A device for rapid freezing of shield tunneling butt joint in ground with liquid nitrogen and implementation method

Abstract

The application provides a kind of quick freezing rescue device for liquid nitrogen butt joint in shield ground, relate to the field of shield, reduce construction preparation time, realize quick water sealing and leakage stopping, including freezing tool, freezing tool side is connected with liquid nitrogen tank through liquid supply pipe, pressure control valve is set at the outlet of liquid nitrogen tank to control liquid nitrogen pressure at the outlet of liquid nitrogen tank and keep constant, the other side of freezing tool is connected with exhaust pipe, and is installed in closed exhaust pipeline, freezing tool includes two structural types of first freezing tool and second freezing tool, first freezing tool and second freezing tool share external sleeve, first freezing tool further includes liquid nitrogen inlet and direct exhaust part, second freezing tool further includes liquid nitrogen inlet and circulating exhaust part, external sleeve includes drill bit, drill bit is connected with flower tube type stainless steel seamless sleeve, a plurality of holes are formed on the front side of flower tube type stainless steel seamless sleeve, welding baffle is arranged on flower tube type stainless steel seamless sleeve, inlet and outlet valve and sleeve flange plate.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel engineering technology, specifically a rapid freezing emergency device for liquid nitrogen during underground docking of shield tunnels. Background Technology

[0002] In recent years, with economic and social development, my country's shield tunneling engineering has been continuously developing towards "longer, larger, deeper, more difficult, and more dangerous" directions. Faced with ultra-long distances, ultra-large diameters, complex geology, and high water pressure, the excavation distance of a single shield machine is limited, making it impossible to complete the excavation task independently. Therefore, the scheme of two shield machines excavating in opposite directions to complete the underground docking has become a key research focus.

[0003] There are two common methods for underground tunnel boring machine (TBM) docking: civil engineering and mechanical docking. Currently, mechanical docking requires specialized design for the TBM, demands high precision, and involves expensive equipment. The most common method is civil engineering docking, where the TBM is connected using civil engineering techniques after it has advanced a certain distance. Appropriate reinforcement and water-stopping measures are selected based on the geological conditions, such as grouting, freezing reinforcement, or a combination of both. Only after meeting the strength and water-sealing requirements can the cutterhead of the docking section be removed, the soil excavated, and the lining constructed.

[0004] In underwater tunnels containing abundant groundwater, freezing is often considered as the primary reinforcement and water-stopping method. However, if monitoring is inadequate during the development of the frozen wall, weak points may appear at the frozen junction. After excavation, these weak points can easily form seepage channels, posing a risk of water and sand inrush. Once leakage occurs, the seepage channels will continuously expand due to energy exchange, significantly increasing the risk. Therefore, after water seepage occurs, immediate plugging measures are necessary to seal the leak, minimizing disturbance to the frozen wall and achieving rapid sealing.

[0005] Based on the above considerations, rapid freezing with liquid nitrogen has become a feasible emergency solution. Its principle is to utilize the direct vaporization of liquid nitrogen as a cold source, achieving heat exchange with the surrounding medium, causing water to freeze rapidly, thus achieving rapid freezing. This method has the advantages of system simplicity, fast freezing speed, and no pollution. Currently, the application of liquid nitrogen freezing in tunnels is becoming increasingly widespread, such as in actual projects like shield tunneling entry and exit, shield opening, and secondary water sealing of tunnel working shafts. Currently, liquid nitrogen freezing for leak sealing and emergency repairs mainly involves drilling a certain number of freezing holes at or around the leak point. This allows heat exchange to complete within a certain time, forming a freezing curtain and an ice plug at the leak point, thus achieving sealing. Compared to directly sealing within the leak channel, the entire emergency repair process is longer, and the drilling process may expand the seepage channel and increase the leak area, which undoubtedly increases the risk level during the emergency repair process.

