A new reinforcing structure of shield tunnel based on disassembly-free arc-shaped prefabricated template

Abstract

This utility model discloses a novel shield tunnel reinforcement structure based on a non-removable arc-shaped prefabricated template, comprising a prefabricated template, chemical anchors, and concrete. Each ring of the prefabricated template consists of several prefabricated template pieces. The prefabricated template is arc-shaped and located on the inner side of the tunnel segment. The prefabricated template is fixed to the tunnel segment by the chemical anchors. Concrete is poured between each ring of the prefabricated template and the inner wall of the tunnel segment. The prefabricated template is composed of cement-based prefabricated thin plates arranged relatively inward and outward and reserved truss reinforcement. The advantages of this utility model are: it makes full use of the tunnel clearance space, improves the level of mechanization, and takes into account factors such as material transportation efficiency, equipment lightweighting, and simultaneous construction on multiple working faces. Under the premise of ensuring construction quality, it improves the overall construction efficiency and automation level of shield tunnel structural reinforcement.

Description

Technical Field

[0001] This utility model relates to the technical field of tunnel reinforcement, and in particular to a novel reinforcement structure for shield tunnels based on a non-removable arc-shaped prefabricated template. Background Technology

[0002] Steel lining reinforcement is a commonly used traditional method in subway tunnel reinforcement. It enhances the load-bearing capacity and stiffness of the existing structure by installing steel structures (such as steel rings, steel plates, or steel frames) on the inner wall of the tunnel. Its core principle is to use the high strength characteristics of steel to share the load of the original concrete segments and form a combined force-bearing system with the existing structure through grouting or anchor bolt connection.

[0003] The disadvantages of steel lining reinforcement are as follows:

[0004] 1. Significant space occupation, affecting tunnel operation:

[0005] Clearance encroachment: Traditional steel ring reinforcement requires the installation of steel structures with a thickness of 300-500mm on the inner wall of the tunnel, which leads to a reduction in the effective passage space. For example, after the Beijing Metro Line 10 adopted steel ring reinforcement, the safe clearance between the contact wire and the train dropped to a critical value (<150mm), forcing the train speed to be limited to 40km / h (originally designed to be 60km / h).

[0006] Equipment interference: Protruding parts of the steel lining may affect the passage of equipment such as inspection robots and fire-fighting facilities inside the tunnel, increasing the difficulty of maintenance;

[0007] 2. Low construction efficiency and insufficient mechanization:

[0008] High reliance on manual labor: Steel ring welding, anchor bolt installation and other processes require a large amount of manual operation, and the reinforcement of a single ring (1.2m wide) can take up to 3-5 days;

[0009] The process is complex, involving multiple steps such as surface treatment, steel ring positioning, welding, and grouting. The Shanghai Metro case shows that the rate of repetitive work is as high as 30%.

[0010] Significant construction disruptions: Narrow work areas make it difficult to deploy equipment such as robotic arms, resulting in a construction machinery utilization rate of less than 25%.

[0011] 3. High difficulty in quality control:

[0012] Weld defect risks: Manual welding is prone to problems such as porosity and slag inclusions, and ultrasonic testing shows that the defect rate can reach 5%-8%;

[0013] Uneven grouting density: The fullness of traditional grouting process fluctuates by ±25%, and a 20mm cavity was found in a local area during the inspection of a project in Wuhan.

[0014] Stress concentration risk: Difference in thermal expansion coefficients between steel lining and concrete segments (steel: 12×10) -6 / ℃; Concrete: 10×10 -6 / ℃) may cause interface peeling;

[0015] Long-term durability issues:

[0016] Corrosion risk: The humid environment inside tunnels easily causes steel to rust. After 10 years of use, the steel lining of a subway in a coastal city had a corrosion rate of 0.12 mm / year, resulting in a 15% loss of effective cross-section.

[0017] High maintenance costs: It requires regular application of anti-corrosion coating (every 3-5 years), with a single maintenance cost of approximately 200-300 yuan / ㎡;

[0018] 5. Economic and environmental drawbacks:

[0019] High material costs: steel consumption reaches 120-150 kg / m³;

[0020] Significant carbon emissions: The carbon emissions of the steel lining throughout its entire life cycle are 120-150 kg CO2 / m².

[0021] Therefore, a new type of reinforcement structure for shield tunnels is needed to solve the above problems. Summary of the Invention

[0022] The purpose of this invention is to address the shortcomings of the existing technology by providing a novel shield tunnel reinforcement structure based on a non-removable arc-shaped prefabricated template. This structure consists of a prefabricated template, chemical anchors, and concrete. The prefabricated template is fixed to the tunnel segments by chemical anchors. Concrete is poured between each ring of the prefabricated template and the inner wall of the tunnel segment. Furthermore, the prefabricated template is composed of cement-based prefabricated thin plates arranged relatively inside and outside, and reserved truss reinforcement bars, which improves the construction efficiency and automation of shield tunnel reinforcement.

