JP6635836B2 - Pressure fluctuation reduction structure - Google Patents

Description

  The present invention relates to a pressure fluctuation reducing structure provided in a tunnel including a tunnel main shaft through which a vehicle passes and an inclined shaft communicating the tunnel main shaft with the outside.

  In a tunnel through which a vehicle such as a railway vehicle passes, a plurality of vertical shafts and diagonally extending shafts are provided branching from the main tunnel in order to secure ventilation and an evacuation route in the tunnel. However, low-frequency pressure fluctuations generated in the tunnel when vehicles pass through the tunnel and the blasting sound of tunnel excavation work are propagated through tunnel main shafts, vertical shafts and inclined shafts and released to the surface, and low-frequency air There is a problem that the vibration is caused and affects the surrounding environment.

  Therefore, Patent Literature 1 discloses a shaft structure provided in a shaft or an inclined shaft to reduce pressure fluctuations generated when a railway vehicle passes through a tunnel. In this shaft structure, an air chamber is formed so as to intersect the longitudinal direction of the shaft, and the air chamber is separated into a plurality of spaces by one or a plurality of perforated plates. According to such a configuration, the pressure fluctuation passing through the hole of the perforated plate has a damping effect due to viscosity or pressure loss, and the pressure fluctuation is converted into thermal energy, so that the pressure fluctuation is reduced. This shaft structure has a high sound absorption coefficient against pressure fluctuations of low frequency of 20 Hz or less.

JP 2008-215019 A

  However, the cross section of the inclined shaft provided from the mountain tunnel is smaller than that of the vertical shaft provided by branching from the deep underground tunnel having a depth of about 40 m. Therefore, when the vertical shaft structure of Patent Literature 1 is applied to an inclined shaft, there is a problem that it is difficult to secure an installation space in a direction orthogonal to the longitudinal direction of the inclined shaft.

  Further, the shaft structure of Patent Literature 1 is provided in a framework structure built in the shaft along the longitudinal direction of the shaft. Accordingly, when the shaft structure of Patent Document 1 is provided in the inclined shaft, it is necessary to similarly construct a frame structure in the inclined shaft. However, as described above, the cross-section of the shaft is smaller than that of the shaft, and the installation space in the direction orthogonal to the longitudinal direction of the shaft is small. Therefore, in order to ensure sufficient sound absorption performance, it is necessary to provide the shaft structure of Patent Document 1 over a long range in the longitudinal direction. Then, the construction distance of the frame structure becomes long, and the construction cost increases.

  Further, the space formed between the shaft structure of Patent Document 1 and the wall surface of the shaft is a wasteful space, and is inefficient in effectively utilizing the cross-sectional area of the shaft. Further, in the pressure fluctuation reduction structure using a perforated plate as in the shaft structure of Patent Document 1, the size of the air layer behind leads to the sound absorbing performance. Therefore, the space that does not contribute to the sound absorbing performance is provided by the pressure fluctuation. It is inefficient in taking measures.

  Further, there is a problem that noise such as blasting noise in tunnel construction propagates through the main tunnel, the vertical shaft, and the inclined shaft, and is released to the surrounding environment. Therefore, it is conceivable to provide a silencer inside to reduce noise emitted to the surrounding environment. However, since the noise that can be reduced by the silencer is a component of 200 Hz or higher, a low frequency component of approximately 160 Hz or lower is directly emitted to the surrounding environment. As described above, the shaft structure of Patent Document 1 is sufficiently effective for low-frequency pressure fluctuations of 20 Hz or less, but is expected to be effective for low-frequency noise of more than 20 Hz and 160 Hz or less. Absent.

  An object of the present invention is to provide a pressure fluctuation reducing structure capable of reducing low-frequency pressure fluctuation and low-frequency noise by effectively utilizing the cross-sectional area of a tunnel while suppressing construction costs.

