Ultra-lightweight median barrier installation structure for soundproof tunnels

Abstract

The present invention provides an installation structure for an ultra-lightweight central divider wall in a soundproof tunnel that minimizes the load exerted by the roof frame of the soundproof tunnel on the substructure, thereby preventing problems with the structural safety of the existing substructure. According to a suitable embodiment of the present invention, in a structure for installing an ultra-lightweight central divider wall on the roof frame of a soundproof tunnel to block noise generated from the substructure, so as to minimize the load acting on the lower central foundation, the structure comprises a central divider wall vertical member whose upper end is fixed to the inner center of the roof frame along the longitudinal direction of the soundproof tunnel, and a flame spread prevention barrier installed in the inner area of ​​the central divider wall vertical member to block the propagation of flames and toxic gases generated inside the soundproof tunnel to adjacent lanes, wherein the lower end of the central divider wall vertical member is installed at a certain spacing from the lower central foundation so that the load of the central divider wall vertical member does not act on the lower central foundation.

Description

Technology Field

[0001] The present invention relates to a structure for installing a central partition wall of a soundproof tunnel, and more specifically, to an ultra-lightweight structure for installing a central partition wall of a soundproof tunnel that minimizes the load-bearing effect of the central partition wall of the soundproof tunnel on the substructure, thereby preventing problems with the structural safety of the existing substructure. Background Technology

[0002] Soundproof tunnels installed above existing overpasses typically consist of a standard roof frame and side wall structures. While this design is effective in reducing noise, it fails to prevent the spread of flames and toxic gases generated inside the tunnel from the center. Consequently, in the event of a fire, smoke and gases rapidly propagate to the adjacent lanes.

[0003] Conventionally, to block the spread of flames and toxic gases, median barriers within soundproof tunnels were constructed by directly fixing them to the road foundation (central foundation). In this case, the self-weight and impact loads of the median barrier are transferred entirely to the existing bridge foundation, raising concerns about reduced structural safety. Particularly in the case of aging elevated roads, the increased load necessitates structural reinforcement. Meanwhile, existing soundproof tunnels and median barriers are primarily installed using rigid fixed structures. Consequently, vibrations from vehicle traffic are transmitted directly to the structure, leading to cracks and deformation that increase maintenance costs. Furthermore, within conventional soundproof tunnels, the lane separation function exists only at the level of simple sound barriers. Therefore, there is a lack of technology for applying barriers or non-combustible materials to separate lanes in the event of a fire inside the tunnel. In such cases, the risk of secondary accidents increases as a large-scale fire spreads to adjacent lanes. Therefore, a structural construction method is required that can block the propagation of flames and toxic gases between lanes in both directions in the event of a fire inside the soundproof tunnel, and prevent vibrations from the road structure from being transmitted to the soundproof tunnel.

[0004] As the background technology for the present invention, Korean Registered Patent No. 10-2612545 (Patent Document 1) proposes a "fire spread blocking system for blocking fire spread in soundproof tunnels." This is designed to be installed at appropriate intervals depending on the structure and installation environment of existing or newly installed soundproof tunnels, thereby effectively blocking the spread of fire and exhausting toxic gases generated within the soundproof tunnel. Another technology as the background technology for the present invention is Korean Published Patent No. 10-2025-0070552 (Patent Document 2) proposes a "soundproof tunnel equipped with a fire extinguishing and smoke exhaust device." This is designed to prevent the spread of fire and smoke by rapidly sucking in and exhausting flames and smoke from a location close to the fire point when a fire occurs within the soundproof tunnel, while simultaneously selectively and intensively spraying fire extinguishing liquid at the fire point. However, the aforementioned background technologies have the disadvantage that flames and toxic gases generated by a fire in one lane can spread to the other lane because a central wall is not installed inside the soundproof tunnel. Prior art literature

[0005] Korean Registered Patent No. 10-2612545 Korean Published Patent No. 10-2025-0070552 The problem to be solved

[0006] The purpose of the present invention is to provide an ultra-lightweight central partition wall installation structure for a soundproof tunnel that minimizes the load influence of the central partition wall on the substructure, thereby preventing problems with the structural safety of the existing substructure. means of solving the problem

[0007] According to a suitable embodiment of the present invention, in a structure for installing an ultra-lightweight central divider on a roof frame of a soundproof tunnel to block noise generated from a substructure so as to minimize the load acting on the lower central foundation, the structure comprises a central divider vertical member whose upper end is fixed to the inner center of the roof frame along the longitudinal direction of the soundproof tunnel, and a flame spread prevention barrier installed in the inner area of ​​the central divider vertical member to block the propagation of flames and toxic gases generated inside the soundproof tunnel to an adjacent lane, wherein the lower end of the central divider vertical member is installed at a certain spacing from the lower central foundation so as not to apply the load of the central divider vertical member to the lower central foundation.