[0023] The objective of this utility model is achieved through the following technical solution:

[0024] A novel reinforcement structure for shield tunnels based on non-removable arc-shaped prefabricated templates includes prefabricated templates, chemical anchors, and concrete. Each ring of the prefabricated template consists of several prefabricated template pieces. The prefabricated template is arc-shaped and located on the inner side of the tunnel segment. The prefabricated template is fixed to the tunnel segment by the chemical anchors. Concrete is poured between each ring of the prefabricated template and the inner wall of the tunnel segment. The prefabricated template is composed of cement-based prefabricated thin plates arranged relatively inside and outside and reserved truss reinforcement.

[0025] Each ring of the prefabricated template consists of nine prefabricated templates.

[0026] The arc angle of the two precast templates located on both sides of the track bed is 26°, and the arc angle of the other seven precast templates is 36°.

[0027] The reserved truss reinforcement consists of connected circumferential reinforcement, longitudinal reinforcement and radial reinforcement.

[0028] A longitudinal joint is formed between two adjacent prefabricated templates in the circumferential direction, and the longitudinal joint is sealed by a T-shaped prefabricated sealing connector.

[0029] The tunnel segment is pre-embedded with reinforcing bars along its circumference, and the reinforcing bars extend to the outside of the inner wall of the tunnel segment.

[0030] The cement-based precast thin plate has pre-drilled concrete grouting holes.

[0031] The advantages of this utility model are: it makes full use of the tunnel clearance space, improves the level of mechanization, and takes into account factors such as material transportation efficiency, equipment lightweighting, and simultaneous construction on multiple work faces. Under the premise of ensuring construction quality, it improves the overall construction efficiency and automation level of shield tunnel structure reinforcement. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the novel reinforcement structure for shield tunnels according to this utility model;

[0033] Figure 2 This is a partial schematic diagram of the novel reinforcement structure for shield tunnels according to this utility model;

[0034] like Figures 1-2 As shown in the figure, the labels represent:

[0035] 1. Cement-based precast thin slab; 2. Reserved truss reinforcement; 3. Circumferential reinforcement; 4. Longitudinal reinforcement; 5. Radial reinforcement; 6. Longitudinal joint; 7. T-shaped precast sealing connector; 8. Rebar installation; 9. Tunnel segment; 10. Track bed. Detailed Implementation

[0036] The features of this utility model and other related features will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate the understanding of those skilled in the art:

[0037] Example: Figures 1-2As shown, this embodiment relates to a novel reinforcement structure for shield tunnels based on non-removable arc-shaped prefabricated templates. The structure mainly includes prefabricated templates, chemical anchors, and concrete. Each ring of prefabricated templates consists of nine prefabricated template pieces, which are arc-shaped and located inside the tunnel segment 6. The arc angle of the two prefabricated template pieces located on both sides of the track bed 7 is 26°, and the arc angle of the remaining seven prefabricated template pieces is 36°. The prefabricated templates are fixed to the inner wall of the tunnel segment 6 by chemical anchors (not shown in the figure), and concrete is poured between each ring of prefabricated templates and the inner wall of the tunnel segment 6.

[0038] like Figures 1-2 As shown, the precast template consists of cement-based precast thin plates 1 (2cm thick) arranged relatively close to each other and reserved truss reinforcement 2. The reserved truss reinforcement 2 is composed of connected circumferential reinforcement 21, longitudinal reinforcement 22, and radial reinforcement 23. The reserved truss reinforcement 2 of two adjacent circumferential precast templates are interleaved, enhancing the reliability of the connection between them. A longitudinal joint 3 is formed between two adjacent circumferential precast templates, which is sealed by a T-shaped precast sealing connector 4 for sealing the precast templates. The longitudinal ends (i.e., the tunnel extension direction) of each ring of precast template are sealed to the tunnel segment 6 by a precast sealing connector (not shown in the figure) and double-fast cement (not shown in the figure) for sealing the precast template and the tunnel segment 6. Concrete grouting holes (not shown in the figure) are reserved on the cement-based precast thin plates 1 for pouring concrete. Tunnel segment 6 is pre-embedded with reinforcing bars 5 (threaded straight bars) along its circumference. The reinforcing bars 5 extend to the outside of the inner wall of tunnel segment 6 to strengthen the connection between tunnel segment 6 and concrete.

[0039] like Figures 1-2 As shown, this embodiment also includes the following construction methods:

[0040] 1. Pipeline relocation: Before construction, a qualified professional pipeline relocation unit shall prepare a detailed temporary pipeline relocation plan, which shall include pipeline relocation and restoration before construction, monitoring and coordination during construction, and emergency handling of sudden pipeline damage.

[0041] 2. Track Bed Cutting and Removal: To minimize the impact of construction on existing track equipment and facilities, the track bed will be cut without moving the sleepers and tracks. Prior to construction, some track bed concrete will need to be removed on both sides to ensure sufficient construction space. The removal area is the track bed on both sides of the tunnel center, to a depth perpendicular to the tunnel lining segments. Considering the need for uniform steel bracket dimensions for easier processing, a concrete cutting machine will be used to uniformly cut the track bed concrete.

