High-temperature tunnel excavation face rapid cooling system and method

Abstract

This invention discloses a rapid cooling system for high-temperature tunnel excavation faces, comprising a carbon dioxide circulating spray cooling mechanism and an annular mounting frame disposed on the carbon dioxide circulating spray cooling mechanism near the excavation face; the annular mounting frame is evenly distributed with multiple nozzles; the carbon dioxide circulating spray cooling mechanism includes a liquid CO2 storage vehicle, a gas supply pipe connected to the liquid CO2 storage vehicle, and a waste gas recovery pipe; the outlet of the gas supply pipe is connected to the nozzles, and the inlet of the waste gas recovery pipe is disposed on the annular mounting frame; this invention also discloses a rapid cooling method for high-temperature tunnel excavation faces, which can recycle the refrigerant during the spray cooling process, saving spray cooling costs while saving water and electricity resources, and has the characteristics of being economical, environmentally friendly, safe and effective, and simple to operate.

Description

Technical Field

[0001] This invention relates to the field of heat hazard prevention and mitigation technology in underground space and tunnel engineering, and in particular to a rapid cooling system and method for high-temperature tunnel excavation faces. Background Technology

[0002] The Qinghai-Tibet Plateau and its surrounding areas, influenced by intense plate compression and tectonic activity in the tunnel sites, have resulted in numerous long, large, and deep tunnels traversing the Hengduan Mountains exhibiting the "three highs" phenomenon: high altitude, high ground stress, and high ground temperature, with geothermal disasters being the most frequent issue. Preliminary statistics indicate that there are at least 10 high-temperature tunnels along the Sichuan-Tibet Railway currently under construction, with ground temperatures ranging from 28.7 to 89.0℃. High ground temperatures firstly deteriorate the construction environment, reduce labor productivity, and seriously threaten the health and safety of construction workers; secondly, high temperatures inside the tunnels lead to reduced efficiency and increased malfunctions of mechanical equipment; thirdly, they affect the selection of tunnel construction materials such as drilling and blasting explosives; simultaneously, the additional thermal stress generated by high ground temperatures causes lining cracking, which is detrimental to the safety and durability of the lining structure; after the tunnels are completed and operational, the high temperatures will make tunnel maintenance and repair more difficult, leading to a significant increase in operating costs. Due to the increasingly severe heat damage suffered by the extra-long tunnels on the Qinghai-Tibet Plateau, high ground temperature hazards have become a major challenge for tunnel engineering construction and structural safety.

[0003] Currently, there are two main methods for controlling heat hazards during the construction of high-temperature tunnels, both domestically and internationally: the first is to use blast furnace cement and wet-sprayed concrete construction, and shorten the exposure time of the surrounding rock to reduce high-temperature damage; the second is a cooling technology that combines tunnel ventilation with local ventilation, and low-temperature cooling water with artificial ice making. According to domestic and international research results and engineering application effects, the above measures can reduce the impact of high geothermal temperatures to a certain extent. However, in long and ultra-long, deep tunnels, preventing heat hazards from high geothermal temperatures requires the installation of numerous ventilation ducts, which is limited by tunnel space. Furthermore, methods such as artificial ice making are costly, and the ice-making and transportation processes are time-consuming, not only slowing down construction but also interfering with construction. Additionally, ice making requires a large amount of water, and the added chemicals and wastewater from melting ice can pollute the environment. Therefore, there is currently no better technological innovation for controlling heat hazards during the construction of high-temperature tunnels, both domestically and internationally.

[0004] In the prior art, Chinese Patent Application No. 202110863928.2 discloses a rock-breaking tunneling device and its rock-breaking method, including: a driving device, a cutterhead and a cleaning mechanism, as well as a high-energy emission device, a pulsed liquid jet system, a real-time monitoring system, a temperature monitoring device, an intelligent control system and a recycling system, and an information acquisition device to collect data information from the real-time monitoring system.

[0005] In the prior art, the pulsed liquid jet system has a liquid injection port located on the front of the cutterhead, and the liquid injection port is located around the high-energy output port. It is used to spray low-temperature liquid to cause a rapid drop in rock temperature. A temperature monitoring device detects the rock temperature properties before tunneling to determine whether it is hot rock and transmits the signal to the intelligent control system. During tunneling, it monitors the heating temperature of the heating part of the tunnel face to be tunneled by the high-energy emission device. The pulsed liquid jet system includes a liquid recycling system, which includes an exhaust detection device, a solid-gas separation device, a CO2 gas refrigeration heat exchanger, a granular dry ice production device, and a pulsed liquid high-pressure injection pump, which are connected in sequence.

