JP4220716B2 - Shock absorber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shock absorber connected to an entrance / exit of a tunnel structure, and more particularly, a shock absorber capable of eliminating or suppressing low-frequency air vibration generated by a pressure wave generated when a high-speed vehicle enters and exits the tunnel structure. About.
[0002]
[Prior art]
As shown in FIG. 8A, when the leading portion of the railway vehicle enters the tunnel, a compression wave is formed in the tunnel. This compression wave propagates through the tunnel at a speed of sound while increasing its pressure gradient, and is emitted as a pulsed pressure wave from this wellhead when it reaches the opposite wellhead (exit). This pressure wave is called a micro-pressure wave, and when it is radiated from a wellhead, it generates a “dawn” sound. Therefore, countermeasures have been studied as one of the environmental problems of high-speed railways. And since it became clear that the level of such a micro atmospheric pressure wave is almost proportional to the pressure gradient of the pressure wave which reached the tunnel exit, as one of the countermeasures for the micro atmospheric pressure wave, no sound is generated as a pressure wave on the tunnel exit side. In order to suppress the pressure gradient to a certain degree, that is, to reduce the pressure gradient formed at the tunnel entrance in advance.
[0003]
Specifically, as a countermeasure on the ground side, a tunnel buffer work consisting of a cover larger than the tunnel cross section is installed on the tunnel entrance side, side windows are formed on the side walls at regular intervals, and the opening amount of the side windows is further increased. Measures were taken, such as relieving the pressure gradient of the pressure wave formed at the tunnel entrance.
[0004]
With the installation of the tunnel buffer with such a configuration, a certain degree of achievement has been obtained with respect to the problem of reducing sound generated on the tunnel exit side by the micro-pressure wave.
[0005]
[Problems to be solved by the invention]
However, when the train enters the tunnel at high speed, not only the above-mentioned problem on the tunnel exit side due to the micro-pressure wave but also the so-called low frequency air vibration problem due to the rush wave (low frequency) generated on the tunnel entrance side. Arise.
[0006]
This low-frequency air vibration is caused by a pulsed pressure wave (inrush wave) generated when the high-speed railway moves from the light section (outside of the tunnel) to the tunnel section, such as when the cross section of the structure near the train changes. This is a vibration phenomenon that occurs when radiated from the tunnel entrance side to the surroundings. The problem of this low-frequency air vibration is particularly prominent in high-speed railways such as linear motor cars. When this low-frequency air vibration propagates along the railway, it causes rattling of the houses around the tunnel. As shown in FIG. 8B, this low frequency air vibration is also generated on the exit side of the tunnel due to a leaving wave (low frequency) generated when the train leaves the tunnel at a high speed.
[0007]
Therefore, conventionally, as a measure for reducing the low frequency, it has been performed to enlarge the buffer opening of the tunnel buffer or to adjust the opening amount of the side window of the tunnel buffer. Specifically, in order to alleviate the cross-sectional change between the tunnel buffer and the tunnel, the ceiling on the open side of the tunnel buffer (the side opposite to the connecting part with the tunnel) is cut into a V shape, The method of reducing the opening amount of the side window toward the tunnel wellhead was taken.
[0008]
However, even if such cutouts and side windows are provided, air vibrations occur due to a sudden pressure rise when the train passes through the end of such a V-shaped cutout or through the side windows. The above measures did not provide a fundamental solution.
SUMMARY OF THE INVENTION An object of the present invention is to provide a tunnel shock absorber that can eliminate or suppress low-frequency air vibrations that occur when a high-speed vehicle enters and exits a tunnel.
[0009]
[Means for Solving the Problems]
In view of the above problems, the shock absorber according to claim 1 is provided with a long cover having an open portion at one end and the other end connected to an entrance / exit of the tunnel structure, and a plurality of cover members on the wall surface of the cover And a pressure loss hole for adjusting the pressure loss of the pressure wave generated between the high speed vehicle and the cover to enter or exit the tunnel structure. A plurality of pressure loss holes are provided in the circumferential direction (that is, in a direction perpendicular to the longitudinal direction of the cover) in the vicinity of one end of the cover, and gradually decrease from one end to the other end of the cover. Further, the hole diameter or the hole width is such that the individual pressure loss coefficient at the pressure loss hole when the high-speed vehicle passes through the cover is substantially constant. 100mm or more and 300mm or less Is formed. The “tunnel structure” here includes not only a general tunnel but also a tunnel-like structure (hood-like structure) (hereinafter, simply referred to as “tunnel”).
