A shield machine tool changing system with pressure and its construction method

Abstract

The present invention discloses a shield tool changing system under pressure and a construction method thereof, which is suitable for non-saturated tool changing operation under pressure, and includes a mixed gas distribution device, an oronasal mask respirator, a decompression oxygen inhalation device and a man cabin. The mixed gas distribution device includes an automatic distribution component, a manual distribution component and a mixed gas storage tank. The automatic distribution component or the manual distribution component mixes and proportions compressed air, oxygen and helium, and stores the proportioned helium-nitrogen-oxygen ternary mixed gas in the mixed gas storage tank. The man cabin is used for pressurization and decompression before and after the operator works under pressure. The oronasal mask respirator and the decompression oxygen inhalation device are arranged in the cabin. The oronasal mask respirator is connected to the mixed gas storage tank through a high-pressure hose, and the decompression oxygen inhalation device is connected to the oxygen supply device through an air supply pipeline. In the present invention, the operator directly enters the man cabin, breathes the helium-nitrogen-oxygen ternary mixed gas by wearing the oronasal mask respirator, quickly adapts to the high-pressure working environment, and safely enters the mud and water tank to carry out tool changing operation.

Description

Technical Field

[0001] The present invention relates to the technical field of shield construction, and in particular to a shield pressure cutter changing system and a construction method thereof. Background Art

[0002] With the rapid development of large-scale infrastructure such as urban rail transit and river-crossing and sea-crossing tunnels, large-diameter slurry shield machines are increasingly being used for tunneling in deep and complex strata. During the tunneling process, the shield machine inevitably needs to perform tool changes or obstacle clearance operations under high pressure at the face. These operations are collectively referred to as pressurized operations. According to the "Technical Requirements for Air Diving Decompression" GB / T12521-2008, pressurized operations in conventional compressed air environments cannot be performed when the pressure exceeds 6 bar. Practice has also shown that when the operating pressure exceeds 5 bar, the duration of air pressurized operations is limited to approximately 35 minutes, significantly reducing operational efficiency and significantly increasing the potential risk of decompression sickness and oxygen poisoning during operations. Faced with the current trend of increasing shield construction depths, traditional air pressurized methods are unable to meet the long-term, high-intensity operational requirements of deep tunnels.

[0003] In order to overcome the limitations of conventional air pressure methods in high-pressure environments, current engineering practices have begun to try to adopt saturated pressure operation methods, that is, using helium-oxygen mixed gas for deep diving operations to extend the operation time and ensure personnel safety. For example, the saturated pressure method was used to replace tools in the Nanjing Weisan Road Project. For example, CN112943270A discloses a construction method for large-diameter shield pressure tool replacement under ultra-high water pressure conditions. It uses a helium-oxygen saturated pressure method, which requires the provision of a living cabin and a shuttle cabin. The operating personnel need to gradually pressurize the living cabin to adapt to the high-pressure environment, and then transfer to the soil cabin through the shuttle cabin to perform tool changing operations. Helium-oxygen mixed gas is also required to replace the air in the human cabin and mud and water cabin of the shield machine.

[0004] However, this method has significant drawbacks: First, the operation preparation cycle is long, with initial equipment installation and commissioning typically taking no less than 15 days. Second, operational efficiency is low, with effective daily operating time approximately 12 hours, and continuous operation cycles are limited, requiring mandatory rest periods exceeding 20 days. Furthermore, the saturated pressure operation system is complex, requires strict staffing, and has limited emergency response capabilities, making it unsuitable for rapid tool changes. This is particularly true in large-diameter shield tunneling operations, where the large number of tools and high frequency of tool changes often make it difficult to complete within a single cycle, resulting in prolonged shield machine downtime and significantly increased construction risks and costs. Furthermore, the heavy diving gear restricts the operator's operational freedom, leading to overall low efficiency. While helium-oxygen saturation diving in deep working environments can meet high-pressure operation requirements, the high helium consumption and complex equipment significantly increase both the economic cost and operational difficulty. Therefore, a new technology for shield pressure operation that is more efficient, flexible, and adaptable to high-pressure environments is urgently needed. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a shield pressurized tool changing system and its construction method, which eliminates the traditional living cabin and shuttle cabin structure. The operating personnel can directly enter the human cabin, breathe a helium-nitrogen-oxygen ternary gas by wearing an oral and nasal mask respirator, quickly adapt to the high-pressure working environment, and safely enter the mud and water tank to carry out tool changing operations. This solves the problems of traditional air pressurized operations that cannot adapt to high-pressure environments, short operating time, low efficiency, and long saturated pressurized operation cycles, complex preparations, high costs, and lack of rapid response capabilities.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A shield tool changing system under pressure is suitable for non-saturated tool changing operations under pressure. The shield tool changing system under pressure includes a mixed gas distribution device, an oronasal mask respirator, a decompression oxygen inhalation device and a man cabin. The mixed gas distribution device includes an automatic gas distribution component, a manual gas distribution component and a mixed gas storage tank. The automatic gas distribution component or the manual gas distribution component mixes and proportions compressed air, oxygen and helium, and stores the proportioned helium-nitrogen-oxygen ternary mixed gas in the mixed gas storage tank. The man cabin is used for pressurization and decompression before and after the workers work under pressure. An oronasal mask respirator and a decompression oxygen inhalation device are set in the cabin. The oronasal mask respirator is connected to the mixed gas storage tank through a high-pressure hose, and is used to supply the ternary mixed gas to the workers during the operation. The decompression oxygen inhalation device is connected to the oxygen supply device through an air supply pipeline, and is used to provide the workers with an oxygen inhalation channel during the decompression process to accelerate the desaturation process.

