Novel tunnel preliminary bracing structure

Abstract

The utility model provides a novel tunnel preliminary bracing structure which comprises an arch wall preliminary bracing, a first side wall preliminary bracing, a second side wall preliminary bracing, an inverted arch preliminary bracing and a bias retaining wall, the first side wall preliminary bracing is connected below the arch wall preliminary bracing, the second side wall preliminary bracing is connected below the first side wall preliminary bracing, and the inverted arch preliminary bracing is connected below the second side wall preliminary bracing. The first side wall primary support and the second side wall primary support are both located on the side, close to the mountain, of the tunnel, the bias retaining wall is located on the bias side of the tunnel and connected to the lower portion of the arch wall primary support, one end of the inverted arch primary support is connected with the bias retaining wall, and the other end of the inverted arch primary support is connected with the second side wall primary support. The arch wall primary support, the first side wall primary support and the second side wall primary support are connected in a stepped mode, and the supporting counter force on an overlying rock mass on a steep slope can be enhanced; the bias retaining wall serves as a part of a tunnel primary support and can directly resist bias loads, the structural integrity is good, and the structural strength of the primary support is effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of tunnel technology, and in particular to a novel tunnel initial support structure. Background Technology

[0002] With continuous economic development, the requirements for the alignment indicators and vehicle capacity of expressways are becoming increasingly stringent. This inevitably leads to the entrances of large-span expressway tunnels traversing various steep natural slopes (slope > 45°), nature reserves, or ecologically sensitive areas such as water sources. Steep rock and soil masses, meaning that the tunnel's front and one side are both steep rock masses, often present problems such as shallow burial bias and poor slope stability at the tunnel entrance. These tunnels face significant construction difficulties and are prone to various defects during operation.

[0003] Existing tunnel lining technologies typically employ composite lining structures, including initial support and secondary lining. The initial support usually adopts a ring-shaped symmetrical structure. Due to tunnel eccentricity, this symmetrical structure alone is usually insufficient to effectively resist the tunnel eccentricity. It is necessary to add an additional eccentricity retaining wall on the outside of the tunnel lining (the eccentricity side). The eccentricity retaining wall is independently stressed from the initial support, resulting in poor overall integrity. Cracks are easily formed at the contact surface, weakening the overall rigidity.

[0004] Therefore, it is necessary to propose a new type of tunnel initial support structure to solve or at least alleviate the above-mentioned defects. Utility Model Content

[0005] The main purpose of this utility model is to provide a new type of tunnel initial support structure to solve the technical problem that the existing symmetrical initial support structure usually cannot effectively resist tunnel bias pressure, and requires the addition of an additional bias pressure retaining wall on the outside of the tunnel lining (bias pressure side). The bias pressure retaining wall and the initial support are independently stressed, resulting in poor overall integrity.

[0006] To achieve the above objectives, this utility model provides a novel tunnel initial support structure, including initial support for the arch wall, initial support for the first sidewall, initial support for the second sidewall, initial support for the invert arch, and an eccentric retaining wall; wherein,

[0007] The first sidewall initial support is connected below the arch wall initial support, and the second sidewall initial support is connected below the first sidewall initial support. Both the first and second sidewall initial supports are located on the mountain side of the tunnel. The eccentric retaining wall is located on the eccentric side of the tunnel and is connected below the arch wall initial support. One end of the invert arch initial support is connected to the eccentric retaining wall, and the other end is connected to the second sidewall initial support. The arch wall initial support, the first sidewall initial support, the second sidewall initial support, the invert arch initial support, and the eccentric retaining wall together form a closed ring structure.

[0008] Preferably, the cross-section of the arch foot end of the initial support of the arch wall gradually increases from top to bottom, and the top cross-sectional area of ​​the first side wall initial support is smaller than the bottom cross-sectional area of ​​the initial support of the arch wall; and / or the cross-section of the arch foot end of the first side wall initial support gradually increases from top to bottom, and the top cross-sectional area of ​​the second side wall initial support is smaller than the bottom cross-sectional area of ​​the first side wall initial support.

