Soundness inspection device and soundness inspection method of PC steel rod used for floating body in floating offshore wind power generation installation

Abstract

To enable inspection of soundness over the whole length, in a PC steel rod of a floating body of a floating offshore wind power generation installation.SOLUTION: A floating offshore wind power generation installation includes a concrete floating body part 4A which is formed by plurally staking concrete precast cylindrical bodies 15 in a height direction so as to integrally binding each of the precast cylindrical bodies 15 with PC steel rods 19. A soundness inspection device 1 is for the PC steel rods 19 used for the concrete floating body part 4A in the floating offshore wind power generation installation. The soundness inspection device 1 includes: vibration sensors 31 attached to the PC steel rods 19; an oscillator 32 which is attached to the upper end of the PC steel rod 19 so as to input an elastic wave into the PC steel rod 19; and a detector 33 for transmitting signals measured by the vibration sensors 31.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for inspecting the soundness of PC steel bars in a floating offshore wind power generation facility, which includes a float having concrete precast cylindrical bodies stacked vertically in multiple tiers and each precast cylindrical body fastened and integrated with PC steel bars. [Background technology]

[0002] Traditionally, hydroelectric, thermal and nuclear power generation have been the main power generation methods used, but in recent years, wind power generation, which uses natural wind to generate electricity, has been attracting attention from the perspective of the environment and the effective use of natural energy. Wind power generation facilities can be installed on land or on water (mainly offshore), but in Japan, which has mountainous terrain behind its coasts, there are few plains in coastal areas where stable winds can be expected. On the other hand, Japan is surrounded by sea on all sides, and has the advantage that winds suitable for generating electricity can be easily obtained on the sea and there are fewer restrictions on installation. For this reason, many different types of offshore wind power generation facilities and floating structures have been proposed in recent years.

[0003] The floating structure can be broadly classified into a barge type float, which floats on the water surface, a semi-submersible type, in which the lower part of the float is submerged below the water surface to float in a semi-submerged state, and a spar type, which floats in an upright position like a fishing float.

[0004] With regard to the spar-type float, the applicant has proposed in Patent Document 1 listed below an offshore wind power generation facility consisting of a float, mooring lines, a tower, and a nacelle and multiple wind turbine blades installed at the top of the tower, wherein the float is an offshore wind power generation facility with a spar-type floating structure consisting of a lower concrete floating structure part (hereinafter referred to as the concrete floating structure part) in which concrete precast cylindrical bodies are stacked vertically in multiple tiers and fastened together with PC steel bars to form an integrated body, and an upper steel floating structure part (hereinafter referred to as the steel floating structure part) connected to the upper side of the concrete floating structure (hereinafter referred to as the steel floating structure part).

[0005] The PC steel rods that fasten the precast cylindrical bodies in the concrete floating body section are important strength members, and therefore it is extremely important to ensure their soundness.

[0006] Conventionally, the following methods have been known as non-destructive inspection methods for inspecting the soundness of PC steel bars.

[0007] As disclosed in the following Patent Document 2, an ultrasonic method is used to inspect the degree of corrosion of reinforcing bars in a concrete structure by placing a transmitting probe and a receiving probe apart from each other on reinforcing bars in reinforced concrete, transmitting ultrasonic waves from the transmitting probe, and receiving the propagated waveform at the receiving probe. As disclosed in the following Patent Document 3, a magnetic stream method is used in which a magnetic field is applied to a measurement object such as a steel material contained in a concrete structure by a magnetic field application unit, a magnetic flow path is formed in the measurement object, and the magnetic field leaking out from the measurement object is measured by a magnetic sensor. As disclosed in Patent Document 4 below, this is a radiographic method in which an X-ray generator and film are placed on both sides of a concrete structure, X-rays are irradiated onto one side of the concrete structure, and an X-ray image of the concrete structure is taken on film. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5274329 [Patent Document 2] JP 2008-2923 A [Patent Document 3] WO2020 / 027028 publication [Patent Document 4] Special Publication No. 2-42408 Summary of the Invention [Problem to be solved by the invention]