  The present invention is a pressure fluctuation reducing structure provided in a tunnel including a tunnel main shaft through which a vehicle passes, and an inclined shaft communicating the tunnel main shaft with the outside, and at least one of two side surfaces of the tunnel. A first partition plate disposed at a predetermined interval between the side surface and the side surface, and provided on at least one of two wall surfaces forming a ceiling and a floor of the gallery, A second partition plate disposed opposite to the wall surface at a predetermined interval, and at least one of the first partition plate and the second partition plate has a large number of through holes. The inner space of the tunnel is partitioned into an air passage and a back air layer by the first partition plate and the second partition plate.

  According to the present invention, the inner space of the tunnel is partitioned into the air passage and the back air layer by the first partition plate and the second partition plate. The side walls and upper and lower wall surfaces of the tunnel (hereinafter, these are referred to as wall surfaces) serve as substitutes for the back plate in the pressure fluctuation reduction structure using the perforated plate, so that the first partition plate and the second partition plate and the The air layer and the wall of the tunnel form a pressure fluctuation reduction structure using a perforated plate. Therefore, when low-frequency pressure fluctuation or low-frequency noise passing through the air passage passes through the through-hole of the porous portion, damping action occurs due to viscosity or pressure loss. Due to this damping action, low-frequency pressure fluctuations and low-frequency noise are converted into thermal energy, so that low-frequency pressure fluctuations and low-frequency noise are attenuated. Thus, low-frequency pressure fluctuation and low-frequency noise can be reduced.

  As described above, by replacing the wall surface of the tunnel with the back plate, it is only necessary to install the first partition plate and the second partition plate in the tunnel, so that the installation cost can be reduced. Since the pressure fluctuation reducing structure using a perforated plate is sealed by the back plate, it receives the pressure of the pressure fluctuation passing through the air passage. Therefore, it is necessary to design the strength of the frame structure in accordance with this. However, in this structure, since only the first partition plate and the second partition plate are provided, the pressure received is small. Further, this structure is lighter than the pressure fluctuation reducing structure using a perforated plate. Therefore, the frame structure can be simplified. Thereby, the construction cost can be reduced. In addition, since the space between the first partition plate and the second partition plate and the wall surface of the tunnel is all behind the air layer, there is no wasteful space between the wall and the wall surface of the tunnel. Therefore, the sectional area of the tunnel can be effectively used.

  Therefore, it is possible to reduce the low-frequency pressure fluctuation and the low-frequency noise by suppressing the construction cost and effectively utilizing the cross-sectional area of the tunnel.

It is a perspective view of a shaft. It is AA sectional drawing of FIG. It is sectional drawing of a shaft. FIG. 2 is a cross-sectional view of the inclined shaft when FIG. 1 is viewed from a direction B. It is a schematic diagram of the pressure fluctuation reduction structure of the present embodiment. It is a schematic diagram of the pressure fluctuation reduction structure of the present embodiment. It is a schematic diagram of the conventional pressure fluctuation reduction structure. It is a figure which shows the relationship between the relative pressure gradient value of the pressure fluctuation | variation in a tunnel, and the relative pressure in the pit of an inclined shaft. It is a perspective view of a shaft. It is a figure which shows the relationship between the relative pressure gradient value of the pressure fluctuation | variation in a tunnel, and the relative pressure in the pit of an inclined shaft.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Structure of the shaft)
As shown in FIG. 1 which is a perspective view, the pressure fluctuation reducing structure 1 according to the embodiment of the present invention is provided in an inclined shaft 23 which connects a tunnel main shaft 21 through which a vehicle passes with the outside 22. Here, the tunnel main shaft 21 is a mountain tunnel provided in a mountain or the like. The inclined shaft 23 extends obliquely and connects the outside 22 which is a mountain surface to the main tunnel 21. The vehicle is a vehicle such as a railway vehicle or an automobile. The pressure fluctuation reduction structure 1 may be provided in the main tunnel 21.

  In the shaft 23, a plurality of wide sections 23a wider than other sections are provided in the longitudinal direction of the shaft 23. The wide section 23a is an evacuation site at the time of the construction of the shaft 23, and is a section having a larger cross-sectional area in a direction orthogonal to the longitudinal direction of the shaft 23 than other sections.

