JPH02275300A - Sound isolation device for tunnel construction work - Google Patents

Abstract

PURPOSE:To make it simple to handle sound isolation sheets and simple to enter a sound isolation device or exit from it and to move it further into the front by dividing a sound isolation sheet into a central sound isolation sheet and side sound isolation sheets on the right and left and making the central sound isolation sheet openable and closable and dividing a channel to support the sheets into a plurality of sections along the longitudinal cross section of the tunnel opening and at the same time making them removable. CONSTITUTION:A sound isolation sheet SS is divided into the central upper sound isolation sheet SC1, central lower sound isolation sheet SC2, and the left sound isolation sheet SL positioned to the right and left to those sheets SC1 and SC2, and a right sound isolation sheet SR, and the central lower sheet SC2 is openable and closable. A sheet support channel 22 runs along the longitudinal cross section of the tunnel opening and it is divided symmetrically with respect to right and left into l1, l2, l3, and l4, the four sections and they have a plurality of fixed brackets 23 welded which extend in the direction perpendicular to the channel 22 in the direction of the tunnel excavation. The fixed brackets 23 is fixed by an anchor bolt 23. When the bolt 23 is loosened the support channel 22, bracket 23, fixing device 10A, sheets, etc. can be moved. A sound isolation packing 29 between the support channel 22 and the concrete construction 26 raises the effect of sound isolation.

Description

TECHNICAL FIELD The present invention relates to a sound insulation device for insulating noise generated during tunnel construction.

"Prior art and its problems" Tunnel construction generally involves blasting work, which generates extremely loud noise. This noise did not become a social problem while tunnel construction was being carried out only deep in the mountains, far away from people's homes, but it has become a major social problem in recent years as tunnel construction sites and people's homes have come closer together.

Against this background, various sound insulation devices are already in use. In the past, a structure was used in which the tunnel opening was closed with iron plates, but this was not only difficult to work with, but also had little sound insulation effect.

In recent years, with the development of sound insulating sheets, various devices have been proposed for using them in tunnel construction. One of them is
Weld and fix the guide rail along the shoring provided in the longitudinal section of the tunnel opening (referring to the section perpendicular to the extension direction),
The structure is such that roller bodies provided at predetermined intervals on the edge of the sound insulation sheet are inserted through this guide rail to suspend and support the sound insulation sheet.

However, since this sound insulation device is based on the technical idea of closing the entire tunnel opening with a series of sound insulation sheets, the weight of the entire sound insulation sheet is extremely thick (which makes it difficult to handle. No matter what kind of work you do, such as lifting, it is extremely difficult to handle a sound insulation sheet that is approximately 10 meters long and wide.Furthermore, with this conventional device, the guide rail is welded to the support, so it becomes difficult to handle as the tunnel construction progresses. In addition, the guide rail must be added to the back of the tunnel, which is not economical.

``Object of the Invention'' The present invention aims to provide a sound insulation device for a tunnel using a sound insulation sheet, in which the sound insulation sheet is easy to handle and it is relatively easy to enter and exit the sound insulation device. do.

Another object of the present invention is to obtain a sound insulation device that can be easily moved to the back as tunnel construction progresses.

A further object of the present invention is to obtain a sound insulation device that can enhance the sound insulation effect.

``Summary of the Invention'' The present invention first makes it easier to handle the sound insulation sheet by changing the conventional sound insulation device, in which a single sound insulation sheet was used to block the tunnel opening, to a divided structure. . When dividing the sound insulation sheet, the sound insulation sheet is divided into at least a central sound insulation sheet and side sound insulation sheets on the left and right sides of the sound insulation sheet when viewed from the front of the tunnel opening, so that the central sound insulation sheet can be opened and closed. It is a feature. The center sound insulating sheet can be further divided into an upper center sound insulating sheet and a lower center sound insulating sheet, and the lower center sound insulating sheet can be opened and closed.

If the sound insulation sheet is divided in this way and the central sound insulation sheet can be opened and closed, only the central sound insulation sheet can be opened when accessing dump truck construction materials, etc. You can close this.

