JP5761686B2 - PC cable breakage detection method for PC structures - Google Patents

Description

The present invention, for example, detects the AE sound such as a frictional sound accompanying the breakage of the PC cable, thereby detecting the break point of the PC cable disposed in the post-tension type PC structure. The present invention relates to a PC cable breakage detection method for a PC structure.

Conventionally, in a post-tension type PC structure, the PC cable in the steel sheath is locally corroded due to insufficient grout or bleeding in the disposed steel sheath, and in the worst case, There was a risk that the PC cable would break.
Although PC cable breakage may ultimately be fatal to PC structures, a technology that can detect the PC cable breakage point in the steel sheath in a non-destructive manner in service is currently established. The fact is not.

Here, a possible method for detecting the PC cable breakage point in the steel sheath is to measure the stress and strain of the PC structure, that is, the stress distribution depending on the degree of deformation under the action of an external force such as a load. Measure the state and strength of the PC and detect the breakage point of the PC cable, or irradiate the PC structure with radiation and measure the state of the defect from the change in the intensity of the transmitted radiation. A method for detecting a breakage point of a PC cable, and further, by transmitting ultrasonic waves to a PC structure and using the acoustic properties when the ultrasonic waves are transmitted, exploring differences in internal defects, materials, etc. The method of detecting the breakage point of the PC cable, and the time for the electromagnetic wave to be reflected back at the interface with the substance with different electrical characteristics are measured. That the position of the internal defect to estimate, such a technique that the position and broken portion of PC cable can be considered.

Japanese Patent Laid-Open No. 11-133097

  In some cases, the grout is only partially filled in the steel sheath due to poor construction or the like, and in such a case, a void may be formed in the steel sheath. And when the said space | gap part exists, fear that a PC cable will be easy to fracture | rupture in this space | gap part is pointed out.

However, when the PC cable breaks at the gap, the broken PC cable is fixed again at a place where the grout is sufficiently filled. In this case, the decrease in rigidity of the PC cable break is relatively small, Therefore, it is very difficult to detect the breakage due to the deformation.
Therefore, it can be said that it is not very realistic to measure the stress and strain of the PC structure and thereby detect the breakage point of the PC cable.
In addition, the detection method using radiation described above is not practical for civil engineering structures because the influence of attenuation by the concrete is large and the thickness of the permeable body is limited.

Furthermore, since the detection method using electromagnetic waves is reflected by the steel sheath covering the PC cable, it is difficult to investigate the PC cable in the steel sheath.
Furthermore, in the case of the detection method using an ultrasonic wave or an elastic wave, even if the troubled part of the filling mortar can be grasped, it cannot be specified at which part the PC cable has been broken.

  Thus, in the present situation, it is difficult to detect the breakage point of the PC cable, and there is almost no sign even when the breakage point detection of the PC cable is left unattended. In the worst case, the entire PC structure collapses. Until then, there was a problem that the broken part of the PC cable could not be recognized.

Thus, the present invention was devised to solve the above-described conventional problems, and non-destructive detection of a breakage point of a PC cable in a steel sheath, which has been conventionally recognized as a difficult detection operation. Therefore, it is possible to remarkably improve the level of safety management of PC structures, and the PC cables that swing and fluctuate with the loading of heavy vehicles for the purpose of passing or inspecting normal traffic vehicles. Because it is premised on the detection of frictional noise generated when crushing the weakened grout interface that has been re-fixed, the PC structure has many advantages such as being widely applicable to PC structures under normal service An object of the present invention is to provide a non-destructive detection method for a PC cable breakage point of an object.

