JP5740851B2 - Steel sheet pile electrodeposition protection system - Google Patents

Description

The present invention relates to an electrodeposition anticorrosion apparatus for steel sheet piles.

  In general, some steel marine structures such as steel sheet piles provided on the quay for revetment, steel pipe piles provided on bridges and piers, etc., or steel caissons whose concrete structures are covered with steel members It is provided in a state where it is submerged in seawater, and is exposed to an environment where rust is likely to occur.

  Accordingly, in such marine steel structures, rust is generated due to long-term use and the thickness is reduced and the strength is reduced. Therefore, it is necessary to perform reinforcement work or replacement work. Since a great deal of cost is required for construction, it is attempted to extend the life of the marine steel structure by means of anticorrosion, anticorrosion, or a combination thereof.

FIG. 18 is a schematic view showing an example of the conventional electrodeposition coating formation on the marine steel structure 1, and the anode 3 is disposed at a predetermined interval with respect to the submerged portion 2 submerged in the seawater of the marine steel structure 1. By providing a DC power source 4 between the anode 3 and the marine steel structure 1 and energizing a DC current, calcium ions (Ca ²⁺ ), magnesium ions (Mg ²⁺ ) and the like dissolved in seawater The cations migrate in the seawater toward the marine steel structure 1 as a cathode, and electrons are obtained in the marine steel structure 1. CaCO ₃ and Mg are formed on the surface of the submerged portion 2 of the marine steel structure 1. An anticorrosion electrodeposition coating 5 (electrocoating layer) mainly composed of (OH) ₂ or the like is formed, and the submerged portion 2 of the marine steel structure 1 is anticorrosion by the anticorrosion electrodeposition coating 5. .

  In the conventional case, as the anode 3, an electrode having a very general shape such as a round bar or a plate is used, and the current situation is that electrodeposition is performed.

  For example, Patent Document 1 shows a general technical level of the anticorrosion method for marine steel structures as described above.

Japanese Patent No. 4146737

  However, as described above, when electrodeposition is performed by using an electrode having a very general shape such as a round bar or a plate as the anode 3, particularly when the marine steel structure 1 is a steel sheet pile, the steel sheet pile is used. Has a concavo-convex shape, the distance between the anode 3 and the anode 3 is non-uniform, resulting in a difference in the energization amount, and the thickness of the anticorrosion electrodeposition coating 5 formed on the surface of the steel sheet pile varies greatly. It has become a problem to occur.

In view of such circumstances, the present invention intends to provide a steel sheet pile electrodeposition anticorrosion apparatus capable of forming an anticorrosion electrodeposition film having a uniform thickness on the surface of the steel sheet pile.

In the present invention , an anode is provided at a required interval with respect to a submerged portion of the steel sheet pile connected and arranged so that the uneven portion is formed, and a direct current power source is provided between the anode and the steel sheet pile. In the electrodeposition anticorrosion device for steel sheet piles, which forms an anticorrosion electrodeposition coating on the surface of the submerged portion of the steel sheet pile by passing a direct current,
An anode having at least three front and both side surfaces facing the concave inner surface of the steel sheet pile,
When the pitch in the width direction of the recesses and projections of the steel sheet piles to be connected is P [cm] and the depth between the recesses and projections is D [cm], the front and both sides of the anode The distance c [cm] between the electrode and the inner surface of the concave portion of the steel sheet pile
1 ≦ c ≦ 0.05 × (P + 2D)
And projecting amounts s [cm] of both side surfaces of the anode from the concave portion for allowing an electric current to flow through the convex surface of the steel sheet pile.
0.75 × D ≦ s ≦ 1.25 × D
And a holding means for holding the,
The holding means includes an installation bar provided so as to project from the quay side to the sea, a fixing bar suspended from the installation bar and attached with an anode, and attached to a lower end of the fixing bar and sinking to the seabed A plurality of anodes are combined into a set with a holding bar and a fixing bar for the holding means, and the anodes are installed at a time for a plurality of recesses. The present invention relates to a steel sheet pile electrodeposition anticorrosion device.

  According to the above means, the following operation can be obtained.

  An anode having at least three front and opposite sides facing the inner surface of the concave portion of the steel sheet pile is used, the pitch in the width direction of the concave and convex portions of the steel sheet pile to be connected is P [cm], and the concave portion and When the depth between the convex portions is D [cm], the distance c [cm] between the three surfaces of the front surface and both side surfaces of the anode and the inner surface of the concave portion of the steel sheet pile is 1 ≦ c ≦ 0.05 × ( P + 2D), and the overhang amount s [cm] of both side surfaces of the anode from the concave portion for flowing current to the convex surface of the steel sheet pile is maintained at 0.75 × D ≦ s ≦ 1.25 × D. In this state, when an electric current is passed between the anode and the steel sheet pile, unlike the conventional method of performing electrodeposition using an electrode having a general shape such as a round bar or a plate as the anode, the steel sheet pile is used. Even if it has a concave-convex shape, it is difficult to make a difference in the amount of electricity applied to the surface of the steel sheet pile. It is avoided that the thickness of the formed anticorrosion electrodeposition film greatly varies.

