron constituting the reinforcing bar is provided as a galvanic anode (sacrificial anode), and the galvanic anode and the reinforcing bar are electrically connected to generate a protective current; and an external power supply method, in which a protective current is supplied to the reinforcing bar from an external power supply. In either method, it is important to ensure electrical conduction to the reinforcing bars in the concrete.

[0004] Therefore, as shown in Patent Documents 1 and 2 below, a technique has been disclosed in which an anchor hole leading to a reinforcing bar in concrete is formed, an anchor made of a metal rod such as a bolt shaft is inserted into the anchor hole, and the reinforcing bar is electrically connected via the anchor.

[0005] However, as in Patent Documents 1 and 2 below, in the configuration of electrically connecting to the reinforcing bar via a metal rod-shaped body, since the metal rod-shaped body does not easily deform, it is necessary to strictly adjust the direction and position of the anchor hole, and there is a possibility that it cannot cope with micro-deformation of the structure due to temperature expansion and contraction or the like. Prior Art Documents Patent Documents

[0006] Patent Document 1 Patent No. 6875467 [Patent Document 2] Patent No. 6875468 [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, the above problems can be easily solved by making electrical connections to the reinforcing bars in concrete via metal wires (electrical wires) instead of metal rods. However, this then presents the problem of requiring meticulous and skilled work to ensure a secure connection to the reinforcing bars. [Means for solving the problem]

[0008] The present invention provides a method for easily constructing a structure that can reliably form and maintain a stable electrical connection between a metal wire, i.e., a conductive wire, and reinforcing steel in concrete, in an electrochemical corrosion prevention method that uses a conductive wire to conduct electricity.

[0009] In summary, the electrical connection method for cathodic protection according to the present invention is an electrical connection method for a target reinforcing bar in cathodic protection of a concrete structure, wherein an electrical conduction hole is formed that extends from the concrete surface to the reinforcing bar, and the electrical conduction hole It consists of exposed metal wires with the tip shaped into a spiral. Power lines and 、 The powered wire spiral tip Place it behind Insert the contact pressure applying member, The contact pressure applying member is pressed with the driving jig. the above spiral The tip is attached to the above reinforcing bar. By pressing, the above spiral shape tip It undergoes elastic deformation, and its restoring force The above reinforcing bars to be forced Along with, The above contact pressure applying member is plastically deformed and enlarged in diameter by the above driving jig, thereby forming the helical shape By preventing the tip from coming loose, a structure can be constructed that easily establishes and maintains a reliable electrical connection between the powered wire and the reinforcing bar. Furthermore, by shaping the tip of the conductive wire into a spiral, the contact area with the reinforcing bar is increased, and it becomes easier to press it towards the reinforcing bar, thereby ensuring more reliable electrical conductivity.

[0010] Preferably, the contact pressure applying member is made of a conductive metal ellipsoid, so that its conductivity complements the electrical connection (conductivity) between the current wire and the reinforcing bar, its shape facilitates insertion into the current-carrying hole, and it can secure a volume that reliably expands in diameter during plastic deformation.

[0011] More preferably, the contact pressure applying member has an insertion hole through which the energizing wire is inserted, making it easier to insert the energizing wire together with the energizing wire into the energizing hole, and also making it easier to press the tip of the energizing wire toward the reinforcing bar.

[0012] Furthermore, by making the contact pressure applying member out of lead, plastic deformation within the current-carrying hole is facilitated, and the conductivity of lead can complement the electrical connection between the current-carrying wire and the reinforcing bar.

[0014] Preferably, by using an iron wire for the current-carrying wire, the current-carrying wire is made of the same metal as the reinforcing steel, thereby preventing instability in the electrical connection due to the potential difference between different metals.

[0015] Furthermore, since the above-mentioned driving jig is made of a metal rod-shaped body, it can be inserted into the current-carrying hole and deform the contact pressure-applying member with its tip.

[0016] Preferably, the above-mentioned driving jig During the operation using the said driving jig A receiving groove is provided to receive the above-mentioned power supply wires. The receiving groove opens at the tip and side of the driving jig and extends toward the rear end, and is configured to gradually become shallower from the tip to the rear end of the driving jig. As a result, the power supply wire does not get in the way when working to deform the contact pressure applying member. Furthermore, the receiving groove is made to the minimum necessary size while allowing the tip of the driving jig to move freely within the energizing hole.

