Steel arch support arch foot fixing device suitable for loess tunnel and construction method thereof

Abstract

The present application relates to a steel arch support arch foot fixing device suitable for loess tunnel and a construction method thereof. At present, there are problems of space conflict with reserved core soil and easy to cause instability or collapse of the working face when fixing the steel arch support arch foot. The present application comprises a plurality of lock foot anchor pipes and a plurality of guide fixed steel plates. The two side flange plates of the steel frame are respectively provided with guide fixed steel plates, the guide fixed steel plates are distributed in multiple groups on the steel frame, each group is provided with two guide fixed steel plates, the two guide fixed steel plates are respectively arranged on the flange plates on both sides of the steel frame, and the two guide fixed steel plates of each group are asymmetrically distributed, the guide fixed steel plate on one side flange plate is close to the inner side of the tunnel, and the guide fixed steel plate on the other side flange plate is close to the surrounding rock side. The lock foot anchor pipe is arranged on the guide fixed steel plate and is inclined forward. The present application can effectively avoid the core soil, avoid the space conflict between the mechanical arm and the core soil, and ensure the stability of the working face and the construction safety.

Description

Technical Field

[0001] This invention relates to the field of tunnel and underground engineering support technology, specifically to a steel arch frame arch foot fixing device and its construction method suitable for loess tunnels. Background Technology

[0002] In the excavation and construction of loess tunnels, the stability control of the tunnel face is one of the core issues to ensure construction safety and progress. To control the stability of the tunnel face, the current common practice is to use the sectional excavation method and reserve core soil. The area of ​​the core soil usually accounts for 30% to 50% of the tunnel face area. This approach provides passive support to the tunnel face through the core soil, effectively slowing down the stress release rate of the surrounding rock and inhibiting the extrusion deformation of the tunnel face. It is a key stabilization measure in the construction of loess tunnels.

[0003] In traditional construction methods, after the upper-step steel frame is erected, manual hand-held pneumatic guns are typically used to install anchor pipes (such as φ42mm small guide pipes) to constrain the displacement of the steel frame arch feet and improve the stability of the initial support structure. However, with the nationwide advancement of mechanized construction across all railway tunnel projects, the manual hand-held pneumatic gun operation has revealed many drawbacks: First, workers are exposed to the unsupported tunnel face area for extended periods, posing safety risks such as arch top collapse and tunnel face collapse; second, pneumatic gun operation is labor-intensive and inefficient, making it difficult to meet the requirements of mechanized rapid-cycle construction; third, when encountering soft loess layers with high water content, the anchor feet need to be reinforced with pipe roofs with a diameter of 89mm, which the pneumatic gun cannot meet the drilling requirements for this diameter and depth, necessitating the use of down-the-hole drilling rigs.

[0004] Down-the-hole (DH) drilling rigs have advantages such as large drilling diameter, high drilling efficiency, and good hole quality, which can meet the construction needs of large-diameter anchor pipe sheds. However, the DH drilling rig has a long drilling arm, which causes significant spatial conflict with the reserved core soil when drilling anchor pipes. The drilling arm cannot bypass the core soil to approach the designed hole position of the arch foot, making it difficult to carry out the anchor construction according to the designed position and angle.

[0005] To resolve the aforementioned spatial conflict, two main measures are currently being taken on-site: the first is to reduce the size of the core soil or eliminate it altogether to provide working space for the drilling rig; the second is to postpone the anchoring construction to the next cycle, and then carry out supplementary drilling after the core soil has been excavated and removed. However, both measures have significant drawbacks: reducing or eliminating the core soil will weaken its supporting effect on the tunnel face, leading to increased extrusion deformation of the tunnel face, and even causing instability or collapse of the tunnel face; postponing the anchoring construction will prevent the steel frame arch foot from being locked in time, leaving the initial support structure in an under-restrained state in the early stages, which also increases the risk of collapse.

[0006] Therefore, it is necessary to propose new measures to overcome the above-mentioned shortcomings. Summary of the Invention

[0007] The purpose of this invention is to provide a steel arch frame arch foot fixing device and its construction method suitable for loess tunnels, so as to at least solve the problems of spatial conflict between the steel arch frame arch foot fixing and the reserved core soil, and the easy occurrence of instability or collapse of the tunnel face.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A steel arch frame arch foot fixing device suitable for loess tunnels, including multiple locking anchor pipes and multiple guide fixing steel plates;

[0010] The guide fixing steel plates are distributed in multiple groups on the steel frame, with two guide fixing steel plates in each group. The two guide fixing steel plates are respectively set on the flange plates on both sides of the steel frame, and the two guide fixing steel plates in each group are asymmetrically distributed. The guide fixing steel plates on one flange plate are closer to the inner side of the tunnel, and the guide fixing steel plates on the other flange plate are closer to the surrounding rock side.

