Shield tunneling machine normal-pressure bin opening operation method adopting balance shield mud for sealing and reinforcing

Abstract

The invention discloses a shield tunneling machine normal-pressure bin opening operation method adopting balance shield mud for sealing and reinforcing, and belongs to the field of shield tunneling machine repairing. The method comprises the steps that firstly, pipelines are additionally arranged at a discharge port and an injection port which are communicated with a slurry bin of a shield tunneling machine respectively, then balance shield mud is prepared, and inherent bentonite in the slurry bin is replaced with the balance shield mud through the additionally-arranged pipelines. Then pumping the balance shield into the slurry bin for multiple times through a pipeline additionally arranged at the injection port until the pressure of the slurry bin reaches the ultimate preset pressure, and at the moment, carrying out pressure filtration on the balance shield mud to lose water, and solidifying to form a self-supporting sealing layer; step-by-step pressure reduction is conducted on the muddy water bin in the mode that step-by-step pressure reduction is conducted on the air cushion bin of the shield tunneling machine, and when the pressure of the muddy water bin reaches the preset pressure, step-by-step pressure reduction is stopped; and finally, the muddy water bin is opened in the preset pressure state for needed operation, and the normal-pressure bin opening operation of the shield tunneling machine is completed. According to the method, sudden collapse caused by air pressure change is effectively avoided, the danger in air bin operation is reduced, and the construction cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of tunnel boring machine repair, specifically relating to a method for normal pressure tunnel boring machine opening operation using a shield mud sealing reinforcement. Background Technology

[0002] Tunnel boring machines (TBMs) are primarily used for excavating underground tunnels, especially in urban rail transit, underground pipelines, and tunnel engineering. Due to their strong adaptability and safety, the TBM method is widely used in tunnel construction under various geological conditions, including soft soil, clay, sand, and rock strata. In modern underground tunnel engineering, the complex structure of the TBM is key to its efficient construction. As the core support structure of the equipment, the main body of the TBM uses large steel pipes to construct a temporary tunnel support system, providing safe space for subsequent operations. The cutterhead system at the front end bears the heavy responsibility of breaking through rock and opening the tunnel; densely arranged cutting tools continuously rotate and cut through the soil and rock layers. The propulsion system at the rear of the machine provides the power for forward movement; multiple sets of hydraulic cylinders generate thousands of tons of thrust to drive the TBM to continuously excavate. Simultaneously, the excavation system connected to the rear of the cutterhead, through a screw conveyor and belt conveyor working in tandem, discharges the excavated soil and debris outside the tunnel in real time.

[0003] Tunnel boring machines (TBMs) are commonly used in urban tunnel construction. Under conditions of excessive wear and uneven geological formations, inadequate maintenance of the cutterhead and structural components can damage the TBM cutterhead, preventing normal tunneling cycles. To achieve re-propellant tunneling, a comprehensive repair and correction of the cutterhead is necessary, and all damaged cutterheads must be replaced. The main challenges in cutterhead repair include maintaining the stability and reliability of the tunnel face during maintenance, ensuring the safety and stability of pipelines above the TBM, ensuring the safety of adjacent subway and airport express lines, and simultaneously ensuring airflow, material transport, and safe operation within the confined space in front of the cutterhead.

[0004] However, in numerous practical cases of shield tunneling construction, there have been several instances where the cutterhead and cutting tools were severely damaged and required repair within the tunnel chamber. This is due to the high difficulty and precision requirements of the repair operation, the long operation time, the high risk of working under pressure, the fact that the slurry chamber is filled with bentonite and the extent of damage to the cutterhead and cutting tools cannot be assessed from outside the chamber, and the inability to perform a complete replacement under pressure if necessary. Therefore, there is an urgent need for a method for opening the tunnel chamber at atmospheric pressure to solve these problems. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides a method for atmospheric pressure tunnel boring machine (TBM) opening operation using a shield mud seal reinforcement.