The present invention
The PC sheath breakage point in the steel sheath in the existing PC structure using the PC cable arranged in the steel sheath constructed by the post-tension method and filled with grout is used for the existing PC structure. PC cable breakage detection method that can be detected inside,
Search the steel sheath embedment location in the existing PC structure, install a plurality of sound sensors on the surface of the existing PC structure along the searched steel sheath embedment location,
The plurality of sound sensors are re-fixed in the grout filling section after breaking in the steel sheath, which is generated by the weight of a heavy object placed by using the existing PC structure. In the fixing portion, the crushing friction sound of the grout filled in the steel sheath accompanying the fluctuation of the broken PC cable is detected,
By determining the generation position of the friction sound based on the difference in detection time when each sound sensor detected the friction sound and the installation position of the sound sensor, it is possible to detect the PC cable breakage point in the existing structure.
It is characterized by
Or
The PC sheath breakage point in the steel sheath in the existing PC structure using the PC cable arranged in the steel sheath constructed by the post-tension method and filled with grout is used for the existing PC structure. PC cable breakage detection method that can be detected inside,
Search the steel sheath burying location in the existing PC structure, install a plurality of AE sensors on the surface of the existing PC structure along the searched steel sheath burying location,
The plurality of AE sensors are re-fixed in the grout filling portion after breaking in the steel sheath, which is generated by the weight of a heavy object placed by the use of the existing PC structure. In the fixing portion, the crushing friction sound of the grout filled in the steel sheath accompanying the fluctuation of the broken PC cable is detected,
By determining the generation position of the frictional sound based on the difference in detection time detected by each AE sensor and the installation position of the AE sensor, the PC cable breakage point in the existing structure can be detected.
It is characterized by
Or
The PC sheath breakage point in the steel sheath in the existing PC structure using the PC cable arranged in the steel sheath constructed by the post-tension method and filled with grout is used for the existing PC structure. PC cable breakage detection method that can be detected inside,
A steel sheath burying location in the existing PC structure is searched by a design drawing of the existing PC structure or detection by an electromagnetic wave radar, and a plurality of locations are found on the surface of the existing PC structure along the searched steel sheath burying location. Of AE sensor,
The plurality of AE sensors are re-fixed in the grout filling portion after breaking in the steel sheath, which is generated by the weight of a heavy object placed by the use of the existing PC structure. In the fixing portion, the crushing friction sound of the grout filled in the steel sheath accompanying the fluctuation of the broken PC cable is detected,
By determining the generation position of the frictional sound based on the difference in detection time of each AE sensor and the installation position, it is possible to detect the PC cable breakage point in the existing structure.
It is characterized by
Or
In order to detect the PC cable breakage point in the existing structure based on the detection sound from each of the AE sensors, the difference in arrival time of the detection sound detected by each of the AE sensors and the Obtain the position of the frictional sound generated from the PC cable breakage point in the existing structure from the installation position, and detect the PC cable breakage point,
It is characterized by
Or
The existing structure in service is an existing highway, and the heavy object placed on the highway is a traveling traffic vehicle.
It is characterized by
Or
The detection by a plurality of AE sensors is continuously performed, and the status of the existing PC structure accompanying the breakage of the PC cable can be grasped from the information obtained from the friction sound continuously obtained and the change in the detected friction sound.
It will be characterized by that.

According to the PC cable breakage location detection method for a PC structure according to the present invention, a broken PC cable is weak in detecting a breakage location of a PC cable in a steel sheath, which has been conventionally recognized as a difficult operation. By measuring and analyzing the frictional noise generated when crushing the grout interface, it can be easily achieved, and the level of safety management of PC structures can be greatly improved. Since it is premised on the detection of crushing frictional sound accompanying the loading of heavy objects such as, it has an excellent effect that it can be widely applied to PC structures under normal service.

(A), (b) of a figure is schematic structure explanatory drawing (the 1) explaining schematic structure of this invention. It is schematic structure explanatory drawing (the 2) explaining schematic structure of this invention. (A), (b) of a figure is schematic structure explanatory drawing (the 3) explaining schematic structure of this invention. (A), (b) of a figure is schematic structure explanatory drawing (the 4) explaining schematic structure of this invention. It is explanatory drawing (the 1) explaining the structure of the system by this invention. It is explanatory drawing (the 2) explaining the structure of the system by this invention.