  As shown in FIG. 2 which is an AA cross-sectional view of FIG. 1, the internal space of the shaft 23 (wide section 23a) is formed by left and right side surfaces 231 and 23r, a ceiling surface 23u, and a floor surface 23d. . A construction vehicle 31 such as a truck runs on the floor surface 23 d of the shaft 23.

  Note that a ventilation fan (not shown) for forcibly ventilating the inside of the shaft 23 may be provided in the shaft 23. Noise is generated from the ventilation fan, propagates through the shaft 23 and leaks to the outside 22. Therefore, a silencer (not shown) that reduces noise emitted to the outside 22 may be provided in the inclined shaft 23.

(Structure of shaft)
Here, in order to explain the prior art, a sectional view of the shaft 43 is shown in FIG. The shaft 43 extends vertically and connects the tunnel main shaft 41 through which the vehicle 61 passes with the outside 42.

  When the shaft structure 51 of Patent Literature 1 is provided in the shaft 43, a frame structure 44 in which steel frames are vertically and horizontally assembled is constructed in the shaft 43. Then, the shaft structure 51 of Patent Document 1 is provided in the frame structure 44.

  However, the shaft 23 shown in FIG. 2 has a smaller cross-sectional area than the shaft 43 shown in FIG. Therefore, when the shaft structure 51 of Patent Document 1 is applied to the shaft 23, there is a problem that it is difficult to secure an installation space in a direction orthogonal to the longitudinal direction of the shaft 23.

  When the shaft 51 of Patent Document 1 is provided in the shaft 23, it is necessary to construct the frame structure 44 in the shaft 23 in the same manner as in the shaft 43. However, since the installation space in the direction perpendicular to the longitudinal direction of the shaft 23 is small, it is necessary to provide the shaft structure 51 of Patent Document 1 over a long range in the longitudinal direction in order to ensure sufficient sound absorbing performance. Then, the construction distance of the frame structure 44 becomes long, and the construction cost increases.

  Further, as shown in FIG. 3, when the shaft 51 of Patent Document 1 is provided in the shaft 43, the frame structure 44, that is, the space between the shaft structure 51 of Patent Document 1 and the wall surface of the shaft 43 is wasteful. A certain space 45 is formed. When the shaft structure 51 of Patent Document 1 is applied to the shaft 23, a similar space is formed between the shaft structure 51 of Patent Document 1 and the wall surface of the shaft 23. However, this space is wasted space, and efficiency is low in effectively utilizing the cross-sectional area of the shaft 23. Further, in the pressure fluctuation reduction structure using a perforated plate, such as the shaft structure 51 of Patent Document 1, the size of the air layer behind leads to the sound absorbing performance. It is also inefficient in dealing with fluctuations.

  Further, there is a problem that noise such as a blasting sound in tunnel construction propagates through the shaft 23 and is released to the outside 22. The shaft structure 51 of Patent Document 1 is sufficiently effective for low-frequency pressure fluctuations of 20 Hz or less, but cannot be expected for low-frequency noise of more than 20 Hz and 160 Hz or less.

(Configuration of pressure fluctuation reduction structure)
As shown in FIG. 2, the pressure fluctuation reduction structure 1 of the present embodiment is provided in a wide section 23 a of a shaft 23.

  The pressure fluctuation reduction structure 1 has a first partition plate 2 disposed opposite to the side surface 231 at a predetermined interval from the left side surface 231 of the inclined shaft 23 in the figure. The first partition plate 2 is arranged in the up-down direction, the lower end is connected to the floor surface 23d of the shaft 23, and the upper end is located below the ceiling surface 23u of the shaft 23. In the present embodiment, the first partition plate 2 is a perforated plate having a large number of through holes on the entire surface. However, the first partition plate 2 may have a configuration in which a porous portion having a large number of through holes is partially provided.

