Temporary supporting structure of shallow-buried gully bilateral bias pressure tunnel portal section

Abstract

The utility model provides a temporary support structure of a shallow-buried gully bilateral bias pressure tunnel portal section, which comprises a left hole temporary protection arch, a right hole temporary protection arch and a cross brace assembly, the left hole temporary protection arch is arc-shaped, a first lap joint end is used for being in lap joint at an arch foot position of a tunnel left hole close to a tunnel right hole, and a second lap joint end is used for being in lap joint with a second lap joint end. The second lap joint end is in lap joint with the excavation contour face of the left tunnel hole, the right tunnel temporary protection arch is in an arc shape, the third lap joint end is used for being in lap joint with an arch foot, close to the left tunnel hole, of the right tunnel hole, and the fourth lap joint end is in lap joint with the excavation contour face of the right tunnel hole. The overall supporting structure formed by the left hole temporary protection arch, the right hole temporary protection arch and the transverse supporting assembly improves the bias pressure resistance and the structural stability, by means of the temporary supporting structure, the tunnel portal section does not need to be shrunk to the position where earth covering on the bias pressure side meets the hole entering requirement, and the bias pressure problem of the tunnel portal section is effectively solved.

Description

Technical Field

[0001] The utility model relates to the technical field of tunnels, in particular to a temporary support structure for the portal section of a shallow-buried gully double-sided biased-pressure tunnel. Background Technique

[0002] With the development of China's economic construction, highways have begun to extend to remote mountainous areas. Affected by factors such as topography and environmental protection, it is becoming increasingly difficult to select highway routes, resulting in the portal of the tunnel being located in an unfavorable terrain. Among them, when the portal section of the tunnel is located in a shallow-buried gully terrain, since the gully is located between the left tunnel and the right tunnel, at this time, the inner sides of the left tunnel and the right tunnel are biased, and the bias will have an adverse impact on the tunnel. For example, the bias will cause the load on the tunnel lining structure to be asymmetric, and it is extremely easy to cause shear failure of the lining structure.

[0003] At present, for the portal section of the tunnel in such a terrain, the conventional method is to reduce the portal section of the tunnel to the position where the overburden on the biased side meets the requirement for entering the tunnel, make the portal into an end wall type, and then backfill the soil and stone between the left tunnel and the right tunnel. However, although this method can effectively reduce the bias problem of the portal section of the tunnel, it results in too high a slope of the subgrade section, increasing the accident risk of the subgrade section. For example, it increases the risks of landslides, collapses, falling rocks, etc.

[0004] In view of this, it is necessary to propose a temporary support structure for the portal section of a shallow-buried gully double-sided biased-pressure tunnel to solve or at least alleviate the above defects. Content of the Utility Model

[0005] The main purpose of the utility model is to provide a temporary support structure for the portal section of a shallow-buried gully double-sided biased-pressure tunnel, so as to solve the technical problem that when the portal section of the tunnel is located in a shallow-buried gully terrain in the prior art, it is necessary to reduce the portal section of the tunnel to the position where the overburden on the biased side meets the requirement for entering the tunnel, resulting in too high a slope of the subgrade section and increasing the accident risk of the subgrade section.

[0006] To achieve the above purpose, the utility model provides a temporary support structure for the portal section of a shallow-buried gully double-sided biased-pressure tunnel, which includes a left tunnel temporary arch provided on the biased side of the left tunnel of the tunnel, a right tunnel temporary arch provided on the biased side of the right tunnel of the tunnel, and a cross brace assembly connected between the left tunnel temporary arch and the right tunnel temporary arch; wherein,

[0007] The left tunnel temporary arch is arc-shaped, and the left tunnel temporary arch includes a first lapping end and a second lapping end arranged oppositely along its own extending direction. The first lapping end is used for lapping at the arch foot of the left tunnel close to the right tunnel, and the second lapping end lapping on the excavation contour surface of the left tunnel.

