Support structure and construction method for auxiliary channel entering large-section tunnel intersection

Abstract

The present disclosure relates to the technical field of supporting structure, in particular to a supporting structure for assisting channel to enter large-section tunnel intersection section and a construction method. The supporting structure comprises a horizontal channel, the extension direction of the horizontal channel is perpendicular to the preset trend of the tunnel, a first supporting structure, a second supporting structure and a door body structure are arranged in the horizontal channel to support the rock stratum. The first supporting structure is arranged in the horizontal channel, the second supporting structure is arranged at the gap position of the first supporting structure, and the door body structure is arranged at the position perpendicular to the trend of the horizontal channel. The first supporting structure, the second supporting structure and the door body structure are arranged, the second supporting structure is connected with the first supporting structure, the door body structure is connected with the first supporting structure, a stable supporting structure for supporting the horizontal channel is formed, the structural stability of the horizontal channel is improved, the problem of stress concentration is avoided, the construction difficulty is effectively reduced, and the construction safety is improved.

Description

Technical Field

[0001] This disclosure relates to the field of support structure technology, and in particular to a support structure and construction method for an auxiliary passage entering a large-section tunnel intersection. Background Technology

[0002] During tunnel excavation, the main tunnel is usually excavated by first constructing an auxiliary passage (inclined shaft or transverse passage) downwards, and then excavation begins at the intersection of the auxiliary passage and the main tunnel. When there are multiple main tunnels, the tunnel cross-section at the intersection of the auxiliary passage and the main tunnel is relatively large. When using the auxiliary passage as the entry point to enter the main tunnel at the intersection transition section (gateway), problems arise such as a large excavation cross-section, complex stress distribution at the intersection transition section (gateway), high stress concentration, limited working space, high construction difficulty, and high safety risks. Summary of the Invention

[0003] To address the aforementioned technical issues, this disclosure provides a support structure and construction method for an auxiliary passage entering a large-section tunnel intersection.

[0004] The support structure for the auxiliary passage entering the intersection of a large-section tunnel provided in this disclosure includes:

[0005] A transverse passage, the extension direction of which is perpendicular to the predetermined direction of the tunnel, the transverse passage including a first passage and a second passage, the first passage and the second passage being arranged in a vertical direction, and the second passage being located above the first passage;

[0006] The first support structure is located near the inner wall of the transverse passage, and a gap is formed in the first support structure at a position corresponding to the preset tunnel entrance.

[0007] The second support structure is a grid structure, and the second support structure is located at the notch and connected to the first support structure.

[0008] The door structure is located within the transverse passage and is perpendicular to the extension direction of the transverse passage. It includes a first door frame bracket for communicating with the first passage and a second door frame bracket for communicating with the second passage. Both the first door frame bracket and the second door frame bracket are connected to the first support structure via first support rods. The door structure also includes a plurality of second support rods located above the first door frame brackets. Each second support rod is parallel to the first support rod, and both ends of the second support rod are connected to the first support structure.

[0009] Optionally, a partition layer is provided between the first door frame support and the second door frame support. The partition layer includes a reserved layer and a steel frame concrete layer positioned above the reserved layer. The steel frame concrete layer includes a steel frame, which is connected to the first support structure.

[0010] Optionally, the large-section tunnel includes a main tunnel and a first sub-tunnel and a second sub-tunnel, both of which are connected to the main tunnel. The first sub-tunnel and the second sub-tunnel are arranged adjacent to each other. The cross passage is located between the main tunnel and the first and second sub-tunnels. The first support structure includes at least two gaps, which are respectively arranged to correspond to the first sub-tunnel and the second sub-tunnel. The second support structure is provided at each gap.

[0011] Optionally, during the excavation of the first sub-tunnel and the second sub-tunnel, a first reinforcing ring beam is provided at a predetermined position in the first sub-tunnel and the second sub-tunnel. The first reinforcing ring beam is located outside the first sub-tunnel and the second sub-tunnel and is connected to the second support structure.

[0012] Optionally, a first advanced small guide grouting zone is provided on the outer side of the arch of the first reinforcing ring beam.

[0013] Optionally, the first support structure further includes a notch corresponding to the main tunnel, at which the second support structure is disposed.