[0009] However, with the ultrasonic method, the maximum distance that ultrasonic waves can transmit is short, at a few meters, and the signal does not reach the floating PC steel rods in floating offshore wind power generation facilities, which have a total length of several tens of meters, so measurements cannot be made over the entire length.In addition, ultrasonic waves have the property of being reflected by obstacles in the way, so in the case of PC steel rods connected by couplers, they are reflected at the connections, making it impossible to measure the entire length.

[0010] In the magnetic stream method, the maximum distance at which the magnetic sensor can measure the magnetic field leaking from the object is only about 200 mm, making it unsuitable for inspecting large structures such as the floats in floating offshore wind power generation facilities. In addition, the inside of the float is filled with ballast water, making it impossible to measure from the side.

[0011] In addition, the radiographic method requires a development process for the X-ray film, which takes a long time for the inspection, and requires special equipment such as film for taking X-ray images, which increases costs.In addition, since the inside of the floating structure is filled with ballast water, it is impossible to measure from the side.

[0012] Therefore, the main object of the present invention is to provide a soundness inspection device and a soundness inspection method that enable the easy inspection of the soundness over the entire length of the PC steel bars of the floats in floating offshore wind power generation facilities. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention according to claim 1 provides a float in a floating offshore wind power generation facility, the float being made of concrete precast cylindrical bodies stacked in a height direction in a number of stages and each precast cylindrical body being fastened and integrated with a PC steel bar, the float comprising: There is provided a soundness inspection device for PC steel bars used in floats in floating offshore wind power generation facilities, characterized by comprising a vibration sensor attached to the PC steel bar, an oscillator attached to the upper end of the PC steel bar and inputting elastic waves into the PC steel bar, and a detection unit to which the signal measured by the vibration sensor is transmitted.

[0014] In the invention described in claim 1, a vibration sensor is attached to, for example, the lower end of the PC steel rod, and an oscillator is attached to the upper end of the PC steel rod, and the vibration transmission state of the PC steel rod when elastic waves are input by the oscillator is measured by the vibration sensor. If there is an abnormality in the vibration waveform measured by the vibration sensor, it can be determined that there is an abnormality such as a break in the PC steel rod, and the soundness of the PC steel rod over its entire length can be easily inspected.

[0015] The present invention according to claim 2 provides a soundness inspection device for PC steel bars used in a float in a floating offshore wind power generation facility as described in claim 1, in which the vibration sensor is configured to fix a sensor unit including a circulating part around a part of an optical fiber to a measured part and to detect a frequency change between input light and output light that has passed through the circulating part.

[0016] In the invention described in claim 2, a FOD (Fiber Optical Doppler) sensor is used as the vibration sensor. This FOD sensor is made of optical fiber and has no electrical components, making it suitable for use in environments such as offshore.

[0017] As a third aspect of the present invention, the vibration sensor is a piezoelectric sensor, A plurality of the piezoelectric sensors are connected by electric wires, and the electric wires extend to the detection unit, There is provided a soundness inspection device for PC steel bars used in a float in a floating offshore wind power generation facility as recited in claim 1, wherein the detection unit has a switching function for switching in sequence the PC steel bars to be measured.

[0018] In the invention described in claim 3, by using a piezoelectric sensor as the vibration sensor, the vibration sensors attached to each PC steel bar can be connected with an electric wire, and the number of wires extending from the PC steel bar to the detection unit can be minimized. During measurement, the PC steel bar to be measured is switched in order by a switching function provided in the detection unit.

[0019] The present invention according to claim 4 provides a soundness inspection device for PC steel bars used in a float in a floating offshore wind power generation facility as described in claim 1, wherein the oscillator device emits a chirp wave whose frequency changes over time.