[0008] In addition, it is characterized by installing a lower horizontal member of the central partition wall at the bottom of the vertical member of the central partition wall on both sides located in one or two spans.

[0009] In addition, the flame spread prevention barrier is installed by a membrane fixing bar having a cut-out slot hole, which is fixedly installed on the inner surface of the longitudinal runner beam on the roof frame side, the inner surface of the vertical members of the central partition walls on both sides, and the inner surface of the lower horizontal members of the central partition walls, wherein the flame spread prevention barrier is characterized by being made of a semi-noncombustible membrane material that has been treated with a noncombustible coating on a woven fabric.

[0010] In addition, the flame spread prevention barrier is characterized by being composed of an L-shaped angle bolted to each of the vertical members of the central separation wall on both sides, and a corrugated soundproofing plate made of corrugated steel plate and installed on the vertical members of the central separation wall on both sides through the L-shaped angle.

[0011] In addition, to prevent vertical and horizontal vibrations of the substructure from being transmitted to the vertical members of the central separation wall, the lower end of the central separation wall vertical member is movably connected to the upper vertical slot of the vertical slot connecting plate through an upper pin connection, and the lower end of the vertical slot connecting plate is connected through a lower pin movably inserted into the horizontal slot connecting plate installed on the central foundation.

[0012] In addition, it is characterized by the additional installation of a Teflon plate that absorbs vibrations of the substructure between the lower side of the central partition vertical member and the vertical slot connecting plate.

[0013] In addition, to prevent vertical and horizontal vibrations of the substructure from being transmitted to the vertical members of the central separation wall, the lower ends of the vertical members of the central separation wall are connected to the lower central foundation via anchor bolts with a spacing, and a cushioning pad is installed between the lower ends of the vertical members of the central separation wall and the lower central foundation to absorb the vertical and horizontal vibrations of the substructure.

[0014] In addition, to prevent vertical and horizontal vibrations of the substructure from being transmitted to the vertical members of the central separation wall, a spring support plate is additionally installed at a spaced interval at the bottom of the central separation wall vertical members, anchor bolts are inserted into the spring support plates and connected and fixed to the lower central foundation, and one or more cushioning springs are inserted into the anchor bolts to absorb vertical vibrations of the substructure.

[0015] In addition, the buffer spring is characterized by being installed between the spring support plate and the nut fastened to the anchor bolt.

[0016] In addition, the buffer spring is characterized by being installed between the spring support plate and the lower central foundation.

[0017] In addition, the buffer springs are characterized by being installed between the spring support plate and the nut fastened to the anchor bolt, and between the spring support plate and the lower central foundation, respectively.

[0018] In addition, the lower horizontal member of the central partition wall is characterized by the additional installation of a gap covering plate made of non-combustible material or steel plate to fill the gap created between it and the lower central foundation. Effects of the invention

[0019] According to the present invention, the vertical members of the central partition wall are fixed to the roof frame and installed with a gap from the lower central foundation, thereby preventing the load from being directly transmitted to the substructure. Additionally, if necessary, pin joints, slot structures, springs, cushioning pads, etc., can be inserted at the connection point with the lower section to absorb only vibrations. Therefore, the additional load burden on existing elevated road structures can be minimized, structural stability issues caused by the additional installation of soundproof tunnels can be prevented, and the need for reinforcing the existing foundation is significantly reduced as the load is distributed through the upper roof frame piers.

[0020] In addition, by installing flame-spreading barriers inside the median barrier in the form of semi-noncombustible membranes or steel plate-type soundproofing panels (e.g., PosMAC), the spread of flames, smoke, and toxic gases to adjacent lanes in the event of an accident inside the tunnel can be blocked, thereby reducing the risk of large-scale fires and suffocation accidents spreading and minimizing casualties by ensuring evacuation safety within the structure.

