CN112198172A - Bridge inhaul cable steel wire damage detection method and detection device - Google Patents
Bridge inhaul cable steel wire damage detection method and detection device Download PDFInfo
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Abstract
The invention relates to the technical field of bridge detection, in particular to a method and a device for detecting damage of a steel wire of a bridge inhaul cable, wherein the method comprises the following steps: applying pulse ultrahigh frequency alternating current to the exciting coil to excite free electrons in the steel wire of the inhaul cable to form electromagnetic wave guided waves; detecting an excitation pulse signal of the electromagnetic wave guided wave which firstly passes through the detection coil and a reflected pulse signal which passes through the detection coil after being reflected; and acquiring the time for the excitation pulse signal and the reflection pulse signal to pass through the detection coil so as to determine the damage position of the inhaul cable. The invention can solve the problems of time and labor waste and safety risk in the prior art when the ultrasonic guided wave is adopted to detect the stay cable anchoring area.
Description
Technical Field
The invention relates to the technical field of bridge detection, in particular to a method and a device for detecting damage of a steel wire of a bridge inhaul cable.
Background
Since the 80 s of the last century, many newly-built large and medium-sized bridges all adopt stay cable bearing structures. With the increase of the age of a bridge, nondestructive inspection of the broken steel wire inside the inhaul cable is an urgent need of the related industries. Several companies have developed robots capable of performing video detection on the outside of a stay cable and nondestructive flaw detection on broken steel wires inside the stay cable at home and abroad, but such products are only suitable for detecting stay cable bodies without covering the surfaces and cannot detect steel wires in fixed anchors at two ends of the stay cable. According to the analysis of the examples of bridge cable fracture in recent years, the cable fracture often occurs in the anchorage device or a part close to the root of the anchorage device (hereinafter referred to as an "anchorage root region"), because the steel wires in the anchorage root region bear tensile load and simultaneously superpose bending moment load caused by wind swing, the fatigue damage is more easily generated compared with other parts.
A typical bridge inhaul cable end fixing anchorage device structure is shown in a figure 1, and at present, the ultrasonic guided wave detection principle is almost adopted for a practical method for detecting the flaw of a steel wire in a bridge inhaul cable anchorage root area. The operation process is that the rear cover plate of the anchor cup is opened, the steel wire 21 of the inhaul cable 2 to be detected is positioned, the tail end of the inhaul cable is removed from rust, the steel wire is polished to be smooth and flat, the ultrasonic coupling agent is coated, and then the ultrasonic transducer 102 is tightly attached to the tail end of the steel wire. The basic working principle is that an ultrasonic transducer transmits ultrasonic pulses to be transmitted into a steel wire through a coupling agent 103, ultrasonic guided waves are formed and transmitted along the inside of the steel wire, when the guided waves meet internal defects of the steel wire, the guided waves are reflected, and the reflected waves reach the transducer and then are converted into electric pulses, as shown in fig. 2. The flaw detector directly displays the result in the form of oscillogram, or the processor calculates the time difference between the excitation emitting wave and the reflected wave and the amplitude of the reflected wave to obtain the position and size information of the flaw in the steel wire.
Engineering practice proves that the method can detect the fracture defect within 3 meters away from the tail end of the steel wire, but has the inherent problems:
the operator must open the back cover plate 101 of the anchor cup 100 for manual inspection, and for this reason must climb up the pylon or enter under the bridge floor to access the cable anchorage, which is time consuming, labor intensive and presents a safety risk. Because ultrasonic transducer must contact the steel wire tail end and detect a flaw, so the factor that influences data reliability is more: the tail end of the steel wire must be firstly rusted and polished smoothly and brightly, the end plane must be perpendicular to the axis of the steel wire and uniformly coated with a coupling agent, and the like, otherwise, the ultrasonic wave conduction efficiency will be reduced, and the formation of guided waves inside the steel wire may be influenced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method and a device for detecting damage of a steel wire of a bridge stay cable, which can solve the problems that the detection of an anchor area of the stay cable by adopting ultrasonic guided waves in the prior art wastes time and labor and has safety risks.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
on one hand, the invention provides a method for detecting damage of a steel wire of a bridge inhaul cable, which is characterized by comprising the following steps of:
applying pulse ultrahigh frequency alternating current to the exciting coil to excite free electrons in the steel wire of the inhaul cable to form electromagnetic wave guided waves;
detecting an excitation pulse signal of the electromagnetic wave guided wave which firstly passes through the detection coil and a reflected pulse signal which passes through the detection coil after being reflected;
and acquiring the time for the excitation pulse signal and the reflection pulse signal to pass through the detection coil so as to determine the damage position of the inhaul cable.
