Partition processing method for preventing oversized-diameter shield tunnel segment from floating upwards

Abstract

The invention discloses a zoning treatment method for preventing oversized-diameter shield tunnel segments from floating, which comprises the following steps: step 1, arranging an expansion film bag on the outer side of an upper segment, and pouring cement-water glass quick-setting slurry into the film bag through a sleeve to enable the cement-water glass quick-setting slurry to expand to form a pressure arch; 2, pre-stressed anchor rods are arranged on the lower segment, and pressure-bearing gaskets are arranged; 3, after construction in the step 1 and the step 2 is completed, grouting is conducted on the middle segment, cement-water glass double-liquid slurry is injected from the middle segment, the slurry diffuses from the middle to the vertical direction in a fan shape, and the space behind the segment wall is fully filled; the grouting body, a film bag pressure arch formed on the upper portion and an anchor rod anti-pulling system arranged on the lower portion jointly form a continuous bearing structure to cooperatively restrain overall floating of the duct piece.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of shield construction, in particular to a partitioned treatment method for preventing the floating of a super-large-diameter shield tunnel segment. BACKGROUND

[0002] In recent years, with the rapid development of urban underground space, the construction mileage of tunnels as major transportation hubs has increased year by year, and shield tunnels have gradually evolved towards large diameters, especially urban underground highway tunnels and railway tunnels, with super-large cross sections with diameters greater than 14 m being increasingly widely used. However, the problem of overall floating of segments in super-large-diameter shield tunnel construction has become increasingly prominent. The size of the buoyancy acting on the segment is in a square relationship with the diameter, resulting in a buoyant force acting on the segment far exceeding the weight of the segment. The single-fluid grouting technology traditionally applied to 6m-level tunnels has little effect in super-large-diameter shield tunnels due to factors such as a relatively long setting time and difficulty in controlling the spread of the grout. Overall floating of segments can easily cause segment ring misalignment and joint opening; continuous excessive or uneven deformation can significantly reduce the load-bearing capacity and waterproof performance of the segment lining, and in severe cases, can cause structural damage and threaten the long-term operation safety of the tunnel. The existing technology has obvious deficiencies in long-term control of the overall floating of segments in super-large-diameter shield tunnels, for example: patent CN119686776A proposes a device and method for preventing segment displacement using membrane bag grouting, but it mainly provides pressure by arranging a membrane bag grouting body outside the segment, and this scheme focuses on local area floating control. For the lower segment area, the pressure provided by the membrane bag grouting body is in the same direction as the buoyancy, and cannot generate the required counterforce or restraint to resist the floating of the lower segment, so it is difficult to solve the problem of floating of the lower segment and even the overall segment ring in super-large-diameter shield tunnels; patent CN118911710A proposes a simultaneous grouting method for controlling segment floating by grouting double-fluid grout in the upper half of the segment and inert grout in the lower half, but this method mainly relies on the passive restraint force provided by the set grout. For super-large-diameter shield tunnels, the huge buoyancy requires a very high restraint force, and the spread of the grout is significantly affected by factors such as ground permeability and grouting pressure, making it difficult to ensure the formation of a uniform, continuous, and sufficiently strong and stiff reinforcement layer in the target area; in addition, the single reliance on grout restraint provides limited anti-float force and stability, which is easily affected by grout performance and ground conditions, making it difficult to reliably and long-term inhibit the overall floating of the segment.

[0003] In summary, the existing technology lacks targeted measures and has insufficient long-term stability and reliability for the overall floating problem of super-large-diameter shield tunnel segments, especially the huge buoyancy characteristics. Single technical means cannot form an effective and coordinated overall anti-float system. SUMMARY