[0006] In comparison, it is evident that existing technologies only provide a portion of the functions attached to the cutterhead of rock-breaking tunneling devices, and are limited to the rock face in contact with the cutterhead. The range of cryogenic liquids used is unclear, and they do not address cooling technologies for a wider area near the excavation face of high-temperature tunnels. Secondly, the ultimate objectives of the inventions are inconsistent: existing technologies focus primarily on rock breaking, while this invention aims to ensure the working environment of the tunnel face and achieve rapid cooling and dust reduction at the excavation face of high-temperature tunnels. Thirdly, the integrated monitoring and transmission system of this invention can collect rock temperature and air pressure before and after cooling, and monitor the oxygen, carbon dioxide, and dust concentration characteristics of the excavation face in real time.

[0007] Liquid CO2 has a cooling temperature of -70℃, is simple to prepare, and uses abundant raw materials. It can be produced by collecting industrial and tunnel waste gas and pressing it through low-temperature equipment. Liquid CO2 itself is colorless, non-toxic, and odorless. Under pressure and low temperature, it turns into solid dry ice. It is stable, does not react with other substances, and is convenient and environmentally friendly. Using liquid CO2 for cooling can reduce water waste and effectively reduce hydration expansion and filtration loss problems. At the same time, liquid CO2 has a cooling effect. Therefore, the vaporization and direct sublimation of liquid CO2 on the high-temperature rock surface and rock cavities at the excavation face can rapidly cool the surrounding rock. Simultaneously, liquid CO2, sprayed at high speed onto the surface of the excavated surrounding rock with extremely high dust concentration, can achieve freezing, dust removal, and descaling. Therefore, using liquid CO2 for rapid cooling and dust and descaling of surrounding rock will not pollute the environment. It truly realizes the circulation and spraying of liquid CO2, making this invention an excellent waterless and energy-free rapid cooling method for high-temperature tunnels, and thus more feasible. Summary of the Invention

[0008] To address the problems existing in the prior art, the purpose of this invention is to provide a rapid cooling system and method for high-temperature tunnel excavation faces. This invention can recycle the refrigerant during the spray cooling process, saving spray cooling costs while also saving water and electricity resources. It has the characteristics of being economical, environmentally friendly, safe, effective, and easy to operate.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is: a rapid cooling system for high-temperature tunnel excavation faces, comprising a carbon dioxide circulating spray cooling mechanism and an annular mounting frame disposed on the carbon dioxide circulating spray cooling mechanism near the excavation face; the annular mounting frame is evenly distributed with multiple nozzles, the carbon dioxide circulating spray cooling mechanism includes a liquid CO2 storage vehicle, a gas supply pipe connected to the liquid CO2 storage vehicle, and a waste gas recovery pipe, the outlet of the gas supply pipe is connected to the nozzles, and the inlet of the waste gas recovery pipe is disposed on the annular mounting frame.

[0010] As a further improvement of the present invention, the angle between the nozzle and the excavation face is in the range of 30°-90°.

[0011] As a further improvement of the present invention, the gas transmission pipeline is connected to the liquid CO2 storage vehicle through a pipe with a flanged end. The pipeline is provided with a liquid pump, an electronic expansion valve, a pressure regulating valve, a CO2 gas-liquid separator and a compressor connected to the liquid CO2 storage vehicle in sequence according to the gas outlet direction. The compressor is connected to the nozzle.

[0012] As a further improvement of the present invention, the waste gas recovery pipeline is provided with a CO2 gas-liquid separator, a CO2 gas recovery device and a throttle valve connected to the annular mounting frame in sequence according to the waste gas recovery direction, and the throttle valve is connected to the liquid CO2 storage vehicle.

[0013] As a further improvement of the present invention, an automatic roller shutter is also provided on the annular mounting frame.

[0014] As a further improvement of the present invention, after the automatic roller shutter quickly falls and unfolds, a comprehensive monitoring and transmission system is set in the relatively closed cooling space formed with the excavation face. The comprehensive monitoring and transmission system is used to collect the temperature and pressure of the surrounding rock at different locations of the excavation face and in the closed cooling space, and to monitor the oxygen, carbon dioxide and dust concentrations of the excavation face in real time.