[0009] Preferably, the initial support for the arch wall includes an arch wall steel frame and a first connecting steel plate and a second connecting steel plate respectively connected to both ends of the arch wall steel frame; the initial support for the first side wall includes a first side wall steel frame and a third connecting steel plate and a fourth connecting steel plate respectively connected to both ends of the first side wall steel frame; wherein,

[0010] The first connecting steel plate has a first connecting hole for bolts to pass through, the third connecting steel plate has a second connecting hole that corresponds to the first connecting hole, the third connecting steel plate is connected to the first connecting steel plate by bolts passing through the first connecting hole and the second connecting hole, the second connecting steel plate is connected to the bias retaining wall, and the fourth connecting steel plate is connected to the initial support of the second side wall.

[0011] Preferably, the initial support of the second sidewall includes a second sidewall steel frame and a fifth connecting steel plate and a steel pad respectively connected to both ends of the second sidewall steel frame. The fourth connecting steel plate has a third connecting hole for bolts to pass through, and the fifth connecting steel plate has a fourth connecting hole that corresponds to the third connecting hole. The fifth connecting steel plate is connected to the fourth connecting steel plate by bolts passing through the third connecting hole and the fourth connecting hole. The steel pad is used to support the tunnel arch foot.

[0012] Preferably, the initial support of the invert arch includes an invert arch steel frame, and the invert arch steel frame and the second sidewall steel frame are welded together.

[0013] Preferably, it also includes a first prestressed expansion shell anchor and a first steel pipe pile. The first prestressed expansion shell anchor includes a first end and a second end that are arranged opposite to each other along its own extension direction. The first end is connected to the arch wall steel frame, and the second end is driven into the surrounding rock at an angle upward from the first end.

[0014] The first steel pipe pile is located below the first prestressed expansion shell anchor rod. The first steel pipe pile includes a third end and a fourth end that are arranged opposite to each other along its own extension direction. The third end is connected to the arch wall steel frame, and the fourth end is driven into the surrounding rock inclined downward from the third end.

[0015] Preferably, it further includes a second prestressed expansion shell anchor and a second steel pipe pile. The second prestressed expansion shell anchor includes a fifth end and a sixth end that are arranged opposite to each other along its own extension direction. The fifth end is connected to the first sidewall steel frame, and the sixth end is driven into the surrounding rock at an angle upward from the fifth end.

[0016] The second steel pipe pile is located below the second prestressed expansion shell anchor rod. The second steel pipe pile includes a seventh end and an eighth end that are arranged opposite to each other along its own extension direction. The seventh end is connected to the first side wall steel frame, and the eighth end is driven into the surrounding rock at an angle downward from the seventh end.

[0017] Preferably, the arch steel frame includes an upward-opening arc-shaped segment and a first horizontal segment and a second horizontal segment respectively connected to the two ends of the arc-shaped segment. The first horizontal segment is welded to the second sidewall steel frame, the second horizontal segment is connected to the bias retaining wall, and the arc-shaped segment is connected between the first horizontal segment and the second horizontal segment.

[0018] Preferably, it also includes an arch wall advance pipe shed located outside the arch wall steel frame, and the arch wall advance pipe shed is connected to the arch wall steel frame.

[0019] Preferably, it further includes a sidewall advanced pipe shed located outside the first sidewall steel frame, and the sidewall advanced pipe shed is connected to the first sidewall steel frame.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This utility model provides a novel tunnel initial support structure, including an arch wall initial support, a first sidewall initial support, a second sidewall initial support, an invert arch initial support, and an eccentric retaining wall. The first sidewall initial support is connected below the arch wall initial support, and the second sidewall initial support is connected below the first sidewall initial support. Both the first and second sidewall initial supports are located on the mountain-facing side of the tunnel. The eccentric retaining wall is located on the eccentric side of the tunnel and is connected below the arch wall initial support. One end of the invert arch initial support is connected to the eccentric retaining wall, and the other end is connected to the second sidewall initial support. The arch wall initial support, first sidewall initial support, and second sidewall initial support in this application adopt a stepped connection, which can enhance the supporting reaction force on the overlying rock mass of steep slopes. As part of the tunnel initial support, the eccentric retaining wall can directly resist eccentric loads. This application has good structural integrity and effectively improves the strength of the initial support structure. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure in one embodiment of the present invention;

