Ultra-high edge light steel keel soundproof wall suitable for large space and construction method thereof

Abstract

The application discloses a kind of ultrahigh edge light steel keel sound insulation wall suitable for large space and its construction method, comprising: supporting framework, including construction column, construction beam, multiple keel units, construction column is supported between floor and steel structure beam, construction beam is connected between construction column and steel structure column, construction column, construction beam, steel structure column and steel structure beam are enclosed to form multiple frame openings, multiple keel units are installed in each frame opening along the axial direction of frame opening and are spaced, and the keel unit includes multiple vertical keels and through keel, vertical keel is vertically arranged in frame opening, and through keel is connected to multiple vertical keels;Protective grating is installed on the outside of supporting framework, and the inside of protective grating is paved with enclosure board;Sound insulation board is paved on the side of keel unit facing indoor;Sound-absorbing cotton is embedded in keel unit.The application solves the problem that, under ultrahigh space, using existing light steel keel partition wall system, wall body may be deformed, even unstable.

Description

Technical Field

[0001] This invention relates to the field of light steel keel partition wall technology, specifically to a high-sided light steel keel soundproof wall suitable for large spaces and its construction method. Background Technology

[0002] With the increasing demands for energy conservation and emission reduction in the construction industry and the development of prefabricated building technology, light steel keel soundproof walls, with their lightweight, high efficiency, environmental friendliness, sound insulation, heat insulation, and fire resistance, are widely used in residential, office, and stadium buildings, further promoting their market application. In the future, the development of light steel keel soundproof walls will place greater emphasis on technological innovation and sustainability.

[0003] In building types that require large-area soundproof walls, such as large exhibition halls and conference venues, the building height is usually high, with some walls reaching 17.7m in height. The proportion of tall walls is large, and the existing light steel keel partition wall system has the problem that the conventional light steel keel is not strong enough to resist lateral forces in ultra-high cases, and the wall may deform or even become unstable. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, a lightweight steel keel soundproof wall suitable for large spaces and its construction method are provided to solve the problem that the existing lightweight steel keel partition wall system may deform or even become unstable in ultra-high spaces.

[0005] To achieve the above objectives, a high-profile lightweight steel keel soundproof wall suitable for large spaces is provided, comprising: The supporting frame includes structural columns, structural beams, and multiple keel units. The structural columns are supported between the floor slab and the steel structural beams. The structural columns are located between two adjacent steel structural columns. The structural beams connect the structural columns and the steel structural columns. The structural columns, structural beams, steel structural columns, and steel structural beams enclose multiple frame openings. Each frame opening is equipped with multiple keel units spaced apart along the axial direction of the frame opening. Each keel unit includes multiple vertical keels and through keels. The vertical keels are erected within the frame openings, and the through keels are connected to the multiple vertical keels. A protective grille is installed on the outside of the supporting frame, and a protective panel is laid on the inside of the protective grille; The sound insulation panel is laid on the indoor-facing side of the keel unit; Sound-absorbing cotton is embedded in the keel unit.

[0006] Furthermore, the number of structural beams is multiple, and the multiple structural beams are arranged at intervals along the vertical direction.

[0007] Furthermore, the spacing between two adjacent structural beams is 6m.

[0008] Furthermore, the structural column is connected to the steel structure beam via angle brackets, and both ends of the structural beam are connected to the steel structure column and the structural column via angle brackets, respectively.

[0009] Furthermore, the enclosure panel and the sound insulation panel are made of cement fiberboard.

[0010] Furthermore, the sound-absorbing cotton is rock wool.

[0011] Furthermore, each frame opening is equipped with three keel units.

[0012] This invention provides a construction method for ultra-high edge-mounted light steel keel sound insulation walls suitable for large spaces, comprising the following steps: The protective grille is installed from the indoor side between the outer edge of the steel structure beam and the outer edge of the floor slab. A protective panel is laid on the inner side of the protective grille; Structural columns are installed between the floor slab and the steel structure beam, such that the structural columns are positioned between two adjacent steel structure columns and abut against the enclosure panel; The structural beam is connected between the structural column and the steel structure column, so that the structural column, the structural beam, the steel structure column and the steel structure beam enclose and form multiple frame openings; Multiple keel units are installed sequentially from the outside to the inside within each of the frame openings. The multiple keel units are spaced apart along the axial direction of the frame openings. After each keel unit is installed, sound-absorbing cotton is embedded in the installed keel unit, and a sound insulation board is laid on the side of the installed keel unit facing the inside.

