JP7148452B2 - Method and apparatus for estimating deterioration state of bridge joints - Google Patents

Description

The present invention relates to a method and apparatus for estimating the state of deterioration of bridge joints.

Conventionally, expansion joints for roads (hereinafter referred to as bridge joints) have been installed in the middle of bridges and at the joints at the ends of bridges on the road side in order to absorb expansion and contraction due to changes in temperature and deformation due to the running of automobiles. there is
Bridge joints are often made of steel or rubber, but steel joints make a lot of noise when cars pass by, and rubber joints have problems with durability. A steel plate reinforced rubber joint is used in which a reinforcing plate made of a steel plate is inserted into the rubber.
Hereinafter, "bridge joint" refers to this steel plate reinforced rubber joint.
8A and 8B are diagrams showing an example of a bridge joint 50, where FIG. 8A is a plan view and FIG. 8B is a sectional view taken along line AA of FIG. 8A. In addition, (a) the white arrow indicates the extension direction of the road.
The bridge joint 50 includes a rubber 51 that is a joint body, a first reinforcing plate (top plate 52) arranged on the surface side (road side) of the rubber 51, and a second reinforcing plate (top plate 52) arranged on the back side ( A bottom plate 53) and a third reinforcing plate (side plate 54) arranged on the side surface of the rubber 51 are provided.
On the surface side and the back side of the rubber 51, expansion grooves 55 and 56 are formed extending in the extension direction of the road surface, which is the length direction of the bridge joint 50. As shown in FIG.
Deterioration of the bridge joint 50 shown in the figure mainly includes separation between the rubber 51 and the top plate 52 which is a reinforcing plate.

Currently, the state of deterioration of bridge joints is estimated by workers visually checking the joints or by hitting them with a hammer.
However, this method requires work under traffic regulations, which not only takes time and money, but also makes it difficult to predict deterioration because the internal rubber and reinforcing plates peel off and progress. Therefore, workers with extensive work experience were required.
On the other hand, as a method of estimating the state of deterioration of bridge joints, multiple microphones and analysis equipment were installed around the road on which the bridge joints were installed, and the passing sound, which is the sound of vehicles passing through the bridge joints, was collected. A method has been proposed for estimating whether or not the reinforcing plate and the rubber are separated from the frequency characteristics of the passing sound (for example, see Patent Document 1).

JP 2017-43147 A

However, in Patent Document 1, it is necessary to install a plurality of microphones and analysis devices in the vicinity of each bridge joint. Accuracy was not good enough.
In addition, it was not an efficient method because data collection and microphone maintenance were difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple method for accurately estimating the deterioration state of a bridge joint.

The present invention is a method for estimating the state of deterioration of a bridge joint in which a reinforcing plate is arranged inside a rubber member, wherein a tire acceleration sensor, which is an acceleration sensor attached to a tire, measures the road surface on which the bridge joint is installed. a step of detecting a tire acceleration waveform, which is an acceleration waveform input from a step of obtaining tire acceleration information as a characteristic quantity of the tire acceleration waveform from the detected tire acceleration waveform; and tire acceleration information when the tire acceleration sensor passes through the deteriorated bridge joint obtained in advance, and estimating the deterioration state of the bridge joint from the comparison result. Characterized by
As a result, it is possible not only to estimate the state of deterioration of bridge joints without installing equipment such as microphones and analysis equipment around the road, but also to accurately estimate the state of deterioration of bridge joints even if there is noise in the surroundings.

It should be noted that the summary of the invention does not list all the necessary features of the present invention, and subcombinations of these feature groups can also be inventions.

It is a figure which shows the degradation state estimation apparatus of the bridge joint which concerns on this Embodiment. It is a figure which shows an example of the detected tire acceleration waveform. It is a figure which shows an example of the tire acceleration waveform which passed the low-pass filter. It is a figure which shows an example of a tire acceleration waveform and an unsprung acceleration waveform. 4 is a flowchart showing deterioration state estimation of a bridge joint; It is a figure which shows the setting method of a cut-off frequency. FIG. 4 is a diagram showing a relationship between an extracted frequency domain and an RMS value of acceleration; It is a figure which shows an example of a steel plate reinforcement type rubber joint.