[0004] The application aims to overcome the limitations of the prior art, such as lack of targeted measures for the overall floating of the super-large-diameter shield tunnel segment and insufficient long-term stability, and provides a layered control method for preventing the floating of the super-large-diameter shield tunnel segment. The method innovatively constructs a layered control system of 'upper membrane bag pressure- lower anchor anti-pulling-mid grouting reinforcement': the membrane bag is arranged on the upper segment to form a pressure arch to offset the floating force acting on the segment, the anchor is arranged on the lower segment to provide anti-pulling resistance, and the cement grouting is performed on the middle segment for filling and reinforcement. The system can work together to effectively inhibit the overall floating of the super-large-diameter shield tunnel segment, fill the gap of targeted solutions, and improve the operation safety of the tunnel in the whole life cycle.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows: A layered treatment method for preventing the floating of a super-large-diameter shield tunnel segment, comprising the following steps: The shield machine cutterhead excavates for a distance to ensure that the construction area is out of the influence range of the excavation disturbance, and the segment assembly of the shield tail area is completed, (1) An inflatable membrane bag is arranged on the outer side of the upper segment, cement-water glass quick-setting slurry is injected into the membrane bag through a sleeve to make the membrane bag expand to form a pressure arch, vertical pressure is applied to offset the floating force acting on the segment, and the membrane bag expands to fill the space behind the wall of the area where the membrane bag is located to inhibit the lifting of the segment; (2) A pre-stressed anchor is arranged on the lower segment, the anchor provides anti-pulling force to offset the floating load acting on the segment, and a pressure pad is arranged to convert the concentrated point load of the anchor into uniform surface load on the surface of the segment to improve the stability of the overall structure of the tunnel; (3) After the completion of steps (1) and (2), synchronous grouting is performed on the middle segment as the shield machine excavates, and cement-water glass double-liquid slurry is injected from the middle segment; the slurry spreads in a fan shape upward and downward from the middle segment to fully fill the space behind the wall of the segment. The grouting body, the membrane bag pressure arch formed on the upper part and the anchor anti-pulling system arranged on the lower part jointly form a continuous bearing structure to cooperatively inhibit the overall floating of the segment and ensure the long-term stability of the tunnel structure.

[0006] Preferably, in step 1, the membrane bag grouting of the upper segment adopts a separate grouting system.

[0007] Preferably, in step 1, the inlet end of the membrane bag is fixedly connected with the outlet end of the sleeve through a flange and bolts to form a membrane bag grouting device, the membrane bag body is folded and wrapped around the end of the sleeve, and a plurality of slurry outlets are formed on the sleeve wall. Preferably, when the membrane bag is applied, the end of the sleeve wrapped around the membrane bag is inserted into the lifting hole reserved in the pipe piece, and after the end of the sleeve contacts the pipe piece wall, the cement-water glass double-liquid slurry is pumped through the flange connection of the tee grouting pipe at the inlet end of the sleeve, and the slurry is uniformly injected and filled into the internal space of the membrane bag through the outlet hole of the sleeve wall, prompting the membrane bag to expand and form a certain volume and strength of the weight body to offset the buoyancy and inhibit the pipe piece from floating up, while filling the space behind the pipe piece wall and eliminating the space for the pipe piece to float up; Optionally, in step 1, the membrane bag can be individually folded and pushed to the predetermined position of the outer wall of the pipe piece through the lifting hole reserved in the pipe piece. The membrane bag is pre-sewn with high-strength nylon webbing, the nylon webbing is pulled back to the inside of the pipe piece from the lifting hole, and is locked and fixed to make the membrane bag tightly adhere to the outer wall of the pipe piece, and then the cement-water glass double-liquid slurry is injected into the membrane bag through the grouting hole of the membrane bag by the tee grouting pipe, so that the membrane bag expands to form a weight body to offset the buoyancy and inhibit the pipe piece from floating up.

[0008] Optionally, in step 1, the water-cement ratio of the cement slurry of the cement-water glass double-liquid slurry is 1:0, the modulus of the water glass solution is 3.0, the concentration is 40°Be', and the volume ratio of the cement slurry to the water glass solution is 1:1.

