A method for constructing a tunnel segment based on mechanical method

Abstract

The application relates to a mechanical construction method based on tunnel segment hole opening, which is used for the construction of a connecting passage. The method comprises the following steps: determining a construction hole opening area of an existing tunnel segment; arranging a grouting area around the construction hole opening area, and performing grouting construction on the grouting area; performing bolt planting on the existing tunnel segment, wherein the bolt planting surrounds the construction hole opening area; performing secondary ring beam pouring around the construction hole opening area and pre-burying a steel ring, wherein the steel ring surrounds the construction hole opening area; performing interval punching construction on the construction hole opening area, so as to weaken the tunnel segment in the construction hole opening area; fixing a steel sleeve pipe on the steel ring; and performing construction operation on the construction hole opening area by using a mine method or a mechanical method. The interval punching construction is adopted in the construction hole opening area, so that the structural strength of the construction hole opening area is weakened, tunneling equipment is facilitated to perform hole opening operation, and the operation stability is improved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for mechanical construction based on tunnel segment opening. Background Technology

[0002] Parallel main tunnels require connecting passages at different locations for material and information exchange, thus creating a three-dimensional interactive channel between adjacent main tunnels. During the construction of the main tunnels, three special lining rings need to be installed at the locations corresponding to the connecting passages. These special lining structures can utilize pre-reserved openings in steel pipe segments or steel-concrete composite pipe segments. In some cases where pre-reserved openings are not feasible, openings must be made in the tunnel segments of the main tunnel.

[0003] The tunnel segment includes internal reinforcement, which consists of inner and outer layers of reinforcement that together form a cage-like steel structure. Both the inner and outer layers of reinforcement contain multiple transverse and longitudinal main bars. Concrete is poured around the reinforcement to create a tunnel segment with high strength and structural stability.

[0004] However, tunnel segments form the wall structure of the main tunnel. Opening holes in the tunnel segments can easily cause irreparable damage to the concrete structure, as well as the possibility of water and sand gushing in during the opening process, which can cause great damage to the tunnel and personnel. Therefore, improvements are needed. Summary of the Invention

[0005] To overcome the problems existing in related technologies, this invention provides a method for mechanical construction based on tunnel segment opening, which solves the technical problems of irreparable damage to tunnel segments and construction safety.

[0006] According to a first aspect of the present invention, a method for constructing a connecting passage using mechanical methods based on tunnel segment opening is provided, the method comprising: Determine the construction opening area for existing tunnel segments; A grouting area is set up around the construction opening area, and grouting is carried out in the grouting area; Rebar is installed on the existing tunnel segments, and the rebar surrounds the construction opening area; A secondary ring beam is poured around the construction opening area, and a steel ring is pre-embedded, the steel ring surrounding the construction opening area; Intermittent drilling was carried out in the construction opening area to weaken the tunnel segments in the construction opening area; The steel sleeve is installed and fixed to the steel ring; Construction work is carried out in the excavation area using mining methods or mechanical methods.

[0007] In one embodiment, the tunnel segment is provided with segment reinforcement, which includes inner layer reinforcement and outer layer reinforcement. Both the inner layer reinforcement and the outer layer reinforcement are provided with multiple transverse main bars and longitudinal main bars. The step of intermittently drilling holes in the construction opening area to weaken the tunnel segments within the construction opening area includes: Multiple first weakening holes are drilled within the area of ​​the construction opening, and the drilling depth of the first weakening holes is a first depth. The main reinforcement of one side of the tunnel segment is located within the drilling depth range of the first weakening holes. Multiple second weakening holes are drilled along the edge of the construction opening area. The drilling depth of the second weakening holes is a second depth. The main reinforcement of the tunnel segment is located within the drilling depth range of the second weakening holes.

[0008] In one embodiment, the intersection point of the transverse main reinforcement and the longitudinal main reinforcement of the inner layer is located within the opening range of the first weakening hole; and / or, the transverse main reinforcement or the longitudinal main reinforcement of the inner layer is located within the opening range of the first weakening hole.