[0008] Preferably, in the mixed gas distribution device, air, oxygen and helium pass through the pressure-stabilizing valve, transmitter, manual valve, filter, flow controller and check valve of the automatic gas distribution assembly, enter the No. 1 mixing row, adjust the pressure through the back pressure valve, flow into the No. 2 mixing row through two gas supply pipes, and finally reach the mixed gas storage tank. The No. 2 mixing row is connected to the manual gas distribution assembly.

[0009] Preferably, the man cabin is connected to a pressurizing device of the shield machine, and the pressurizing device adjusts the pressure in the cabin by filling compressed air into the man cabin.

[0010] Preferably, an intercom, a handwriting board and an alarm device are provided in the man cabin. The intercom and handwriting board are used for the operator to communicate with the control room. The alarm device is used to identify the working status of the operator and upload the working status information to the control room.

[0011] Preferably, the decompression oxygen inhalation device adopts a thin film head cover, including a transparent sealing cover body, which is used to completely seal the head and neck of the operator and has mechanical automatic oxygen supply and mechanical automatic oxygen exhaust functions.

[0012] Preferably, in the ternary mixed gas, the partial pressure PO of oxygen is 1.4-2.0 ATA, the partial pressure PN of nitrogen is ≤4 ATA, and the rest is helium.

[0013] On the other hand, the present invention discloses a construction method based on the above-mentioned shield belt pressure tool changing system, comprising the following steps:

[0014] S1: The diving doctor will conduct a special physical examination on the knife change operator, confirming that the pulse, blood oxygen saturation and physical condition are normal before preparing to enter the cabin;

[0015] S2: After the working personnel leave the cabin, the tool change personnel of this shift will check and clean the breathing air system, and the safety officer will check whether they are carrying flammable and explosive items;

[0016] S3, the tool change operator enters the cabin, checks the tools and communication system, and then the operator pressurizes the cabin;

[0017] S4: When the pressure in the cabin reaches 2.4 bar, the operator begins to wear a mouth-nose respirator to breathe the ternary mixed gas. When the pressure reaches 3.0 bar, the operator stops pressurizing and confirms that the mouth-nose respirator is working properly through voice or handwritten text. After confirming that there are no abnormalities, the operator stops pressurizing until the pressure in the cabin is consistent with that in the excavation chamber.

[0018] S5: The tool change operator opens the door between the man cabin and the air cushion chamber. Three operators enter the air cushion chamber and then open the door between the air cushion chamber and the mud and water chamber to start the operation.

[0019] During S6, one person is responsible for observation and delivery in the air cushion chamber, and two people enter the mud and water chamber to perform the tool change operation;

[0020] S7: 10 minutes before the end of the operation cycle, the operator notifies the operators to stop working, organizes the tools, closes the connecting door between the mud and water tank and the air cushion tank, and the operators return to the cabin;

[0021] S8: After all the operators have entered the cabin and closed the hatch, the operator starts the decompression procedure and the operators continue to wear oral and nasal respirators to breathe the helium-nitrogen-oxygen ternary gas mixture;

[0022] S9: When the cabin pressure drops below 1.8 bar, the operator removes the oronasal mask respirator, wears a decompression oxygen inhalation device, and exits the cabin after completing the decompression process by alternating between oxygen and compressed air.

[0023] S10, after the knife changing operator leaves the chamber, he will be checked again by the diving doctor. After confirming that there is no abnormality, he will rest and participate in the operation again after a 24-hour interval. After 6 consecutive operations, he will enter the hyperbaric oxygen chamber for treatment.

[0024] Preferably, in step S3, the shield machine's own pressurizing device is started to fill the cabin with compressed air at a rate of 1.5 bar / min.

[0025] Preferably, in step S8, the decompression depth of the first station is determined according to the nitrogen partial pressure in the configured helium-nitrogen-oxygen ternary gas mixture; the decompression is performed from the operating pressure to the decompression depth of the first station at a steady rate; and the dwell pressure and time of each decompression stage are controlled based on the decompression depth of the first station according to the air decompression table and the operating time.

[0026] Preferably, in step S9, the decompression oxygen inhalation device alternately supplies air at an interval of 25 minutes of breathing oxygen and 5 minutes of compressed air at a pressure below 1.8 bar until decompression is completed.

[0027] The beneficial effects of the present invention are as follows:

