CN116007797A - Track load monitoring backing plate device, system and calibration method thereof - Google Patents
Track load monitoring backing plate device, system and calibration method thereof Download PDFInfo
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Abstract
The invention provides a track load monitoring backing plate device, a track load monitoring backing plate system and a calibration method thereof. The piezoelectric sensor has the advantages of high sensitivity, high signal-to-noise ratio, reliable operation, simple structure and the like, and can measure high-quality signals. Further, because the sensor fixed plate is installed between upper cover plate and bed plate, and piezoelectric sensor and load transfer post are installed in the sensor mounting groove of sensor fixed plate, fix spacing to piezoelectric sensor through such a mode, can avoid the condition such as the piezoelectric sensor displacement that causes because of the track vibration when the train operates, drop to guarantee the monitoring effect in the train operation process. By the calibration method, the piezoelectric sensor can detect and obtain signals with better quality and higher precision in the target load range.
Description
Technical Field
The invention belongs to the technical field of track monitoring, and particularly relates to a track load monitoring backing plate device, a track load monitoring backing plate system and a track load monitoring backing plate calibration method.
Background
The track structure is widely applied to industries such as industry, transportation and the like, and is used for guaranteeing the safety of track transportation, at present, the track is generally comprehensively maintained once every 3-5 years, and the track structure comprises the steps of integrally adjusting the geometric dimension of the track, replacing and repairing invalid parts and the like so as to comprehensively remove various track diseases and defects, and combining with multiple temporary overhauling, so that the safety and stability of train operation are guaranteed. The current maintenance mode obviously requires a great deal of manpower and time, and needs stop line inspection, and has great influence on train passing.
If the rail can be monitored during normal operation of the train, rail diseases can be found in time and the rail diseases can be maintained in a targeted manner, so that the safety of the rail can be ensured, and a large amount of manpower, material resources and time can be saved. However, at present, when corresponding detection is needed, the sensor is temporarily installed to perform track detection, and a great deal of time is required for installing, wiring, debugging and dismantling the temporary sensor after detection is completed, which is very inconvenient. In addition, different types of sensors have different characteristics, the condition difference of different track scenes is large, and the applicability and the detection precision of the sensor are difficult to ensure for different track conditions.
Disclosure of Invention
The invention aims to solve the problems, and aims to provide a track monitoring device and a track monitoring system which can accurately monitor track loads of various track conditions, wherein the track monitoring device and the track monitoring system adopt the following technical scheme:
the invention provides a track load monitoring backing plate device, which is arranged between a track bed plate and a lower foundation of a ballastless track and is used for monitoring the load under the track bed plate, and is characterized by comprising the following components: a base plate mounted on the lower foundation; the sensor fixing plate is arranged on the base plate and provided with a plurality of upward opening sensor mounting grooves; the upper cover plate is arranged on the sensor fixing plate, and the bottom of the upper cover plate is provided with a cushion layer made of rubber; the piezoelectric sensors are respectively arranged in the sensor mounting grooves; and a plurality of load transfer columns respectively installed in the sensor installation grooves and positioned below the piezoelectric sensors, wherein the piezoelectric sensors comprise flaky piezoelectric crystals, the upper surfaces of the piezoelectric crystals are abutted with the cushion layers at the bottom of the upper cover plate, and the strength of piezoelectric signals obtained through detection of the piezoelectric crystals is in linear relation with the stress level born by the steel rail.
The track load monitoring backing plate device provided by the invention can also have the technical characteristics that the type of the piezoelectric sensor is PACEline 1-CLP/26kN, and the force capacity range is 0-26 kN.
The track load monitoring backing plate device provided by the invention can be further characterized by comprising a cylindrical piezoelectric sensor, and further comprising a metal base, wherein the metal base is provided with an annular groove, the piezoelectric crystal is an annular sheet-shaped quartz plate, the quartz plate is embedded and installed in the annular groove of the metal base, and the upper surface of the quartz plate is abutted against the cushion layer at the bottom of the upper cover plate.
The track load monitoring backing plate device provided by the invention can also have the technical characteristics that the diameter of the piezoelectric sensor is 35mm, the thickness of the piezoelectric sensor is 3.5mm, the diameter of the quartz plate is 18mm, the working environment temperature of the piezoelectric sensor is-20-120 ℃, and the deformation range is 0-3.5 mu m.
The track load monitoring backing plate device provided by the invention can be further characterized in that the sensor fixing plate is in a cuboid shape, the number of the sensor mounting grooves is plural and is distributed at the corner or the edge of the sensor fixing plate, the piezoelectric sensor is connected with cables, the sensor fixing plate is further provided with wiring grooves which are communicated with all the sensor mounting grooves and are communicated with the side edges of the sensor fixing plate, and the cables extend in the wiring grooves and extend from the side edges of the sensor fixing plate.
The track load monitoring backing plate device provided by the invention can also have the technical characteristics that the base plate, the sensor fixing plate and the upper cover plate are all cuboid steel plates, the lengths and the widths of the cuboid steel plates are consistent, and the thickness of the sensor fixing plate is 10-15 mm.
