A method for partial lining construction to treat severe defects in the lower anchor section of a railway tunnel

Abstract

This invention discloses a partial lining construction method for treating severe defects in the lower anchor section of a railway tunnel. Grouting anchors are evenly installed within the treatment area. Concrete at the enlarged circumferential section of the lower anchor section is removed and extended circumferentially towards the general anchor section section to form a 25cm step. A longitudinal grating steel frame is installed on the step at the junction of the lower anchor section section and the general lining section. The grating steel frame is connected to the grouting anchors, ensuring close contact between the grating steel frame and the original tunnel lining surface. After the formwork is erected, an expansion layer is poured to form a 25cm thick partial lining. After the initial setting of the cast-in-place structure, the gaps behind the lining are filled and compacted using a pre-reserved grouting system. This invention fully utilizes the structural feature of the lower anchor section, which has a larger cross-section than the general lining, minimizing the impact on existing equipment at the lower anchor section, eliminating the need to relocate the contact network compensation device, and effectively eliminating the impact of severe defects in the lower anchor section arch on tunnel operation. The treatment process is safe and reliable.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a method for partial lining construction to treat severe defects in the lower anchor section of a railway tunnel. Background Technology

[0002] The description of the background technology in this invention pertains to related technologies and is used merely for illustration and to facilitate understanding of the invention. It should not be construed as the applicant explicitly believing or presuming that the technology was prior art on the filing date of the first application.

[0003] With the rapid development of road construction, the construction of high-speed railway tunnel foundations is playing an increasingly important role in railway construction projects. Due to the unique structure and location of tunnel walls and foundations, quality control during construction is quite challenging, leading to significant safety risks.

[0004] According to the "Standard for Acceptance of Construction Quality of High-Speed ​​Railway Tunnel Engineering" (TB10753-2018), the secondary lining concrete pouring quality requirements for railway tunnel arch walls must not exhibit phenomena such as voids in the arch crown, insufficient thickness, delamination, cracking, spalling, water leakage, or non-dense concrete. Ensuring that the construction quality of the secondary lining concrete pouring for tunnel arch walls meets the acceptance standards is a technical challenge that needs to be addressed during the construction of high-speed railway tunnels.

[0005] When the concrete was poured to the top of the tunnel, pipe blockage occurred. On-site construction workers, believing it to be full, stopped pumping concrete, resulting in voids. Prematurely removing pipes before the secondary lining concrete had initially set caused the unstabilized concrete to form funnels under its own weight, also leading to voids. When a curved section becomes a straight section, at the change in lining end face, the transition section of the smaller cross-section lining overlaps the larger cross-section lining, leaving a gap. During concrete pouring, this gap is not tightly sealed, causing hollow sounds. Concrete shrinkage and creep also contribute to porosity. Most voids are caused by incomplete or improper filling of the lining concrete during pouring, combined with the concrete's own shrinkage. A minority of cases are due to groundwater, which erodes loose material or fractured surrounding rock at the bottom of the invert arch.

[0006] However, the conventional tunnel foundation construction methods currently used in the industry offer limited solutions to this technical challenge. Existing construction methods are cumbersome and cannot be implemented quickly and easily. Summary of the Invention

[0007] The purpose of this invention is to provide a partial lining construction method for treating severe defects in the lower anchor section of railway tunnels, so as to solve the problem of voids in the secondary lining of existing tunnels.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0009] A method for partial lining construction to treat severe defects in the lower anchor section of a railway tunnel includes the following steps:

[0010] S1. Inspect the tunnel lining and determine the void area based on the inspection results. Set up a working platform below the void area and configure the equipment.

[0011] S2. Install grouting anchors in the treatment area of ​​the lower anchor section and the general anchor section of the tunnel, remove the concrete at the circumferential expansion of the lower anchor section, extend circumferentially to the general anchor section and form a 25cm step, reserve the grouting system, and then clean the step.

[0012] S3. In the treatment area of ​​the tunnel lower anchor section that avoids the contact wire equipment, a longitudinal grid steel frame is erected and the grid steel frame is connected to the grouting anchor rod. Circumferential reinforcement is arranged to connect the grid steel frame in a circumferential direction and to make the grid steel frame closely fit the original tunnel lower anchor section lining surface.

[0013] S4. After erecting the formwork, pour the expansion layer and form a local lining. Ensure that the surface of the local lining is smoothly connected to the unwidened side of the lower anchor section. Insert braces in areas where the thickness is insufficient and where the local lining is not in use.

[0014] S5. After the expansion layer has initially set, backfill and grout through the reserved grouting system until it is compacted, and then treat the surface of the lining after pouring.