[0009] In one embodiment, the intersection point of the transverse main reinforcement and the longitudinal main reinforcement of the segment is located within the opening range of the second weakening hole; and / or, the transverse main reinforcement or the longitudinal main reinforcement of the segment is located within the opening range of the second weakening hole.

[0010] In one embodiment, the drilling sequence of the second weakening hole adopts a skip drilling method.

[0011] In one embodiment, plain concrete is filled into the construction opening area after the intermittent drilling is carried out.

[0012] In one embodiment, after the construction opening area is drilled at intervals, a water-stop valve is installed, and drilling continues to penetrate the area after the water-stop valve is installed.

[0013] In one embodiment, the step of performing intermittent drilling in the construction opening area and weakening the tunnel segments within the construction opening area includes: The construction opening area is divided into multiple grid areas; Cut and separate the target grid region; After removing the cut target mesh area, fill it with plain concrete. Cut the grid areas one by one until all grid areas are replaced by plain concrete, with the cutting sequence being a skip-cutting process.

[0014] In one embodiment, the step of cutting and separating the target mesh region includes: The edges of the target mesh area are cut in stages using a water drill. Supplement grouting is performed on the areas where water drilling has been performed.

[0015] In one embodiment, the area of ​​the grid region is K in ratio to the area of ​​the construction opening region, where 1 / 30 ≤ K ≤ 1 / 20.

[0016] In one embodiment, ultrasonic testing is performed on the grouting area after grouting to determine whether there are any holes and to require additional grouting.

[0017] In one embodiment, the rebar installation on the existing tunnel segments includes: Grade A anchoring adhesive is used for rebar installation, and the rebar anchorage depth is greater than or equal to 15D, where D is the diameter of the rebar.

[0018] The technical solutions provided by the embodiments of the present invention can include the following beneficial effects: A ring-shaped reinforcing structure formed by a steel ring, rebar installation, and secondary concrete pouring is installed around the construction opening area to ensure the strength of the tunnel segments in the construction opening area. Intermittent drilling is used in the construction opening area to weaken the structural strength of the opening area, facilitating tunneling equipment operation and improving operational stability. A steel sleeve is fixed outside the steel ring to prevent injury to personnel during the opening. Grouting is performed around the construction opening area to stabilize the geological environment outside the tunnel segments, resulting in high operational stability.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] Figure 1 This is a flowchart illustrating a mechanical construction method according to one embodiment.

[0022] Figure 2 This is a schematic diagram of a construction opening area according to one embodiment.

[0023] Figure 3 This is a cross-sectional schematic diagram of a secondary ring beam cast and pre-embedded with steel rings according to one embodiment.

[0024] Figure 4 This is a schematic diagram illustrating, according to one embodiment, the opening of a first weakening hole and a second weakening hole in the construction opening area.

[0025] Figure 5This is a cross-sectional schematic diagram of a first weakening hole being made in the construction opening area, according to one embodiment.

[0026] Figure 6 This is a cross-sectional schematic diagram showing a second weakening hole being made in the construction opening area according to one embodiment.

[0027] Figure 7 This is a schematic diagram illustrating the cutting and separation of a target grid area in a construction opening area, according to one embodiment.

[0028] In the diagram, tunnel segment 10; construction opening area 20; grouting area 30; steel ring 40; ring beam 41; inner ring reinforcement group 42; outer ring reinforcement group 43; first weakening hole 50; second weakening hole 51; segment reinforcement 60; inner layer reinforcement 61; transverse main reinforcement 611; longitudinal main reinforcement 612; outer layer reinforcement 62; grid area 70. Detailed Implementation

[0029] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0030] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present 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, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0031] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] like Figures 1 to 3As shown, this invention provides a mechanical construction method based on tunnel segment opening for the construction of connecting passages. The method includes the following construction steps: S101, Determine the construction opening area 20 of the existing tunnel segment 10. The existing tunnel segment 10 is a concrete segment for constructing the main tunnel. The construction opening area 20 corresponds to the opening area of ​​the connecting passage. The size of the construction opening area 20 is adapted to the opening size of the connecting passage.