[0014] Optionally, during the excavation of the main tunnel, a second reinforcing ring beam is installed at the construction location, and the second reinforcing ring beam is fixedly connected to the second support structure.

[0015] Optionally, a second advanced small guide grouting zone is provided on the outer side of the arch of the second reinforcing ring beam.

[0016] Optionally, a third advanced small-diameter pipe grouting zone is provided between the first sub-tunnel and the second sub-tunnel.

[0017] Optionally, the first support structure and / or the second support structure is an I-beam structure, which includes multiple I-beams arranged horizontally and perpendicular to the direction of the transverse channel. The multiple I-beams are spaced apart and adjacent I-beams are connected by reinforcing bars. The surface of the I-beam structure is provided with a double-layer reinforcing mesh and sprayed with a layer of concrete.

[0018] This disclosure also provides a construction method for an auxiliary passage to enter a large-section tunnel intersection, including the following steps:

[0019] S1. Excavate a transverse passage and install a first support structure on the inner wall of the transverse passage;

[0020] S2. A gate structure is set in the transverse channel, and a first advanced small pipe grouting zone, a second advanced small pipe grouting zone and a third advanced small pipe grouting zone are set simultaneously.

[0021] S3. A gap is set in the first support structure at a position corresponding to the preset tunnel entrance, a second support structure is set at the gap, and the second support structure is connected to the first support structure;

[0022] S4. Excavate at the predetermined excavation locations of the first sub-tunnel and the second sub-tunnel, and install the first reinforcing ring beam; excavate at the predetermined excavation location of the main tunnel, and install the second reinforcing ring beam;

[0023] S5. The double-sidewall pilot tunnel method is used to carry out zoned excavation at the excavation location;

[0024] S6. Complete the excavation work of the main tunnel, the first sub-tunnel, and the second sub-tunnel.

[0025] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0026] The auxiliary passage provided in this disclosure enters the support structure of the large-section tunnel intersection, including a transverse passage. The extension direction of the transverse passage is perpendicular to the predetermined orientation of the tunnel. A first support structure is installed on the inner wall of the transverse passage to support the rock strata. To facilitate tunnel excavation, a gap is set at the position corresponding to the predetermined excavation location of the first support structure. A second support structure is installed at the gap. The connection between the second support structure and the first support structure provides support to the rock strata, and because the second support structure is a grid structure, it provides construction space for tunnel excavation. Furthermore, to improve the speed of tunnel excavation, the transverse passage is equipped with a first passage and a second passage arranged vertically to facilitate zoned excavation of the tunnel and improve tunnel construction efficiency. Door structures are installed at the ends of the first and second passageways, perpendicular to the extension direction of the transverse passageway. Both the first and second door frame supports within the door structures are connected to the first support structure via first support rods. Furthermore, at locations where door frame supports are not present, the door structures connect the opposite sides of the first support structure via second support rods. Therefore, the door structures provide support for the first support structures. Thus, by installing a first support structure within the transverse passageway, a second support structure at the notch in the first support structure, and a door structure perpendicular to the direction of the transverse passageway, a stable support structure is formed to support the transverse passageway. This improves the structural stability of the transverse passageway, avoids stress concentration issues, effectively reduces construction difficulty, and enhances construction safety. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0028] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the support structure for the auxiliary passage entering the intersection of a large-section tunnel as described in the embodiments of this disclosure;

[0030] Figure 2 This is a schematic diagram of the door structure described in an embodiment of this disclosure;

[0031] Figure 3 This is a schematic diagram of the support structure between the first and second sub-tunnels in an embodiment of this disclosure;

[0032] Figure 4 This is a schematic diagram of the first and second support structures in an embodiment of this disclosure;

[0033] Figure 5 This is a schematic diagram of the support structure at the main tunnel excavation location as described in an embodiment of this disclosure;

[0034] Figure 6 This is a partial structural diagram of the cross passage and tunnel described in an embodiment of this disclosure;

[0035] Figure 7 This is a schematic diagram of the first step of the double-sidewall guide tunnel method described in this embodiment of the present disclosure;

[0036] Figure 8 This is a schematic diagram of the second step of the double-sidewall guide tunnel method described in this embodiment of the present disclosure;

[0037] Figure 9 This is a schematic diagram of the third step of the double-sidewall guide tunnel method described in the embodiments of this disclosure;

[0038] Figure 10 This is a schematic diagram of the fourth step of the double-sidewall guide tunnel method described in this embodiment of the present disclosure;

[0039] Figure 11 This is a schematic diagram of the fifth step of the double-sidewall guide pit method described in the embodiments of this disclosure.