In addition, the present invention provides a sound insulation device for tunnel construction, which has a support channel provided along the longitudinal section of the tunnel opening, and a sound insulation sheet whose peripheral edge is fixed to the support channel, in order to facilitate relocation to the back of the tunnel. The support channel is divided into a plurality of parts along the longitudinal section of the tunnel opening, and is characterized in that the support channel is detachable from the tunnel opening. The support channel can be made removable, for example, by means of anchor bolts, and with this structure of removability using anchor bolts, relocation is much easier than with conventional devices in which guide rails are welded to the shoring.

Furthermore, the present invention proposes a frame structure that can reliably support especially the periphery of the divided sound insulation sheet.

This frame structure consists of a support channel provided along the longitudinal section of the tunnel opening, a pair of vertical dividing columns whose upper part is connected to the support channel, and which divides the tunnel opening into a central opening and left and right openings. A central sound insulation sheet that can be opened and closed is installed between the vertically divided columns of the
The present invention is characterized by comprising left and right sound insulating sheets supported between both sides of a pair of vertically divided columns and a support channel.

A horizontal dividing column may be further provided between the upper portions of the pair of vertically dividing columns, and above the horizontally dividing column, a center upper sound insulating sheet and a lower center sound insulating sheet that can be opened and closed can be provided at the bottom.

The periphery of the divided sound insulation sheet can be securely fixed to these support channels, vertical division columns, and horizontal division columns, thereby achieving a high sound insulation effect.

"Embodiments of the Invention" The present invention will be described below with reference to illustrated embodiments. The illustrated embodiment is an example in which the center sound insulating sheet is divided into a center upper sound insulating sheet and a center lower sound insulating sheet. The series in Fig. 1 mainly shows the structure of the sound insulation sheet, the series in Fig. 2 mainly shows the structure of the support frame, and the series in Fig. 3 mainly shows the suspension and fixing structure of the sound insulation sheet. The series shown in FIG. 4 mainly shows a winding-up/closing structure for the central lower sheet.

The sound insulation sheet SS is, as shown in FIG. 1A and 18, a center upper sound insulation sheet (hereinafter simply referred to as the center upper sheet) SC.
I and lower center sound insulation sheet (same lower center sheet) SC2
It is divided into a left sound insulation sheet SL and a right sound insulation sheet SR located on the left and right sides of these sheets. The basic idea of the present invention is that by dividing the sound insulation sheet SS in this way,
It is easy to handle each divided sheet, and the central lower sheet S
By making C2 openable and closable, the purpose is to avoid any substantial hindrance to the transportation of materials into the tunnel. The right sound insulation sheet SR is provided with an opening for a ventilation duct.

The periphery of these split sheets has lobes (or core material)
r is provided. First, on the periphery of the left sound insulation sheet SL, right sound insulation sheet SR, and center upper sheet SC1 along the tunnel opening, first and second
A fixing device 10A having the structure shown in Fig. 6 is placed at the same towing position B, and a towed device (also a fixing device) 10B having the structure shown in Figs. 1D and IE.
are provided for each. In other words, the left sound insulation sheet SL
A bag-shaped portion S is formed on the periphery of the right sound insulating sheet SR1 and the central upper sheet S01 along the tunnel opening, and a portion of the periphery including the bag-shaped portion S is provided with fixed positions A and traction positions B.
A notch k is formed corresponding to the position of. On the other hand, the fixing device 10A and the towed device 10B each have a fixing bolt 11 and a fixing plate 12 extending in opposite directions. 11a and an insertion hole 12a are formed. When the peripheral lobe r is inserted into the bag-shaped portion S, the peripheral lobe r is inserted into the eye hole 11a and the insertion hole 12a.

The towed tool 10B differs from the fixture 10A in that it has a rotatable roller 14 at the tip of the fixing plate 12. A wedge driving hole 15 is formed in the fixing plate 12, and a fixing nut 16 is screwed into the fixing bolt 11. In addition, in FIGS. 1E and 16, the fixing bolt 11 and the left sound insulation sheet SL (right sound insulation sheet SR1 center upper sheet 5
CI) are drawn overlapping each other, but in reality, fixing bolt 1
1 escapes from the sound insulation sheet.

Next, a preferred embodiment of the frame structure to support these divided sheets will be described with reference to the series of FIG. As is well known, on the inner surface of the tunnel opening, supports 21 (see FIG. 2C) along the longitudinal section of the tunnel are provided at appropriate intervals in the excavation direction. One of the features of the present invention is that the support channel 22 is removably attached along the tunnel opening without directly using the support 21.