[0033] S102, a grouting area 30 is set around the construction opening area 20, and grouting is performed on the grouting area 30. The grouting area 30 is located around the construction opening area 20 and the corresponding external stratum. Grout is injected into the grouting area 30 to improve the strength of the corresponding stratum. Preferably, the grouting area 30 uses a sleeve valve tube / dual-liquid grouting process to reinforce the structural strength of the stratum around the construction opening area 20. Using a sleeve valve tube / dual-liquid grouting improves the flexibility of grouting position control. Optionally, a φ50 sleeve valve tube is used to improve grouting efficiency. Optionally, the spacing of the grouting holes is set according to the stratum conditions. For example, the spacing of the grouting holes is 50 cm. When the stratum is a weak stratum, the spacing of the holes is reduced, such as 35 cm, 40 cm, 45 cm, etc.

[0034] In an optional embodiment, after grouting is completed, ultrasonic testing is performed on the grouting area 30 to determine if there are any voids and to require additional grouting. The grouting reinforcement effect is checked using ultrasonic testing equipment; if voids are found in the grouting area 30, additional grouting reinforcement should be performed.

[0035] S103, rebar is installed on the existing tunnel segment 10, surrounding the construction opening area 20. Holes are drilled in the concrete of the tunnel segment 10 and rebar is installed, wherein Class A rebar anchoring adhesive is injected into the holes and the rebar is inserted for the rebar installation operation. Preferably, the rebar anchorage depth is greater than or equal to 15D, where D is the diameter of the rebar. The rebar is spaced around the construction opening area 20. Optionally, the rebar installation includes an inner ring rebar group 42 and an outer ring rebar group 43 surrounding the construction opening area 20, and the inner ring rebar group 42 and the outer ring rebar group 43 are composed of multiple rebars. Preferably, the inclination angle of the rebar in the inner ring rebar group 42 and the inclination angle of the rebar in the outer ring rebar group 43 are different, that is, the radiation angle of the rebar is different.

[0036] S104, a secondary ring beam 41 is poured around the construction opening area 20, and a steel ring 40 is pre-embedded. The steel ring 40 surrounds the construction opening area 20. After the rebar is installed, the rebar and the steel ring 40 are welded and fixed. The inner diameter of the steel ring 40 is adapted to the tunnel segment 10. Preferably, the steel ring 40 includes a circular tube part and a tapered tube part. The circular tube part is fitted and fixed to the tunnel segment 10, the inner ring rebar group 42 is welded and fixed to the circular tube part, and the outer ring rebar group 43 is welded and fixed to the tapered tube part. Concrete is then poured to form a secondary ring beam 41 around the edge of the construction opening area 20, thereby constructing a secondary lining structure and improving the strength of the opening part of the construction opening area 20. The pre-embedded steel ring 40 provides mechanical construction conditions, and the steel ring 40 can be effectively connected to the mechanically constructed steel pipe section later, and also provides waterproofing.

[0037] S105, intermittent drilling is performed in the construction opening area 20 to weaken the tunnel segments 10 within the construction opening area 20. The tunnel segments 10 in the construction opening area 20 are weakened by drilling, thereby reducing the strength of the tunnel segments 10 in the construction opening area 20.

[0038] S106, the steel sleeve is installed and fixed to the steel ring 40. The steel sleeve is a cylindrical structure with a doorway for personnel or materials to pass through, and is locked by a protective door. The steel sleeve is fixed to the steel ring 40 so that it can be closed in case of an emergency during the excavation of the tunnel segment 10, thus ensuring the safety of the main tunnel construction.

[0039] S107, Mining or mechanical methods are used to carry out construction operations in the construction opening area 20. During the tunneling process, the tunneling equipment can break the tunnel segments 10 in the construction opening area 20 to create a portal. After drilling, the overall strength of the tunnel segments 10 can be reduced to avoid damage to the tunneling cutterhead and increase the tunneling speed.