[0040] in:

[0041] 1. Cross passage; 2. First support structure; 3. Second support structure; 31. Central partition; 4. Gate structure; 41. First gate frame support; 42. Second gate frame support; 43. First support rod; 44. Second support rod; 45. Separation layer; 451. Reserved layer; 452. Steel frame concrete layer; 5. Main tunnel; 6. First sub-tunnel; 7. Second sub-tunnel; 8. First reinforcing ring beam; 9. Second reinforcing ring beam; 10. First advanced small pipe grouting zone; 20. Second advanced small pipe grouting zone; 30. Third advanced small pipe grouting zone; 40. Advanced grouting anchor pipe; 50. Drainage ditch; 60. Lower inverted arch concrete of the cross passage; 70. Horse-head gate area; 71. Horse-head gate expansion joint; 80. Excavation boundary line; 90. Fourth advanced small pipe grouting zone. Detailed Implementation

[0042] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0043] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0044] In one embodiment, such as Figures 1 to 6 As shown, a support structure for an auxiliary passage to enter a large-section tunnel intersection is provided, including a transverse passage 1. The extension direction of the transverse passage 1 is perpendicular to the predetermined direction of the tunnel. The transverse passage 1 includes a first passage and a second passage. The first passage and the second passage are arranged in a vertical direction, and the second passage is located above the first passage.

[0045] The first support structure 2 is set close to the inner wall of the cross passage 1, and a gap is formed in the first support structure 2 at the position corresponding to the preset tunnel opening.

[0046] The second support structure 3 is a grid structure and is located at the gap and connected to the first support structure 2.

[0047] The door structure 4 is located within the transverse passage 1 and is perpendicular to the extension direction of the transverse passage 1. It includes a first door frame support 41 for communicating with the first passage and a second door frame support 42 for communicating with the second passage. Both the first door frame support 41 and the second door frame support 42 are connected to the first support structure 2 through a first support rod 43. The door structure 4 also includes a plurality of second support rods 44 located above the first door frame support 41. Each second support rod 44 is parallel to the first support rod 43, and both ends of the second support rod 44 are connected to the first support structure 2.

[0048] The auxiliary passage provided in this embodiment enters the support structure of a large-section tunnel intersection, including a transverse passage 1. The extension direction of the transverse passage 1 is perpendicular to the predetermined orientation of the tunnel. A first support structure 2 is installed on the inner wall of the transverse passage 1 to support the rock strata. To facilitate tunnel excavation, a gap is provided at the position corresponding to the predetermined excavation location of the first support structure 2. A second support structure 3 is installed at the gap. The second support structure 3 connects with the first support structure 2, providing support to the rock strata. Since the second support structure 3 is a grid structure, it provides construction space for tunnel excavation. Furthermore, to improve the speed of tunnel excavation, the transverse passage 1 is provided with a first passage and a second passage arranged vertically to facilitate zoned excavation of the tunnel, thereby improving tunnel construction efficiency. A door structure 4 is installed at the ends of the first and second passages. The door structure 4 is perpendicular to the extension direction of the transverse passage 1. Both the first door frame support 41 and the second door frame support 42 in the door structure 4 are connected to the first support structure 2 via a first support rod 43. At locations in the door structure 4 where no door frame support is installed, the first support structures 2 on opposite sides are connected via a second support rod 44. Therefore, the door structure 4 provides support for the first support structure 2. Thus, by installing the first support structure 2 within the transverse passage 1, installing the second support structure 3 at the notch in the first support structure 2, and installing the door structure 4 at a location perpendicular to the direction of the transverse passage 1, a stable support structure for supporting the transverse passage 1 is formed. This improves the structural stability of the transverse passage 1, avoids stress concentration problems, effectively reduces construction difficulty, and improves construction safety.

