JP2020159150A - Track bed condition evaluation method - Google Patents

Abstract

To provide a track bed condition evaluation method that can quantitatively implement on-site evaluation of a condition of a track bed whose fine-grained fraction increased due to over-time deterioration without implementing a particle size testing.SOLUTION: A track bed condition evaluation method comprises: a tube placing process to place a test tube having an accelerometer into a track bed; an impact application process to apply an impact on a surface of the track bed; a measurement process to measure a load waveform due to the impact and an acceleration waveform in the track bed; an elastic wave velocity calculation process to calculate an elastic wave velocity from the load waveform and the acceleration waveform; a fine grain content ratio calculation process to obtain a fine grain content in the track bed from the elastic wave velocity; and a track bed soundness evaluation process to compare the fine grain content ratio with a predetermined threshold.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for evaluating a trackbed condition for evaluating the condition of the trackbed. In particular, the trackbed evaluates the condition of the trackbed by calculating the ratio of fine particles in the track bed from the elastic wave velocity by obtaining the elastic wave velocity. It relates to a state evaluation method.

The trackbed on which ballast or the like used for the track of a railroad vehicle is laid has a function of installing sleepers supporting the rail at a predetermined position and distributing the train load due to the repeatedly passing railroad vehicle to the roadbed.

Here, the ballast used for the trackbed is further refined by the repeated load of the railway vehicle and the compaction work by the maintenance machine. Here, fine granulation means that the particle size becomes less than 75 μm by scraping the ballast. It is known that the finely divided ballast impairs the above-mentioned train load distribution function because it becomes muddy by rainwater and solidifies when it dries. Therefore, it is necessary to diagnose the degree of deterioration of the ballast and carry out replacement work.

Various conventional methods for diagnosing the degree of deterioration of ballast are known. For example, as described in Patent Document 1, an elastic wave is propagated by striking a ballast, and the elastic wave propagating by this striking. The degree of deterioration of the track bed is diagnosed by measuring the wave as a response waveform and comparing the response waveform with preset comparison data.

According to such a roadbed condition evaluation method, it is possible to achieve high work efficiency and low cost without digging up the roadbed, and it is possible to realize labor saving and safety assurance of workers. Become.

Japanese Unexamined Patent Publication No. 11-37778

The trackbed condition evaluation method described in Patent Document 1 is different from the trackbed condition under the sleepers that supports the train load because the trackbed surface between the sleepers is generally replenished with new ballast. According to the measuring method described in Patent Document 1, there is a possibility that the state of the trackbed under the sleepers cannot be accurately measured.

In addition, the evaluation of the increase in fine particles due to aged deterioration of the trackbed is generally performed by conducting a particle size test, and there is also a problem that it is difficult to quantitatively perform it locally.

Therefore, the present invention has been made to solve the above problems, and the evaluation of the state where the track bed has deteriorated over time and the fine grain content has increased can be quantitatively evaluated in the field without conducting a particle size test. It is an object of the present invention to provide a method for evaluating a track bed condition that can be performed.

The roadbed condition evaluation method according to the present invention for solving the above problems includes a pipe body driving step of driving a test tube body equipped with an accelerometer into the trackbed, an impact applying step of applying an impact to the surface of the trackbed, and the impact. A measurement step of measuring the load waveform and the acceleration waveform in the track bed, an elastic wave velocity calculation step of calculating the elastic wave velocity from the load waveform and the acceleration waveform, and a fine particle content of the track bed from the elastic wave velocity. It is characterized by including a step of calculating the fine grain content to obtain the above, and a step of evaluating the soundness of the trackbed by comparing the fine grain content with a predetermined threshold value.

Further, in the roadbed condition evaluation method according to the present invention, the measurement step includes a time difference calculation step of obtaining a time difference of 10% of the peak of the load waveform and the acceleration waveform, and a loading position on which the impact is loaded. It is preferable to have a linear distance calculation step of obtaining the linear distance of the buried position of the accelerometer, and to obtain the elastic wave velocity from the time difference and the linear distance in the elastic wave velocity calculation step.