[0020] In the invention described in claim 4, chirp waves that can increase the output intensity at any position are used as the elastic waves oscillated from the oscillator, which makes it possible to inspect the PC steel bars for abnormalities for each precast cylindrical body.

[0021] The present invention according to claim 5 provides a method for inspecting the soundness of PC steel bars used in a float in a floating offshore wind power generation facility, the float being made of a concrete precast cylindrical body stacked in a plurality of layers in the height direction and each precast cylindrical body fastened and integrated with a PC steel bar, the method comprising: A step of attaching a vibration sensor to a lower end of the PC steel rod during construction of the floating body; After the floating offshore wind power generation facility starts operating, a step of attaching an oscillator to an upper end of the PC steel rod for inputting elastic waves into the PC steel rod; The present invention provides a method for inspecting the soundness of PC steel bars used in floats in floating offshore wind power generation facilities, the method comprising the steps of: when elastic waves are input to the PC steel bars by the oscillator device, a signal measured by the vibration sensor is transmitted to a detection unit, and the soundness of the PC steel bars is evaluated.

[0022] In the invention described in claim 5 above, the vibration sensor is attached in advance when the float is constructed, and after the floating offshore wind power generation equipment starts operation, vibrations are measured by inputting elastic waves into the PC steel rods using the oscillator device.

[0023] According to a sixth aspect of the present invention, there is provided a method for inspecting the soundness of PC steel bars used in floats in floating offshore wind power generation facilities, in which the oscillators are replaced and measurements are performed sequentially.

[0024] In the invention described in claim 6 above, instead of installing an oscillator on every PC steel rod, one or more oscillators are used and these are replaced one after another for measurement, thereby reducing equipment costs. Effect of the Invention

[0025] As explained above in detail, according to the present invention, it becomes possible to easily inspect the soundness of the PC steel bars of the floats in a floating offshore wind power generation facility over their entire length. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is an overall view of a spar-type offshore wind power generation facility 1. [Diagram 2] FIG. [Diagram 3] 1 shows a precast cylindrical body 15, in which (A) is a longitudinal cross-sectional view, (B) is a plan view (viewed in the direction of the arrow BB), and (C) is a bottom view (viewed in the direction of the arrow CC). [Figure 4] 1A and 1B are diagrams showing how precast cylindrical bodies 15 are fastened together. [Diagram 5] 1 is an enlarged vertical cross-sectional view showing the boundary between a concrete floating body portion 4A and a steel floating body portion 4B. [Figure 6] 1 is a vertical cross-sectional view of a concrete floating body section 4A, showing a soundness inspection device 30 according to the present invention. [Figure 7] 1 is a bottom view of the lower end of the PC steel bar 19. FIG. [Figure 8] FIG. 11 is a vertical cross-sectional view of a concrete floating body section 4A, showing a soundness inspection device 30 according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. [Hybrid spar-type offshore wind power generation facility 1] First, a spar-type offshore wind power generation facility 1 to which the present invention is applied will be described in detail with reference to Figs. 1 to 5.

[0028] As shown in detail in Figure 1, the spar-type offshore wind power generation facility 1 is composed of a spar-type cylindrical floating body 4, mooring lines 10, a tower 6, and a wind turbine 7 consisting of a nacelle 8 installed on the top of the tower 6 and a number of blades 9, 9...

[0029] As shown in FIG. 2, the float 4 comprises a concrete floating section 4A in which concrete precast cylindrical bodies 15, 15... are stacked vertically in multiple stages and each precast cylindrical body 15, 15... is fastened together with PC steel rods 19 to form an integrated body, and a steel floating section 4B connected to the upper side of this concrete floating section 4A.

[0030] Ballast materials such as water, gravel, fine aggregate, coarse aggregate, and metal particles can be charged or discharged into or from the hollow portion of the floating body 4, making the buoyancy (draft) adjustable. The charging / discharging of ballast materials is possible by employing the fluid transport method previously proposed by the applicant in JP 2012-201217 A.