[0006] In summary, firstly, liquid nitrogen freezing is only used when leakage is under control to a certain extent, thus meeting subsequent construction requirements. Currently, using liquid nitrogen freezing immediately upon discovering a leak is not a mature construction method. Secondly, the preliminary preparation time during construction is relatively long, requiring drilling around the leak point to lay freezing pipes and install circulation pipelines, among other procedures. However, in cases of leakage from a frozen wall, large-scale drilling operations cause significant disturbance to the frozen wall, undoubtedly increasing the risks during the drilling process. Summary of the Invention

[0007] The purpose of this invention is to address the aforementioned problems and shortcomings of the existing technology by designing a rapid liquid nitrogen freezing emergency device for shield tunneling underground docking, which reduces construction preparation time, enhances timeliness, reduces the impact on the frozen wall, and achieves rapid water sealing and leak plugging.

[0008] A rapid freezing and emergency repair device using liquid nitrogen for underground docking of tunnel boring machines.

[0009] The device includes a refrigeration fixture, one side of which is connected to a liquid nitrogen tank via a liquid supply pipe. A pressure control valve is installed at the outlet of the liquid nitrogen tank to control and maintain a constant liquid nitrogen pressure. The other side of the refrigeration fixture is connected to an exhaust pipe and installed within a sealed exhaust duct.

[0010] The cryogenic fixture includes two structural types: a first cryogenic fixture and a second cryogenic fixture. The first and second cryogenic fixtures share an external sleeve. The first cryogenic fixture also includes a liquid nitrogen inlet and a direct exhaust section, while the second cryogenic fixture also includes a liquid nitrogen inlet and a circulating exhaust section.

[0011] The outer casing includes a drill bit connected to a perforated stainless steel seamless casing. The perforated stainless steel seamless casing has several holes on its front side. The perforated stainless steel seamless casing is provided with a welding baffle for welding to the shield machine cutting ring at the cutterhead docking point. The perforated stainless steel seamless casing is also provided with an inlet / outlet valve and a casing flange at its end.

[0012] Furthermore, the liquid nitrogen inlet and exhaust section includes a first liquid inlet pipe, a first liquid inlet flange connected to the sleeve flange, a first liquid supply pipe connection flange for connecting to the liquid supply pipe, a liquid inlet control ball valve, a first exhaust valve and a first exhaust pressure gauge, and a reinforcing base connected to the end of the first liquid inlet pipe.

[0013] Preferably, the formation water pressure P0 and the maximum design pressure P of the perforated stainless steel seamless casing 16 are... m The pipe wall thickness δ is designed to meet the following conditions:

[0014] P0=γ0h*10 -3

[0015] P m =2P0

[0016]

[0017] l=h q +l0+l f

[0018] l0 = l h +l s =0.4D e +0.1D e =0.5D e

[0019] l f =2D e

[0020] In the formula, P0 represents formation water pressure, γ0 represents water unit weight, h represents water depth, and P m δ represents the maximum design pressure that the perforated stainless steel seamless sleeve can withstand, and D represents the wall thickness of the perforated stainless steel seamless sleeve. e The outer diameter of the perforated stainless steel seamless sleeve is represented by [σ], the allowable stress of the material at the design temperature is represented by [σ], and the length of the perforated stainless steel seamless sleeve is represented by h. q The height of the shield tunneling machine's cutting ring is indicated by l0, and the length of the casing inserted into the soil is indicated by l. h Indicates the opening length of the perforated stainless steel seamless sleeve, l s This indicates the distance of the seamless stainless steel sleeve in the soil layer, l f This indicates the distance from the sleeve flange to the welding baffle.

[0021] Preferably, the welding baffle 17 meets the following conditions:

[0022] a = 1.1L q

[0023] b = nπr / 180

[0024] d = 0.005

[0025] m=ρabd≤10

[0026] In the formula, 'a' represents the length of the welding baffle, and 'L' represents the length of the welding baffle. q The values ​​represent the spacing between the cut rings of the tunnel boring machine, b represents the width, n represents the center angle, r represents the radius of the cut ring, d represents the thickness, m represents the weight, and ρ represents the density.

[0027] Furthermore, the liquid nitrogen inlet and circulating exhaust section includes a second liquid inlet pipe, a sealed refrigeration pipe inside the second liquid inlet pipe, a second liquid inlet pipe flange, a second exhaust pressure gauge, a second exhaust valve, a liquid inlet valve, and a connecting flange for the second liquid supply pipe.