  In addition, the pressure fluctuation reducing structure 1 has a second partition plate 3 disposed opposite to the ceiling surface 23u at a predetermined interval from the ceiling surface 23u of the inclined shaft 23. The second partition plate 3 is arranged in the left-right direction, the right end is connected to the right side surface 23r of the shaft 23 in the figure, and the left end is located to the right of the left side surface 23l of the shaft 23 in the diagram. are doing. In the present embodiment, the second partition plate 3 is a perforated plate having a large number of through holes on the entire surface. However, the second partition plate 3 may be configured to partially include a porous portion having a large number of through holes.

  The upper end of the first partition plate 2 and the left end of the second partition plate 3 are connected. Thus, the internal space of the wide section 23 a is partitioned into the air passage 24 and the back air layer 25 by the first partition plate 2 and the second partition plate 3. Note that the air passage 24 and the rear air space 25 are partitioned so that a space for the construction vehicle 31 to travel in the air passage 24 is secured.

  Here, the through holes provided in the first partition plate 2 and the second partition plate 3 are small holes, circular holes, odd-shaped holes, slit-shaped holes, louver fin-shaped holes, cross holes, and any other arbitrary holes. It is a hole having a shape, and is preferably made of at least one of these. In the present embodiment, the through holes are circular holes.

  Further, when reducing the low-frequency pressure fluctuation, the opening ratio of the first partition plate 2 and the second partition plate 3 is 1% or more and 10% or less, and the opening diameter of the through hole is 1 mm or more and 120 mm or less. It is preferred that Further, the thickness of the first partition plate 2 and the second partition plate 3 is preferably 1 mm or more and 120 mm or less. By setting the aperture ratio, the aperture diameter, and the plate thickness in such ranges, a high sound absorption coefficient can be obtained in a frequency band of 20 Hz or less.

  Further, the first partition plate 2 and the second partition plate 3 are preferably made of an aluminum plate member or a stainless member from the viewpoint of recycling and rust prevention. Moreover, many through-holes provided in the first partition plate 2 and the second partition plate 3 may be formed by punching or embossing.

  FIG. 4 is a cross-sectional view of the shaft 23 when FIG. 1 is viewed from the B direction. The air passage 24 of the wide section 23a communicates with the internal space of another section.

  Then, as shown in FIG. 2, the wall surface of the inclined shaft 23 (the ceiling surface 23 u, the left side surface 231, and a part of the floor surface 23 d) serves as a substitute for the back plate in the pressure fluctuation reduction structure using the perforated plate. Then, the first partition plate 2 and the second partition plate 3, the back air layer 25, and the wall surface of the inclined shaft 23 (the ceiling surface 23u, the left side surface 231 and a part of the floor surface 23d) are porous. A pressure fluctuation reduction structure using a plate is configured.

  As shown in FIG. 1, when a vehicle passes through the tunnel main shaft 21, the low-frequency pressure fluctuation generated in the tunnel main shaft 21 propagates through the inclined shaft 23 and is released to the outside 22 to generate low-frequency air vibration. Affect the surrounding environment. In addition, noise generated when the vehicle passes through the branch with the inclined shaft 23 propagates through the inclined shaft 23 and is released to the outside 22. In addition, noise such as blasting noise in tunnel construction propagates through the shaft 23 and is released to the outside 22. In addition, noise generated from the ventilation fan propagates through the shaft 23 and is released to the outside 22.

  However, as shown in FIG. 2, the first partition plate 2 and the second partition plate 3, the back air layer 25, and the wall surface of the inclined shaft 23 (the ceiling surface 23 u, the left side surface 231, and the floor surface 23 d). And a part thereof) constitute a pressure fluctuation reduction structure using a perforated plate. Therefore, when low-frequency pressure fluctuations and low-frequency noise passing through the air passage 24 pass through the through holes of the first partition plate 2 and the second partition plate 3, damping action occurs due to viscosity or pressure loss. Specifically, a low frequency pressure fluctuation has a damping effect due to pressure loss, and a low frequency noise has a viscosity damping effect. Due to this damping action, low-frequency pressure fluctuations and low-frequency noise are converted into thermal energy, so that low-frequency pressure fluctuations and low-frequency noise are attenuated. Thus, low-frequency pressure fluctuation and low-frequency noise can be reduced.