FIG. 1 is a functional block diagram of a deterioration state estimating device for bridge joints (hereinafter referred to as a joint deterioration estimating device 10) according to the present embodiment, and a diagram showing the arrangement of acceleration sensors.
The joint deterioration estimating device 10 includes a first acceleration sensor 11 as a tire acceleration sensor, a wheel speed sensor 12, a second acceleration sensor 13 as an unsprung acceleration sensor, a determination waveform extraction means 14, and a first A joint deterioration monitoring vehicle (hereinafter simply referred to as a vehicle ) to determine whether or not the vehicle has passed a bridge joint, and to estimate the state of deterioration of the bridge joint that has passed.
Each means from the determination waveform extracting means 14 to the joint deterioration state estimating means 19 is composed of, for example, computer software and storage devices such as RAM and ROM.
The first acceleration sensor 11 is integrally arranged in a substantially central portion of the tire air chamber 20b side of the inner liner portion 20a of the tire 20 so that the detection direction is in the tire circumferential direction. A time-series waveform of acceleration (hereinafter referred to as a tire acceleration waveform) is detected.
The wheel speed sensor 12 is mounted on the knuckle 21 and detects the rotational speed of the wheel (hereinafter referred to as wheel speed). A well-known electromagnetic induction type wheel speed sensor or the like that includes a yoke that forms a circuit and a coil that detects changes in the magnetic flux of the magnetic circuit can be used.
The second acceleration sensor 13 is mounted on the knuckle 21 so that the detection direction is in the vertical direction of the vehicle. Acceleration waveform) is detected. Note that the detection direction of the second acceleration sensor 13 may be the vehicle front-rear direction.
The knuckle 21 is a non-rotating member under a vehicle spring that is rotatably connected via a hub 24 to an axle 23 that is connected to a wheel 22 of a tire 20. The knuckle 21 is connected to an upper arm 25 on the upper side and It is connected to the lower arm 26 . Reference numeral 27 is a shock absorber connected to the lower arm 26. FIG.
The output of the first acceleration sensor 11 is sent to the determination waveform extraction means 14, the output of the wheel speed sensor 12 is sent to the determination waveform extraction means 14 and the threshold value setting means 16, and the output of the second acceleration sensor 13 is sent to the determination waveform extraction means 14. 2 acceleration information acquisition means 17.

The determination waveform extracting means 14 includes a cutoff frequency setting section 14a and a low-pass filter 14b, and passes the tire acceleration waveform detected by the first acceleration sensor 11 through the low-pass filter 14b to determine deterioration. Extract the judgment waveform, which is the waveform of .
The cut-off frequency setting unit 14a converts the wheel speed detected by the wheel speed sensor 12 into the speed of the vehicle (hereinafter referred to as vehicle speed V) assuming that the vehicle is traveling at a constant speed, and cuts the low-pass filter 14b. The off-frequency _fc is set to a frequency corresponding to the vehicle speed V (here, 50 Hz to 150 Hz). The sampling frequency f _s may also be set for each vehicle speed V, but in this example, the sampling frequency f _s is set higher than the cutoff frequency f _c used in this example, such as about 1 kHz. If this is done, there is no need to change the sampling frequency _fs according to the vehicle speed V.
A method for setting the cutoff frequency _fc will be described later.
The low-pass filter 14b passes only the acceleration component having a frequency equal to or lower than the cutoff frequency f _c set by the cutoff frequency setting section 14a from the tire acceleration waveform detected by the first acceleration sensor 11 .

2(a) and 2(b) show acceleration waveforms in the tire circumferential direction (tire acceleration waveforms) detected by the first acceleration sensor 11. FIG. It is an acceleration waveform (hereinafter referred to as a detected waveform) detected when the joint A is passed. Also, FIG. (b) shows the detected waveform when passing through the bridge joint B where the rubber and the top plate are separated. In FIGS. 2(a) and 2(b), the vertical axis is the value of acceleration, and the unit is arbitrary [a. u. ]. Both bridge joints A and B are 20 years old.
Comparing these waveforms, the maximum amplitude of the waveform when passing through the bridge joint A shown in FIG. Overall, the waveform passing through the bridge joint B has more peaks and a larger amplitude than the waveform passing through the bridge joint A, although the peaks are larger than the peaks.
Also, as is clear from a comparison of FIGS. 2(a) and 2(b), the corrugations and the rubber and the top plate are separated when passing through the bridge joint A where the rubber and the top plate are not separated. It can be seen that the waveform shape itself is different from the waveform when passing through the bridge joint B. FIG.
On the other hand, FIGS. 3(a) and 3(b) show tire acceleration waveforms (hereinafter referred to as low-pass waveforms) passed through the low-pass filter 14b with a cutoff frequency of f _c =100 Hz. FIG. 2(b) is a low-pass waveform of the acceleration waveform detected when passing through the bridge joint B. FIG.
Comparing these waveforms, the waveform when passing through the bridge joint B shown in FIG. 3(b) has a larger amplitude than the waveform when passing through the bridge joint A shown in FIG. 3(a). It can be seen that there are many peaks.
In this way, both the detected waveform and the low-pass waveform are , are different in waveform shape itself.