[0010]
In addition, the “pressure loss hole” referred to here is a hole having a smaller opening amount than a side window generally found in the above-described prior art, and is an effective pressure loss of a pressure wave generated between the high-speed vehicle and the cover. Can be expected. In other words, with the conventional side window, this pressure wave will be released to the outside without giving much pressure loss, but in this shock absorber, the “pressure loss hole” with a certain pressure loss is compared. A large number of them are provided, each of which suppresses sudden fluctuations in pressure waves. A relatively large number of these “pressure loss holes” are provided in the circumferential direction (or width direction) in the vicinity of one end of the cover, and the number is gradually increased toward the other end along the longitudinal direction of the cover. It is decreasing.
[0011]
That is, for example, when a high-speed vehicle enters a tunnel, the pressure loss and the pressure gradient are substantially zero in front of the cover without a wall surface (light section), whereas the pressure loss is theoretical in the tunnel section with a wall surface. The pressure gradient becomes steep at the inlet. Therefore, in order to alleviate the change in the pressure gradient between the light section and the tunnel section, an intermediate state in which an appropriate pressure loss is imparted is formed by a tunnel buffer work provided with a plurality of pressure loss holes, and the high-speed vehicle gradually It creates the effect of entering or exiting a tunnel.
[0012]
In order to gradually change the intermediate state and smoothly connect the light section and the tunnel section, first, a relatively large number of pressure loss holes are arranged in the vicinity of the opening of the cover so that the pressure loss is relatively small. Then, a sharp rise of the pressure gradient of the pressure wave (rush wave) is suppressed. The pressure loss is gradually increased toward the tunnel entrance side to gradually increase the pressure loss, thereby preventing a sudden change in pressure gradient at the tunnel entrance. In other words, by gradually decreasing the pressure loss hole from the opening side of the cover toward the entrance of the tunnel, the pressure loss of the pressure wave generated between the high-speed vehicle and the cover is gradually increased, so that The pressure gradient changes smoothly.
[0013]
When the high-speed vehicle exits from the tunnel, the pressure loss holes gradually increase from the tunnel entrance toward the opening of the tunnel shock absorber, and the reverse effect is exerted between the high-speed vehicle and the cover. The pressure loss of the pressure wave generated between them will gradually decrease, but it is the same in that the change in the pressure gradient is smoothed.
[0014]
According to this configuration, it is possible to obtain the same effect as reducing the cross-sectional change of the structure when the high-speed vehicle enters or exits the tunnel. Generation of high frequency air vibration can be eliminated or suppressed. That is, it is possible to solve the problem of rattling of the furniture around the tunnel due to low-frequency air vibration that occurs when a high-speed vehicle enters or exits the tunnel at high speed.
[0015]
For example, as described in claim 2, when such a buffering work is configured as a tunnel buffering work for a high-speed railway, the effect is particularly remarkable. This is because a high-speed railway is particularly fast among high-speed vehicles traveling in a tunnel, and the higher the speed, the greater the pressure energy around the vehicle and the more likely it will be affected by low-frequency air vibrations around the tunnel entrance. In particular, this problem is considered to be prominent in a high-speed railway such as a linear motor car having a traveling speed of around 500 km / h. On the contrary, the effect of the present invention is particularly prominent.
[0016]
At that time, as described in claim 3, the opening ratio of the cover wall surface by the pressure loss hole is formed to be 10 to 20% at the outermost end near the one end, and gradually decreases toward the other end. The configuration is more effective. This is because the effect of suppressing low-frequency air vibrations is particularly effective when the aperture ratio is set, as will be described in the examples described later.
[0017]
According to a fourth aspect of the present invention, the pressure loss hole is preferably formed from the vicinity of one end of the cover to the vicinity of the other end. The experimental results revealed that the effect of reducing the sound generated on the tunnel exit side by the above-mentioned micro atmospheric pressure is increased by adopting a configuration that keeps the aperture ratio in the vicinity of the tunnel entrance / exit of the cover at a low rate. is there.
[0018]
According to such a configuration, the problem of low-frequency air vibration can be solved on one end side of the cover, and the problem due to the micro-pressure wave can be solved simultaneously on the other end side, and the pressure loss hole is directed to the other end side. Therefore, the effects of both can be continuously and smoothly exhibited.