[0008] The temporary arch support on the right side is arc-shaped. The temporary arch support on the right side includes a third lapping end and a fourth lapping end that are oppositely arranged along its extending direction. The third lapping end is used for lapping at the arch foot of the right tunnel near the left tunnel, and the fourth lapping end laps on the excavation contour surface of the right tunnel.

[0009] Preferably, the temporary arch support on the left side includes a plurality of left-tunnel temporary arch support segments that are sequentially spliced along the contour line of the left tunnel. Each left-tunnel temporary arch support segment includes a left-tunnel arch support main body and two first connection components respectively connected to both ends of the left-tunnel arch support main body. Adjacent two left-tunnel temporary arch support segments are connected through the first connection components.

[0010] Preferably, the first connection component includes a first connection plate and a second connection plate that are perpendicular to each other. The first connection plate is connected to the end of the left-tunnel arch support main body. The second connection plate is connected to the first connection plate and is located outside the left-tunnel arch support main body. Among them, the first connection plate is provided with a first connection hole for a bolt to penetrate through. The first connection plate of the previous left-tunnel temporary arch support segment is connected to the next left-tunnel temporary arch support segment by the bolt penetrating through the first connection hole. One end of the cross-brace component is connected to the second connection plate.

[0011] Preferably, the temporary arch support on the right side includes a plurality of right-tunnel temporary arch support segments that are sequentially spliced along the contour line of the right tunnel. Each right-tunnel temporary arch support segment includes a right-tunnel arch support main body and two second connection components respectively connected to both ends of the right-tunnel arch support main body. Adjacent two right-tunnel temporary arch support segments are connected through the second connection components.

[0012] Preferably, the second connection component includes a third connection plate and a fourth connection plate that are perpendicular to each other. The third connection plate is connected to the end of the right-tunnel arch support main body. The fourth connection plate is connected to the third connection plate and is located outside the right-tunnel arch support main body. Among them, the third connection plate is provided with a second connection hole for a bolt to penetrate through. The third connection plate of the previous right-tunnel temporary arch support segment is connected to the next right-tunnel temporary arch support segment by the bolt penetrating through the second connection hole. The other end of the cross-brace component is connected to the fourth connection plate.

[0013] Preferably, the cross-brace component includes a plurality of cross-brace layers arranged at intervals in the vertical direction. Each cross-brace layer includes a plurality of cross-braces arranged at intervals in the longitudinal direction of the tunnel.

[0014] Preferably, each of the cross braces includes a first end backing plate, a cross brace main body section, and a second end backing plate that are sequentially connected along the extension direction of the cross brace itself. The second connecting plate is provided with a third connecting hole for a bolt to pass through. The first end backing plate is provided with a fourth connecting hole arranged in one-to-one correspondence with the third connecting hole. The fourth connecting plate is provided with a fifth connecting hole for a bolt to pass through. The second end backing plate is provided with a sixth connecting hole arranged in one-to-one correspondence with the fifth connecting hole. Among them, the second connecting plate is connected to the first end backing plate by a bolt passing through the third connecting hole and the fourth connecting hole. The fourth connecting plate is connected to the second end backing plate by a bolt passing through the fifth connecting hole and the sixth connecting hole.

[0015] Preferably, both the left tunnel arch protection main body and the right tunnel arch protection main body are corrugated steel plates.

[0016] Preferably, a first water collecting hopper is connected to the outside of the corrugated steel plate near the arch foot of the left tunnel of the tunnel, and a second water collecting hopper is connected to the outside of the corrugated steel plate near the arch foot of the right tunnel of the tunnel.

[0017] Preferably, the cross brace main body section is an I20 I-beam.