The first acceleration information acquisition means 15 acquires acceleration information (tire acceleration information), which is a characteristic quantity for estimating the deterioration state of the bridge joint, from the filtered waveform, which is the determination waveform.
In this example, the RMS value S _a of the amplitude of the low-pass waveform is used as the tire acceleration information.
The threshold value setting means 16 sets a threshold value for estimating the deterioration state of the bridge joint. In this example, the threshold value is set according to the vehicle speed V detected by the wheel speed sensor 12 .
A threshold corresponding to the vehicle speed _V is hereinafter referred to as KV. This threshold value K _V corresponds to the acceleration information (acceleration information at the time of deterioration) when the vehicle passes through the deteriorated bridge joint obtained in advance according to the present invention.
A second acceleration information acquiring means 17 acquires unsprung acceleration information, which is a characteristic quantity for determining whether or not the vehicle has passed a bridge joint, from the unsprung acceleration waveform detected by the second acceleration sensor 13. do.
In this example, the RMS value _Sb of the amplitude of the unsprung acceleration waveform is used as the unsprung acceleration information.
4(a) and 4(b) are diagrams showing examples of tire acceleration waveforms and unsprung acceleration waveforms. When the tire 20 passes over the bridge joint 50, as shown in FIG. If the acceleration sensor 11 is located at the contact portion between the bridge joint 50 and the tire 20, the tire acceleration waveform indicated by the thick line in the figure and the unsprung acceleration waveform indicated by the thin line in FIG. appears. However, as shown in FIG. 4B, when the first acceleration sensor 11 is not in contact with the contact portion, a peak appears in the unsprung acceleration waveform due to the vibration of the bridge joint 50, but appears in the tire acceleration waveform. do not have.
Therefore, in order to determine whether or not the vehicle has passed through the bridge joint 50, unsprung acceleration information is required.

The passage determining means 18 first determines whether or not the RMS value S _b of the amplitude of the unsprung acceleration waveform acquired by the second acceleration information acquiring means 17 is equal to or greater than the unsprung threshold K _b which is a predetermined value. By doing so, it is determined whether or not the vehicle has passed through the bridge joint 50. Next, time _tb at which the peak of the unsprung acceleration waveform is detected, time _ta at which the peak of the tire acceleration waveform is detected, and is within _{a predetermined} time interval K _T , the first acceleration sensor 11 attached to the tire 20 receives the input from the bridge joint 50. It is determined whether the first acceleration sensor 11 has passed through the bridge joint 50 or not.
The RMS value S _b of the amplitude of the unsprung acceleration waveform and the determination result of the passage determining means 18 are sent to the joint deterioration state estimating means 19 .
The joint deterioration state estimation means 19 estimates the deterioration state of the bridge joint 50 only when the passage determination means 18 determines that the vehicle has passed the bridge joint 50 .
Specifically, by comparing the RMS value S _a of the amplitude of the low-pass waveform obtained by the first acceleration information obtaining means 15 and the threshold value K _V set by the threshold setting means 16, the deterioration of the bridge joint 50 is determined. Estimate the state.

Next, the operation of the joint degradation estimating device 10 will be described with reference to the flowchart of FIG.
First, the first acceleration sensor 11 detects the tire acceleration waveform, the second acceleration sensor 13 detects the unsprung acceleration waveform, and the wheel speed sensor 12 detects the wheel speed (step S10). .
Next, from the unsprung acceleration waveform, the RMS value _Sb of the amplitude of the unsprung acceleration waveform is calculated using the second acceleration information acquisition means 17 (step S11).
In step S12, the RMS value _Sb of the amplitude of the unsprung acceleration waveform and the unsprung threshold _Kb are compared. If _Sb < _Kb , the vehicle has not passed the bridge joint 50, so the process proceeds to step S13 and the estimation of the deterioration state of the bridge joint 50 is stopped.
On the other hand, _if S _b ≧K _b , it is determined that the vehicle has passed the bridge joint 50, and the process proceeds to step S14. It is determined whether or not the time difference (|t _a −t _b |) from the detected time t _a is within a predetermined time interval K _T .
If |t _a −t _b |≦K _T , it is determined that the first acceleration sensor 11 has passed through the bridge joint 50, and by performing the processes of steps S15 to S19 described later, the deterioration of the bridge joint 50 is detected. Estimate the state.
On the other hand, if |t _a −t _b |>K _T , the first acceleration sensor 11 is not in the contact portion between the tire 20 and the bridge joint 50, so the process proceeds to step S13, where the bridge joint 50 deteriorates. Stop estimating state.