[0049] Furthermore, by setting up the first door frame support 41 and the second door frame support 42 to form a passageway, it is convenient for construction personnel and construction vehicles to pass through, ensuring the efficiency of personnel and material transportation.

[0050] The aforementioned second support structure 3 includes multiple partitions 31, some of which are vertically arranged and some of which are horizontally arranged to form a grid structure.

[0051] Specifically, an advanced grouting anchor pipe 40 is installed above the aforementioned gate structure 4 to reinforce the tunnel arch, further enhance the support capacity, and ensure support safety. Below the gate structure 4 is a transverse passage lower inverted arch concrete 60, and a drainage ditch 50 is provided on the surface of the transverse passage lower inverted arch concrete 60 to facilitate the drainage of accumulated water in the transverse passage 1.

[0052] The aforementioned transverse passage 1, main tunnel 5, first sub-tunnel 6, and second sub-tunnel 7 are all constructed along the excavation boundary line 80. Specifically, the excavation boundary line 80 may include the tunnel excavation boundary line and the gate excavation boundary line. The transverse passage 1 is excavated along the gate excavation boundary line so that the transverse passage 1 is located in the gate area 70. The main tunnel 5, the first sub-tunnel 6, and the second sub-tunnel 7 all have gate expansion joints 71 at their connection points with the gate area 70.

[0053] Specifically, both the first support structure 2 and the second support structure 3 can be I-beam structures or grid steel frame structures. When the first support structure 2 is an I-beam structure, the surface of the I-beam structure is provided with a double-layer steel mesh and sprayed with concrete. Specifically, 22b I-beams are used. After removing the concrete protective layer of the inner wall of the transverse passage 1, a 1cm thick steel plate is welded to the steel grid of the transverse passage 1. The I-beams are spaced 50cm apart, and Φ22 steel bars are welded between the I-beams at 1m intervals, arranged alternately inside and outside. The double-layer steel mesh is Φ6.5, ​​and the sprayed C25 concrete is 30cm thick. When the second support structure includes multiple I-beams, some I-beams are arranged horizontally and some are arranged vertically, with multiple I-beams distributed at intervals, thus forming a grid-like structure for the second support structure 3.

[0054] As is easily understood, after the first support structure 2 is erected, it is sprayed with concrete to achieve a stable connection between the first support structure 2 and the cross passage 1.

[0055] Specifically, the fixed connection structure between the second support structure 3 and the first support structure 2 is not limited. It can be connected by bolts or clips, etc. The most important thing is to meet the mechanical requirements of the support. For example, the second support structure 3 can be welded to the first support structure 2.

[0056] Specifically, a partition layer 45 may be provided between the first door frame support 41 and the second door frame support 42. The partition layer 45 includes a reserved layer 451 and a steel frame concrete layer 452 set above the reserved layer 451. The steel frame concrete layer 452 includes a steel frame, which is connected to the first support structure 2.

[0057] During the construction of the first and second passages, rock strata were left in both passages to serve as the ground surface for the second passage. To ensure the load-bearing capacity of this layer and the convenience of vehicle traffic, a steel-framed concrete layer 452 was installed on the rock strata. During construction, a steel frame was installed above the rock strata as the reserved layer 451, with both ends of the steel frame connected to the first support structure 2. Concrete was then laid on top of the steel frame to connect it to the reserved layer 451, thereby improving the structural strength of the partition layer 45 and ensuring a high degree of flatness on the ground surface of the second passage, facilitating vehicle traffic.

[0058] In some embodiments, reference is made to Figure 1 The transverse passage 1 is located between the main tunnel 5 and the first and second sub-tunnels 6 and 7. Specifically, the main tunnel 5 is located on one side of the transverse passage 1, and the first and second sub-tunnels are located on the opposite side, with the first and second sub-tunnels 6 and 7 adjacent to each other. The first and second sub-tunnels can be used as connecting tunnels, etc.

[0059] Specifically, the first support structure 2 includes at least two notches, which are respectively set to correspond to the first sub-tunnel 6 and the second sub-tunnel 7. A second support structure 3 is set at each notch to ensure the support function of the cross passage 1.