The invention provides a track monitoring system, which is characterized by comprising: at least one track load monitoring backing plate device is arranged below a ballast bed plate of the ballastless track and is used for monitoring the load below the ballast bed plate to obtain a corresponding piezoelectric signal; the signal acquisition device is connected with the track load monitoring backing plate device and is used for acquiring the piezoelectric signals measured by the track load monitoring backing plate device; and the calculation and analysis device is in communication connection with the signal acquisition device and is used for receiving the piezoelectric signals from the signal acquisition device and carrying out calculation and analysis.
The invention provides a calibration method of the track load monitoring backing plate device, which is characterized by comprising the following steps: step S1, attaching a piezoelectric sensor for the track load monitoring pad device on the surface of a resin pad, and connecting a cable of the piezoelectric sensor to a data recorder; step S2, applying a series of loads on the resin backing plate above the piezoelectric sensor through a rectangular actuator, and recording piezoelectric signals measured by the piezoelectric sensor through the data recorder; and step S3, calibrating the pressure value corresponding to the piezoelectric signal by referring to the applied load parameter.
The calibration method of the track load monitoring backing plate device provided by the invention can also have the technical characteristics that in the step S1, the length and the width of the resin backing plate are 100mm, and the thickness is 7mm; in step S2, the rectangular actuator has a section length of 60mm and a section width of 40mm, and a series of the loads have different frequencies and different stress levels.
The actions and effects of the invention
According to the track load monitoring backing plate device and the track load monitoring backing plate system, the track load monitoring backing plate device is arranged below the ballastless track bed plate and comprises a plurality of piezoelectric sensors, so that the load of a track can be monitored through the piezoelectric sensors directly integrated in a track structure. The piezoelectric sensor has the advantages of high sensitivity, high signal-to-noise ratio, reliable operation, simple structure and the like, can detect and obtain high-quality signals, and the piezoelectric signal intensity detected by the piezoelectric sensor is in linear relation rather than exponential relation with the stress level borne by the ballast bed plate, so that the signal detected by the track load monitoring backing plate device can still effectively identify the change of the load even under the condition of high load, and the track load monitoring backing plate device has wide application range and can be suitable for various track conditions. Further, because the sensor fixed plate is installed between upper cover plate and bed plate, and piezoelectric sensor and load transfer post are installed in the sensor mounting groove of sensor fixed plate, fix spacing to piezoelectric sensor through such a mode, can avoid the condition such as the piezoelectric sensor displacement that causes because of the track vibration when the train operates, drop to guarantee the monitoring effect in the train operation process.
According to the calibration method of the track load monitoring pad device, the piezoelectric sensor is attached to the surface of the resin pad, and a series of test loads are applied by the rectangular actuator to calibrate the piezoelectric sensor. By this, the piezoelectric sensor can detect a signal with better quality and higher precision in the target load range, and the piezoelectric crystal can be prevented from being damaged.
Drawings
FIG. 1 is a block diagram of a track load monitoring system in accordance with an embodiment of the present invention;
FIG. 2 is a cross-sectional view of a track section configuration in an embodiment of the invention;
FIG. 3 is an exploded view of a track load monitoring pad device in accordance with an embodiment of the present invention;
FIG. 4 is a perspective view of a load transfer column in an embodiment of the invention;
FIG. 5 is a perspective view of a sensor mounting plate in an embodiment of the invention;
FIG. 6 is a perspective view of a sensor mounting plate at different angles in an embodiment of the present invention;
FIG. 7 is a top view of a sensor mounting plate in an embodiment of the invention;
FIG. 8 is a flow chart of calibrating a piezoelectric sensor in an embodiment of the invention;
FIG. 9 is a graph showing the calibration results of a piezoelectric sensor according to an embodiment of the present invention;
FIG. 10 is a graph showing the calibration results of the acceleration sensor in test case one of the present invention;
FIG. 11 is a graph showing the calibration results of two pressure sensors of different resistances according to the first embodiment of the present invention;
FIG. 12 is a graph of the calibration results of two pressure sensors in test case one of the present invention;
FIG. 13 is a plot of acceleration versus vertical displacement measured by a acceleration sensor in test case two of the present invention;
FIG. 14 is a plot of voltage versus stress levels measured by a pressure sensor and a piezoelectric sensor in test case two of the present invention;
FIG. 15 is a graph showing test results of acceleration sensor in test example III of the present invention;
FIG. 16 is a graph showing the test results of the pressure sensor in test case III of the present invention;
FIG. 17 is a graph showing the results of the piezoelectric sensor in test example III according to the present invention.
Reference numerals:
a track load monitoring system 100; track load monitoring pad assembly 10; an upper cover plate 11; a sensor fixing plate 12; a fixed plate body 121; a sensor mounting groove 122; a circular through hole 1221; a support step 1222; wiring groove 123; a hub 1231; a joint accommodating part 1231a; a branch line part 1232; a counterbore 124; a piezoelectric sensor 13; a load transfer column 15; a first column portion 151; a second column section 152; screw mounting holes 153; a base plate 16; screw receiving holes 161; a fixing plate fastening screw 17; a base set screw 18; a lower foundation 20; a road bed board 30; a rail 40; a signal acquisition device 50; a calculation analysis device 60; a communication device 70; the terminal 71 is monitored.
Detailed Description
In order to make the technical means, creation characteristics, achievement of the purposes and effects of the present invention easy to understand, the track load monitoring pad device, system and calibration method thereof of the present invention will be specifically described with reference to the embodiments and the accompanying drawings.
< example >
Fig. 1 is a block diagram of the track load monitoring system in the present embodiment.
