Combined anti-upheaval reinforcing method for existing large-span operation open cut tunnel

Abstract

The invention discloses a combined anti-upheaval reinforcing method for an existing large-span operation open cut tunnel. The combined anti-upheaval reinforcing method comprises the following steps that filling soil at the top of the tunnel and between fender posts is reinforced through grouting; arranging a top beam and pouring a straining beam; uplift piles are arranged on the outer sides of the fender posts, and bearing platform pile foundations are constructed; constructing a coping beam in an alternate mode, penetrating through the fender posts through reinforcing steel bars and anchoring into the uplift piles; soil bodies on the outer sides of the existing fender posts are symmetrically excavated step by step to form grooves, longitudinal beams are built in the grooves in a segmented mode, and reinforcing steel bars of the longitudinal beams are anchored into the existing fender posts; a social corridor structure bearing platform and a bottom plate structure on the outer side of the groove are symmetrically excavated and poured step by step; excavating step by step and pouring a structural bottom plate on the inner side of the enclosure structure; the fender posts are dismantled to connect the channel structures into a whole, and an upper structure is constructed. The newly-built coping beams, the longitudinal beams and the uplift piles are coordinated and matched to form an integral uplift-resistant structure with the existing fender posts, uplift-resistant acting force can be efficiently transmitted to a soil layer on the lower side, and therefore uplift deformation of the open-cut tunnel is effectively controlled.

Description

Technical Field

[0001] The invention relates to the field of rail transit open-cut tunnel engineering, and in particular to a combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation. Background Art

[0002] With the acceleration of China's urbanization process, the growth rate of urban land use is much lower than the growth rate of urban population, and the limited urban surface land resources can no longer meet people's demand for living space. In order to alleviate the shortage of urban land resources, the development and utilization of underground space has gradually become an important direction of urban planning. In the development and utilization of underground space, subway tunnels are important infrastructure for urban transportation, and their construction and operation play a key role in the efficiency and safety of urban transportation. However, with the increase in urban underground projects, new underground projects adjacent to existing subway tunnels have also increased. Such projects need to fully consider the impact on existing underground structures in the planning and design stages to avoid adverse effects on surrounding structures during construction.

[0003] In the prior art, when underground engineering construction is carried out above or on both sides of an adjacent operating subway tunnel, it usually involves large-scale soil unloading and structural disturbance. These disturbances can cause uplift, displacement and deformation of the tunnel, thus affecting the safety and operational efficiency of the tunnel. At present, there is a lack of effective anti-uplift reinforcement measures for ultra-long, close and parallel soil unloading construction scenarios, especially in the case of adjacent large-span open-cut subway tunnels in operation, which makes it difficult to meet the safety and stability of the tunnel structure and the normal operation requirements of the train. In addition, the stability and economy of the existing methods during the construction process are also insufficient, and they cannot effectively cope with complex engineering conditions. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation. The method forms an integral anti-uplift structure with the existing retaining piles through the coordinated cooperation of newly built capping beams, longitudinal beams and anti-pullout piles. The anti-uplift force can be efficiently transmitted to the underlying soil layer, thereby effectively controlling the uplift deformation of the open-cut tunnel and ensuring the safety and stability of the tunnel structure, while having the advantages of low construction cost and fast construction speed.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation, comprising the following steps:

[0007] S1, grouting to reinforce the top of the existing tunnel structure and the fill between the existing retaining piles to form a soil reinforcement area;

[0008] S2, a cap beam is set on the top of the existing retaining piles, and a tension beam is cast between the cap beams on both sides;

[0009] S3, driving anti-pullout piles outside the existing retaining piles, and constructing pile foundations at the bottom of the caps on both sides of the social corridor at the same time;

[0010] S4, skip warehouse construction of the top beam, chisel out part of the concrete of the existing retaining piles but retain the steel bars, pass the steel bars of the top beam through the existing retaining piles and anchor them into the pull-out piles, pour C20 plain concrete to the bottom of the foundation pit of the social corridor, and set a counterweight on the top of the top beam after the strength of the top beam reaches the design;