[0040] Therefore, a steel ring 40, reinforced with rebar and secondary concrete, is installed around the construction opening area 20 to ensure the strength of the tunnel segment 10 within the opening area 20. Intermittent drilling is employed in the construction opening area 20 to weaken its structural strength, facilitating tunneling equipment operations and improving operational stability. A steel sleeve is fixed outside the steel ring 40 to prevent injury to personnel. Grouting is performed around the construction opening area 20 to stabilize the geological environment surrounding the tunnel segment 10, resulting in high operational stability.

[0041] The tunnel segment 10 is equipped with segment reinforcement 60, which is a cage structure formed by connecting multiple steel bars. Concrete pouring encloses the segment reinforcement 60 to form the tunnel segment 10. The segment reinforcement 60 includes inner reinforcement 61 and outer reinforcement 62. Both the inner reinforcement 61 and the outer reinforcement 62 are provided with multiple transverse main bars 611 and longitudinal main bars 612. The tunnel segment 10 has an approximately C-shaped structure, with the inner reinforcement 61 close to the inner arc and the outer reinforcement 62 far away from the inner arc. Example 1

[0042] like Figures 1 to 6 As shown, step S105 is applicable to different geological structures. For example, the method disclosed in this embodiment is applicable to water-rich strata such as silt and gravel strata. Step S105 involves intermittent drilling in the construction opening area 20 to weaken the tunnel segments 10 within the construction opening area 20, including the following steps: S201, Drill multiple first weakening holes 50 within the area of ​​the construction opening 20. The drilling depth of the first weakening holes 50 is a first depth, and the main reinforcement on one side of the tunnel segment 10 is located within the drilling depth of the first weakening holes 50. In this step, the first weakening holes 50 extend from the center of the construction opening 20 to the periphery. Within the drilling depth of the first weakening holes 50, there are transverse main reinforcements 611 and / or longitudinal main reinforcements 612 of the inner layer reinforcement 61. That is, the depth direction is from the inner wall of the tunnel segment 10 outwards. The drilling depth of the first weakening holes 50 is greater than the depth of the inner layer reinforcement 61 and less than the depth of the outer layer reinforcement 62. This reduces the structural strength of the tunnel segment 10 while maintaining the supporting effect of the tunnel segment 10 on the external strata, avoiding technical problems such as external water and sand inrush during the opening process.

[0043] Preferably, the intersection point of the transverse main reinforcement 611 and the longitudinal main reinforcement 612 of the inner layer reinforcement 61 is located within the opening range of the first weakening hole 50. The intersection of the transverse main reinforcement 611 and the longitudinal main reinforcement 612 is located within the opening range of the first weakening hole 50 to simultaneously reduce the structural strength of the transverse main reinforcement 611 and the longitudinal main reinforcement 612. Preferably, either the transverse main reinforcement 611 or the longitudinal main reinforcement 612 of the inner layer reinforcement 61 is located within the opening range of the first weakening hole 50. The first weakening hole 50 cuts through the transverse main reinforcement 611 and / or the longitudinal main reinforcement 612 during drilling, thereby reducing the difficulty of breaking the reinforcement during tunneling and protecting the cutterhead assembly. It is worth mentioning that after the inner layer reinforcement 61 is broken, the tunneling cutterhead can smoothly break through the outer layer reinforcement 62.

[0044] S202, multiple second weakening holes 51 are drilled along the edge of the construction opening area 20. The drilling depth of the second weakening holes 51 is the second depth. The main reinforcement of the tunnel segment 10 is located within the drilling depth range of the second weakening holes 51. The second weakening holes 51 are located at the edge of the construction opening area 20, and the outline formed by the center line of the multiple second weakening holes 51 can match the opening size of the connecting passage.

[0045] The second weakening hole 51 penetrates the tunnel segment 10, thereby reducing the strength of the construction opening area 20, decreasing the cascading impact on other parts of the tunnel segment 10 during cutterhead construction, and improving the safety and reliability of the tunnel segment 10 construction. The second weakening hole 51 can cut off the inner layer reinforcement 61 and the outer layer reinforcement 62, thereby separating most or all of the reinforcing bars inside the construction opening area 20 from the reinforcing bars outside the construction opening area 20, thus improving the construction safety of the construction opening area 20.