As shown in fig. 1, the track load monitoring system 100 includes a plurality of track load monitoring pad devices 10, a signal acquisition device 50, a calculation analysis device 60, a communication device 70, and a plurality of monitoring terminals 71.
Fig. 2 is a sectional view of the track portion structure in the present embodiment.
As shown in fig. 2, the track load monitoring pad device 10 is mounted directly to the lower portion of the ballast bed in the track structure and contacts the bottom of the ballast bed to carry the load. Rail 40 is a conventional i-rail. The structure of the rail 40 is conventional and will not be described in detail.
Fig. 3 is a structural exploded view of the track load monitoring pad device in this embodiment.
As shown in fig. 3, the rail load detecting pad device 10 includes an upper cover plate 11, a sensor fixing plate 12, a plurality of piezoelectric sensors 13, cables 14 thereof, a plurality of load transmitting columns 15, a base plate 16, a plurality of fixing plate fastening screws 17, and a plurality of base fixing screws 18. The piezoelectric sensors 13 are used for collecting analog piezoelectric signals under the road bed board 30, the upper cover plate 11, the sensor fixing plate 12 and the base plate 16 are used for accommodating and fixing the piezoelectric sensors 13 and cables thereof, and the load transfer columns 15 are arranged below the piezoelectric sensors 13 to play a role in load transfer and improve the stability of the piezoelectric sensors 13. Since the upper cover plate 11, the sensor fixing plate 12, and the base plate 16 are designed according to the structure of the piezoelectric sensor 13 and its cables, the structure of the piezoelectric sensor 13 and its cables will be described first.
The piezoelectric sensor 13 is a piezoelectric single crystal sensor of the prior art, and the model is PACEline 1-CLP/26kN. The piezoelectric sensor 13 is in a flat cylindrical shape as a whole, has a diameter of 35mm and an overall thickness of 3.5mm, and comprises a metal base and an annular sheet-shaped piezoelectric crystal, wherein the metal base is provided with an annular groove for installing the piezoelectric crystal, the piezoelectric crystal is embedded and fixed in the annular groove, and the upper surface of the piezoelectric crystal is exposed from the notch of the annular groove. The metal base is made of stainless steel, has corrosion resistance, can work safely for a long time in a very wide temperature range, and can be well suitable for various track scenes; the piezoelectric crystal is an annular quartz plate with the diameter of 18mm, and has good thickness deformation piezoelectric effect, high measurement precision and good sensitivity; and the dielectric constant and the temperature stability of the piezoelectric constant are good, so that the working temperature range of the piezoelectric sensor 13 is wide, and the piezoelectric sensor is well applicable to various track scenes. The force capacity range of the piezoelectric sensor 13 is 0-26 kN, the working environment temperature is-20-120 ℃, and the deformation range is 0-3.5 mu m.
The upper cover plate 11 is a steel member, the bottom of the upper cover plate 11 is a plane, and in order to avoid damaging the piezoelectric crystal of the piezoelectric sensor 13, the bottom of the upper cover plate 11 is provided with a rubber cushion layer. In addition, in order to ensure that the piezoelectric sensor 13 can detect obvious piezoelectric signals to ensure measurement accuracy, the cushion layers at the bottom of the upper cover plate 11 are all rubber cushion plates with medium rigidity, and the rigidity is more than or equal to 30kN/mm.
Fig. 4 is a perspective view of the load transfer column in this embodiment.
As shown in fig. 4, the load transmission column 15 includes a first column portion 151 and a second column portion 152 which are integrally formed, each having a cylindrical shape, wherein the first column portion 151 has a larger diameter than the second column portion 152, thus forming a stepped structure at the connection position of the two. The load transmission column 15 has a screw mounting hole 153 penetrating through the middle thereof, and the diameter of the screw mounting hole 153 gradually increases on the side near the end of the second column portion 152. The base fixing screw 18 is a countersunk screw, and the shape of the screw mounting hole 153 is matched with that of the base fixing screw 18.
Fig. 5 to 7 are perspective views and top views of two different angles of the sensor fixing plate according to the present embodiment.
As shown in fig. 5 to 7, the sensor fixing plate 12 is a steel plate including a fixing plate body 121, a plurality of sensor mounting grooves 122, a wiring groove 123, and a plurality of countersinks 124.
The fixing plate body 121 is rectangular, four corners of the fixing plate body are provided with chamfers, and the thickness of the fixing plate body 121 is 10 mm-15 mm. The length and width of the fixing plate body 121 are identical to those of the upper cover plate 11.
The sensor mounting grooves 122 are cylindrical holes, are distributed at the corners or edges of the fixed plate body 121, have diameters and depths matched with those of the piezoelectric sensors 13, and are opened upwards after the mounting is completed. In this embodiment, the number of the sensor mounting grooves 122 is 6, and six sensor mounting grooves 122 are symmetrically distributed on two sides along the central axis of the length direction of the fixing plate body 121, and three sensor mounting grooves 122 on the same side are equally spaced. I.e. when mounted under the track bed board 30, six piezo-electric sensors 13 are symmetrically distributed under the track bed board 30. As shown in fig. 5 to 7, the bottom of the sensor mounting groove 122 has a circular through hole 1221, the diameter of the circular through hole 1221 is slightly smaller than the inner diameter of the sensor mounting groove 122, and a ring of supporting steps 1222 for supporting and limiting the load transmission column 15 is formed at the bottom of the sensor mounting groove 122.