[0006] The technical solution of the present invention is as follows: This invention discloses a method for atmospheric pressure tunnel boring machine (TBM) opening operation using a shield mud seal reinforcement, comprising the following steps: 1) Install pipelines at the discharge port and injection port that are connected to the slurry chamber of the tunnel boring machine; 2) Prepare clay slurry based on unmodified bentonite, and then mix the clay slurry with plasticizer to obtain Hengdun mud; 3) Pump Hengdun mud into the mud-water chamber through the pipeline installed at the injection port. Stop pumping Hengdun mud when the pressure in the mud-water chamber returns to the first preset pressure. Hengdun mud is pumped into the mud-water chamber at a constant pressure. At the same time as Hengdun mud is pumped into the mud-water chamber, the bentonite inherent in the mud-water chamber is discharged through the pipeline installed at the discharge port. 4) The slurry is pumped into the slurry tank in multiple rounds. During each round of pumping, the pressure in the slurry tank reaches the preset pressure for that round. As the number of rounds increases, the preset pressure also increases step by step according to the preset gradient. After the pressure in the slurry tank reaches the preset pressure for each round, it is stabilized for the corresponding preset time. When the final round of pumping is carried out, the pressure in the slurry tank reaches the ultimate preset pressure. Finally, the slurry is dehydrated, solidified, and forms a self-supporting sealing layer. 5) The slurry chamber is depressurized in stages by depressurizing the air cushion chamber of the tunnel boring machine. When the pressure of the slurry chamber reaches the first preset pressure, the depressurization is stopped. 6) Under the first preset pressure state, open the mud chamber to carry out the required operations and complete the normal pressure opening operation of the tunnel boring machine; among which, the required operations include cutterhead maintenance.

[0007] Furthermore, in step 1), the pipes installed at the outlet and the inlet are all pressure-resistant short rigid pipes; A pressure sensor is installed at one end of the pipeline connected to the outlet, and an emergency valve is installed at the other end of the pipeline. A first pressure gauge is also installed on the pipeline near the emergency valve. The pipeline installed at the injection inlet is connected to one end of the injection port and is equipped with an injection port pressure sensor. The other end of the pipeline is equipped with an injection port emergency valve, and a second pressure gauge is installed on the pipeline near the injection port emergency valve. Among them, the pressure resistance rating of the outlet pressure sensor, outlet emergency valve, first pressure gauge, injection port pressure sensor, injection port emergency valve, and second pressure gauge is not less than 25 kg / cm². 2 .

[0008] Furthermore, the inherent structure of the tunnel boring machine includes an outlet valve and an inlet valve; the inlet valve is used to control the opening and closing of the inlet, and the inlet emergency valve is used to control the on / off state of the pipeline installed at the inlet; the outlet valve is used to control the opening and closing of the outlet, and the outlet emergency valve is used to control the on / off state of the pipeline installed at the outlet.

[0009] Further, in step 3), the first preset pressure is 1 Bar; in step 4), the pumped shield mud is pumped in 4 cycles; the preset pressure corresponding to the first cycle is 1.2 Bar, and the preset duration corresponding to this cycle is 1-3 hours; the preset pressure corresponding to the second cycle is 1.4 Bar, and the preset duration corresponding to this cycle is 1-3 hours; the preset pressure corresponding to the third cycle is 1.6 Bar, and the preset duration corresponding to this cycle is 1-3 hours; the preset pressure corresponding to the fourth cycle is 1.8 Bar, and the preset duration corresponding to this cycle is 6-12 hours.

[0010] Furthermore, after completing the normal pressure opening operation of the tunnel boring machine, the outlet valve, inlet valve, inlet emergency valve, and outlet valve are opened simultaneously to pump in the slurry chamber and inject shield mud or water, so that the solidified shield mud becomes liquid shield mud again and is completely discharged from the slurry chamber, thereby releasing the sealing layer of the support seal from the cutterhead and allowing the tunnel boring machine to resume its tunneling state.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention uses the technique of replacing bentonite in the mud-water chamber with balanced mud and then solidifying it by graded pressure. Therefore, it overcomes the problems of sudden collapse caused by sudden changes in air pressure when opening the chamber under air pressure and the high risk of pressurized operation in the prior art. Thus, it achieves the technical effect of safe opening of the chamber under normal pressure and significantly reduced operation risk.

[0012] 2) This invention uses the technique of pressure filtration of shield mud to form a self-supporting sealing layer, thus overcoming the problem that the mud chamber is filled with bentonite and the degree of damage to the cutterhead and cutters cannot be judged from outside the chamber in the existing technology; the solidified shield mud of this invention can also be liquefied and discharged again, so that the shield can quickly resume tunneling after operation without affecting the construction efficiency.

[0013] 3) This invention uses the technical means of adding pressure-resistant pipelines and graded pressure control, thus overcoming the problems of inaccurate pressure monitoring and uncontrollable pressure reduction process in the prior art, thereby achieving the technical effects of accurate pressure verification, stable and controllable pressure reduction, and standardized operation process.