According to the electrodeposition anticorrosion device for steel sheet piles of the present invention, it is possible to form an anticorrosion electrodeposition coating having a uniform thickness on the surface of the steel sheet pile , and furthermore, it is possible to perform the electrodeposition anticorrosion device very efficiently. An excellent effect can be achieved.

It is a general | schematic structure top view which shows the Example of this invention. It is a flowchart which shows the analysis process in the analysis software used for verification of the Example of this invention. (A) is a plan view showing an example in which an anode having a rectangular cross section is arranged in a concave portion of a steel sheet pile in a Z-type connection model in which steel sheet piles called Z-shapes are connected and arranged according to JIS standards. It is a diagram which shows the relationship between the distance between poles and the maximum / minimum value of current density in a shape connection model. (A) is a plan view showing an example in which an anode having a rectangular cross-section is arranged so as to partially protrude in a concave portion of a steel sheet pile in a Z-shaped connection model in which steel sheet piles called Z-shape are connected and arranged according to JIS standards; (B) is a diagram showing the relationship between the overhang amount of the anode and the maximum and minimum values of current density in the Z-shaped connection model. (A) is a plan view showing an example in which a trapezoidal cross-sectional anode is disposed in a concave portion of a steel sheet pile in a U-shaped connection model in which steel sheet piles referred to as U shapes in JIS standards are connected and arranged; It is a diagram which shows the relationship between the distance between poles and the maximum / minimum value of current density in a shape connection model. (A) is a plan view showing an example in which an anode having a trapezoidal cross section is arranged so as to partially protrude from a concave portion of a steel sheet pile in a U-shaped connection model in which steel sheet piles called U-shapes are connected and arranged according to JIS standards; (B) is a diagram showing the relationship between the protruding amount of the anode and the maximum and minimum values of current density in the U-shaped connection model. A plan view showing an example in which an anode having a rectangular cross section is arranged in a concave portion of a steel sheet pile in order to create a Z-linked model 1/2 scale steel sheet pile and verify it by a real test and a 1/2 scale simulation. It is. It is a plot figure which shows the relationship between the distance between electrodes in the 1/2 scale Z-shaped connection model shown in FIG. 7, and the variation in overvoltage distribution. In order to create a 1/2 scale steel sheet pile of the Z-shaped connection model, and to verify by actual test and 1/2 scale simulation, a part of the anode with a rectangular cross section is projected in the recess of the steel sheet pile FIG. FIG. 10 is a diagram showing the relationship between the amount of overhang of the anode and the variation in overvoltage distribution in the 1/2 scale Z-shaped connection model shown in FIG. 9. In the Example of this invention, it is a general | schematic structure top view which shows the state which the mutually adjacent anodes contacted. It is a figure which shows the cross-sectional shape of the anode in the Example of this invention, Comprising: (a) The figure which shows a trapezoid and a solid anode, (b) is a figure which shows a trapezoid and a hollow anode, (c) is a mesh The figure which shows the anode of a structure, (d) is a figure which shows the U-shaped anode which removed the trapezoid-shaped bottom surface. It is a figure which shows the surface which opposes the steel sheet pile of the anode in the Example of this invention, Comprising: (a) is a figure which shows a mesh-shaped anode, (b) is a figure which shows a perforated anode. It is the schematic which shows the holding means in the Example of this invention, Comprising: (a) is a front view, (b) is a side view. It is a side view which shows an example of the procedure which installs the anode by the holding means in the Example of this invention. It is a side view which shows the other example of the procedure which installs the anode by the holding means in the Example of this invention. It is a top view which shows the example which put together the several anode in the Example of this invention into one set with the bar for installation of a holding means, and the bar for fixing. It is the schematic which shows an example of the electrodeposition film formation to the conventional marine steel structure.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of the present invention, in which the steel submerged portion 2 submerged in seawater of a steel sheet pile 1Y as a marine steel structure 1 connected and arranged so as to form the concave portion 1Ya and the convex portion 1Yb. Using the anode 3 having at least three front surfaces 3a and both side surfaces 3b facing each other so as to follow the inner surface of the concave portion 1Ya of the sheet pile 1Y, the pitch in the width direction of the concave portion 1Ya and the convex portion 1Yb of the steel sheet pile 1Y to be connected is P And the depth between the concave portion 1Ya and the convex portion 1Yb is D [cm], the distance c between the three surfaces of the front surface 3a and both side surfaces 3b of the anode 3 and the inner surface of the concave portion 1Ya of the steel sheet pile 1Y [Cm] is maintained at 1 ≦ c ≦ 0.05 × (P + 2D), and the protruding amount s [of both side surfaces 3b of the anode 3 from the concave portion 1Ya for flowing current to the surface of the convex portion 1Yb of the steel sheet pile 1Y. cm] is 0.75 × D ≦ s ≦ 1.25 × D or more In the holding state, in which so as to energize the DC power supply 4 (see FIG. 18) between the anode 3 and the steel sheet pile 1Y.

