JP2018124109A - Crack detection system and crack detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crack detection system capable of improving the detection accuracy at a detection part formed of a conductive coating material.SOLUTION: The crack detection system for detecting a crack generated on a measurement object. The crack detection system includes: a detection part 3 which is formed of the conductive coating material so as to be easily broken; a conductor part 4 connected to the detection part; and a data collection part 5 connected to the conductor part. Plural rows of detection parts are formed in a detection area where cracks should be detected in the lower surface 12 of the girder of a PC girder 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a crack detection system and a crack detection method for detecting a crack generated in a measurement object.

  As disclosed in Patent Documents 1 and 2, there is known a method for detecting the occurrence of deformation such as cracks by applying a conductive paint to the surface of a concrete structure made of reinforced concrete.

  That is, an electric circuit is formed by applying a conductive paint to the surface of a concrete structure, and is detected when the electric circuit breaks due to the occurrence or expansion of cracks.

JP 2016-24139 A JP 2016-24138 A

  However, when a crack is detected by an electric circuit formed by applying a conductive paint, the detection error may be larger than that detected by a strain gauge or the like, and improvement in detection accuracy has been demanded.

  Then, this invention aims at providing the crack detection system and the crack detection method which can improve the detection accuracy of the detection part formed with an electrically conductive coating material.

  In order to achieve the above object, a crack detection system of the present invention is a crack detection system for detecting a crack generated in a measurement object, the detection unit formed in a state that is easily broken by a conductive paint, and the detection unit And a data collecting unit connected to the conducting wire part, wherein the detecting part is provided with a plurality of rows in a detection area where it is desired to detect cracks in the measurement object.

  Here, it is preferable that the conducting wire portion is formed in a state that is not easily broken by the conductive paint. Moreover, the said detection area | region can be set as the structure provided in the multiple places of the said measuring object. For example, the measurement object is a prestressed concrete structure, and the detection region can be provided so as to be applicable to a calculation calculation of a dynamic response that acts when an arrangement pattern of PC steel materials and a train pass.

  The invention of a crack detection method is a crack detection method for detecting a crack generated in a measurement object, comprising a step of providing a detection unit that is easily broken by a conductive paint, and a conductive paint continuously to the detection unit. A step of providing a conductive wire portion that is not easily broken, a step of connecting an electrical data collection unit to an end of the conductive wire portion to form an electric circuit, a step of collecting detection information by the detection unit in the data collection unit, And a step of determining the presence or absence of cracks from the detection information stored in the data collection unit.

  In the crack detection system of the present invention configured as described above, a plurality of rows of detection portions formed in a state that is easily broken by the conductive paint are provided in a detection region where it is desired to detect cracks in the measurement target.

  For this reason, even if a detection error occurs in one row of detection units, the detection accuracy of the detection units formed of the conductive paint can be improved by combining the detection results of a plurality of rows of detection units.

  Further, when the conductive wire portion is formed in a state that is not easily broken by the conductive paint in addition to the detection portion, it can be easily connected to the detection portion similarly formed by the conductive paint, and the appearance can be made homogeneous.

  Detection areas where such detection units are provided can be provided at a plurality of locations to be measured. For example, if the object to be measured is a prestressed concrete structure and a detection region is provided so that it can be applied to the calculation calculation of the PC steel arrangement pattern and the dynamic response acting when passing through the train, The location can be estimated.

  Further, in the crack detection method of the present invention, a conductive wire part is provided by a conductive paint continuously to a detection part provided by the conductive paint, and the detection information detected by the detection part is stored in the data collection part, and based on the detection information. Let the crack be judged. For this reason, it becomes possible to determine a crack more objectively than an inspection such as visual inspection.

It is explanatory drawing which showed schematic structure of the crack detection system of this Embodiment. It is a perspective view explaining the structure of the PC girder used as a measuring object. It is sectional drawing explaining the structure of a conducting wire part and a detection part. It is explanatory drawing which illustrates the wiring pattern of a detection part and a conducting wire part. It is explanatory drawing which illustrated the detection information when the crack has not generate | occur | produced. It is explanatory drawing which illustrated the detection information when the crack has generate | occur | produced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view for explaining a schematic configuration of a crack detection system according to the present embodiment, and FIG. 2 is a perspective view for explaining a configuration of a PC girder 1 to be measured by the crack detection system.

  First, the configuration of the PC girder 1 will be described with reference to FIG. A prestressed force is introduced into the PC girder 1 which is a prestressed concrete structure by a plurality of PC steel materials 11A, 11B, 11C, and 11D.