[0014] 4) This invention uses atmospheric pressure opening to replace pressurized operation, thus overcoming the difficulties of maintenance operation, high precision requirements and long operation time in the prior art, thereby achieving the technical effects of simplifying construction procedures, reducing construction costs and improving operation efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of the method for operating the atmospheric pressure air chamber of a tunnel boring machine using a shield mud sealing reinforcement according to the present invention. Figure 2 This is a schematic diagram of synchronous grouting in the shield machine atmospheric pressure chamber operation method using the shield mud sealing reinforcement of the present invention; Figure 3 This is a schematic diagram showing the locations of the injection port and discharge port of the shield machine atmospheric pressure air chamber operation method using the shield mud sealing reinforcement of the present invention. Figure 4 This is a schematic diagram of a tunnel boring machine (TBM) using the atmospheric pressure air chamber operation method of the present invention, which employs a shield mud sealing reinforcement.

[0016] Explanation of reference numerals in the attached diagram: 1. Discharge port; 2. Injection port; 3. First pressure sensor; 4. Air cushion chamber pressure baffle; 5. Pressure-resistant short rigid pipe; 6. Synchronous grouting box; 7. Top exhaust valve; 8. Cutterhead; 9. Mud and water chamber; 10. Air cushion chamber; 11. Discharge port pressure sensor; 12. Injection port pressure sensor; 13. Discharge port valve; 14. Mud gate; 15. Injection port valve; 16. Feeder; 17. Temporary waste slurry bucket; 18. Discharge port emergency valve; 19. Injection port emergency valve; 20. Pressure gauge; 21. Synchronous grouting pipe. Detailed Implementation

[0017] The present invention will be further described and illustrated below with reference to specific embodiments. The embodiments described are merely examples of the content of this disclosure and do not limit the scope of the invention. The technical features of each embodiment in the present invention can be combined accordingly, provided that there is no mutual conflict.

[0018] This embodiment describes the method for normal pressure tunnel boring machine (TBM) opening operation using a shield mud sealing reinforcement method, based on a specific construction case of an urban expressway. For example... Figure 1 As shown, the method for opening the tunnel boring machine at atmospheric pressure includes the following steps: Step 1): Preparation of Hengdun mud and installation of Hengdun mud injection pipeline like Figure 4 As shown, it was confirmed with the tunnel boring machine (TBM) manufacturer that the pipes at outlet 1 and inlet 2 of the TBM are indeed connected to the slurry chamber 9, and that the valves connecting the pipes at outlet 1 and inlet 2 to the air cushion chamber 10 are closed. Specifically, the pipes at outlet 1 and inlet 2 pass through the pressure baffle 4 of the air cushion chamber and are directly connected to the interior of the slurry chamber 9. The outer walls of the pipes are sealed to the pressure baffle and do not communicate with the air cavity of the air cushion chamber 10. Figure 3 The air cushion chamber pressure partition 4 is a pressure-bearing separation structure between the mud-water chamber 9 and the air cushion chamber 10 of the tunnel boring machine. It is used to completely separate the mud-water chamber 9 and the air cushion chamber 10 in space, forming two independent pressure-bearing cavities. Figure 3 The first pressure sensor 3 is installed at the top of the mud and water tank 9 and near the pressure baffle 4 of the air cushion tank, and is used to monitor the pressure value at the top of the mud and water tank 9 in real time. Figure 3 The top vent valve 7 is located at the highest point of the mud and water chamber 9 and is used to vent residual air inside the chamber; this valve is not connected to the air cushion chamber. Figure 3All structures shown are inherent to the tunnel boring machine and are not newly added to achieve the tunnel boring machine atmospheric pressure opening operation method of the present invention.

[0019] After confirming that everything is correct, connect the outlet 1 and the inlet 2 using a pressure-resistant short rigid pipe 5. Install an outlet emergency valve 18, an outlet pressure sensor 11, and a pressure gauge 20 on the pressure-resistant short rigid pipe 5 connected to outlet 1; and install an inlet emergency valve 19, an inlet pressure sensor 12, and a pressure gauge 20 on the pressure-resistant short rigid pipe 5 connected to inlet 2. The pressure resistance rating of the outlet emergency valve 18, inlet emergency valve 19, outlet pressure sensor 11, inlet pressure sensor 12, and pressure gauge 20 must all be no less than 25 kg / cm². 2 The inlet pressure sensor 12 is installed at the connection end between the pressure-resistant short rigid pipe 5 and the inlet 2. The pressure gauge 20 is installed at the other end of the pressure-resistant short rigid pipe 5. The inlet emergency valve 19, which is attached to the pressure-resistant short rigid pipe 5 connected to the inlet 2, is installed on the pressure-resistant short rigid pipe 5 near the inlet pressure sensor 12. The outlet pressure sensor 11 is installed at the connection end between the pressure-resistant short rigid pipe 5 and the outlet 1. The pressure gauge 20, which is attached to the pressure-resistant short rigid pipe 5 connected to the outlet 1, is installed at the other end of the pressure-resistant short rigid pipe 5. The outlet emergency valve 18 is installed on the pressure-resistant short rigid pipe 5 near the outlet pressure sensor 11.