  Here, in the first partition plate 2 and the second partition plate 3, the area of the porous portion having a large number of through holes is set according to the frequency of the pressure fluctuation to be reduced and the volume of the back air layer 25. I do. As a result, it is possible to reduce pressure fluctuation at a low frequency of 20 Hz or less and low frequency noise in a 20 to 200 Hz band. When reducing low-frequency noise, the volume of the back air layer 25 is reduced, and the ratio of the cross-sectional area of the air passage 24 is increased.

  By replacing the wall surface of the shaft 23 with the back plate, it is only necessary to dispose the first partition plate 2 and the second partition plate 3 in the shaft 23, so that the installation cost can be reduced. Further, since the pressure fluctuation reducing structure using the perforated plate is sealed by the back plate, it receives the pressure of the pressure fluctuation passing through the air passage 24. Therefore, it is necessary to design the strength of the frame structure 44 in accordance with this. However, in this structure, since only the first partition plate 2 and the second partition plate 3 are installed, the pressure received is small. The pressure of the pressure fluctuation passing through the air passage 24 is received by the wall surface of the shaft 23. Further, this structure is lighter than the pressure fluctuation reducing structure using a perforated plate. Therefore, the frame structure can be simplified. Thereby, the construction cost can be reduced.

  In addition, since the space between the first partition plate 2 and the second partition plate 3 and the wall surface of the shaft 23 is all behind the air layer 25, there is no wasteful space between the wall and the wall surface of the shaft 23. Therefore, the sectional area of the shaft 23 can be effectively utilized.

  Therefore, it is possible to reduce the construction cost and effectively utilize the cross-sectional area of the shaft 23 to reduce low-frequency pressure fluctuation and low-frequency noise.

  Further, by providing the first partition plate 2 and the second partition plate 3 in the wide section 23a having a larger sectional area than the other sections to reduce the pressure fluctuation, the space in the other sections can be effectively used. Can be.

  In the present embodiment, as shown in FIG. 2, the first partition plate 2 and the second partition plate 3 separate the air passage 24 from the air layer 25 behind, so that the wall surface of the air passage 24 The first partition plate 2 and the second partition plate 3 have two surfaces. However, the first partition plate 2 may be extended to the ceiling surface 23u to partition the air passage 24 and the back air layer 25, so that the wall surface of the air passage 24 may be one surface. Further, three wall surfaces of the air passage 24 may be provided by providing another partition plate which is disposed opposite to the side surface 23r at a predetermined interval from the right side surface 23r of the inclined shaft 23 in the drawing. Furthermore, four wall surfaces of the air passage 24 may be provided by providing another partition plate disposed at a predetermined distance from the floor surface 23d of the inclined shaft 23 and facing the floor surface 23d.

  Further, in the present embodiment, the entire surface of the first partition plate 2 and the second partition plate 3 is a porous portion, but a part of the first partition plate 2 and the second partition plate 3 is a porous portion. There may be. Further, in order to widen the frequency band to be reduced, a porous portion having a different aperture ratio is provided in the first partition plate 2 or the second partition plate 3 along the longitudinal direction of the shaft 23 or a direction orthogonal thereto. A plurality may be provided.

  Further, in the present embodiment, as shown in FIG. 2, the first partition plate 2 and the second partition plate 3, the back air layer 25, and the wall surface of the inclined shaft 23 use a pressure variation using a perforated plate. The reduction structure is configured to reduce low-frequency pressure fluctuations and low-frequency noise.For example, a box-shaped pressure fluctuation reduction structure having a space surrounded by a perforated plate, a back plate, and a side plate is included. May be provided along the left side surface 231 of the inclined shaft 23 in the rear air layer 25 in the drawing. In this case, low-frequency pressure fluctuations of 20 Hz or less are reduced between the through holes of the first partition plate 2 and the second partition plate 3 and the air layer 25 behind the first partition plate 2 and the second partition plate 3. The low-frequency noise in the 20 to 200 Hz band that has passed through the through hole of the plate 3 may be reduced by the box-shaped pressure fluctuation reduction structure provided along the side surface 231.