[0011] S5, symmetrically excavate the soil outside the existing retaining piles in steps to form a trench, and build longitudinal beams in sections in the trench, anchor the steel bars of the longitudinal beams into the existing retaining piles, and backfill with C20 plain concrete; after the longitudinal beams reach the design strength, symmetrically cast the structural bottom plate in the trench in sections, and add counterweights on top of the bottom plate after it reaches the design strength;

[0012] S6, symmetrically excavate and cast the social corridor structure pedestal and bottom plate structure outside the trench in steps, and add counterweight after the bottom plate reaches the design strength;

[0013] S7, excavate and cast the inner structural bottom plate of the enclosure structure in steps, and add counterweight after the bottom plate reaches the designed strength;

[0014] S8, remove the existing retaining piles to connect the channel structure into a whole, and construct the superstructure. The counterweight can be removed only after the superstructure reaches the designed strength.

[0015] Preferably, in step S3, there is a gap between the existing retaining piles and the anti-pullout piles, and the anti-pullout piles are constructed using fully-rotating bored casings.

[0016] Preferably, in step S4, the capping beam and the pull-out piles are evenly arranged, the capping beam passes through the existing retaining piles during the construction process, and the steel bars at both ends of the capping beam pass through the existing retaining piles and are anchored in the pull-out piles to form a stable overall reinforcement structure.

[0017] Preferably, in step S5, the longitudinal beam is cast outside the existing retaining piles, the longitudinal beam is effectively connected to the existing retaining piles, and the longitudinal beam is used to connect a plurality of pull-out piles together.

[0018] Preferably, the existing retaining piles are in direct contact with the longitudinal beams, and the contact surfaces are roughened and coated with an interface agent layer.

[0019] Preferably, the upper parts of both ends of the top beam are in contact with the lower part of the longitudinal beam on one side close to the existing retaining piles, and the contact surface is roughened and coated with an interface agent layer, and the steel bars at both ends of the top beam pass through the contact surface.

[0020] Preferably, the node connections between the existing retaining piles and the longitudinal beams are made by embedding reinforcement, and the contact surfaces are roughened and coated with an interface agent layer.

[0021] Preferably, the length direction of the longitudinal beam is along the extension direction of the existing tunnel.

[0022] Preferably, the cross-section of the top beam is rectangular.

[0023] Preferably, in step S8, the construction of the superstructure adopts modular assembly.

[0024] The beneficial effects of the present invention are as follows: The combined anti-uplift reinforcement method of the existing large-span open-cut tunnel provided by the present invention adopts a combination of a capping beam and an existing retaining pile to form a combined integral anti-uplift structure, which transmits the anti-uplift force to the lower soil layer through the capping beam, the existing retaining pile, the longitudinal beam, and the pull-out pile in sequence, effectively limiting the deformation of the foundation soil and preventing the uplift and instability of the tunnel structure. The design of the present invention is particularly suitable for complex engineering scenes of open-cut tunnels. It utilizes the stable characteristics of the existing retaining piles to form an integral reinforcement system with the newly built structure, thereby achieving the safety of the construction and the stability of the tunnel. At the same time, the construction scheme of the present invention is both economical and efficient, reducing the impact of the construction on the operation of the existing subway tunnel, and providing a strong guarantee for the normal operation of the tunnel under the construction environment. Compared with the traditional anti-floating frame structure, the present invention has higher economy and practicality while ensuring the safety of the tunnel. With the increasing demand for urban underground space development, the present invention can be widely used in the construction scenes of ultra-long adjacent parallel foundation pit excavation and adjacent open-cut tunnels, and has a high promotion value and market prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Attached Figure 1 It is a cross-sectional schematic diagram of the combined anti-uplift structure of the existing large-span open-cut tunnel of the present invention;

[0026] Attached Figure 2 It is a top view of the combined anti-uplift structure of the existing large-span open-cut tunnel of the present invention;