DESCRIPTION OF SYMBOLS 1 Expressway 2 Bridge girder 3 PC cable 4 Steel sheath 5 AE sensor 6 Traffic vehicle 7 Switch 8 AE sound 9 Receiving part 10 Distance measuring part 11 Angle meter side part 12 AE sound generating part specific part 13 AE sound generating part 14 AE Sound derivation display unit 15 Transmission unit 16 Control unit 17 Storage unit 18 Display unit 19 Input unit

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  The present invention is constructed by a post-tension method, and the used sheath is a steel sheath 4. Even when the existing PC structure is in use, the breakage point of the PC cable 3 arranged in the existing PC structure is used. The present invention relates to a PC cable breakage detection method that can be detected.

  FIG. 1 is a schematic view of an embodiment in which the present invention is applied to a highway 1 constructed as a PC structure. As can be understood from FIG. 1, the inside of a bridge girder 2 of a highway 1 as an existing PC structure. The steel sheath 4 in which the PC cable 3 is housed and installed in a tensioned state extends in the longitudinal direction and is embedded.

  Here, with regard to the highway 1 which is an existing PC structure, for example, the position of the bridge girder 2 is searched for whether the PC cable 3 shielded by the steel sheath 4 is embedded, and the embedded position is immediately searched from the outside. It is difficult to judge. Therefore, first, it is necessary to search and confirm in which location the PC cable 3 shielded by the steel sheath 4 is embedded in a plurality of locations.

  First, if the location where the PC cable 3 is laid in the existing PC structure cannot be specified, the installation position of the AE sensor 5 for reliable detection cannot be determined accurately. This is because it is difficult to detect the broken portion of the PC cable 3.

  Here, the search and confirmation work is not limited in any way by the search and confirmation work. For example, an original design drawing of the highway 1 that is an existing PC structure is acquired, Confirm the entire installation location of the PC cable 3 embedded in the design drawing, or search by irradiating the surface side of the highway 1 that is an existing PC structure with a search device such as an electromagnetic wave radar. It is conceivable to search, detect and confirm the entire location of the PC cable 3 stored in the PC 4.

  After searching for and confirming a buried portion of the steel sheath 4 in which the PC cable 3 is placed in tension as described above, the existing one is installed along the buried portion of the steel sheath 4 where a broken portion is to be detected. A plurality of AE sensors 5 are installed on the surface of the expressway 1 which is a PC structure (see FIG. 2).

  Here, as shown in FIG. 2, for example, in the bridge girder 2 of the highway 1, for example, in the longitudinal direction from one end side to the other end side, as shown in FIG. If the steel sheath 4 is embedded and installed in a substantially U-shaped curve, a plurality of the sheaths 4 are installed at predetermined intervals in the longitudinal direction of the surface of the bridge beam 2 in accordance with the extending direction. It is supposed to do.

By the way, in the present invention, when it is desired to detect a breakage point of the PC cable 3 for the highway 1, the highway 1 may be used as usual. For example, a heavy traffic vehicle 6 may travel frequently, and the AE sensor 5 functions on the premise of the above-mentioned service.
For the purpose of detection, it may be possible to intentionally run a heavy traffic vehicle or the like to create an in-service state.

  In such a state where the highway 1 is in service, when the PC cable 3 is broken in the steel sheath 4 disposed inside the highway 1, the traffic vehicle that runs on the existing highway 1. A so-called grout crushing frictional sound accompanying breakage of the PC cable 3 is generated by the weight of a heavy object such as 6.

Again, this frictional sound is not a breaking sound due to the breakage of the PC cable 3, but after the breakage, the PC cable 3 is re-fixed in the grout filling portion, but the PC cable 3 broken in the re-fixing portion swings and fluctuates. As a result, the grout is crushed. It is the crushing friction sound at that time.
Then, the plurality of AE sensors 5 installed as described above detect grout crushing friction sound accompanying breakage of the PC cable 3 and detect at which location the PC cable 3 is cut. .

  That is, the plurality of AE sensors 5... Detect grout crushing friction sounds caused by the breakage of the PC cable 3, and the difference in arrival speeds of the respective AE sounds 8 that are detected grout crushing friction sounds, in other words, respectively. From the difference in detection time detected by the AE sensors 5... And the installation positions of the AE sensors 5.

Thereby, the fracture | rupture location of the PC cable 3 of the bridge girder 2 in the highway 1 which is an existing structure is each calculated | required.
In this embodiment, the breakage point of the PC cable 3 is one-dimensionally identified and detected by the frictional sound generation point determined from the plurality of AE sensors 5.