[0020] Meanwhile, the pressure of the slurry chamber 9 and the air cushion chamber 10 is sensed and verified by combining the original pressure monitoring system of the tunnel boring machine (TBM) with an external pressure monitoring device. Specifically, the pressure of the slurry chamber 9 is monitored in real time by the outlet pressure sensor 11, the inlet pressure sensor 12, and the pressure gauge 22 installed on the outlet 1 and inlet 2 pipelines, and verified in conjunction with the original chamber pressure display data of the TBM. The pressure of the air cushion chamber 10 is monitored in real time by the air cushion chamber pressure sensor and control system built into the TBM. During construction, the value displayed by the TBM's main control system is used as the primary criterion, with the readings of the external pressure sensors and pressure gauges used as auxiliary verification criteria, thereby improving the accuracy and reliability of chamber pressure monitoring. Specifically, the inlet pressure sensor 12 is used to monitor the pressure of inlet 2 in real time and provide feedback to the control system to ensure pressure stability and adjust injection conditions; the pressure gauge 22 provides data for manual reading of the inlet pressure for operator monitoring; the purpose of pressure observation is to ensure pressure stability during the injection process and prevent construction problems caused by excessively high or low injection pressure. If the values ​​displayed on the main control system of the tunnel boring machine are inconsistent with the readings of the external monitoring device, the operation should be suspended, and the status of the sensors, pressure gauges and pipeline connections should be checked. The fault should be eliminated and the system calibrated before construction can be resumed.

[0021] Figure 4Both the outlet valve 13 and the inlet valve 15 are inherent structures of the tunnel boring machine. During the injection process, the outlet valve 13 is used to control the discharge of mud, and by adjusting its opening and closing, it ensures the stability of the pressure in the mud chamber 9, avoiding excessively high or low pressure that could affect the injection effect. At the same time, the inlet valve 15 is used to control the injection flow rate of mud (in this invention, the injected mud is shield mud), and by adjusting the inlet pressure, it ensures the fluidity and stability of the mud during the injection process.

[0022] After completion, clearly mark all newly installed pipelines. Ensure all pipelines are functioning correctly and that a certain amount of bentonite is provided in the tunnel boring machine's synchronous grouting tank 6. Mark any unobstructed pipelines; for blocked pipelines, flush them with a high-pressure water hose. Ensure multiple access points are available whenever possible.

[0023] Clay slurry is used as liquid A, and a plasticizer is used as liquid B. The plasticizer should possess the following physical properties: it is a homogeneous liquid at room temperature, without significant stratification or sedimentation; it has good water solubility or dispersibility, enabling it to mix uniformly with the clay slurry; it has low viscosity and good fluidity, facilitating delivery and injection via pipelines and constant-pressure pumps; and it is physically stable within the storage and construction temperature range, without significant thickening, clumping, or instability. Preferably, the density of the plasticizer at 25°C is 1.00-1.20 g / cm³. 3 The dynamic viscosity is 10-300 mPa·s.

[0024] Liquid A and liquid B are mixed to obtain Hengdun slurry. Based on the small-scale samples taken on site, unmodified bentonite is used as material A, with a ratio of material A to water of 1:1.15-3 and a ratio of liquid A to liquid B of 12.5-20:1 (both by mass). After mixing, the mixture is thoroughly stirred to ensure uniformity, and the stirring time is 15-20 minutes. The slump is 14-16, and the resulting slurry meets the requirements for bentonite replacement in the slurry tank of this project. Unmodified bentonite is a clay mineral with montmorillonite as its main component. It has a monoclinic crystal structure, and its montmorillonite content is generally greater than 65%, with a relative density of 2.4-2.8 and a melting point of 1330-1430°C.