Here, in order to confirm the effectiveness of the present embodiment by simulation, the present inventors etc. are commercially available analysis software “film thickness guider ver. 4.4”.
(Uemura Industrial Co., Ltd .; http://www.uyemura.co.jp/uyemura/epps/index.htm)
Was used for verification. The analysis software “film thickness guide” requires two programs: a pre-post processor that creates an analysis model and visualizes the analysis results, and an analysis solver that performs the analysis. As a processor "Femap ver. 9.2 / Japanese version" (UGS Corp.)
The software used to create a finite element analysis model that runs on Windows and to post-process (visualize) the analysis results was used.

  As shown in the flowchart of FIG. 2, the analysis process by the “film thickness guide” that is the analysis software includes, as input data, the electrical conductivity of seawater, the analysis region, the energization period, the total current value, the cathode polarization, the anodic polarization, The material properties of the coating and analysis setting parameters are input to the pre-post processor, and a model of the steel sheet pile 1Y is created by the pre-post processor, the model is converted into data and input to the analysis solver, current density distribution analysis is performed, The data file obtained by the analysis solver is input again to the pre-post processor and the analysis result is displayed, and various examinations regarding the current density distribution can be performed from the displayed analysis result.

The specific numerical value of the input data is
Electrical conductivity of seawater: 4.7882 [S / m]
Analysis area: 40 x 20 x 1 [m] (width x depth x water depth) seawater area Energization period: 864000 [s] (= 10 days)
Total current value: set so that the maximum value of current density in steel sheet pile 1Y is 4.0 [A / m ² ] Electrochemical equivalent of film: 2.5 × 10 ⁻⁷ [kg / C]
Coating density: 1200 [kg / m ³ ]
It was.

Incidentally, the cathode polarization and the anode polarization are relational expressions of overvoltage-current density in the steel sheet pile 1Y and the anode 3 as cathodes, and determine the electrochemical characteristics of each electrode. The overvoltage refers to a potential that deviates from the resting potential, indicating how much lower the cathodic polarization overvoltage is than the resting potential, and how much higher the anodic polarization overvoltage is than the resting potential. This polarization data varies depending on the environment such as water quality / tidal current and material characteristics of each pole.In this verification, cathode polarization was collected using SS400 steel specimens in the actual environment, and anodic polarization was measured in an indoor aquarium experiment. What was measured using a 1 [cm ² ] zinc plate was used. Although it is irrelevant to the result of this analysis, it is necessary to input data on the physical properties of the deposited film. Therefore, assuming that the film is Mg (OH) ₂ , its electrochemical equivalent (deposited on the cathode) Amount) and density were set.

Moreover, the analysis setting parameter used as the input data is a text command for the pre-post processor (Femap),
1. Control data integer type
CNTI, dimension, number of Gauss points, number of convergence iterations, solution, analysis content, nonlinear judgment value, CG method judgment value, in-core, restart designation, nodal movement designation
CNTI, 4, 2, 50, 4, 2, 3, 12, 1, 0, 0
2. Control data real type
CNTR, depth, total current, nonlinear relaxation coefficient, film thickness calculation relaxation coefficient
CNTR, 1.0, (total current value), 0.99, 0.0
3. Step data
STEP, serial number, elapsed time, number of time divisions, total current, potential, output control, second potential setting, third potential setting, restart data file output
STEP, 1, 864000, 1, 0, 0, 0, 0, 0, 0
I entered it in the form of The reason why 0 is input to the total current in the step data is to use the data input in the control data real number type as it is. Further, the second potential setting and the third potential setting in the step data are not used in this case, so 0 is input.

  First, in order to simplify the analysis, as shown in FIG. 3A, the steel sheet pile 1Y, which is referred to as Z-shape in the JIS standard, is connected so that the concave portion 1Ya and the convex portion 1Yb are formed. An arranged Z-shaped connection model is created, and the pitch in the width direction of the concave portion 1Ya and the convex portion 1Yb of the steel sheet pile 1Y in the Z-shaped connection model is P = 40 [cm], and the depth is D = 34 [cm]. In order to install the steel sheet pile 1Y with a concavo-convex shape at right angles on the end face regarded as a quay in the analysis area of 40 × 20 × 1 [m], When the anode 3 having a rectangular cross section is arranged in the five concave portions 1Ya in the central portion in the width direction of the electrode, and the inter-electrode distance c is changed under six conditions of 2, 3, 5, 7, 10, 15 [cm] , The maximum current density of the three recesses 1 Ya (the portion surrounded by the phantom line in FIG. 3A) An evaluation of the uniformity of the current by looking at the small value and distribution was performed.