  Although the grout is filled around the PC steel material 11A-11D, a part of the PC steel material 11A-11D may break due to insufficient grout filling or deterioration during construction.

  Here, even if a part of the PC steel material 11A-11D is broken, the prestressed force remains at a place away from the breakage position, and no problem occurs immediately. However, since the proof stress of the PC girder 1 decreases around the fractured part, it is desirable to take measures such as reinforcement at an early stage.

  On the other hand, when the PC girder 1 is provided on the railway bridge, if the train running load due to the passing of the train dynamically acts, the PC girder 1 will bend and a crack C such as a bending crack will occur instantaneously. There are things to do. If the degree of deterioration of the PC girder 1 can be determined at the stage where the cracks are temporarily generated, it becomes possible to take measures for reinforcement at an early stage, and it is possible to extend the life and suppress the expansion of the deterioration. It becomes like this.

  Then, depending on where the crack C is generated in the PC girder 1, it may be understood which PC steel material 11A-11D is broken or in which position a defective state exists.

  In particular, in railway bridges, the train running load can be specified as a dynamic load. Therefore, the position where the proof stress is reduced can be estimated from the position of the crack C generated by the influence, and the PC placed at that position can be estimated. It becomes possible to specify that the steel materials 11A-11D are broken.

  Therefore, in the crack detection system of the present embodiment, as shown in FIG. 1, the detection units 3,. Here, since the bending crack of the PC girder 1 first occurs on the girder lower surface 12, the detection unit 3 is provided on the girder lower surface 12.

  From the end of the detection unit 3, the conducting wire unit 4 is provided toward the beam end 14 of the PC girder 1 installed on the pier 2. Usually, the pier 2 is in a state where the manager can easily access it, for example, there are stairs and scaffolding.

  Therefore, the data collection unit 5 is attached to the upper part of the side surface 21 of the bridge pier 2 and connected to the terminals 4 a and 4 b of the conducting wire unit 4 by lead wires 51 and 51. The data collection unit 5 stores detection information of the detection unit 3 described later.

  The detection information stored in the data collection unit 5 is transmitted, for example, periodically by radio to the analysis unit 6 installed in the management building or the like. The analysis unit 6 is configured by a personal computer or the like, and can detect detection information, a crack determination result, and the like by using a connected monitor 61.

  FIG. 3 is a cross-sectional view illustrating the configuration of the conductive wire portion 4 and the detection portion 3. The conducting wire portion 4 is mainly configured by a tape main body portion 42 having a stretchability formed in a belt shape and a conductive paint layer 43 having a stretchability formed on the surface of the tape main body portion 42.

  The tape main body 42 is formed of a material having high stretchability. For example, a polyolefin resin material can be used as the tape main body 42. Specifically, fine line tape with high heat resistance (product number 2800, manufactured by 3M Corporation) can be used. Further, the tape main body 42 can be formed of a stretchable material such as nylon.

  The tape main body portion 42 formed of such a synthetic resin material having excellent stretchability can follow the deformation without breaking even if the expansion and contraction is repeated. In addition, the compatibility with the conductive coating layer 43 and the undercoat material 41 described later is good, and it is possible to increase adhesion and make it difficult to peel off.

  On the other hand, the conductive paint layer 43 is blended with excellent stretchability. In order to detect cracks with the conductive paint, it is necessary to reduce the tensile resistance to facilitate breakage. For example, the conductive paint used at the detection location is blended with polyester having poor stretchability.

  In contrast, the conductive paint layer 43 is blended with a resin having excellent stretchability. For example, a silver powder serving as a filler, a highly stretchable urethane resin, and an organic solvent are blended. As the organic solvent, a diluent such as thinner is used.

  The conductive paint layer 43 can be blended, for example, with a silver powder mixing ratio of 55-65 wt%, a urethane resin mixing ratio of 5-15 wt%, and an organic solvent mixing ratio of 25-35 wt%.

  Furthermore, the surface of the conductive paint layer 43 can be covered with a coating layer 44 as necessary. By covering with a coating layer 44 such as an acrylic resin, durability such as ultraviolet resistance and waterproofing can be improved.

  Further, by covering the surface of the conductive paint layer 43 with the coating layer 44, it is possible to make it difficult for the conductive paint layer 43 to be peeled off from the tape main body 42 even when the conductive wire portion 4 repeatedly expands and contracts.