[0028] Furthermore, preferably, the sealed refrigeration tube is designed to meet the following conditions to satisfy the exhaust pressure:

[0029] D t =D e -2δ-3

[0030] P t =1.8P0

[0031]

[0032] l t =l-l'+l w =l-10+3D e

[0033] In the formula, D t P represents the outer diameter of the sealed refrigeration tube. t Indicates the design pressure inside the sealed refrigeration tube, l t l' indicates the length of the sealed refrigeration tube, and l' indicates the distance between the sealed refrigeration tube and the perforated stainless steel seamless sleeve. w This indicates the outer length of the second inlet pipe flange.

[0034] Preferably, the second inlet pipe meets the following conditions:

[0035] D j =D t / 2

[0036] δ j =δ t

[0037] l j =l t

[0038] D c =1.5D j

[0039] In the formula, D j Indicates the outer diameter of the second inlet pipe, δ j Indicates the thickness of the second inlet pipe, l j D represents the length of the second inlet pipe. c This indicates the diameter of the second air outlet valve.

[0040] Preferably, the diameter of the drill bit tail is larger than the diameter of the perforated stainless steel seamless casing. At the same time, a plastic film is wrapped around the holes of the perforated stainless steel seamless casing to ensure that water and sand do not flow into the freezing fixture through the holes during drilling into the soil layer, and to prevent liquid nitrogen from freezing the water inside the freezing fixture and affecting the rapid freezing effect.

[0041] Preferably, the liquid supply pipe is connected to the liquid nitrogen tank via a liquid nitrogen tank flange, which facilitates quick replacement of the liquid nitrogen tank after the liquid nitrogen is used up. A sealing ring is provided between the liquid nitrogen tank flanges to ensure a sealed condition.

[0042] Preferably, the liquid supply pipe is a flexible tube, and the outside is wrapped with rubber and plastic sponge insulation material to reduce the loss of cold energy during the transmission of liquid nitrogen in the liquid supply pipe.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] The purpose of this invention is to address the aforementioned problems and shortcomings of the existing technology by designing a rapid liquid nitrogen freezing emergency device for shield tunneling underground docking, which reduces construction preparation time, enhances timeliness, reduces the impact on the frozen wall, and achieves rapid water sealing and leak plugging.

[0045] 1. This invention is designed for the special working condition of water sealing after the cutterhead of the shield tunneling machine is cut. Combined with the excavation work space, it can realize operation in a confined space.

[0046] 2. In order to quickly seal the water and sand seepage channels, the present invention initially adopts a perforated tube-type freezing fixture with a membrane at the front end for waterproof protection. After liquid nitrogen enters the fixture, the membrane is ruptured under pressure, and the liquid nitrogen flows into the seepage channel, directly exchanging cold energy with the water to achieve rapid freezing.

[0047] 3. After the channel of this invention is frozen and sealed, a large portion of the nitrogen gas will diffuse into the tunnel along the tooling. To ensure the safety of the workers, in addition to increasing the ventilation at the cutterhead, a detachable matching circulation pipe is installed on the device. That is, after the water stop sealing, the front-end sealing circulation freezing pipe is replaced inside the original freezing tooling, and a liquid nitrogen exhaust port is added, connected to an external pipeline, and directly discharged into the natural environment to solve the nitrogen diffusion problem. After the cutterhead docking point meets the construction requirements, the circulation pipeline is removed, leaving the perforated stainless steel seamless sleeve in the frozen wall. The remaining part is cut off along the outer edge of the baffle (the side of the tunnel boring machine facing inward), and then quick-drying cement is injected into the tail opening for rapid sealing. A steel plate is tightly attached to the flange at the tail end of the sleeve and welded to the structural support at the cutterhead to achieve sealing and a stable connection with the structure. Attached Figure Description

[0048] Figure 1This is a structural diagram of a liquid nitrogen rapid freezing emergency device for shield tunneling underground docking designed according to the present invention;

[0049] Figure 2 This is a schematic diagram of the first freezing fixture 7-1 of the present invention;

[0050] Figure 3 This is a schematic diagram of the second refrigeration fixture 7-2 of the present invention;

[0051] Figure 4 This is a schematic diagram of the shield machine cutting ring position at the joint between the welding baffle and the cutterhead of the first refrigeration fixture 7-1 of the present invention;

[0052] Figure 5 This is a partially enlarged schematic diagram of the second liquid inlet pipe of the second refrigeration fixture 7-2 of the present invention.