When the inter-electrode distance c is 2, 3, 5 [cm], the maximum value of the current density at the steel sheet pile 1Y is about 4.0 [A / m ² ] as shown in FIG. If the current applied to one anode 3 is 5.6 to 5.8 [A], the current density of the recess 1Ya (back surface and both side surfaces) of the steel sheet pile 1Y in the evaluation range is approximately 3.0 to 4.0 [A / m ² ]. However, when the inter-electrode distance c is 7 [cm] or more, the anode 3 has a maximum current density of about 4.0 [A / m ² ] in the steel sheet pile 1Y. Even if the current to be energized per wire is set to 5.0 to 5.6 [A], the current does not distribute in the back corner of the recess 1Ya of the steel sheet pile 1Y, and the minimum value of the current density gradually decreases. Is getting bigger. As this factor, it is considered that there is a geometric relationship with the steel sheet pile 1Y surface of the anode 3 and an opposing area. That is, when the inter-electrode distance c is increased, the distance between the back corner of the recess 1Ya of the steel sheet pile 1Y and the anode 3 is increased, and the area of the anode 3 facing the recess 1Ya of the steel sheet pile 1Y is small. Since the current density is increased and the current is concentrated in a portion where the distance from the anode 3 is short, it becomes difficult for the current to flow in the back corner portion, so that the variation in the current density in the concave portion 1Ya of the steel sheet pile 1Y has increased. Conceivable. The voltage applied to the anode 3 is 1 to 20 [V].

  Subsequently, as shown in FIG. 4 (a), the concave and convex portions 1Ya and 1Yb of the steel sheet pile 1Y in the Z-shaped connection model have a pitch in the width direction of P = 40 [cm] and a depth of D = 34 [cm]. In order to install the steel sheet pile 1Y having a right shape on the end face regarded as a quay in the analysis area of 40 × 20 × 1 [m], and to consider the superposition of currents by the anodes 3, the width of the steel sheet pile 1Y A model in which the anode 3 having a rectangular cross section is arranged so as to partially protrude in the five concave portions 1Ya in the center in the direction is created, and the distance c between the electrodes is 5 [cm] based on the analysis result (see FIG. 3). When the protruding amount s of the anode 3 is changed under eight conditions of 0, 10, 20, 30, 40, 50, 70, and 100 [cm] in a fixed state, the three recesses 1Ya and the two protrusions 1Yb By checking the maximum and minimum values and distribution of the current density (the part surrounded by the phantom line in FIG. 4A), Evaluation on uniformity was performed.

When the overhang s is 0, 10, 20 [cm], the maximum value of the current density in the steel sheet pile 1Y is about 4.0 [A / m ² ] as shown in FIG. Even if the current applied to each anode 3 is 6.0 [A], the variation in the current density distribution of the concave portion 1Ya (back surface and both side surfaces) and the convex portion 1Yb of the steel sheet pile 1Y in the evaluation range is large. When the protruding amount s of the anode 3 is set to 30 [cm] or more, the maximum value of the current density in the steel sheet pile 1Y is about 4.0 [A / m ² ] per one anode 3 Assuming that the current to be applied is 6.0 to 6.4 [A], the result shows that the range of the fluctuation range of the maximum and minimum values of the current density does not change much. Therefore, in view of the quantity surface, it is considered optimal to set the protruding amount s of the anode 3 to 30 [cm] from the convex portion 1Yb of the steel sheet pile 1Y.

  Next, as shown in FIG. 5 (a), a U-shaped connection model is created in which steel sheet piles 1Y, which are referred to as U shapes in the JIS standard, are connected and arranged so that the concave portions 1Ya and the convex portions 1Yb are formed. The pitch in the width direction of the concave portion 1Ya and the convex portion 1Yb of the steel sheet pile 1Y in the U-shaped connection model is P = 40 [cm] (the innermost width of the concave portion 1Ya and the width of the tip portion of the convex portion 1Yb are both 30.6 [cm]. The depth of the inclined portion in the depth direction is 9.4 [cm]), the depth is D = 30 [cm], and the concave and convex trapezoidal steel sheet pile 1Y has an analysis area of 40 × 20 × 1 [m]. A model in which the trapezoidal shaped anodes 3 are arranged in the five recesses 1Ya in the central portion in the width direction of the steel sheet pile 1Y in order to be installed on the end face regarded as a quay and to consider the superposition of currents by the respective anodes 3 Created and changed the distance c between the six conditions of 2, 3, 5, 7, 10, 15 [cm] When is a recess 1Ya three locations were evaluated regarding the uniformity of current by looking at the maximum and minimum values and the distribution of the current density (in FIG. 5 (a), the enclosed portion in phantom).