[0017] More preferably, the receiving groove of the driving jig is configured to gradually become shallower from the front end to the rear end of the driving jig, thereby allowing the front end of the driving jig to move freely within the energizing hole while keeping the receiving groove to the minimum necessary size. [Effects of the Invention]

[0018] According to the electrical connection method for cathodic protection of the present invention, the reinforcing steel in concrete and the current-carrying wire can be properly electrically connected, and a stable conductive state can be easily constructed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [Figure 1] It is an explanatory diagram showing the outline of cathodic protection for a concrete structure using the electrical connection method according to the present invention. [Figure 2] It is a cross-sectional view showing a state where a hole for current supply is formed by performing drilling treatment on concrete. [Figure 3] It is a cross-sectional view showing a state where a current-carrying wire and a contact pressure applying member are inserted into the current supply hole. [Figure 4] It is a cross-sectional view showing a state where the contact pressure applying member is deformed by a driving jig. [Figure 5] It is a cross-sectional view showing a state where the plastically deformed contact pressure applying member presses the tip end of the current-carrying wire toward the reinforcing steel. [Figure 6] It is a perspective view showing another example of the driving jig. [Figure 7] It is a cross-sectional view showing a state where the contact pressure applying member is deformed by the driving jig shown in Fig. 6. MODE FOR CARRYING OUT THE INVENTION

[0020] Hereinafter, an optimal embodiment of the electrical connection method for cathodic protection according to the present invention (hereinafter simply referred to as "electrical connection method") will be described based on Figs. 1 to 7.

[0021] <Basic Configuration of Electrical Connection Method> As shown in Fig. 1, the electrical connection method according to the present invention is an electrical connection method performed on the reinforcing steel F embedded in concrete C of a concrete structure when performing cathodic protection on the reinforcing steel F, and is performed via a current supply hole H reaching from the surface Ca of the concrete C to the reinforcing steel F and a current-carrying wire 1 (1A) inserted into the current supply hole H.

[0022] In Figure 1, 10 is the sacrificial anode, 11 (11A and 11B) are cover members for protecting the sacrificial anode 10, and 12 are fixing means such as bolts for fixing the cover members 11 (11A and 11B) to the concrete surface Ca. The sacrificial anode 10 is made of a metal with a higher ionization tendency (lower potential) than the iron that makes up the reinforcing steel F, such as zinc, aluminum, zinc alloy, aluminum alloy, or aluminum-magnesium alloy. Although Figure 1 is drawn based on the sacrificial anode method, the present invention can also accommodate an external power supply method as long as cathodic protection is performed using the current-carrying wire 1 and current-carrying holes H.

[0023] <Drilling process> This process, as shown in Figure 2, involves drilling a conductive hole H that extends from the surface Ca of the concrete C to the reinforcing bar F, using a known drilling method such as a drill. The diameter of the conductive hole H can be adjusted as appropriate based on the diameter of the reinforcing bar F and the size of the driving jig 4, which will be described later.

[0024] <Power wire insertion process> Following the drilling process described above, in this process, as shown in Figure 3, a current-carrying wire 1 (1A) and a contact pressure-applying member 3 are inserted into the current-carrying hole H, and the tip 1a of the current-carrying wire 1 is brought into contact with the reinforcing bar F to ensure electrical conductivity.

[0025] Here, we will describe the energizing wire 1 and the contact pressure applying member 3.

[0026] Regarding powered wire 1: In this invention, the current-carrying wire 1(1A) can be a lead wire covered with a known insulating material, or an uncovered, bare metal wire. The metal wire is not particularly limited as long as it is made of a metal with appropriate conductivity, but preferably, a wire made of iron (iron wire) is used. This is because the current-carrying wire 1(1A) can be made of the same metal as the reinforcing bar F to be protected from corrosion, thereby preventing instability in the electrical connection due to the potential difference between different metals. The diameter of the current-carrying wire 1 can be adjusted as appropriate.