[0019]
Specifically, the opening ratio of the portion of the cover from the tunnel entrance (for example, the portion from the center of the cover to the vicinity of the tunnel entrance) is maintained at about 1% (preferably 0.8% to 0.9%). As a result, it has been found from experimental results that the effect of reducing the sound generated by the micro-pressure wave at the tunnel exit side is increased.
[0020]
Further, in order to obtain an effective pressure loss at each pressure loss hole, the Reynolds number of the airflow passing through the pressure loss hole needs to be a certain value (1000 or more). Experimental results have also been obtained in which the pressure loss coefficient becomes constant when the Reynolds number exceeds a certain value.
For this reason, the claims 1 As described in the above, the pressure loss hole is preferably formed so that the hole diameter or hole width is such that the individual pressure loss coefficient in each pressure loss hole when the high-speed vehicle passes through the cover is substantially constant. .
[0021]
However, if the pressure loss hole is too large, there is a concern that the pressure wave radiated from the pressure loss hole will increase. For example, in the case of high-speed railway, the diameter or width of the pressure loss hole is the average cross-sectional scale of the vehicle. It is desirable to be about 1/10 or less of the above.
In consideration of such circumstances, the shock absorber for high-speed rails is preferably formed so that the hole diameter or hole width of the pressure loss hole is about 10 mm or more and 1000 mm or less.
[0022]
This is because it is considered sufficient if the hole diameter or the hole width of the pressure loss hole is about 10 mm in order to secure the Reynolds number for the high-speed railway shock absorber. Further, the preferable pressure loss is almost determined by the ratio between the thickness of the cover wall and the size of the pressure loss hole (hole diameter or hole width). When the hole diameter or hole width is smaller than 10 mm, the wall of the cover This is because the thickness of the cover must be reduced, and in this case, the strength of the cover cannot sufficiently withstand the fluctuating pressure when the vehicle passes. In addition, when the hole diameter or the hole width is small, so-called whistle noise is likely to be generated, which causes a problem of noise. On the other hand, if it is larger than 1000 mm, the pressure wave radiated from the pressure loss hole is increased.
[0023]
However, if the hole diameter or the hole width is small, it is necessary to form a larger number of pressure loss holes, and there is a problem that the processing cost of the buffering work increases. Conversely, when the hole diameter or hole width is large, particularly when the pressure drop hole is provided on the upper wall of the cover, throwing an object into the pressure drop hole, a fall accident of an operator working on the cover, etc. There is also concern that this problem will occur. For this reason, it is more preferable that the hole diameter or the hole width is about 100 mm or more and 300 mm or less.
[0024]
Further, it has been found that the whistle noise of the pressure loss hole is greatly influenced by the shape of the peripheral edge. In particular, when the cover is made of a steel plate or the like, it may occur due to burrs remaining during pressure loss hole processing.
Therefore, as described in claim 6, it is preferable that the peripheral edge of the pressure loss hole is chamfered because such a problem can be avoided.
[0025]
The shock absorber according to claim 7 includes an enclosure wall connected to one end of the cover, and the enclosure wall is formed so that the side wall gradually increases from the road surface toward one end of the cover. Yes. Although the technique itself for providing such an enclosure wall is already a known technique, a remarkable effect that has not been achieved in the past can be exhibited by combining with the above-described configuration of the present invention.
[0026]
That is, in such a configuration, for example, when the railway vehicle is about to enter the tunnel, the pressure wall pressure gradient between the railway vehicle and the enclosure wall can be gradually increased by gradually increasing the enclosure wall. it can. When the railway vehicle reaches the cover, it is possible to reach the tunnel section while giving a suitable pressure loss by the pressure loss hole and smoothly increasing the pressure gradient of the pressure wave. As a result, the change in the pressure gradient between the light section and the tunnel section can be further alleviated, and the low frequency air vibration can be more effectively eliminated or suppressed.
[0027]
However, if the pressure drop holes are also distributed on the side wall of the cover at that time, the pressure drop holes will suddenly appear in the enclosure wall where no holes are provided, and the pressure distribution due to the pressure wave is disturbed. There is a risk of causing noise and vibration.
Therefore, in the case of providing an enclosure wall without a hole, the claim 7 As described in only It is good to be provided.