In this U-shaped connection model, when the inter-electrode distance c is 2, 3, 5, 7 [cm], the maximum value of the current density in the steel sheet pile 1Y is 4.0 [as shown in FIG. Assuming that the current applied to each anode 3 is 5.0 [A] so as to be about A / m ² ], the current density of the concave portion 1Ya (back surface and both side surfaces) of the steel sheet pile 1Y in the evaluation range is approximately 3.0 to Although it was within the range of 4.0 [A / m ² ], when the inter-electrode distance c is 10 [cm] or more, the maximum value of the current density in the steel sheet pile 1Y is 4.0 [A / m ² ]. Even if the current applied to one anode 3 so as to be about 4.4 to 4.8 [A], no current is distributed in the back corner of the recess 1Ya of the steel sheet pile 1Y, and the current density distribution varies as described above. Is getting bigger.

  Subsequently, as shown in FIG. 6A, the pitch in the width direction of the concave portion 1Ya and the convex portion 1Yb of the steel sheet pile 1Y in the U-shaped connection model is P = 40 [cm] (the innermost portion of the concave portion 1Ya and the convex portion 1Yb). The steel sheet pile 1Y having a trapezoidal shape with a depth of D = 30 [cm] and a depth of D = 30 [cm] is 40 × 20 × 1. In order to install on the end face regarded as the quay of the analysis area of [m] and to consider the superposition of currents by the respective anodes 3, the five concave portions 1 </ b> Ya at the central portion in the width direction of the steel sheet pile 1 </ b> Y A model in which the anode 3 is arranged is created, and the overhang amount s of the anode 3 is set to 0, 10, 20, while the inter-electrode distance c is fixed to 5 [cm] based on the analysis result (see FIG. 5). When changed under six conditions of 30, 40, 50 [cm], three concave portions 1Ya and two convex portions 1Yb (FIG. 6). In (a), the evaluation of the uniformity of energization was performed by observing the maximum and minimum values and the distribution of the current density in the area surrounded by the phantom line.

In this U-shaped connection model, when the overhang s is 0, 10, 20 [cm], the maximum value of the current density in the steel sheet pile 1Y is 4.0 [A / m ² ] Even if the current applied to one anode 3 so as to be about 5.0 to 5.4 [A], the current density of the concave portion 1Ya (back surface and both side surfaces) and the convex portion 1Yb of the steel sheet pile 1Y in the evaluation range Although the variation in distribution is large, when the protruding amount s of the anode 3 is set to 30 [cm] or more, the maximum value of the current density in the steel sheet pile 1Y is about 4.0 [A / m ² ]. As can be seen, when the current applied to one anode 3 is 5.4 to 5.6 [A], the result shows that the range of the amplitude range of the maximum and minimum values of the current density does not change much. Therefore, in view of the quantity surface, it is considered optimal to set the protruding amount s of the anode 3 to 30 [cm] from the convex portion 1Yb of the steel sheet pile 1Y.

As described above, in both the Z-shaped connection model and the U-shaped connection model, the inter-electrode distance c between the three surfaces of the front surface 3a and both side surfaces 3b of the anode 3 and the inner surface of the recess 1Ya of the steel sheet pile 1Y is 5 [ in the state where the projecting amount s of both side surfaces 3b of the anode 3 from the concave portion 1Ya for passing an electric current to the surface of the convex portion 1Yb of the steel sheet pile 1Y is maintained at 30 [cm] or more. It is preferable to energize between the anode 3 and the steel sheet pile 1Y. Under this optimum condition, the current density on the surface of the submerged portion 2 of the steel sheet pile 1Y is within a range of 2.5 to 4.0 [A / m ² ], The simulation result that the anti-corrosion electrodeposition coating 5 (refer FIG. 18) of uniform thickness was formed on the surface of the steel sheet pile 1Y was obtained.

  However, since the above simulation results do not necessarily match the actual steel sheet pile 1Y of 1/1 scale, create a 1/2 scale steel sheet pile 1Y of the Z-shaped connection model shown in FIGS. Actual measurement by actual test and 1/2 scale simulation were performed, and it was verified whether each result matched.

  As shown in FIG. 7, seawater is poured into a container having a width of 134 [cm], a depth of 93 [cm], and a depth of 21 [cm] by an internal method to a depth of about 70%. And the width direction pitch of the convex portion 1Yb is P = 40/2 = 20 [cm], and the depth is D = 34/2 = 17 [cm]. SS400) and an aluminum anode 3 having a rectangular cross section are disposed in the recess 1Ya of the steel sheet pile 1Y, and a DC power source (20 [A], 12) not shown between the anode 3 and the steel sheet pile 1Y is disposed. When [V]) is connected and the inter-electrode distance c is changed, the variation of the overvoltage distribution at a plurality of locations on the inner surface of the recess 1Ya is measured while a simulation is performed. Since the variation in current density is equivalent to the variation in overvoltage (potential) distribution, the difference between the maximum value and the minimum value in the overvoltage distribution was used as an index for variation.