  An epoxy resin or the like can be used for the undercoat material 41 interposed between the tape main body 42 and the underside 12 of the beam. By interposing the undercoat material 41 as a primer, unevenness with a measurement object having irregularities such as a concrete surface (girder lower surface 12) of the PC girder 1 can be adjusted, and leakage to the PC girder 1 side is prevented. be able to.

  In short, the conductor portion 4 is a strip-like conductive material capable of forming an electric circuit composed of a conductive paint. For this reason, if the end portions of the lead wires 51, 51 of the data collecting unit 5 are connected to both ends of the conductive paint layer 43 of the conducting wire portion 4, the energized state can be achieved.

  On the other hand, the detection unit 3 that detects cracks is formed in a state that is easily broken by the conductive paint. That is, the detection unit 3 is mainly configured by a tape portion 32 that is easily broken and formed in a strip shape, and a detection coating layer 33 that is easily broken and formed on the surface of the tape portion 32.

  A non-woven tape, a polyester masking tape, or the like can be used for the tape portion 32. When the tape portion 32 is made of a material that is difficult to break, the tape portion 32 is cut when a desired force is applied, for example, by making slits or the like.

  The detection paint layer 33 is blended with, for example, a silver powder serving as a filler, a polyester resin having poor stretchability, and an organic solvent. As the organic solvent, a diluent such as thinner is used.

  About the undercoat material 31 and the coating layer 34 of the detection part 3, the material similar to the conducting wire part 4 can be used. For example, an epoxy resin can be used for the undercoat material 31 and an acrylic resin can be used for the coating layer 34.

  FIG. 4 is an explanatory diagram illustrating the wiring patterns of the detection unit 3 and the conductive wire unit 4 provided on the lower surface 12 of the girder. Here, a region where cracks on the underside of the girder 12 are to be detected is divided into a plurality of detection regions PA, PB, PC, PD, and PE from the end of the girder 14 toward the span center 13. That is, it is possible to estimate by analysis which PC steel material 11A-11D is broken at which position depending on where the crack is generated in the detection area PA-PE.

  In the detection area PA, three rows of detection units 3A1, 3A2, and 3A3 are provided in parallel. The detection units 3A1, 3A2, and 3A3 are wired in a U shape. Terminals 3a and 3b which are ends of the U-shaped detection units 3A1, 3A2 and 3A3 are connected to lead wires 51 and 51 of the data collection unit 5, respectively.

  Although the three rows of detection units 3A1, 3A2, and 3A3 are all arranged to detect cracks occurring in the same detection area PA, the detection accuracy can be improved by using three rows instead of a single row. . Hereinafter, overlapping description will be omitted as appropriate.

  In the detection area PB adjacent to the detection area PA, three rows of detection units 3B1, 3B2, and 3B3 are provided in parallel. The detection units 3B1, 3B2, and 3B3 are wired in a U-shape, and the conductive wire portions 4B1, 4B2, and 4B3 are connected to both ends thereof. Terminals 4a and 4b serving as end portions of the conductive wire portions 4B1, 4B2 and 4B3 are connected to lead wires 51 and 51 of the data collecting portion 5, respectively.

  Similarly, detection parts 3C1, 3C2, and 3C3 are provided in the detection area PC and connected to the conductor parts 4C1, 4C2, and 4C3, and detection parts 3D1, 3D2, and 3D3 are provided in the detection area PD and the conductor part 4D1, 4D2 and 4D3 are connected, and the detection area PE is provided with detection units 3E1, 3E2, and 3E3, which are connected to the conductor portions 4E1, 4E2, and 4E3. By setting it as such a wiring pattern, even if a crack generate | occur | produces in which detection area PA-PE, a crack can be detected now with high detection accuracy.

  Here, as shown in FIG. 3, it is assumed that a crack C <b> 2 has occurred in the laying section of the conductor portion 4 before the crack C <b> 1 to be detected by the detector 3 occurs. Since the conducting wire part 4 arranged over the crack C2 is excellent in stretchability, even if the crack C2 is repeatedly opened and closed or widened, it can continue to be energized without being broken. For example, even if the crack C2 spreads by about 1 mm, the conducting wire portion 4 can maintain an energized state without breaking.

  On the other hand, when the crack C <b> 1 occurs or spreads, the detection unit 3 is broken and the energization is interrupted, and the detection information is stored in the data collection unit 5. That is, since the tape part 32 and the detection paint layer 33 of the detection part 3 are poor in stretchability, they cannot resist the tensile force acting due to the generation or expansion of the crack C1 and cause breakage. For example, when a crack C1 of about 0.3 mm occurs, the detection unit 3 is broken. However, it is said that there is a detection error of about 25%.