The support channel 22 is divided into a plurality of parts along the longitudinal section of the tunnel opening. In this embodiment, it is symmetrically divided into four support channels 22, sections β1, °C2, I23, and flood 4, and each support channel 22 is divided into four support channels 22:
A plurality of fixing brackets 23 (second
0.2D diagram) is welded to the base. Support channel 2
At the connection part between 2 and 22, as shown in Fig. 2B,
The left and right fixing brackets 23 are welded to one of the adjacent support channels 22, as shown by W, so that the support channels 22 are continuous.

The fixing bracket 23 has a bolt insertion hole 24, and an anchor bolt 25 inserted through the bolt insertion hole 24.
The support channel 22 is fixed by being screwed into a bolt receiver 27 embedded in a concrete structure 26 forming the tunnel opening. Therefore, anchor bolt 2
By loosening 5, the support channel 22 can be removed. Bolt receivers 27 can be easily embedded within concrete structure 26 using known techniques, so that support channels 22 can be easily relocated.

In the figure, the support channel 22 is provided to match the position of the shoring 21, but this is not necessarily necessary.

And this support channel 22 and concrete structure 2
6, a sound insulating packing 29 (FIG. 2C) is inserted. Generally, the surface of the concrete structure 26 is not smooth, and a gap is created between the support channel 22 and this gap impairs the sound insulation effect. By inserting the sound insulation packing 29, a high sound insulation effect can be obtained.

However, the present invention does not preclude fixing the support channel 22 by means other than the anchor bolts 25. That is, even if the support channel 22 is joined to the concrete structure 26 or the shoring 21 by welding or adhesive, the effect of the divided sheet structure can be obtained.

This support channel 22 is formed from C-shaped steel,
Its bottom plane 22a is oriented in the longitudinal cross-sectional direction of the tunnel opening. and the bottom plane 22 of this support channel 22
A corresponds to the fixed position A and the towed position B described for the split sheet. Fixed position A° and towed position B
A through hole 28 is bored in each of the holes. This through hole 28 is for inserting the fixing device 10A of the peripheral edge of the divided sheet and the fixing plate 12 of the towed device 10B.

Also within the tunnel opening, in conjunction with the support channel 22 provided as described above, are a pair of vertical split struts 3.
0.30 is provided. This pair of vertically dividing columns 30 divides the inside of the tunnel opening into a central area corresponding to the center upper sheet S01 and the center lower sheet 1-3C2, and a left sound insulation sheet SL area and a right sound insulation sheet SR area on both sides. The upper end of the fixing bolt 31 (second E
(Fig.) is fixed to the support channel 22 through the support channel 22.

Each vertically divided column 30 has a horizontal column 32,33 extending into the left sound insulation sheet SL (right sound insulation sheet SR) area. As shown in FIG. 2D, the horizontal struts 32 and 33 have bolt-nut telescopic mechanisms 32a and 3 at their tips.
3a, and the bolt/nut expansion/contraction mechanisms 32a, 33a
The ends of the horizontal struts 32, 33 are brought into close contact with or fixed to the support channel 22 through the support channels 22, 32, 33, and 32, respectively. Also, the vertical split column 3
0 and the support channel 22 are also suitably connected by turnbuckles 34, shown in chain lines in FIG. 2A, to provide a strong frame structure.

Between the upper parts of the pair of vertically divided columns 30 is a central upper sheet S.
They are connected by a horizontal dividing column 35 that separates the C1 area and the central lower seat SC2 area. These vertically divided columns 30 (and horizontally divided columns 35), as shown in FIG. , 30d, a gap is created between the half channels 30a and 30b. The peripheral lobes r of the corresponding peripheral edges of the left sound insulation sheet SL, the right sound insulation sheet SR1, the center upper sheet S01, and the center lower sheet SC2 are connected to the fixing bolts 30c and nuts 30.
When d is loosened, the half channels 30a and 30b
and be moved as necessary.

When sound insulation is required, tighten the fixing bolts 30c and nuts 30d and securely secure the periphery of the left sound insulation sheet SL, right sound insulation sheet SR1, center upper sheet SCI, or center lower sheet SC2 between the half channels 30a and 30b. Together with the action of the pinching and the peripheral lobe r, these divided sheets are prevented from moving.