[0028] The shield machine tool changing system under pressure and its construction method proposed in the present invention adopt a helium-nitrogen-oxygen ternary mixed gas operation mode under non-saturated high pressure, breaking through the technical bottleneck of low efficiency of traditional air pressure operation above 5 bar and inability to implement above 6 bar, and effectively solving the problem of difficulty in carrying out tool changing operation under high pressure conditions. By accurately controlling the ratio of the helium-nitrogen-oxygen ternary mixed gas, especially strictly controlling the nitrogen partial pressure below 4.0ATA, the risk of nitrogen narcosis for workers in high-pressure environments is effectively avoided. While significantly improving the safety of operations, it also expands the pressure range that the system can adapt to, and improves the feasible depth and intensity of shield machine tool pressure operations. Compared with traditional saturation diving operations that rely on living cabins, shuttle cabins and complex gas replacement systems, the present invention eliminates the setting of living cabins and shuttle cabins. Workers can directly enter the human cabin for pressurization and wear oral and nasal mask respirators to breathe helium-nitrogen-oxygen mixtures, which simplifies the system structure, shortens the operation preparation cycle, improves the response speed and operation frequency, and significantly enhances the flexibility and efficiency of construction organization. In addition, the present invention adopts a standardized and modular mixed gas distribution system, combined with a scientific decompression and oxygen inhalation process, which effectively extends the single operation time and improves the comfort and continuity of the operation. At the same time, the system combines functions such as cabin pressurization control, equipment redundancy configuration, communication and alarm mechanisms to ensure the stability and safety of the entire operation process. The overall system operates reliably and the gas production scheme is flexible. It not only meets the requirements of high-pressure non-saturated operations for the accuracy of the mixed gas, but also significantly reduces helium consumption and operating costs. It takes into account safety, economy and practicality, and is suitable for continuous pressurized tool changing operations under deep burial and high-pressure conditions. It has wide promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is an overall schematic diagram of a shield machine tool changing system under pressure according to an embodiment of the present invention;

[0030] Figure 2 It is a flow chart of a construction method of a shield machine tool changing system with pressure according to an embodiment of the present invention.

[0031] Figure numerals: 1-mixed gas distribution device; 11-automatic gas distribution assembly; 12-manual gas distribution assembly; 13-mixed gas storage tank; 14-No. 1 mixed gas row; 15-back pressure valve; 16-No. 2 mixed gas row; 2-oronasal mask respirator; 3-decompression oxygen inhalation device; 4-man cabin; 5-oxygen supply device; 6-pressurization device; 7-intercom; 8-alarm device; 9-control room. DETAILED DESCRIPTION

[0032] 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the present invention.

[0033] 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 so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art 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, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0034] See also Figure 1 This embodiment provides a shield machine tool changing system under pressure, suitable for non-saturated pressurized tool changing operations. Saturated high-pressure operations refer to operations in an environment with pressure higher than atmospheric pressure, with continuous exposure for 24 hours or more, resulting in the saturation of the body's tissues with inert gases. Non-saturated high-pressure operations, on the other hand, refer to operations in a high-pressure environment without entering a saturated diving state, thereby reducing pressurization and decompression time and improving operational efficiency. This embodiment achieves more efficient and safe entry and tool changing operations in a high-pressure environment through a non-saturated method, overcoming the limitations of traditional air pressurized operations, which are inefficient above 5 bar and unable to enter the cabin above 6 bar.

[0035] The shield machine's pressurized tool-changing system includes a mixed gas distribution device 1, an oronasal mask respirator 2, a decompression oxygen inhalation device 3, and a manhole 4. The mixed gas distribution device 1 is the core gas supply unit of the entire system, used to configure and provide a helium-nitrogen-oxygen ternary gas mixture suitable for high-pressure operations. The mixed gas distribution device 1 includes an automatic distribution component 11, a manual distribution component 12, and a mixed gas storage tank 13. The automatic and manual distribution components 11 and 12 constitute the system's dual-mode mixing path, allowing for automatic and manual adjustment of the gas ratio, enhancing the system's operational flexibility and redundancy. The mixed gas storage tank 13 is used to store the prepared mixed gas, ensuring supply continuity and pressure stability. The automatic or manual distribution components 11 and 12 mix compressed air, oxygen, and helium, the three primary raw gas sources. The mixing ratio is set based on operating pressure, nitrogen partial pressure limits, and oxygen toxicity risks to achieve the optimal breathing gas mixture. A well-proportioned helium, nitrogen, and oxygen ternary gas mixture is stored in mixed gas storage tank 13. Mixed gas storage tank 13 has high-pressure capacity, allowing for a continuous supply of gas to multiple workers within a short period of time. Personnel cabin 4 is used for pressurization and decompression before and after workers undergo pressure work. As a closed, pressure-controlled cabin, personnel cabin 4 ensures safe transitions between workers in high-pressure environments and serves as a critical buffer between the normal-pressure and high-pressure chambers. The cabin is equipped with an oronasal mask respirator 2 and a decompression oxygen inhalation device 3. Oronasal mask respirator 2 is a wearable breathing terminal connected to mixed gas storage tank 13 via a high-pressure hose, supplying the ternary gas mixture to workers during operations. The high-pressure hose is pressure-resistant and flexible, accommodating the movement of personnel within the cabin and maintaining a stable gas supply. Decompression oxygen inhalation device 3 is connected to oxygen supply device 5 via a gas supply line, providing workers with an oxygen channel for inhalation during decompression to accelerate the desaturation process. Oxygen supply device 5 is a dedicated medical-grade oxygen source system that ensures oxygen purity and flow control accuracy, providing adequate protection for workers during the desaturation phase.