[0015] As a further improvement of the present invention, the carbon dioxide circulating spray cooling mechanism also includes a control module integrating a pressure sensor. The control module is used for automatic curtain retraction and extension, automatic adjustment of nozzle angle and flow rate, liquid CO2 pumping and pressurization, spray control switch, data acquisition and control, and data analysis.

[0016] This invention also provides a method for rapid cooling of the excavation face of a high-temperature tunnel, comprising the following steps:

[0017] (1) During the process of excavating and removing muck at the high-temperature tunnel excavation face to complete the anchor bolting and shotcreting, the rock temperature and air pressure before cooling are collected through the integrated monitoring and transmission system, and the oxygen, carbon dioxide and dust concentration characteristics of the excavation face are monitored in real time.

[0018] (2) Move the ring mounting frame and liquid CO2 storage car to the excavation face, open the pressure regulating valve, and at the same time, the liquid CO2 storage car delivers CO2 to the carbon dioxide circulating spray cooling mechanism. By controlling the liquid pump, the CO2 liquid in the CO2 storage car is delivered to the nozzle and sprayed out. When the pressure and temperature required for freezing are reached in the temporary chamber formed by the automatic roller shutter of the excavation face and the excavation face, the air in the chamber is discharged and the pressure regulating valve is closed.

[0019] (3) When the excavation face is cooled and frozen, the electronic expansion valve controls the amount of gas replenishment through the feedback signal of the pressure sensor, and the liquid CO2 storage vehicle delivers CO2 to the carbon dioxide circulating spray cooling mechanism; the carbon dioxide circulating spray cooling mechanism forms a closed cooling circuit for the CO2 working medium; the CO2 liquid in the CO2 gas-liquid separator in the carbon dioxide circulating spray cooling mechanism is transferred to the nozzle through the liquid pump, and a large number of jets containing small-sized droplets are generated by spraying to evenly cover the excavation face and achieve the freezing effect;

[0020] (4) The appropriate pressure and temperature in the temporary chamber formed by the automatic roller shutter and the excavation face can integrate the nozzle flow to form a CO2 flow field with uniform transverse direction and longitudinal temperature gradient. The above low temperature flow field is used to form a freezing mode of pre-cooling and then freezing the object to be frozen, thereby making full use of the cooling capacity of carbon dioxide in the freezing chamber temporarily formed by the automatic roller shutter and the excavation face.

[0021] (5) After spraying continuously for 30 minutes, the CO2 gas that has expanded and vaporized after cooling is drawn in by the CO2 gas recovery device, and then recompressed and cooled by the vehicle-mounted machine and sent back to the carbon dioxide circulation spray cooling mechanism, thereby realizing circulation spraying.

[0022] (6) After the spraying and freezing is completed, stop the carbon dioxide circulating spraying and cooling mechanism, close the nozzle regulating valve, stop the CO2 gas recovery device, open the pressure regulating valve, and discharge the remaining carbon dioxide; determine the temperature drop effect according to the data of the integrated monitoring and transmission module, and use the fan and duct control system to ventilate the excavation face; check the environmental parameters of the excavation face, remove the equipment, and carry out subsequent excavation and drilling construction.

[0023] The beneficial effects of this invention are:

[0024] 1. When liquid CO2 sublimates, it will produce a low temperature of -78℃. It can directly absorb heat from the objects it comes into contact with and sublimate into cold gas. The cold gas continues to come into contact with the high-temperature surrounding rock until the cold energy is completely absorbed and then discharged. In the above process, the latent heat accounts for about 84% of the total cooling capacity, which far exceeds the latent heat of ice and other substances. Through fluidized spraying, the object to be frozen can be cooled down rapidly in a short time, and the rock mass at the excavation face can be cooled down or even frozen quickly. This can achieve the cooling of the excavation face of water-rich soft surrounding rock and maintain the stability of the soft surrounding rock.

[0025] 2. This invention applies liquid CO2, which is widely used in food preservation and cooling, to high-temperature tunnels for the first time. This device is used to rapidly cool the excavation face of deep-buried tunnels. Because it realizes circulating spraying, it has the advantages of low energy consumption, the ability to directly obtain carbon dioxide from the air on-site using on-site equipment, turning carbon dioxide into a valuable resource while saving water and electricity resources, and minimizing pollution and disturbance to the geological environment.