Further, a screw jack 37 is provided at the lower end of the vertically divided column 30. This screw jack 37 is attached to the handle 3
When 7a is rotated, the support plate 37b at the lower end moves up and down, and the lower ends of the center lower sheet S02, the left sound insulation sheet SL, and the right sound insulation sheet SR are sandwiched and held between the support plate 37b and the ground. Ru.

Next, the structure for lifting the above divided sound insulating sheet, its procedure, and the structure for fixing it to the support channel 22 will be explained with reference to the series of FIGS.

In this embodiment, the left sound insulation sheet SL and the right sound insulation sheet SR are lifted by one hoisting system, and the center upper sheet S01 is hoisted by another hoisting system. In FIG. 3A, support channel 22 is shown unfolded and drawn as a straight line. A part of this support channel 22 is provided in a position corresponding to the rightmost traction position B of the left sound insulation sheet SL and right sound insulation sheet SR in FIG. 1B, and the rightmost traction position B of the center upper sheet SCI.
A hoisting lobe fixing part WF is provided, and furthermore, a roller part WR is provided corresponding to each traction position B. Left sound insulation sheet S
A towing device 10B is provided at the towing position B of the right sound insulating sheet SR1 and the center upper sheet SCI.

FIG. 3C shows a specific example of this hoisting lobe fixing part WF. An anchor bolt 25 that fixes the support channel 22 is integrally provided with a support ring 40, and a wire fixing hook 41 is hooked onto the support ring 40. This wire fixing hook 41 has a hoisting wire Wl.
(For left sound insulation sheet SL, right sound insulation sheet SR), W2 (
One end of the central upper sheet (for SC1) is locked.

The support channel 22 further includes this wire fixing hook 4.
1, a bracket 43 with rollers 42 is fixed.

FIG. 3D shows a specific example of the roller portion WR. A fixing bracket 23 that fixes the support channel 22 includes a roller 4.
A bracket 45 having a bracket 4 is integrally provided. Further, the support channel 22 is provided with a roller 44 corresponding to the support channel 22.
Similar to the hoisting lobe fixing part WF, a bracket 43 having a roller 42 is fixed.

The hoisting wire W1 first connects its tip to the hoisting lobe fixing part W.
After the wire fixing hook 41 of F is fixed, the roller 42
Turn the hook, then turn the left sound insulation sheet SL, the right sound insulation sheet S
The hook is rotated by the roller 14 at the traction position B on the R periphery. After that, the rollers 42 and 4 of the roller portion WR are sequentially
4. The wire is turned around the roller 14 at the pulling position B, and finally it is guided to the hoisting device 46. (When the hoisting device 46 is driven and the hoisting wire W1 is wound up, the left sound insulation sheet SL and the right The sound insulating sheet SR is eventually pulled up to a position along the support channel 22.

Similarly, the hoisting wire W2 has its tip hooked to the wire fixing hook 41 of the hoisting lobe fixing part WF, and then
2, and then the roller 14 at the traction position B on the periphery of the center upper sea)-5CI is turned. After that, the rollers 42 and 44 of the roller portion WR and the roller 14 at the traction position B are sequentially hooked and turned, and finally the same hoisting device (
(not shown). Drive the hoisting device to remove the hoisting wire W2
As the center upper sheet S01 is wound up, the central upper sheet S01 is eventually pulled up to a position along the support channel 22.

In this pulled-up state, the fixing plates 12 of the fixing devices 10A and towed devices 10B on the peripheral edge of each divided sheet are in a state close to the through holes 28 of the support channels 22, respectively. In this state, the 20.2G
As shown in Figures 2 and 2H, a fixing channel 50 of an appropriate length is fitted, and the periphery of the divided sheet is held down by this fixing channel 50. The fixing plate 12 is made to protrude from the through hole 28 to the opposite side of the support channel 22, and a retaining wedge 51 is driven into the wedge driving hole 15. With the fixing plate 12 prevented from being removed in this way, when the fixing nut 16 is tightened, the fixing channel 50 firmly sandwiches and fixes the periphery of the divided sheet between it and the bottom plane 22a of the support channel 22. be able to.

52 indicates a sound insulation packing. Chapter 20.2G and 2H
The figure shows the fixture 10A, but the towed tool 1
The fixing mode for 0B is also exactly the same.