[0027] The current-carrying wire 1 may connect the galvanic anode 10 and an external power source (not shown) to the reinforcing bar F in a single wire, but preferably, as shown in Figure 1, the current-carrying wire 1(1A) that connects to the reinforcing bar F and the current-carrying wire 1(1B) that connects to the galvanic anode 10 and the external power source are connected by a connector 2. With this configuration, for example, if the current-carrying wire 1A is made of iron and the current-carrying wire 1B is made of copper, current can be carried through the current-carrying wire 1A while preventing instability in the electrical connection due to the potential difference between the metals, and current can be carried through the current-carrying wire 1B with high efficiency. In addition, it is possible to flexibly accommodate the positional relationship between the reinforcing bar F and the current-carrying holes H and the galvanic anode 10 and the external power source.

[0028] Furthermore, the tip portion 1a of the conductive wire 1 is preferably formed into a spiral shape, as shown in Figure 3. This increases the contact area with the reinforcing bar F and makes it easier to press towards the reinforcing bar F, thereby ensuring a reliable electrical connection. More preferably, the tip portion 1a is formed into a truncated conical spiral or a conical spiral. That is, as shown in Figure 3, if the conductive wire 1 is formed into a tapered truncated conical spiral or a conical spiral with a decreasing radius towards the tip, or into a tapered truncated conical spiral or a conical spiral with a increasing radius towards the tip, the tip portion 1a will elastically deform under pressure from the contact pressure applying member 3, and the restoring force (elastic rebound force) will press the tip portion 1a against the reinforcing bar F. This ensures stable contact pressure with respect to the reinforcing bar F, making it easier to maintain conductivity even with vibrations or changes over time.

[0029] Regarding the contact pressure applying member 3: As will be described later, the contact pressure applying member 3 is a member that plastically deforms within the energizing hole H to press the tip 1a of the energizing wire 1 toward the reinforcing bar F and to prevent the tip 1a of the energizing wire 1 from coming loose.

[0030] The contact pressure applying member 3 is not particularly limited in shape, but preferably it is an ellipsoidal sphere like a rugby ball, as shown in Figure 3. By aligning the long axis of the contact pressure applying member 3 with the axis of the current-carrying hole H, it can be easily inserted into the current-carrying hole H. Furthermore, while facilitating insertion into the current-carrying hole H in this way, it is possible to ensure sufficient volume to reliably expand in diameter during plastic deformation to prevent it from coming loose. The size (volume) of the contact pressure applying member 3 can be adjusted as appropriate.

[0031] Furthermore, the contact pressure applying member 3 can be made of any material that can be easily plastically deformed, but it is preferably made of a conductive metal. This is to complement the electrical connection (conductivity) between the current-carrying wire 1 and the reinforcing bar F. More preferably, it is made of lead. This is because it is a material that combines conductivity with ease of plastic deformation.

[0032] Furthermore, as shown in Figure 3, the contact pressure applying member 3 has an insertion hole 3a through which the energizing wire 1 is inserted, making it easier to insert the energizing wire 1 together with the energizing wire 1 into the energizing hole H, and also making it easier to press the tip 1a of the energizing wire 1 toward the reinforcing bar F.

[0033] <Contact pressure application member deformation process> Following the above-described process of inserting the energized wire, the process involves using a driving jig 4 to tap the contact pressure applying member 3, as shown in Figure 4, to plastically deform the contact pressure applying member 3, as shown in Figure 5, thereby pressing the tip 1a of the energized wire 1 toward the reinforcing bar F and preventing the tip 1a of the energized wire 1 from coming loose. In other words, it is a process of applying appropriate contact pressure to the tip 1a of the energized wire 1 and maintaining that contact pressure.

[0034] Now, let's explain the driving jig 4.

[0035] Regarding the driving jig 4: The driving jig 4 is preferably made of a metal rod and, as shown in Figure 4, is inserted into the current-carrying hole H and the contact pressure-applying member 3 is struck or pressed with its tip 4a to deform the contact pressure-applying member 3 so that it expands in diameter and becomes large enough to contact the inner circumferential surface Ha of the current-carrying hole H, as shown in Figure 5. The metal that makes up the driving jig 4 is not particularly limited as long as it can deform the contact pressure-applying member 3, but iron is preferably used. The length, thickness, and cross-sectional shape of the driving jig 4 can be appropriately adjusted according to the diameter of the current-carrying hole H and the diameter of the current-carrying wire 1.