Next, the processing of steps S15 to S19 will be described.
At step S15, the wheel speed detected at step S10 is converted into a vehicle speed, and at step S16, the cutoff frequency fc of the low-pass filter 14b and the threshold value _Kv are set based on the vehicle speed _V obtained above.
In this example, the cut-off frequency fc when the vehicle speed is 60 km/hr is 100 Hz, and the cut-off frequency fc when the vehicle speed is V km/hr is _fc = 100 _{x (} V/60) [Hz]. did. That is, the cutoff frequency fc is set to a value proportional to the vehicle speed V. _FIG .
The reason why the cutoff frequency _fc is set to 100 Hz when the vehicle speed is 60 km/hr will be described below.
When the vehicle speed is 60 km/hr, the distance traveled by the vehicle in (1/100) _seconds is defined as the reference space scale L ₀ . The frequency (reference spatial scale frequency) with the scale L ₀ as the wavelength is 100 Hz.
In this example, only frequency components lower than 100 Hz are extracted from the acceleration waveform and used as the determination waveform. That is, if the wavelength at the frequency _fk is the spatial scale _Lk , only the components having the spatial scale _Lk wavelength longer than the reference spatial scale _L0 are extracted and used as the determination waveform.
Further, when the vehicle speed is 30 km/hr, as shown in FIG. 6(b), the time the vehicle travels by the reference space scale _L0 is twice as long (0.02 seconds) as when the vehicle speed is 60 km/hr. Therefore, the reference spatial scale frequency is 50 Hz. Therefore, when the vehicle speed is 30 km/hr, the cutoff frequency _fc should be set to 50 Hz.
That is, the cutoff frequency fc when the vehicle speed is _Vkm /hr should be fc = 100 _x (V/60) [Hz].
On the other hand, the threshold value K _V is set to a larger value as the vehicle speed V increases.
In step S17, a low-pass waveform, which is a determination waveform, is extracted from the tire acceleration waveform, which is a detected waveform, using the low-pass filter 14b having the cutoff frequency _fc set in step S16.
Then, from this low-pass waveform, the first acceleration information acquisition means 15 is used to calculate the RMS value S _a of the amplitude, which is a feature quantity for estimating the deterioration state of the bridge joint (step S18).
Finally, the deterioration state of the bridge joint is estimated from the RMS value S _a of the low-pass waveform obtained in step S18 and the threshold value K _V set in step S16 (step S19).
Specifically, when S _a ≧K _V , it is estimated that the reinforcing plate and rubber of the bridge joint 50 passed through are separated, and when S _a <K _V , the reinforcing plate and the rubber It is assumed that there is no peeling from the

[Experimental example]
A test course in which a large number of bridge joints A, in which the rubber and the top plate are not separated, and bridge joints B, in which the rubber and the top plate are separated, are randomly arranged. Running at 60 km/hr, the RMS value of the low-pass waveform S _a [a. u. ] are shown in FIG.
The center of the square in the figure is the median value m of the RMS value, and the upper and lower ends of the square are the quartiles.
As is clear from the table of FIG. 7, by comparing the RMS values S _a of the low-pass waveforms, it is possible to distinguish between the bridge joint A, in which the rubber and the top plate are not separated, and the bridge joint B, in which the rubber and the top plate are separated. confirmed that it can be done.

Although the present invention has been described above using the embodiments and experimental examples, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is also obvious to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the scope of the claims that forms with such modifications or improvements can also be included in the technical scope of the present invention.