[0027] Attached Figure 3 It is a schematic diagram of the continuous reinforcement connection of the capping beam, the anti-pulling pile, the longitudinal beam and the existing retaining piles of the present invention;

[0028] Attached Figure 4 This is a cross-sectional view of the excavation of the capping beam of the present invention;

[0029] Attached Figure 5 is a longitudinal sectional view of the combined anti-uplift structure of the present invention;

[0030] Figure numerals: 1-cap beam; 2-tension beam; 3-soil reinforcement area; 4-longitudinal beam; 5-capping beam; 6-existing tunnel; 7-existing retaining piles; 8-pull-out piles. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the present invention.

[0032] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0033] See also Figure 1-5 This embodiment discloses a combined anti-uplift reinforcement method for an existing large-span open-cut tunnel, comprising the following steps:

[0034] S1, grouting to reinforce the fill soil between the top of the existing tunnel 6 structure and the existing retaining piles 7 to form a soil reinforcement area 3.

[0035] In this step, the grouting material fills the voids inside the soil to form a soil reinforcement zone 3, thereby enhancing the anti-uplift capability and ensuring that the soil will not be deformed due to disturbance during the subsequent construction process.

[0036] S2, a cap beam 1 is arranged on the top of the existing retaining pile 7, and a tension beam 2 is cast between the cap beams 1 on both sides.

[0037] In this step, the overall rigidity of the top of the retaining pile 7 is improved by setting the cap beam 1, and then the cap beams 1 on both sides are effectively connected by pouring the tension beam 2, further enhancing the anti-uplift ability of the overall structure. The combination of the cap beam 1 and the tension beam 2 makes full use of the bearing capacity of the upper part of the soil and effectively disperses the construction load.

[0038] S3, anti-pullout piles 8 are driven outside the existing retaining piles 7, and at the same time, pile foundations at the bottom of the pedestals on both sides of the social corridor are constructed.

[0039] In this step, the overall anti-uplift ability is further improved by evenly arranging the pull-out piles 8 on the outside of the existing retaining piles 7. The pull-out piles 8 can effectively constrain the vertical displacement of the soil and bear the upward pull force during the construction process. In addition, the pile foundations at the bottom of the pedestals on both sides of the social corridor are constructed at the same time to provide the necessary basic support for the subsequent social corridor structure. There is a gap between the existing retaining piles 7 and the pull-out piles 8. The reserved gap effectively avoids the structural disturbance and damage to the retaining piles 7 during the construction of the pull-out piles 8. The pull-out piles 8 are constructed with a full-rotation drilled casing. The use of the full-rotation drilled casing can ensure the accuracy and verticality of the pull-out pile 8 construction, while reducing the stratum disturbance during the construction process, enhancing the bearing capacity of the pull-out piles 8, and providing a guarantee for the overall stability of the subsequent structure. The social corridor is located in the underground space and is used to connect underground passages in different areas of the city. It is usually used to facilitate the passage of pedestrians or small vehicles, effectively reducing ground traffic pressure.

[0040] S4, construct the top beam 5 by skipping the warehouse, remove part of the concrete of the existing retaining piles 7 but keep the steel bars, pass the steel bars of the top beam 5 through the existing retaining piles 7 and anchor them into the pull-out piles 8, pour C20 plain concrete to the bottom of the foundation pit of the social corridor, and after the strength of the top beam 5 reaches the design, set a counterweight on its top.