[0031] The concrete floating section 4A is composed of concrete precast cylindrical bodies 15, 15.... As shown in Fig. 3, the precast cylindrical bodies 15 are circular cylindrical precast members having the same cross section in the axial direction, and each is manufactured using the same formwork, or a hollow precast member manufactured by centrifugal molding is used.

[0032] In addition to the reinforcing bars 20, sheaths 21, 21... for inserting the PC steel bars 19 are embedded in the wall surface at appropriate intervals in the circumferential direction. The lower ends of these sheaths 21, 21... are formed with sheath enlarged diameter sections 21a so that couplers for connecting the PC steel bars 19 can be inserted, and the upper sections are formed with box-opening sections 22 for fitting in anchor plates for fixing. In addition, multiple hanging fittings 23 are provided on the upper surface.

[0033] As shown in Fig. 4(A), the precast cylindrical bodies 15 are joined together by stacking the precast cylindrical bodies 15, 15 while inserting the PC steel bars 19, 19... extending upward from the lower precast cylindrical body 15 into the sheaths 21, 21..., and then fitting the anchor plate 24 into the box-opening portion 22 and introducing tension into the PC steel bars 19 with the nut member 25 to integrate the precast cylindrical bodies 15. Furthermore, grout material is injected into the sheath 21 from the grout injection hole 27. The hole 24a formed in the anchor plate 24 is a grout injection confirmation hole, and the filling of the grout material is completed when the grout material is discharged from the confirmation hole.

[0034] 4(B), couplers 26 are screwed onto the protruding parts of the PC steel bars 19 to connect the upper PC steel bars 19, 19..., and the PC steel bars 19, 19... are then inserted into the sheaths 21, 21... of the upper precast tubular body 15 while being stacked, and the procedure of fixing the PC steel bars 19 in the above manner is repeated in order to stack them up vertically. At this time, an adhesive 28 such as an epoxy resin-based adhesive or sealant is applied to the joint surfaces between the lower precast tubular body 15 and the upper precast tubular body 15 to ensure watertightness and to bond the mating surfaces.

[0035] The steel floating body section 4B is composed of a steel cylindrical body 17 located relatively on the lower side, and a steel cylindrical body 18 located relatively on the upper side. The lower part of the steel cylindrical body 17 on the lower side has the same outer diameter as the precast cylindrical body 15, and as shown in Figure 5, it is connected to the precast cylindrical body 15 by bolts or welding (bolt fastening is shown in the illustrated example). The upper part of the steel cylindrical body 17 forms a truncated cone shape with a gradually narrowing diameter.

[0036] The upper steel cylindrical body 18 is a cylindrical body with an outer diameter dimension that is continuous with the upper outer diameter of the lower steel cylindrical body 17, and is connected to the lower steel cylindrical body 17 by bolts or welding or the like (bolt fastening is shown in the illustrated example). These steel cylindrical bodies 17, 18 are composed of steel rings divided for each predetermined weight, and the steel rings are integrated by welding in the circumferential direction.

[0037] On the other hand, the tower 6 is made of steel, concrete or PRC (prestressed reinforced concrete), but it is preferable to use one made of steel so that the total weight is small. The outer diameter of the tower 6 and the outer diameter of the upper steel cylindrical body 18 are almost the same, and the outer shape is continuous in the vertical direction without any steps.

[0038] As shown in Fig. 1, the mooring point P of the mooring line 10 to the float 4 is set below the sea surface and at a position higher than the center of gravity G of the float 4. This makes it possible to prevent a ship from coming into contact with the mooring line 10. Also, since a resistance moment is generated around the center of gravity G of the float 4 at the mooring point P so as to prevent the float 4 from tipping over too much, the tilting attitude of the tower 6 can be appropriately maintained.