  Next, FIG. 3 shows a second embodiment of the present invention. In this embodiment, a plurality of AE sensors 5... Are gently curved, for example, from the one end side in the longitudinal direction toward the other end side. The steel sheath 4 is arranged with a predetermined interval along the longitudinal direction of the steel sheath 4 embedded and installed as described above. As can be understood from FIG. It is assumed that a plurality of lines 4 are arranged in parallel at intervals toward the upper side and the lower side of 4.

  By installing in this way, a plurality of AE sensors 5... Are installed with a spread in a plane, and the breakage location of the PC cable 3 is determined by the information from each AE sensor 5. An expected crushing frictional sound generation location is determined, and the fracture location of the PC cable 3 is further specified in detail two-dimensionally and can be detected.

FIG. 4 shows a third embodiment of the present invention.
In this third embodiment, as understood from FIG. 3, a plurality of AE sensors 5... Are installed on both sides of a bridge girder 2 having a thickness.
In this way, a plurality of AE sensors 5... Are installed so as to have a so-called three-dimensional depth, and each AE is a crushing friction sound detected by the three-dimensionally installed AE sensors 5. From the sound 8, the location where the crushing frictional sound is generated is determined three-dimensionally based on the difference in detection time when the plurality of AE sensors 5 ... detect the AE sound 8, the installation position of the AE sensor, etc., that is, the PC cable 3 is broken. It is possible to detect in detail whether the cut portion is in which thickness portion.

  Thus, according to the present embodiment, there is a breakage point of the PC cable 3 installed in the steel sheath 4 installed not only in the two-dimensional direction but also in any thickness portion of the bridge girder 2 having a thickness. However, it is possible to specify and detect details in a so-called three-dimensional manner.

5 and 6 use this detection method to continuously detect the state of breakage of the PC cable 3, continuously grasp the status of the PC structure, for example, the expressway 1, and continuously manage its safety. It explains the system configuration of the present invention that can be performed.

Is detected by each AE sensor 5 ..., so-called AE sound 8, and the distance from the AE sensor 5 ... until AE sound 8 occurrence location, in some cases already the angle mentioned above are respectively measured in Stated. In this system, the AE sound 8 can be continuously received and measured from each AE sensor 5..., And the location where the AE sound 8 is generated can be continuously identified, detected, and monitored. It is supposed to be. Moreover, a change in the size of the crushing friction sound can be recognized as a change in the magnitude of the AE sound 8, and these can be detected continuously.

Therefore, based on this information, should the PC structure, for example, the highway 1 be stopped immediately, should it be started immediately, or whether there is still some room for the PC structure to be stopped? It is possible to detect and monitor the state of

In FIG. 5 , each AE sound 8 from the AE sound generation location 13 acquired from the plurality of AE sensors 5... Is received by the receiving unit 9 via the switch 7. The information of the AE sound 8 received by the receiving unit 9 is introduced into the distance measuring unit 10, and the AE sound generation location from the difference in detection time from each AE sensor 5 that detected the AE sound 8 and the installation position of the AE sensor, etc. Each distance up to 13 is measured.

  From the information from the two AE sensors 5 and 5 sandwiching the AE sound generation point 13, the one-dimensional rough AE sound generation point 13 is specified by the AE sound generation point 13 specifying unit 12. It becomes.

  Reference numeral 11 denotes an angle measurement unit. The angle measurement unit 11 is arranged so as to surround the AE sound generation point 13 and the AE sensor 5... The angle of each triangle constituted by a line connecting 5 and the AE sound generation point 13, a line connecting each AE sensor 5, 5 and the AE sound generation point 13, and a line connecting each adjacent AE sensor is measured. .

  Based on the distance measured by the distance measuring unit 10 and the values of the respective angles measured by the angle measuring unit 11, the AE sound generating point specifying unit 12 calculates the AE sound generating point 13 and the movement thereof. Is monitored, and the movement is continuously displayed by the AE sound generation location display unit 14.

FIG. 6 shows a system configuration of the present invention, and this system may be configured by a general computer.