Further, in the roadbed condition evaluation method according to the present invention, the roadbed soundness evaluation step includes a determination step of determining that the roadbed is a target for roadbed replacement when the fine grain content is 8% or more. It is suitable.

According to the present invention, it is possible to quantitatively evaluate a state in which the track bed has increased fine particles due to aged deterioration without conducting a particle size test.

The flow chart of the roadbed state evaluation method which concerns on embodiment of this invention. The schematic diagram of the roadbed state evaluation method which concerns on embodiment of this invention. The schematic diagram of the test tube body used for the roadbed condition evaluation method which concerns on embodiment of this invention. Graph showing input response wave. A graph showing the relationship between elastic wave velocity and fine grain ratio. The graph which shows the relationship between the fine grain content of ballast and the displacement of sleepers.

An embodiment of the trackbed condition evaluation method of the present invention will be described with reference to the drawings.

FIG. 1 is a flow chart of a track bed condition evaluation method according to an embodiment of the present invention, FIG. 2 is a schematic diagram of a track bed condition evaluation method according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a schematic view of a test tube used in a method for evaluating a track bed condition according to a morphology, FIG. 4 is a graph showing an input response wave, and FIG. 5 is a graph showing a relationship between elastic wave velocity and fine particle ratio. FIG. 6 is a graph showing the relationship between the fine grain content of the ballast and the displacement of the sleepers.

As shown in FIG. 1, the trackbed condition evaluation method according to the present embodiment includes a digging step (S101) for digging up the trackbed and an accelerometer so that the surface of the trackbed and the bottom surface of the pillow are flush with each other. A tube driving step (S102) for driving a test tube into the track bed, an impact applying step (S103) for applying an impact to the surface of the track bed, and a measuring step (S104) for measuring the load waveform due to the impact and the acceleration waveform in the track bed. ), An elastic wave velocity calculation step (S105) for calculating the elastic wave velocity from the load waveform and the acceleration waveform, and a fine particle content rate calculation step (S106) for obtaining the fine particle content of the trackbed from the elastic wave velocity. It is provided with a roadbed soundness evaluation step (S107) for comparing the fine grain content with a predetermined threshold value.

In the digging step (S101), as shown in FIG. 2, the trackbed 10 is dug up so that the bottom surface of the sleepers 12 embedded and placed in the trackbed 10 and the trackbed surface 11 are flush with each other. l When an impact is applied to the trackbed surface by the impact applying step described later in this digging step (S101), the state of the fine particles under the trackbed can be accurately determined.

In the tube driving step (S102), the test tube body 20 including the accelerometer 21 is driven into the track bed 10. As shown in FIG. 3, the test tube body 20 includes a bottomed tubular tube body 22 having a predetermined length L and a housing body 23 attached to the bottom surface of the tube body 22, and the housing body 23 is provided. An accelerometer 21 is installed inside. Since the accelerometer 21 is attached to the upper surface of the housing 23, the linear distance h from the trackbed surface 11 to the accelerometer 21 can be known by measuring the length H of the pipe body 22 driven into the trackbed 10. Can be done.

In the impact applying step (S103), an impact is applied to the trackbed surface 11 by an impulse hammer 30 or the like. Furthermore, the measuring step (S104), as shown in FIG. 3, an impulse hammer 30, so through the analysis processor 31 is connected to the computer 32, measures the load waveform W _A 4 be able to. Further, accelerometer 21, because it is connected to the computer 32 in the same manner via the amplifier 33, it is possible to measure the acceleration waveform W _B as shown in FIG. As shown in FIG. 4, the load waveform W _A and the acceleration waveform W _B is calculated by the rise time determination step of determining the rise time t _A and t _B. The rise time t _A and t _B can be determined by various calculation methods. For example, it is preferable to define the position at which 10% of the peak values _VA and V _B of the first waveform are obtained as the rise time. Is. In the method for determining the roadbed condition according to the present embodiment, the rise time was determined by selecting a value of 10%, which is the minimum value, from 10 to 90% of the peak value, in accordance with JIS standard C0161.