[0025] Liquid A, used to form the shield mud, is mixed at the mortar station and injected into the synchronous grouting tank 6 via a mortar truck and ground pump. The inner wall of the synchronous grouting tank 6 has a length L1 of 4.8m and a width L2 of 1.6m. Diluting liquid A with water is strictly prohibited during transportation. After liquid A is delivered to the synchronous grouting tank 6, the actual height h1 of the liquid level in the tank is measured. The actual volume V1 of the grout in the synchronous grouting tank 6 is calculated using L1×L2×h1. The actual specific gravity γ1 of liquid A at this time is measured using a hydrometer (it should be between 1.42 and 1.44). The actual weight m of liquid A in the synchronous grouting tank 6 is obtained by multiplying V1 by γ1. Liquid B is added according to the ratio of liquid A and liquid B used in the production test, and the mixture is then used to obtain the shield mud.

[0026] During the initial pipeline test run, the pressure-resistant short rigid pipe 5 at the front end is not connected to the outlet 1 or the injection port 2. This test run purges the air from the pressure-resistant short rigid pipe 5, and the pressure at the injection port 2 is monitored using the injection port pressure sensor 12 to ensure stable pressure during the injection process and prevent construction problems caused by excessively high or low injection pressure. After the air in the pipeline has been purged, connect the outlet 1 and injection port 2 to their respective pressure-resistant short rigid pipes 5.

[0027] Step 2): Slag and soil replacement The bentonite from the synchronous grouting box 6 is injected into the slurry chamber 9 at constant pressure through the injection port 2 and the synchronous grouting pipe 21. Simultaneously, the outlet valve 13 and the emergency outlet valve 18 are opened to utilize the pressure built up within the slurry chamber 9 to discharge the bentonite. The discharged bentonite is discharged through the pipe at the injection port 2 into a temporary waste slurry bucket 17 placed at the feeder 16. During the injection of the bentonite, the injection pressure is monitored in real time by the injection port pressure sensor 12, and the injection flow rate of the bentonite is adjusted according to pressure changes to ensure constant pressure injection of the bentonite into the slurry chamber 9. When the pressure in the slurry chamber 9 returns to 1 Bar (the initial reference pressure of the slurry chamber 9 before the shield tunneling machine stops and before the bentonite is injected is 1 Bar; the pressure in the slurry chamber 9 will briefly increase during the injection process), the outlet valve 13 and the emergency outlet valve 18 are closed. This signifies that all the bentonite has been discharged, and the entire replacement process is complete. The method for handling the replaced bentonite is as follows: First, the discharged bentonite slurry is diluted on site. Then, the diluted bentonite slurry is transported to the waste slurry tank in the G1 chassis for temporary storage through a pumping system. The waste slurry tank is then pumped to the tunnel starting shaft and finally discharged into the slurry conditioning pool of the surface mud station for unified treatment and recycling.

[0028] Step 3): Staged pressurization First-stage pressurization: Open the injection port valve 15 and the emergency injection port valve 19 of the mud-water tank 9, and inject the shield mud into the mud-water tank 9 through the pipeline of injection port 2. At the same time, the pressure inside the mud-water tank 9 is monitored by the first pressure sensor 3. When the pressure at the top of the mud-water tank 9 rises to 1.2 Bar, the injection of shield mud is stopped, and then the pressure is stabilized for 2 hours. If the pressure drops by more than 0.05 Bar during this period, shield mud is injected again until the pressure at the top of the mud-water tank 9 rises to 1.2 Bar.

[0029] Secondary pressurization: Continue to inject Hengdun mud into the mud-water chamber 9. When the pressure in the mud-water chamber 9 rises to 1.4 Bar, stop injecting Hengdun mud and then maintain the pressure for 2 hours. If the pressure drops during this period, inject Hengdun mud again until the pressure at the top of the mud-water chamber 9 rises to 1.4 Bar.

[0030] Third-stage pressurization: Continue injecting shield mud into the mud-water chamber 9. When the pressure inside the mud-water chamber 9 reaches 1.6 Bar, stop injecting the shield mud and then maintain the pressure for 2 hours. If the pressure drops during this period, replenish the shield mud until the pressure at the top of the mud-water chamber 9 rises to 1.6 Bar. During this stage, the cutter head 8 can be intermittently micro-adjusted at a speed of 0.1-0.2 rpm to facilitate the uniform distribution of the shield mud.