On the basis of the technical scheme, the step of determining the damage position of the inhaul cable comprises the steps of determining the damage position of the inhaul cable in the length direction, and comprises the following steps:
calculating the distance between a reflection point of the reflected pulse signal and the detection coil according to the time of the excitation pulse signal and the reflected pulse signal passing through the detection coil;
and judging whether the distance between the reflection point and the detection coil is smaller than the distance between the detection coil and the end part of the steel wire, if so, the reflection point is a damaged position, and if not, the reflection point is the end part of the steel wire.
Based on the technical scheme, the method is based on a formula
Calculating the distance L between the reflection points and the detection coil, wherein v0Is the propagation velocity of electromagnetic waves in the steel wire, t1To detect the moment of the excitation pulse signal, t2The moment when the reflected pulse signal is detected.
On the basis of the technical scheme, the step of determining the damage position of the inhaul cable further comprises the step of determining the damage position of the inhaul cable in the circumferential direction, and the method comprises the following steps:
when detecting the electromagnetic wave guide wave passing through the detection coil, simultaneously detecting the time of an excitation pulse signal and a reflection pulse signal passing through the detection coil through each sub-detection Rogowski coil;
when a plurality of adjacent sub-detection Rogowski coils detect a reflected pulse signal at the same time and the distance between the reflection points corresponding to the reflected pulse signal and the detection coil is determined to be smaller than the distance between the detection coil and the end part of the steel wire, the strength of the induction signals of the plurality of sub-detection Rogowski coils is compared, and the sub-detection Rogowski coil with the strongest induction signal strength is determined to be the damage position of the guy cable in the circumferential direction.
On the other hand, the invention provides a detection device of a bridge inhaul cable steel wire damage detection method, which comprises the following steps:
the excitation coil is sleeved on the inhaul cable so as to excite free electrons in the steel wire of the inhaul cable to form electromagnetic wave guided waves;
the detection coil is sleeved on the inhaul cable between the anchorage device and the excitation coil to detect an excitation pulse signal of the electromagnetic wave guided wave passing through the detection coil for the first time and a reflected pulse signal of the electromagnetic wave guided wave passing through the detection coil after being reflected;
and the analysis processing device is connected with the detection coil and is used for recording the time of the excitation pulse signal and the reflection pulse signal of the electromagnetic wave guided wave passing through the detection coil so as to determine the damage position of the steel wire of the inhaul cable.
On the basis of the above technical solution, the excitation coil includes: the coil comprises a mica or ceramic annular framework and an excitation Rogowski coil wound on the annular framework.
On the basis of the technical scheme, the detection coil comprises an annular ferrite magnetic yoke and a detection Rogowski coil wound on the annular ferrite magnetic yoke.
On the basis of the technical scheme, the detection Rogowski coil comprises a plurality of sub detection Rogowski coils, the annular ferrite magnetic yoke comprises ferrite sub magnetic yokes with the same number as the sub detection Rogowski coils, and the sub detection Rogowski coils are respectively sleeved on the ferrite sub magnetic yokes.
On the basis of the technical scheme, an air gap is reserved between the ferrite sub-yokes.
On the basis of the technical scheme, the analysis processing device is a pulse ultrahigh frequency amplification frequency discriminator which is used for receiving the detection signal of the detection coil and calculating the time difference between the excitation pulse signal and the reflection pulse signal so as to determine the steel wire damage position of the inhaul cable.