(Pressure evaluation)
Next, in the pressure fluctuation reduction structure 1 of the present embodiment and the shaft structure 51 of Patent Document 1, the area of the porous portion having a large number of through holes is changed to open the opening 22 on the outside 22 side of the inclined shaft 23 (headhole). The pressure observed at a point 10 m from was evaluated. Hereinafter, the shaft structure 51 of Patent Document 1 is referred to as a conventional pressure fluctuation reduction structure 51. 5A and 5B are schematic views of the pressure fluctuation reducing structure 1 of the present embodiment, which are cross-sectional views orthogonal to the longitudinal direction of the shaft 23. FIG. 6 is a schematic view of a conventional pressure fluctuation reducing structure 51, which is a cross-sectional view orthogonal to the longitudinal direction of the shaft 23.

  The pressure fluctuation reduction structure 1 shown in FIG. 5A has a perforated plate on the entire surface of the first partition plate 2 and no through-hole in the second partition plate 3, and has a single perforated plate. The pressure fluctuation reducing structure 1 shown in FIG. 5B has two perforated plates in which the entire surface of each of the first partition plate 2 and the second partition plate 3 is a porous portion.

  In the conventional pressure fluctuation reduction structure 51 shown in FIG. 6, the air passage 24 and the back air layer 25 are separated by a perforated plate 52 having a large number of through holes. The conventional pressure fluctuation reducing structure 51 shown in FIG. 6 is a structure having the same performance as the pressure fluctuation reducing structure 1 shown in FIG. 5A. This is because the length ratio between the back air layer and the perforated plate is the same, and the structure has the same performance.

  The pressure was evaluated by the pressure fluctuation reducing structure 1 (perforated plate 1) shown in FIG. 5A, the pressure fluctuation reducing structure 1 (perforated plate 2) shown in FIG. 5B, and the conventional pressure fluctuation reducing structure shown in FIG. 51 (conventional type). FIG. 7 shows the relationship between the relative pressure gradient value of the pressure fluctuation in the tunnel main shaft 21 and the relative pressure at the entrance of the inclined shaft 23. In FIG. 7, the horizontal axis represents the pressure gradient value of the relative pressure fluctuation in the tunnel main shaft 21 connected to the shaft 23. The pressure value when the pressure fluctuation propagates through the shaft 23 and is released to the outside 22 increases as the relative pressure gradient value increases. In FIG. 7, the horizontal axis represents the largest value among the evaluation values of the pressure gradient in the tunnel main shaft 21 when no countermeasures are taken (when the pressure fluctuation reduction structure 1 and the conventional pressure fluctuation reduction structure 51 are not provided). The value is a relative pressure gradient value obtained by normalizing the pressure gradient value in the tunnel main shaft 21. In addition, the vertical axis represents the oblique shaft when the evaluation value of the pressure gradient in the tunnel main shaft 21 reaches the maximum value when no measures are taken without providing the pressure fluctuation reducing structure 1 or the conventional pressure fluctuation reducing structure 51. The pressure value at the wellhead 23 is a relative pressure obtained by normalizing the pressure value at the wellhead 23.

  From FIG. 7, it can be seen that the pressure at the wellhead of the shaft 23 is reduced by the porous portion. In particular, the reduction effect is large when the pressure gradient is large, and the pressure fluctuation reduction structure 1 (one perforated plate) shown in FIG. 5A has a reduction effect of about 40%. The conventional pressure fluctuation reducing structure 51 (conventional type) shown in FIG. 6 has a structure similar to the pressure fluctuation reducing structure 1 (one surface of the perforated plate) shown in FIG.

  Also, it can be seen that the pressure fluctuation reducing structure 1 (two perforated plates) shown in FIG. 5B has a smaller reduction effect than the pressure fluctuation reducing structure 1 (one perforated plate) shown in FIG. 5A. This is because the pressure fluctuation reducing structure 1 (one perforated plate 1) shown in FIG. 5A has a lower air layer 25 per area of the porous portion than the pressure fluctuation reducing structure 1 (two perforated plates) shown in FIG. 5B. This is because the volume is large and the structure is suitable for the frequency characteristics of low-frequency pressure fluctuation.