[0015] This invention, by following the steps outlined above, effectively avoids voids when the concrete is poured to the top of the tunnel. Furthermore, by filling the secondary lining with an expansion layer and then backfilling with grout through a pre-installed grouting system after the expansion layer has initially set, voids can be prevented. This effectively avoids incomplete or improper filling during the lining concrete pouring process, which could lead to voids.

[0016] Furthermore, the treatment of the lining surface after casting in step S5 includes: cleaning the burrs at the joints of the lining after demolding, and spraying epoxy resin on the local lining and within a range of 40cm to 60cm extending outward from the local lining.

[0017] Furthermore, in step S2, the grouting anchors are evenly distributed in the reinforcement area of ​​the lower anchor section, and the grouting anchors are arranged in a quincunx pattern.

[0018] Furthermore, in step S3, the grid steel frame is erected in the widened area of ​​the lower anchor section, and the distance between the grid steel frame and the contact wire equipment is greater than 25cm.

[0019] Furthermore, the widening range of the lower anchor section is greater than 25cm.

[0020] Further, in step S2: the concrete at the circumferential section of the lower anchor section is removed, and the removal extends 50cm circumferentially to the section of the general anchor section. The removal depth matches the thickness of the repaired lining, and the lining thickness is greater than 25cm.

[0021] Furthermore, the expansion layer in step S4 is made of micro-expansion self-compacting concrete or micro-expansion grouting binder.

[0022] By using micro-expansion self-compacting concrete or micro-expansion grouting binder to ensure the thickness at the arch, and then grouting through an injection system to fill the gaps between the expansion layers, the problems of voids and hollow sounds can be effectively solved.

[0023] Furthermore, in step S4: drill bits are inserted in the area where the lining thickness is less than the original tunnel lining thickness, and the drill bits are arranged in a grid pattern.

[0024] Furthermore, in step S3, circumferential ribs with a longitudinal spacing of 1m are set on the grid steel frame, and a grouting system is reserved.

[0025] Furthermore, in step S2, high-pressure air is used to clean the dust inside the steps. Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention forms a partial lining, then uses a grid steel frame, and sets circumferential reinforcement along the partial lining. After the formwork is erected, an expansion layer is used for grouting to ensure that the thickness at the arch is matched with the original tunnel arch thickness. After the expansion layer has initially set, it is backfilled and grouted through a reserved grouting system until it is compacted, thus effectively avoiding the phenomenon of voids.

[0027] 2. This invention utilizes the existing tunnel lining structure and achieves dense grouting by partially lining, setting grouting anchors, grid steel frames, inserting drill bits, and injecting an expansion layer, and then grouting again after the expansion layer has initially set.

[0028] 3. This invention cleans and grinds the burrs at the lining joints after demolding, and sprays epoxy resin on the local lining and within a range of 40cm to 60cm extending outward from the local lining. This ensures that no cracks will occur at the junction of the newly poured concrete and the original lining, and that no slag will fall off the concrete surface, thus forming an integral load-bearing structure.

[0029] 4. This invention fully utilizes the structural feature of the lower anchor section being larger than that of a general lining section, minimizing the impact on existing equipment at the lower anchor section, eliminating the need to relocate the contact network compensation device, and effectively eliminating the impact of severe defects in the lower anchor section arch on tunnel operation. The treatment process is safe and reliable. Attached Figure Description

[0030] Figure 1A schematic diagram of the cross-section for the large-scale void repair work in the lower anchor section of the tunnel;

[0031] Figure 2 A schematic diagram of a localized reinforcement section;

[0032] Figure 3 This is a schematic diagram of the cross-section of the grating steel frame;

[0033] Figure 4 This is a schematic diagram of the grating steel frame structure;

[0034] Figure 5 This is a schematic diagram of the specific structure of the grating steel frame.

[0035] In the diagram: 1-lower anchor section, 2-grouting anchor rod, 3-contact wire equipment, 4-grid steel frame, 41-parallel steel pipe, 42-connecting steel pipe, 43-fixed steel pipe, 5-general anchor section, 6-partial lining, 7-drill nail. Detailed Implementation

[0036] The technical solution 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figures 1 to 5 As shown, this invention provides a method for partial lining construction to treat severe defects in the lower anchor section of a railway tunnel, comprising the following steps:

[0038] S1. Inspect the tunnel lining and determine the void area based on the inspection results. Set up a working platform below the void area and configure the equipment.

[0039] The work platform can be a railcar with an attached platform or a simple combined work platform; before construction, the construction schedule, the connection of each construction process, and the configuration of equipment should be arranged to ensure construction and operation safety.