[0041] In this step, the method of skipping the construction of the top beam 5 can effectively avoid the disturbance of the tunnel and soil body caused by one-time large-scale excavation. By chiseling away part of the concrete of the retaining piles 7, the steel bars of the top beam 5 are directly passed through the retaining piles 7 and anchored into the pull-out piles 8 to form a stable connection structure. The setting of the counterweight further enhances the anti-uplift ability and ensures the safety of the existing tunnel 6. The top beam 5 and the pull-out piles 8 are evenly arranged in correspondence. During the construction process, the top beam 5 passes through the existing retaining piles 7, and the steel bars at both ends of the top beam 5 pass through the existing retaining piles 7 and anchored into the pull-out piles 8, thereby connecting the retaining piles 7, the pull-out piles 8 and the top beam 5 as a whole, forming a stable overall reinforcement structure, and enhancing the anti-uplift performance of the overall structure. S5, symmetrically excavate the soil outside the existing retaining piles 7 in steps to form a trench, and build the longitudinal beam 4 in sections in the trench, anchor the steel bars of the longitudinal beam 4 into the existing retaining piles 7, and backfill with C20 plain concrete; after the longitudinal beam 4 reaches the design strength, symmetrically cast the structural bottom plate in the trench in sections, and add counterweights on top of the bottom plate after it reaches the design strength.

[0042] In this step, the soil and structure are ensured to be stable by excavating the trench step by step. The longitudinal beam 4 is constructed in the trench, and the existing retaining piles 7 are anchored by steel bars to form an overall anti-uplift structure. The bottom plate casting and counterweight further enhance the stability. In addition, the longitudinal beam 4 is cast outside the existing retaining piles 7. The longitudinal beam 4 is along the extension direction of the existing tunnel 6. The longitudinal beam 4 is effectively connected to the existing retaining piles 7. The longitudinal beam 4 is used to connect multiple pull-out piles 8 together, which further enhances the load-bearing capacity and stability of the pull-out system, and contributes to the safety and durability of the overall structure during construction and operation.

[0043] S6, symmetrically excavate and cast the social corridor structure pedestal and bottom plate structure outside the trench in steps, and add counterweight after the bottom plate reaches the designed strength.

[0044] In this step, the balance of construction can be ensured by symmetrically excavating and constructing the pedestal and base plate structure of the social corridor in steps. After the base plate strength reaches the requirement, the weight is added in time to effectively control the uplift and deformation of the soil.

[0045] S7, excavate and cast the inner structural bottom plate of the retaining structure in steps, and add counterweight after the bottom plate reaches the designed strength.

[0046] In this step, during the construction of the bottom plate inside the enclosure structure, a step-by-step excavation method is adopted, which can not only ensure the safety of the construction process, but also reduce the disturbance to the existing tunnel 6. Adding counterweight after the bottom plate construction is completed can further reduce the deformation risk of the tunnel structure.

[0047] S8, dismantle the existing retaining piles 7 to connect the channel structure into a whole, and construct the superstructure. The counterweight can be dismantled only after the superstructure reaches the designed strength.

[0048] In the last step, the existing retaining piles 7 are removed to connect the originally scattered structures into a whole. After the superstructure is constructed, the counterweight is removed after it reaches the designed strength, thereby ensuring the stability and safety of the overall structure. The construction of the superstructure can be modularized. The modular assembly construction method prefabricates the superstructure into multiple modular components and assembles them quickly on site, which not only shortens the construction period, but also reduces the risk of disturbance to the existing tunnel 6 during construction, while improving the safety of construction and the controllability of quality control.

[0049] Through the above steps, the method of the present invention achieves effective anti-uplift reinforcement while ensuring the safe operation of the existing tunnel 6, and has significant practicality and economy.

[0050] Furthermore, the existing retaining piles 7 and the longitudinal beams 4 are in direct contact, and the contact surface is roughened and coated with an interface agent layer. Specifically, the node connection between the existing retaining piles 7 and the longitudinal beams 4 is performed by anchoring steel bars. By bringing the existing retaining piles 7 into direct contact with the longitudinal beams 4, a firm node connection is formed. The roughening process can increase the roughness of the contact surface, improve the bonding force between concrete and steel bars, and increase the overall shear strength of the structure. Applying the interface agent layer further enhances the bonding performance of the contact surface, ensuring the stability and bearing capacity of the connection node. During the node connection process, the anchoring technology effectively improves the connection strength between the existing retaining piles 7 and the longitudinal beams 4 by anchoring the steel bars into the contact surface.

