Tunnel collapse treatment structure

Abstract

The application relates to a tunnel collapse treatment structure. The application is suitable for the technical field of hydropower station tunnels. The technical problem to be solved by the application is to provide a tunnel collapse treatment structure. The technical scheme adopted by the application is as follows: a tunnel collapse treatment structure comprises a tunnel top supporting structure arranged above a tunnel collapse cavity and used for supporting the upper cavity of the tunnel collapse section; a drainage structure arranged in the inside of the tunnel top supporting structure and used for draining the seepage water in the inside of the tunnel top supporting structure; a steel arch structure arranged in the inside of the tunnel collapse cavity, the steel arch structure being arranged below the tunnel top supporting structure and used for providing construction protection; and a concrete backfilling structure arranged on the circumferential side of the steel arch structure and capable of reinforcing the upper vault, the two side haunches and the bottom spring of the tunnel collapse section.

Description

Technical Field

[0001] This utility model relates to the field of hydropower station tunnel technology, and in particular to a structure for handling tunnel collapse. Background Technology

[0002] Water conservancy and hydropower projects, underground space engineering projects, and other engineering projects all contain cavern structures such as water diversion tunnels, access tunnels, and construction adits. For long-distance water diversion power stations, the water diversion tunnels are long and need to pass through various complex geological structures, and the surrounding rock conditions are also unstable. In addition, these types of tunnels are difficult to maintain and have long maintenance cycles. Many problems that may occur during operation are not easy to occur, ultimately leading to collapses within the tunnel.

[0003] Because the tunnel collapse exposed the original surrounding rock and created a huge cavity above the arch, the collapsed material would accumulate downstream, and the stability of the collapsed area was poor, requiring timely treatment of the collapse site inside the tunnel. However, considering that traditional construction methods could not guarantee the safety of construction workers under these circumstances, there were not only serious safety hazards, but the treatment effect could not achieve the expected results, and the time and cost were also long.

[0004] Therefore, there is an urgent need for a tunnel collapse treatment structure that can improve treatment effectiveness, ensure construction safety, and increase construction efficiency. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a structure for handling tunnel collapses, in view of the above-mentioned problems.

[0006] The technical solution adopted by this utility model is: a tunnel collapse treatment structure, comprising:

[0007] The tunnel roof support structure is located above the collapsed cavity of the tunnel and is used to provide support for the cavity above the collapsed section of the tunnel.

[0008] Drainage structure, located inside the tunnel roof support structure, is used to guide and drain seepage water from inside the tunnel roof support structure.

[0009] The steel arch frame structure is located inside the tunnel cavity and below the tunnel roof support structure to provide construction protection.

[0010] The concrete backfill structure, located around the steel arch frame structure, can reinforce the upper arch crown, the two sides of the arch waist, and the bottom arch foot of the collapsed section of the tunnel.

[0011] Through the aforementioned technical means, the steel arch frame structure provides a safe working environment for construction workers, enhances the temporary stability of the tunnel collapse section, and utilizes the tunnel roof support structure to support the top cavity of the tunnel collapse section, sharing part of the load on the cavity. The drainage structure inside the tunnel roof support structure can reduce the impact of water pressure on the structure by guiding and draining seepage water, which helps maintain the stability of the surrounding rock. The concrete backfill structure around the steel arch frame structure improves the overall strength and durability of the structure and also improves the load distribution.

[0012] In some embodiments, the steel arch structure includes a portal steel arch, which is formed by welding I-beam arches. A protective layer is formed by welding steel plates to the outer side of the I-beam arches. The I-beam arches are reinforced by welding with threaded steel or angle steel. Multiple portal steel arches are arranged at intervals in the tunnel collapse section. The outermost portal steel arches at both ends are fixed to the tunnel bedrock by anchor bolts. The portal steel arches in the middle position are welded and fixed to the outer portal steel arches by transverse anchor bars.

[0013] In some embodiments, the tunnel roof support structure includes anchor bolts and strip concrete layers. Multiple anchor bolts are at least partially drilled into the top of the tunnel collapse cavity. A strip concrete layer located at the top of the steel arch frame structure is provided above the tunnel collapse cavity. The drainage structure is provided inside the strip concrete layer. A partial cavity is left at the top of the strip concrete layer. The strip concrete layer can bear the load of the cavity above.

[0014] In some embodiments, the drainage structure includes drainage holes, and the interior of the strip-shaped concrete layer is provided with drainage holes arranged along the tunnel extension direction, with multiple drainage holes arranged at intervals.