The wiring groove 123 is used for accommodating and fixing the cable 14, so as to avoid the influence of poor contact, falling off and the like caused by displacement and the like in the running process of the train on signal acquisition. The wiring groove 123 is disposed on one surface of the fixing plate body 121, and includes a wire collecting portion 1231 and a plurality of branch line portions 1232.
The wire collecting portion 1231 is located in the middle of the fixing plate body 121 and extends along the length direction of the fixing plate body 121, and a cross section of the wire collecting portion is rectangular and is used for accommodating a plurality of cables 14. One end of the wire collecting portion 1231 communicates with one side of the fixing plate body 121 in the longitudinal direction, and a joint accommodating portion 1231a is provided at the one end, and the joint accommodating portion 1231a has a semicircular cross section.
One end of each branch line portion 1232 communicates with one sensor mounting groove 122, the other end communicates with the line concentration portion 1231, and each branch line portion 1232 extends in the width direction of the fixing plate body 121, i.e., perpendicularly to the line concentration portion 1231. The connection position of the branch line portion 1232 and the wire collecting portion 1231 has a chamfer to prevent the cable 14 from being damaged by the sharp corner. The branch line portion 1232 is rectangular in cross section and smaller in size than the cross section of the line concentrating portion 1231.
Four counter bores 124 are formed at both ends of the fixing plate body 121 in the longitudinal direction in a divided manner in two groups for mounting fastening screws to fix the sensor fixing plate 12 and the upper cover plate 11 together. The nut of the fastening screw is fitted into the counterbore 124 so that the bottom surface of the sensor mounting plate 12 remains flat after the screw is installed.
The upper cover plate 11 and the sensor fixing plate 12 are fixedly connected through fastening screws 17 at the positions of four counter bores 124.
The base plate 16 is a rectangular steel plate, and has chamfers at four corners, and its length and width are also identical to those of the fixed plate body 121.
A plurality of screw receiving holes 161 are formed at both sides of the width direction of the base plate 16 for connecting the load transmission posts 15 fixedly installed in the respective sensor installation grooves 122. In this embodiment, the number of the screw receiving holes 161 is six, the distribution of which corresponds to the six sensor mounting grooves 122, and after the mounting is completed, the screw receiving holes 161 are located on the central axis of the corresponding sensor mounting groove 122, and the aperture of the upper end (i.e., the end near the sensor fixing plate 12) of the screw receiving holes 161 is smaller than the aperture of the lower end (i.e., the end near the lower foundation 20). The screw receiving hole 161 has a trapezoidal cross section in a side view, and can be connected with the screw mounting hole 153 at the bottom of the load transmission column 15 to form a counterbore-like structure in which the base fixing screw 18 is mounted, so that the bottom surface of the base plate 16 is flat after the base fixing screw 18 is mounted.
As described above, the bottom of the sensor mounting groove 122 has the circular through hole 1221, and the second column portion 152 of the load transmission column 15 is fitted in the circular through hole 1221, so that the piezoelectric sensor 13 is prevented from being damaged due to a large load and a small contact area, and therefore the base plate 16 made of steel and having a certain thickness is provided below the sensor fixing plate 12 and below the load transmission column 15.
After the completion of the installation, the six piezoelectric sensors 13 and the six load transmission posts 15 are fitted into the six sensor mounting grooves 122, respectively, and the cables thereof are accommodated in the wiring grooves 123. The bottom of the load transmission column 15 (i.e., the bottom of the second column 152) abuts against the base plate 16, and is fixed and laterally limited by the base fastening screw 18, the first column 151 of the load transmission column 15 abuts against the support step 1222 at the bottom of the sensor mounting groove 122, and the second column 152 is fitted in the circular through hole 1221. The bottom of the piezoelectric sensor 13 is abutted with the upper end of the load transmission column 15, and the upper surface of the quartz plate exposed from the upper end is abutted with the cushion layer at the bottom of the upper cover plate 11, so that the piezoelectric sensor 13 is kept stable in the monitoring process.
The cables of each piezoelectric sensor 13 are accommodated in the wiring portion 123, specifically, the cables extend from the corresponding branch line portions 1232 to the line collecting portion 1231, extend along the line collecting portion 1231, and finally extend from one side in the longitudinal direction of the fixing plate body 121, and the adapter connected to the cables is fitted and fixed to the adapter accommodating portion.
The signal acquisition device 50 comprises a plurality of signal acquisition instruments, and each signal acquisition instrument is respectively connected with each piezoelectric sensor 13 and is used for acquiring piezoelectric signals measured by the piezoelectric sensors 13.
The computational analysis device 60 is communicatively coupled to the signal acquisition device 50, receives the piezoelectric signal from the signal acquisition device 50 and performs computational analysis thereon.
The plurality of monitoring terminals 71 are communicatively connected to the calculation and analysis device 60 via the communication device 70, and acquire the acquired digital signals and calculation and analysis results from the calculation and analysis device 60, and display them.
Fig. 8 is a flowchart of calibration of the piezoelectric sensor in the present embodiment.