[0021] In addition, by applying various vibration absorption mechanisms between the vertical members of the median barrier and the foundation, damage to the median barrier caused by external forces such as driving vibrations on the elevated road, wind loads, and earthquakes is prevented; deformation of the soundproofing materials and structures inside the soundproof tunnel is minimized; and maintenance costs are reduced while durability is improved.

[0022] In addition, standard components such as H-shaped steel and circular steel pipes are utilized for the vertical members of the partition walls, and on-site assembly and disassembly are possible using flange and bolt fastening methods. Furthermore, both the barrier materials (membrane type and plate type) are designed with a fixed structure to facilitate easy replacement, thereby improving construction speed and ensuring operational efficiency by simplifying future replacement and maintenance work. Brief explanation of the drawing

[0023] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description thereof; therefore, the present invention should not be interpreted as being limited only to the matters described in the attached drawings. FIG. 1 is an example of the installation of a soundproof tunnel according to an embodiment of the present invention. FIG. 2a is a side view of the ultra-lightweight central divider installed in FIG. 1. FIG. 2b is a plan view of FIG. 2a. FIG. 3 is a cross-sectional view taken along line AA of FIG. 2b. FIG. 4 is an example diagram showing a central partition vertical member installed every two spans in accordance with the present invention. FIG. 5a is an example diagram showing an ultra-lightweight central partition wall constructed on a roof frame constructed with circular steel pipes according to the present invention. FIG. 5b is a side view of FIG. 5a. FIG. 6a is an example diagram showing a corrugated soundproofing panel installed on a vertical member of a central partition wall to which the present invention is applied. FIG. 6b is a cross-sectional view taken along line BB of FIG. 6a. FIG. 7 is a cross-sectional view taken along the CC line of FIG. 6a. Fig. 8a is an enlarged view of the lumbar region of Fig. 7. FIG. 8b is a side view of FIG. 8a. FIG. 9 is an exemplary illustration of vibration prevention according to another embodiment of the present invention. FIG. 10 is an exemplary illustration of vibration prevention according to another embodiment of the present invention. FIGS. 11a to 11c are various vibration prevention examples according to another embodiment of the present invention. Specific details for implementing the invention

[0024] The present invention will be described in detail below with reference to embodiments shown in the attached drawings, but the presented embodiments are exemplary for a clear understanding of the present invention and the present invention is not limited thereto.

[0025] As shown in FIG. 1, the soundproof tunnel (20) to which the present invention is applied is installed to block noise generated from a substructure (existing elevated road) (10). An ultra-lightweight central divider wall (30) is installed on the roof frame (22) of the soundproof tunnel (20) so as to minimize the load acting on the lower central foundation (12). Here, the ultra-lightweight central divider wall (30) is installed to block the propagation of flames and toxic gases generated inside the soundproof tunnel (20) to adjacent lanes. The roof frame (22) includes a transverse roof member (222) and a longitudinal runner beam (224). The transverse roof member (222) can be made of an H-shaped steel or a circular steel pipe.

[0026] First, as shown in FIGS. 2 and 4, a central partition wall vertical member (32) is installed along the longitudinal direction of the soundproof tunnel (20) at the center of the interior of the roof frame (22) for every one or two spans. The central partition wall vertical member (32) is made of H-shaped steel, but is not limited to such a cross-section. The central partition wall vertical member (32) can be installed and fixed to the transverse roof member (222) by welding or bolting. For example, the central partition wall vertical member (32) may be installed by being fixed to the transverse roof member (222) by fastening a bolt and nut, with a flange provided on the upper part.

[0027] Next, a flame spread prevention barrier (34) is installed in the inner area of ​​the central divider vertical member (32). The flame spread prevention barrier (34) substantially blocks the propagation of flames and toxic gases generated inside the soundproof tunnel (20) to adjacent lanes.

[0028] At this time, in order to prevent the load of the central separation wall vertical member (32) from acting on the lower central foundation (12), the lower fixed end of the central separation wall vertical member (32) is installed at a constant spacing (G) from the lower central foundation (12) during the installation process of the central separation wall vertical member (32).