[0015] In some embodiments, the diameter of the drainage hole is 50mm to 100mm, the slope of the drainage hole is 5%, and the arrangement spacing of the drainage holes is 2m.

[0016] In some embodiments, the top surface of the strip-shaped concrete layer is provided with a geotextile-wrapped filter layer.

[0017] In some embodiments, the top collapse section within the tunnel collapse segment is sealed with shotcrete, and the surrounding collapse body is reinforced with grout.

[0018] In some embodiments, the concrete backfill structure includes a top arch backfill layer, a side wall backfill layer, and a bottom backfill layer. Concrete is backfilled at the arch top, the two sides of the arch waist, and the arch bottom of the steel arch frame structure to form the top arch backfill layer, the side wall backfill layer, and the bottom backfill layer respectively.

[0019] In some embodiments, a double-layer concrete lining of fine stone is provided between the arch waist of the steel arch frame structure and the backfill layer of the side wall.

[0020] Another technical solution adopted by this utility model is: a construction method for a tunnel collapse treatment structure, comprising the following steps:

[0021] S1. The steel arch frame structure is constructed by welding I-beams to form a portal steel arch frame on the outer wall of the tunnel. Steel plates are welded on the outside to form a protective layer. The outermost portal steel arch frame is close to the bedrock and fixed with locking anchor rods. The middle portal steel arch frame is connected to the outer portal steel arch frame by transverse anchor bars.

[0022] S2. Surrounding rock reinforcement treatment: spray concrete at the top of the collapsed section of the tunnel to seal the exposed surrounding rock, and grouting to reinforce the surrounding loose surrounding rock.

[0023] S3. Template installation: Mark lines and lay out according to the construction drawings, install templates on site, ensure tight splicing of templates to prevent misalignment, and set up temporary supports during template installation to prevent deformation.

[0024] S4. Concrete pouring: First, pour concrete for the tunnel sidewalls, then pour concrete for the left and right arch waists, arch feet and arch tops of the steel arch frame structure in sections. After pouring, vibrate and compact immediately. After the bottom plate surface is repaired, spray water for curing to prevent cracks.

[0025] S5. Drainage structure construction: A sand and gravel filter layer is laid on top of the strip concrete layer located above the portal steel arch frame, wrapped with geotextile and pre-embedded with drainage holes.

[0026] S6. Stress monitoring: Real-time monitoring of stress on the tunnel roof and sidewalls during construction.

[0027] The beneficial effects of this utility model are:

[0028] 1. Construction protection is provided through a steel arch frame structure, and the tunnel roof support structure supports the cavity at the top of the tunnel, with the reserved cavity reducing the load. The drainage structure within the tunnel roof support structure can promptly drain internal seepage, reducing the impact of water pressure on the structure and mitigating the risk of secondary collapse caused by seepage from heavy rain or other unforeseen circumstances. Simultaneously, a four-compartment concrete backfill structure is formed around the steel arch frame structure from bottom to top, reinforcing key areas, improving the overall strength and durability of the structure, and also improving load distribution. This application utilizes common equipment and building materials available at the construction site to quickly and effectively repair collapsed areas to maintain tunnel stability, making construction convenient and cost-effective. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the cross-sectional structure of this application.

[0030] Figure 2This is a cross-sectional schematic diagram of the steel arch frame structure in this application.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Fine aggregate double-layer concrete lining; 3. Drainage holes; 4. Steel arch frame structure; 5. Anchor bolts; 201. Side wall backfill layer; 202. Top arch backfill layer; 203. Strip concrete layer; 204. Bottom backfill layer.

[0033] This specification includes references to "one embodiment" or "implementation". The use of the phrase "in one embodiment" or "in an embodiment" does not necessarily refer to the same embodiment. Specific features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure.

[0034] The term "comprising" is open-ended. As used in the appended claims, it does not exclude additional structures or steps.

[0035] "First," "second," etc. As used in this article, these terms serve as labels for the nouns preceding them and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.). Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below with reference to specific embodiments.

[0037] Example 1:

[0038] Combination Figures 1 to 2 As shown, this embodiment is a tunnel collapse treatment structure, including a tunnel top support structure, a drainage structure, a steel arch frame structure 4, and a concrete backfill structure. The steel arch frame structure 4 is located inside the collapsed tunnel cavity, and the tunnel top support structure is located above the steel arch frame structure 4. The steel arch frame structure 4 provides construction protection. A partial cavity is left between the tunnel top support structure and the inner wall of the collapsed section's top; the tunnel top support structure provides support for this cavity. A drainage structure is located inside the tunnel top support structure to drain seepage water. A concrete backfill structure is located around the steel arch frame structure 4, which reinforces the upper arch, the side arch waists, and the bottom arch feet of the collapsed tunnel section.