[0053] 1-Frozen wall, 2-Seepage channel, 3-Shield shell steel plate of tunnel boring machine, 4-Screwing ring of tunnel boring machine, 5-Sealed exhaust pipe, 6-Exhaust fan, 7-Refrigeration fixture, 8-Impact hammer, 9-Liquid nitrogen tank, 10-Supply pipe, 11-Liquid nitrogen tank flange, 12-Pressure control valve, 13-Exhaust pipe, 14-Mortar, 15-Drill bit, 16-Sealed stainless steel seamless sleeve, 17-Welded baffle, 18-Inlet / outlet valve, 19-Sleeve flange, 20-First inlet pipe, 2 1-First inlet pipe flange, 22-First inlet valve, 23-First supply pipe connecting flange, 24-Reinforced base, 25-First vent valve, 26-First exhaust pressure gauge, 27-Second inlet pipe, 28-Sealed refrigeration pipe, 29-Second inlet pipe flange, 30-Second exhaust pressure gauge, 31-Second vent valve, 32-Second inlet valve, 33-Second supply pipe connecting flange, 7-1-First refrigeration fixture, 7-2-Second refrigeration fixture. Detailed Implementation

[0054] The following description, in conjunction with the accompanying drawings and specific implementation methods, provides a more detailed explanation of the liquid nitrogen rapid freezing emergency device for underground docking of shield tunnels according to the present invention.

[0055] This invention provides a liquid nitrogen rapid freezing emergency device for shield tunneling underground docking and a construction method that utilizes the rapid freezing properties of liquid nitrogen to quickly seal inrushing water and sand.

[0056] First, this device and method can quickly seal seepage channels without the need for additional drilling, minimizing the impact and damage to the existing frozen wall 1. Furthermore, the first stage employs a perforated tube-type cryogenic fixture, enabling direct energy absorption and conversion of liquid nitrogen for rapid sealing of water and sand.

[0057] Secondly, this device uses replaceable refrigeration fixtures, which can achieve internal circulation after replacement, thus solving the nitrogen emission problem of perforated tube refrigeration fixtures, reducing air pollution in the tunnel, and ensuring the safety of personnel.

[0058] Example 1

[0059] like Figure 1 As shown, this invention provides a rapid liquid nitrogen freezing emergency device for underground docking of a tunnel boring machine (TBM). The device is installed within a seepage channel 2 in the frozen wall 1. This seepage channel 2 is located outside the shield shell steel plate 3 and the TBM cutting ring 4, and consists of a freezing fixture 7, an impact hammer 8, a liquid nitrogen tank 9, a liquid supply pipe 10, an exhaust pipe 13, a sealed exhaust duct 5 leading to the outside, and an exhaust fan 6. The sealed exhaust duct 5 contains an exhaust fan 6. The liquid nitrogen tank 9 is placed on the cutterhead and mortar 14 to be excavated, serving as the base for the liquid nitrogen tank 9. The freezing fixture 7 is detachable and replaceable, and includes a first freezing fixture 7-1 (…). Figure 2 ) and the second refrigeration unit 7-2 ( Figure 3 Two structural types are available. The liquid supply pipe 10 is a vacuum hose, with both its inner and outer layers made of special high-quality stainless steel metal hoses. The interlayer uses multiple layers of insulation material with low thermal conductivity. In addition, it is wrapped with rubber and plastic sponge insulation material to reduce the loss of cold energy during the transfer of liquid nitrogen in the liquid supply pipe 10.

[0060] The liquid nitrogen tank 9 is a liftable, movable roller type, allowing operators to easily move the tank. A pressure control valve 12 is installed at the outlet to control and maintain a constant liquid nitrogen pressure at the outlet of the liquid nitrogen tank 9. The supply pipe 10 is connected to the liquid nitrogen tank 9 via a liquid nitrogen tank flange 11, allowing for quick replacement of the liquid nitrogen tank 9 when it is depleted. The supply pipe 10 is also flanged to the cryogenic fixture 7, with sealing rings installed in the center of each flange to ensure a tight seal.