The series in FIG. 4 shows the winding and opening structure of the central lower sheet SC2. A hoisting shaft 55 is rotatably spanned between the upper portions of the pair of vertically divided columns 30, and the upper end portion of the central lower sheet S02 is fixed to this hoisting shaft 55. The peripheral lobes r at both edges of the central lower sheet SC2 are:
It is housed in a pair of vertically divided columns 30, and can be raised and lowered by loosening the fixing bolt 30c and nut 30d. A gear 56 is provided coaxially with the hoisting shaft 55, and this gear 56 meshes with a gear 58 provided integrally with a drive shaft 57 parallel to the hoisting shaft 55. A chain wheel 59 is further integrally provided on the drive shaft 57, and this chain wheel 5
A chain 60 is wound around 9. 61 is a load brake.

The above mechanism is equivalent to a well-known chain block, and when the chain wheel 59 is rotated via the chain 60, the hoisting shaft 55 is rotated by a reduction mechanism based on the number of teeth of each gear. Sheet S02 is rolled up or lowered.

The load brake 61 prevents the central lower seat SC2 from falling due to its own weight. Therefore, by rotating the chain wheel 59 via the chain 60, the central lower seat SC2 is closed as shown in FIG. 4A, or the fourth
It can be opened as shown in Figure B. When open, dump trucks can enter and exit the tunnel,
Materials can be transported freely, and when closed, it can provide sound insulation. When performing blasting work, the fixing bolts 30c and nuts 30d are tightened to firmly fix the peripheral edge of the central lower sheet S02 to the vertically divided columns 30.

In addition, the sound insulation sheet structure of the present invention usually aims at more effective sound insulation by providing a plurality of sheets spaced apart by an appropriate amount.

In the above embodiment, the central sound insulating sheet is the central upper sheet S.
Although it is divided into the CI and the central lower sheet SC2, they may be provided integrally. In addition, left sound insulation sheet SL, right sound insulation sheet SR1, center upper sheet SC1, and center lower sheet SC
The structure of the illustrated embodiment for fixing the peripheral edges of the parts 2 and 2 has the feature that these can be fixed reliably and with a high sound insulation effect, but the present invention is not limited to these supporting and fixing structures.

"Effects of the Invention" As described above, the present invention divides a sound insulation sheet into at least a central sound insulation sheet and left and right side sound insulation sheets when viewed from the front of a tunnel opening, and opens and closes the central sound insulation sheet. Therefore, when accessing dump trucks, construction materials, etc., only the central sound insulation sheet needs to be opened, and it can be easily closed during blasting work.

The present invention also provides a sound insulation device for tunnel construction, which includes a support channel provided along the longitudinal section of the tunnel opening, and a sound insulation sheet whose periphery is fixed to the support channel. Since it is divided into a plurality of parts and can be attached to and detached from the tunnel opening via anchor bolts, it can be easily moved to the back as tunnel construction progresses, making it economical.

Furthermore, the present invention particularly provides for the periphery of the divided sound insulating sheet to
The tunnel opening can be reliably fixed to a support channel provided along the longitudinal section of the tunnel opening and a pair of vertical dividing columns whose upper portions are connected to the support channel and which divide the tunnel opening into a central opening and left and right openings. , it is possible to obtain more reliable support and fixation and a sound insulation effect based on this.

[Brief explanation of drawings]