[0039] In some implementation schemes, the collapsed section above the accumulated material within the tunnel collapse zone is sealed with shotcrete, and the surrounding collapsed body is reinforced with grout. Specifically, in this embodiment, the loose surrounding rock is reinforced with grout using a water-cement ratio of 0.8:1.

[0040] By using shotcrete to seal the exposed surrounding rock surface, the loose rock can be quickly stabilized, preventing further rockfall. Simultaneously, grouting reinforcement of the surrounding collapsed area effectively fills cracks and pores, improving the integrity and strength of the surrounding rock, enhancing its self-stabilizing capacity, and preventing secondary collapses caused by surrounding rock instability.

[0041] In some implementation schemes, the tunnel roof support structure includes anchor bolts 5 and strip-shaped concrete layers 203. Multiple anchor bolts 5 are at least partially drilled into the top of the tunnel collapse cavity. A strip-shaped concrete layer 203, located atop the steel arch structure 4, is situated above the tunnel collapse cavity. The strip-shaped concrete layer 203 has a drainage structure inside, and a partial cavity is left at the top. The strip-shaped concrete layer 203 can bear the load of the cavity above. Combined with the anchor bolts 5 at the top, this makes the overall structure more stable and robust, reducing the risk of secondary collapse. Specifically, in this embodiment, the strip-shaped concrete layer 203 uses C25 concrete with a thickness of not less than 1.5m.

[0042] Furthermore, the drainage structure includes drainage holes 3. Drainage holes 3 are arranged along the tunnel extension direction inside the strip-shaped concrete layer 203, with multiple drainage holes 3 spaced apart. Specifically, in this embodiment, the drainage holes 3 are formed by pre-embedding φ80 PVC drainage pipes within the strip-shaped concrete layer 203.

[0043] Furthermore, the diameter of the drainage hole 3 is 50mm to 100mm, the slope of the drainage hole 3 is 5%, and the spacing between the drainage holes 3 is 2m.

[0044] Furthermore, a geotextile-wrapped filter layer is provided on the top surface of the strip concrete layer 203. Specifically, in this embodiment, a 30cm thick graded sand and gravel filter layer is laid on top of the strip concrete layer 203.

[0045] By arranging a filter layer on top of the strip concrete layer 203, fine particles are prevented from entering the drainage hole 3, thus preventing the drainage hole 3 from being blocked and ensuring the long-term effectiveness of the drainage structure.

[0046] Furthermore, rain shelters can be installed at the top of the landslide area.

[0047] By drilling multiple anchor bolts 5 into the top of the tunnel cavity, direct support was provided to the unstable surrounding rock, preventing further collapse. The strip-shaped concrete layer 203 improved the stress distribution at the top, reducing localized stress concentration. A partial cavity was left at the top of the strip-shaped concrete layer 203, with drainage holes 3 inside, which helps to drain seepage water, reduce the impact of water pressure on the structure, and maintain the integrity and stability of the structure.

[0048] In some implementation schemes, the steel arch structure 4 includes portal steel arches, which are formed by welding I16 type I-beam arches. A 4mm steel plate is welded to the outer side of each I-beam arch to form a protective layer. The I-beam arches are reinforced by welding with threaded steel or angle steel. Multiple portal steel arches are arranged at intervals within the tunnel collapse section. Specifically, in this embodiment, eight portal steel arches are arranged within the tunnel collapse section. The outermost portal steel arches at both ends are close to the bedrock and fixed to the tunnel bedrock interior by anchor bolts. The two portal steel arches in the middle positions are welded and fixed to the two outer portal steel arches by transverse anchor bars.

[0049] The use of portal steel arches enhanced the temporary support capacity of the construction area, ensuring the safety of construction workers.

[0050] In some implementations, the concrete backfill structure includes a top arch backfill layer 202, a side wall backfill layer 201, and a bottom backfill layer 204. Concrete is backfilled at the top of the steel arch frame structure 4, at the waists of the two sides of the arch, and at the bottom of the arch to form the top arch backfill layer 202, the side wall backfill layer 201, and the bottom backfill layer 204 respectively.

[0051] Furthermore, a fine stone double-layer concrete lining 1 is provided between the arch waist of the steel arch frame structure 4 and the backfill layer 201 of the side wall, and the fine stone double-layer concrete lining 1 extends outward by 1m to both sides of the tunnel.