  As shown in the plot diagram of FIG. 8, the relationship between the inter-electrode distance c and the variation of the overvoltage distribution in the Z scale coupled model of 1/2 scale shown in FIG. 7 is substantially proportional in both the actual measurement and the simulation. Yes, it was confirmed that the results of actual measurement and simulation matched. That is, it is expected that the simulation results can be sufficiently used for the actual steel sheet pile 1Y of 1/1 scale. In the Z scale connected model of 1/2 scale shown in FIG. 7, it is considered effective to keep the distance c between the electrodes at 3 [cm] or less in order to suppress the variation in the overvoltage distribution. Considering that the distance c between the poles of an actual steel sheet pile 1Y of one scale is kept at 5 [cm] or less, the distance c between the poles in both the Z-shaped connection model and the U-shaped connection model is According to the conclusion that c ≦ 0.05 × (P + 2D) can be derived according to the width direction pitch P of the concave portion 1Ya and the convex portion 1Yb of the steel sheet pile 1Y to be connected and the depth D between the concave portion 1Ya and the convex portion 1Yb. It came. However, in actual construction, it is technically difficult to make the inter-electrode distance c as close to zero as possible because of the problem that the anode 3 is in contact with the steel sheet pile 1Y. Since it has been confirmed that there is no fear of the anode 3 coming into contact with the steel sheet pile 1Y even if c is narrowed to 1 [cm], the lower limit of the inter-electrode distance c is set to 1 [cm], and 1 ≦ c ≦ It may be 0.05 × (P + 2D). In addition, since there is no steel sheet pile of a standard that satisfies 0.05 × (P + 2D) ≦ 1, this equation is established.

  Similarly, as shown in FIG. 9, seawater is poured into a container having a width of 134 [cm], a depth of 93 [cm], and a depth of 21 [cm] by an internal method to a depth of approximately 70%, In addition, the concave and convex portions 1Ya and the convex portions 1Yb have a width direction pitch of P = 40/2 = 20 [cm] and a depth of D = 34/2 = 17 [cm]. (The material is SS400) and an aluminum anode 3 having a rectangular cross section is disposed in the recess 1Ya of the steel sheet pile 1Y, and a DC power source (20 [A] is not shown between the anode 3 and the steel sheet pile 1Y. , 12 [V]), and when the overhang amount s of the anode 3 is changed in a state where the distance c between the electrodes is fixed without being changed, the plurality of inner surfaces of the concave portion 1Ya and the convex portions 1Yb While actually measuring the variation of the overvoltage distribution at multiple locations on the surface, simulation was performed. The inter-electrode distance c was set to 0.05 × (20 + 2 × 17) = 2.7≈3 [cm] based on the formula 1 ≦ c ≦ 0.05 × (P + 2D).

The relationship between the overhanging amount s of the anode 3 and the variation in the overvoltage distribution in the 1/2 scale Z-shaped connection model shown in FIG. 9 is shown in the plot diagram of FIG. If it is less than cm], the variation in the overvoltage distribution decreases with an increase in the overhang amount s of the anode 3, and if the overhang amount s of the anode 3 is 14 [cm] or more, the variation in the overvoltage distribution does not change. It was confirmed that the results of each were consistent. That is, it is expected that the simulation results can be sufficiently used for the actual steel sheet pile 1Y of 1/1 scale. In the 1/2 scale Z-shaped connection model shown in FIG. 9, it is considered effective to keep the overhang amount s of the anode 3 at 14 [cm] or more in order to suppress the variation in the overvoltage distribution. In consideration of maintaining the protruding amount s of the anode 3 at 30 [cm] or more with respect to the actual steel sheet pile 1Y of 1/1 scale, both the Z-shaped connection model and the U-shaped connection model It came to the conclusion that the overhang amount s of 3 can be derived from the equation 0.75 × D ≦ s according to the depth D between the concave portion 1Ya and the convex portion 1Yb of the steel sheet pile 1Y connected and arranged. However, in actual construction, it is not only unnecessary to lengthen the protruding amount s of the anode 3 as much as possible. In the case of a U-shaped connection model, there is a problem that the anodes 3 adjacent to each other come into contact with each other. Because it occurs, it is necessary to decide the upper limit. Although the protruding amount s of the anode 3 varies depending on the shape of the steel sheet pile 1Y, the adjacent anodes 3 are most likely to come into contact with each other in the recesses 1Ya and the projections 1Yb of the steel sheet piles 1Y that are connected and arranged. This is a case where the steel sheet pile 1Y whose inclination is the most gradual in the standard is targeted. Equivalent to. Incidentally, the shape of the hat-type steel sheet pile can be considered to be substantially the same as that of the U-shaped connection model, except that the joint position and the assembly method are different. In the steel sheet pile 1Y of the type NSP-10H, as shown in FIG. 11, the pitch in the width direction of the concave portion 1Ya and the convex portion 1Yb is P = 45 [cm], the depth is D = 23 [cm], and the convex portion 1Yb Since the width is 32.2 [cm] and the opening width of the recess 1 Ya is 57.8 [cm], when the inter-electrode distance c is reduced to 1 [cm], the dimensional relationship of the trapezoidal anode 3 is
(22 + s): 22 = ((90-30.2) / 2): ((55.8-30.2) / 2)
(22 + s): 22 = 29.9: 12.8
The overhang amount s when the adjacent anodes 3 are in contact with each other is
s = 29.4 [cm]
It becomes. When this is expressed with reference to the depth D of the steel sheet pile 1Y,
s = 1.278 × D
Therefore, as the upper limit value of the overhang amount s of the anode 3,
s ≒ 1.25 × D
If so, even if applied to any steel sheet pile 1Y specified in at least "steel pipe pile and steel sheet pile technology association", there will be no problem that the adjacent anodes 3 contact each other, The range of the overhang s of the anode 3 may be 0.75 × D ≦ s ≦ 1.25 × D. In addition, in the case of the steel sheet pile 1Y of the Z-shaped connection model, even if the protruding amount s of the anode 3 is made as long as possible, the adjacent anodes 3 do not come into contact with each other. Let the amount be s.