Further, in the measurement step (S104), the test tube body 20 is driven into the track bed 10 in the time difference calculation step for obtaining the time difference ΔT of the rise time t _A and t _B described above and the tube body driving step (S102) described above. It has a linear distance calculation step of obtaining the linear distance h of the buried position of the accelerometer 21 from the track bed surface 11 on which the impact is loaded using the length.

In the elastic wave velocity calculation step (S105), the elastic wave velocity propagating in the track bed 10 is calculated from the above-mentioned time difference and the linear distance. Specifically, the elastic wave velocity ν can be calculated by ν = h / ΔT.

In the fine grain content calculation step (S106), the ratio of fine grains in the track bed 10 is calculated from the relationship with the elastic wave velocity ν. Specifically, the elastic wave velocity ν propagating the fine fraction content F _C and the track bed 10 of the track bed 10 is known that there is a linear relationship as shown in FIG. 5, according to the linear relationship, it is possible to calculate the fine fraction content F _C of the track bed 10 from the elastic wave velocity ν calculated in seismic velocity calculation step (S105). The linear relationship shown in FIG. 5 can be obtained from the test results conducted by changing the ratio of the fine particles in the track bed 10.

Ballast soundness evaluation step (S107) compares the fine fraction content was calculated by the fine fraction content rate calculating step (S106) F _C with a predetermined threshold value for evaluating the soundness of the track bed 10. Specifically, the fine fraction content F _C of the track bed 10, as shown in FIG. 6, the fine fraction content F _C in the track bed 10 is increased, the amount of displacement of the sleepers for loading number (subsidence amount) It has been confirmed by laboratory test that increases, this according to the laboratory test results, the amount of displacement of the sleepers the fine fraction content of F _C is greater than 8% can increase has been confirmed. Therefore, in the track bed state evaluation method according to the present embodiment, the determination that when the fine fraction content of F _C becomes 8% or more, track bed 10 that is the measurement object is the subject of the track bed exchange Judge by process.

As described above, according to the track bed condition evaluation method according to the present embodiment, the evaluation of the state in which the track bed 10 has deteriorated over time and the fine grain content has increased can be tested on-site without conducting a particle size test. By driving the pipe body 20 into the trackbed 10, it can be performed quantitatively, and the trackbed condition of the ballast under the sleepers, which is caused by the train load, can be independently evaluated, which affects the sinking of the trackbed. The condition of the track bed can be appropriately evaluated.

In the above-described embodiment, the rise time is defined as 10% of the peak value of the first waveform, and the elastic wave velocity is calculated. However, the rise time is not calculated from the peak value, and various calculation methods are used. It may be calculated by. It is clear from the description of the claims that the form with such changes or improvements may be included in the technical scope of the present invention.

10 Roadbed 11 Roadbed surface 12 Sleepers 20 Test tube 21 Accelerometer 22 Tube 23 Housing 30 Impulse hammer 31 Analytical processor 32 Computer 33 Amplifier L Tube length H Driving length h Straight distance

Claims (3)

The tube driving process of driving a test tube equipped with an accelerometer into the trackbed,
An impact applying process that applies an impact to the surface of the trackbed
A measurement process for measuring the load waveform due to the impact and the acceleration waveform in the track bed, and
An elastic wave velocity calculation step of calculating an elastic wave velocity from the load waveform and the acceleration waveform, and
A step of calculating the fine grain content of the track bed from the elastic wave velocity, and a step of calculating the fine grain content.
A method for evaluating a roadbed condition, which comprises a roadbed soundness evaluation step for comparing the fine grain content with a predetermined threshold value. In the roadbed condition evaluation method according to claim 1,
The measurement step includes a time difference calculation step for obtaining the difference in time that is 10% of the peak of the load waveform and the acceleration waveform, and a straight line for obtaining the linear distance between the loading position where the impact is loaded and the embedding position of the accelerometer. Has a distance calculation process
The elastic wave velocity calculation step is a method for evaluating a trackbed state, characterized in that the elastic wave velocity is obtained from the time difference and the linear distance. In the roadbed condition evaluation method according to claim 1 or 2,
The roadbed condition evaluation method is characterized by comprising a determination step of determining that the roadbed soundness evaluation step is a target of roadbed replacement when the fine grain content is 8% or more.

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