Figures 1A to IE mainly show examples of sound insulation sheets used in the sound insulation device of the present invention. Figure 1A is a front view showing the divided structure of the sound insulation sheet, and Figure 1B shows the divided structure in more detail. Figure 1C is a side view of the divided sound insulation sheet having a ventilation duct; Figure 1D is a front view of a towed device provided on the periphery of the sound insulation sheet; Figure 1E is a side view of Figure 1D. , Fig. 1F is a front view of a fixture provided on the periphery of the sound insulating sheet, and Fig. 1G is a side view of Fig. 1F. 2A to 2H mainly show the fixed frame structure of the sound insulation sheet used in the sound insulation device of the present invention. FIG. 2A is a front view of the whole, FIG. Figure 2C is a cross-sectional view taken along line C-C in Figures 2A and 2E, Figure 2D is an enlarged front view of the split strut in Figure 2A, and Figure 2E is the fixing of the edge of the sound insulation sheet in the split strut section. 2F is a sectional view taken along line FF in FIG. 2E, 2G is a sectional view showing the structure of the sound insulation sheet fixing part in 2C in more detail, and 2H is a front view showing the structure. 2G is a cross-sectional view taken along line HH in FIG. 2G. Figures 3A to 3D show the winding structure of the sound insulation sheet, Figure 3A is a front view showing the winding state of the hoisting hanging lobe, Figure 3B is a side view of Figure 3A, and Figure 3C is the winding structure. FIG. 3D is a sectional view showing the state of the fixed end portion of the upper suspension lobe; FIG. 3D is a sectional view showing the state of the movable portion of the hoisting suspension lobe. Figures 4A to 4E show the winding structure of the divided sound insulating central sheet, and Figure 4A is a front view of the divided sound insulating central sheet in a closed state, Figure 4B is a front view of the divided sound insulating central sheet in an open state, and Figure 4C The figure is a side view of FIG. 4A, FIG. 4D is an enlarged front view of the hoisting mechanism, and FIG. 4E is a right side view of FIG. 4D. 35...Horizontal division support column, 40...Support ring, 41
...Wire fixing hook, 42.44...Roller, 4
3.45...Bracket, 46...Hoisting device, 50
...fixed channel, 51...removal stopper wedge, 55.
...Hoisting shaft, 59...Chain wheel, 60...Chain, 61...Load brake. A, A'... fixed position, B, B'... towed position, S
S: Sound insulation sheet, SCI: Upper center sound insulation sheet, SC2: Lower center sound insulation sheet, SL: Left sound insulation sheet, SR: Right sound insulation sheet, WF: Hoisting lobe fixing part , WR...roller part, Wl, W2...hoisting wire, S...bagged part, r...peripheral lobe, IOA
...Fixing tool, 10B...Towed tool, 11...Fixing bolt, 12...Fixing plate, 14...Roller,
15... Wedge driving hole, 16... Fixing nut, 21
...Shoring, 22...Support channel, 23...
Fixing bracket, 24... Bolt insertion hole, 25...
Anchor bolt, 26... Concrete structure, 27
...Bolt receiver, 28...Through hole, 29...Sound insulating gasket, 30...Vertical split column, Patent applicant: Deck Kogyo Co., Ltd. Agent Kunio Miura Figure 1A Figure 1D Figure 1E Figure 1F ffl Figure 1G A Figure 2A Figure 2B Figure 4A Figure 4B Figure 4C Figure 4D Figure 4E

Claims (7)

[Claims] (1) In a sound insulation device that closes a tunnel opening with a sound insulation sheet, the sound insulation sheet is divided into at least a central sound insulation sheet and left and right side sound insulation sheets when viewed from the front of the tunnel opening. A sound insulation device for tunnel construction, characterized in that it can be opened and closed. (2) The sound insulation device for tunnel construction according to claim 1, wherein the center sound insulation sheet is further divided into an upper center sound insulation sheet and a lower center sound insulation sheet, and the lower center sound insulation sheet can be opened and closed. (3) In a sound insulation device for tunnel construction, which has a support channel provided along the longitudinal section of the tunnel opening; and a sound insulation sheet whose peripheral edge is fixed to the support channel, the support channel is arranged along the longitudinal section of the tunnel opening. A sound insulation device for tunnel construction, characterized in that it is divided into a plurality of parts and is detachable from the tunnel opening. (4) The sound insulation device for tunnel construction according to claim 3, wherein a packing is inserted between the support channel and the tunnel opening. (5) a support channel provided along the longitudinal section of the tunnel opening; a pair of vertical dividing columns whose upper part is connected to the support channel and which divides the tunnel opening into a central opening and left and right openings; For tunnel construction, comprising: a center sound insulating sheet that can be opened and closed, provided between the divided columns; and left and right sound insulating sheets supported between both sides of a pair of vertically divided columns and a support channel. Sound insulation device. (6) In claim 5, a horizontal splitting post is provided between the upper parts of the pair of vertically splitting posts, a center upper sound insulating sheet is provided above the horizontal splitting post, and a center lower sound insulating sheet is provided that can be opened and closed at the bottom. Sound insulation device for tunnel construction equipped with a sheet. (7) The sound insulation device for tunnel construction according to claim 1, 2, 5 or 6, wherein the openable and closable central sound insulation sheet is made openable and closable by a winding structure on a winding shaft.