[0024] Figure 2 This is an application scenario diagram of the overall structure in one embodiment of the present utility model;

[0025] Figure 3 This is a schematic diagram showing the connection details of the initial support of the arch wall and the eccentric retaining wall in one embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram showing the connection details between the initial support of the arch wall and the initial support of the first side wall in one embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram showing the connection details between the initial support of the second sidewall and the initial support of the invert arch in one embodiment of the present invention;

[0028] Figure 6 This is a partial schematic diagram of the bias retaining wall in one embodiment of the present invention.

[0029] The purpose, features, and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0030] Explanation of icon numbers:

[0031] 10. Initial support for the arch wall; 110. Arch wall steel frame; 120. First connecting steel plate; 130. Second connecting steel plate; 20. Initial support for the first side wall; 210. First side wall steel frame; 220. Third connecting steel plate; 30. Initial support for the second side wall; 310. Second side wall steel frame; 320. Steel pad; 40. Initial support for the invert arch; 410. Invert arch steel frame; 411. Curved section; 412. First horizontal section; 50, biased retaining wall; 510, embedded bolt; 520, embedded steel plate; 530, channel steel; 540, rubber pad; 550, reinforced concrete structure; 560, embedded steel arch frame; 610, first prestressed expansion shell anchor; 620, first steel pipe pile; 710, second prestressed expansion shell anchor; 720, second steel pipe pile; 80, arch wall advanced pipe shed; 90, side wall advanced pipe shed. Detailed Implementation

[0032] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0034] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0035] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0036] Please see the appendix Figures 1 to 6 This utility model provides a novel tunnel initial support structure in one embodiment, comprising an arch wall initial support 10, a first sidewall initial support 20, a second sidewall initial support 30, an invert arch initial support 40, and an eccentric retaining wall 50; wherein,

[0037] The first sidewall initial support 20 is connected below the arch wall initial support 10, and the second sidewall initial support 30 is connected below the first sidewall initial support 20. Both the first sidewall initial support 20 and the second sidewall initial support 30 are located on the mountain side of the tunnel. The bias retaining wall 50 is located on the bias side of the tunnel and is connected below the arch wall initial support 10. One end of the invert arch initial support 40 is connected to the bias retaining wall 50, and the other end is connected to the second sidewall initial support 30. The arch wall initial support 10, the first sidewall initial support 20, the second sidewall initial support 30, the invert arch initial support 40, and the bias retaining wall 50 together form a ring-shaped closed structure.

[0038] In this application, the initial support 10 of the arch wall, the initial support 20 of the first side wall, and the initial support 30 of the second side wall are connected in a stepped manner, which can enhance the supporting reaction force on the overlying rock mass of the steep slope; the bias retaining wall 50 is connected to the initial support 10 of the arch wall. As part of the initial support of the tunnel, the bias retaining wall 50 can directly resist the bias load. The overall structure of this application has good integrity, effectively improves the strength of the initial support structure, and meets the requirements of bias geological conditions of steep rock mass.

[0039] In a preferred embodiment, the cross-section of the arch foot end of the initial support 10 of the arch wall gradually increases from top to bottom, and the top cross-sectional area of ​​the first side wall initial support 20 is smaller than the bottom cross-sectional area of ​​the initial support 10 of the arch wall; and / or the cross-section of the arch foot end of the first side wall initial support 20 gradually increases from top to bottom, and the top cross-sectional area of ​​the second side wall initial support 30 is smaller than the bottom cross-sectional area of ​​the first side wall initial support 20.