[0036] In the mixed gas distribution device 1, air, oxygen and helium pass through the pressure-stabilizing valve, transmitter, manual valve, filter, flow controller and check valve of the automatic gas distribution component 11. Air, oxygen and helium are the basic gas sources for the ternary mixed gas, and pass through various control and purification components in the automatic gas distribution component 11 in sequence. The pressure-stabilizing valve is used to preliminarily control the stability of the gas source pressure, the transmitter is used to monitor parameters in real time, the manual valve and check valve are used to control the flow direction and prevent backflow, the filter is used to remove impurities, and the flow controller is used to accurately control the proportion of each gas, and then enter the No. 1 mixing row 14. The No. 1 mixing row 14 serves as a primary mixing pipe to receive and mix gas components from different gas sources. The pressure is adjusted by the back pressure valve 15, which is used to apply reverse pressure to the mixed gas to maintain a constant pressure in the mixed gas pipeline, ensuring a uniform and stable mixing effect. The gas flows into the No. 2 mixed gas row 16 through two gas supply pipes. The two gas supply pipes are designed as one for use and one for backup, enhancing the reliability and continuous operation capability of the system. The No. 2 mixed gas row 16 acts as an intermediate buffer and pressure integration link to further stably transport the initial mixed gas to the gas storage unit, and finally reaches the mixed gas storage tank 13. The mixed gas storage tank 13 provides the system with high-pressure, clean, and appropriately proportioned mixed gas storage, which is convenient for supplying gas to the operation terminal at any time. The No. 2 mixed gas row 16 is connected to the manual gas distribution component 12. The manual gas distribution component 12 can be switched for use when the automatic gas distribution is abnormal or requires manual intervention and adjustment, realizing redundant switching and safety protection of the gas mixing mode, thereby improving the adaptability and safety performance of the entire system in complex construction environments.

[0037] Furthermore, the man cabin 4 is connected to the shield machine's built-in pressurization device 6. This device regulates the cabin pressure by injecting compressed air into the man cabin 4. The pressurization device 6 is capable of automatically adjusting the gas injection rate and upper pressure limit, allowing it to quickly adjust the cabin environment to a pressure consistent with the operating chamber based on operational requirements, ensuring safe and efficient entry and exit of personnel. The man cabin 4 is equipped with an intercom 7, a tablet, and an alarm device 8. The intercom 7 and tablet are used by workers to communicate with the control room 9. The intercom 7 is a wireless or wired voice communication device, ensuring real-time communication between the workers inside the cabin and the control room 9. The tablet is used for text communication when voice communication is inconvenient in high-pressure environments, improving operational stability and emergency response capabilities. The alarm device 8 is used to identify the worker's working status and upload this information to the control room 9. Equipped with various sensors, such as heart rate and posture monitoring units, the alarm device 8 can automatically detect abnormal personnel status and promptly issue a signal, allowing the control room 9 to remotely intervene or respond to instructions, thereby enhancing operational safety.

[0038] In this embodiment, the decompression oxygen inhalation device 3 uses a thin film hood, including a transparent sealed hood body. The transparent sealed hood body is used to completely seal the operator's head and neck. The hood body is made of a soft and transparent material, has good sealing and comfort, and can prevent the leakage of ambient gas during decompression. At the same time, through the mechanical automatic oxygen supply and mechanical automatic oxygen exhaust functions, the mechanical automatic oxygen supply can provide a constant flow of oxygen into the hood without manual adjustment, and the mechanical automatic oxygen exhaust function automatically exhausts excess gas according to the internal air pressure to prevent oxygen accumulation from causing a hyperoxic environment. The thin film hood includes an oxygen supply and exhaust control module. The oxygen supply and exhaust control module automatically adjusts the oxygen exhaust volume according to the oxygen supply flow rate. The oxygen supply and exhaust control module can implement dynamic adjustment logic for multiple supply and multiple exhaust, or no supply and no exhaust, thereby making the use of gas inside the hood more efficient, ensuring smooth breathing and safe gas composition during the oxygen inhalation and exhaust process.

[0039] In this embodiment, the partial pressure of oxygen in the ternary mixed gas is Po 1.4-2.0ATA, and the partial pressure of nitrogen is P N ≤4 ATA, with the remainder being helium. This gas ratio balances oxygen demand during operations with inert gas desaturation efficiency. The oxygen partial pressure is controlled within the safe range for human metabolism, while the nitrogen partial pressure is limited to below 4 ATA to prevent high-pressure nitrogen narcosis. The remainder is supplemented by helium to reduce the mixture density and reduce breathing resistance, thereby ensuring safe and efficient life support during high-pressure operations. The ratio of the helium-nitrogen-oxygen ternary gas mixture not only considers respiratory safety and nitrogen narcosis risk control during operations, but also comprehensively considers decompression efficiency after the operation. Specifically, nitrogen is used as the inert gas basis for determining the most unfavorable water depth in the gas mixture. This means that nitrogen partial pressure controls the dissolution and release of tissue gases in the decompression plan. This significantly shortens decompression time compared to traditional decompression models that use helium as the basis for the most unfavorable water depth. Due to helium's faster diffusion rate and more sensitive tissue saturation and desaturation processes, decompression planning based on helium requires longer step-by-step decompression to prevent bubble precipitation and decompression sickness. The present invention rationally controls the nitrogen partial pressure and limits it to below 4.0 ATA, which not only effectively avoids nitrogen narcosis, but also reduces the release control intensity of the most unfavorable tissue gas in the decompression path planning, thereby shortening the decompression time and improving the overall operation efficiency and the recovery speed of personnel after the operation.

[0040] See also Figure 2 Another embodiment of the present invention further discloses a construction method based on the above-mentioned shield belt pressure tool changing system, comprising the following steps:

[0041] S1: The diving doctor conducts a special physical examination on the knife-changing operator to confirm that the pulse, blood oxygen saturation and physical condition are normal before preparing to enter the cabin. In this step, the special physical examination is used to eliminate the health risks that may exist among the personnel who are not suitable for high-pressure operations, and to ensure that the knife-changing operator has the basic physical conditions to enter the high-pressure environment. It is an important prerequisite for ensuring the safety of the operation.

