A method for supporting irregularly shaped steel arch frames at tunnel intersections

Abstract

This invention provides a method for supporting tunnel intersections with irregularly shaped steel arch frames, relating to the field of tunnel construction technology, and solves the problem of poor support effect at intersections in existing technologies. It includes the following steps: excavating transverse tunnels from both sides of the main tunnel, installing transverse tunnel steel arch frame support while excavating, and installing the last transverse tunnel steel arch frame upon reaching the intersection; widening the intersection to connect the two transverse tunnels and initially shotcreting with concrete support, then installing several irregularly shaped steel arch frames, with both ends of the irregularly shaped steel arch frames connected to the last transverse tunnel steel arch frame; installing anchor bolts and reinforcing mesh on the arch top of the intersection, and then re-shotcreting with concrete until the inner wall of the intersection is flush with the inner wall of the main tunnel; and constructing a secondary lining. The installation of irregularly shaped steel arch frames at the intersection, with the ends of the irregularly shaped steel arch frames connected to the transverse tunnel steel arch frames on both sides, creates a support structure with better support effect in conjunction with the transverse tunnel steel arch frames. Furthermore, the transverse tunnel steel arch frames are normal ground-mounted steel arch frames, which can better support the irregularly shaped steel arch frames.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and more specifically, to a method for supporting irregularly shaped steel arch frames at tunnel intersections. Background Technology

[0002] During tunnel construction, due to the excessive length of the tunnel, cross passages for smoke extraction are required. After connecting with the main tunnel, the cross passages form a cross-shaped tunnel. To increase the construction speed of the main tunnel, the cross passages are usually excavated first, and then excavation proceeds from the intersection towards both directions of the main tunnel. This increases the construction surface area and thus shortens the construction time.

[0003] In existing technologies, the initial support steel frames for the cross passage and the main tunnel at the intersection cannot be grounded and rely entirely on reinforced anchor bolts to support the initial support steel frames. This is a weak area, and in order to ensure the normal construction progress of the tunnel, the secondary lining cannot be constructed in time, posing a significant safety hazard. Another approach is to construct a portal-shaped arch frame on the normal cross section to support the arch top of the intersection. However, because the portal-shaped arch frame is prone to deformation under large compressive forces, the support effect is also poor. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a method for supporting irregularly shaped steel arch frames at tunnel intersections. This method involves installing irregularly shaped steel arch frames at the intersection and connecting the ends of these frames to transverse steel arch frames on both sides. Compared to portal-shaped arch frames, the irregularly shaped steel arch frames, in conjunction with the transverse steel arch frames, form a support structure with better support performance. Furthermore, the transverse steel arch frames are normal ground-mounted steel arch frames, which provide better support for the irregularly shaped steel arch frames.

[0005] The embodiments of the present invention are achieved through the following technical solutions:

[0006] A method for supporting irregularly shaped steel arch frames at tunnel intersections includes the following steps:

[0007] Step S1: Excavate the transverse tunnels from both sides of the main tunnel, and install the transverse tunnel steel arch support while excavating. After reaching the intersection, install the last transverse tunnel steel arch.

[0008] Step S2: Widen the excavation at the intersection to connect the two cross tunnels and initially spray concrete for support. Then install several irregular steel arch frames, with both ends of the irregular steel arch frames connected to the last cross tunnel steel arch frame.

[0009] Step S3: Install anchor bolts and steel mesh on the arch of the intersection, and spray concrete until the inner wall of the intersection is flush with the inner wall of the main tunnel.

[0010] Step S4: Apply the secondary lining.

[0011] Preferably, in step S1, after the transverse tunnel is formed, initial spraying of concrete is performed, followed by the installation of anchor bolts and steel mesh. After the steel arch frame of the transverse tunnel is installed, subsequent spraying of concrete is performed.

[0012] Preferably, the two ends of the irregular steel arch frame are fixed with locking foot anchors, and at least four locking foot anchors are configured at one end.

[0013] Preferably, the length of the anchor bolt is 3m.

[0014] Preferably, the interval between two adjacent irregularly shaped steel arch frames is 60cm.

[0015] Preferably, steel reinforcement supports are welded between two adjacent irregularly shaped steel arch frames.

[0016] Preferably, in step S2, the upper step of the intersection on one side of the centerline of the transverse tunnel is excavated first and the irregular steel arch frame is installed in sequence, then the lower step is excavated downwards, and then the upper and lower steps of the intersection on the other side of the centerline of the transverse tunnel are excavated.

[0017] Preferably, the highest point of the arch at the intersection is at least 50cm higher than the arch of the main opening.

[0018] Preferably, the last horizontal arch steel frame is formed by attaching and welding two steel arch frames together.

[0019] Preferably, the curvature of the irregularly shaped steel arch frames installed from the centerline of the transverse opening to both sides increases sequentially.

[0020] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0021] By installing irregularly shaped steel arches at the intersection and connecting the ends of the irregularly shaped steel arches to the horizontal steel arches on both sides, the irregularly shaped steel arches, in combination with the horizontal steel arches, form a support structure with better support effect compared to the portal-shaped arches. Furthermore, the horizontal steel arches are normal ground-mounted steel arches, which can better support the irregularly shaped steel arches. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a three-dimensional structural schematic diagram provided for an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the installation of the irregular steel arch frame provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the longitudinal cross-sectional structure of the main tunnel provided in an embodiment of the present invention.

[0026] Icons: 1-Main tunnel; 2-Horizontal tunnel; 3-Steel arch frame of horizontal tunnel; 4-Irregular steel arch frame; 5-Anchor bolt. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] The following is combined with Figures 1-3 The present invention will be described in detail below.