Next, the crack detection method using the crack detection system of this Embodiment and those effect | actions are demonstrated.
As shown in FIG. 2, in order to detect the crack C generated in the PC girder 1 to be measured, the detection unit 3 and the conductive wire unit 4 are arranged on the girder lower surface 12. In this PC girder 1, four stages of PC steel materials 11A-11D are arranged facing the bridge axis direction at intervals in the vertical direction.

  Therefore, as shown in FIG. 4, from the end portion 14 of the underside of the girder 12, so that it can be estimated by reproduction calculation which of the four stages of the PC steel material 11 </ b> A- 11 </ b> D broke and at which position it broke. The span center 13 is divided into five detection areas PA-PE so that the occurrence of cracks in each detection area PA-PE can be detected. In addition, dividing into five detection areas PA-PE is an example, and it may be smaller or larger than that.

  In order to lay the conductor portion 4, first, as shown in FIG. 3, an epoxy resin is applied as an undercoat material 41 to the underside 12 of the PC girder 1. Similarly, an epoxy resin is applied as a primer 31 to the surface of the location where the detection unit 3 is provided.

  And the tape part 32 about 5 mm wide is affixed on the undercoat 31 in the location used as the detection part 3. In addition, a tape main body 42 having a width of about 5 mm is pasted on the undercoat material 41 at a location to be the conductor portion 4.

  Subsequently, in order to form the conductive paint layer 43, a conductive paint in which silver powder, a urethane resin, and an organic solvent are blended is sprayed on the surface of the tape main body portion 42 with a small-diameter spray gun. In addition, a conductive paint containing silver powder, a polyester resin, and an organic solvent is sprayed on the surface of the tape portion 32 to form the detection paint layer 33. The thickness (film thickness) of the detection paint layer 33 by spraying is about 0.05 mm. The film thickness of the conductive paint layer 43 can be made larger than that of the detection paint layer 33.

  Here, although the conductive paint layer 43 and the detection paint layer 33 are formed by spraying the same quality conductive paint, although different in composition, continuity can be easily ensured. Although the connection location between the conductive paint layer 43 and the detection paint layer 33 may be difficult to approach after the installation work, the management burden can be reduced by making the connection highly integrated.

  Furthermore, coating layers 44 and 34 are formed on the surfaces of the conductive paint layer 43 and the detection paint layer 33 by spraying acrylic resin. By providing the coating layers 44 and 34, durability can be improved.

  And the lead wire 51 of the data collection part 5 is connected to the terminals 4a and 4b of the conducting wire part 4 (terminals 3a and 3b for the detection parts 3A1 to 3A3) as shown in FIG.

  Since the connection between the lead wire 51 and the conductive paint layer 43 (or the detection paint layer 33) is made near the pier 2 that is easy for the administrator to access, if trouble such as corrosion or disconnection of the lead wire 51 occurs, Can be found immediately.

  And the data collection part 5 is attached to the side surface 21 of the pier 2 in which a scaffold exists. In this way, using the electrical circuit formed by the conductive wire portion 4, the detection portion 3, and the data collection portion 5, measurement of crack detection information by the data collection portion 5 is performed.

  The data of the detection information stored in the data collection unit 5 is transmitted to the analysis unit 6 installed in the management building on a regular basis, for example, once a day by radio. Or, when the administrator comes near the data collection unit 5 with a data acquisition terminal (tablet terminal, smart phone, etc.), it is detected wirelessly (such as ZigBee (registered trademark) or mobile phone data communication function) It is also possible to obtain information data.

  5A and 5B show an example in which the voltage of the electric circuit serving as detection information is displayed on the monitor 61 of the analysis unit 6 together with the deflection generated in the PC digit 1. In FIG. 5A, even if a deflection occurs in the PC digit 1, the voltage value shows a constant value at all times, and it can be seen that it is in an energized state. That is, in any of the detection units 3A1-3E3, a state where no crack is detected is shown.

  On the other hand, in FIG. 5B, when a large deflection occurs in the PC girder 1, the voltage value is reduced (not energized), and it can be seen that the breakage occurred. That is, it is shown that a crack is detected by any one of the detection units 3A1-3E3. Which detection unit 3A1-3E3 has detected the crack can be easily confirmed from the identifier given to the detection information.

  And if the location which the crack generate | occur | produced can be specified, possibility that which PC steel materials 11A-11D will fracture | rupture at which position will be high by performing the analysis (reproduction calculation) which made the train which passed at that time dynamic load (Number of breaks and break position) can be estimated.