For example, in the above-described embodiment, the cutoff frequency _fc and the threshold value _KV are set according to the vehicle speed. , the vehicle may be run at a constant speed (for example, 60 km/hr) when passing through the bridge joint to be measured. Thereby, the wheel speed sensor 12 and the cutoff frequency setting section 14a can be omitted.
In the above embodiment, the RMS value S _b of the amplitude of the unsprung acceleration waveform is used as the unsprung acceleration information for determining whether the bridge joint 50 has passed. The peak value may be compared with a preset peak value.
Further, instead of using the amplitude of the unsprung acceleration waveform, the similarity between the waveform shape of the measured unsprung acceleration waveform and a preset waveform shape may be compared. Note that the similarity comparison may use a mutual function, or may use well-known machine learning.
In the above-described embodiment, the RMS value S _a of the amplitude of the low-pass waveform was used as the tire acceleration information for determining whether the bridge joint 50 has been passed. Other acceleration information may be used, such as using a specific peak value among multiple peaks of the detected waveform or low-pass waveform, or a calculated value of multiple peak values.
Further, in the above-described embodiment, the acceleration sensor _mounted on the _tire 20 (the second 1 acceleration sensor 11) has passed through the bridge joint 50, but the amplitude of the tire acceleration waveform at the time _tb when the peak of the unsprung acceleration waveform is detected is greater than or equal to a preset threshold value. In some cases, it may be determined that the first acceleration sensor 11 has passed the bridge joint 50 .

10 bridge joint deterioration state estimation device, 11 first acceleration sensor,
12 wheel speed sensor, 13 second acceleration sensor, 14 determination waveform extraction means,
14a cutoff frequency setting unit, 14b low pass filter,
15 first acceleration information acquiring means, 16 threshold setting means,
17 second acceleration information acquisition means, 18 passage determination means,
19 joint deterioration state estimation means,
20 tires, 21 knuckles, 22 wheels, 23 axles, 24 hubs,
25 upper arm, 26 lower arm, 27 shock absorber.

Claims (6)

A method for estimating the state of deterioration of a bridge joint in which a reinforcing plate is arranged inside a rubber member, comprising:
A step of detecting a tire acceleration waveform, which is an acceleration waveform input from the road surface on which the bridge joint is installed, by a tire acceleration sensor, which is an acceleration sensor attached to a tire;
a step of acquiring tire acceleration information as a characteristic quantity of the tire acceleration waveform from the detected tire acceleration waveform;
The obtained tire acceleration information is compared with the tire acceleration information obtained when the tire acceleration sensor passes through the deteriorated bridge joint obtained in advance, and the deterioration state of the bridge joint is estimated from the result of the comparison. A deterioration state estimation method for a bridge joint, comprising the steps of: 2. A method for estimating a deteriorated state of a bridge joint according to claim 1, wherein said tire acceleration sensor is arranged on said tire so that the acceleration detection direction is in the tire circumferential direction. 3. A method for estimating a deterioration state of a bridge joint according to claim 1, wherein said tire acceleration information is a waveform obtained by passing said tire acceleration waveform through a low-pass filter. A step of detecting an unsprung acceleration waveform, which is a time-series waveform of acceleration input from the road surface on which the bridge joint is installed, by an unsprung acceleration sensor, which is an acceleration sensor installed on a non-rotating member under a vehicle spring;
a passage determination step of determining whether or not the tire acceleration sensor has passed the bridge joint from the detected unsprung acceleration waveform and the tire acceleration waveform;
In the step of estimating the state of deterioration of the bridge joint,
Only when it is determined in the passage determination step that the tire acceleration sensor has passed the bridge joint, the tire acceleration sensor passes through the acquired tire acceleration information and the deteriorated bridge joint determined in advance. 4. The deterioration state estimation method of a bridge joint according to any one of claims 1 to 3, wherein the deterioration state of the bridge joint is estimated by comparing the tire acceleration information when the tire acceleration is applied. In the passage determination step,
Determining whether the tire acceleration sensor has passed through the bridge joint from the time difference between the time when the peak of the unsprung acceleration waveform is detected and the time when the peak of the tire acceleration waveform is detected. The deterioration state estimation method of the bridge joint according to claim 4. A device for estimating the deterioration state of a bridge joint in which a reinforcing plate is arranged inside a rubber member,
a tire acceleration sensor that is mounted on a tire and detects a tire acceleration waveform that is an acceleration waveform input from the road surface on which the bridge joint is installed;
a tire acceleration information acquiring means for acquiring tire acceleration information as a characteristic quantity of the tire acceleration waveform from the detected tire acceleration waveform;
Deterioration state for estimating the deterioration state of the bridge joint by comparing the tire acceleration information with deterioration acceleration information that is acceleration information when the tire acceleration sensor passes the deteriorated bridge joint obtained in advance. an estimating means;
A degradation state estimation device for a bridge joint, comprising:

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