[0042] S2. After the working personnel leave the cabin, the tool changing personnel of this shift will inspect and clean the breathing air system, and the safety officer will check whether they are carrying flammable and explosive items. In this step, the breathing air system mainly includes an oral and nasal mask respirator and a decompression oxygen inhalation device. The inspection and cleaning work ensures the stability of the flow of the gas supply system and the cleanliness of the gas source. The safety officer will remove dangerous goods such as lighters and cigarettes to prevent safety accidents in a high-pressure oxygen-rich environment.

[0043] In step S3, the tool changer enters cabin 4 and checks the tools and communication systems. The operator then pressurizes cabin 4. In this step, cabin 4 serves as a transitional chamber between pressurization and depressurization for the tool changer. Compressed air is injected into cabin 4 via the shield machine's built-in pressurizing device 6 to adjust the cabin pressure to the required level. Specifically, pressurizing device 6 fills the cabin at a rate of 1.5 bar / min.

[0044] S4, when the pressure in the cabin reaches 2.4 bar, the operator starts to wear the oronasal mask respirator 2 to breathe the ternary mixed gas. When the pressure reaches 3.0 bar, the pressurization is stopped and the oronasal mask respirator 2 is confirmed to be working normally through voice or handwritten text. After confirming that there is no abnormality, the pressure is increased to the same level as the excavation chamber pressure in the human cabin 4 and then the pressurization is stopped; in this step, the ternary mixed gas is prepared by the mixed gas distribution device 1, stored in the mixed gas storage tank 13, and transported to the oronasal mask respirator 2 through a high-pressure hose. Voice confirmation relies on the intercom 7, and handwritten communication can be completed through the handwriting board set in the human cabin 4. This step is used to ensure the normal operation of the respiratory system and smoothly transition to the high-pressure working state.

[0045] S5, the tool changing operator opens the door between the human cabin 4 and the air cushion chamber, and three operators enter the air cushion chamber, and then open the door between the air cushion chamber and the mud and water chamber to start the operation; in this step, the air cushion chamber serves as an intermediate transition chamber to achieve pressure balance between the human cabin 4 and the mud and water chamber, avoiding the direct opening of the door which causes violent flow of gas. The operators enter the chamber in stages to operate, which helps to ensure a smooth and safe pressure control process.

[0046] S6, during the operation, one person is responsible for observation and delivery in the air cushion chamber, and two people enter the mud and water chamber to perform the tool changing operation; in this step, the personnel in the air cushion chamber are responsible for observing the face, tool delivery and observing the operation of the tool changing personnel in the mud and water chamber, and can also maintain real-time communication with the control room 9 to ensure the smooth flow of information and emergency response capabilities during the operation. Clear division of labor can improve operational efficiency.

[0047] S7, 10 minutes before the end of the operation cycle, the operator notifies the operators to stop the operation, organizes the tools and closes the connecting door between the mud and water tank and the air cushion tank, and the operators return to the man cabin 4; in this step, through early warning, tool organization and cabin door closure, preparations are made for subsequent decompression operations, ensuring that the pressure and environment in the operation cabin are in a controllable state, reducing the risk of emergencies during the decompression process.

[0048] S8, after all the operating personnel have entered the man cabin 4 and closed the cabin door, the operator starts the decompression procedure, and the operating personnel continue to wear the oronasal mask respirator 2 to breathe the helium-nitrogen-oxygen ternary gas mixture; in this step, the oronasal mask respirator 2 is still required to maintain the breathing of the mixed gas during the decompression process to avoid the risk of decompression sickness caused by directly inhaling compressed air when the pressure is still high.

[0049] S9: When the pressure in the cabin 4 drops below 1.8 bar, the operator removes the oronasal mask respirator 2 and puts on the decompression oxygen inhalation device 3. After completing the decompression process by alternating between oxygen and compressed air, the operator exits the cabin. In this step, the decompression oxygen inhalation device 3 is a thin-film hood structure that completely seals the operator's head and neck. It uses a mechanical automatic oxygen supply and exhaust to control the desaturation rate. By connecting to the oxygen supply device 5, the alternating air supply method improves decompression efficiency and comfort. Specifically, the decompression oxygen inhalation device 3 alternates between breathing oxygen for 25 minutes and compressed air for 5 minutes at a pressure below 1.8 bar until decompression is complete.

[0050] S10: After the knife-changing operator leaves the chamber, he / she will be checked again by the diving doctor. After confirming that there is no abnormality, he / she will rest and participate in the operation again after a 24-hour interval. After working for 6 consecutive times, he / she will enter the hyperbaric oxygen chamber for treatment. In this step, the physical examination and compulsory rest system after leaving the chamber are effective measures proposed by the present invention to protect the health and safety of the operators based on the characteristics of high-pressure operations, and have strong ergonomic adaptability.