[0011] The locking foot anchors are respectively set on the guide fixing steel plate, and are all installed at an angle forward. The length of the locking foot anchors is extended.

[0012] Furthermore, the angle between the anchor pipe and the horizontal plane is a preset downward angle, and the horizontal projection of the anchor pipe forms an acute angle with the tunnel axis direction.

[0013] Furthermore, the length of the guide fixing steel plate is greater than the width of the flange plate, the guide fixing steel plate is partially attached to the flange plate, and the excess part of the guide fixing steel plate is exposed on one side.

[0014] Furthermore, the exposed portion of the guide fixing steel plate near the surrounding rock faces away from the tunnel face, while the exposed portion of the guide fixing steel plate near the tunnel interior faces towards the tunnel face.

[0015] Furthermore, the center of the exposed portion of the guide fixing steel plate is provided with guide fixing holes, and the locking foot anchor tube is disposed in the guide fixing holes.

[0016] Furthermore, the diameter of the guide fixing hole is larger than the diameter of the locking foot anchor tube.

[0017] Furthermore, the edges of the guide fixing holes are respectively provided with reinforcing fixing structures.

[0018] Furthermore, the reinforcing fixing structure includes multiple short steel bars, which are respectively disposed at the upper and lower edges of the guide fixing hole, and one side of the short steel bar is fixed to the guide fixing steel plate, and the other side is fixed to the locking foot anchor pipe.

[0019] Furthermore, let the length of the anchor pipe installed perpendicular to the tunnel axis in the original design be L, and the horizontal angles between the anchor pipe and the tunnel vertical are respectively... and The length of the extended anchor pipe is then... , They respectively satisfy: , .

[0020] The construction method for the steel arch frame arch foot fixing device applicable to loess tunnels described above includes the following steps:

[0021] According to the design requirements, the steel frame is processed, and multiple sets of guide and fixing steel plates are set asymmetrically on the two side flanges of the steel frame, and the position of the guide and fixing holes is ensured to be accurate.

[0022] After one cycle of tunnel excavation, a steel frame with guide and fixing steel plates is erected, and the core soil is preserved;

[0023] According to the forward-sloping design angle, a down-the-hole drill is used to pass the anchor pipe through the guide fixing hole of the guide fixing steel plate and drill it to the extended design length.

[0024] Fix the anchor pipe to the guide fixing steel plate and set short steel bars at the guide fixing holes;

[0025] Repeat the above steps to complete the construction of all anchor pipes.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention provides a steel arch support foot fixing device and its construction method suitable for loess tunnels. It includes a foot anchor pipe and a guide fixing steel plate. By asymmetrically welding guide fixing steel plates with guide fixing holes onto the flange plates of the steel frame, and then obliquely driving the foot anchor pipe forward onto the guide fixing steel plate, the device effectively avoids the core soil. This avoids spatial conflict between the robotic arm and the core soil without eliminating the reserved core soil, ensuring the stability of the tunnel face and construction safety. Furthermore, by lengthening the foot anchor pipe, horizontal convergence control is maintained, and short reinforcing bars are added at the connection between the foot anchor pipe and the guide fixing steel plate for reinforcement welding, thus ensuring the reliability of the support structure. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a top view of Example 1 applied to a construction site;

[0030] Figure 2 This is a front view of the working face of Embodiment 1;

[0031] Figure 3 This is a top-view enlarged view of Example 1;

[0032] Figure 4 This is a detailed drawing of the guide fixing steel plate and short reinforcing bars in Example 1;

[0033] The diagram is labeled as follows:

[0034] 1-Steel frame, 2-Anchor pipe, 3-Guide fixing steel plate, 4-Flange plate, 5-Short steel bar, 6-Guide fixing hole, 7-Core soil. Detailed Implementation

[0035] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0036] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] In the description of this invention, it should be understood that the method involves multiple steps and should not be construed as a limitation on the order of the steps. Technical solutions obtained by changing the order of steps when solving the same technical problem are also within the protection scope of this invention.

[0039] Example 1:

[0040] This embodiment provides a steel arch frame arch foot fixing device suitable for loess tunnels, including multiple locking anchor pipes 2 and multiple guide fixing steel plates 3.