[0039] On the other hand, the nacelle 8 is a device equipped with a generator that converts the rotation of the wind turbine 7 into electricity, a controller that can automatically change the angle of the blades 9, and the like. [Soundness inspection device 30] Next, a soundness inspection device 30 for the PC steel rods 19 used in the float 4 (concrete float portion 4A) in the above-mentioned hybrid spar type offshore wind power generation facility 1 will be described.

[0040] 6, the soundness inspection device 30 is composed of a vibration sensor 31 attached to the PC steel rod 19, an oscillator 32 attached to the upper end of the PC steel rod 19 and inputting elastic waves into the PC steel rod 19, and a detection unit 33 to which a signal measured by the vibration sensor 31 is transmitted. The vibration sensor 31 may be attached at any position such as the lower end or upper end of the PC steel rod 19, or at one location along the way or at multiple locations spaced apart, but in this embodiment, the vibration sensor 31 is attached to the lower end of the PC steel rod 19.

[0041] As the vibration sensor 31, any known vibration sensor can be used without restriction as long as it can detect the vibration transmitted to the lower end of the PC steel rod 19 when a high-frequency elastic wave is input to the upper end of the PC steel rod 19.

[0042] In particular, it is desirable to use an FOD (Fiber Optical Doppler) sensor disclosed in WO2003 / 002956 as the vibration sensor 31. The FOD sensor disclosed in this publication is a sensor configured to fix a sensor unit including a circumferential portion in which a part of an optical fiber is circumferentially wound to a part to be measured, and to detect a frequency change between input light and output light that has passed through the circumferential portion. This FOD sensor has the advantages of being usable in environments such as offshore because it has no electrical components, and being able to perform measurements for a long period of time because it uses highly durable optical fiber.

[0043] When an FOD sensor is used as the vibration sensor 31, the sensor unit is attached to the lower end of each PC steel rod 19, and an optical fiber 34 is extended in the vertical direction (axial direction) on the inner surface of the precast cylindrical bodies 15, 15... near the PC steel rod 19. The optical fiber 34 is connected to an input unit that inputs coherent light to the optical fiber 34, and to the detection unit 33. The detection unit 33 is configured to detect the vibration applied to the circulating portion by detecting a frequency change between the input light and the output light that has passed through the circulating portion.

[0044] When the optical fiber 34 is arranged along the inner surface of the precast cylindrical bodies 15, 15..., in order to prevent the optical fiber 34 from being damaged by the ballast material poured into the hollow interior of the floating body, it is preferable to protect the optical fiber 34 by fitting a protective tube such as a steel pipe around it, at least within the height range where the ballast material is filled.

[0045] On the other hand, a piezoelectric sensor using a ceramic element can be used as the vibration sensor 31. When a piezoelectric sensor is used as the vibration sensor 31, as in the case of the FOD sensor, as shown in FIG. 7(A), an electric wire 35 connected to the piezoelectric sensor may be extended in the vertical direction on the inner surface of the precast cylindrical body 15, 15 ... near the PC steel bar 19, or as shown in FIG. 7(B), a plurality of piezoelectric sensors may be connected to the electric wire 35 at the lower end of the PC steel bar 19, and the electric wire 35 connected to the plurality of piezoelectric sensors may be extended in the vertical direction (axial direction) on the inner surface of the precast cylindrical body 15, 15 .... By disposing one electric wire 35 for the plurality of piezoelectric sensors shown in FIG. 7(B) along the inner surface of the floating body, the number of electric wires 35 extended in the vertical direction can be reduced to the minimum necessary number, such as 1 to 2. An electric wire 35 extending from the piezoelectric sensor is connected to the detection unit 33, and in this detection unit 33, switching is performed to sequentially switch the PC steel rod 19 to be measured.

[0046] The oscillator 32 is a device that inputs high-frequency elastic waves to the upper end of the PC steel rod 19 by means of electromagnetic pulses.