[0042] 3. Treatment of Circumferential and Longitudinal Joints: The manholes of the tunnel segments are sealed. First, the bolt holes of the segments are cleaned and moistened. Then, the prepared quick-repair mortar is filled and leveled, and the area is properly watered and cured before construction. Circumferential and longitudinal joints of the segments within the construction area are sealed. Given that subway tunnel segments are assembled with continuous joints, rigid epoxy is injected into the top sealing section, while elastic epoxy is injected into the remaining circumferential and longitudinal joints. After lateral deformation of the top segments, the outer arc segments may experience point contact stress. Therefore, rigid epoxy is injected into the longitudinal joints on both sides of the sealing block to increase the contact surface of the segments and improve the unfavorable stress distribution. Before the top rigid epoxy filling, the elastic epoxy filling work of the circumferential and longitudinal joints in other locations must be completed first, and the elastic epoxy must be cured before the top rigid epoxy construction can proceed.

[0043] 4. Precast Formwork Assembly: Each ring of precast formwork is divided into nine sections, marked sequentially from left to right (clockwise) as section one to section nine. Sections one and nine are at a 26-degree angle, while the remaining sections are at a 36-degree angle. The surface of each section is a 2cm thick cement-based precast slab, with pre-reserved truss reinforcement bars behind each slab. The reinforcing bars (pre-reserved truss reinforcement bars) extending from the back of each slab are staggered and interwoven with the next slab. Using a lightweight assembly robotic arm, the precast formwork is hoisted into place, and the reinforcing bars behind adjacent slabs are interwoven. Two to three chemical anchors are then inserted, completing the initial assembly and positioning of the formwork.

[0044] 5. Anchor bolt installation: After the initial positioning of the precast template is completed, the precast template and the inner wall of the segment are rigidly connected by installing chemical anchor bolts. Each precast template needs to be implanted with 6 16cm chemical anchor bolts and 8 20cm chemical anchor bolts.

[0045] 6. On-site casting: T-shaped precast sealing connectors are used to fill the longitudinal joints of the precast formwork to seal the gaps and ensure a tight seal. The gaps between the precast formwork (both longitudinal ends) and the pipe segments are sealed using a combination of precast sealing connectors and quick-setting cement. Concrete grouting holes are pre-drilled on the sides of each precast formwork to create a closed space between the formwork and the pipe segments. High-strength concrete mixed on-site is poured in batches through the pre-drilled grouting holes, filling from bottom to top. The grouting holes are then sealed after ensuring a dense filling.

[0046] 7. Pipeline and track bed restoration: The original relocated pipelines and part of the track bed in the tunnel will be restored according to the design requirements.

[0047] The beneficial technical effects of this embodiment are: making full use of the tunnel clearance space, improving the level of mechanization, and taking into account factors such as material transportation efficiency, equipment lightweighting, and simultaneous construction on multiple work faces, thereby improving the overall construction efficiency and automation level of shield tunnel structure reinforcement while ensuring construction quality.

[0048] Although the above embodiments have described the concept and embodiments of the present invention in detail with reference to the accompanying drawings, those skilled in the art will recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, and therefore will not be elaborated here.

Claims

1. A novel reinforcement structure for shield tunnels based on non-removable arc-shaped prefabricated templates, characterized in that... It includes precast templates, chemical anchors, and concrete. Each ring of the precast template consists of several precast template pieces. The precast template is arc-shaped and located on the inner side of the tunnel segment. The precast template is fixed to the tunnel segment by the chemical anchors. The concrete is poured between the precast template and the inner wall of the tunnel segment in each ring. The precast template is composed of cement-based precast thin plates and reserved truss reinforcements arranged opposite to each other.

2. The novel reinforcement structure for shield tunnels based on non-removable arc-shaped prefabricated templates as described in claim 1, characterized in that... Each ring of the prefabricated template consists of nine prefabricated templates.

3. A novel reinforcement structure for shield tunnels based on a non-removable arc-shaped prefabricated template as described in claim 2, characterized in that... The arc angle of the two precast templates located on both sides of the track bed is 26°, and the arc angle of the other seven precast templates is 36°.

4. The novel reinforcement structure for shield tunnels based on non-removable arc-shaped prefabricated templates as described in claim 1, characterized in that... The reserved truss reinforcement consists of connected circumferential reinforcement, longitudinal reinforcement and radial reinforcement.

5. A novel reinforcement structure for shield tunnels based on a non-removable arc-shaped prefabricated template as described in claim 1, characterized in that... A longitudinal joint is formed between two adjacent prefabricated templates in the circumferential direction, and the longitudinal joint is sealed by a T-shaped prefabricated sealing connector.

6. A novel reinforcement structure for shield tunnels based on a non-removable arc-shaped prefabricated template as described in claim 1, characterized in that... The tunnel segment is pre-embedded with reinforcing bars along its circumference, and the reinforcing bars extend to the outside of the inner wall of the tunnel segment.

7. A novel reinforcement structure for shield tunnels based on a non-removable arc-shaped prefabricated template as described in claim 1, characterized in that... The cement-based precast thin plate has pre-drilled concrete grouting holes.

Images