[0013] The beneficial effects of this invention are as follows: The ultra-high, edge-mounted light steel keel soundproof wall, suitable for large spaces, utilizes structural columns and beams to form multiple frame openings with existing steel structural columns and beams. Within each frame opening, multiple keel units are spaced axially, constructing a composite support framework system of "steel frame + light steel keel." The structural columns are supported between the floor slab and the steel structural beams, while the structural beams effectively enhance the overall rigidity and lateral force resistance of the framework. This system can adapt to the requirements of ultra-high, large-space walls with a maximum height of approximately 17m and a maximum span of approximately 80m, overcoming the technical difficulties of conventional light steel keels in ultra-high situations where their own rigidity and strength are insufficient to resist lateral forces, leading to wall deformation or even instability. Compared to the traditional method of simply adding square steel to the light steel keel framework for reinforcement, the structure of this invention is more rational, avoiding problems such as complex framework structures, increased construction costs, and extended construction periods. Attached Figure Description

[0014] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a structural schematic diagram of an ultra-high edge-mounted light steel keel soundproof wall suitable for large spaces, according to an embodiment of the present invention.

[0015] Figure 2 This is a schematic diagram of the support frame according to an embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of the keel unit according to an embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of the connection node between the support frame and the steel structure beam in an embodiment of the present invention.

[0018] Figure 5 This is a structural schematic diagram of the connection node between the support frame and the steel structure column in an embodiment of the present invention.

[0019] Figure 6 This is a schematic diagram illustrating the construction sequence of an ultra-high edge-mounted light steel keel soundproof wall suitable for large spaces, according to an embodiment of the present invention.

[0020] Figure label: Support frame 1, structural column 11, structural beam 12, keel unit 13, vertical keel 131, through keel 132, horizontal keel 133; 2. Protective grille; 21. Enclosure panel; Sound insulation panel 3; 4 steel structure columns; 5 steel structure beams; Floor 6. Detailed Implementation

[0021] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] Reference Figures 1 to 6 As shown, the present invention provides an ultra-high edge light steel keel soundproof wall suitable for large spaces, including: a supporting frame 1, a protective grille 2, a sound insulation board 3, and sound-absorbing cotton.

[0024] In this embodiment, the supporting frame 1 includes structural columns 11, structural beams 12, and multiple keel units 13.

[0025] In this invention, the ultra-high edge-mounted light steel keel soundproof wall, suitable for large spaces, is installed at the edge of a high-altitude area. The structural column 11 is supported between the floor slab 6 and the steel structural beam 5. (See reference...) Figure 4 and Figure 5 The floor slabs and steel structural beams are connected by steel structural columns. These columns are the original structural columns of the building and are made of square steel. Multiple steel structural columns are spaced apart along the circumferential direction of the building structure. The steel structural beams are I-beams.

[0026] A structural column 11 is positioned between two adjacent steel structural columns 4. A structural beam 12 connects the structural column 11 and the steel structural column 4. The structural column 11, structural beam 12, steel structural column 4, and steel structural beam 5 enclose multiple frame openings. Multiple keel units 13 are installed within each frame opening. The multiple keel units 13 are spaced apart along the axial direction of the frame opening. In this embodiment, three keel units 13 are provided within each frame opening.

[0027] In this embodiment, there are multiple structural beams 12. These multiple structural beams 12 are spaced apart vertically. Specifically, the distance between two adjacent structural beams 12 is 6m.

[0028] Structural column 11 is connected to steel structural beam 5 via angle brackets. Both ends of structural beam 12 are connected to steel structural column 4 and structural column 11 via angle brackets, respectively.