[0047] The oscillator 32 does not need to be installed on all of the PC steel rods 19, and after the measurement of one PC steel rod 19 is completed, it can be replaced with the oscillator 32 for the adjacent PC steel rod 19 and measurements can be performed in sequence. This makes it possible to reduce the equipment costs required for measurement.

[0048] The elastic wave input by the oscillator 32 is preferably a wave generated by combining multiple arbitrary frequencies. Since the elastic wave generated by the electromagnetic pulse is attenuated when the transmission distance is long, such as between the upper and lower ends of the PC steel rod 19, the signal strength is increased at a specific arbitrary position even with low output to concentrate the elastic wave and improve the measurement accuracy, so that an elastic wave combining multiple frequencies corresponding to this position is input.

[0049] A chirp wave, the frequency of which changes over time, is more preferable as the elastic wave oscillated from the oscillator 32. By oscillating a chirp wave, it is possible to easily increase the signal strength at any point, and it is also possible to inspect each precast cylindrical body 15 for abnormalities in the PC steel rods.

[0050] The detection unit 33 receives the signal measured by the vibration sensor 31, calculates the vibration of the lower end of the PC steel bar 19, and stores and accumulates the data.

[0051] When an FOD sensor is used as the vibration sensor 31, as described above, the detection unit 33 detects the frequency change between the input light and the output light that has passed through the circulating portion, and detects the vibration applied to the circulating portion.

[0052] When a piezoelectric sensor is used as the vibration sensor 31, vibration data measured by the piezoelectric sensor is collected, stored, and accumulated in the detection unit 33. When multiple piezoelectric sensors are connected by electric wires 35 and one electric wire 35 extending therefrom is connected to the detection unit 33, the detection unit 33 has a switching function for switching in order the PC steel rod 19 to be measured.

[0053] [Soundness inspection method] Next, a procedure for inspecting the soundness of the PC steel bar 19 using the soundness inspection device 30 will be described.

[0054] First, when constructing the float 4 (concrete floating body portion 4A), a vibration sensor 31 is attached in advance to the lower end of the PC steel rod 19. When a concrete bottom is provided to close the bottom opening of the lowest precast cylindrical body 15, the vibration sensor 31 may be disposed in the space formed at and around the lower end of the PC steel rod 19, or may be embedded in the concrete bottom.

[0055] After the construction of the spar-type offshore wind power generation facility 1 is completed and the facility begins operation, regular inspections of the integrity of the PC steel bars 19 are performed to confirm that the PC steel bars 19 are sound. By performing soundness inspections, initial construction defects and deterioration over time can be discovered early and measures can be taken, reducing the impact on the overall maintenance schedule. In addition, it is possible to prepare in advance by identifying the timing of maintenance and arranging replacement parts, and such preventive maintenance leads to reduced maintenance costs, such as reducing the period of operation shutdown required for maintenance.

[0056] In the soundness inspection, the oscillator 32 is attached to the upper end of the PC steel bar 19, and when elastic waves are input to the PC steel bar 19 by the oscillator 32, the signal measured by the vibration sensor 31 is transmitted to the detection unit 33, and the soundness of the PC steel bar 19 is evaluated in the detection unit 33 or in an analysis device that analyzes the data transmitted from it. This inspection method is characterized by a clear criterion for judgment, since if the vibration sensor 31 cannot detect the transmitted waves, it is determined that the bar has broken along the way.

[0057] As for the oscillator 32, if the oscillator 32 installed on the PC steel rod 19 is replaced and measurements are performed sequentially, it will be sufficient to prepare one or at most several oscillators 32 for one spar-type offshore wind power generation facility 1.

[0058] [Other examples] In the above embodiment, the vibration sensor 31 is attached to the lower end of the PC steel rod 19, but as shown in Fig. 8, the vibration sensor 31 may be attached to the upper end of the PC steel rod 19. In other words, the oscillator 32 and the vibration sensor 31 are attached to the upper end of the PC steel rod 19.