[0009] Preferably, when the prestressed anchor rod is applied, a hole is first drilled in the lower pipe piece to the stable stratum through the lifting hole reserved in the pipe piece, then the anchor rod is inserted, the free end of the anchor rod passes through the lifting hole reserved in the pipe piece, and then the cement-based rapid-setting slurry is poured into the hole, after the slurry is solidified, the designed prestress value is applied through the tensioning equipment, and the anchor nut is used to fasten the anchor rod to the inner surface of the pipe piece; Preferably, the pressure pad is installed between the anchor nut of the prestressed anchor rod and the inner surface of the pipe piece, the pad has a central hole for the prestressed anchor rod to pass through, and the pad has sufficient rigidity and area to ensure that after the prestressed anchor rod is tensioned and locked, the concentrated point load generated by the prestressed anchor rod can be effectively dispersed and converted into a uniform surface load acting on the inner surface of the pipe piece, thereby significantly reducing the local compressive stress and avoiding local compressive damage of the pipe piece concrete; Preferably, in step 3, the cement-water glass double-liquid slurry used to fill the space behind the pipe piece wall is mixed in a ratio of: the cement slurry is composed of cement, bentonite and stabilizer, the water-cement ratio is in the range of 2.0:1 to 3.0:1, the amount of stabilizer is 1.5% of the mass of cement, the water-bentonite ratio is 20:1, the modulus of the water glass solution is 3.0, the concentration is 40°Be', and the volume ratio of the cement slurry to the water glass solution is 12:1 to 20:1, which can be adjusted within this range according to the requirements of stratum conditions, grouting pressure and diffusion distance, etc.

[0010] Preferably, the middle pipe piece is connected with a long distance grouting hose by using the grouting system at the tail of the shield machine, and the cement-water glass double-liquid slurry is injected synchronously with the shield tunneling.

[0011] The beneficial effects of the present application are as follows: The present application provides a layered control method for preventing the floating of a super-large-diameter shield tunnel segment, which constructs a layered collaborative control system of "upper membrane bag pressure application-lower anchor rod uplift resistance-middle grouting reinforcement", and has the following significant advantages: The upper segment applies pressure: expandable membrane bags are arranged outside the upper segment and filled with concrete, and a pressure arch is formed after the membrane bags expand, which applies vertical pressure to offset the floating force acting on the segment, and fills the space after the wall, eliminating the floating space. The lower segment provides uplift resistance: anchor rods are arranged in the lower segment and prestressed, providing strong uplift resistance to offset the floating force acting on the segment, and the supporting pressure pad converts the concentrated point load of the anchor rod acting on the inner surface of the segment into a uniformly distributed surface load, reducing the local compressive stress of the concrete segment and avoiding crushing damage. Middle segment grouting reinforcement: cement-silicate double-liquid slurry is injected into the middle segment area synchronously with the shield tunneling, and the slurry fully fills the voids in the upper, middle and lower full-face walls after hardening, forming a rigid continuous load-bearing structure with the upper membrane bag pressure arch and the lower anchor rod system, greatly improving the overall stiffness of the tunnel and realizing the collaborative working mechanism of the layered anti-floating unit, thereby fundamentally inhibiting the overall floating of the segment. This method innovatively combines layered control and collaborative mechanism, specifically solves the overall floating problem of super-large-diameter shield tunnel segments, breaks through the limitations of traditional single technology in terms of lack of specificity and poor long-term stability, and significantly improves the anti-floating reliability through the "upper membrane bag pressure application-lower anchor rod uplift resistance-middle grouting reinforcement" triple protection. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The processing method of the present application is shown in the figure. DETAILED DESCRIPTION The present application will be further described below in conjunction with the drawings. The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0013] In order to solve the limitations of the prior art in terms of lack of specificity and poor long-term stability in solving the overall floating of large-diameter shield tunnel segments, the present embodiment provides a layered control method for preventing the floating of super-large-diameter shield tunnel segments. This method innovatively constructs a layered control method of "upper membrane bag pressure application-lower anchor rod uplift resistance-middle grouting reinforcement", which forms a pressure arch by arranging membrane bags on the upper segment, sets anchor rods on the lower segment, and uses synchronous grouting in the middle, forming an overall anti-floating system with the upper membrane bag pressure arch and the lower anchor rod, and working collaboratively in layered anti-floating, effectively solving the problem of lack of specific control measures and poor treatment effect in the floating of super-large-diameter shield tunnel segments. The present application improves the construction efficiency while ensuring the safety of the tunnel structure throughout its life cycle through layered collaborative control.