[0029] The keel unit 13 includes vertical keels 131 and through keels 132. In some embodiments, the keel unit is further configured with horizontal keels 133. The vertical keels 131 are erected within the frame opening. The through keels 132 are connected to a plurality of vertical keels 131.

[0030] In this embodiment, the vertical keel is a channel steel. The vertical keel has horizontally oriented through holes. A through-core keel passes through the through holes of multiple vertical keels. The upper end of the vertical keel is connected to a steel structural beam or structural beam. The lower end of the vertical keel is connected to a structural beam or floor slab. Both ends of the through-core keel are connected to structural columns or steel structural columns.

[0031] The protective grille 2 is installed on the outside of the supporting frame 1. The inner side of the protective grille 2 is covered with a protective panel 21.

[0032] The protective grating is constructed using square steel. It consists of a structural frame and multiple grating strips. The structural frame is formed by four square steel bars connected end-to-end. The grating strips are connected between opposite square steel bars. Multiple grating strips are spaced apart along the length of the square steel bars. The grating strips include horizontally arranged strips and vertically arranged strips.

[0033] In this embodiment, the enclosure panel 21 is made of cement fiberboard. Specifically, the enclosure panel comprises double-layer cement fiberboard. The enclosure panel is installed on the protective grid with staggered joints, followed by grouting and sealing treatment.

[0034] Combination Figures 4 to 6 As shown, a sound insulation board 3 is laid on the indoor-facing side of the keel unit 13. The sound insulation board 3 is made of cement fiberboard. Specifically, the sound-absorbing board is a double-layer cement fiberboard.

[0035] Sound-absorbing cotton is embedded in the keel unit 13.

[0036] As a preferred implementation method, rock wool is used for sound absorption. The voids within the keel unit are 100 kg / m². 3 Rock wool filling.

[0037] This invention provides a construction method for ultra-high edge-mounted light steel keel sound insulation walls suitable for large spaces. (See reference...) Figure 6 The direction indicated by the thick black arrow indicates the specific direction of the construction method of the ultra-high edge light steel keel sound insulation wall applicable to large spaces in this invention, that is, the entire construction is carried out on the indoor side, and the specific construction direction is from the outdoor side to the indoor side.

[0038] The specific construction method of the present invention for ultra-high edge light steel keel sound insulation walls applicable to large spaces includes the following steps: S1. Install the protective grille 2 from the indoor side between the outer edge of the steel structure beam 5 and the outer edge of the floor slab 6.

[0039] (1) Construction preparation: Clean up the construction site to ensure that the working surface is flat and free of debris. Check the outer edge position lines of steel structure beam 5 and floor slab 6 to confirm that the installation benchmark is correct.

[0040] (2) Laying out and positioning: According to the design drawings, the installation position line of the protective grid 2 is marked between the outer edge of the steel structure beam 5 and the outer edge of the floor slab 6 to ensure that the grid is installed in an accurate position.

[0041] (3) Installation of protective grid: The protective grid is constructed using square steel. The structural frame (consisting of four square steel bars connected end to end) is installed between the outer edge of the steel structure beam and the outer edge of the floor slab, and fixed by welding or bolting. After the structural frame is installed, grid strips are installed between two opposite square steel bars. The horizontal and vertical grid strips are spaced at the designed intervals along the length of the square steel bars to form a grid-like protective structure. All connection nodes should be firm and reliable.

[0042] (4) Quality inspection: After installation, check the verticality, flatness and connection firmness of the protective grille. The deviation should be within the allowable range of the specification.

[0043] S2. Lay a protective panel 21 on the inner side of the protective grille 2.

[0044] (1) Material preparation: Cement fiberboard is used for the enclosure panel 21. After the materials arrive on site, their specifications, models and performance should be inspected to ensure they meet the design requirements.

[0045] (2) Installation of enclosure panels: Enclosure panels 21 are installed on the inner side of the protective grid 2. The enclosure panels are made of double-layer cement fiberboard. The two layers of panels should be installed with staggered joints, and the joints should be filled and sealed.

[0046] (3) Fixing method: The enclosure panel is fixed to the square steel of the protective grid by self-tapping screws or rivets. The screw spacing should meet the design requirements to ensure that the panel is firmly fixed and flat.