[0041] Specifically, the guide fixing steel plates 3 are distributed in multiple groups on the steel frame 1. Each group has two guide fixing steel plates 3. The two guide fixing steel plates 3 are respectively set on the flange plates 4 on both sides of the steel frame 1. The two guide fixing steel plates 3 in each group are asymmetrically distributed. The guide fixing steel plates 3 on one flange plate 4 are closer to the inner side of the tunnel, and the guide fixing steel plates 3 on the other flange plate 4 are closer to the surrounding rock side.

[0042] Among them, the steel frame 1 is an I-beam, the guide fixing steel plate 3 is a cuboid, the length of the guide fixing steel plate 3 is greater than the width of the flange plate 4, the guide fixing steel plate 3 is partially welded to the flange plate 4, the excess part of the guide fixing steel plate 3 is exposed, and the length of the excess part of the guide fixing steel plate 3 is greater than the diameter of the locking foot anchor pipe 2.

[0043] In this embodiment, the thickness of the guide fixing steel plate 3 is 6mm, the length is 150mm longer than the width of the flange plate 4, the width of the guide fixing steel plate 3 is 150mm, the part of the guide fixing steel plate 3 that is attached to the flange plate 4 is fully welded firmly, and the extra 150mm length of the guide fixing steel plate 3 is only exposed on one side.

[0044] To ensure convenient construction and reasonable structural stress, the guide fixing steel plates 3 on the two flange plates 4 are welded asymmetrically. The exposed part of the guide fixing steel plate 3 near the surrounding rock faces away from the tunnel face, while the exposed part of the guide fixing steel plate 3 near the tunnel interior faces towards the tunnel face.

[0045] In this embodiment, the center of the exposed part of the guide fixing steel plate 3 is provided with guide fixing holes 6, and the locking foot anchor pipe 2 is set in the guide fixing holes 6. The guide fixing holes 6 are used to guide and fix the locking foot anchor pipe 2.

[0046] One end of the anchor pipe 2 is welded and fixed in the guide fixing hole 6 of the guide fixing steel plate 3, and the anchor pipe 2 is installed at an angle to the front to avoid the reserved core soil 7. The length of the anchor pipe 2 is extended.

[0047] Specifically, the angle between the anchor pipe 2 and the horizontal plane is a preset downward angle, and the horizontal projection of the anchor pipe 2 forms an acute angle with the tunnel axis direction.

[0048] The diameter of the guide fixing hole 6 is larger than the diameter of the locking foot anchor tube 2, which makes it easier for the locking foot anchor tube 2 to be placed obliquely in the guide fixing hole 6.

[0049] In this embodiment, a guide fixing steel plate 3 with guide fixing holes 6 is asymmetrically welded on the flange plate 4 of the steel frame 1, and the locking foot anchor pipe 2 is obliquely driven forward on the guide fixing steel plate 3 to effectively avoid the core soil 7. Thus, without canceling the reserved core soil 7, the spatial conflict between the robotic arm and the core soil 7 is avoided, ensuring the stability of the working face and construction safety.

[0050] Specifically, the edges of the guide fixing holes 6 are respectively provided with reinforcing fixing structures, which include two short steel bars 5. The short steel bars 5 are non-linear and their length is greater than the diameter of the guide fixing holes 6. The short steel bars 5 are respectively set at the upper and lower edges of the guide fixing holes 6. The middle part of the short steel bars 5 fits into the edge of the guide fixing holes 6 in an arc shape. One side of the short steel bars 5 is welded and fixed to the guide fixing steel plate 3, and the other side is welded and fixed to the locking foot anchor pipe 2, so that the locking foot anchor pipe 2, the short steel bars 5 and the guide fixing steel plate 3 form a whole, further strengthening the fixation of the locking foot anchor pipe 2. In this embodiment, the length of the short steel bars 5 is 15cm.

[0051] To compensate for the reduced horizontal convergence control due to the shortened effective horizontal projection length caused by the forward-angled installation, the length of anchor pipe 2 needs to be increased. Let the original design length of the anchor pipe installed perpendicular to the tunnel axis be L, and the horizontal angles between anchor pipe 2 and the tunnel vertical be... and The length of the extended anchor pipe 2 is then... , They respectively satisfy: , .

[0052] In this embodiment, the length of the extended anchor pipe 2 is calculated using a length compensation formula to maintain horizontal convergence control capability. Short steel bars 5 are added at the connection between the anchor pipe 2 and the guide fixing steel plate 3 for reinforcement welding to ensure the reliability of the support structure.