[0031] Fourth-stage pressurization (final pressure): Hengdun mud is injected again into mud-water chamber 9. When the pressure inside chamber 9 reaches 1.8 Bar (0.8 Bar higher than the target atmospheric pressure), the injection of Hengdun mud is stopped. This final pressure is maintained for at least 6-12 hours. This prolonged pressure stabilization process is crucial to ensure that the Hengdun mud fully dehydrates and completely solidifies to achieve the design strength (≥0.8 MPa).

[0032] Step 4) Pressure Reduction and Atmospheric Pressure Verification After the slurry in front of the tunnel face dehydrates and solidifies to form a self-pressure-bearing sealing layer, pressure reduction and atmospheric pressure verification begin. The pressure of the slurry chamber 9 is monitored in real time by the outlet pressure sensor 11, the inlet pressure sensor 12, and the pressure gauge 20, and verified in conjunction with the original chamber pressure display system of the tunnel boring machine (TBM). The pressure of the air cushion chamber 10 is monitored in real time by the original air cushion chamber pressure sensor and the air pressure control system of the TBM. The pressure reduction process is implemented through the air pressure regulation function of the TBM, specifically by gradually reducing the air supply to the air cushion chamber 10 and releasing the compressed air in the air cushion chamber 10 in stages through the original exhaust valve and related control valve group of the TBM, so that the pressure of the air cushion chamber 10 gradually decreases. As the pressure of the air cushion chamber 10 decreases, the pressure in the slurry chamber 9 also decreases accordingly. If necessary, the opening and closing control of the slurry gate 14 and related slurry pipelines can be used to ensure a smooth transition of pressure in the chamber, avoiding disturbance to the tunnel face or instability of the sealing layer caused by instantaneous pressure relief. The pressure reduction was carried out in stages, with each stage reducing the pressure by 0.1–0.2 Bar. After each stage of pressure reduction, the pressure was stabilized and observed for 2–4 hours, and the pressure changes in the mud-water chamber 9 and the air cushion chamber 10 were continuously recorded. By comparing the pressure data at each measuring point, it can be determined whether the pressure inside the chamber remained stable after the sealing layer was formed, and whether there was any abnormal pressure loss.

[0033] The reason for gradually reducing the pressure in the air cushion chamber 10 and the slurry chamber 9 is to verify whether the sealing layer formed after the shield slurry dehydrates and solidifies can independently withstand external groundwater pressure and formation pressure without relying on the air pressure balance inside the shield machine chamber. Only when the sealing layer remains stable after the chamber pressure drops to atmospheric pressure can it be said that the sealing layer has the ability to replace the original air pressure balance function, thereby changing the subsequent personnel entering the chamber from a pressurized environment to an atmospheric pressure environment, reducing the risk of opening the chamber under pressure, and improving the safety and convenience of maintenance and cutterhead replacement operations.

[0034] During the pressure stabilization observation process at each level, the seepage volume should also be monitored through the slurry discharge pipeline. The seepage volume can be measured using a transparent measuring container, graduated collection bucket, or online flow meter connected to the slurry discharge pipeline. The volume of liquid discharged within a predetermined time period is recorded and converted into a seepage flow rate per unit area based on the corresponding area of ​​the sealing layer. If the volume of liquid discharged during the pressure stabilization period is small and gradually decreases, it indicates that the water-proofing performance of the sealing layer is gradually stabilizing. The "water" monitored in the slurry discharge pipeline mainly originates from two sources: first, groundwater in the strata outside the working face seeps into the working face through local pores, micro-cracks, or weak points that are not yet completely sealed, under the influence of pressure differential; second, a small amount of free water or filtrate lost during the pressure consolidation and filtration process of the shield mud. The discharge of these two types of liquid through the slurry discharge pipeline serves as an important basis for evaluating the integrity and seepage prevention performance of the sealing layer.

[0035] During the 2-4 hour pressure stabilization phase, the pressure drop rate of mud-water silo 9 is small, no abnormal pressure loss occurs, and the seepage flow rate remains below 0.1 L / m³. 2 At h, the next stage of pressure reduction can continue. Repeat the above process of "graded pressure reduction - pressure stabilization observation - monitoring pressure and seepage flow" until the pressure inside the mud-water chamber 9 drops to atmospheric pressure (1 Bar). Continue to stabilize the pressure at atmospheric pressure for no less than 12 hours; if the pressure inside the chamber remains stable during this period and the seepage flow always meets the requirements, it is determined that the sealing layer formed by the solidification of the shield mud is capable of independently withstanding the external water and soil pressure, and atmospheric pressure opening operation can be carried out.