[0047] (4) Quality inspection: Check whether the enclosure panels are installed flat, whether the joints are tight, and whether the fixing is firm.

[0048] S3. Install structural columns 11 between floor slab 6 and steel structure beam 5, so that structural columns 11 are set between two adjacent steel structure columns 4, and structural columns 11 abut against the enclosure plate 21.

[0049] (1) Positioning of structural columns: According to the design drawings, determine the installation position of structural columns 11 between the floor slab 6 and the steel beam 5 between two adjacent steel structural columns 4.

[0050] (2) Installation of structural columns: The structural column 11 is erected between the floor slab 6 and the steel structure beam 5, with one side of the structural column 11 abutting against the laid enclosure 21. The upper end of the structural column 11 is connected to the steel structure beam 5 by angle brackets, and the lower end is fixed to the floor slab 6.

[0051] (3) Verticality control: During the installation process, a straightedge or plumb line should be used to control the verticality of the structural column 11 to ensure that it is installed vertically.

[0052] (4) Secure connection: The connection between the corner bracket and the steel structure beam and structural column shall be secured with bolts, and the connection nodes shall be secure and reliable.

[0053] S4. Connect the structural beam 12 between the structural column 11 and the steel structure column 4, so that the structural column 11, structural beam 12, steel structure column 4 and steel structure beam 5 enclose and form multiple frame openings.

[0054] (1) Positioning of structural beams: Determine the installation elevation of each structural beam 12 according to the design drawings. Multiple structural beams 12 are set at intervals in the vertical direction, and the distance between two adjacent structural beams 12 is 6m.

[0055] (2) Installation of structural beam: Connect both ends of structural beam 12 to steel structure column 4 and structural column 11 respectively by angle brackets. Structural beam 12 should be installed horizontally.

[0056] (3) Formation of frame openings: As the structural beams 12 are installed one by one, the structural columns 11, structural beams 12, steel structural columns 4 and steel structural beams 5 together form multiple frame openings. After each structural beam is installed, its elevation and levelness should be checked.

[0057] (4) Node treatment: All corner bracket connection nodes should be fastened with bolts to ensure that the connection between the structural beam and the structural column and steel structure column is firm.

[0058] S5. Install multiple keel units 13 sequentially from the outside to the inside in each frame opening. The multiple keel units 13 are spaced apart along the axial direction of the frame opening. After each keel unit is installed, sound-absorbing cotton is embedded in the installed keel unit 13 and sound insulation board 3 is laid on the side of the installed keel unit 13 facing the inside.

[0059] (1) Installation sequence of keel units: Multiple keel units 13 are installed sequentially from the outside to the inside of each frame opening. Three keel units 13 are provided in each frame opening. Each keel unit 13 includes multiple vertical keels 131 and through keels 132. The vertical keels 131 are erected in the frame opening, and the through keels 132 are connected to the multiple vertical keels 131.

[0060] (2) Installation of vertical keel: The upper end of the vertical keel 131 is connected to the steel structure beam 5 or the structural beam 12, and the lower end is connected to the structural beam 12 or the floor slab 6. The spacing of the vertical keel 131 should meet the design requirements. During installation, ensure that the keel is vertical and flat.

[0061] (3) Installation of through-core keel: The vertical keel 131 has horizontal through holes, and the through-core keel 132 is inserted through the through holes of multiple vertical keels. The two ends of the through-core keel 132 are connected to the structural column 11 or the steel structure column 4. The connection between the through-core keel and the vertical keel should be firm.

[0062] (4) Sound-absorbing cotton filling: After each keel unit is installed, sound-absorbing cotton is immediately embedded in the keel unit 13. The sound-absorbing cotton is made of rock wool with a density of 100 kg / m³. 3 The sound-absorbing cotton should be laid evenly without gaps and tightly fitted to the keel; the filling should be laid neatly to ensure that the filling layer thickness is uniform; before installation, ensure that the rock wool material is dry and moisture-proof.