[0040] Specifically, such as Figure 1 As shown, the gradual increase in cross-sectional area at the arch foot creates a gradient structure, which enhances shear bearing capacity, effectively supports arch loads, and resists eccentric pressure caused by lateral terrain. In this embodiment, a large arch foot with initial support is attached to the eccentric retaining wall 50, which increases the support stiffness and lateral resistance, effectively solving the problem of shallow-buried eccentric pressure.

[0041] In a preferred embodiment, the initial support 10 for the arch wall includes an arch wall steel frame 110 and a first connecting steel plate 120 and a second connecting steel plate 130 respectively connected to both ends of the arch wall steel frame 110. The initial support 20 for the first side wall includes a first side wall steel frame 210 and a third connecting steel plate 220 and a fourth connecting steel plate (not shown) respectively connected to both ends of the first side wall steel frame 210.

[0042] The first connecting steel plate 120 has a first connecting hole for bolts to pass through, and the third connecting steel plate 220 has a second connecting hole that corresponds to the first connecting hole. The third connecting steel plate 220 is connected to the first connecting steel plate 120 by bolts passing through the first connecting hole and the second connecting hole. The second connecting steel plate 130 is connected to the bias retaining wall 50, and the fourth connecting steel plate is connected to the second side wall initial support 30.

[0043] Specifically, by opening a first connecting hole on the first connecting steel plate 120 and opening a corresponding second connecting hole on the third connecting steel plate 220, the third connecting steel plate 220 can be reliably connected to the first connecting steel plate 120 by bolts passing through these two connecting holes. This has high connection strength and stability, effectively ensuring a firm connection between the initial support 10 of the arch wall and the initial support 20 of the first side wall, enhancing the collaborative working ability of the overall support structure, and jointly bearing external loads such as surrounding rock pressure.

[0044] The second connecting steel plate 130 is connected to the bias retaining wall 50, and the fourth connecting steel plate is connected to the initial support 30 of the second side wall, so that the entire support structure can be effectively connected with different structural components around it to form an organic whole.

[0045] In a preferred embodiment, the initial support 30 for the second sidewall includes a second sidewall steel frame 310 and a fifth connecting steel plate (not shown) and a steel pad 320 respectively connected to both ends of the second sidewall steel frame 310. The fourth connecting steel plate has a third connecting hole for bolts to pass through, and the fifth connecting steel plate has a fourth connecting hole that corresponds to the third connecting hole. The fifth connecting steel plate is connected to the fourth connecting steel plate by bolts passing through the third connecting hole and the fourth connecting hole. The steel pad 320 is used to pad at the tunnel arch foot.

[0046] Specifically, the fourth connecting steel plate has a third connecting hole, and the fifth connecting steel plate has a corresponding fourth connecting hole. Bolts are used to connect the two connecting holes. This bolted connection method offers high strength and stability, ensuring a secure connection between the initial support 30 of the second sidewall and the initial support 20 of the first sidewall. This allows the various support structures to form a unified whole, jointly bearing the surrounding rock pressure and effectively preventing instability or damage to the support structure due to weak connections.

[0047] As a preferred embodiment, it also includes a first prestressed expansion shell anchor 610 and a first steel pipe pile 620. The first prestressed expansion shell anchor 610 includes a first end (not shown in the figure) and a second end (not shown in the figure) that are arranged opposite to each other along its own extension direction. The first end is connected to the arch wall steel frame 110, and the second end is driven into the surrounding rock inclined upward from the first end.

[0048] The first steel pipe pile 620 is located below the first prestressed expansion shell anchor rod 610. The first steel pipe pile 620 includes a third end (not shown in the figure) and a fourth end (not shown in the figure) arranged opposite to each other along its own extension direction. The third end is connected to the arch wall steel frame 110, and the fourth end is driven into the surrounding rock inclined downward from the third end.