[0053] This embodiment features a simple structure, low modification cost, and convenient construction operation. It is particularly suitable for loess tunnels using large machinery such as down-the-hole drills for anchoring. Asymmetrical guide and fixing steel plates 3 are welded onto the steel frame 1, and anchoring pipes 2 are driven obliquely forward onto the guide and fixing steel plates 3, effectively avoiding the core soil 7. This prevents spatial conflict between the robotic arm and the core soil 7, ensuring the stability of the tunnel face and construction safety. Simultaneously, the length of the anchoring pipes 2 is increased to maintain horizontal convergence control, and short reinforcing bars 5 are added at the connection between the anchoring pipes 2 and the guide and fixing steel plates 3 to ensure the reliability of the support structure. This embodiment achieves timely and mechanized anchoring construction without eliminating the core soil 7, significantly improving the safety and efficiency of loess tunnel construction, and has high practical value and promising prospects for wider application.

[0054] Example 2:

[0055] This embodiment provides a construction method for a steel arch frame arch foot fixing device suitable for loess tunnels, including the following steps:

[0056] S1: Process the steel frame 1 according to the design requirements, and weld multiple sets of guide and fixing steel plates 3 on the two side flange plates 4 of the steel frame 1 in an asymmetrical manner, and ensure that the guide and fixing holes 6 are in accurate positions.

[0057] S2: After one cycle of tunnel excavation, a steel frame 1 with guide and fixing steel plates 3 is erected, and the core soil 7 is retained.

[0058] S3: According to the forward-sloping design angle, use a down-the-hole drill to pass the anchor pipe 2 through the guide fixing hole 6 of the guide fixing steel plate 3 and drill to the extended design length.

[0059] S4: Fix the anchor pipe 2 to the guide fixing steel plate 3, and set the short steel bar 5 at the guide fixing hole 6.

[0060] Weld one end of the anchor pipe 2 to the guide fixing steel plate 3 at the guide fixing hole 6. Then weld a 15cm short steel bar 5 to the upper and lower edges of the guide fixing hole 6. Weld the guide fixing steel plate 3 to one side of the short steel bar 5 and the anchor pipe 2 to the other side.

[0061] S5: Repeat the above steps to complete the construction of all anchor pipes 2.

[0062] Example 3:

[0063] This embodiment takes a Class IV surrounding rock section of a loess tunnel as an example. The design adopts I20b type steel frame 1. The original anchor pipe is designed as a φ42mm small guide pipe with a length L=4.0m and an angle of 45° with the horizontal plane, and is installed perpendicular to the tunnel axis.

[0064] To accommodate down-the-hole drilling rig construction and preserve the core soil 7, the solution of this invention is adopted as follows:

[0065] A 6mm thick guide fixing steel plate 3 is welded to each of the two flange plates 4 of the steel frame 1. The exposed part of the outer guide fixing steel plate 3 faces backward (away from the working face), and the exposed part of the inner guide fixing steel plate 3 faces forward (close to the working face). The dimensions of the guide fixing steel plate 3 are: length = flange plate width (about 85mm) + 150mm = 235mm, width is 150mm, and the exposed 150mm length part has a φ50mm guide fixing hole 6 reserved at the center of the guide fixing steel plate 3.

[0066] Maintaining a downward inclination angle of 45° to the horizontal plane, the angle between the horizontal projection and the tunnel axis is designed to be 60° (i.e., the horizontal angle with the tunnel's vertical line). ).

[0067] Length compensation calculation: Taking 4.6m, we can obtain the following similarly. =4.6m.

[0068] The construction method and steps are as follows:

[0069] S1: Process the steel frame 1 according to the design requirements, and weld the guide fixing steel plate 3 on the two side flange plates 4 of the steel frame 1 in an asymmetrical manner, and ensure that the guide fixing hole 6 is in the correct position.

[0070] S2: After one cycle of tunnel excavation, erect an I20b type steel frame 1 with guide and fixing steel plate 3, and retain the core soil 7.

[0071] S3: The down-the-hole drill is positioned, and the drill arm is driven through the guide fixing hole 6 at a 30° angle forward and a 45° downward angle to install the φ42mm anchor pipe 2, with a single length of 4.6m.

[0072] S4: Fix the anchor pipe 2 to the guide fixing steel plate 3, and set the short steel bar 5 at the guide fixing hole 6.

[0073] One end of the locking foot anchor pipe 2 is spot welded to the guide fixing steel plate 3 at the guide fixing hole 6. Then, a short steel bar 5 with a diameter of 12mm and a length of 15cm is welded to the upper and lower edges of the guide fixing hole 6. The guide fixing steel plate 3 is welded to one side of the short steel bar 5, and the locking foot anchor pipe 2 is welded to the other side.