[0014] Example 1 The embodiment proposes a partition processing method for preventing the floating of a super-large-diameter shield tunnel segment, and specifically as follows. After the shield machine cutterhead excavates for a distance to ensure that the construction area is separated from the disturbance influence range of excavation, the segment assembly at the shield tail area is completed, (1) An inflatable membrane bag is arranged outside the upper segment, and cement-water glass quick-setting slurry is injected into the membrane bag through a sleeve to make it expand to form a pressure arch, exert vertical pressure to offset the floating force acting on the segment, and at the same time, the membrane bag expands to fill the wall space in the area where it is located, thereby inhibiting the lifting of the segment; (2) A pre-stressed anchor rod is arranged at the lower segment, the anchor rod provides uplift resistance to offset the floating load acting on the segment, and a pressure pad is provided to convert the concentrated point load of the anchor rod into a uniform surface load on the surface of the segment, thereby improving the stability of the overall structure of the tunnel; (3) After the completion of steps (1) and (2), a grout stopping ring is arranged in the grouting area, and synchronous grouting is performed on the middle segment, and cement-water glass double-liquid slurry is injected from the middle segment. Although the grout injection is started after the completion of steps (1) and (2), it is still injected synchronously with the shield excavation and spreads in a fan shape from the middle to the upper and lower directions, and fully fills the space behind the segment wall. The grout body, the pressure arch formed by the membrane bag at the upper part, and the uplift resistance system provided by the anchor rod at the lower part jointly form a continuous load-bearing structure, which cooperatively inhibits the overall floating of the segment and ensures the long-term stability of the tunnel structure.

[0015] The embodiment provides a layered control method for preventing the floating of a super-large-diameter shield tunnel segment, and constructs a layered collaborative control system of "upper membrane bag pressure application-lower anchor rod uplift resistance-middle grouting reinforcement". The upper segment applies pressure: an inflatable membrane bag is arranged outside the upper segment and is filled with concrete, and after the membrane bag expands, a pressure arch is formed to apply vertical pressure to offset the floating force acting on the segment, and at the same time, the wall space is filled to eliminate the floating space. The lower segment provides uplift resistance: an anchor rod is arranged at the lower segment and is pre-stressed to provide strong uplift resistance to offset the floating force acting on the segment, and a pressure pad is provided to convert the concentrated point load of the anchor rod acting on the inner surface of the segment into a uniform surface load, thereby reducing the local compressive stress of the concrete segment and avoiding crushing damage. The middle segment is grouted and reinforced: cement-water glass double-liquid slurry is injected from the middle segment synchronously with the shield excavation, and the slurry fully fills the space behind the full-face wall of the upper, middle, and lower segments, and after hardening, forms a rigid continuous load-bearing structure with the upper membrane bag pressure arch and the lower anchor rod system, greatly improves the overall stiffness of the tunnel, and realizes the collaborative working mechanism of the layered anti-floating unit, thereby fundamentally inhibiting the overall floating of the segment. This method innovatively integrates layered control and collaborative mechanism, specifically solves the overall floating problem of the super-large-diameter shield tunnel segment, breaks through the limitations of traditional single technology in terms of insufficient pertinence and poor long-term stability, and through the triple protection of "upper membrane bag pressure application-lower anchor rod uplift resistance-middle grouting reinforcement", significantly improves the anti-floating reliability.