Compared with the prior art, the invention has the advantages that: when the device for detecting the damage of the steel wire of the bridge inhaul cable is used, the exciting coil is sleeved on the inhaul cable, the detecting coil is sleeved on the inhaul cable between the anchorage device and the exciting coil, pulse ultrahigh frequency alternating current is applied to the exciting coil, and free electrons in the steel wire of the exciting inhaul cable form electromagnetic wave guided waves; detecting an excitation pulse signal of the electromagnetic wave guided wave which firstly passes through the detection coil and a reflected pulse signal which passes through the detection coil after being reflected; and acquiring the time for the excitation pulse signal and the reflection pulse signal to pass through the detection coil so as to determine the damage position of the inhaul cable. The electromagnetic wave guided wave replaces the ultrasonic wave guided wave to propagate in the stay cable steel wire, the steel wire damage of the bridge stay cable anchor root area is detected, the energy is only converted between an electric field and a magnetic field, and the conversion efficiency is much higher than the efficiency of the mutual conversion between the electromagnetic energy and the ultrasonic energy. Therefore, the detection accuracy is greatly improved. An operator does not need to open the rear cover plate of the anchor cup to carry out manual flaw detection, and the guy cable anchoring part can be accessed without climbing up a bridge tower or entering the bridge floor, so that time and labor can be saved, and the safety risk can be reduced. Compare in ultrasonic transducer must contact the steel wire tail end and detect a flaw, needn't get rid of the corrosion to the steel wire tail end, polish level and smooth bright, the end plane needn't be perpendicular with the steel wire axis, and need not to paint couplant, can improve detection efficiency.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic view of a cable end anchor according to the background of the present invention;
FIG. 2 is a basic schematic diagram of the ultrasonic guided wave detection of the defects of the steel wire in the background art of the invention;
FIG. 3 is a schematic structural diagram of a detecting device according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an overall inspection system in an embodiment of the invention;
fig. 5 is a schematic layout diagram of a sub-detection rogowski coil in an embodiment of the present invention.
In the figure: 1. an excitation coil; 11. an annular skeleton; 12. exciting the Rogowski coil; 2. a cable; 21. a steel wire; 3. a detection coil; 31. an annular ferrite yoke; 311. a ferrite sub-yoke; 32. detecting the Rogowski coil; 321. detecting the Rogowski coil; 100. an anchor cup; 101. a back cover plate 102, an ultrasonic transducer; 103. a coupling agent.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
As shown in fig. 3 and 4, the invention provides a method for detecting damage to a steel wire of a bridge inhaul cable, which comprises the following steps:
s1: and applying pulse ultrahigh frequency alternating current to the excitation coil 1 to excite free electrons in the steel wire of the inhaul cable 2 to form electromagnetic wave guided waves.
In this embodiment, a Rogowski coil (Rogowski coil), i.e., a ring-shaped solenoid coil, is fitted around the outer side of the stay as an excitation coil. And strong pulse ultrahigh-frequency alternating current is applied to the exciting coil, so that the Rogowski coil generates an ultrahigh-frequency alternating magnetic field surrounding the inhaul cable steel wire. According to the faraday electromagnetic induction equation in Maxwell's equations:
wherein, l is the perimeter of the closed curved surface where the electric field is located, B is the magnetic flux passing through the closed curved surface,
for the rate of change of the magnetic flux through the curved surface with respect to time, S is the closureThe area of the resultant surface, t, is the time. The ultrahigh frequency alternating magnetic field induces ultrahigh frequency alternating current electromotive force E in each stay wire, so that free electrons in the steel wires move according to the field intensity direction of the ultrahigh frequency alternating current electromotive force. Because the closed loop plane of the magnetic field is orthogonal to the axial direction of the steel wire, the direction of the electromotive force E is superposed with the axial direction of the steel wire, and free electrons are driven to form electromagnetic waveguide waves to be transmitted to the two ends of the steel wire.
S2: and detecting an excitation pulse signal of the electromagnetic wave guided wave which firstly passes through the detection coil 3 and a reflected pulse signal which passes through the detection coil 3 after being reflected.