[0026] 3. Due to the high rock temperature in the enclosed space of the high-temperature tunnel, liquid CO2 vaporizes on the high-temperature rock walls and inside the borehole, forming a natural cooling and refrigeration enclosed unit. Therefore, no additional heat exchanger or compressor equipment is required. At the same time, the device realizes the recovery and reuse of refrigerant during the spray cooling process, which greatly reduces refrigerant loss and saves cooling costs. The cooling and freezing process is carried out in a low-oxygen environment, which is suitable for deep-buried high-temperature tunnels that are widely found in high-altitude areas.

[0027] 4. Under suitable pressure and temperature conditions, the temporary chamber formed by the roller shutter and the excavation face, in conjunction with the nozzle, ensures the uniformity of spraying and enhances the effect of spraying and cooling. At the same time, the water mist in the process of CO2 vaporization also plays an auxiliary role in dust reduction and descaling, thereby achieving the purpose of rapid cooling and dust reduction of the high-temperature tunnel excavation face.

[0028] 5. The spray liquid is mainly composed of high-pressure condensate. The high-pressure condensate mainly plays an auxiliary role in pre-cooling, pressurization, and mixing, ensuring the safety of the system. At the same time, the refrigerant in different states in the cycle is rationally selected according to different uses, realizing the cascade utilization of energy, giving full play to the cooling capacity of CO2 in the cycle, and saving the operating energy consumption required for the cycle.

[0029] 6. In conjunction with ventilation fans and ducts, it ensures the working environment of the construction site on the basis of the traditional high-altitude tunnel basic implementation process. It is simple to operate, time-saving, efficient, and produces less environmental pollution. At the same time, it can achieve the effect of cooling and eliminating heat damage.

[0030] 7. The gasified carbon dioxide pre-cools the interior of the rock in front of the excavation face. The above process requires controlling the start and stop of the pumping unit to control the cooling process of the high rock temperature. The structure is simple and can be automated. No manual touch is required, which ensures the personal safety of the workers. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the carbon dioxide circulating spray cooling mechanism in an embodiment of the present invention;

[0033] Figure 3This is a schematic diagram of the rapid cooling system for the high-temperature tunnel excavation face in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the automatic roller blind after it is unfolded in an embodiment of the present invention.

[0035] Figure label:

[0036] 1. Liquid CO2 storage vehicle; 2. Circular mounting bracket; 3. Automatic roller shutter; 4. Infusion pump; 5. Nozzle; 6. Compressor; 7. Pressure regulating valve; 8. Waste gas recovery device; 9. Carbon dioxide gas-liquid separator; 10. Throttling valve; 11. Liquid CO2 connection pipeline; 12. Electronic expansion valve; 13. Control module integrating pressure sensor; 14. Integrated monitoring and transmission system. Detailed Implementation

[0037] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] Example

[0039] like Figures 1-3 As shown, a rapid cooling system for high-temperature tunnel excavation faces includes: an annular mounting frame 2 for the excavation face, an automatic roller shutter 3; a carbon dioxide circulating spray cooling mechanism including: a liquid CO2 storage vehicle 1, a liquid pump 4, a nozzle 5, a compressor 6, a pressure regulating valve 7, a waste gas recovery device 8, a carbon dioxide gas-liquid separator 9, a throttle valve 10, a liquid CO2 connecting pipeline 11, an electronic expansion valve 12, a control module 13 integrating a pressure sensor, and a comprehensive monitoring and transmission system 14.

[0040] The carbon dioxide circulating spray cooling mechanism is connected through a pipe 11 with flanges at the ends. The pipe is sequentially equipped with an electronic expansion valve 12, a control module 13 including a pressure sensor, a pressure regulating valve 7, a compressor 6, etc. The liquid CO2 storage vehicle connects the liquid CO2 to the carbon dioxide gas-liquid separator 9 through a liquid pump 4. The carbon dioxide gas-liquid separator is connected to the compressor 6 through a pipe. The compressor is connected to the nozzle 5 fixed on the annular mounting frame 2 at the excavation face through a pipe and pressurizes the liquid CO2 into the nozzle 5.