[0059] For this measurement, elastic waves are input by an oscillator 32 attached to the upper end of the PC steel rod 19, and the reflected waves reflected at the lower end of the PC steel rod 19 are detected by the vibration sensor 31 attached to the upper end of the PC steel rod 19. In this case, the signal strength of the elastic waves input from the oscillator 32 must be increased in order to measure the reflected waves, so it is preferable that the elastic waves oscillated from the oscillator 32 be chirp waves that generate a concentrated wave at a desired point by superimposing elastic waves of a desired frequency to increase vibration strength. In this case, the point at which the concentrated chirp wave is generated is set at the lower end of the PC steel rod 19.

[0060] In this modified example, since the vibration sensor 31 is attached to the upper end of the PC steel rod 19, there is no need to attach the vibration sensor 31 in advance before constructing the floating body 4, and there is also no need to attach the vibration sensor 31 to all of the PC steel rods 19. Rather, by using one vibration sensor 31 and one oscillator 32 and attaching them to each PC steel rod 19 in turn, it is possible to inspect the soundness of all of the PC steel rods 19. [Explanation of symbols]

[0061] 1...Spar-type offshore wind power generation equipment, 4...Floating body, 4A...Concrete floating body section, 4B...Steel floating body section, 6...Tower, 7...Wind turbine, 8...Nacelle, 9...Blade, 10...Mooring line, 15...Precast cylindrical body, 19...PC steel rod, 30...Soundness inspection device, 31...Vibration sensor, 32...Oscillator, 33...Detection section, 34...Optical fiber, 35...Electric wire

Claims

1. A floating offshore wind power generation facility includes a float in which concrete precast cylindrical bodies are stacked in a plurality of layers in the height direction and each precast cylindrical body is fastened and integrated with a PC steel bar. The float is provided with a PC steel bar for inspecting the integrity of the PC steel bar, A soundness inspection device for PC steel bars used in floats in floating offshore wind power generation facilities, comprising: a vibration sensor attached to the PC steel bar; an oscillator attached to the upper end of the PC steel bar and inputting elastic waves into the PC steel bar; and a detection unit to which a signal measured by the vibration sensor is transmitted.

2. 2. The device for inspecting the soundness of PC steel bars used in a float in a floating offshore wind power generation facility as described in claim 1, wherein the vibration sensor is configured to fix a sensor unit including a winding portion around which a portion of an optical fiber is wound to the measured portion and to detect a change in frequency between input light and output light that has passed through the winding portion.

3. The vibration sensor is a piezoelectric sensor, A plurality of the piezoelectric sensors are connected by electric wires, and the electric wires extend to the detection unit, 2. The apparatus for inspecting the integrity of PC steel rods used in a float in a floating offshore wind power generation facility according to claim 1, wherein the detection unit has a switching function for switching the PC steel rods to be measured in sequence.

4. 2. The soundness inspection device for PC steel bars used in a float in a floating offshore wind power generation facility according to claim 1, wherein the oscillator generates a chirp wave whose frequency changes over time.

5. A method for inspecting the soundness of PC steel bars used in a float in a floating offshore wind power generation facility, the float being made of a concrete precast cylindrical body stacked in a plurality of layers in the height direction and each precast cylindrical body being fastened and integrated with a PC steel bar, comprising: A step of attaching a vibration sensor to the lower end of the PC steel rod during construction of the floating body; After the floating offshore wind power generation facility starts operating, a step of attaching an oscillator to an upper end of the PC steel rod for inputting elastic waves into the PC steel rod; a step of transmitting a signal measured by the vibration sensor to a detection unit when an elastic wave is input to the PC steel rod by the oscillator device, thereby evaluating the soundness of the PC steel rod.

6. A method for inspecting the soundness of PC steel bars used in floats in floating offshore wind power generation facilities, in which the oscillator is replaced and measurements are performed sequentially.

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