  5A and 5B, assuming that the length in the depth direction (longitudinal direction) is the same, the volume of the back air layer 25 per area of the perforated portion is determined by cutting the back air layer 25 per length L of the perforated portion. Consider the area S. The soundproofing performance of the pressure fluctuation reducing structure 1 in which the wall of the shaft 23 is substituted for the back plate in the pressure fluctuation reducing structure using a perforated plate is a cross-sectional area S of the rear air layer 25 in a cross section orthogonal to the longitudinal direction of the shaft 23. Is divided by the length L of the porous portion. In FIG. 5A, when the cross-sectional area S of the back air layer 25 is divided by the length L of the perforated plate 52, S / L = 5 [m]. On the other hand, in FIG. 5B, when the sectional area S of the back air layer 25 is divided by the length L of the perforated plates 52 and 53, S / L = 2.5 [m].

  As shown in FIG. 6, when the length L of the perforated plate 52 separating the air passage 24 and the back air layer 25 is the same as the width of the back air layer 25 in the length direction of the perforated plate 52, S / The value of L represents the thickness of the back air layer 25. That is, the value of S / L can be said to be the air layer thickness. In the pressure fluctuation reducing structure 1 (two perforated plates 2) shown in FIG. 5B in which this value is 2.5 m, the pressure reduction effect is small. Can be suitably reduced. The effect is considered to be the same even if the value of S / L is larger than 10 m. Therefore, from the viewpoint of saving space, the value of S / L is preferably 10 m or less.

(effect)
As described above, according to the pressure fluctuation reducing structure 1 according to the present embodiment, the first partition plate 2 and the second partition plate 3 allow the internal space of the shaft 23 to be separated from the air passage 24 and the rear air layer 25. It is divided into. Then, the wall surface (a part of the ceiling surface 23u, the left side surface 23l, and the floor surface 23d) of the inclined shaft 23 becomes a substitute for the back plate in the pressure fluctuation reduction structure using the perforated plate, and thus the first partition plate. The second and second partition plates 3, the rear air layer 25, and the wall surface of the inclined shaft 23 constitute a pressure fluctuation reducing structure using a perforated plate. Therefore, when low-frequency pressure fluctuations and low-frequency noise passing through the air passage 24 pass through the through holes of the first partition plate 2 and the second partition plate 3, damping action occurs due to viscosity or pressure loss. Due to this damping action, low-frequency pressure fluctuations and low-frequency noise are converted into thermal energy, so that low-frequency pressure fluctuations and low-frequency noise are attenuated. Thus, low-frequency pressure fluctuation and low-frequency noise can be reduced.

  Then, by replacing the wall surface of the shaft 23 with the back plate, it is only necessary to install the first partition plate 2 and the second partition plate 3 in the shaft 23, so that the installation cost can be reduced. Further, since the pressure fluctuation reducing structure using the perforated plate is sealed by the back plate, it receives the pressure of the pressure fluctuation passing through the air passage 24. Therefore, it is necessary to design the strength of the frame structure in accordance with this. However, in this structure, since only the first partition plate 2 and the second partition plate 3 are installed, the pressure received is small. Further, this structure is lighter than the pressure fluctuation reducing structure using a perforated plate. Therefore, the frame structure can be simplified. Thereby, the construction cost can be reduced. In addition, since the space between the first partition plate 2 and the second partition plate 3 and the wall surface of the shaft 23 is all behind the air layer 25, there is no wasteful space between the wall and the wall surface of the shaft 23. Therefore, the sectional area of the shaft 23 can be effectively utilized.

  Therefore, it is possible to reduce the construction cost and effectively utilize the cross-sectional area of the shaft 23 to reduce low-frequency pressure fluctuation and low-frequency noise.

  Also, the first partition plate 2 and the second partition plate 3 are provided in the wide section 23a having a larger sectional area than the other sections to reduce low-frequency pressure fluctuation and low-frequency noise, thereby reducing the frequency of other sections. Space can be used effectively.