[0046] Preferably, the intersection point of the transverse main reinforcement 611 and the longitudinal main reinforcement 612 of the segment reinforcement 60 is located within the opening range of the second weakening hole 51, so as to simultaneously reduce the structural strength of the transverse main reinforcement 611 and the longitudinal main reinforcement 612. Preferably, the transverse main reinforcement 611 or the longitudinal main reinforcement 612 of the segment reinforcement 60 is located within the opening range of the second weakening hole 51. The second weakening hole 51 cuts through the transverse main reinforcement 611 and / or the longitudinal main reinforcement 612 during the drilling process, thereby reducing the difficulty of breakage during tunneling and protecting other parts of the tunnel segment 10 from impact.

[0047] In a preferred embodiment, the drilling sequence of the second weakening hole 51 adopts a skip-drilling method to avoid concentrated local weakening in the construction opening area 20. Skip-drilling means that holes are drilled at predetermined intervals or at predetermined number of intervals along the drilling path of the second weakening hole 51 to ensure balanced weakening of the construction opening area 20. For example, when drilling the second weakening hole 51, the previous drilling position is spaced three to four hole positions apart from the next drilling position, thereby avoiding excessive local weakening.

[0048] Optionally, the second weakening hole 51 is drilled using a two-stage drilling method. For example, the second weakening hole 51 is drilled to a first depth to break the inner reinforcement 61. Afterwards, the construction opening area 20 is drilled intermittently, a water-stop valve is installed, and drilling continues after the water-stop valve is installed. The water-stop valve prevents backflow of water from outside the stratum, thus maintaining the safety of the main tunnel construction.

[0049] In a preferred embodiment, the construction opening area 20 is filled with plain concrete after intermittent drilling. After the second weakening hole 51 is drilled through, it is filled with plain concrete to create a grouting filling effect, which can maintain the structural strength of the tunnel segment 10 and avoid the problem of water and sand inflow from the outside of the stratum. Example 2

[0050] like Figures 1 to 3 , Figure 7 As shown, step S105 is applicable to different geological structures. For example, the method disclosed in this embodiment is applicable to clay and silt geological structures. In step S105, for clay and silt geological structures, another drilling method can be used to weaken the construction opening area 20 of the tunnel segment 10, thereby improving the construction safety of the cutterhead. The process of intermittently drilling the construction opening area 20 and weakening the tunnel segment 10 within the construction opening area 20 includes the following steps: S301, the construction opening area 20 is divided into multiple grid areas 70. The construction opening area 20 is set as a circular opening area. The construction opening area 20 is divided into grid lines by multiple horizontal and vertical lines to form grid lines. Each grid line divides the area into grid areas 70. The area of ​​each grid area 70 is much larger than the area of ​​the drilling size. Preferably, the ratio of the area of ​​the grid area 70 to the area of ​​the construction opening area 20 is K, where 1 / 30 ≤ K ≤ 1 / 20. The division of the grid areas 70 can be based on a comprehensive consideration of construction efficiency, opening size risk, and geological conditions. For example, the construction opening area 20 can be divided into 20, 25, 26, 28, or 30 construction areas by grid lines, which can balance construction efficiency and reduce construction risk.

[0051] S302, the target grid area 70 is cut and separated. A cutting method is used to cut around the edge of the grid area 70 to separate the target grid area 70 from other areas of the tunnel segment 10, so as to facilitate the removal of concrete and reinforcing steel in the cut target grid area 70, forming regional voids.

[0052] S303, after removing the cut target grid area 70, fill it with plain concrete. The plain concrete is filled into the regional voids to bond the plain concrete to the adjacent parts of the tunnel segment 10, which can reduce the structural strength of the construction opening area 20.