[0060] In some embodiments, when excavating the first sub-tunnel 6 and the second sub-tunnel 7, a first reinforcing ring beam 8 is provided at a predetermined position of the first sub-tunnel 6 and the second sub-tunnel 7. The first reinforcing ring beam 8 is located on the outside of the first sub-tunnel 6 and the second sub-tunnel 7, and the first reinforcing ring beam 8 is connected to the second support structure 3.

[0061] The first and second sub-tunnels are surrounded by an integral support structure. It should be noted that this essentially involves supporting the first and second sub-tunnels to protect the rock strata at their locations and ensure construction safety. Furthermore, by connecting the first reinforcing ring beam 8 to the second support structure 3, the stability of the second support structure 3's installation is improved, and the overall strength of the support structure is also increased.

[0062] When the main tunnel 5 is excavated, the first support structure 2 includes a gap corresponding to the main tunnel 5, and a second support structure 3 is installed at the gap.

[0063] During the excavation of the main tunnel 5, a second reinforcing ring beam 9 was installed at the construction location, and the second reinforcing ring beam 9 was fixedly connected to the second support structure 3. (Refer to...) Figure 5 A second reinforcing ring beam 9 is installed at the location corresponding to the main tunnel 5. Furthermore, the second reinforcing ring beam 9 is connected to the second support structure 3 to form a unified support structure, further enhancing the support capacity and ensuring support safety. The second reinforcing ring beam 9 and the second support structure can support the tunnel, share the vertical pressure of the first support structure 2, and ensure the support strength of the support structure.

[0064] Additionally, refer to Figure 3 and Figure 4 A first advanced small-diameter pipe grouting zone 10 can be provided on the outer side of the arch crown of the first reinforcing ring beam 8, and a second advanced small-diameter pipe grouting zone 20 can be provided on the outer side of the arch crown of the second reinforcing ring beam 9. The advanced small-diameter pipe grouting zones can reinforce the tunnel arch crown, further enhance the support capacity, and ensure support safety.

[0065] In addition, a fourth advanced small pipe grouting zone 90 can be set above the second tunnel 7 to reinforce the tunnel arch, further enhance the support capacity, and ensure support safety.

[0066] Furthermore, refer to Figure 6 A third advanced small-diameter pipe grouting zone 30 is provided between the first and second sub-tunnels. Since the first and second sub-tunnels are relatively close, an advanced small-diameter pipe grouting zone is constructed between them to prevent anomalies in the tunnel walls. This enhances the load-bearing capacity of the tunnel walls and ensures safety. Furthermore, to further improve the load-bearing capacity of the tunnel walls, when setting the first support structure 2 in the cross passage 1, the first support structures 2 at the predetermined locations of the two tunnels can be designed to be more densely packed to improve support capacity and ensure safety.

[0067] Specifically, the dimensions of the first door frame bracket 41 and the second door frame bracket 42 are not limited and can be designed as 3m × 2.5m.

[0068] Specifically, the gate structure 4 is set between the preset excavation position of the tunnel and the beginning of the cross passage 1 to ensure that the preset excavation position is excavated in layers to improve efficiency.

[0069] Furthermore, reinforcement structures are provided at the edges of the first door frame support 41 and the second door frame support 42 to improve structural stability. For example, 22b I-beams and 1cm thick steel plates are used to reinforce the outer sides of the first door frame support 41 and the second door frame support 42.

[0070] It should be noted that the above solution is for large-section tunnels, but is not limited to scenarios containing only large-section tunnels.

[0071] In another embodiment, a construction method for an auxiliary passage to enter a large-section tunnel intersection is provided, comprising the following steps:

[0072] S1. Excavate the transverse passage 1 and install the first support structure 2 on the inner wall side of the transverse passage 1.