[0051] In this embodiment, the upper parts of both ends of the capping beam 5 are in contact with the lower part of the longitudinal beam 4 on one side close to the existing retaining pile 7, and the contact surface is roughened and coated with an interface agent layer, and the steel bars at both ends of the capping beam 5 pass through the contact surface. The two ends of the capping beam 5 are connected to the longitudinal beam 4 through steel bar anchoring, which can effectively transfer the load borne by the capping beam 5. The contact surface is roughened and treated with an interface agent, which further enhances the bonding force and deformation resistance of the contact area, thereby ensuring the overall stability of the capping beam 5 and the longitudinal beam 4. Specifically, the cross-section of the capping beam 5 can be rectangular. The rectangular cross-section design of the capping beam 5 can better adapt to the distribution characteristics of the soil and load above the tunnel. Its flat cross-sectional shape helps to improve construction efficiency, and the rectangular cross-section has high bending stiffness and bearing capacity, thereby enhancing the structural stability of the entire reinforcement system.

[0052] In this embodiment, step S4 and step S5 are key, which realizes the combined use of the capping beam 5, the existing retaining piles 7, the pull-out piles 8 and the longitudinal beam 4. Through this combined design, not only can the stability of the existing tunnel structure be effectively enhanced, but also an efficient anti-uplift reinforcement system can be formed. In step S4, the capping beam 5 passes through the existing retaining piles 7 and is anchored into the pull-out piles 8, forming a stable force transmission path, and the setting of the longitudinal beam 4 in step S5 connects multiple pull-out piles 8 together, effectively dispersing and transmitting the load. In addition, the longitudinal beam 4 and the capping beam 5 are in contact and connected together by steel bars, further enhancing the integrity and synergy between the two. This structural design enables the various reinforcement components to cooperate with each other, significantly improving the deformation resistance and stability of the entire structure, and ensuring the safety and operational reliability of the existing tunnel under complex construction conditions. This systematic anti-uplift design has the advantages of high construction efficiency and significant effect, and provides reliable technical support and reference value for similar projects.

[0053] In summary, the present invention proposes a combined anti-uplift reinforcement method for an existing large-span open-cut tunnel, and forms an efficient anti-uplift reinforcement system through the comprehensive use of a capping beam 5, existing retaining piles 7, anti-pulling piles 8, longitudinal beams 4 and other components. Specifically, the soil between the existing tunnel 6 and the retaining piles 7 is reinforced by grouting technology to form a soil reinforcement area 3; the overall rigidity is further enhanced by setting a crown beam 1 on the top of the retaining pile 7 and casting a tension beam 2; at the same time, through the design of the capping beam 5, its steel bars pass through the retaining piles 7 and anchor into the anti-pulling piles 8 to form a stable connection structure, and contact with the longitudinal beam 4 and connect through the steel bars to form an overall reinforcement structure. This structure can effectively limit the uplift of the soil and ensure the stability and safety of the construction area. Through the above-mentioned structural design and construction method, the bearing capacity of the existing retaining piles 7 is fully utilized, and its anti-uplift force is sequentially transmitted to the lower soil layer through the capping beam 5, the existing retaining piles 7, the longitudinal beam 4 and the anti-pulling piles 8, thereby effectively controlling the uplift deformation of the existing tunnel 6 and ensuring the stability of the tunnel structure and operational safety. In addition, the modular construction method significantly reduces construction costs and time, while reducing construction risks, and has high practical value. With the further development of urban underground space, the reinforcement method proposed in the present invention can be widely used in the construction of large-scale foundation pits with super-long adjacent parallel tunnels, especially in engineering projects that need to cross existing operating open-cut tunnels 6, showing extremely high adaptability.