[0018] Compared with the prior art, the present utility model has the following beneficial effects:

[0019] The present utility model provides a temporary support structure for the entrance section of a shallow-buried gully double-sided bias pressure tunnel, including a left tunnel temporary arch protection, a right tunnel temporary arch protection, and a cross brace assembly. The left tunnel temporary arch protection is arc-shaped and includes a first overlapping end and a second overlapping end that are oppositely arranged along the extension direction of the left tunnel temporary arch protection itself. The first overlapping end is used for overlapping at the arch foot of the left tunnel of the tunnel near the right tunnel, and the second overlapping end overlaps on the excavation contour surface of the left tunnel of the tunnel. The right tunnel temporary arch protection is arc-shaped and includes a third overlapping end and a fourth overlapping end that are oppositely arranged along the extension direction of the right tunnel temporary arch protection itself. The third overlapping end is used for overlapping at the arch foot of the right tunnel of the tunnel near the left tunnel, and the fourth overlapping end overlaps on the excavation contour surface of the right tunnel of the tunnel. The overall support structure formed by the left tunnel temporary arch protection, the right tunnel temporary arch protection, and the cross brace assembly of the present application improves the anti-bias pressure ability and structural stability. By using the temporary support structure of the present application, it is not necessary to reduce the entrance section of the tunnel to the position where the overburden on the bias pressure side meets the requirements for entering the tunnel, effectively reducing the bias pressure problem of the entrance section of the tunnel. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0021] Figure 1 Schematic diagram of the overall structure in an embodiment of the present invention;

[0022] Figure 2 Application scenario diagram of the schematic diagram of the overall structure in an embodiment of the present invention;

[0023] Figure 3 For Figure 2 Partial enlarged schematic diagram in;

[0024] Figure 4 Schematic diagram of the structure of the temporary support arch segment of the left tunnel in an embodiment of the present invention.

[0025] The realization of the purpose, functional features and advantages of the present invention will be further described with reference to the embodiments and the drawings.

[0026] Explanation of the reference numerals in the drawings:

[0027] 1. Left tunnel of the tunnel; 10. Temporary support arch of the left tunnel; 110. First overlapping end; 120. Second overlapping end; 130. Excavation contour surface of the left tunnel of the tunnel; 140. Temporary support arch segment of the left tunnel; 141. Main body of the left tunnel support arch; 142. First connection component; 1421. First connecting plate; 1422. Second connecting plate; 2. Right tunnel of the tunnel; 20. Temporary support arch of the right tunnel; 210. Third overlapping end; 220. Fourth overlapping end; 230. Excavation contour surface of the right tunnel of the tunnel; 30. Cross brace component; 310. Cross brace; 311. First end backing plate; 312. Main body section of the cross brace. Detailed implementation manners

[0028] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present utility model are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as described in the attached drawings). If this specific posture changes, the directional indications will change accordingly.

[0031] In addition, the descriptions involving "first", "second", etc. in the present utility model are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

[0032] Please refer to the attached Figures 1 to 4 , a temporary support structure for the portal section of a shallow-buried gully double-sidedly biased tunnel in an embodiment provided by the present utility model, includes a left-hole temporary arch 10 provided on the biased side of the left hole 1 of the tunnel, a right-hole temporary arch 20 provided on the biased side of the right hole 2 of the tunnel, and a cross-brace assembly 30 connected between the left-hole temporary arch 10 and the right-hole temporary arch 20; wherein,

[0033] The left-hole temporary arch 10 is arc-shaped. The left-hole temporary arch 10 includes a first overlapping end 110 and a second overlapping end 120 that are oppositely arranged along its own extending direction. The first overlapping end 110 is used to overlap at the arch foot of the left hole 1 of the tunnel near the right hole 2 of the tunnel, and the second overlapping end 120 overlaps on the excavation contour surface 130 of the left hole of the tunnel;

[0034] The right-hole temporary arch 20 is arc-shaped. The right-hole temporary arch 20 includes a third overlapping end 210 and a fourth overlapping end 220 that are oppositely arranged along its own extending direction. The third overlapping end 210 is used to overlap at the arch foot of the right hole 2 of the tunnel near the left hole 1 of the tunnel, and the fourth overlapping end 220 overlaps on the excavation contour surface 230 of the right hole of the tunnel.