[0073] Specifically, the first support structure 2 is an arch-top straight-wall lining structure, using a combination of lattice steel frame + pre-grouting anchor pipe + steel mesh + shotcrete support. A temporary invert arch is provided for both the upper and lower guide tunnels of the auxiliary passage, with a shotcrete thickness of 0.3m. Earthwork excavation is done manually, with an excavation advance of 0.5m. Temporary steel supports are installed at the designed locations during initial support. The annular core soil is reserved for at least 1 / 3 of the arch cross-sectional area, with a length controlled at approximately 3m. The distance between the core soil and the initial support on both sides is approximately 1.0m. The length of the upper step is controlled at approximately 5.0m. Strict monitoring and measurement are conducted during construction, and design parameters are adjusted based on the measurement results. Excavation of "fairy soil" is strictly prohibited during excavation; excavation proceeds layer by layer from top to bottom. The slope of the soil at the lower step face is approximately 1:0.8. When excavating the next section of earthwork, the soil attached to the reinforcing bars and mesh of the previous section must be thoroughly cleaned, especially the soil or sandbags inside the grid at the arch foot. No dead corners should be left, otherwise the shotcrete will form voids or be not dense.

[0074] S2. Set a door structure 4 inside the transverse passage 1.

[0075] S3. A gap is set in the first support structure 2 at a position corresponding to the preset tunnel entrance. A second support structure 3 is set at the gap and connected to the first support structure 2. The first advanced small pipe grouting zone 10, the second advanced small pipe grouting zone 20 and the third advanced small pipe grouting zone 30 are set simultaneously.

[0076] Specifically, the second support structure 3 is primarily constructed using 22b I-beams. After removing the concrete protective layer from the sidewalls of the auxiliary passage, 1cm thick steel plates are welded to the auxiliary passage's grid. The I-beams are spaced 50cm vertically and connected by Φ22 steel bars at 1m intervals, arranged in an alternating pattern. A double-layer Φ6.5 steel mesh is laid on the surface of the second support structure 3, and 30cm thick C25 concrete is sprayed onto it. Strict quality control is maintained during the construction of the second support structure 3 to ensure a tight fit with the auxiliary passage's invert and arch, and a reliable connection with the sidewall steel grid.

[0077] Specifically, when constructing the first advanced small-diameter guide grouting zone 10, double-row Φ42×3.25 advanced small-diameter guides were used for reinforcement, with a guide length L = 5m. The circumferential spacing was 300mm, and the horizontal inclination angle was 10 to 15°.

[0078] Specifically, when constructing the third advanced small-diameter pipe grouting zone 30, Φ42×3.25 advanced small-diameter pipes are used for reinforcement, with a pipe length L=5m. Four pipes are erected horizontally and evenly distributed; the vertical spacing between the pipes is 1.0m, and the vertical reinforcement range is 1.0m above and below the tunnel excavation height.

[0079] S4. Excavate at the predetermined excavation locations of the first sub-tunnel 6 and the second sub-tunnel 7, and install the first reinforcing ring beam 8; excavate at the predetermined excavation location of the main tunnel 5, and install the second reinforcing ring beam 9.

[0080] Specifically, the reinforcing ring beams need to be constructed in sections according to the tunnel construction process to ensure the stability of the soil and rock strata around the tunnel. The first reinforcing ring beam 8 and the second reinforcing ring beam 9, along with the second support structure 3, can all share the load of the first support structure 2.

[0081] S5. The double-side-wall pilot tunnel method is used to carry out zoned excavation at the excavation location.

[0082] Specifically, due to the large tunnel span, the double-side-wall pilot tunnel method was adopted for underground excavation. Furthermore, since the cross passage 1 is located between the main tunnel 5 and the sub-tunnels, the main tunnel 5, the first sub-tunnel 6, and the second sub-tunnel 7 can be excavated simultaneously.

[0083] S6. Complete the excavation work on the main tunnel 5, the first sub-tunnel 6, and the second sub-tunnel 7.