[0016] Further, the upper pipe piece membrane bag grouting in step 1 described above adopts a separate grouting system, and the specific membrane bag construction method includes two kinds, which are as follows: The first construction method is: The inlet end of the membrane bag is fixedly connected with the outlet end of the sleeve through a flange and bolts to form a membrane bag grouting device, the sleeve wall is provided with a plurality of grout holes, and the membrane bag body is folded and wrapped around the end of the sleeve. Preferably, when the membrane bag is constructed, the end of the sleeve wrapped with the membrane bag is inserted through the hoisting hole reserved in the pipe piece, and after the end of the sleeve contacts the pipe piece wall, a tee grouting pipe is connected through a flange at the inlet end of the sleeve, cement-water glass double-liquid slurry is pumped, the slurry is uniformly injected and filled into the internal space of the membrane bag through the grout holes in the sleeve wall, the membrane bag is expanded, a certain volume and strength of the weight body is formed to offset the buoyancy and inhibit the pipe piece from floating up, and the pipe piece wall is filled to eliminate the space for the pipe piece to float up; The second construction method is: The membrane bag can be individually pushed to a predetermined position on the outer wall of the pipe piece after being folded through the hoisting hole reserved in the pipe piece, the membrane bag is pre-sewn with a high-strength nylon webbing, the nylon webbing is pulled back to the inside of the pipe piece from the hoisting hole and locked and fixed, the membrane bag is tightly attached to the outer wall of the pipe piece, cement-water glass double-liquid slurry is injected into the membrane bag through the tee grouting pipe to make the membrane bag expand and form a weight body to offset the buoyancy and inhibit the pipe piece from floating up; Preferably, in step 2 described above, when the prestressed anchor rod is constructed, a hole is first drilled in the hoisting hole reserved in the lower pipe piece to the stable stratum, then the anchor rod is inserted, the free end of the anchor rod passes through the hoisting hole reserved in the pipe piece, cement-based quick-setting slurry is then injected into the hole, after the slurry solidifies, a designed prestress value is applied through a tensioning device, and an anchor nut is used to fasten the anchor rod to the inner surface of the pipe piece; Further, the pressure pad is installed between the anchor nut of the prestressed anchor rod and the inner surface of the pipe piece, the pad has a central hole for the prestressed anchor rod to pass through, and the pad has sufficient rigidity and area to ensure that after the prestressed anchor rod is tensioned and locked, the concentrated point load generated by the prestressed anchor rod can be effectively dispersed and converted into a uniform surface load acting on the inner surface of the pipe piece, thereby significantly reducing the local compressive stress and avoiding local compressive damage of the pipe piece concrete; Further, the middle pipe piece is connected with a long distance grouting hose by using a grouting system at the tail of the shield machine, and the cement-silicate double liquid slurry is injected synchronously with the shield tunneling.

[0017] The following will be described in combination with a specific construction method: After the shield machine tunnels to the designed mileage, the pipe pieces are assembled in the safe area behind the shield tail and the anti-floating measures are implemented synchronously; the pipe piece ring is divided into three levels of upper, middle and lower according to the central angle; the upper pipe piece is composed of one 20° top sealing block and two 32° adjacent blocks; the middle pipe piece is symmetrically arranged with four 42° standard blocks; and the lower pipe piece is composed of three 36° standard blocks; the following will be described in combination with the pipe piece design for the specific anti-floating treatment method of the upper pipe piece, the lower pipe piece and the middle pipe piece: Step one: the anti-floating treatment method of the upper pipe piece is as follows: The folded membrane bag is wrapped outside the sleeve, and is fixed as a whole unit with the sleeve through the clamp; the unit is inserted along the hoisting hole reserved in the upper pipe piece, so that the end of the sleeve is embedded into the soil body behind the pipe piece wall; then the double liquid grouting pipe is connected with the inlet end of the sleeve through the flange plate; the cement-silicate double liquid slurry is pumped, so that the membrane bag is expanded to form a pressure arch adhering to the upper pipe piece; The membrane bag is made of flexible material with high strength and corrosion resistance, for example, existing polyethylene composite material; The sleeve is made of Φ80mm*3mm galvanized steel, and the pipe wall is provided with a plum blossom shaped grout outlet hole of Ø10mm@100mm; The cement-silicate double liquid slurry is composed of cement, bentonite and stabilizer, with a water-cement ratio of 2:1, a stabilizer amount of 1.5% of the mass of cement, a water-bentonite ratio of 20:1, a modulus of the water glass solution of 3.0, a concentration of 40°Be', and a volume ratio of the cement slurry to the water glass solution of 15:1; The grouting pressure of the cement-silicate double liquid slurry is 0.5MPa.