Between the exciting coil and the cable anchor, the Rogowski coil is sleeved outside the cable to serve as a detection coil. According to the full current equations in the Maxwell system of equations:
wherein: h is the magnetic field strength, l is the perimeter of the closed curve formed by the magnetic field, J is the intensity of the conduction current (i.e., the persistent current in the conductor) passing through the closed curve, D is the intensity of the displacement current (i.e., the non-persistent charge displacement in the conductor or non-conductor) passing through the closed curve, S is the area of the closed curve, and t is the time.
When electromagnetic excitation wave or reflected wave is transmitted in the steel wire (with displacement current)
Existing), an ultrahigh frequency synchronous alternating magnetic field H surrounding the steel wire is generated, and the magnetic field is collected by each ferrite sub-yoke, so that the sub-detection rogowski coil wound thereon generates an ultrahigh frequency induction voltage signal.
S3: and acquiring the time of the excitation pulse signal and the reflected pulse signal of the electromagnetic wave guided wave passing through the detection coil 3, and determining the damage position of the inhaul cable 2 according to the time of the excitation pulse signal and the reflected pulse signal passing through the detection coil 3.
In some optional embodiments, determining the damage position of the cable 2 includes determining the damage position of the cable 2 in the length direction, and includes:
s31: and calculating the distance between the reflection point of the reflected pulse signal and the detection coil 3 according to the time of the excitation pulse signal and the reflected pulse signal passing through the detection coil 3.
Preferably according to a formula
Calculating the distance L between the reflection points and the detection coil 3, wherein v0Is the propagation velocity of electromagnetic waves in the steel wire, t1To detect the moment of the excitation pulse signal, t2The moment when the reflected pulse signal is detected.
In this embodiment, if all the steel wires have no fracture defects, the reflected pulse signals received by the rogowski coil segments are all formed by the reflection of the tail end face of the steel wire, and the reflection distance is equal to the remaining length of the steel wire. If the measured reflection distance of a certain steel wire is less than the residual length of the steel wire, the steel wire fracture defect can be judged to exist.
S32: and judging whether the distance between the reflection point and the detection coil 3 is smaller than the distance between the detection coil 3 and the end part of the steel wire, if so, the reflection point is a damaged position, and if not, the reflection point is the end part of the steel wire.
In some optional embodiments, determining the damage position of the cable 2 further includes determining the damage position of the cable 2 in the circumferential direction, including:
when detecting the electromagnetic wave passing through the detection coil 3, the time when the excitation pulse signal and the reflection pulse signal pass through the detection coil 3 is detected simultaneously by the respective sub-detection rogowski coils 321.
When the adjacent sub-detection Rogowski coils 321 detect the reflected pulse signals at the same time and the distance between the reflection points corresponding to the reflected pulse signals and the detection coil 3 is determined to be smaller than the distance from the detection coil 3 to the end of the steel wire, the strength of the induction signals of the sub-detection Rogowski coils 321 is compared, and the sub-detection Rogowski coil 321 with the strongest induction signal strength is determined to be the damage position of the inhaul cable 2 in the circumferential direction.
In the embodiment, a segmented Rogowski coil is sleeved outside the inhaul cable to serve as the detection coil. Each Rogowski coil segment, namely the sub-detection Rogowski coil, takes a ferrite sub-magnetic yoke made of ferrite material as a framework to form a receiving unit, and all the receiving units are spliced together to form an annular receiving body.
According to the full current equation in the Maxwell equation set, under the condition that the size, the number of turns and the ferrite sub-magnetic yoke conductivity of the sectional type annular solenoid coil, namely the sub-detection Rogowski coil are known, the induced magnetic field intensity H can be calculated according to the effective value of the induced voltage, and then the intensity of the detected electromagnetic wave guided wave displacement current D is calculated.
If a certain steel wire has electromagnetic wave guided waves to pass through, because the magnetic induction field intensity follows the inverse square law of distance in space, only the Rogowski coil section closest to the steel wire generates the strongest induction signal. This makes it possible to provide the annular receiving body with a circumferential positioning capability.