[0041] When the carbon dioxide circulating spray cooling mechanism sprays liquid CO2 onto the excavation face, the retractable automatic roller shutter 3 can quickly fall and unfold, forming a relatively enclosed cooling space in front of the excavation face. During the cooling process, the residual CO2 is connected to the carbon dioxide gas-liquid separator 9 and the throttle valve 10 through a pipeline. The waste gas recovery device 8 draws in the expanded and vaporized carbon dioxide gas after cooling and transports it back to the liquid CO2 storage vehicle to be recompressed and cooled into liquid CO2, thereby realizing circulating spraying.

[0042] In this embodiment, the liquid CO2 storage vehicle is equipped with multiple sets of insulated tanks with a pressure of 2.0 MPa. The CO2 gas is in a liquid state under on-board pressurization and is stored in the insulated tanks.

[0043] In this embodiment, when the high-temperature tunnel excavation face is rapidly cooled, liquid CO2 is sprayed out through the nozzle and injected into the rock fissures or soil pores to expand rapidly. The carbon dioxide gas-liquid separator 9 realizes the separation of liquid CO2 and gaseous CO2.

[0044] like Figure 4 As shown, after the automatic roller shutter 3 quickly falls and unfolds, a comprehensive monitoring and transmission system 14 is installed in the relatively enclosed cooling space formed with the excavation face. This system is used to collect the temperature and pressure of the surrounding rock at different locations on the excavation face and in the enclosed cooling space, and to monitor the oxygen, carbon dioxide, and dust concentrations at the excavation face in real time.

[0045] In this embodiment, the control module 13, which integrates a pressure sensor, integrates a retractable automatic roller shutter 3 retraction switch, a nozzle 5 angle and flow automatic control motor switch, a liquid CO2 pump pressurization and injection control switch, a data acquisition controller, and a data analysis display screen.

[0046] In existing technologies, cooling technologies that combine tunnel ventilation with local ventilation and low-temperature cold water with artificial ice making require the installation of numerous ventilation ducts in long and ultra-long buried deep tunnels, where tunnel space is limited. Secondly, methods such as artificial ice making are costly, and the ice making and transportation process is time-consuming, which not only slows down construction but also interferes with construction. In addition, ice making requires a large amount of water resources, and the added chemicals and wastewater from melting ice can also pollute the environment.

[0047] This embodiment also provides a method for rapid cooling of the excavation face of a high-temperature tunnel, the steps of which are as follows:

[0048] (1) During the process of excavating and removing muck at the high-temperature tunnel excavation face to complete the anchor bolting and shotcreting, the rock temperature and air pressure before cooling are collected by the integrated monitoring and transmission system 14, and the characteristics of oxygen, carbon dioxide, dust concentration and other features at the excavation face are monitored in real time.

[0049] (2) Move the ring mounting frame 2 and the trolley to the excavation face, open the pressure regulating valve 7, and at the same time, the liquid CO2 storage car delivers CO2 to the carbon dioxide circulating spray cooling mechanism. By controlling the liquid pump 4, the liquid CO2 in the liquid CO2 storage car is delivered to the nozzle 5 and CO2 is sprayed out. When the pressure and temperature required for freezing are reached in the temporary chamber formed by the automatic roller shutter of the excavation face and the excavation face, the air in the chamber is discharged and the pressure regulating valve is closed.

[0050] (3) When the excavation face is cooled and frozen, the electronic expansion valve 12 controls the amount of gas replenishment through the feedback signal of the pressure sensor, and the liquid CO2 storage vehicle delivers CO2 to the carbon dioxide circulating spray cooling mechanism; the carbon dioxide circulating spray cooling mechanism forms a closed cooling circuit for the CO2 working medium; the CO2 liquid in the CO2 gas-liquid separator in the carbon dioxide circulating spray cooling mechanism is transferred to the nozzle 5 through the liquid pump 4, and a large number of jets containing small-sized droplets are generated by spraying to evenly cover the excavation face and achieve the freezing effect;

[0051] (4) The appropriate pressure and temperature in the temporary chamber formed by the automatic roller shutter and the excavation face can be integrated with the nozzle flow to form a carbon dioxide flow field with uniform horizontal direction and longitudinal temperature gradient. The above low temperature flow field is used to form a freezing mode of pre-cooling and then freezing the object to be frozen, thereby making full use of the cooling capacity of carbon dioxide in the freezing chamber temporarily formed by the roller shutter and the excavation face.