[0018] In this step, the inflatable membrane bag is arranged outside the upper pipe piece and the concrete is poured, the membrane bag is expanded to form a pressure arch, vertical pressure is applied to offset the upward force acting on the pipe piece, and the space behind the wall is filled to eliminate the upward space.

[0019] Step two: the treatment method of the lower pipe piece against floating is as follows: A hoisting hole reserved along the lower pipe piece is drilled vertically to the stable stratum, high-pressure water is used to clean the hole, then cement-silicate double slurry is injected, an anchor rod is inserted, pre-stress is applied to the anchor rod by a jack after the slurry solidifies, then a pressure pad is installed, and the pre-stressed anchor rod is fixed to the inner wall of the lower pipe piece by an anchor tool; The anchor rod is made of Φ25 precision rolled threaded steel; The drilling diameter is 50mm; The cement-silicate double slurry is mixed in the following ratio: the cement slurry is composed of cement, bentonite and stabilizer, the water-cement ratio is 2:1, the stabilizer accounts for 1.5% of the mass of the cement, the water-bentonite ratio is 20:1, the modulus of the water glass solution is 3.0, the concentration is 40°Be', and the volume ratio of the cement slurry to the water glass solution is 15:1; The jack applies pre-stress in three stages, which are 150kN, 225kN and 300kN in turn; The pressure pad is 150*150*20mm Q345; In this step, the anchor rod is arranged in the lower pipe piece and pre-stress is applied to provide strong uplift resistance to offset the upward force acting on the pipe piece. The supporting pressure pad converts the concentrated point load of the anchor rod acting on the inner surface of the pipe piece into uniformly distributed surface load, reduces the local compressive stress of the concrete pipe piece, and avoids crushing damage.

[0020] Step three: the treatment method of the lower pipe piece against floating is as follows: Further, after the upper and lower pipe piece anti-floating system is completed, cement-silicate double slurry is injected through the grouting hole of the middle pipe piece; the cement-silicate double slurry is mixed in the following ratio: the cement slurry is composed of cement, bentonite and stabilizer, the water-cement ratio is 2:1, the stabilizer accounts for 1.5% of the mass of the cement, the water-bentonite ratio is 20:1, the modulus of the water glass solution is 3.0, the concentration is 40°Be', and the volume ratio of the cement slurry to the water glass solution is 15:1; The grouting pressure is 0.8MPa, which is diffused at an angle of 25°-30° by a fan-shaped nozzle to penetrate and fill the upper and lower pipe piece wall; The grouting body thus formed, the upper membrane bag pressure arch and the lower anchor rod system jointly constitute a continuous anti-floating bearing structure.

[0021] In this step, cement-silicate double slurry is injected in the middle pipe piece area synchronously with the shield tunneling, the slurry fills the voids in the upper, middle and lower full-section walls, and after hardening, it forms a rigid continuous bearing structure with the upper membrane bag pressure arch and the lower anchor rod system, greatly improves the overall stiffness of the tunnel, realizes the cooperative working mechanism of the layered anti-floating units, and fundamentally suppresses the overall upward floating of the pipe piece.

[0022] The method innovatively fuses layered control and cooperation mechanism, solves the whole floating problem of super-large diameter shield tunnel segment in an targeted manner, breaks through the limitation of traditional single technology in insufficient targeting and poor long-term stability, and significantly improves the anti-floating reliability through the triple protection of "upper membrane bag pressure, lower anchor anti-floating, and middle grouting reinforcement".

[0023] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application. The present application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preventing the floating of an ultra-large diameter shield tunnel segment, characterized in that: Step 1: an inflatable membrane bag is arranged outside the upper segment, and a cement-water glass quick-setting slurry is injected into the membrane bag through a sleeve to make it expand and form a pressure arch; Step 2: a pre-stressed anchor is arranged on the lower segment, and a pressure pad is provided; Step 3: after the completion of steps 1 and 2, the central segment is grouted as the shield tunneling machine advances, and a cement-water glass double-liquid slurry is injected into the central segment, which spreads in a fan shape upward and downward from the central segment to fully fill the space behind the segment wall. The grouting body, together with the membrane bag pressure arch formed on the upper part and the anti-pulling system of the anchor provided on the lower part, forms a continuous load-bearing structure to cooperatively suppress the overall floating of the segment.