[0084] Reference Figures 7 to 11 The image shows a schematic diagram of tunnel excavation using the pilot tunnel method. (Refer to...) Figure 8 After creating a gap by partially breaking through the first support structure 2 and passing inspection, the step method was used to excavate tunnel ①-1. (Refer to...) Figure 9 After tunnel ①-1 has been excavated for 3-5m, tunnel ①-2 will be excavated using the bench method, maintaining a step distance of 3-5m. When descending the bench, the upper diaphragm of the corresponding transverse passage will be removed. (Refer to...) Figure 10 Excavation of tunnel ② should be carried out sequentially using the step method, maintaining a distance of one tunnel diameter from tunnel ①. Tunnel ②-1 should be excavated first, with tunnel ②-2 maintaining a step distance of 3-5 meters from ②-1. When constructing the lower steps, the lower layer diaphragm of the corresponding transverse passage should be removed. (Refer to...) Figure 11 The tunnel ③ and tunnel ②, and tunnel ④ and tunnel ③ are excavated using the step method with a diameter of 1, and the corresponding diaphragm within the tunnel area is removed during construction.

[0085] During the demolition of the first support structure, the second support structure should be constructed promptly, and anchor pipes should be installed. After the upper step arch has settled and stabilized, the lower step gate should be constructed. The excavation length of the upper step inside the tunnel should be controlled at 5-6m, and the staggered length between adjacent steps should be determined according to the tunnel dimensions. After the gate area is fully constructed and the tunnel section is entered, three reinforced grids for the tunnel section should be densely arranged at the opening, with a grid spacing of 0.5m / grid within 3m of the tunnel.

[0086] Anchor bolts: Anchor bolts are installed at the arch foot of the excavation step and driven into the surrounding rock at a 30-45° angle to the vertical direction to control the subsidence of the arch foot.

[0087] Steel frame support construction quality standards: The assembly deviation along the perimeter of the steel grid frame shall not exceed ±30mm; the center-to-center distance of bolt holes shall not exceed ±0.5mm; when the steel grid frame is laid flat, the warping shall not exceed ±20mm, the tilt shall not exceed 2°, and any part of the steel grid frame shall not deviate from the vertical plane by more than 50mm; the steel grid frame shall be erected in a plane perpendicular to the tunnel axis, with allowable deviations of: lateral ±30mm, longitudinal ±50mm, elevation ±30mm, and verticality 5‰.

[0088] When constructing the pre-grouting small guide pipes, first drill holes with a coal-fired electric drill, insert the small guide pipes, and vibrate them in with a pneumatic hammer. The circumferential spacing is 300mm, the outward inclination angle is 15-20°, and the longitudinal horizontal overlap length of the small guide pipes is ≥1m. Do not drill within 50cm of the tail of the pre-grouting small guide pipe to prevent grout leakage. Weld a Ф6 ring-shaped stirrup to the end to prevent cracking at the end of the small guide pipe during installation, which would affect the connection of the grouting pipe. Strictly control the mix ratio and gel time for small guide pipe grouting. After initially selecting the mix ratio, adjust it using gel time control and measure the strength of the grout solidified body to select the optimal mix ratio. During grouting, strictly control the grouting pressure. The final grouting pressure must meet the design requirements and be stabilized for 1-2 minutes to ensure the penetration range of the grout.

[0089] Escape tunnels shall be constructed using φ800mm steel pipes with a wall thickness of not less than 1cm and a length of not less than 100m. The starting point shall be 1-2m away from the working face, and escape tunnels shall be constructed at the upper and lower steps of the working face.

[0090] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0091] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A support structure for an auxiliary passage entering a large-section tunnel intersection, characterized in that, include: A transverse passage (1) extends in a direction perpendicular to the predetermined direction of the tunnel. The transverse passage (1) includes a first passage and a second passage. The first passage and the second passage are arranged in a vertical direction, and the second passage is located above the first passage. The first support structure (2) is located close to the inner wall of the transverse passage (1), and a gap is formed in the first support structure (2) at a position corresponding to the preset tunnel entrance. The second support structure (3) is a grid structure. The second support structure (3) is set at the gap and connected to the first support structure (2). The second support structure (3) includes multiple partitions (31). Some of the partitions (31) are set vertically and some of the partitions (31) are set horizontally to form a grid structure. The grid structure continuously covers multiple gaps. The door structure (4) is located in the transverse passage (1) and is perpendicular to the extension direction of the transverse passage (1). It includes a first door frame bracket (41) for communicating with the first passage and a second door frame bracket (42) for communicating with the second passage. The first door frame bracket (41) and the second door frame bracket (42) are both connected to the first support structure (2) through a first support rod (43). The door structure (4) also includes a plurality of second support rods (44) located above the first door frame bracket (41). Each second support rod (44) is parallel to the first support rod (43), and both ends of the second support rod (44) are connected to the first support structure (2).

2. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to claim 1, characterized in that, A partition layer (45) is provided between the first door frame support (41) and the second door frame support (42). The partition layer (45) includes a reserved layer (451) and a steel frame concrete layer (452) set above the reserved layer (451). The steel frame concrete layer (452) includes a steel frame, which is connected to the first support structure (2).

3. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to claim 2, characterized in that, The large-section tunnel includes a main tunnel (5) and a first sub-tunnel (6) and a second sub-tunnel (7) that are both connected to the main tunnel (5). The first sub-tunnel (6) and the second sub-tunnel (7) are arranged adjacent to each other. The cross passage (1) is located between the main tunnel (5) and the first sub-tunnel (6) and the second sub-tunnel (7). The first support structure (2) includes at least two gaps, which are respectively arranged to correspond to the first sub-tunnel (6) and the second sub-tunnel (7). A second support structure (3) is provided at each gap.

4. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to claim 3, characterized in that, When excavating the first sub-tunnel (6) and the second sub-tunnel (7), a first reinforcing ring beam (8) is provided at a preset position of the first sub-tunnel (6) and the second sub-tunnel (7). The first reinforcing ring beam (8) is located outside the first sub-tunnel (6) and the second sub-tunnel (7), and the first reinforcing ring beam (8) is connected to the second support structure (3).

5. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to claim 4, characterized in that, The first advanced small guide grouting zone (10) is provided on the outer side of the arch of the first reinforcing ring beam (8).

6. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to claim 3, characterized in that, The first support structure (2) also includes a notch corresponding to the main tunnel (5), and the second support structure (3) is provided at the notch.

7. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to claim 6, characterized in that, During the excavation of the main tunnel (5), a second reinforcing ring beam (9) is installed at the construction location, and the second reinforcing ring beam (9) is fixedly connected to the second support structure (3).

8. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to claim 7, characterized in that, The second reinforcing ring beam (9) has a second advanced small pipe grouting zone (20) on the outer side of the arch.

9. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to claim 3, characterized in that, A third advanced small pipe grouting zone (30) is provided between the first sub-tunnel and the second sub-tunnel.

10. The support structure for the auxiliary passage entering the intersection of a large-section tunnel according to any one of claims 1 to 9, characterized in that, The first support structure (2) and / or the second support structure (3) are I-beam structures. The I-beam structure includes multiple I-beams. The I-beams are arranged horizontally and perpendicular to the direction of the transverse channel (1). The multiple I-beams are distributed at intervals. Adjacent I-beams are connected by steel bars. The surface of the I-beam structure is provided with a double-layer steel mesh and sprayed with a layer of concrete.

11. A construction method for an auxiliary passage entering a large-section tunnel intersection, characterized in that, The steps include the following: S1. Excavate the transverse passage (1) and set the first support structure (2) on the inner wall side of the transverse passage (1); S2. A door structure (4) is provided in the transverse passage (1); S3. A gap is set in the first support structure (2) at a position corresponding to the preset tunnel opening, a second support structure (3) is set at the gap, and the second support structure (3) is connected to the first support structure (2), and a first advanced small pipe grouting area (10), a second advanced small pipe grouting area (20) and a third advanced small pipe grouting area (30) are set simultaneously. S4. Excavate at the preset excavation locations of the first sub-tunnel (6) and the second sub-tunnel (7) and set up the first reinforcing ring beam (8); excavate at the preset excavation location of the main tunnel (5) and set up the second reinforcing ring beam (9). S5. The double-sidewall pilot tunnel method is used to carry out zoned excavation at the excavation location; S6. Based on the step excavation method, complete the excavation work of the main tunnel (5), the first sub-tunnel (6), and the second sub-tunnel (7), and remove the upper middle partition of the cross passage at the corresponding position when constructing the step, and remove the lower middle partition of the cross passage at the corresponding position when constructing the step, and remove the corresponding middle partition in sequence within the excavation range during construction.

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