In order to improve measurement accuracy and ensure that each piezoelectric sensor 13 can record a high-quality signal, before measurement is performed, the piezoelectric sensor 13 needs to be calibrated for a target load range, and as shown in fig. 8, a flow for calibrating the piezoelectric sensor 13 specifically includes the following steps:
in step S1, the piezoelectric sensor 13 is attached to the surface of the resin pad, and its cable is connected to the data recorder.
In this embodiment, the resin pad is square, the length and width of which are 100mm, and the thickness of which is 7mm, and the upper surface of the quartz plate of the piezoelectric sensor 13 is attached to the lower surface of the resin pad. Arduino was used as a microcontroller and a data logger was used in electrical connection with it, to which the cable of piezoelectric sensor 13 was connected. The data logger is able to directly measure the voltage of the piezoelectric crystal due to vibration of the surface on which the material (i.e., the resin pad) is placed.
In step S2, a series of test loads are applied to the resin pad above the piezoelectric sensor 13 by the rectangular actuator, and corresponding piezoelectric signals measured by the piezoelectric sensor 13 are recorded by the data logger.
To avoid damaging the quartz plate, the test load is not applied directly to the piezoelectric sensor 13, but to the resin pad, by a rectangular actuator on the resin pad 1cm from the quartz plate surface of the piezoelectric sensor 13. In this embodiment, the rectangular actuator has an end section for applying a load of 60mm in length and 40mm in width.
The series of test loads applied have different frequencies and different stress levels.
Step S3, the pressure value of the piezoelectric signal measured by the piezoelectric sensor 13 is calibrated with reference to the parameter of the applied test load.
FIG. 9 is a diagram showing the calibration result of the piezoelectric sensor according to the present embodiment, wherein FIG. 9 (a) is a plot of voltage value versus stress of the piezoelectric sensor after calibration; fig. 9 (b) is a waveform diagram of signals measured by the piezoelectric sensor after calibration.
In the present embodiment, as shown in fig. 9 (a), the test load has a frequency of 0 to 10Hz and a stress level of 0 to 5000kPa, and the calibration is performed by using such a test load, and the calibration result shows that the signal measured by the piezoelectric sensor 13 has a linear correlation with the stress level. As shown in fig. 9 (b), after calibration, the signal measured by the piezoelectric sensor 13 under a load of 5kN, 5Hz shows a good correlation with the applied test load, indicating that the accuracy of the measured load is high.
After calibration is completed, the piezoelectric sensor 13 can be installed into the track load monitoring pad device 10 for actual track monitoring.
Example operation and Effect
According to the track load monitoring pad device 10 and the track load monitoring system 100 provided in the present embodiment, the track load monitoring pad device 10 is installed under the track bed board 30, and includes a plurality of piezoelectric sensors 13, so that the load of the track can be monitored by the piezoelectric sensors 13 directly integrated in the track structure. The piezoelectric sensor 13 has the advantages of high sensitivity, high signal-to-noise ratio, reliable operation, simple structure and the like, can detect and obtain high-quality signals, and the strength of the piezoelectric signals detected by the piezoelectric sensor is in linear relation rather than exponential relation with the stress level born by the steel rail, so that the signals detected by the track load monitoring backing plate device can still effectively identify the load change even under the condition of high load, and the track load monitoring backing plate device has wide application range and can be suitable for various track conditions. Further, since the sensor fixing plate 12 is installed between the upper cover plate 11 and the base plate 16, the piezoelectric sensor 13 and the load transfer column 15 are installed in the sensor installation groove 122 of the sensor fixing plate 12, the piezoelectric sensor 13 is fixed and limited in such a manner, and displacement, falling and other conditions of the piezoelectric sensor 13 caused by rail vibration during train operation can be avoided, so that monitoring effect during train operation is ensured.
According to the calibration method of the track load monitoring pad device 10 of the present embodiment, the piezoelectric sensor 13 is attached to the surface of the resin pad, and a series of test loads are applied by the rectangular actuators to calibrate the piezoelectric sensor 13. By doing so, the piezoelectric sensor 13 can detect a signal of better quality and better accuracy in the target load range, and damage to its piezoelectric crystal can be avoided.
In the embodiment, the piezoelectric sensor 13 is a single crystal sensor adopting an annular quartz plate, and the quartz crystal has good thickness deformation piezoelectric effect, high measurement precision and good sensitivity; and the dielectric constant and the temperature stability of the piezoelectric constant are good, so that the working temperature range of the piezoelectric sensor 13 is wide, and the piezoelectric sensor is well applicable to various track scenes.
In the embodiment, the cushion layer at the bottom of the upper cover plate 11 is a middle-rigidity rubber cushion plate, and the high-rigidity cushion plate has higher wave propagation capability, so that the piezoelectric sensor 13 can monitor and obtain larger signal amplitude in cooperation, thereby being beneficial to monitoring load change and subsequent calculation and analysis.
In an embodiment, the rail load monitoring pad apparatus 10 may be integrated into a rail for long term use without removal after one test.
Test example 1
In this test example, calibration tests were performed on three sensors to evaluate their likelihood of monitoring track performance.
While most sensors have typically been calibrated to some degree by the manufacturer, to ensure that each sensor is able to record a high quality signal, in this test case, three sensors are recalibrated for the target load range.