[0028]
According to such a configuration, the space above the enclosure wall is gradually narrowed toward the cover. Therefore, by providing the pressure loss hole on the upper wall, the space is continuously reduced. It is possible to create various situations and to connect aerodynamically very smoothly. As a result, the occurrence of low frequency air vibration can be more effectively eliminated or suppressed.
[0029]
Further, by providing the pressure loss hole on the upper wall, even if some air vibration remains, the air vibration can be reduced by the diffraction effect, and further, the running sound of the high-speed vehicle can be reduced.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the shock absorber according to the present invention is constructed as a tunnel shock absorber of a high-speed railway, and FIG. 1 is a perspective view showing a schematic configuration of the tunnel shock absorber.
[0031]
As shown in FIG. 1, the tunnel buffer 1 is composed of a long cover 10 having a total length of about 100 m, a width of about 14 m, and a height of about 7 m, one end of which forms an open portion 10a, and the other end is a tunnel T. It is connected to the doorway.
As shown in the plan view of the tunnel shock absorber 1 in FIG. 2 (a), the cover 10 is composed of a plurality of steel plates 21 in a rectangular frame structure formed by connecting a plurality of H-shaped steels (not shown) in a lattice shape. A PC board (pre-stressed concrete board) 22 is provided and configured.
[0032]
The steel plate 21 has a rectangular main body having a length L1 of about 2 m, a width W1 of about 1 m, and a thickness t1 of about 9 mm, as shown in FIG. The pressure loss hole 30 is provided. The pressure loss hole 30 is a pressure suitable for a pressure wave generated between the cover 10 and a high-speed railway vehicle (in this embodiment, a linear motor car: not shown) that enters or exits the tunnel T. It is a hole for imparting a loss. In this embodiment, the pressure loss hole 30 is formed as a circular hole having a diameter of 100 mm, and a chamfer (not shown) for preventing a so-called whistle noise is applied to the peripheral edge.
[0033]
However, there are a plurality of types of steel plates 21 having different numbers of pressure loss holes 30 for the convenience of setting the aperture ratio described later (maximum 32 in this embodiment, minimum 2).
On the other hand, the PC board 22 has a rectangular main body having a length L2 of about 2 m, a width W2 of about 1 m, and a thickness t2 of about 70 mm, as shown in FIG.
[0034]
And as shown to the figure (a), the upper wall 11 of the cover 10 arrange | positions these steel plates 21 (scattered pattern in a figure) and PC board 22 (no pattern in a figure) in a fixed form without multiple gaps. Thus, the both side walls 12 of the cover 10 are configured such that only the PC plates 22 are arranged without a plurality of gaps. Therefore, in this embodiment, only the upper wall 11 of the tunnel buffer 1 has a porous structure. Further, the steel plate 21 and the PC plate 22 are selectively arranged so that the pressure loss holes 30 gradually decrease from the open portion 10a side of the cover 10 toward the entrance / exit of the tunnel T.
[0035]
In the present embodiment, the constant region (approximately 14 m) at the end of the tunnel buffer 1 on the tunnel entrance side is a step elimination zone, and the pressure loss hole 30 is not disposed.
Next, the evaluation about the arrangement | positioning aspect of the pressure loss hole provided in a cover is demonstrated. That is, the inventors have verified the arrangement of pressure loss holes suitable for countermeasures against low-frequency air vibration that occurs when a high-speed vehicle enters and exits a tunnel by numerical analysis and model experiment. Hereinafter, these results will be described.
[Numerical analysis results]
First, a plurality of holes (pressure loss holes) are provided on the cover wall surface of the tunnel shock absorber, and the holes are gradually reduced from one end side (buffer opening: opening side) of the cover toward the other end side (tunnel entrance / exit side). Assuming that, the numerical analysis was performed on the relationship between the distribution of the opening ratio of the cover wall of the tunnel buffer and the effect of reducing the pressure wave.
[0036]
Specifically, as a tunnel buffer having an opening ratio distribution in which the opening ratio of the cover gradually decreases, a plurality of patterns having different opening ratios at the extreme end near the buffer opening are set, and a high-speed railway vehicle is set for each of them. The pressure fluctuation of the rush wave (pressure wave) when rushing was analyzed. FIG. 3 is an explanatory diagram showing the analysis conditions of the numerical analysis, and FIG. 4 is a graph showing the analysis results.