On the other hand, the invention also provides a device for detecting the damage of the steel wire of the bridge inhaul cable, which particularly comprises: the excitation coil 1 is sleeved on the inhaul cable 2 and used for exciting free electrons in a steel wire of the inhaul cable 2 to form electromagnetic wave guided waves; the detection device also comprises a detection coil 3 which is sleeved on the inhaul cable 2 between the anchorage device and the excitation coil 1 so as to detect an excitation pulse signal of the electromagnetic wave guided wave which firstly passes through the detection coil 3 and a reflected pulse signal which passes through the detection coil 3 after being reflected; the device also comprises an analysis processing device which is connected with the detection coil 3 and used for recording the time of the excitation pulse signal and the reflection pulse signal of the electromagnetic wave guided wave passing through the detection coil 3 so as to determine the steel wire damage position of the inhaul cable 2.
When the bridge inhaul cable steel wire damage detection device is used, an excitation coil 1 is sleeved on an inhaul cable 2, a detection coil 3 is sleeved on the inhaul cable 2 between an anchorage device and the excitation coil 1, pulse ultrahigh frequency alternating current is applied to the excitation coil 1, and free electrons in a steel wire of the excitation inhaul cable 2 form electromagnetic wave guided waves; detecting an excitation pulse signal of the electromagnetic wave guided wave which firstly passes through the detection coil 3 and a reflected pulse signal which passes through the detection coil 3 after being reflected; and acquiring the time for the excitation pulse signal and the reflection pulse signal to pass through the detection coil 3 so as to determine the damage position of the inhaul cable 2. The electromagnetic wave guided wave replaces the ultrasonic wave guided wave to propagate in the stay cable steel wire, the steel wire damage of the bridge stay cable anchor root area is detected, the energy is only converted between an electric field and a magnetic field, and the conversion efficiency is much higher than the efficiency of the mutual conversion between the electromagnetic energy and the ultrasonic energy. Therefore, the detection accuracy is greatly improved. An operator does not need to open the rear cover plate of the anchor cup to carry out manual flaw detection, and the guy cable anchoring part can be accessed without climbing up a bridge tower or entering the bridge floor, so that time and labor can be saved, and the safety risk can be reduced. Compare in ultrasonic transducer must contact the steel wire tail end and detect a flaw, needn't get rid of the corrosion to the steel wire tail end, polish level and smooth bright, the end plane needn't be perpendicular with the steel wire axis, and need not to paint couplant, can improve detection efficiency.
In this embodiment, when the device detects a flaw of a single anchor root area, theoretically, only one pulse excitation is needed to complete the detection of all steel wires on the outer layer of the circumference of the stay cable. If the data reliability is to be improved, only pulse excitation is needed to be repeatedly carried out for more than ten times to form data redundancy superposition. Therefore, the detection time is short, the power consumption of the whole instrument is low, and the capacity and the weight of the battery can be greatly reduced.
In some alternative embodiments, the excitation coil 1 comprises: a mica or ceramic ring bobbin 11, and an excitation rogowski coil 12 wound around the ring bobbin 11.
In this embodiment, the rogowski coil wound on the mica or ceramic framework is sleeved outside the inhaul cable to serve as an excitation coil, and strong pulse ultrahigh frequency alternating current is applied to induce electromagnetic wave guided waves in the steel wire, so that non-contact excitation is realized, the steel wires on the outer layer of the circumference of the inhaul cable are excited simultaneously, and the detection efficiency is greatly improved. Mica or ceramic backbones have very high dielectric constants with little dielectric loss at ultra-high frequencies.
In some alternative embodiments, the detection coil 3 includes an annular ferrite yoke 31, and a detection rogowski coil 32 wound on the annular ferrite yoke 31.
In some optional embodiments, the detecting rogowski coil 32 includes a plurality of sub-detecting rogowski coils 321, the annular ferrite yoke 31 includes ferrite sub-yokes 311 having the same number as the sub-detecting rogowski coils 321, and the sub-detecting rogowski coils 321 are respectively sleeved on the ferrite sub-yokes 311.
In some alternative embodiments, an air gap is left between the ferrite sub-yokes 311.
In the present embodiment, the segmented rogowski coil is wound on the ferrite sub-yoke 311 as the sub-detection rogowski coil 321 and spliced to form the annular receiver, which not only improves the detection sensitivity, but also enables the annular receiver to have the positioning capability in the circumferential direction. The positioning accuracy depends on the number of receiving units.