  The crack detection system of the present embodiment configured as described above is a detection in which the detection unit 3 formed in a state that is easily broken by the conductive paint wants to detect cracks on the lower surface 12 of the PC girder 1 to be measured. A plurality of columns (three columns in the above example) are provided in each area PA-PE.

  For this reason, even if a detection error occurs in one row of detection units (for example, 3A1), the detection results of the detection unit 3 formed of the conductive paint can be obtained by combining the detection results of a plurality of rows of detection units (for example, 3A2, 3A3). Detection accuracy can be improved.

As an example, the error rate at which a crack of 0.3 mm or more cannot be detected by the detection unit 3 formed of conductive paint is about 25%. On the other hand, the detection success rate is increased to 98% (= 1− (0.25) ³ × 100 = 98.4%) by providing three detection units 3A1, 3A2 and 3A3 in parallel for one detection area PA. Can be improved.

  Furthermore, since the conductive wire layer 4 has a structure in which a conductive paint layer 43 having elasticity is formed on the surface of the tape main body part 42 having elasticity, cracks may occur at places where no detection is planned, Even if C2 is opened and closed, it is not broken and the current-carrying state of the electric circuit can be maintained.

  Moreover, the detection part 3 comprised by apply | coating a conductive paint and the conductive paint layer 43 of the conducting wire part 4 are familiar, and can be easily made to continue to the detection paint layer 33 of the detection part 3.

  Furthermore, since the conductive paint layer 43 and the detection paint layer 33 are conductive paints using the same silver powder as a filler, the appearance is the same, and the appearance is impaired even if it is exposed on the underside 12 of the PC girder 1. Can be suppressed.

  Then, by providing detection areas PA-PE in accordance with the arrangement pattern of the PC steel material 11A-11D at a plurality of locations of the PC girder 1 which is a prestressed concrete structure, a defective portion or a fractured portion of the PC steel material 11A-11D is estimated. become able to.

  If it is possible to quickly identify the location of cracks in this way, it is possible to take reinforcement measures rationally and economically, such as by partially reinforcing only the locations of cracks with steel plate reinforcement. Become.

  Moreover, the conducting wire part 4 is provided by the conductive paint continuously to the detection part 3 provided by the conductive paint, and the detection information detected by the detection part 3 is stored in the data collecting part 5, and determination of cracks is performed based on the detection information. If it is a method to perform, it can judge the presence or absence of a crack objectively compared with the case where an administrator test | inspects by visual observation or a hammering sound.

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are not limited to this embodiment. Included in the invention.

  For example, in the above-described embodiment, the case where three rows of U-shaped detection units 3 are arranged in each detection area PA-PE has been described. However, the present invention is not limited to this. The part 3 can also be provided.

  Moreover, in the said embodiment, although the conducting wire part 4 formed in the state which is hard to fracture | rupture with a conductive paint was demonstrated, it is not limited to this, An electric wire can also be used as a conducting wire part.

1 PC girder (prestressed concrete structure)
11A-11D PC steel 12 Girder bottom surface (measurement target)
3 Detection part 4 Conductor part 4a, 4b Terminal (end part)
5 Data collection unit 6 Analysis unit C, C1 Cracked PA-PE detection area

Claims (5)

A crack detection system for detecting cracks generated in a measurement object,
A detection part formed in a state easily broken by a conductive paint,
A conductor portion connected to the detector;
A data collection unit connected to the conductor part,
The detection unit is provided with a plurality of rows in a detection region where it is desired to detect a crack of the measurement target.   The crack detection system according to claim 1, wherein the conductor portion is formed in a state that is not easily broken by a conductive paint.   The crack detection system according to claim 1, wherein the detection area is provided at a plurality of locations of the measurement target.   The said measurement object is a prestressed concrete structure, The said detection area is provided so that it can apply to the reproduction calculation of the dynamic response which acts at the time of the arrangement pattern of PC steel materials and a train passage, The 1 thru | or 4. The crack detection system according to any one of 3 above. A crack detection method for detecting a crack generated in a measurement object,
A step of providing a detection part in a state that is easily broken by a conductive paint;
A step of providing a conductive wire portion that is not easily broken by the conductive paint continuously to the detection portion;
Connecting a data collection unit to an end of the conducting wire unit to form an electrical circuit;
Collecting the detection information by the detection unit in the data collection unit;
And a step of determining the presence or absence of a crack from the detection information stored in the data collection unit.