[0049] As another preferred embodiment, it also includes a second prestressed expansion shell anchor 710 and a second steel pipe pile 720. The second prestressed expansion shell anchor 710 includes a fifth end (not shown in the figure) and a sixth end (not shown in the figure) arranged opposite to each other along its own extension direction. The fifth end is connected to the first side wall steel frame 210, and the sixth end is driven into the surrounding rock inclined upward from the fifth end.

[0050] The second steel pipe pile 720 is located below the second prestressed expansion shell anchor 710. The second steel pipe pile 720 includes a seventh end (not shown in the figure) and an eighth end (not shown in the figure) arranged opposite to each other along its own extension direction. The seventh end is connected to the first side wall steel frame 210, and the eighth end is driven into the surrounding rock inclined downward from the seventh end.

[0051] Specifically, prestressed expansion shell anchors, through their unique tensioning device and prestressed design, provide strong pull-out resistance and stability, ensuring that the arch foot is not easily displaced or deformed under external forces. Steel pipe piles, with their rigidity and strength, provide additional support to the arch foot, further enhancing its stability. The combined use of prestressed expansion shell anchors and steel pipe piles can significantly improve the overall bearing capacity of the support structure. As a specific example, Φ50mm prestressed expansion shell anchors are used, and Φ72mm steel pipe piles are used.

[0052] Furthermore, the initial support 40 for the invert arch includes an invert arch steel frame 410, which is welded to the second sidewall steel frame 310.

[0053] In a preferred embodiment, the arch steel frame 410 includes an upward-opening arc-shaped segment 411 and a first horizontal segment 412 and a second horizontal segment (not shown) respectively connected to the two ends of the arc-shaped segment 411. The first horizontal segment 412 is welded to the second side wall steel frame 310, the second horizontal segment is connected to the bias retaining wall 50, and the arc-shaped segment 411 is connected between the first horizontal segment 412 and the second horizontal segment.

[0054] The first horizontal section 412 and the second horizontal section are connected to the second side wall steel frame 310 and the eccentric retaining wall 50, respectively, so that the force borne by the invert arch steel frame 410 is transferred to the surrounding structure, enabling the entire support system to work together to resist the surrounding rock pressure and improve the overall stability of the tunnel structure.

[0055] Furthermore, it also includes an arch wall advance pipe shed 80 located outside the arch wall steel frame 110, and the arch wall advance pipe shed 80 is connected to the arch wall steel frame 110.

[0056] Furthermore, it also includes a side wall advanced pipe shed 90 located outside the first side wall steel frame 210, and the side wall advanced pipe shed 90 is connected to the first side wall steel frame 210.

[0057] By constructing the arch wall pre-support pipe roof 80 and the sidewall pre-support pipe roof 90 at the tunnel face, a pre-support structure is formed in the longitudinal direction of the tunnel, which can improve the top support capacity and effectively control the loosening and deformation of the surrounding rock during the excavation of the main tunnel.

[0058] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A novel tunnel primary support structure characterized by, This includes initial support for the arch wall, initial support for the first side wall, initial support for the second side wall, initial support for the invert arch, and eccentric retaining wall; among which, The first sidewall initial support is connected below the arch wall initial support, and the second sidewall initial support is connected below the first sidewall initial support. Both the first and second sidewall initial supports are located on the mountain side of the tunnel. The eccentric retaining wall is located on the eccentric side of the tunnel and is connected below the arch wall initial support. One end of the invert arch initial support is connected to the eccentric retaining wall, and the other end is connected to the second sidewall initial support. The arch wall initial support, the first sidewall initial support, the second sidewall initial support, the invert arch initial support, and the eccentric retaining wall together form a closed ring structure.

2. The new type of tunnel primary support structure according to claim 1, characterized in that, The cross-section of the arch foot end of the initial support of the arch wall gradually increases from top to bottom, and the top cross-sectional area of ​​the first side wall initial support is smaller than the bottom cross-sectional area of ​​the initial support of the arch wall; and / or the cross-section of the arch foot end of the first side wall initial support gradually increases from top to bottom, and the top cross-sectional area of ​​the second side wall initial support is smaller than the bottom cross-sectional area of ​​the first side wall initial support.