[0035] In order to alleviate the double-sided bias problem in the solution of the present application, the inner soil body of the excavated part in the left hole 1 and the right hole 2 of the tunnel can be excavated first, for example Figure 1After the shown excavation contour line is completed, the temporary left tunnel arch 10 and the temporary right tunnel arch 20 can be installed. Among them, the temporary left tunnel arch 10 and the temporary right tunnel arch 20 can be made of steel arches or other arches with increased structural strength. Preferably, both the temporary left tunnel arch 10 and the temporary right tunnel arch 20 are corrugated steel plate arches. The corrugated steel plate has better load-bearing capacity, convenient construction characteristics, and waterproof effect. Further, in order to facilitate the installation of the corrugated steel plate, the corrugated steel plate lap joint can be leveled and a 15 cm C20 concrete cushion can be laid. After the temporary left tunnel arch 10 and the temporary right tunnel arch 20 are installed, the remaining soil in the left tunnel 1 and the right tunnel 2 of the tunnel can be excavated, and then the initial support inside the tunnel can be constructed in time. At this time, the corresponding temporary left tunnel arch 10, temporary right tunnel arch 20 and cross brace assembly 30 can be removed. The overall support structure formed by the temporary left tunnel arch 10, temporary right tunnel arch 20 and cross brace assembly 30 of the present application improves the anti-bias pressure ability and structural stability.

[0036] It should be noted that the present application cleverly connects the temporary left tunnel arch 10 and the temporary right tunnel arch 20 into a whole through the cross brace assembly 30. The cross brace assembly 30 can conduct the mountain pressure, make full use of the mutual balance and cancellation of the inner side bias pressure of the left tunnel 1 of the tunnel and the inner side bias pressure of the right tunnel 2 of the tunnel, so as to cleverly relieve the bias pressure problem by the characteristics of the double-sided bias pressure in the gully, and can improve the stability of the overall structure.

[0037] As a preferred embodiment, the temporary left tunnel arch 10 includes a plurality of temporary left tunnel arch segments 140 sequentially spliced along the contour line of the left tunnel 1 of the tunnel. Each temporary left tunnel arch segment 140 includes a left tunnel arch main body 141 and two first connection components 142 respectively connected to both ends of the left tunnel arch main body 141. Adjacent two temporary left tunnel arch segments 140 are connected by the first connection components 142.

[0038] As a preferred embodiment, the first connection component 142 includes a first connection plate 1421 and a second connection plate 1422 that are perpendicular to each other. The first connection plate 1421 is connected to the end of the left tunnel arch main body 141. The second connection plate 1422 is connected to the first connection plate 1421 and is located outside the left tunnel arch main body 141. Among them, the first connection plate 1421 is provided with a first connection hole (not shown in the figure) for the bolt to penetrate. The first connection plate 1421 of the previous temporary left tunnel arch segment 140 is connected to the next temporary left tunnel arch segment 140 by the bolt penetrating the first connection hole. One end of the cross brace assembly 30 is connected to the second connection plate 1422.

[0039] As a preferred embodiment, the temporary arch support 20 on the right side of the tunnel includes a plurality of temporarily-formed arch support segments on the right side of the tunnel (not shown in the figure) that are sequentially spliced along the contour line of the right tunnel 2 of the tunnel. Each of the temporarily-formed arch support segments on the right side of the tunnel includes a main body of the arch support on the right side of the tunnel (not shown in the figure) and two second connection components (not shown in the figure) respectively connected to both ends of the main body of the arch support on the right side of the tunnel. Adjacent two temporarily-formed arch support segments on the right side of the tunnel are connected through the second connection components.