As shown in fig. 5, in the present embodiment, the number of the sub-detection rogowski coils 321 is 18, and the coverage angle of each sub-detection rogowski coil is 20 °. An air gap is formed between two adjacent sub-detection Rogowski coils, and the magnetic resistance of the air gap is much larger than that of ferrite, so that the signals of the two adjacent sub-detection Rogowski coils are relatively independent, and the crosstalk is small. In the figure, the distance between the broken steel wire and the Rogowski coil detected by No. 1 and No. 18 is shortest, and the distance between the broken steel wire and the Rogowski coil detected by No. 3 and No. 17 is increased by more than one time. According to the inverse square ratio of the signal field intensity to the distance, the distance is doubled, the field intensity is reduced to 1/4, so the signal intensity received by the Rogowski coil No. 3 and No. 17 is greatly reduced compared with the Rogowski coil No. 1 and No. 18. Therefore, the broken steel wire can be proved to be positioned in the circumferential range covered by the No. 1 and No. 18 Rogowski coil, namely, the broken steel wire has the fault positioning capability in the circumferential direction. The resolution of this positioning is related to the number of sub-detection rogowski coils: the more the number of the sub-detection Rogowski coils is, the higher the positioning resolution is, but the more complex the structure is and the higher the cost is.
In some optional embodiments, the analysis processing device is a pulsed ultrahigh frequency amplification discriminator, and is configured to receive the detection signal of the detection coil 3, and calculate a time difference between the excitation pulse signal and the reflection pulse signal to determine the steel wire damage position of the cable 2.
In addition, in the present embodiment, each sub-detection rogowski coil of the detection coil 3 corresponds to a pulse ultrahigh frequency amplification discriminator, processes the received signal, measures the amplitude of the reflected pulse signal, and calculates the time difference between the excitation pulse and the reflected pulse.
In this embodiment, the apparatus further includes a pulse ultrahigh frequency unit, which generates a pulse ultrahigh frequency large current, and generates an electromagnetic wave guided wave by inducing the cable steel wire through the exciting coil. Because the excitation moment has large energy density, the excitation moment is also provided with an energy storage unit for support.
The system also comprises a switch, which is used for polling the n pulse ultrahigh frequency amplification frequency discriminators, acquiring data and providing the data to the master control unit, so as to realize circumferential scanning of the steel cable.
And the device also comprises an excitation control and data processing unit. It is used for automatically controlling the exciting and receiving sequence and adjusting the time of the detection window; receiving the data of each receiving unit, integrating, sequencing and judging to find out the breakage of the steel cable in time; and communicating with an upper computer.
In summary, machine detection is used instead of manual detection. The detection robot is adopted to travel to the positions, close to the anchorage devices, of the two ends of the stay cable along the stay cable, non-contact detection is carried out on the steel wire in the anchor root area, the safety risk of personnel is eliminated, the detection efficiency is improved, and the detection robot is suitable for carrying out large-range general investigation on the damage defects of the steel wire in the anchor root area of the stay cable; the detection system has the capability of simultaneously detecting all steel wires on the outermost layer of the inhaul cable (when the inhaul cable is stretched and bent, the outer layer steel wire is stressed maximally), so that the surface detection full coverage of the steel cable is realized; the detection system has double positioning capability of defects in the length direction and the circumferential direction (longitudinal direction) of the stay cable; has higher detection sensitivity and data reliability.
In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
It is noted that, in the present application, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A bridge inhaul cable steel wire damage detection method is characterized by comprising the following steps:
applying pulse ultrahigh frequency alternating current to the excitation coil (1) to excite free electrons in the steel wire of the inhaul cable (2) to form electromagnetic wave guided waves;
detecting an excitation pulse signal of the electromagnetic wave guided wave which firstly passes through the detection coil (3) and a reflected pulse signal which passes through the detection coil (3) after being reflected;
and acquiring the time for the excitation pulse signal and the reflection pulse signal to pass through the detection coil (3) so as to determine the damage position of the inhaul cable (2).