[0051] In a specific embodiment, the preset operating pressure is 5.7 bar, and the ternary gas mixture is set to a nitrogen partial pressure of 2.9ATA, an oxygen partial pressure of 1.6ATA, and a helium partial pressure of 2.2ATA. The partial pressures of the three gases are precisely controlled, and the nitrogen partial pressure is strictly controlled below 4.0ATA to effectively avoid the risk of high-pressure nitrogen narcosis. The oxygen partial pressure is maintained within the safe range of human metabolism, and the helium partial pressure is used to reduce the density of the mixture and breathing resistance. The operation residence time is 70 minutes, that is, the continuous operation time of the operator in the mud and water tank to maintain a high-pressure mixed gas breathing environment. This time is set in combination with the tool changing task volume and the pressure endurance of the personnel to ensure that the task is completed while avoiding overtime exposure. In this embodiment, the ratio of the helium, nitrogen, and oxygen ternary gas mixture not only takes into account the respiratory safety and nitrogen narcosis risk control during the operation, but also comprehensively considers the decompression efficiency after the operation. Specifically, the use of nitrogen as the inert gas basis for determining the most unfavorable water depth in the gas mixture—that is, the use of nitrogen partial pressure as a control factor for tissue gas dissolution and release in the decompression scheme—can significantly shorten decompression time compared to traditional decompression models that use helium as the basis for the most unfavorable water depth. Because helium diffuses more rapidly and its tissue saturation and desaturation processes are more sensitive, decompression planning based on helium requires longer step-by-step decompression times to prevent bubble formation and the risk of decompression sickness. However, by rationally controlling nitrogen partial pressure (for example, limiting it to below 4.0 ATA), the present invention effectively avoids nitrogen narcosis and reduces the intensity of control over the release of the most unfavorable tissue gas during decompression path planning, thereby shortening decompression time and improving overall operational efficiency and post-operation recovery.

[0052] Furthermore, in step S8, the first decompression depth is determined based on the nitrogen partial pressure in the configured helium-nitrogen-oxygen ternary gas mixture; decompression is performed at a steady rate from the operating pressure to the first decompression depth; and based on the first decompression depth, the dwell pressure and duration of each decompression stage are controlled according to the air decompression table and the operating time. This step effectively reduces the risk of inert gas retention during the decompression process by controlling the nitrogen partial pressure. Scientific decompression control, combined with the air decompression table, ensures a safe and efficient desaturation process for tool changers, thereby reducing the occurrence of decompression complications.

[0053] Specifically, the nitrogen partial pressure P in the mixed gas can be obtained first. 氮 and operating pressure P 总 , the unit is ATA, through the formula P 空 =P 氮 / 0.78 can be used to obtain the equivalent air pressure under this nitrogen partial pressure. Then calculate the reference values ​​h1 and h2 of the first decompression depth in meters: h1=(P 空 -1)×10,h2=((P 总-1) / 2)×10. Among them, h1 represents the equivalent decompression depth converted according to nitrogen partial pressure, and h2 represents the conservative decompression depth calculated based on half of the total operating pressure. Both take into account the initial pressure difference and depth buffer requirements required for gas desaturation. Then obtain the larger value of the above two results h1 and h2. Select a higher decompression depth to ensure safety and prevent bubble formation or uneven tissue saturation due to excessive decompression. Finally, the decompression depth of the first stop is determined to be h=max(h1, h2)+(3~6), in m. By adding a safety redundancy of 3 to 6 meters on the basis of the maximum reference value, individual differences, operational errors or potential abnormal physiological reactions can be effectively prevented, thereby improving the safety and reliability of the entire decompression process. Taking the preset operating pressure of 5.7 bar (6.7ATA), the ternary mixed gas is set to a nitrogen partial pressure of 2.9ATA, an oxygen partial pressure of 1.6ATA, and a helium partial pressure of 2.2ATA as an example to calculate: P 空 =P 氮 / 0.78≈3.72 ATA; h1=(3.72-1)×10=27.2 meters; h2=(6.7-1) / 2×10=28.5 meters; finally, h=max(27.2, 28.5)+(3-6)=31.5-34.5 meters. This altitude and operation time can be used to determine the decompression plan.

[0054] During the pressurization process of the present invention, the operator breathes a helium-nitrogen-oxygen ternary gas mixture in the human cabin 4 by wearing an oronasal mask respirator 2. The partial pressure of the gases in the body generated by the breathing process increases synchronously with the gradual increase in the ambient pressure of the human cabin 4, thereby achieving consistency between the "internal pressurization" process in the operator's body and the "external pressurization" process in the human cabin 4. As the human cabin 4 is continuously pressurized at a set rate by the pressurizing device 6, the ambient pressure in the cabin gradually rises. The operator continues to inhale the high-pressure ternary gas mixture, and gases are continuously exchanged between the alveoli and the blood, causing the dissolved partial pressures of gases such as nitrogen, helium, and oxygen in the body to rise synchronously with the cabin pressure. Ultimately, the operator's body pressure and the cabin pressure are balanced within a specified time, thereby avoiding pressure injuries caused by an imbalance in the internal and external pressure differences and ensuring the safety and physiological stability of the personnel during the high-pressure adaptation process. During the decompression process of the present invention, the operator breathes a helium-nitrogen-oxygen ternary gas mixture or a decompression oxygen inhalation device 3 in the human cabin 4 by wearing an oronasal mask respirator 2. The partial pressure of the gas in the body generated during the breathing process decreases synchronously with the gradual decrease in the ambient pressure of the human cabin 4. As the human cabin 4 gradually decompresses at a set rate through the outlet valve, the air pressure in the cabin continues to drop. The inert components (such as nitrogen and helium) in the gas inhaled by the operator maintain a partial pressure gradient between the alveoli and the blood that is synchronized with the outside world, thereby achieving consistency between the "internal decompression" process in the operator's body and the "external decompression" process in the human cabin 4. The amount of dissolved gas and the escape rate change synchronously during the decompression process, which can effectively avoid bubble precipitation caused by imbalance of the internal and external pressure difference, and ensure the physiological stability of the decompression process and the safety of the operator.