[0054] The present invention has the advantages of low project cost, good anti-uplift effect, and low construction risk. In addition, by reinforcing the excavated foundation pit, it can reduce the impact on surface structures and existing tunnel operations and reduce social impact. Compared with conventional reinforcement schemes, the present invention effectively utilizes existing retaining piles, significantly reduces project costs, and ensures construction safety. With the support of the implementation of technical measures, the present invention has a good prospect for promotion and application, and is particularly suitable for the development of urban underground space, involving situations involving close tunnel construction. Its simple, economical and efficient reinforcement method provides a reliable solution for similar projects, and has broad application value and market potential.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the above embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the above embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A combined anti-uplift reinforcement method for an existing large-span open-cut tunnel, characterized in that: The following steps are involved: S1, grouting to reinforce the fill between the top of the existing tunnel (6) structure and the existing retaining piles (7) to form a soil reinforcement area (3); S2, setting a cap beam (1) on the top of the existing retaining pile (7), and casting a tension beam (2) between the cap beams (1) on both sides; S3, driving anti-pullout piles (8) outside the existing retaining piles (7), and at the same time constructing the pile foundations at the bottom of the caps on both sides of the social corridor; S4, skipping the construction of the top beam (5), chiseling away part of the concrete of the existing retaining piles (7) but retaining the steel bars, passing the steel bars of the top beam through the existing retaining piles (7) and anchoring them into the pull-out piles (8), pouring C20 plain concrete to the bottom of the foundation pit of the social corridor, and setting a counterweight on the top of the top beam (5) after the strength reaches the design; S5, symmetrically excavating the soil outside the existing retaining pile (7) in steps to form a trench, and constructing longitudinal beams in sections in the trench, anchoring the steel bars of the longitudinal beams (4) into the existing retaining pile (7), and backfilling with C20 plain concrete; After the longitudinal beam (4) reaches the design strength, the structural bottom plate in the groove is cast symmetrically in sections, and a counterweight is added on top of the bottom plate after the bottom plate reaches the design strength; S6, symmetrically excavate and cast the social corridor structure pedestal and bottom plate structure outside the trench in steps, and add counterweight after the bottom plate reaches the design strength; S7, excavate and cast the inner structural bottom plate of the enclosure structure in steps, and add counterweight after the bottom plate reaches the designed strength; S8, dismantle the existing retaining piles (7) to connect the channel structure into a whole, and construct the superstructure. The counterweight can be dismantled only after the superstructure reaches the designed strength.

2. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 1 is characterized in that: In the step S3, there is a gap between the existing retaining pile (7) and the anti-pulling pile (8), and the anti-pulling pile (8) is constructed using a fully-rotating bored casing.

3. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 2 is characterized in that: In step S4, the top beam (5) and the pull-out piles (8) are evenly arranged correspondingly, the top beam (5) passes through the existing retaining piles (7) during the construction process, and the steel bars at both ends of the top beam (5) pass through the existing retaining piles (7) and are anchored in the pull-out piles (8), forming a stable overall reinforcement structure.

4. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 3 is characterized in that: In the step S5, the longitudinal beam (4) is cast outside the existing retaining pile (7), the longitudinal beam (4) and the existing retaining pile (7) are effectively connected, and the longitudinal beam (4) is used to connect a plurality of pull-out piles (8) together.

5. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 4 is characterized in that: The existing retaining piles (7) are in direct contact with the longitudinal beams (4), and the contact surfaces are roughened and coated with an interface agent layer.

6. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 5 is characterized in that: The upper parts of both ends of the top beam (5) are in contact with the lower part of the longitudinal beam (4) on one side close to the existing retaining pile (7), and the contact surface is roughened and coated with an interface agent layer, and the steel bars at both ends of the top beam (5) pass through the contact surface.

7. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 6 is characterized in that: The node connection between the existing retaining piles (7) and the longitudinal beams (4) is performed by embedding reinforcement.

8. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 7 is characterized in that: The length direction of the longitudinal beam (4) is along the extension direction of the existing tunnel (6).

9. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 1 is characterized in that: The cross section of the top pressure beam (5) is rectangular.

10. The combined anti-uplift reinforcement method for an existing large-span open-cut tunnel in operation according to claim 1, characterized in that: In step S8, the construction of the superstructure adopts modular assembly.

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