[0029] Therefore, the load acting vertically at the center of the roof frame (22) in the soundproof tunnel (20) does not reach the lower central foundation (12) of the substructure (10) due to the spacing (G). As a result, no problem occurs with the structural safety of the existing substructure (e.g., bridge, bridge, etc.) (10). In this case, as shown in FIG. 1, the soundproof tunnel (20) can ensure that the load is fully transferred only to separate bridge piers (5) dedicated to the soundproof tunnel installed on both sides of the existing substructure (10).

[0030] Here, in order to ensure stable installation of the flame spread prevention barrier (34), a central partition wall lower horizontal member (36) may be further installed at the bottom of the vertical members (32 and 32) of the central partition walls located in one or two spans. The central partition wall lower horizontal member (36) is made of H-shaped steel, but is not limited to such a cross-section.

[0031] In one form, the flame spread prevention barrier (34) can be installed by a membrane fixing bar (42) fixed to the inner surface of the longitudinal runner beam (224) on the roof frame (22) side (see FIG. 3), the inner surface of the vertical members (32 and 32) of the central partition wall on both sides, and the inner surface of the lower horizontal member (36) of the central partition wall. The membrane fixing bar (42) has a slot hole (422) cut into its inner surface. At this time, it is preferable that the flame spread prevention barrier (34) be made of a semi-noncombustible membrane material that has been treated with a noncombustible coating on a woven fabric. Accordingly, the membrane fixing bar (42) can be installed to be connected to and receive tension from the flame spread prevention barrier (34) made of the semi-noncombustible membrane material.

[0032] Another type of flame spread prevention barrier (34) may be composed of an L-shaped angle (342) that is bolted to each of the vertical members (32, 32) of the central partition walls on both sides as shown in FIGS. 6a to 6c, and a corrugated soundproofing plate (344) made of a corrugated steel plate and installed on the vertical members (32, 32) of the central partition walls on both sides through the L-shaped angle (342). For example, the corrugated soundproofing plate (344) may be made of a high-corrosion-resistant alloy plated steel plate (product name 'PosMAC').

[0033] Meanwhile, as shown in FIGS. 7 and 8, in order to prevent vibrations of the substructure (10) from being transmitted to the central separation wall vertical member (32), the lower end of the central separation wall vertical member (32) can be movably connected to the upper vertical slot (35a) of the vertical slot connecting plate (35) through the connection of an upper pin (33) (or bolt), and the lower end of the vertical slot connecting plate (35) can be constructed to be connected through a lower pin (39) (or bolt) that is movably inserted into the horizontal slot connecting plate (37) installed on the central foundation (12).

[0034] Here, as shown in FIG. 9, a Teflon plate (53) that absorbs vibrations of the substructure (10) may be additionally installed between the lower side of the central partition wall vertical member (32) and the vertical slot connecting plate (35). In this case, the Teflon plate (53) blocks direct contact between the central partition wall vertical member (32) and the vertical slot connecting plate (35), thereby reducing surface friction and effectively blocking vibrations transmitted to the central partition wall vertical member (32).

[0035] Of course, as shown in Fig. 10, in order to prevent vibrations of the substructure (10) from being transmitted to the central partition wall vertical member (32), the lower end of the central partition wall vertical member (32) is connected to the lower central foundation (12) through an anchor bolt (52) with a spacing (G), and a cushioning pad (54) that absorbs vibrations of the substructure (10) may be installed between the lower end of the central partition wall vertical member (32) and the lower central foundation (12).

[0036] On the other hand, to prevent vibrations of the substructure (10) from being transmitted to the central partition wall vertical member (32), a spring support plate (332) is additionally installed at the bottom of the central partition wall vertical member (32) with a spacing (G) as shown in FIG. 11, and an anchor bolt (52) is inserted into the spring support plate (332) and connected to the lower central foundation (12), and one or more cushioning springs (56) can be inserted into the anchor bolt (52) to absorb vertical vibrations of the substructure (10).

[0037] Here, as shown in FIG. 11a, the cushioning spring (56) can be installed between the spring support plate (332) and the nut (58) fastened to the anchor bolt (52). In this case, when the lower central foundation (12) descends, the cushioning spring (56) is compressed to absorb vibration.

[0038] In another form, as shown in FIG. 11b, the cushioning spring (56) can be installed between the spring support plate (332) and the lower central foundation (12). In this case, when the lower central foundation (12) rises, the cushioning spring (56) is compressed to absorb vibration.