  In addition to the receiving unit 9, the computer includes a transmitting unit 15, a control unit 16 using a CPU, a storage unit 17 configured with a hard disk, a display unit 18 such as a liquid crystal display, and an input unit 19 configured with a keyboard. It is configured to include. Operations such as the distance measuring unit 10, the angle measuring unit 11, and the AE sound generation location specifying unit 12 described above are performed by the control unit 16, and operations such as the AE sound generation location display unit 14 are performed by the display unit 18.

Information such as the identification of the AE sound generation location is stored in the storage unit 17.

Claims (6)

The PC sheath breakage point in the steel sheath in the existing PC structure using the PC cable arranged in the steel sheath constructed by the post-tension method and filled with grout is used for the existing PC structure. PC cable breakage detection method that can be detected inside,
Search the steel sheath embedment location in the existing PC structure, install a plurality of sound sensors on the surface of the existing PC structure along the searched steel sheath embedment location,
The plurality of sound sensors are re-fixed in the grout filling section after breaking in the steel sheath, which is generated by the weight of a heavy object placed by using the existing PC structure. In the fixing portion, the crushing friction sound of the grout filled in the steel sheath accompanying the fluctuation of the broken PC cable is detected,
By determining the generation position of the friction sound based on the difference in detection time when each sound sensor detected the friction sound and the installation position of the sound sensor, it is possible to detect the PC cable breakage point in the existing structure.
PC cable breakage location detection method characterized by this.
The PC sheath breakage point in the steel sheath in the existing PC structure using the PC cable arranged in the steel sheath constructed by the post-tension method and filled with grout is used for the existing PC structure. PC cable breakage detection method that can be detected inside,
Search the steel sheath burying location in the existing PC structure, install a plurality of AE sensors on the surface of the existing PC structure along the searched steel sheath burying location,
The plurality of AE sensors are re-fixed in the grout filling portion after breaking in the steel sheath, which is generated by the weight of a heavy object placed by the use of the existing PC structure. In the fixing portion, the crushing friction sound of the grout filled in the steel sheath accompanying the fluctuation of the broken PC cable is detected,
By determining the generation position of the frictional sound based on the difference in detection time detected by each AE sensor and the installation position of the AE sensor, the PC cable breakage point in the existing structure can be detected.
PC cable breakage location detection method characterized by this.
The PC sheath breakage point in the steel sheath in the existing PC structure using the PC cable arranged in the steel sheath constructed by the post-tension method and filled with grout is used for the existing PC structure. PC cable breakage detection method that can be detected inside,
A steel sheath burying location in the existing PC structure is searched by a design drawing of the existing PC structure or detection by an electromagnetic wave radar, and a plurality of locations are found on the surface of the existing PC structure along the searched steel sheath burying location. Of AE sensor,
The plurality of AE sensors are re-fixed in the grout filling portion after breaking in the steel sheath, which is generated by the weight of a heavy object placed by the use of the existing PC structure. In the fixing portion, the crushing friction sound of the grout filled in the steel sheath accompanying the fluctuation of the broken PC cable is detected,
By determining the generation position of the frictional sound based on the difference in detection time of each AE sensor and the installation position, it is possible to detect the PC cable breakage point in the existing structure.
PC cable breakage location detection method characterized by this.
In order to detect the PC cable breakage point in the existing structure based on the detection sound from each of the AE sensors, the difference in arrival time of the detection sound detected by each of the AE sensors and the Obtain the position of the frictional sound generated from the PC cable breakage point in the existing structure from the installation position, and detect the PC cable breakage point,
The PC cable breakage location detection method according to claim 2 or claim 3, wherein
The existing structure in service is an existing highway, and the heavy object placed on the highway is a traveling traffic vehicle.
The PC cable breakage point detecting method according to claim 1, 2, 3, or 4, wherein:
Detection by the plurality of AE sensors according to claim 2 to claim 4 is continuously performed, and information from the friction sound continuously acquired and a change in the detected friction sound are used to determine whether the existing PC associated with the PC cable breakage. The situation of the structure can be grasped.
A situation detection method for existing PC structures.

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