[0040] As a preferred embodiment, the second connection component includes a third connection plate (not shown in the figure) and a fourth connection plate (not shown in the figure) that are perpendicular to each other. The third connection plate is connected to the end of the main body of the arch support on the right side of the tunnel. The fourth connection plate is connected to the third connection plate and is located outside the main body of the arch support on the right side of the tunnel. Among them, the third connection plate is provided with a second connection hole for a bolt to penetrate. The third connection plate of the previous temporarily-formed arch support segment on the right side of the tunnel is connected to the next temporarily-formed arch support segment on the right side of the tunnel through the bolt penetrating the second connection hole. The other end of the cross bracing component 30 is connected to the fourth connection plate.

[0041] Furthermore, the cross bracing component 30 includes a plurality of cross bracing layers arranged at intervals in the vertical direction. Each of the cross bracing layers includes a plurality of cross braces 310 arranged at intervals in the depth direction of the tunnel. As an optional example, the cross bracing component 30 includes two cross bracing layers arranged at intervals in the vertical direction. Preferably, the cross braces 310 are made of I-beam cross braces 310@50cm and are divided into upper and lower layers. Further, diagonal braces can be added between the cross braces 310 according to the span to improve the structural stability.

[0042] As a preferred embodiment, each of the cross braces 310 includes a first end backing plate 311, a cross brace main body section 312, and a second end backing plate (not shown in the figure) that are sequentially connected along its own extending direction. The second connection plate 1422 is provided with a third connection hole (not shown in the figure) for a bolt to penetrate. The first end backing plate 311 is provided with a fourth connection hole (not shown in the figure) arranged in one-to-one correspondence with the third connection hole. The fourth connection plate is provided with a fifth connection hole (not shown in the figure) for a bolt to penetrate. The second end backing plate is provided with a sixth connection hole (not shown in the figure) arranged in one-to-one correspondence with the fifth connection hole. Among them, the second connection plate 1422 is connected to the first end backing plate 311 through the bolt penetrating the third connection hole and the fourth connection hole. The fourth connection plate is connected to the second end backing plate through the bolt penetrating the fifth connection hole and the sixth connection hole.

[0043] Specifically, by the method of passing bolts through the connection holes, the first end backing plate 311, the cross brace main body section 312, the second end backing plate, and the two connection plates are tightly connected together, greatly enhancing the connection strength and stability of the entire cross brace 310 structure. The method of bolt connection can facilitate disassembly and installation.

[0044] Furthermore, both the left tunnel arch protection main body 141 and the right tunnel arch protection main body are corrugated steel plates. Corrugated steel plates have better load-bearing capacity and the characteristics of convenient construction. After being connected with the cross bracing 310 as a whole, they can effectively relieve the lateral pressure inside the tunnel.

[0045] As a preferred embodiment, a first water collecting hopper (not shown in the figure) is connected to the outer side of the corrugated steel plate near the arch foot of the left tunnel 1, and a second water collecting hopper (not marked in the figure) is connected to the outer side of the corrugated steel plate near the arch foot of the right tunnel 2. Specifically, on the outer side of the corrugated steel plate, preferably, the first water collecting hopper and the second water collecting hopper are arranged near the tunnel arch foot to collect the accumulated water from the outer side of the corrugated steel plate. On this basis, the first water collecting hopper and the second water collecting hopper can timely drain the accumulated water on the outer side of the corrugated steel plate to the tunnel drainage system through a drain pipe, so as to relieve the water pressure outside the tunnel.

[0046] As a preferred example, the cross bracing main body section 312 is an I20 steel beam, and the I20 steel beam has good mechanical properties, bending resistance, and the advantages of being easy to process and install.