[0036] At the same time, the contact pressure applying member 3 presses the tip 1a of the energizing wire 1 against the reinforcing bar F. Therefore, even if the tip 1a of the energizing wire 1 was not in contact with the reinforcing bar F during the energizing wire insertion process described above, the tip 1a is reliably pressed towards the reinforcing bar F during this process. Furthermore, as described above, since the tip 1a is shaped into a truncated conical spiral or a conical spiral, the tip 1a is pressed by the contact pressure applying member 3 and elastically deforms, and its restoring force (elastic rebound force) strongly presses it against the reinforcing bar F, ensuring a stable conductive state through reliable contact pressure.

[0037] Preferably, as shown in Figure 6, by providing a receiving groove 4b for receiving the energizing wire 1 in the driving jig 4, the energizing wire 1 will not get in the way during the work of deforming the contact pressure applying member 3, as shown in Figure 7.

[0038] More preferably, as shown in Figure 6, the receiving groove 4b is configured to gradually become shallower from the front end to the rear end of the driving jig 4, thereby allowing the front end 4a to move freely within the energizing hole H while keeping the receiving groove 4 to the minimum necessary size.

[0039] This process completes the electrical connection structure between the power supply wire 1 and the reinforcing bar F. The power supply hole H can be filled with mortar or the like as needed.

[0040] As described above, the electrical connection method for cathodic protection according to the present invention makes it possible to appropriately electrically connect the reinforcing bars F in the concrete C of a concrete structure to the energizing wire 1 and easily establish a stable conductive state.

[0041] In particular, the shape and material of the tip 1a of the conductive wire 1, as well as the plastic deformation of the contact pressure applying member 3, make it possible to construct a structure that applies and maintains appropriate contact pressure to the tip 1a of the conductive wire 1, thereby ensuring electrical conductivity. [Explanation of symbols]

[0042] 1...Electrified wire, 1a...Tip, 1A...First electrified wire, 1B...Second electrified wire, 2...Connector, 3...Contact pressure applying member, 3a...Insertion hole, 4...Driving jig, 4a...Tip, 4b...Receiving groove, 10...Sacrificial anode, 11...Cover member, 11A...First cover member, 11B...Second cover member, 12...Fixing means, H...Electrified hole, Ha...Inner circumferential surface, F...Reinforcement bar, C...Concrete, Ca...Surface.

Claims

1. A method for electrically connecting to a target reinforcing bar in cathodic protection of a concrete structure, characterized in that: a current-carrying hole is formed from the concrete surface to the reinforcing bar; a current-carrying wire made of exposed metal wire with a spirally shaped tip and a contact pressure-applying member positioned behind the spiral tip of the current-carrying wire are inserted into the current-carrying hole; the contact pressure-applying member is pressed with a driving jig to press the spiral tip against the reinforcing bar, causing the spiral tip to elastically deform and be pressed against the reinforcing bar by its restoring force; and the contact pressure-applying member is plastically deformed and expanded in diameter by the driving jig, thereby preventing the spiral tip from coming loose.

2. The electrical connection method in cathodic protection according to claim 1, characterized in that the contact pressure applying member is made of an ellipsoidal sphere of a conductive metal.

3. The electrical connection method in cathodic protection according to claim 2, characterized in that the contact pressure applying member has an insertion hole through which the current-carrying wire is inserted.

4. The electrical connection method in cathodic protection according to claim 1, characterized in that the contact pressure applying member is made of lead.

5. The electrical connection method in cathodic protection according to claim 1, characterized in that the above-mentioned current-carrying wire is an iron wire.

6. The method for electrical connection in cathodic protection according to claim 1, characterized in that the above-mentioned driving jig consists of a metal rod-shaped body.

7. The method for electrical connection in cathodic protection according to claim 6, characterized in that the above-mentioned driving jig has a receiving groove for receiving the above-mentioned power supply wire when working with the driving jig, and the receiving groove opens at the tip and side of the driving jig and extends toward the rear end, and gradually becomes shallower from the tip to the rear end of the driving jig.

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