[0040] S2. Install grouting anchor rods 2 in the treatment area of ​​the lower anchor section 1 and the general anchor section 5 of the tunnel, remove the concrete at the circumferential section of the lower anchor section 1, extend it circumferentially to the section of the general anchor section 5 and form a 25cm step, reserve the grouting system, and then clean the step.

[0041] The grouting anchor 2 is 3m long and hollow inside. The grouting anchor 2 is evenly distributed in the reinforcement area of ​​the lower anchor section 1. Specifically, grouting anchor 2 with a longitudinal length of 1m and a circumferential length of 0.8m is installed in the reinforcement area of ​​the lower anchor section 1, and the grouting anchor 2 is arranged in a quincunx pattern. Three rows of grouting anchor 2 with a circumferential spacing of 1m are installed in the range of 50cm outside the horizontal projection of the sidewall of the ditch from the edge of the reinforcement area of ​​the lower anchor section of the tunnel.

[0042] The concrete at the circumferential section of the lower anchor section 1 is removed, and the concrete widened by less than 25cm at the circumferential section of the lower anchor section 1 is removed, extending 50cm circumferentially towards the section of the general anchor section 5. The removal depth matches the thickness of the repaired lining, and the lining thickness is greater than 25cm. If the thickness of the lining after removal is less than 15cm, it is also removed to form a regularly shaped local lining 6. At the same time, high-pressure air is used to clean the dust inside the steps.

[0043] S3. In the treatment area of ​​the tunnel lower anchor section 1 that avoids the contact wire equipment 3, a longitudinal grid steel frame 4 is erected and the grid steel frame 4 is connected to the grouting anchor rod 2. Circumferential reinforcement is arranged to connect the grid steel frame 4 in a circumferential direction and the grid steel frame 4 is made to fit closely with the original tunnel lower anchor section lining surface.

[0044] The widening range of the widened area of ​​the lower anchor section 1 is greater than 25cm; the grid steel frame 4 is erected within the widened area of ​​the lower anchor section 1 within the range greater than 25cm, and the distance between the grid steel frame 4 and the contact wire equipment 3 is greater than 25cm. Both ends of the grid steel frame 4 are anchored to the steps at the junction of the lower anchor section 1 and the general anchor section 5. The main reinforcement bars at both ends of the grid steel frame 4 are inserted into the general anchor sections 5 at both ends, and are inserted 25cm into the lining. The grid steel frame 4 uses a 3.5m long steel frame. The grid steel frame 4 is welded and fixed to the grouting anchor rod 2, and the grid steel frame 4 is in close contact with the original tunnel lining surface. Circumferential reinforcement bars are arranged to connect the grid steel frame 4 in a circumferential manner, with the circumferential reinforcement bars arranged longitudinally at 1m intervals. The grid steel frame 4 is in close contact with the original tunnel lining surface of the lower anchor section 1, and a grouting system is reserved.

[0045] The grating steel frame 4 includes two parallel steel pipes 41 and two connecting steel pipes 42 staggered between the two parallel steel pipes 41. The two connecting steel pipes 42 are welded to the parallel steel pipes 41 by fixing steel pipes 43, and the outer walls of both ends of the connecting steel pipes 42 are welded to the outer walls of the parallel steel pipes 41.

[0046] S4. After erecting the formwork, pour the expansion layer and form a local sleeve 6. Ensure that the surface of the local sleeve 6 is smoothly connected to the unwidened side of the lower anchor section 1 in the circumferential direction. Insert the bracing 7 in the area outside the local sleeve 6 and in areas where the thickness is insufficient.

[0047] In areas where the lining thickness is less than that of the original tunnel lining, drill bits 7 are inserted. The drill bits 7 are spaced 40cm apart in the longitudinal and circumferential directions and are arranged in a grid pattern. The outer end of the drill bit 7 is in close contact with the waterproof membrane, and its inner end extends into the cast-in-place concrete.

[0048] S5. After the expansion layer has initially set, backfill and grout through the reserved grouting system until it is compacted, and then treat the surface of the lining after pouring.

[0049] The treatment of the lining surface after pouring includes: grinding the lining surface after demolding, and spraying epoxy resin on the local lining 6 and within a range extending 40cm to 60cm outward from the local lining 6. This ensures that the concrete surface does not crumble, forming a unified load-bearing structure. High-penetration, durable epoxy resin is used.

[0050] The expansion layer uses micro-expansion self-compacting concrete or micro-expansion grouting binder, with a strength grade of C40 and a permeability grade of P8. The expansion layer ensures that the thickness at the arch crown matches the original tunnel lining thickness. The repair structure is more than 10cm away from the contact wire equipment 3, ensuring that the new reinforcement structure is effectively connected to the original lining structure as a whole. After the initial setting of the cast-in-place concrete, backfill grouting is carried out through a pre-reserved grouting system to fill the gaps densely.