[0036] Step 5): Opening the warehouse under normal pressure Before opening the slurry chamber for construction, the engineering department is responsible for conducting a comprehensive inspection to ensure that the work site meets safety standards. When entering the slurry chamber 9 for cutter replacement, special attention must be paid to the ventilation and drainage systems within the chamber to ensure a safe working environment. Before commencing operations, a gas test must be conducted to ensure that the gas levels in the chamber are within acceptable limits, that no harmful gases have accumulated, and that safety standards are met before the chamber can be opened for cutter replacement.

[0037] Step 6): Cutterhead excavation, shield mud liquefaction, and seal release. After the atmospheric pressure opening operation is completed, the shield mud in slurry chamber 9 has gradually solidified due to pressure and time, forming a sealing layer that ensures ground stability during tunnel boring machine (TBM) operation. To prepare for restarting tunneling, the following operations are required: 1) Discharge of solidified shield mud: After the cutterhead completes tunneling, the solidified shield mud in the mud chamber 9 needs to be discharged. To do this, the discharge outlet valve 13 is opened, and the pressure inside the mud chamber 9 is used to discharge the solidified shield mud into the temporary waste slurry bucket 17 placed at the feeder 16. The solidified shield mud is successfully discharged through the discharge pipe, ensuring that it will not affect the next stage of tunneling.

[0038] 2) Liquefaction of Hengdun Slurry: To discharge solidified Hengdun slurry, it must first be restored to its fluidity. This process is called Hengdun slurry liquefaction. Liquefaction involves injecting an appropriate amount of liquid Hengdun slurry or water into the slurry tank, causing the solidified slurry to revert to a fluid state. The liquefied slurry can be discharged smoothly without clogging the discharge pipes. During liquefaction, the injection port pressure is monitored in real time to ensure that the liquefied slurry is discharged within an appropriate pressure range.

[0039] 3) Seal Release: After the liquefaction process is complete and the solidified mud is discharged, the sealing layer in the mud chamber is released. At this time, the outlet valve 13 is closed, and the pressure in the mud chamber is ensured to return to atmospheric pressure (1 Bar). Once the pressure has returned to atmospheric pressure and the solidified mud has been discharged, the working environment in the mud chamber is confirmed to meet the requirements before subsequent cutterhead replacement operations or continued tunneling can proceed.

[0040] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for atmospheric pressure tunnel boring machine (TBM) opening operation using a shield-sealing reinforcement system, characterized in that, Includes the following steps: 1) Install pipelines at the discharge port and injection port that are connected to the slurry chamber of the tunnel boring machine; 2) Prepare clay slurry based on unmodified bentonite, and then mix the clay slurry with plasticizer to obtain Hengdun mud; 3) Pump Hengdun mud into the mud-water chamber through the pipeline installed at the injection port. Stop pumping Hengdun mud when the pressure in the mud-water chamber returns to the first preset pressure. Hengdun mud is pumped into the mud-water chamber at a constant pressure. At the same time as Hengdun mud is pumped into the mud-water chamber, the bentonite inherent in the mud-water chamber is discharged through the pipeline installed at the discharge port. 4) The slurry is pumped into the slurry tank in multiple rounds. During each round of pumping, the pressure in the slurry tank reaches the preset pressure for that round. As the number of rounds increases, the preset pressure also increases step by step according to the preset gradient. After the pressure in the slurry tank reaches the preset pressure for each round, it is stabilized for the corresponding preset time. When the final round of pumping is carried out, the pressure in the slurry tank reaches the ultimate preset pressure. Finally, the slurry is dehydrated, solidified, and forms a self-supporting sealing layer. 5) The slurry chamber is depressurized in stages by depressurizing the air cushion chamber of the tunnel boring machine. When the pressure of the slurry chamber reaches the first preset pressure, the depressurization is stopped. 6) Under the first preset pressure state, open the mud chamber to carry out the required operations and complete the normal pressure opening operation of the tunnel boring machine.

2. The method for opening the tunnel boring machine at atmospheric pressure according to claim 1, characterized in that, In step 1), the pipes installed at the outlet and inlet are all pressure-resistant short rigid pipes; A pressure sensor is installed at one end of the pipeline connected to the outlet, and a first pressure gauge is installed at the other end of the pipeline. An emergency valve for the outlet is also installed on the pipeline near the pressure sensor. The pipeline installed at the injection inlet is connected to one end of the injection port and is equipped with an injection port pressure sensor. The other end of the pipeline is equipped with a second pressure gauge, and an injection port emergency valve is installed on the pipeline near the injection port pressure sensor. Among them, the pressure resistance rating of the outlet pressure sensor, outlet emergency valve, first pressure gauge, injection port pressure sensor, injection port emergency valve, and second pressure gauge is not less than 25 kg / cm². 2 .