[0063] (5) Sound insulation board installation: After the sound-absorbing cotton is filled, the sound insulation board 3 is laid on the indoor-facing side of the installed keel unit 13. The sound insulation board 3 is made of cement fiberboard and is a double-layer cement fiberboard. The sound insulation board 3 should be fixed to the keel unit 13 with self-tapping screws. The two layers of boards should be installed with staggered joints, and the joints should be filled and sealed.

[0064] (6) Construction in a cyclical manner: Repeat steps (1) to (5) above to complete the installation of each keel unit in each frame opening, the filling of sound-absorbing cotton and the laying of sound insulation board in sequence until all construction is completed.

[0065] (7) Quality acceptance: After all construction is completed, quality acceptance shall be carried out in accordance with the standards to check the firmness of the keel installation, the density of the sound-absorbing cotton filling, the flatness of the sound insulation board and the quality of the joint treatment, etc.

[0066] This invention relates to an ultra-high edge-supported light steel keel soundproof wall suitable for large spaces. It can be applied to walls with a maximum height of approximately 17.7m and a maximum span of approximately 80.2m, primarily suitable for large open spaces. The frame system of this invention's ultra-high edge-supported light steel keel soundproof wall is compatible with tall walls, resulting in good overall stability. Furthermore, the unidirectional installation of this invention significantly improves efficiency and is beneficial for project safety, quality, schedule, and cost control.

[0067] This invention relates to a high-rise, lightweight steel keel soundproof wall suitable for large spaces. It utilizes structural columns and beams that, together with existing steel columns and beams, form multiple frame openings. Within each frame opening, multiple keel units are spaced axially, creating a composite support framework system of "steel frame + lightweight steel keel." The structural columns are supported between the floor slab and the steel beams, while the structural beams effectively enhance the overall rigidity and lateral force resistance of the framework. This system can accommodate ultra-high, large-space walls with a maximum height of approximately 17.7m and a maximum span of approximately 80.2m, overcoming the technical challenges of conventional lightweight steel keels lacking sufficient rigidity and strength to resist lateral forces in ultra-high situations, leading to wall deformation and even instability. Compared to the traditional method of simply adding square steel to the lightweight steel keel framework, this invention offers a more rational structure, avoiding problems such as complex framework structures, increased construction costs, and extended construction periods.

[0068] This invention relates to a multi-layered composite sound insulation structure for ultra-high edge lightweight steel keel soundproof walls suitable for large spaces, employing a combination of "protective grille + enclosure panel + multiple keel units + sound-absorbing cotton + sound insulation board". The sound-absorbing cotton uses 100kg / m² of material. 3 High-density rock wool is embedded within the keel unit, working synergistically with the double-layer cement fiberboard cladding and sound insulation panels to form a complete sound insulation path of "sound absorption—sound insulation—vibration reduction." The rock wool filling the keel cavity effectively absorbs airborne noise, reducing internal wall resonance. Simultaneously, the frictional resistance between the rock wool and the cladding panels hinders wall bending vibration, significantly improving the overall sound insulation performance of the wall. Both the cladding and sound insulation panels are installed with staggered joints and sealed to further ensure the wall's airtightness and sound insulation effect.

[0069] The construction method of this invention for ultra-high edge light steel keel soundproof walls in large spaces is carried out entirely from the indoor side. It begins with the installation of protective grilles and the laying of enclosure panels, followed by the installation of structural columns and beams, and finally, the installation of keel units one by one from the outside in. The construction flow is clear and the procedures are reasonable. After each step is completed, sound-absorbing cotton is immediately filled and sound insulation boards are laid, achieving streamlined operation and avoiding interference from overlapping construction. Compared to traditional partition wall construction methods that require work on both sides or the erection of external scaffolding, this invention significantly improves construction efficiency and shortens the construction cycle. At the same time, the unit-by-unit installation method facilitates quality control and process acceptance, helping to ensure the overall construction quality of the wall.

[0070] This invention provides a construction method for ultra-high edge-protected light steel keel soundproof walls applicable to large spaces, fully utilizing protective grilles as a safety feature. The protective grilles are installed between the outer edges of the steel structure beams and the outer edges of the floor slabs, serving both as a component of the wall structure and as an edge protection barrier during construction. Construction workers operate entirely from the indoor side, eliminating the need for suspended work on the outer edge, significantly reducing the safety risks of high-altitude edge work and greatly benefiting project safety management.