[0039] In another form, as shown in FIG. 11c, the buffer spring (56) may be installed between the spring support plate (332) and the nut (58) connected to the anchor bolt (52), and between the spring support plate (332) and the lower central foundation (12). In this case, when the lower central foundation (12) descends, the upper buffer spring (56) is compressed, and when the lower central foundation (12) rises, the lower buffer spring (56) is compressed to absorb vibrations.

[0040] Meanwhile, as shown in FIG. 7, a gap cover plate (38) made of a non-combustible material or steel plate may be additionally installed on the lower horizontal member (36) of the central partition wall to fill the gap (G) created between it and the lower central foundation (12). In this case, the gap cover plate (38) can block the spread of flames or the propagation of toxic gases through the gap (G).

[0041] In this way, the central partition vertical member (32) of the present invention is fixed to the roof frame (22) and installed with a gap (G) from the lower central foundation (12), so that the load is not directly transmitted to the lower structure (10). Additionally, if necessary, a pin connection, slot structure, spring, cushioning pad, etc., can be inserted into the connection part with the lower part to absorb only vibrations.

[0042] Therefore, the additional load burden on the existing elevated road structure can be minimized, and structural stability problems caused by the additional installation of the tunnel can be prevented. Since the load is distributed through the upper roof frame piers (5), the need for reinforcing the existing foundation is greatly reduced.

[0043] In addition, a flame spread prevention barrier (34) is installed inside the central partition wall (30) in the form of a semi-noncombustible membrane or a steel plate-type soundproofing panel (e.g., PosMAC), thereby blocking flames, smoke, and toxic gases from spreading to other adjacent lanes when an accident occurs inside the tunnel, thereby reducing the risk of large-scale fire and suffocation accidents spreading and minimizing casualties by ensuring safety of evacuation within the structure.

[0044] In addition, various vibration absorption mechanisms are applied between the vertical member (32) of the central divider and the foundation (12), thereby preventing damage to the central divider caused by external forces such as driving vibrations of the elevated road, wind loads, and earthquakes, minimizing deformation of the barrier material and structure inside the soundproof tunnel, and reducing maintenance costs and improving durability.

[0045] In addition, standard components such as H-shaped steel and circular steel pipes are utilized for the vertical members of the partition walls, and on-site assembly and disassembly are possible using flange and bolt fastening methods. Furthermore, both the barrier materials (membrane type and plate type) are designed with a fixed structure to facilitate easy replacement, thereby improving construction speed and ensuring operational efficiency by simplifying future replacement and maintenance work.

[0046] Although the present invention has been described in detail with reference to the presented embodiments, those skilled in the art may make various modifications and variations without departing from the technical spirit of the present invention by referring to the presented embodiments. The present invention is not limited by such modifications and variations, but is limited only by the claims appended below. Explanation of the symbols

[0047] 10 : Substructure 12 : Lower central foundation 12 : Central foundation 20 : Soundproof tunnel 22 : Roof frame 30 : Ultralight central divider 32 : Central divider vertical member 33 : Upper pin 34 : Flame spread prevention barrier 35 : Vertical slot connecting plate 35a : Vertical elongated hole 36 : Central divider lower horizontal member 37 : Horizontal slot connecting plate 37a : Horizontal elongated hole 38 : Spacing cover plate 39 : Lower pin 42 : Membrane fixing bar 52 : Anchor bolt 53 : Teflon plate 54 : Cushioning pad 56 : Cushioning spring 58 : Nut 224 : Longitudinal runner beam 332 : Spring support plate 342 : L-shaped angle 344 : Corrugated soundproof panel 422 : Slot hole