The three sensors are an acceleration sensor (accelerometer), a pressure sensor and the piezoelectric sensor. The accelerometer is used for measuring vibration change of the target; the pressure sensor is used for measuring the change of the stress level on the target; piezoelectric sensors are used to measure changes in wave transmission into a target, thereby detecting changes in the performance of the target. The parameters of the piezoelectric sensor are as described above and are not repeated; the parameters of the other two sensors are shown in tables 1 and 2:
TABLE 1 parameter table of acceleration sensor
Table 2 pressure sensor parameter table
For the accelerometers, each accelerometer was fixed on an actuator of a laboratory hydraulic machine and 1000 vibration wave sequences were applied at each test load, the acceleration signals measured at the different vibration waves were recorded, and the measured signals were compared with the displacement produced by the actuator of the hydraulic machine. In this test example, the test load has different frequencies and amplitudes, the frequencies are 0-10 Hz, and the amplitudes are 0-3 mm. The measured acceleration amplitude (displacement) is compared with the displacement of the actuator at 5Hz, at 1.5mm etc.
FIG. 10 is a graph showing the calibration results of the acceleration sensor in the present test example, wherein FIG. 10 (a) is a plot of the amplitude of the acceleration measured by the acceleration sensor after calibration versus the amplitude; fig. 10 (b) is an exemplary graph of acceleration signals measured by two acceleration sensors after calibration.
As shown in fig. 10, ACC1 exhibits a good correlation between acceleration and displacement waves, enabling discrimination between different pulses.
For a pressure sensor, it is attached to a 150mm by 150mm thick 50mm metal backing plate and a series of test loads are applied to the pressure sensor, the test loads having different frequencies and stress levels, the frequencies being 0 to 10Hz and the stress levels being 0 to 5000kPa. Since the signal of the pressure sensor depends on the resistance used in the microcontroller (i.e. the resistance in the measurement circuit), the resistance used is changed and the calibration test described above is repeated.
FIG. 11 is a graph of calibration results for two pressure sensors of this test example having different resistance values.
As shown in fig. 11, in the present embodiment, the resistance value was changed in kΩ units and a calibration test was performed, and the decrease in the resistance value resulted in a decrease in the amplitude value of the voltage measured by the two pressure sensors, and a logarithmic correlation was exhibited between the measured voltage and the applied stress level. For the same resistance value (1 kΩ for example), PR2 measures a higher voltage value, which indicates that the ability of PR2 to measure high level stress is relatively lower, limiting its applicability.
Fig. 12 is a graph of the calibration results of the two pressure sensors in this test example, in which fig. 12 (a) is a plot of the voltage values and stress levels of the two pressure sensors after calibration, and fig. 12 (b) is a graph of the signal waveforms measured by the two pressure sensors after calibration.
As shown in fig. 12 (a), the voltage value measured by the pressure sensor has a logarithmic correlation with the stress. At the same stress level, the voltage measured by PR2 is higher than PR1, the signal measured by PR1 is independent of the frequency of the test load, and as the test load frequency increases, the voltage measured by PR2 increases slightly. As shown in fig. 12 (b), at a test load of 5Hz and 5kN, the signal waveform measured by the pressure sensor is clear, and relatively speaking, the signal measured by PR1 is more accurate, and the frequency deviation from the test load is small.
For piezoelectric sensors, the above-described flow steps are used for calibration.
It can also be seen from fig. 9 (a) that the signal measured by the piezoelectric sensor shows a linear dependence on the stress level, so that load changes at high load levels can be distinguished more clearly. Similar to PR1, the dependence of the piezoelectric crystal on the pulse frequency is also small, so that stress variations in the component can be monitored more clearly, irrespective of train speed. As can be seen from fig. 9 (b), the signal quality of the piezoelectric crystal is high, and different pulses can be distinguished.
In addition, the waveform quality measured by the pressure sensor and the piezoelectric sensor is better than that measured by the acceleration sensor.
Thus, with this test case, the following conclusions can be drawn:
the signal quality measured by the pressure sensor and the piezoelectric sensor is superior to that measured by the acceleration sensor;
the signal measured by the pressure sensor shows a logarithmic relationship with the stress level, limiting its ability to detect load changes at higher load levels;
the linear relation between the signal and the stress level measured by the piezoelectric sensor can be displayed, so that the load change under the high load level can be detected better.
< test example two >
In this test example, the suitability of the above three sensors in different types of rail pad was tested. The test is performed by a simulation test system which comprises a rubber plate, a concrete block, a metal section and a backing plate and is used for simulating a track bed, a sleeper, a steel rail and a rail lower backing plate respectively. The materials and parameters of each structural simulation member are shown in tables 3 and 4.
Table 3 test structure parameter table
Table 4 under-rail pad parameter table
And simulating a track structure, and sequentially placing a rubber plate, a concrete block, a rail lower backing plate and a metal section on the ground.
The pressure sensor is directly adhered to the upper surface of the rail pad, and the detection end of the pressure sensor is directly contacted with the bottom of the steel rail.
The accelerometer and the piezoelectric sensor are embedded in the rail pad groove on the lower surface of the rail pad plate, so that the accelerometer and the piezoelectric sensor are prevented from being damaged due to direct contact with the steel rail. In the test example, a circular rail pad groove with the diameter of 35mm and the depth of 3.5mm is formed in the middle of the lower surface of the rail pad plate.
During the measurement, a series of test loads are applied to the metal profile used to simulate the rail, and the signals measured by the various sensors are recorded. In this test example, the test load frequency was 5Hz and the stress level was 0 to 2000kPa.