[0037]
As shown in the conceptual diagram of the high-speed railway vehicle as viewed from the top in FIG. 3, in this numerical analysis, the eccentric running of the high-speed railway vehicle is simulated, the tunnel diameter is D, and the total length of the tunnel buffer is L (= 25 0.0D), the evaluation point of the air vibration was set at a position of 5.0D from the high-speed railcar running eccentrically at the buffer entrance. Moreover, the traveling speed of the high-speed railway vehicle was set to 500 km / h. And the length of the porous wall which arrange | positions a pressure loss hole was set to Lp (= L / 2 = 12.5D) from the buffer entrance, and four types with different opening ratio distribution were set as this porous wall.
[0038]
That is, as shown in the lower graph of FIG. 3, a porous wall (1) (thick solid line) with an opening ratio β of 14.1% in the vicinity of the buffer work entrance, as shown in a graph showing the relationship of the opening ratio distribution with respect to the distance from the buffer work entrance, Numerical analysis was performed on 28.2% porous wall (2) (dashed line), 42.3% porous wall (3) (dotted line), and 7.05% porous wall (4) (dotted line). The horizontal axis of the graph represents a dimensionless distance in which the distance X from the buffer entrance is expressed as a ratio to the length Lp of the porous wall, and the vertical axis represents the aperture ratio at the dimensionless distance. Each of these porous walls is set so that the opening ratio gradually decreases from the buffer entrance to the tunnel pit (entrance / exit), and is opened at the center of the tunnel buffer (X = Lp = 1 / 2L). The rate is set to zero.
[0039]
FIG. 4 represents time-series data of pressure wave pressure fluctuations when it is assumed that the high-speed railcar is running 0.2D eccentrically (running a position 0.2D from the center of the tunnel shock absorber). . As described above, the evaluation point is a position 5.0D from the high-speed railway vehicle at the buffer work entrance position (X = 0.0D). The horizontal axis represents the measurement time (s) where the time when the tip of the high-speed railway vehicle passes through the buffer entrance is 0.0 (s), and the vertical axis represents the pressure fluctuation at the measurement time. In addition to the above-described porous walls (1) to (4), this analysis was also performed for a comparative example in which no pressure loss hole was provided (no opening: thin solid line). There is a negative value for time (s), which means that the high-speed railcar is analyzing pressure fluctuations before entering the tunnel buffer.
[0040]
As can be seen from the figure, in each case, first, there is a negative pressure peak value near time 0.1 (s) and a positive pressure peak value near time 0.5 (s). Since these peak values (amplitudes) mean the magnitude (intensity) of the pressure wave, focusing on the peak values, the porous wall {circle around (1)} (β = 14.1), porous Wall (2) (β = 28.2), porous wall (3) (β = 42.3), porous wall (4) (β = 7.05), no opening (β = 0.0) ing. Therefore, it was found that the pressure reduction effect was most obtained when the opening ratio in the vicinity of the buffer entrance was 10 to 20%.
[Model experiment results]
Subsequently, a model experiment was conducted based on the results of the numerical analysis. The upper part of FIG. 5 is a plan view showing a tunnel buffer model M, the right part shows a cross-sectional view thereof, and the lower part shows a side view thereof.
[0041]
This model M is an approximately 1/34 model of the actual tunnel buffer 1 and was made by processing a steel plate. The total length L of the cover M1 of the model M is 2941 mm, and the length Lp from the buffer work entrance of the porous wall portion in which the pressure loss hole (shown by a dot in the figure) is arranged is 1470 mm (= 1/2 L). It is formed to become. The cross section is larger than the cross section of the tunnel model t (diameter D), and the width W is 440 mm and the height H is 220 mm. The track R is eccentrically laid on the left and right sides from the tunnel buffer to the tunnel t, and a high-speed railway model (not shown) can be run along the track R.
[0042]
A large number of pressure loss holes formed in a circular hole having a diameter of 10 mm were provided. The arrangement is as shown in the figure, and is set so that the number gradually decreases from one end side to the other end side of the tunnel buffer. Specifically, based on the numerical analysis results described above, the analysis result was the best with an opening ratio near the buffer entrance of 14%, and a comparative example with an opening ratio of 45%. A model experiment was conducted with a zero rate (fully closed). In addition, in this model experiment, as shown in FIG. 6, a test was also conducted on a tunnel buffer work in which a pair of triangular walls S (enclosure walls) were connected to one end of a cover M1 having an aperture ratio of 14%. The triangular wall S is obtained by processing a steel plate into a right triangle having an elevation angle θ (15 degrees in this embodiment), and is formed so that its height matches the height H of the cover M1. That is, the triangular wall S is formed so as to gradually increase from the road surface toward one end of the cover M1.