2. The method according to claim 1, wherein the method is characterized by, In step 1, the membrane bag grouting of the upper segment uses a separate grouting system.

3. The method of claim 1, wherein the method is characterized by, In step 1, the inlet end of the membrane bag is fixedly connected with the outlet end of the sleeve to form a membrane bag grouting device. The sleeve end wrapped with the membrane bag is folded and wrapped around the sleeve end. A plurality of slurry outlets are formed on the wall of the sleeve inside the membrane bag body.

4. The method according to claim 3, wherein the method is characterized by, When the membrane bag is applied, the sleeve end wrapped with the membrane bag is inserted into the hoisting hole reserved on the upper segment. After the sleeve end contacts the segment wall and the surrounding rock mass, a three-way grouting pipe is connected to the inlet end of the sleeve through a flange plate. A cement-water glass double-liquid slurry is pumped, and the cement-water glass double-liquid slurry is uniformly injected and filled into the internal space of the membrane bag through the slurry outlets on the sleeve wall, which promotes the expansion of the membrane bag and forms a pressure body with a certain volume and strength.

5. The method of claim 1, wherein the method is characterized by: In step 1, the membrane bag is separately folded and pushed to the predetermined position on the outer wall of the segment through the hoisting hole reserved on the segment. The membrane bag is pre-sewn with a nylon webbing, which is pulled back to the inside of the segment through the hoisting hole and locked and fixed to make the membrane bag tightly adhere to the outer wall of the segment. Then, a cement-water glass double-liquid slurry is injected into the membrane bag through a three-way grouting pipe from the grouting hole pre-buried in the membrane bag, which makes it expand and form a pressure body.

6. The method according to claim 3 or 4, wherein the method is characterized by, In step 1, the water-cement ratio of the cement slurry of the cement-water glass double-liquid slurry is 1:0, the modulus of the water glass solution is 3.0, the concentration is 40°Be', and the volume ratio of the cement slurry to the water glass solution is 1:

1.

7. The method for preventing the floating of an ultra-large diameter shield tunnel segment according to claim 1, characterized in that: When the pre-stressed anchor is applied, a hole is drilled in the lower segment to the stable stratum through the hoisting hole reserved on the segment, and then the anchor is inserted. The free end of the anchor passes through the hoisting hole reserved on the segment, and then a cement-based quick-setting slurry is injected into the hole. After the slurry solidifies, a designed pre-stress value is applied through a tensioning device, and an anchor nut is used to fasten the anchor to the inner surface of the segment.

8. The method of claim 1, wherein the method is characterized by, The pressure pad is installed between the anchor nut of the pre-stressed anchor and the inner surface of the segment. The pad has a central hole for the pre-stressed anchor to pass through. The stiffness and area of the pad can ensure that after the pre-stressed anchor is tensioned and locked, the concentrated point load generated by the pre-stressed anchor can be effectively dispersed and converted into a uniformly distributed surface load acting on the inner surface of the segment.

9. The method of claim 1, wherein the method is characterized by, In step 3, the cement slurry of the cement-silicate double slurry is composed of cement, bentonite and stabilizer, the water-cement ratio is in the range of 2.0:1 to 3.0:1, the amount of stabilizer is 1.5% of the mass of cement, the water-bentonite ratio is 20:1, the modulus of the silicate solution is 3.0, the concentration is 40°Be', and the volume ratio of the cement slurry to the silicate solution is 15:

1.

10. The method of claim 1, wherein the method is characterized by: In step 3, the middle pipe segment is connected with long-distance grouting hose by using the grouting system at the tail of the shield machine, and the cement-silicate double slurry is injected synchronously with the shield tunneling.

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