[0055] From an economic point of view, in actual application, compared with the use of saturated pressure after exceeding 6 bar, the mixed gas pressure operation is priced per bin, with a cost of 40,000 yuan per bin. The price is adjusted with the operating pressure, and the number of bins for each operation is adjusted according to the actual situation on site. According to 80 bins per operation, the cost is 3.2 million, while the average one-time cost of saturated pressure exceeds 15 million. The mixed gas pressure tool changing system in this embodiment uses an unsaturated helium, nitrogen and oxygen ternary mixed gas method to perform tool changing operations. It uses a standardized human cabin 4 and a gas distribution device 1 to complete high-pressure cabin entry and gas supply support. There is no need to build a dedicated living cabin and shuttle cabin, which effectively reduces the initial investment cost and the cost of a single operation bin. It is suitable for large-scale, high-frequency high-pressure operation scenarios, and the economic benefits are significantly better than the traditional saturated pressure scheme. From a safety point of view, the present invention uses this tool changing system and its construction method to increase the operation time by reducing the nitrogen partial pressure. The effective operation time in the entire operation process accounts for 60% of the limit operation time, and the operation safety is greatly improved. By controlling the nitrogen partial pressure in the mixed gas distribution device 1 to be below 4.0ATA, and using the oronasal mask respirator 2 to stably supply gas to the operator, high-pressure and long-term operation is achieved, while ensuring that the operator is always within the safe physiological threshold during the operation, effectively reducing the risk of nitrogen narcosis and decompression sickness, and improving the continuity and reliability of the operation. From an environmental protection perspective, the present invention does not require the traditional saturated pressure operation before the tunnel door breaking and gas replacement operations. The human cabin 4 is directly pressurized to enter the working chamber to carry out the operation, avoiding the occurrence of a large number of polluting operation steps, and has good environmental friendliness. From the perspective of construction period, using this tool changing system and its construction method, first, the equipment can be brought to the site and debugged in advance without affecting the on-site shield construction; second, the entire tool changing operation time can be adjusted according to actual conditions; finally, the shield construction can quickly achieve the warehouse operation when encountering emergencies. Compared with saturated pressure, which requires a lot of pre-preparation time, it can save construction period to the greatest extent. The system is highly modularized. Components such as the mixed gas distribution device 1, the man cabin 4, and the control room 9 can be transported and quickly deployed as a whole, allowing tool changing equipment and shield construction to proceed in parallel. When an unexpected tool change is required, cabin pressurization and operational preparation can be completed quickly, significantly improving the emergency response capability and schedule control efficiency of shield construction.

[0056] In summary, the present invention discloses a shield pressurized tool changing system and a construction method thereof. The system includes key modules such as a mixed gas distribution device 1, an oronasal mask respirator 2, a decompression oxygen inhalation device 3 and a human cabin 4. A helium-nitrogen-oxygen ternary mixed gas is used to provide a non-saturated high-pressure breathing environment for the operating personnel. Combined with a scientific pressurization and decompression control process, a safe and efficient cabin entry and tool changing operation under high-pressure conditions is achieved. The present invention effectively breaks through the technical bottleneck of traditional compressed air pressurized operations with low efficiency above 5 bar and inability to be implemented above 6 bar, and avoids the problems of long preparation period for saturated pressurized operations, cumbersome equipment, slow response and high operation risks. It can flexibly adjust the operation strategy under high-pressure environment, and significantly improve the operation efficiency while ensuring the safety of the operation. Through the system integration and construction method of the present invention, it can effectively solve the practical problems of low efficiency of high-pressure operations, long decompression process, high cost of helium use, bulky equipment, and cumbersome operation in the existing technology. Compared with traditional saturated diving pressurized operations, this invention significantly simplifies the operational process, shortens preparation time, and improves response speed and efficiency, all while ensuring operational safety. It also effectively reduces operating costs and the physiological burden on operators, resulting in greater engineering adaptability and promotional value. This technology provides an efficient and reliable solution for shield construction during unsaturated, high-pressure operations in deep, complex strata. It is of great significance for promoting the standardization of shield operations and the safety of high-pressure operations, and has broad prospects for industrialization and engineering application.