FIG. 13 is a plot of acceleration versus vertical displacement measured by the acceleration sensor in this example.
As shown in fig. 13, the simulation test system (metal profile-rail pad-concrete block-rubber plate) produced a vertical displacement of 0 to 1mm at different stress levels. The difference in signals recorded by the acceleration sensor is small for different types of rail pad.
Fig. 14 is a line graph of voltage versus stress level measured by the pressure sensor and the piezoelectric sensor in this test example, where PI represents the piezoelectric sensor.
As shown in fig. 14, similarly, the voltage value measured by the piezoelectric sensor is linearly related to the stress level, while the voltage value measured by the pressure sensor is logarithmically related to the stress level.
In addition, for the high stiffness pad, the voltage values recorded by the pressure sensor and the piezoelectric sensor are higher, while when the medium and low stiffness pad is used, the voltage values measured by the pressure sensor and the piezoelectric sensor are the lowest, namely, higher signal amplitude can be obtained on the high stiffness pad.
Thus, with this test case, the following conclusions can be drawn:
the signal measured by the acceleration sensor is irrelevant to the type of the rail pad;
the signals measured by the pressure sensor and the piezoelectric sensor depend on the type of the rail pad, a higher signal amplitude is obtained on the high-stiffness pad, which has a higher stress concentration for the pressure sensor and a higher wave propagation capacity for the piezoelectric sensor. So that both are suitable for the rail pad with medium and high rigidity.
Test case III
In the test example, the monitoring capability of the three sensors on different track running conditions is tested. The track structure was also simulated by a simulation test system, and the test was performed with parameters of each structure simulation part as shown in table 5.
Table 5 table for testing structural parameters
The parameters of the rail pad are the same as those in the second embodiment, and the description thereof will not be repeated.
That is, the test structure of the present test case is basically the same as that of the second test case, except that the rubber sheet for simulating the ballast bed in the structure of the second test case is replaced with the first rubber sheet and the second rubber sheet of the present test case, respectively.
By simulating the rail pad with different types of pads, by simulating the ballast bed with the first rubber sheet or the second rubber sheet described above, a plurality of simulation test systems can be constructed.
The pressure sensor is directly adhered to the upper surface of the rail pad, and the detection end of the pressure sensor is directly contacted with the bottom of the steel rail.
The accelerometer and the piezoelectric sensor are embedded in the rail pad groove on the lower surface of the rail pad plate, so that the accelerometer and the piezoelectric sensor are prevented from being damaged due to direct contact with the steel rail. In the test example, a circular rail pad groove with the diameter of 35mm and the depth of 3.5mm is formed in the middle of the lower surface of the rail pad plate. I.e., the method of installing the three sensors in the system is the same as in test case two.
In this embodiment, two tests were performed on the above simulation test system:
according to the test I, a test machine is adopted to apply a preset loading sequence on each simulation test system, the loading sequence consists of a series of loads with stress of 0-2000 kPa, and different simulation test systems can be deformed to different degrees by the loading sequence, so that the condition that trains with different weights pass through different tracks is simulated, and vibration of the system is monitored by an acceleration sensor.
And secondly, testing, namely applying a series of different displacements to each simulation test system by using a testing machine, wherein the displacements are between 0 and 0.8mm, so that the deformation of the rail when a train passes through is simulated, and monitoring the stress change of the system by using a pressure sensor and a piezoelectric sensor respectively.
FIG. 15 is a graph of test results of acceleration sensors in the present test example, wherein FIG. 15 (a) is a graph of test results of test one, showing acceleration values measured by loading 500kPa, 1000kPa, 1500kPa stress on different systems, respectively; fig. 15 (b) is a test result diagram of test two, showing a measured pulse waveform diagram.
As shown in fig. 15 (a), the acceleration sensor is able to identify the different stress levels applied (i.e. simulate trains of different weights) while also being able to distinguish the differences between the different systems (the system employing a medium stiffness substrate and the system employing a low stiffness substrate) and thus to measure higher accelerations on the low stiffness substrate system expected to produce higher displacements. As shown in fig. 15 (b), the pulse quality measured by the acceleration sensor is poor.
FIG. 16 is a graph of the test results of the pressure sensor in this test example, wherein FIG. 16 (a) is a graph of the test results of test one, showing voltage values measured by applying displacement measurements of 0.25mm, 0.5mm, and 0.8mm, respectively, on different systems; fig. 16 (b) is a test result diagram of test two, showing a measured pulse waveform diagram.
FIG. 17 is a graph of the test results of the piezoelectric sensor in this test example, wherein FIG. 17 (a) is a graph of the test results of test one, showing voltage values measured by applying displacement measurements of 0.25mm, 0.5mm, and 0.8mm, respectively, on different systems; fig. 17 (b) is a test result diagram of test two, showing a measured pulse waveform diagram, in which PI represents a piezoelectric sensor.
As shown in fig. 16 (a) and 17 (a), the pressure sensor and the piezoelectric sensor can identify different stress levels required for applying different displacements, and can clearly distinguish different analog test systems (a system using a medium-stiffness substrate and a system using a low-stiffness substrate), that is, can be applied to monitor an actual track structure, and can clearly distinguish different track system types. Furthermore, both the pressure sensor and the piezoelectric sensor show a reduced signal amplitude when switching from a system employing a medium stiffness substrate to a system employing a low stiffness substrate.