[0052] (5) After spraying continuously for 30 minutes, the carbon dioxide gas that has expanded and vaporized after cooling is drawn through the exhaust gas recovery device 8, and then recompressed and cooled by the on-board machine and transported back to the carbon dioxide circulation spray cooling mechanism, thereby realizing circulation spraying.

[0053] (6) After the spraying and freezing is completed, stop the carbon dioxide circulating spraying and cooling mechanism, close the nozzle regulating valve, stop the exhaust gas recovery device 8, open the pressure regulating valve 7, and discharge the remaining CO2; determine the temperature drop effect according to the data of the integrated monitoring and transmission module, and use the fan and duct control system to ventilate the excavation face; check the environmental parameters of the excavation face, remove the equipment, and carry out subsequent excavation and drilling construction.

[0054] In this embodiment, CO2 can be obtained from byproducts of the process, from high-purity natural gas, or by collecting industrial and tunnel waste gas and pressing it into liquid CO2 using cryogenic equipment, which has the advantage of turning waste into treasure.

[0055] When liquid CO2 is used for cooling, it directly contacts the high-temperature rock face for cooling. In contrast, traditional mechanical refrigeration involves heat transfer to the air medium via a heat exchanger, followed by cooling by cold air, resulting in significant heat loss. The liquid CO2 circulating spray cooling system sprays liquid CO2 onto the high-temperature excavation face, fully utilizing the high latent heat of vaporization and chemical stability of liquid CO2 to rapidly cool the rock mass in a short time. This significantly reduces the time it takes for liquid CO2 to seep out from pores and fissures. Compared to traditional mechanical cooling or freezing (ventilation, ice walls), liquid CO2 cooling can effectively improve production progress.

[0056] This embodiment is designed for underground engineering projects such as high-temperature hydraulic engineering, transportation, and mining, especially for ultra-long and ultra-high-temperature tunnels such as the Sichuan-Tibet Railway and Yunnan-Tibet Railway that traverse plate tectonics zones, where the construction period is critical and the need to protect the fragile geological and ecological environment of the plateau is paramount. It features functions such as rapid dust removal and rapid stabilization of the excavation face, and is a safe, effective, simple, time-saving, efficient, and environmentally friendly new technology.

[0057] For tunnels in high-temperature, water-rich, and weak surrounding rock, the required heat for freezing of the water-rich soft rock can be accurately calculated, and the freezing temperature can be precisely controlled to achieve rapid cooling or even freezing of the excavation face, thereby stabilizing the soft rock excavation face.

[0058] This invention occupies little space and is easy to maintain. The liquid CO2 cooling system mainly relies on the ring-shaped mounting frame in front of the excavation platform. It consists of a temporary freezing chamber formed by a small-footprint retractable automatic roller shutter in front of the excavation platform. It does not occupy the construction cycle time, and the corresponding mechanical equipment is movable. Therefore, maintenance, cleaning, and defrosting are convenient.

[0059] This invention allows for the recycling of refrigerant during the spray cooling process, saving spray cooling costs while also conserving water and electricity resources. It is economical, safe, effective, and easy to operate, and can also effectively protect the plateau ecological environment.