[0057] 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 can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that it is still possible to modify the technical solutions described in the above embodiments, or to make equivalent replacements for some of the technical features therein. 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 construction method based on a shield pressure cutter changing system, characterized in that: The invention is suitable for non-saturated pressurized tool changing operation, and does not require the setting of a living cabin and a shuttle cabin. The shield pressurized tool changing system comprises a mixed gas distribution device (1), an oral and nasal mask respirator (2), a decompression oxygen inhalation device (3) and a human cabin (4). The mixed gas distribution device (1) comprises an automatic gas distribution component (11), a manual gas distribution component (12) and a mixed gas storage tank (13). The automatic gas distribution component (11) or the manual gas distribution component (12) mixes and proportions compressed air, oxygen and helium, and stores the well-proportioned helium-nitrogen-oxygen ternary mixed gas in the mixed gas storage tank (13). The human cabin (4) is used for operation. For pressurization and decompression before and after work, a mouth-nose mask respirator (2) and a decompression oxygen inhalation device (3) are provided in the cabin. The mouth-nose mask respirator (2) is connected to the mixed gas storage tank (13) via a high-pressure hose and is used to supply the ternary mixed gas to the operator during the operation. The decompression oxygen inhalation device (3) is connected to the oxygen supply device (5) via a gas supply pipeline and is used to provide the operator with an oxygen inhalation channel during the decompression process to accelerate the desaturation process. The partial pressure PO of oxygen in the ternary mixed gas is 1.4-2.0ATA, the partial pressure PN of nitrogen is ≤4ATA, and the rest is helium. The construction method comprises the following steps: S1: The diving doctor will conduct a special physical examination on the knife change operator, confirming that the pulse, blood oxygen saturation and physical condition are normal before preparing to enter the cabin; S2: After the working personnel leave the cabin, the tool change personnel of this shift will check and clean the breathing air system, and the safety officer will check whether they are carrying flammable and explosive items; S3, the tool changing operator enters the cabin (4), checks the tools and the communication system, and then the operator pressurizes the cabin (4); S4, when the pressure in the cabin reaches 2.4 bar, the operator starts wearing a mouth-nose respirator (2) to breathe the ternary mixed gas. When the pressure reaches 3.0 bar, the pressurization is stopped and the operator confirms that the mouth-nose respirator (2) is working normally through voice or handwritten text. After confirming that there is no abnormality, the pressurization is stopped after the pressure in the cabin (4) is consistent with the pressure in the excavation chamber; S5, the tool changing operator opens the door between the man cabin (4) and the air cushion chamber, and three operators enter the air cushion chamber, then open the door between the air cushion chamber and the mud and water chamber, and start the operation; During S6, one person is responsible for observation and delivery in the air cushion chamber, and two people enter the mud and water chamber to perform the tool change operation; S7, 10 minutes before the end of the operation cycle, the operator notifies the operators to stop the operation, organizes the tools and closes the connecting door between the mud and water tank and the air cushion tank, and the operators return to the cabin (4); S8, after all the operating personnel have entered the cabin (4) and closed the cabin door, the operator starts the decompression procedure, and the operating personnel continue to wear the mouth and nose mask respirator (2) to breathe the helium, nitrogen and oxygen ternary mixture; S9, when the pressure in the cabin (4) drops below 1.8 bar, the operator removes the mouth-nose respirator (2), wears the decompression oxygen inhalation device (3), and exits the cabin after completing the decompression according to the set process of alternating oxygen and compressed air inhalation; S10: After leaving the chamber, the operator will be re-examined by the diving doctor. After confirming that there are no abnormalities, the operator will rest and wait for 24 hours before participating in the operation again. After six consecutive operations, the operator will enter the hyperbaric oxygen chamber for treatment. In step S8, the decompression depth of the first station is determined according to the nitrogen partial pressure in the configured helium, nitrogen and oxygen ternary mixed gas; the nitrogen partial pressure P in the mixed gas is obtained. 氮 and operating pressure P 总 , the unit is ATA, through the formula P 空 =P 氮 / 0.78 can be used to obtain the equivalent air pressure under the nitrogen partial pressure; calculate the reference values ​​h1 and h2 of the first station decompression depth in meters: h1=(P 空 -1)×10,h2=((P 总 -1) / 2)×10; obtain the larger value of the two results h1 and h2; and finally determine the decompression depth of the first station h=max(h1,h2)+(3-6), in meters.

2. The construction method according to claim 1, characterized in that: In the mixed gas distribution device (1), air, oxygen and helium pass through the pressure regulating valve, transmitter, manual valve, filter, flow controller and check valve of the automatic gas distribution assembly (11), enter the No. 1 mixed gas row (14), adjust the pressure through the back pressure valve (15), flow into the No. 2 mixed gas row (16) through two gas supply pipes, and finally reach the mixed gas storage tank (13). The No. 2 mixed gas row (16) is connected to the manual gas distribution assembly (12).

3. The construction method according to claim 1, characterized in that: The man cabin (4) is connected to a pressurizing device (6) provided with the shield machine, and the pressurizing device (6) regulates the pressure in the cabin by filling the man cabin (4) with compressed air.

4. The construction method according to claim 1, characterized in that: An intercom (7), a handwriting board, and an alarm device (8) are provided in the man cabin (4). The intercom (7) and the handwriting board are used for the operator to communicate with the control room (9). The alarm device (8) is used to identify the working status of the operator and upload the working status information to the control room (9).

5. The construction method according to claim 1, characterized in that: The decompression oxygen inhalation device (3) adopts a thin film head cover, comprising a transparent sealing cover body, the transparent sealing cover body is used to completely seal the head and neck of the operator, and has the functions of mechanical automatic oxygen supply and mechanical automatic oxygen exhaust.

6. The construction method according to claim 1, characterized in that: In step S3, the shield machine's own pressurizing device (6) is started to fill the cabin with compressed air at a rate of 1.5 bar / min.

7. The construction method according to claim 1, characterized in that: In step S8, the pressure is reduced from the operating pressure to the decompression depth of the first station at a steady rate; based on the decompression depth of the first station, the dwell pressure and time of each decompression stage are controlled according to the air decompression table and the operating time.

8. The construction method according to claim 1, characterized in that: In step S9, the decompression oxygen inhalation device (3) supplies air alternately at a pressure below 1.8 bar, with an interval of 25 minutes of oxygen breathing and 5 minutes of compressed air breathing, until decompression is completed.

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