As shown in fig. 16 (b) and 17 (b), the pulse can be clearly identified by using the pressure sensor and the piezoelectric sensor, and the waveform similar to the waveform acquired by the standard instrument of the testing machine can be measured, so that the signal quality is good. And relatively speaking, the signal of the piezoelectric sensor is clearer.
Thus, with this test case, the following conclusions can be drawn:
the signal quality of the pressure sensor and the piezoelectric sensor is better than that of the acceleration sensor;
the pressure sensor and the piezoelectric sensor can monitor the track performance change caused by traffic conditions or track support strength change, especially when the middle-high rigidity track pad is used;
the piezoelectric sensor provides the clearest signal output.
Therefore, based on the test and analysis of the test cases, the embodiment adopts a plurality of piezoelectric sensors, the signal quality obtained by monitoring is good, and the track performance change caused by the traffic condition or the track supporting strength change can be effectively monitored.
The above examples are only for illustrating the specific embodiments of the present invention, and the present invention is not limited to the description scope of the above examples.
Claims (9)
1. A track load monitoring pad device installed between a ballast bed plate and a lower foundation of a ballastless track for monitoring a load under the ballast bed plate, comprising:
a base plate mounted on the lower foundation;
the sensor fixing plate is arranged on the base plate and provided with a plurality of upward opening sensor mounting grooves;
the upper cover plate is arranged on the sensor fixing plate, and the bottom of the upper cover plate is provided with a cushion layer made of rubber;
the piezoelectric sensors are respectively arranged in the sensor mounting grooves; and
a plurality of load transfer columns respectively installed in the sensor installation grooves and positioned below the piezoelectric sensors,
the piezoelectric sensor comprises a flaky piezoelectric crystal, the upper surface of the piezoelectric crystal is abutted against the cushion layer at the bottom of the upper cover plate, and the strength of a piezoelectric signal detected by the piezoelectric sensor is in a linear relation with the stress level of the steel rail.
2. The track load monitoring pad device of claim 1, wherein:
wherein the piezoelectric sensor is PACEline 1-CLP/26kN, and the force capacity range is 0-26 kN.
3. The track load monitoring pad device of claim 1, wherein:
wherein the piezoelectric sensor is cylindrical in shape, and further comprises a metal base with an annular groove,
the piezoelectric crystal is an annular sheet-shaped quartz plate, the annular sheet-shaped quartz plate is embedded and installed in the annular groove of the metal base, and the upper surface of the quartz plate is abutted to the cushion layer at the bottom of the upper cover plate.
4. A track load monitoring pad device in accordance with claim 3, wherein:
wherein the diameter of the piezoelectric sensor is 35mm, the thickness is 3.5mm,
the diameter of the quartz plate is 18mm,
the working environment temperature of the piezoelectric sensor is-20-120 ℃, and the deformation range is 0-3.5 mu m.
5. The track load monitoring pad device of claim 1, wherein:
wherein the sensor fixing plate is in a cuboid shape,
the number of the sensor mounting grooves is plural, the sensor mounting grooves are distributed at the corner or the edge of the sensor fixing plate,
the piezoelectric sensor is connected with a cable,
the sensor fixing plate is also provided with a wiring groove which is communicated with all the sensor mounting grooves and is communicated with the side edge of the sensor fixing plate,
the cable extends in the wiring groove and extends from the side edge of the sensor fixing plate.
6. The track load monitoring pad device of claim 1, wherein:
wherein the base plate, the sensor fixing plate and the upper cover plate are all cuboid steel plates, the lengths and the widths of the base plate, the sensor fixing plate and the upper cover plate are consistent,
the thickness of the sensor fixing plate is 10 mm-15 mm.
7. A track load monitoring system, comprising:
the track load monitoring backing plate device is arranged below a ballast bed plate of the ballastless track and is used for monitoring the load below the ballast bed plate to obtain a corresponding piezoelectric signal;
the signal acquisition device is connected with the track load monitoring backing plate device and is used for acquiring the piezoelectric signals measured by the track load monitoring backing plate device; and
the calculation and analysis device is in communication connection with the signal acquisition device and is used for acquiring the piezoelectric signal from the signal acquisition device and carrying out calculation and analysis,
wherein the rail load monitoring pad arrangement is the rail load monitoring pad arrangement of any one of claims 1-6.
8. A method of calibrating a rail load monitoring pad assembly as claimed in any one of claims 1 to 6, comprising the steps of:
step S1, attaching a piezoelectric sensor for the track load monitoring pad device on the surface of a resin pad, and connecting a cable of the piezoelectric sensor to a data recorder;
s2, applying a series of test loads on the resin backing plate above the piezoelectric sensor through a rectangular actuator, and recording piezoelectric signals measured by the piezoelectric sensor through the data recorder;
and step S3, calibrating the pressure value corresponding to the piezoelectric signal by referring to the applied parameter of the test load.
9. The method of calibrating according to claim 8, wherein:
wherein in the step S1, the length and the width of the resin backing plate are 100mm, the thickness is 7mm,
in the step S2, the section length of the rectangular actuator is 60mm, the section width is 40mm,
in step S2, a series of said loads have different frequencies in the range of 0-10 Hz and different stress levels in the range of 0-5000 kPa.
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