[0051] This invention follows the construction steps of installing grouting anchor bolts 2, removing concrete from the circumferentially enlarged section of the lower anchor section 1, erecting a longitudinal grid steel frame 4, setting up formwork, pouring an expansion layer, and grouting until compacted. Grouting anchor bolts 2 are evenly installed within the treatment area. The concrete from the circumferentially enlarged section of the lower anchor section 1 is removed and extended circumferentially towards the general anchor section 5 to form a 25cm step. A longitudinal grid steel frame 5 is installed on the step at the junction of the lower anchor section 1 and the general lining section of the railway tunnel. The grid steel frame 5 is connected to the grouting anchor bolts 2, ensuring close contact between the grid steel frame 4 and the original tunnel lining surface. After setting up the formwork, an expansion layer is poured to form a 25cm thick local lining. After the initial setting of the cast-in-place structure, the gaps behind the lining are filled and compacted using a pre-reserved grouting system. This invention fully utilizes the structural feature of the lower anchor section having a larger cross-section than the general lining, minimizing the impact on existing equipment at the lower anchor section, eliminating the need to relocate the contact network compensation device, and effectively eliminating the impact of severe defects in the arch of the lower anchor section 1 on tunnel operation.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for partial lining construction to treat severe defects in the lower anchor section of a railway tunnel, characterized in that, Includes the following steps: S1. Inspect the tunnel lining and determine the void area based on the inspection results. Set up a working platform below the void area and configure the equipment. S2. Grouting anchors (2) are installed in the treatment area of ​​the lower anchor section (1) and the general anchor section (5) of the tunnel. The concrete at the circumferential section of the lower anchor section (1) is removed and extended circumferentially to the section of the general anchor section (5) to form a 25cm step. A grouting system is reserved, and then the step is cleaned. S3. In the treatment area of ​​the tunnel lower anchor section (1) avoiding the contact wire equipment (3), a longitudinal grid steel frame (4) is erected and the grid steel frame (4) is connected to the grouting anchor rod (2). The circumferential reinforcement of the circumferentially connected grid steel frame (4) is arranged, and the grid steel frame (4) is closely attached to the original tunnel lower anchor section lining surface. S4. After erecting the formwork, pour the expansion layer and form a local lining (6). Ensure that the surface of the local lining (6) is in circumferential connection with the unwidened side of the lower anchor section (1), and insert the bracing (7) in the area outside the local lining (6) and in the area where the thickness is insufficient. S5. After the expansion layer has initially set, backfill and grout through the reserved grouting system until it is compacted, and then treat the surface of the lining after pouring. The treatment of the lining surface after pouring in step S5 includes: cleaning the burrs at the joints of the lining after demolding, and spraying epoxy resin on the local lining (6) and within a range of 40cm to 60cm extending outward from the local lining (6). In step S3, the grid steel frame (4) is erected in the widened area of ​​the lower anchor section (1), and the distance between the grid steel frame (4) and the contact wire equipment (3) is greater than 25cm. The widening range of the widened area of ​​the lower anchor section (1) is greater than 25cm; The expansion layer in step S4 is made of micro-expansion self-compacting concrete or micro-expansion grouting binder.

2. The method for partial lining construction for treating severe defects in the lower anchor section of a railway tunnel according to claim 1, characterized in that, In step S2, the grouting anchors (2) are evenly distributed in the reinforcement area of ​​the lower anchor section (1), and the grouting anchors (2) are arranged in a quincunx pattern.

3. The method for partial lining construction for treating severe defects in the lower anchor section of a railway tunnel according to claim 1, characterized in that, In step S2: the concrete at the circumferential section of the lower anchor section (1) is removed and extended 50cm circumferentially to the section of the general anchor section (5). The removal depth matches the thickness of the repaired lining and the lining thickness is greater than 25cm.

4. The method for partial lining construction for treating severe defects in the lower anchor section of a railway tunnel according to any one of claims 1 to 3, characterized in that, In step S4: Drill pins (7) are inserted in the range where the lining thickness is less than the original tunnel lining thickness, and the drill pins (7) are arranged in a grid pattern.

5. The method for partial lining construction for treating severe defects in the lower anchor section of a railway tunnel according to claim 4, characterized in that, In step S3, circumferential ribs with a longitudinal spacing of 1m are set on the grid steel frame (4), and a grouting system is reserved.

6. The method for partial lining construction for treating severe defects in the lower anchor section of a railway tunnel according to claim 4, characterized in that, In step S2, high-pressure air is used to clean the dust inside the steps.

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