2. The method for detecting the damage to the steel wire of the bridge guy cable according to claim 1, wherein the step of determining the damage position of the guy cable (2) comprises the steps of:
calculating the distance between the reflection point of the reflected pulse signal and the detection coil (3) according to the time of the excitation pulse signal and the reflected pulse signal passing through the detection coil (3);
and judging whether the distance between the reflection point and the detection coil (3) is smaller than the distance between the detection coil (3) and the end part of the steel wire, if so, the reflection point is a damaged position, and if not, the reflection point is the end part of the steel wire.
3. The method for detecting the damage of the steel wire of the bridge guy cable according to the claim 2, which is characterized in that the method is based on the formula
Calculating the distance L between the reflection points and the detection coil (3), wherein v0Is the propagation velocity of electromagnetic waves in the steel wire, t1To detect the moment of the excitation pulse signal, t2The moment when the reflected pulse signal is detected.
4. The method for detecting the damage to the steel wire of the bridge guy cable according to claim 1, wherein the step of determining the damage position of the guy cable (2) further comprises the step of determining the damage position of the guy cable (2) in the circumferential direction, and comprises the following steps:
when detecting the electromagnetic wave passing through the detection coil (3), simultaneously detecting the time of an excitation pulse signal and a reflection pulse signal passing through the detection coil (3) through each sub-detection Rogowski coil;
when a plurality of adjacent sub-detection Rogowski coils detect the reflected pulse signals at the same time and the distance between the reflection points corresponding to the reflected pulse signals and the detection coil (3) is determined to be smaller than the distance between the detection coil (3) and the end part of the steel wire, the strength of the induction signals of the sub-detection Rogowski coils is compared, and the sub-detection Rogowski coil with the strongest induction signal strength is determined to be the circumferential damage position of the inhaul cable (2).
5. A detection device for implementing the bridge inhaul cable steel wire damage detection method according to claim 1, characterized by comprising:
the excitation coil (1) is sleeved on the inhaul cable (2) to excite free electrons in a steel wire of the inhaul cable (2) to form electromagnetic wave guided waves;
the detection coil (3) is sleeved on the inhaul cable (2) between the anchorage device and the excitation coil (1) to detect an excitation pulse signal of the electromagnetic wave guided wave passing through the detection coil (3) for the first time and a reflected pulse signal of the electromagnetic wave guided wave passing through the detection coil (3) after being reflected;
and the analysis processing device is connected with the detection coil (3) and is used for recording the time of the excitation pulse signal and the reflection pulse signal of the electromagnetic wave guided wave passing through the detection coil (3) so as to determine the steel wire damage position of the inhaul cable (2).
6. A bridge stay wire damage detection device according to claim 5, wherein the exciting coil (1) comprises: the coil comprises a mica or ceramic annular framework (11) and an excitation Rogowski coil (12) wound on the annular framework (11).
7. A device for detecting damage to a steel wire of a bridge cable according to claim 5, wherein the detection coil (3) comprises an annular ferrite yoke (31), and a Rogowski detection coil (32) wound on the annular ferrite yoke (31).
8. The bridge inhaul cable steel wire damage detection device according to claim 7, wherein the detecting Rogowski coil (32) comprises a plurality of sub detecting Rogowski coils (321), the annular ferrite magnetic yoke (31) comprises ferrite sub magnetic yokes (311) with the same number as the sub detecting Rogowski coils (321), and the sub detecting Rogowski coils (321) are respectively sleeved on the ferrite sub magnetic yokes (311).
9. The bridge guy wire damage detection device of claim 8, wherein an air gap is left between the ferrite sub-yokes (311).
10. A bridge guy wire damage detection device according to claim 5, characterized in that the analysis processing device is a pulse UHF amplification frequency discriminator, which is used to receive the detection signal of the detection coil (3) and calculate the time difference between the excitation pulse signal and the reflection pulse signal to determine the steel wire damage position of the guy wire (2).
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| CN115014970A (en) * | 2022-08-10 | 2022-09-06 | 中电建路桥集团有限公司 | Equipment for detecting tension of bridge steel cable |
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