[0071] This invention relates to a lightweight steel keel soundproof wall suitable for large spaces with ultra-high edge coverage. Using lightweight steel keel and cement fiberboard as the main materials, it offers the advantage of lighter weight compared to traditional brick or concrete walls, effectively reducing the load on the building structure. Simultaneously, the lightweight steel keel partition wall system allows for integrated construction of walls, pipelines, and decorations, reducing on-site chiseling and grooving work and minimizing dust pollution. The organic integration of structural columns and beams with the existing steel structure system fully utilizes existing structural components, reducing additional steel consumption and offering excellent economic and environmental benefits. Furthermore, the rock wool filling also provides insulation and fireproofing, giving the wall multiple functionalities.

[0072] The ultra-high edge light steel keel soundproof wall of the present invention is suitable for large spaces, especially for ultra-high edge soundproof wall projects in large-space buildings with high floor height and large span, such as large exhibition halls, conference venues, and airport terminals. It can also be extended to other light steel keel partition wall projects with high requirements for sound insulation, fire prevention and heat preservation, and has good prospects for promotion and application.

[0073] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A high-sided lightweight steel keel soundproof wall suitable for large spaces, characterized in that, include: The supporting frame includes structural columns, structural beams, and multiple keel units. The structural columns are supported between the floor slab and the steel structural beams. The structural columns are located between two adjacent steel structural columns. The structural beams connect the structural columns and the steel structural columns. The structural columns, structural beams, steel structural columns, and steel structural beams enclose multiple frame openings. Each frame opening is equipped with multiple keel units spaced apart along the axial direction of the frame opening. Each keel unit includes multiple vertical keels and through keels. The vertical keels are erected within the frame openings, and the through keels are connected to the multiple vertical keels. A protective grille is installed on the outside of the supporting frame, and a protective panel is laid on the inside of the protective grille; The sound insulation panel is laid on the indoor-facing side of the keel unit; Sound-absorbing cotton is embedded in the keel unit.

2. The ultra-high edge-mounted light steel keel soundproof wall suitable for large spaces according to claim 1, characterized in that, The number of structural beams is multiple, and the multiple structural beams are arranged at intervals along the vertical direction.

3. The ultra-high edge-mounted light steel keel soundproof wall suitable for large spaces according to claim 2, characterized in that, The distance between two adjacent structural beams is 6m.

4. The ultra-high edge-mounted light steel keel soundproof wall suitable for large spaces according to claim 1, characterized in that, The structural column is connected to the steel structure beam via angle brackets, and both ends of the structural beam are connected to the steel structure column and the structural column via angle brackets, respectively.

5. The ultra-high edge-mounted light steel keel soundproof wall suitable for large spaces according to claim 1, characterized in that, The enclosure panel and the sound insulation panel are made of cement fiberboard.

6. The ultra-high edge-mounted light steel keel soundproof wall suitable for large spaces according to claim 1, characterized in that, The sound-absorbing cotton is rock wool.

7. The ultra-high edge-mounted light steel keel soundproof wall suitable for large spaces according to claim 1, characterized in that, Each frame opening contains three keel units.

8. A construction method for an ultra-high light steel keel soundproof wall suitable for large spaces, as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The protective grille is installed from the indoor side between the outer edge of the steel structure beam and the outer edge of the floor slab. A protective panel is laid on the inner side of the protective grille; Structural columns are installed between the floor slab and the steel structure beam, such that the structural columns are positioned between two adjacent steel structure columns and abut against the enclosure panel; The structural beam is connected between the structural column and the steel structure column, so that the structural column, the structural beam, the steel structure column and the steel structure beam enclose and form multiple frame openings; Multiple keel units are installed sequentially from the outside to the inside within each of the frame openings. The multiple keel units are spaced apart along the axial direction of the frame openings. After each keel unit is installed, sound-absorbing cotton is embedded in the installed keel unit, and a sound insulation board is laid on the side of the installed keel unit facing the inside.

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