  The soundproofing performance of this structure in which the wall surface of the shaft 23 is used as a substitute for the back plate in the pressure fluctuation reducing structure using a perforated plate is such that the cross-sectional area S Is divided by the length L of the porous portion. When the length L of the porous portion of the first partition plate 2 and the second partition plate 3 that partition the air passage 24 and the back air layer 25 is the same as the width of the back air layer 25 in the length direction of the porous portion. The value obtained by dividing the cross-sectional area S of the back air layer 25 by the length L of the porous portion represents the thickness of the back air layer 25. By setting this value to more than 2.5 m and 10 m or less, the pressure can be suitably reduced.

(Modification of this embodiment)
As described above, the embodiments of the present invention have been described, but they are merely specific examples, and do not limit the present invention in particular. Specific configurations and the like can be appropriately changed in design. Further, the actions and effects described in the embodiments of the invention merely enumerate the most preferable actions and effects resulting from the present invention, and the actions and effects according to the present invention are described in the embodiments of the present invention. It is not limited to what was done.

  For example, the wide section 23a in which the pressure fluctuation reducing structure 1 of the present embodiment is provided may be provided continuously in the longitudinal direction of the shaft 23 as shown in FIG. 8 which is a perspective view. FIG. 9 shows the relationship between the pressure gradient value of the pressure fluctuation in the tunnel 21 and the relative pressure at the entrance of the shaft 23. As shown in FIG. 1, two wide sections 23a having a predetermined length are provided apart from each other in the longitudinal direction (division), and as shown in FIG. 8, two wide sections 23a having a predetermined length are provided. If the sum of the lengths of all of the wide sections 23a is the same between the case where (a) and (b) are connected (continuous), the effect of reducing the pressure is the same.

DESCRIPTION OF SYMBOLS 1 Pressure fluctuation reduction structure 2 1st partition plate 3 2nd partition plate 21 tunnel main shaft 22 outside 23 inclined shaft 23a wide section 23d floor surface 23l, 23r side surface 23u ceiling surface 24 air passage 25 air layer behind 31 construction vehicle 41 tunnel Main shaft 42 External 43 Vertical shaft 44 Frame structure 45 Space 51 Vertical shaft structure (pressure fluctuation reduction structure)
52,53 Perforated plate 61 Vehicle

Claims (4)

A tunnel main shaft through which a vehicle passes, and a pressure fluctuation reducing structure provided in a tunnel including an inclined shaft for communicating the tunnel main shaft with the outside,
A first partition plate provided on at least one of two side surfaces of the gallery, and arranged at a predetermined distance from the side surface to face the side surface;
A second partition plate that is provided on at least one of two walls forming a ceiling and a floor of the gallery, and is disposed to face the wall with a predetermined gap between the wall and the wall;
Has,
At least one of the first partition plate and the second partition plate has a porous portion having a large number of through holes,
A pressure fluctuation reducing structure, wherein the inner space of the gallery is divided into an air passage and a back air layer by the first partition plate and the second partition plate. In the tunnel, a plurality of wide sections are provided in the longitudinal direction of the tunnel, the wide section is a section whose cross-sectional area in a direction orthogonal to the longitudinal direction of the tunnel is larger than other sections.
The pressure fluctuation reducing structure according to claim 1, wherein the first partition plate and the second partition plate are provided in the wide section. In a cross section orthogonal to the longitudinal direction of the tunnel, a value obtained by dividing a cross-sectional area [m ² ] of the rear air layer by a length [m] of the porous portion is more than 2.5 m and 10 m or less. The pressure fluctuation reducing structure according to claim 1 or 2, wherein: An aperture ratio of the first partition plate and the second partition plate is 1% or more and 10% or less;
The opening diameter of the through hole is 1 mm or more and 120 mm or less,
The pressure fluctuation reducing structure according to any one of claims 1 to 3, wherein the thickness of the first partition plate and the second partition plate is 1 mm or more and 120 mm or less.

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