[0060] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that 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 rapid cooling of the excavation face of a high-temperature tunnel, characterized in that, A rapid cooling system for the high-temperature tunnel excavation face is employed. The system includes a carbon dioxide circulating spray cooling mechanism and an annular mounting frame mounted on the carbon dioxide circulating spray cooling mechanism near the excavation face. Multiple nozzles are evenly distributed on the annular mounting frame. The carbon dioxide circulating spray cooling mechanism includes a liquid CO2 storage vehicle, a gas delivery pipe connected to the liquid CO2 storage vehicle, and a waste gas recovery pipe. The outlet of the gas delivery pipe is connected to the nozzles, and the inlet of the waste gas recovery pipe is located on the annular mounting frame. The method includes the following steps: (1) During the process of excavating and removing muck at the high-temperature tunnel excavation face to complete the anchor bolting and shotcreting, the rock temperature and air pressure before cooling are collected through the integrated monitoring and transmission system, and the oxygen, carbon dioxide and dust concentration characteristics of the excavation face are monitored in real time. (2) Move the ring mounting frame and liquid CO2 storage car to the excavation face, open the pressure regulating valve, and at the same time, the liquid CO2 storage car delivers CO2 to the carbon dioxide circulating spray cooling mechanism. By controlling the liquid pump, the CO2 liquid in the CO2 storage car is delivered to the nozzle and sprayed out. When the pressure and temperature required for freezing are reached in the temporary chamber formed by the automatic roller shutter of the excavation face and the excavation face, the air in the chamber is discharged and the pressure regulating valve is closed. (3) When the excavation face is cooled and frozen, the electronic expansion valve controls the amount of gas replenishment through the feedback signal of the pressure sensor, and the liquid CO2 storage vehicle delivers CO2 to the carbon dioxide circulating spray cooling mechanism; the carbon dioxide circulating spray cooling mechanism forms a closed cooling circuit for the CO2 working medium; the CO2 liquid in the CO2 gas-liquid separator in the carbon dioxide circulating spray cooling mechanism is transferred to the nozzle through the liquid pump, and a large number of jets containing small-sized droplets are generated by spraying to evenly cover the excavation face and achieve the freezing effect; (4) The appropriate pressure and temperature in the temporary chamber formed by the automatic roller shutter and the excavation face can be integrated with the nozzle flow to form a CO2 flow field with uniform transverse direction and longitudinal temperature gradient. The above CO2 flow field is used to form a freezing mode of pre-cooling and then freezing the object to be frozen, thereby making full use of the cooling capacity of carbon dioxide in the freezing chamber temporarily formed by the automatic roller shutter and the excavation face. (5) After spraying continuously for 30 minutes, the CO2 gas that has expanded and vaporized after cooling is drawn in by the CO2 gas recovery device, and then recompressed and cooled by the vehicle-mounted machine and sent back to the carbon dioxide circulation spray cooling mechanism, thereby realizing circulation spraying. (6) After the spraying and freezing is completed, stop the carbon dioxide circulating spraying and cooling mechanism, close the nozzle regulating valve, stop the CO2 gas recovery device, open the pressure regulating valve, and discharge the remaining carbon dioxide; determine the temperature drop effect according to the data of the integrated monitoring and transmission module, and use the fan and duct control system to ventilate the excavation face; check the environmental parameters of the excavation face, remove the equipment, and carry out subsequent excavation and drilling construction.

2. The rapid cooling method for high-temperature tunnel excavation faces according to claim 1, characterized in that, The angle between the nozzle and the excavation face is in the range of 30°-90°.

3. The method for rapid cooling of high-temperature tunnel excavation faces according to claim 1 or 2, characterized in that, The gas delivery pipeline is connected to the liquid CO2 storage vehicle via a pipe with a flanged end. The pipeline is equipped with a delivery pump, an electronic expansion valve, a pressure regulating valve, a CO2 gas-liquid separator, and a compressor, which are connected to the liquid CO2 storage vehicle, in sequence according to the gas outlet direction. The compressor is connected to the nozzle.

4. The rapid cooling method for high-temperature tunnel excavation faces according to claim 3, characterized in that, The waste gas recovery pipeline is equipped with a CO2 gas-liquid separator, a CO2 gas recovery device, and a throttle valve connected to the annular mounting frame in sequence according to the waste gas recovery direction. The throttle valve is connected to the liquid CO2 storage vehicle.

5. The rapid cooling method for high-temperature tunnel excavation faces according to claim 4, characterized in that, An automatic roller shutter is also installed on the ring-shaped mounting frame.

6. The rapid cooling method for high-temperature tunnel excavation faces according to claim 5, characterized in that, After the automatic roller shutter quickly falls and unfolds, a comprehensive monitoring and transmission system is installed in the relatively enclosed cooling space formed with the excavation face. The comprehensive monitoring and transmission system is used to collect the temperature and pressure of the surrounding rock at different locations of the excavation face and in the enclosed cooling space, and to monitor the oxygen, carbon dioxide, and dust concentrations at the excavation face in real time.

7. The rapid cooling method for high-temperature tunnel excavation faces according to claim 5 or 6, characterized in that, The carbon dioxide circulating spray cooling mechanism also includes a control module that integrates a pressure sensor. The control module is used for automatic curtain retraction and extension, automatic adjustment of nozzle angle and flow rate, liquid CO2 pumping and pressurization, spray control switch, data acquisition and control, and data analysis.

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