[0043]
In the model experiment, a high-speed railway model was run along the track R at about 500 km / h and passed through the model M and the tunnel model t. The pressure measurement point (evaluation point) was a position at a distance 5.0D (D: diameter of tunnel t) from the center of the line R at the buffer entrance. The result is shown in FIG. FIG. 4A shows the experimental result of full closure (opening ratio zero), and FIG. 4B shows the experimental result of 45% opening ratio in the vicinity of the buffer entrance. Further, FIG. 4C shows the experimental result with an aperture ratio of 14%, and FIG. 4D shows the experimental result with the triangular wall S further installed for an aperture ratio of 14%. ing. In each figure, the horizontal axis represents the measurement time (s), and the vertical axis represents the pressure fluctuation at the measurement time.
[0044]
As can be seen from FIG. 7, the peak value (edge portion) of the pressure appears greatly around the time 0.42 (s) and the time 0.43 (s) for the fully closed one. On the other hand, for the aperture ratio of 45%, the amplitude of the corresponding peak value is somewhat smaller. Then, when the aperture ratio becomes 14%, the amplitude of the peak value becomes smaller, and it is understood that the amplitude of the peak value almost disappears in the case where the triangular wall S is provided. In addition, these graphs are the results of measurement in which the pressure energy (pressure field) in the vicinity of the vehicle generated when the vehicle travels at high speed overlaps with the air vibration generated from the buffer. Pressure energy (pressure field) is a phenomenon that occurs due to factors such as travel speed and vehicle cross-sectional area, and cannot be completely suppressed by a tunnel buffer. In FIG. 7 (d), the air vibration is greatly reduced and has a waveform close to a pressure change due to pressure energy (pressure field).
[0045]
That is, since the low frequency air vibration is caused by the magnitude of the peak value (that is, the pressure wave), the problem of the low frequency air vibration is greatly increased by setting the aperture ratio to 14% and providing the triangular wall S. It turns out that it is suppressed.
Returning to FIG. 2, based on the numerical analysis result and the model experiment result as described above, in the tunnel buffer 1 of the present embodiment, the opening ratio at the end portion near one end of the cover 10 becomes 10 to 20%. Thus, the steel plate 21 (that is, the pressure loss hole 30) is provided, and is configured to gradually decrease toward the other end.
[0046]
As described above, according to the tunnel buffer 1 of the present embodiment, the pressure loss of the pressure wave generated between the high-speed railway vehicle entering the tunnel T or leaving the tunnel T and the cover 10 is reduced. A plurality of pressure loss holes 30 to be adjusted are provided, and the pressure loss holes 30 are arranged so as to gradually decrease from one end side to the other end side of the cover 10.
[0047]
For this reason, it is possible to form an intermediate state in which moderate pressure loss is imparted between the light section and the tunnel section, and to create an effect as if the high-speed railway vehicle gradually enters the tunnel T. Can do. That is, it is possible to suppress a sharp rise in the pressure gradient of the pressure wave (rush wave) and smooth the change in the pressure gradient. As a result, it is possible to eliminate or suppress the occurrence of low-frequency air vibration due to the rush wave of the high-speed railway vehicle, and to solve the rattling problem of the furniture around the tunnel.
[0048]
In the above embodiment, the case where the high-speed railway vehicle enters the tunnel T has been described as an example. However, the same effect can be obtained when the vehicle exits the tunnel T. That is, according to the configuration of the above-described embodiment, the pressure loss holes 30 gradually increase from the tunnel entrance toward the open portion 10a of the tunnel shock absorber 1, and the reverse operation is achieved. The pressure loss of the pressure wave generated between the pressure wave 10 and the pressure wave 10 gradually decreases, but the same is true in that the change in the pressure gradient is smoothed.
[0049]
Therefore, even when the high-speed railway vehicle leaves the tunnel T, the occurrence of low-frequency air vibration due to the leaving wave can be eliminated or suppressed, and as a result, the problem of rattling of the furniture around the tunnel can be solved. Can do.