[0074] S5: Repeat the above steps to complete the construction of all anchor pipes 2.

[0075] In this embodiment, the locking foot did not interfere with the core soil 7, achieving timely support. The effective vertical length projection is 4.6×sin45°≈3.25m, which is an improvement compared to the original design of 4.0×sin45°≈2.83m. The effective horizontal projection length is 4.6×cos45°×cos30°≈2.83m, which is the same as the original design of 4.0×sin45°≈2.83m. Therefore, the ability of this invention to control vertical settlement and horizontal convergence is no less than that of the original design.

[0076] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A steel arch frame arch foot fixing device suitable for loess tunnels, characterized in that: It includes multiple locking foot anchor pipes (2) and multiple guide fixing steel plates (3); The guide fixing steel plates (3) are distributed in multiple groups on the steel frame (1). Each group has two guide fixing steel plates (3). The two guide fixing steel plates (3) are respectively set on the flange plates (4) on both sides of the steel frame (1). The two guide fixing steel plates (3) in each group are asymmetrically distributed. The guide fixing steel plates (3) on one side of the flange plate (4) are closer to the inner side of the tunnel, and the guide fixing steel plates (3) on the other side of the flange plate (4) are closer to the surrounding rock side. The locking foot anchor pipes (2) are respectively set on the guide fixing steel plate (3), and are all installed at an angle forward. The length of the locking foot anchor pipes (2) is extended.

2. The steel arch frame arch foot fixing device for loess tunnels according to claim 1, characterized in that: The angle between the anchor pipe (2) and the horizontal plane is a preset downward angle, and the horizontal projection of the anchor pipe (2) forms an acute angle with the tunnel axis direction.

3. The steel arch frame arch foot fixing device for loess tunnels according to claim 1, characterized in that: The length of the guide fixing steel plate (3) is greater than the width of the flange plate (4). The guide fixing steel plate (3) is partially attached to the flange plate (4), and the excess part of the guide fixing steel plate (3) is exposed on one side.

4. The steel arch frame arch foot fixing device for loess tunnels according to claim 3, characterized in that: The exposed portion of the guide fixing steel plate (3) near the surrounding rock faces away from the tunnel face, while the exposed portion of the guide fixing steel plate (3) near the tunnel interior faces towards the tunnel face.

5. The steel arch frame arch foot fixing device for loess tunnels according to claim 4, characterized in that: The center of the exposed portion of the guide fixing steel plate (3) is provided with guide fixing holes (6), and the locking foot anchor pipe (2) is set in the guide fixing holes (6).

6. The steel arch frame arch foot fixing device for loess tunnels according to claim 5, characterized in that: The diameter of the guide fixing hole (6) is larger than the diameter of the locking foot anchor pipe (2).

7. The steel arch frame arch foot fixing device for loess tunnels according to claim 5, characterized in that: The edges of the guide fixing holes (6) are respectively provided with reinforcing fixing structures.

8. The steel arch frame arch foot fixing device for loess tunnels according to claim 7, characterized in that: The reinforced fixing structure includes multiple short steel bars (5), which are respectively set at the upper and lower edges of the guide fixing hole (6), and one side of the short steel bar (5) is fixed to the guide fixing steel plate (3), and the other side is fixed to the locking foot anchor pipe (2).

9. The steel arch frame arch foot fixing device for loess tunnels according to claim 1, characterized in that: Let the length of the anchor pipe installed perpendicular to the tunnel axis in the original design be L, and the horizontal angle between the anchor pipe (2) and the tunnel vertical be respectively... and The length of the extended anchor pipe (2) is then... , They respectively satisfy: , .

10. A construction method for a steel arch frame arch foot fixing device suitable for loess tunnels according to any one of claims 1-9, characterized in that: The construction method includes the following steps: According to the design requirements, the steel frame (1) is processed. Multiple sets of guide fixing steel plates (3) are set on the two side flange plates (4) of the steel frame (1) in an asymmetrical manner, and the position of the guide fixing holes (6) is ensured to be accurate. After one cycle of tunnel excavation, a steel frame (1) with guide and fixing steel plates (3) is erected, and the core soil (7) is retained. According to the forward-sloping design angle, a down-the-hole drill is used to pass the anchor pipe (2) through the guide fixing hole (6) of the guide fixing steel plate (3) and drill it to the extended design length; Fix the anchor pipe (2) to the guide fixing steel plate (3) and set a short steel bar (5) at the guide fixing hole (6); Repeat the above steps to complete the construction of all anchor pipes (2).

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