[0047] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A temporary support structure for a shallow gully double-sided biased tunnel portal section, characterized in that: It includes a temporary left tunnel protection arch arranged on the biased side of the left tunnel, a temporary right tunnel protection arch arranged on the biased side of the right tunnel, and a cross brace assembly connected between the temporary left tunnel protection arch and the temporary right tunnel protection arch; wherein, The temporary protection arch of the left tunnel is in an arc shape, and comprises a first overlapping end and a second overlapping end which are arranged opposite to each other along its own extension direction, wherein the first overlapping end is used to overlap the arch foot of the left tunnel near the right tunnel, and the second overlapping end is overlapped on the excavation contour surface of the left tunnel; The temporary arch protection for the right tunnel is in an arc shape and includes a third overlapping end and a fourth overlapping end which are arranged relatively to each other along its own extension direction. The third overlapping end is used to overlap the arch foot of the right tunnel of the tunnel near the left tunnel, and the fourth overlapping end is overlapped on the excavation contour surface of the right tunnel of the tunnel.

2. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 1 is characterized in that: The left tunnel temporary arch protection segment includes a plurality of left tunnel temporary arch protection segments spliced ​​in sequence along the left tunnel contour line of the tunnel, each of the left tunnel temporary arch protection segments includes a left tunnel arch protection body and two first connecting components respectively connected to the two ends of the left tunnel arch protection body, and two adjacent left tunnel temporary arch protection segments are connected by the first connecting components.

3. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 2 is characterized in that: The first connecting assembly includes a first connecting plate and a second connecting plate which are perpendicular to each other, wherein the first connecting plate is connected to the end of the left hole arch protection body, and the second connecting plate is connected to the first connecting plate and is located on the outside of the left hole arch protection body, wherein the first connecting plate is provided with a first connecting hole for bolts to pass through, and the first connecting plate of the previous left hole temporary arch protection segment is connected to the next left hole temporary arch protection segment by bolts passing through the first connecting hole, and one end of the cross brace assembly is connected to the second connecting plate.

4. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 3 is characterized in that: The right-hole temporary arch protection segment includes a plurality of right-hole temporary arch protection segments spliced ​​in sequence along the right-hole contour line of the tunnel, each of the right-hole temporary arch protection segments includes a right-hole arch protection body and two second connecting components respectively connected to the two ends of the right-hole arch protection body, and two adjacent right-hole temporary arch protection segments are connected by the second connecting components.

5. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 4 is characterized in that: The second connecting assembly includes a third connecting plate and a fourth connecting plate which are perpendicular to each other, wherein the third connecting plate is connected to the end of the right hole arch protection body, and the fourth connecting plate is connected to the third connecting plate and is located on the outside of the right hole arch protection body, wherein the third connecting plate is provided with a second connecting hole for bolts to pass through, and the third connecting plate of the previous right hole temporary arch protection segment is connected to the next right hole temporary arch protection segment by bolts passing through the second connecting hole, and the other end of the cross brace assembly is connected to the fourth connecting plate.

6. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 5 is characterized in that: The cross brace assembly includes a plurality of cross brace layers arranged at intervals in the vertical direction, and each of the cross brace layers includes a plurality of cross braces arranged at intervals in the longitudinal direction of the tunnel.

7. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 6 is characterized in that: Each of the cross braces includes a first end pad, a cross brace main section and a second end pad that are sequentially connected along its own extension direction, the second connecting plate is provided with a third connecting hole for bolts to pass through, the first end pad is provided with a fourth connecting hole that is arranged one-to-one with the third connecting hole, the fourth connecting plate is provided with a fifth connecting hole that is arranged one-to-one with the fifth connecting hole, wherein the second connecting plate is connected to the first end pad by bolts passing through the third connecting hole and the fourth connecting hole, and the fourth connecting plate is connected to the second end pad by bolts passing through the fifth connecting hole and the sixth connecting hole.

8. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 4 is characterized in that: The left tunnel arch protection body and the right tunnel arch protection body are both corrugated steel plates.

9. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 8, characterized in that: The outer side of the corrugated steel plate located near the arch foot of the left tunnel is connected to a first water collecting bucket, and the outer side of the corrugated steel plate located near the arch foot of the right tunnel is connected to a second water collecting bucket.

10. The temporary support structure for the double-side biased tunnel portal section of a shallow gully according to claim 7, characterized in that: The main section of the cross brace is I20 I-beam.

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