[0052] By setting a fine stone double-layer concrete lining 1 between the arch waist of the steel arch frame structure 4 and the backfill layer 201 of the side wall, the shear resistance and integrity of the steel arch frame structure 4 can be enhanced, and structural deformation or damage caused by lateral pressure can be prevented.

[0053] Furthermore, in this embodiment, the top arch backfill layer 202 is made of C30 concrete, and is poured symmetrically to prevent eccentric pressure. The side wall backfill layer 201 is made of C25 fine aggregate concrete, with a total thickness of 1.2m for the double-layer lining. The bottom backfill layer 204 is made of C20 concrete, with a thickness of 0.8m.

[0054] Furthermore, the free fall height of concrete when it is poured into the formwork should not exceed 1.5m.

[0055] The implementation principle of a tunnel collapse treatment structure is as follows:

[0056] The steel arch structure 4 provides a safe working environment for construction workers, preventing injuries from falling debris and enhancing the temporary stability of the entire area, which is especially important in case of emergencies during the process. The top anchor bolts 5, in conjunction with the strip concrete layer 203, provide support to the tunnel's top cavity, preventing further collapse. The filter layer on the top surface of the strip concrete layer 203, along with the internal drainage holes 3, effectively drains internal seepage water, reducing the impact of water pressure on the structure, helping to maintain the stability of the surrounding rock and lowering the risk of secondary collapse caused by water. The combined action of the strip concrete layer 203 and the steel arch structure 4 disperses pressure from above, reducing the risk of instability caused by stress concentration. Reinforcing key components such as the arch crown, arch waist, and arch feet with concrete backfill significantly improves the structure's load-bearing capacity and deformation resistance, effectively preventing secondary collapse.

[0057] Example 2:

[0058] This embodiment describes a construction method for a tunnel collapse treatment structure, applied to the tunnel collapse treatment structure in Embodiment 1, and includes the following steps:

[0059] S1. The steel arch frame structure 4 is constructed by welding I-beams to form a portal steel arch frame on the outer wall of the tunnel. Steel plates are welded on the outside to form a protective layer. The outermost portal steel arch frame is close to the bedrock and fixed with locking anchor rods. The middle portal steel arch frame is connected to the outer portal steel arch frame by transverse anchor bars.

[0060] S1.1. I16 I-beams are welded to form a portal steel arch frame. A 4mm steel plate is welded to the outside of the I-beam arch frame to form a protective layer. The I-beam arch frames are reinforced by transverse welding with threaded steel or angle steel.

[0061] S2. Surrounding rock reinforcement treatment: Shot concrete is sprayed at the top of the collapsed section of the tunnel to seal the exposed surrounding rock, and grouting is used to reinforce the surrounding loose surrounding rock.

[0062] S3. Template installation: Mark lines and lay out the templates according to the construction drawings, install the templates on site, ensure tight splicing of the templates to prevent misalignment, and set up temporary supports during the template installation process to prevent deformation.

[0063] S3.1 Layout and setting out: Measure and set out according to the construction drawings.

[0064] S3.2. When installing and splicing the formwork on site, attention should be paid to the quality of splicing, ensuring that the joints are flat and tight to prevent misalignment. Sufficient temporary support facilities should be set up during the formwork installation process to prevent deformation and overturning.

[0065] S3.3 Specific template layout: No template is erected on the base plate. Wooden templates are used for the side walls and ends. The top arch is made of Φ28 steel bars welded into a fixed arc support. The supports are then arranged in an orderly manner on the load-bearing frame with a spacing of 50cm. Steel pipes are used to lock the arc support above and below. Finally, 8cm×10cm square timber is laid on the fixed arc support with a spacing of 15cm. The template is then fixed on the square timber.

[0066] S4. Concrete pouring: First, concrete is poured for the tunnel sidewalls, and then concrete is poured in sections for the left and right arch waists, arch feet and arch tops of the steel arch frame structure 4. After pouring, the concrete is immediately vibrated to make it dense. After the bottom plate surface is repaired, it is sprayed with water for curing to prevent cracks.

[0067] S4.1 First, ensure the formwork is securely installed, and pouring should be symmetrical from left to right. After the sidewall concrete is poured, move the concrete delivery pipe to the left and right arch waists, arch feet, and arch crowns for pouring. The concrete delivery direction for the arch and sidewalls should be from downhill to uphill. The free fall height of the concrete when poured into the formwork should not exceed 1.5m to prevent segregation.

[0068] S4.2 Concrete configuration for each part:

[0069] The concrete sidewalls are backfilled with C25 fine aggregate concrete, and the total thickness of the double-layer lining is 1.2m.