[0030] Example

[0031] A method for supporting irregularly shaped steel arch frames at tunnel intersections includes the following steps:

[0032] Step S1: Excavate the transverse tunnels 2 from both sides of the main tunnel 1, and install the transverse tunnel steel arch frame 3 for support while excavating. After reaching the intersection, install the last transverse tunnel steel arch frame 3.

[0033] Step S2: Widen the excavation of the intersection to connect the two cross tunnels 2 and initially spray concrete for support. Then install several irregular steel arch frames 4, with both ends of the irregular steel arch frames 4 connected to the last cross tunnel steel arch frame 3.

[0034] Step S3: Install anchor bolts and steel mesh on the arch of the intersection, and then spray concrete until the inner wall of the intersection is flush with the inner wall of the main opening 1; after the intersection is formed, the cross-section of the intersection is close to an ellipse. This ensures both good stress distribution and aesthetics.

[0035] Step S4: Apply the secondary lining.

[0036] In step S1, after the transverse tunnel 2 is formed, initial sprayed concrete is applied, followed by the installation of anchor bolts and steel mesh. After the transverse tunnel steel arch frame 3 is installed, subsequent sprayed concrete is applied.

[0037] To further increase the stability of the irregular steel arch frame 4, anchor bolts 5 are used to fix both ends of the irregular steel arch frame 4, and at least four anchor bolts 5 are configured at one end. The length of the anchor bolts 5 is 3m.

[0038] The interval between two adjacent irregular steel arch frames 4 is 60cm.

[0039] Steel reinforcement supports are welded between two adjacent irregular steel arch frames 4, connecting all the irregular steel arch frames 4 into a whole, further increasing the support strength of the irregular steel arch frames 4 for the arch top.

[0040] In step S2, the upper step of the intersection on one side of the centerline of the transverse tunnel 2 is excavated and the irregular steel arch frame 4 is installed in sequence. Then the lower step is excavated downwards, and the upper and lower steps of the intersection on the other side of the centerline of the transverse tunnel 2 are excavated.

[0041] The highest point of the arch at the intersection is at least 50cm higher than the arch of the main tunnel.

[0042] The last horizontal tunnel steel arch frame 3 is made by attaching and welding two steel arch frames together; the main tunnel 1 near the intersection is also made by attaching and welding steel arch frames together. That is, all four tunnel openings at the cross intersection are equipped with double-layer steel arch frames to ensure the support strength at the intersection.

[0043] To control the cross-section of the intersection to be close to an ellipse, the curvature of the irregularly shaped steel arch frames 4 installed from the centerline of the transverse opening 2 towards both sides increases sequentially. Furthermore, the irregularly shaped steel arch frames 4 are installed one frame, one step, one curvature at a time to ensure the stability of the intersection's support.

[0044] In step S3, when spraying concrete, attention should be paid to ensuring that the back of the irregular steel arch frame 4 and the surrounding rock are sprayed tightly and closely. If they are not tightly fitted, concrete blocks of the same grade can be used to fill them tightly or grouting can be used to ensure that there are no voids behind the irregular steel arch frame 4 in the initial support, which is conducive to the irregular steel arch frame 4 and the surrounding rock forming a joint support body to share the force.

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for supporting irregularly shaped steel arch frames at tunnel intersections, characterized in that, Includes the following steps: Step S1: Excavate the transverse tunnels from both sides of the main tunnel, and install the transverse tunnel steel arch support while excavating. After reaching the intersection, install the last transverse tunnel steel arch. Step S2: Widen the excavation at the intersection to connect the two cross tunnels and initially spray concrete for support. Then install several irregular steel arch frames, with both ends of the irregular steel arch frames connected to the last cross tunnel steel arch frame. In step S2, the upper step of the intersection on one side of the centerline of the transverse tunnel is excavated and the irregular steel arch frame is installed in sequence. Then the lower step is excavated downwards. Then the upper and lower steps of the intersection on the other side of the centerline of the transverse tunnel are excavated. The curvature of the irregularly shaped steel arches installed from the centerline of the transverse tunnel toward both sides increases sequentially; Step S3: Install anchor bolts and steel mesh on the arch of the intersection, and spray concrete until the inner wall of the intersection is flush with the inner wall of the main tunnel. Step S4: Apply the secondary lining.

2. The method for supporting irregularly shaped steel arch frames at a tunnel intersection according to claim 1, characterized in that, In step S1, after the transverse tunnel is formed, initial sprayed concrete is applied, followed by the installation of anchor bolts and steel mesh. After the steel arch frame of the transverse tunnel is installed, a second spray of concrete is applied.

3. The method for supporting irregularly shaped steel arch frames at a tunnel intersection according to claim 1, characterized in that, The two ends of the irregular steel arch frame are fixed with locking foot anchors, and at least four locking foot anchors are configured at one end.

4. The method for supporting irregularly shaped steel arch frames at a tunnel intersection according to claim 3, characterized in that, The length of the anchor bolt is 3m.

5. The method for supporting irregularly shaped steel arch frames at a tunnel intersection according to claim 1, characterized in that, The interval between two adjacent irregularly shaped steel arch frames is 60 cm.

6. The method for supporting irregularly shaped steel arch frames at a tunnel intersection according to claim 1, characterized in that, Steel reinforcement supports are welded between two adjacent irregularly shaped steel arch frames.

7. The method for supporting irregularly shaped steel arch frames at a tunnel intersection according to claim 1, characterized in that, The highest point of the arch at the intersection is at least 50cm higher than the arch of the main tunnel.

8. The method for supporting irregularly shaped steel arch frames at a tunnel intersection according to claim 1, characterized in that, The last horizontal arch frame was formed by attaching and welding two steel arch frames together.

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