3. The novel initial support structure for tunnel as claimed in claim 1 wherein, The initial support for the arch wall includes an arch wall steel frame and a first connecting steel plate and a second connecting steel plate respectively connected to both ends of the arch wall steel frame; the initial support for the first side wall includes a first side wall steel frame and a third connecting steel plate and a fourth connecting steel plate respectively connected to both ends of the first side wall steel frame; wherein, The first connecting steel plate has a first connecting hole for bolts to pass through, the third connecting steel plate has a second connecting hole that corresponds to the first connecting hole, the third connecting steel plate is connected to the first connecting steel plate by bolts passing through the first connecting hole and the second connecting hole, the second connecting steel plate is connected to the bias retaining wall, and the fourth connecting steel plate is connected to the initial support of the second side wall.

4. The new type of tunnel primary support structure according to claim 3, characterized in that, The initial support for the second sidewall includes a second sidewall steel frame and a fifth connecting steel plate and a steel pad respectively connected to both ends of the second sidewall steel frame. The fourth connecting steel plate has a third connecting hole for bolts to pass through. The fifth connecting steel plate has a fourth connecting hole that corresponds to the third connecting hole. The fifth connecting steel plate is connected to the fourth connecting steel plate by bolts passing through the third connecting hole and the fourth connecting hole. The steel pad is used to support the tunnel arch foot.

5. The new type of tunnel primary support structure according to claim 4, characterized in that, The initial support for the invert arch includes an invert arch steel frame, which is welded to the second sidewall steel frame.

6. The novel initial support structure of the tunnel according to claim 3, characterized in that, It also includes a first prestressed expansion shell anchor rod and a first steel pipe pile. The first prestressed expansion shell anchor rod includes a first end and a second end that are arranged opposite to each other along its own extension direction. The first end is connected to the arch wall steel frame, and the second end is driven into the surrounding rock inclined upward from the first end. The first steel pipe pile is located below the first prestressed expansion shell anchor rod. The first steel pipe pile includes a third end and a fourth end that are arranged opposite to each other along its own extension direction. The third end is connected to the arch wall steel frame, and the fourth end is driven into the surrounding rock inclined downward from the third end.

7. The novel initial support structure of the tunnel according to claim 4, characterized in that, It also includes a second prestressed expansion shell anchor and a second steel pipe pile. The second prestressed expansion shell anchor includes a fifth end and a sixth end that are arranged opposite to each other along its own extension direction. The fifth end is connected to the first side wall steel frame, and the sixth end is driven into the surrounding rock at an angle upward from the fifth end. The second steel pipe pile is located below the second prestressed expansion shell anchor rod. The second steel pipe pile includes a seventh end and an eighth end that are arranged opposite to each other along its own extension direction. The seventh end is connected to the first side wall steel frame, and the eighth end is driven into the surrounding rock at an angle downward from the seventh end.

8. The novel tunnel initial support structure according to claim 5, characterized in that, The arch steel frame includes an upward-opening arc-shaped section and a first horizontal section and a second horizontal section respectively connected to the two ends of the arc-shaped section. The first horizontal section is welded to the second side wall steel frame, the second horizontal section is connected to the bias retaining wall, and the arc-shaped section is connected between the first horizontal section and the second horizontal section.

9. The novel tunnel initial support structure according to claim 3, characterized in that, It also includes an arch wall advance pipe shed located outside the arch wall steel frame, and the arch wall advance pipe shed is connected to the arch wall steel frame.

10. The new type of tunnel primary support structure according to claim 9, characterized in that, It also includes a sidewall advanced pipe shed located outside the first sidewall steel frame, and the sidewall advanced pipe shed is connected to the first sidewall steel frame.

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