[0070] The concrete arch backfill is made of C30 concrete, and it is poured symmetrically to prevent eccentric pressure.

[0071] The strip-shaped concrete layer 203 is backfilled with C25 concrete, with a thickness of 1.5m;

[0072] The bottom of the concrete was backfilled with C20 concrete, with a thickness of 0.8m.

[0073] 4.3 After the concrete slab is poured, leveled, and vibrated, the concrete surface should be repaired and compacted. After compaction, the surface should be sprayed and watered to prevent the formation of surface cracks.

[0074] S5. Drainage structure construction: A sand and gravel filter layer is laid on top of the strip concrete layer 203 located above the portal steel arch frame, wrapped with geotextile and pre-embedded with drainage holes 3.

[0075] S5.1, Φ80 PVC drainage pipes are pre-embedded inside the strip concrete layer 203. The diameter of the drainage holes 3 is Φ50~100mm, the longitudinal spacing is 2m, and the slope is 5%. Rain shelters can also be set up in the top area of ​​the collapse.

[0076] S5.2, A 30cm thick graded sand and gravel filter layer is laid on top of the strip concrete layer 203, and then wrapped with geotextile.

[0077] S6. Stress monitoring: Real-time monitoring of stress on the tunnel roof and sidewalls during construction.

[0078] S6.1. Throughout the entire construction process, real-time stress monitoring will be conducted on the top and sidewalls of the tunnel to ensure that the structural stress is within a reasonable range during construction and to prevent safety accidents caused by abnormal stress.

[0079] The above are all preferred embodiments of this utility model, and are not intended to limit the scope of protection of this utility model. Therefore, all equivalent changes made to the structure, shape and principle of this utility model should be covered within the scope of protection of this utility model.

Claims

1. A structure for handling tunnel collapses, characterized in that, include: The tunnel roof support structure is located above the collapsed cavity of the tunnel and is used to provide support for the cavity above the collapsed section of the tunnel. Drainage structure, located inside the tunnel roof support structure, is used to guide and drain seepage water from inside the tunnel roof support structure. The steel arch frame structure (4) is located inside the tunnel collapse cavity. The steel arch frame structure (4) is located below the tunnel roof support structure and is used to provide construction protection. The concrete backfill structure is located on the periphery of the steel arch frame structure (4) and can reinforce the upper arch, the two sides of the arch waist and the bottom arch foot of the tunnel collapse section. The steel arch frame structure (4) includes a portal steel arch frame. The portal steel arch frame is formed by welding I-beam arch frames. The outer side of the I-beam arch frame is welded with steel plates to form a protective layer. The I-beam arch frames are reinforced by welding with threaded steel or angle steel. Multiple portal steel arch frames are arranged at intervals in the tunnel collapse section. The portal steel arch frames at both ends are fixed to the tunnel bedrock by locking foot anchor rods. The portal steel arch frames in the middle position are welded and fixed to the portal steel arch frames in the outer position by transverse anchor bars. The tunnel roof support structure includes anchor rods (5) and strip concrete layers (203). Multiple anchor rods (5) are at least partially drilled in the upper part of the tunnel collapse cavity. A strip concrete layer (203) located at the top of the steel arch frame structure (4) is provided in the upper part of the tunnel collapse cavity. The drainage structure is provided inside the strip concrete layer (203). A partial cavity is left at the top of the strip concrete layer (203). The strip concrete layer (203) can bear the load of the upper cavity. The drainage structure includes drainage holes (3), and the interior of the strip concrete layer (203) is provided with drainage holes (3) arranged along the tunnel extension direction, and multiple drainage holes (3) are arranged at intervals. The concrete backfill structure includes a top arch backfill layer (202), a side wall backfill layer (201), and a bottom backfill layer (204). The top of the steel arch frame structure (4), the waists of the two sides of the arch, and the bottom of the arch are backfilled with concrete to form the top arch backfill layer (202), the side wall backfill layer (201), and the bottom backfill layer (204).

2. The tunnel collapse handling structure according to claim 1, characterized in that: The diameter of the drainage hole (3) is 50mm~100mm, the slope of the drainage hole (3) is 5%, and the arrangement spacing of the drainage hole (3) is 2m.

3. The tunnel collapse handling structure according to claim 1, characterized in that: The top surface of the strip concrete layer (203) is provided with a geotextile-wrapped filter layer.

4. The tunnel collapse handling structure according to claim 1, characterized in that: The steel arch frame structure (4) has a double-layer concrete lining (1) between the arch waist and the side wall backfill layer (201).

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