3. The method for opening the tunnel boring machine at atmospheric pressure according to claim 2, characterized in that, The outlet pressure sensor, the first pressure gauge, the inlet pressure sensor, and the second pressure gauge are all used to reflect the pressure of the slurry chamber and serve as an auxiliary verification basis for the pressure of the slurry chamber; the actual pressure value of the slurry chamber is the detection value of the first pressure sensor inherent to the tunnel boring machine.

4. The method for opening the tunnel boring machine at atmospheric pressure according to claim 2, characterized in that, The inherent structure of the tunnel boring machine includes an outlet valve and an inlet valve; the inlet valve is used to control the opening and closing of the inlet, and the inlet emergency valve is used to control the on / off state of the pipeline installed at the inlet; the outlet valve is used to control the opening and closing of the outlet, and the outlet emergency valve is used to control the on / off state of the pipeline installed at the outlet.

5. The method for opening the tunnel boring machine at atmospheric pressure according to claim 1, characterized in that, In step 2), unmodified bentonite and water are mixed at a mass ratio of 1:1.15-3 to obtain clay slurry. The clay slurry is then mixed with plasticizer at a mass ratio of 12.5-20:

1. After mixing, the mixture is stirred for 15-20 minutes to obtain Hengdun mud, which has a slump of 14-16. The unmodified bentonite is a clay mineral with montmorillonite as its main component, containing more than 65% montmorillonite, with a relative density of 2.4-2.8 and a melting point of 1330-1430°C; the plasticizer has a density of 1.00-1.20 g / cm³ at 25°C. 3 The dynamic viscosity is 10-300 mPa·s.

6. The method for opening the tunnel boring machine at atmospheric pressure according to claim 4, characterized in that, When injecting the shield mud in step 3), simultaneously open the outlet valve, the injection port valve, the injection port emergency valve, and the outlet valve; When injecting the shield mud in step 4), open the injection port valve and the injection port emergency valve, and close the discharge port valve and the discharge port valve.

7. The method for opening the tunnel boring machine at atmospheric pressure according to claim 1, characterized in that, The first preset pressure in step 3) is 1 Bar; the pumping of the shield mud in step 4) is 4 times; The preset pressure for the first round is 1.2 Bar, and the preset duration for this round is 1-3 hours. The preset pressure for the second round is 1.4 Bar, and the preset duration for this round is 1-3 hours. The preset pressure for the third round is 1.6 Bar, and the preset duration for this round is 1-3 hours. The preset pressure for the fourth round is 1.8 Bar, and the preset duration for this round is 6-12 hours.

8. The method for opening the tunnel boring machine at atmospheric pressure according to claim 7, characterized in that, During the third execution of step 4), the cutterhead of the tunnel boring machine is intermittently rotated at a speed of 0.1-0.2 rpm while the shield mud is being pumped in.

9. The method for opening the tunnel boring machine at atmospheric pressure according to claim 4, characterized in that, In step 5), during the staged pressure reduction, open the outlet valve and the outlet valve, close the inlet valve and the inlet emergency valve, and collect the liquid discharged from the mud and water tank at the pipeline installed at the outlet. Each pressure reduction stage involves a decrease of 0.1-0.2 Bar. After each stage of pressure reduction, except for the final stage, the pressure is stabilized for 2-4 hours. During the stabilization process, if no abnormal pressure loss occurs in the slurry chamber and the seepage rate is below 0.1 L / m³, the pressure should be maintained. 2 When h is reached, the pressure reduction stage is considered complete, and the next stage of pressure reduction continues; the pressure is stabilized for no less than 12 hours after the last stage of pressure reduction is completed.

10. The method for opening the tunnel boring machine at atmospheric pressure according to claim 4, characterized in that, After completing the normal pressure opening operation of the tunnel boring machine, the outlet valve, inlet valve, inlet emergency valve, and outlet valve are opened simultaneously to pump in the slurry chamber and inject shield mud or water, so that the solidified shield mud becomes liquid shield mud again and is completely discharged from the slurry chamber. This releases the sealing layer of the support seal from the cutterhead and allows the tunnel boring machine to resume its tunneling state.

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