As mentioned above, although the Example of this invention was described, it cannot be overemphasized that embodiment of this invention can take various forms, as long as it belongs to the technical scope of this invention, without being limited to the said Example at all. Nor.
[0050]
For example, in the said Example, although the thing of the cross-section rectangular frame shape comprised using many rectangular steel plates 21 and PC boards 20 was shown as the cover body 10 of the tunnel shock absorber 1, a cover body becomes this shape. For example, it may be formed in a semicircular cross section. Further, without using a large number of steel plates or PC plates, for example, a cover can be constructed from reinforced concrete, and then pressure loss holes can be drilled at predetermined locations. Furthermore, although the example which formed the pressure loss hole 30 which is a circular hole with respect to the steel plate 21 was shown, the pressure loss hole can also be formed in other shapes, such as a square hole.
[0051]
In the above embodiment shown in FIG. 2, the enclosure wall (corresponding to the triangular wall S) was not touched, but the effect of reducing the pressure wave appears well as seen from the model experiment. It is preferable that a triangular wall is provided. In the model experiment, a configuration in which the triangular wall S having an elevation angle θ of 15 degrees is provided as the enclosure wall is shown. However, if the elevation angle θ is 30 degrees or less (preferably 15 degrees or less), a good effect is obtained. Is known from another experiment.
[0052]
Furthermore, in the above-described embodiment, the tunnel buffer for high-speed railway has been described, but it is needless to say that it may be constructed for high-speed vehicles other than railway vehicles.
In addition, it is possible to envisage the installation of tunnel-like structures (hoods) on light structures (such as viaducts) as noise countermeasures for densely populated areas and snow countermeasures in heavy snow areas. In this case, there is actually no tunnel, but the situation is similar to the existence of a tunnel wellhead. Naturally, also in this case, it is possible to apply a shock absorber using a perforated plate (that is, a shock absorber using a perforated plate (steel plate 21 in the above embodiment) is not applicable only to a tunnel, and has the same aspect. The performance equivalent to the content of the present invention is exhibited by installing it at a location where
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of a shock absorber according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating a configuration of a tunnel buffer according to an embodiment.
FIG. 3 is an explanatory diagram showing analysis conditions for numerical analysis performed to construct the tunnel buffer work of the example.
4 is a graph showing the results of numerical analysis in FIG.
FIG. 5 is an explanatory diagram of a model according to a model experiment conducted for constructing the tunnel buffer work of the example.
FIG. 6 is an explanatory diagram of a model according to a model experiment performed for constructing the tunnel buffer work of the example.
FIG. 7 is a graph showing the results of a model experiment.
FIG. 8 is an explanatory diagram showing a problem of the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Tunnel shock absorber, 10 ... Cover, 21 ... Steel plate,
22 ... PC board, 30 ... pressure loss hole

Claims (7)

An elongate cover having an open portion at one end and the other end connected to the entrance / exit of the tunnel structure;
A plurality of pressure reduction holes provided on the wall surface of the cover, for adjusting pressure loss of pressure waves generated between the high speed vehicle entering the tunnel structure or leaving the tunnel structure and the cover; and
A shock absorber with
A plurality of the pressure loss holes are provided in the circumferential direction in the vicinity of one end side of the cover, and are disposed so as to gradually decrease from one end side to the other end side of the cover, and further, the hole diameter or the hole width thereof However, the shock absorber is characterized in that it is formed in a size of 100 mm or more and 300 mm or less , which is a size in which each pressure loss coefficient in the pressure loss hole when the high speed vehicle passes through the cover is substantially constant.   The shock absorber according to claim 1, wherein the shock absorber is configured as a tunnel shock absorber for a high-speed railway.   The shock absorber according to claim 1 or 2, wherein an opening ratio of the wall surface of the cover by the pressure loss hole is 10 to 20% at an outermost end portion near the one end. .   The shock absorber according to any one of claims 1 to 3, wherein the pressure loss hole is formed from the vicinity of one end of the cover to the vicinity of the other end.   The shock absorber according to any one of claims 1 to 4, wherein the peripheral edge of the pressure loss hole is chamfered. In the shock absorber according to any one of claims 1 to 5,
An enclosure wall connected to one end of the cover;
The buffer wall is characterized in that the side wall is formed so that the side wall gradually increases from the road surface toward one end of the cover.   The shock absorber according to any one of claims 1 to 6, wherein the pressure loss hole is provided only on an upper wall of the cover.

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