[0053] S304, cut the grid areas 70 one by one until all grid areas 70 are replaced by plain concrete, wherein the cutting sequence is a skip-cutting method. The skip-cutting method for the grid areas 70 reduces the disadvantage of excessive local weakening of the tunnel segments 10 and provides sufficient curing time for the plain concrete. Preferably, the starting position for cutting the grid areas 70 is at the edge of the construction opening area 20, so as to weaken the structure from the edge towards the center.

[0054] In step S302, cutting and separating the target mesh region 70 includes: The edge of the target grid area 70 is cut in stages using a water drill. The water drill penetrates the tunnel segment 10 to cut the edge of the segmented area, thereby separating the target grid area 70 from the tunnel segment 10, which facilitates the overall separation of the target grid area 70.

[0055] Supplementary grouting is performed in the area drilled by the water drill. Supplementary grouting during the water drill cutting process maintains the effectiveness of the cut and can proactively avoid construction risks when the hole is breached.

[0056] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0057] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for mechanical construction based on tunnel segment opening, used for the construction of connecting passages, characterized in that the method... include: Determine the construction opening area for existing tunnel segments; A grouting area is set up around the construction opening area, and grouting is carried out in the grouting area; Rebar is installed on the existing tunnel segments, and the rebar surrounds the construction opening area; A secondary ring beam is poured around the construction opening area, and a steel ring is pre-embedded, the steel ring surrounding the construction opening area; The existing tunnel segments are provided with segment reinforcement, which includes inner layer reinforcement on the side close to the inner wall of the existing tunnel segments and outer layer reinforcement on the side away from the inner wall of the existing tunnel segments. Intermittent drilling is performed in the construction opening area to weaken the tunnel segments within the opening area. Specifically, the drilling depth direction is defined as the direction from the inner wall to the outer wall of the existing tunnel segments. Multiple first weakening holes are drilled within the construction opening area. The drilling depth of the first weakening holes is greater than the depth of the inner layer reinforcement but less than the depth of the outer layer reinforcement, thereby breaking the inner layer reinforcement within the opening range of the first weakening holes while preserving the outer layer reinforcement. Multiple second weakening holes are drilled along the edge of the construction opening area. The second weakening holes penetrate the existing tunnel segments to cut off the inner and outer reinforcement within the opening range of the second weakening holes. The steel sleeve is installed and fixed to the steel ring; Mechanical methods were used to carry out construction work in the construction opening area.

2. The method according to claim 1, characterized in that, Both the inner and outer reinforcement layers are provided with multiple transverse main bars and longitudinal main bars.

3. The method according to claim 2, characterized in that, The intersection point of the transverse main reinforcement and the longitudinal main reinforcement of the inner layer is located within the opening range of the first weakening hole; and / or, the transverse main reinforcement or the longitudinal main reinforcement of the inner layer is located within the opening range of the first weakening hole.

4. The method according to claim 2, characterized in that, The intersection point of the transverse main reinforcement and the longitudinal main reinforcement of the segment is located within the opening range of the second weakening hole; and / or, the transverse main reinforcement or the longitudinal main reinforcement of the segment is located within the opening range of the second weakening hole.

5. The method according to claim 2, characterized in that, The drilling sequence for the second weakening hole adopts a skip drilling method.

6. The method according to any one of claims 1 to 5, characterized in that, After the construction opening area is drilled at intervals, plain concrete is filled in.

7. The method according to any one of claims 1 to 5, characterized in that, The drilling of the second weakened hole includes: First, the second weakening hole is drilled to the first depth to break the inner layer reinforcement without penetrating the existing tunnel segment; Install a water-stop valve; and After the water stop valve is installed, continue drilling the second weakening hole until the second weakening hole penetrates the existing tunnel segment.

8. The method according to claim 1, characterized in that, After grouting is performed in the grouting area, ultrasonic testing is conducted to determine whether there are any holes in the grouting area, and additional grouting is performed in the areas where holes are detected.

9. The method according to claim 1, characterized in that, The process of installing rebar on existing tunnel segments includes: Grade A rebar adhesive is used for rebar installation, and the rebar anchorage depth is greater than or equal to 15D, where D is the diameter of the rebar.

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