Claims

Claim 1 A structure for installing an ultra-lightweight central divider (30) in a roof frame (22) of a soundproof tunnel (20) to block noise generated in a substructure (10) so as to minimize the load acting on the lower central foundation (12), comprising: a central divider vertical member (32) whose upper end is fixed to the inner center of the roof frame (22) along the longitudinal direction of the soundproof tunnel (20); and a flame spread prevention barrier (34) installed in the inner area of ​​the central divider vertical member (32) to block the propagation of flames and toxic gases generated inside the soundproof tunnel (20) to an adjacent lane, wherein the lower end of the central divider vertical member (32) is installed with a certain spacing (G) from the lower central foundation (12) so as not to apply the load of the central divider vertical member (32) to the lower central foundation (12). Claim 2 A soundproof tunnel ultra-lightweight central partition wall installation structure characterized by further installing a central partition wall lower horizontal member (36) at the bottom of the vertical members (32 and 32) of both central partition walls in claim 1. Claim 3 In claim 1, the flame spread prevention barrier (34) is installed by a membrane fixing bar (42) having a cut-out slot hole (422) fixedly installed on the inner surface of the longitudinal runner beam (224) on the roof frame (22), the inner surface of the vertical members (32 and 32) of the central separation wall on both sides, and the inner surface of the lower horizontal member (36) of the central separation wall, wherein the flame spread prevention barrier (34) is made of a semi-noncombustible membrane material that has been treated with a noncombustible coating on a woven fabric, characterized in that it is an ultra-lightweight central separation wall installation structure of a soundproof tunnel. Claim 4 In claim 1, the flame spread prevention barrier (34) is characterized by being composed of an L-shaped angle (342) that is bolted to each of the vertical members (32, 32) of the central separation wall on both sides, and a corrugated soundproofing plate (344) made of a corrugated steel plate and installed on the vertical members (32, 32) of the central separation wall on both sides through the L-shaped angle (342); an ultra-lightweight central separation wall installation structure of a soundproof tunnel. Claim 5 In claim 3 or 4, to prevent vertical and horizontal vibrations of the substructure (10) from being transmitted to the central separation wall vertical member (32), the lower end of the central separation wall vertical member (32) is movably connected to the upper vertical slot connecting plate (35) through the connection of an upper pin (33) (or bolt), and the lower end of the vertical slot connecting plate (35) is connected through a lower pin (39) (or bolt) that is movably inserted into the horizontal slot connecting plate (37) installed on the central foundation (12), characterized by an ultra-lightweight central separation wall installation structure for a soundproof tunnel. Claim 6 In claim 5, the ultra-lightweight central partition wall installation structure of a soundproof tunnel is characterized by additionally installing a Teflon plate (53) that absorbs vibrations of the substructure (10) between the lower side of the central partition wall vertical member (32) and the vertical slot connecting plate (35). Claim 7 In claim 2 or 3, the lower end of the central separation wall vertical member (32) is connected to the lower central foundation (12) via an anchor bolt (52) with a spacing (G) to block vertical and horizontal vibrations of the substructure (10) from being transmitted to the central separation wall vertical member (32), and a cushioning pad (54) that absorbs vertical and horizontal vibrations of the substructure (10) is installed between the lower end of the central separation wall vertical member (32) and the lower central foundation (12), characterized by an ultra-lightweight central separation wall installation structure for a soundproof tunnel. Claim 8 In claim 2 or 3, a spring support plate (332) is additionally installed at the bottom of the central separation wall vertical member (32) with a spacing (G) to block vertical and horizontal vibrations of the substructure (10) from being transmitted to the central separation wall vertical member (32), an anchor bolt (52) is inserted into the spring support plate (332) and connected and fixed to the lower central foundation (12), and one or more cushioning springs (56) are inserted into the anchor bolt (52) to absorb vertical vibrations of the substructure (10), characterized in that the ultra-lightweight central separation wall installation structure of a soundproof tunnel. Claim 9 In claim 8, the ultra-lightweight central partition wall installation structure of a soundproof tunnel is characterized in that the cushioning spring (56) is installed between the spring support plate (332) and the nut (58) fastened to the anchor bolt (52). Claim 10 In claim 8, the ultra-lightweight central partition wall installation structure of a soundproof tunnel is characterized in that the cushioning spring (56) is installed between the spring support plate (332) and the lower central foundation (12). Claim 11 In claim 8, the ultra-lightweight central partition wall installation structure of a soundproof tunnel is characterized in that the cushioning spring (56) is installed between the spring support plate (332) and the nut (58) fastened to the anchor bolt (52), and between the spring support plate (332) and the lower central foundation (12). Claim 12 In claim 2, the ultra-lightweight central partition wall installation structure of a soundproof tunnel is characterized by additionally installing a gap covering plate (38) made of non-combustible material or steel plate to fill the gap (G) created between the lower horizontal member (36) of the central partition wall and the lower central foundation (12).

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