  As described above, the formula 1 ≦ c ≦ 0.05 × (P + 2D) relating to the inter-electrode distance c and the formula 0.75 × D ≦ s ≦ 1.25 × D relating to the overhang amount s of the anode 3 are connected, although there are errors. Corrosion-proof electrodeposition with a uniform thickness on the surface of the steel sheet pile 1Y according to the width direction pitch P of the concave portion 1Ya and the convex portion 1Yb of the steel sheet pile 1Y and the depth D between the concave portion 1Ya and the convex portion 1Yb. It can serve as an index for forming the film 5.

  On the other hand, the material of the anode 3 may be either soluble or insoluble. If possible, a general insoluble material used in harbors is preferable. However, considering the consumed amount during energization, such as setting the inter-electrode distance c narrow and preventing the anode 3 from collapsing. Thus, when the anode 3 is formed, a soluble material may be used.

The shape of the anode 3 can be trapezoidal and solid as shown in FIG. 12 (a). However, since only the surface shape is important for the shape of the anode 3, FIG. As shown in FIG. 4, a trapezoidal and hollow anode 3 may be used. If such an anode 3 is used, it is considered that the construction can be facilitated by weight reduction. It is also possible to use the anode 3 having a network structure as shown in FIG. Furthermore, in the U-shaped connection model shown in FIG. 6A, the current density distributions of the upper base surface and the lower base surface of the trapezoidal anode 3 were compared, and as a result, The current density is 3 to 5 [A / m ² ], and the current density of the lower bottom surface is about 0.5 [A / m ² ], which flows roughly to the lower bottom surface of the anode 3. Since the current is considered to be about 10% of the entire area of the anode 3, the bottom surface is not necessarily required. As shown in FIG. 12D, the U-shaped shape with the trapezoidal bottom surface removed. Anode 3, that is, an anode 3 having at least three surfaces of a front surface 3a and both side surfaces 3b facing each other so as to follow the inner surface of the recess 1Ya of the steel sheet pile 1Y can be used. In the case of the steel sheet pile 1Y of the U-shaped connection model, strictly speaking, as shown in FIG. 1, since a step is generated in the connecting portion, the shape of the tip portion of the anode 3 is set so as to follow the step. A shape indicated by an imaginary line may be used. Moreover, as shown in FIG. 4, the anode 3 used for the steel sheet pile 1Y of the Z-shaped connection model has a rectangular cross section, but, like the anode 3 having a trapezoidal cross section shown in FIG. 12, a solid, hollow, mesh structure, Any of the U-shapes can be selected.

  Further, the surface of the anode 3 facing the steel sheet pile 1Y may be a flat plate, but it should have a mesh shape as shown in FIG. 13 (a) or a perforated shape as shown in FIG. 13 (b). Thus, drag to the anode 3 due to waves and the weight of the anode 3 can be reduced.

  In the present embodiment, since the distance c between the poles between the three surfaces of the front surface 3a and both side surfaces 3b of the anode 3 and the inner surface of the recess 1Ya of the steel sheet pile 1Y is very small, the anode 3 is moved to the steel sheet pile 1Y by rocking due to waves. It is necessary to fix the anode 3 so as not to contact and short-circuit. Therefore, as shown in FIGS. 14 (a) and 14 (b), an installation bar 6 extending from the quay side to the sea is provided, and the anode 3 is attached to the fixing bar 7 suspended from the installation bar 6, A holding means 9 for the anode 3 is configured by attaching a weight 8 that sinks to the sea bottom to the lower end of the fixing bar 7.

  When the anode 3 is arranged with respect to the steel sheet pile 1Y by the holding means 9, for example, as shown in FIG. 15, the anode 3 integrated with a fixing bar 7 having a weight 8 attached to the lower end is prepared in advance. While the anode 3 is moved / adjusted to the steel sheet pile 1Y side, the upper end of the fixing bar 7 is connected and fixed to the installation bar 6 protruding from the quay, or as shown in FIG. The bar 6, the fixing bar 7, the anode 3 and the weight 8 are previously integrated, and the installation bar 6 is fixed to the quay while moving and adjusting the whole to the steel sheet pile 1 Y side. be able to.

  It is also possible to energize the anode 3 without using a power line by using aluminum or the like for the installation bar 6 and the fixing bar 7.

  Of course, it is possible to arrange the anodes 3 one by one with respect to the respective recesses 1Ya of the steel sheet pile 1Y by means of the holding means 9, but in order to improve the construction efficiency, for example, as shown in FIG. It is also possible to install the anode 3 at a time for the plurality of recesses 1Ya by creating a set of the anode 3 in a set with the installation bar 6 and the fixing bar 7 of the holding means 9. is there.

  In this embodiment, as described above, the holding means 9 causes the distance c between the three surfaces of the front surface 3a and both side surfaces 3b of the anode 3 and the inner surface of the recess 1Ya of the steel sheet pile 1Y to be 1 ≦ c ≦ 0.05 × ( P + 2D), and the overhang amount s of both side surfaces 3b of the anode 3 from the concave portion 1Ya for flowing current to the surface of the convex portion 1Yb of the steel sheet pile 1Y is maintained at 0.75 × D ≦ s ≦ 1.25 × D. In this state, when an electric current is applied between the anode 3 and the steel sheet pile 1Y, the electrode 3 is electrodeposited using an electrode of a general shape such as a round bar or a plate as the anode 3 as in the past. In contrast, even if the steel sheet pile 1Y has an uneven shape, a difference in the amount of electricity is less likely to occur, and the thickness of the anticorrosion electrodeposition coating 5 (see FIG. 18) formed on the surface of the steel sheet pile 1Y varies greatly. Can be avoided.

  Thus, the anticorrosion electrodeposition coating 5 having a uniform thickness can be formed on the surface of the steel sheet pile 1Y.

In addition, the electrodeposition anticorrosion apparatus of the steel sheet pile of this invention is not limited only to the above-mentioned Example, Not only steel sheet piles, such as a Z-shaped connection model and a U-shaped connection model, but a U-shaped connection model. Needless to say, various modifications can be made without departing from the gist of the present invention, such as being applicable to a so-called combination type steel sheet pile welded face to face.

DESCRIPTION OF SYMBOLS 1 Marine steel structure 1Y Steel sheet pile 1Ya Concave part 1Yb Convex part 2 Submerged part 3 Anode 3a Front surface 3b Side surface 4 DC power supply 5 Anticorrosion electrodeposition coating 6 Installation bar 7 Fixing bar 8 Weight 9 Holding means P Width direction pitch D Depth c Distance between electrodes s Overhang

Claims (1)

An anode is provided at a required interval with respect to the submerged portion of the steel sheet pile that is connected and arranged so that the uneven portion is formed, and a direct current is applied by providing a DC power source between the anode and the steel sheet pile. In the electrodeposition anticorrosion device of the steel sheet pile that forms an anticorrosion electrodeposition coating on the surface of the submerged portion of the steel sheet pile,
An anode having at least three front and both side surfaces facing the concave inner surface of the steel sheet pile,
When the pitch in the width direction of the recesses and projections of the steel sheet piles to be connected is P [cm] and the depth between the recesses and projections is D [cm], the front and both sides of the anode The distance c [cm] between the electrode and the inner surface of the concave portion of the steel sheet pile
1 ≦ c ≦ 0.05 × (P + 2D)
And projecting amounts s [cm] of both side surfaces of the anode from the concave portion for allowing an electric current to flow through the convex surface of the steel sheet pile.
0.75 × D ≦ s ≦ 1.25 × D
And a holding means for holding the,
The holding means includes an installation bar provided so as to project from the quay side to the sea, a fixing bar suspended from the installation bar and attached with an anode, and attached to a lower end of the fixing bar and sinking to the seabed A plurality of anodes are combined into a set with a holding bar and a fixing bar for the holding means, and the anodes are installed at a time for a plurality of recesses. electrodeposition anticorrosion device of a steel sheet pile, characterized in that the.

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