[0061] like Figure 2As shown in Figure a, the first cryogenic fixture 7-1 is divided into two parts. The first part is the outer casing, which consists of a drill bit 15, a perforated stainless steel seamless casing 16, a welded baffle 17, inlet / outlet valves 18, and a casing flange 19. The perforated stainless steel seamless casing 16 has several holes on its front side. The diameter of the drill bit 15's tail is slightly larger than the diameter of the perforated stainless steel seamless casing 16. Before implementation, plastic film is wrapped around the holes on the perforated stainless steel seamless casing 16, and the sides are secured with tape. The purpose is to ensure that water and sand do not flow into the cryogenic fixture 7 through the holes during drilling into the seepage channel 2, preventing liquid nitrogen from freezing water inside the cryogenic fixture 7 and affecting the rapid freezing effect. The second part consists of a liquid nitrogen inlet and a direct exhaust section, which are respectively composed of a first liquid inlet pipe 20, a first liquid inlet pipe flange 21, a first liquid inlet valve 22, a first liquid supply pipe connecting flange 23 for connecting to the liquid supply pipe 10, a reinforcing base 24, a first exhaust port valve 25, and a first exhaust pressure gauge 26. Figure 2 b is assembled from two parts by bolting together the sleeve flange 19 and the first inlet pipe flange 21.

[0062] At this time, the water pressure P0 and the maximum design pressure P of the 16-inch seamless stainless steel perforated sleeve are... m The design of the pipe wall thickness δ should meet the following conditions:

[0063] P0=γ0h*10 -3

[0064] P m =2P0

[0065]

[0066] l=h q +l0+l f

[0067] l0 = l h +l s =0.4D e +0.1D e =0.SD e

[0068] l f =2D e

[0069] In the formula,

[0070] P0 represents the formation water pressure, in MPa;

[0071] γ0 represents the unit weight of water, kN / m3;

[0072] h represents water depth, in meters;

[0073] P m Indicates the maximum design pressure, in MPa;

[0074] δ represents the wall thickness of the seamless stainless steel sleeve, in mm;

[0075] D e Indicates the outer diameter of the perforated stainless steel seamless sleeve, in mm;

[0076] [σ] represents the allowable stress of the material at the design temperature;

[0077] l represents the pipe length, in mm;

[0078] h q Indicates the height of the tunnel boring machine's cutting ring, in mm;

[0079] l0 represents the insertion length of the perforated stainless steel seamless sleeve into the soil, in mm;

[0080] l h Indicates the opening length of the perforated stainless steel seamless sleeve, in mm;

[0081] l s Indicates the distance of the perforated stainless steel seamless sleeve in the soil layer, in mm;

[0082] l f This indicates the distance from the sleeve flange to the welding baffle, in mm;

[0083] like Figure 4 As shown, the shield machine cutting ring 4 at the joint between the welding baffle 17 and the cutterhead is welded. To ensure better fit with the shield machine cutting ring 4 in the width direction and for ease of manual operation, it is recommended that the weight be less than 10kg. Its dimensions should meet the following conditions:

[0084] a = 1.1L q

[0085] b = nπr / 180

[0086] d = 0.005

[0087] m=ρabd≤10

[0088] In the formula,

[0089] 'a' represents the length of the welding baffle, in meters.

[0090] L q Indicates the spacing between the cut rings of the tunnel boring machine, in meters (m).

[0091] b represents the width, in meters;

[0092] n represents the central angle, in degrees;

[0093] r represents the radius of the cut ring, in meters;

[0094] d represents thickness, in meters;

[0095] m represents weight, in kg;

[0096] ρ represents density, in kg / m³;

[0097] Figure 3 a is the refrigeration fixture 7-2, whose second part has a changed structure and has been disassembled and adjusted to be a liquid nitrogen inlet and circulation exhaust section, which consists of a sealed refrigeration pipe 28, a second liquid inlet pipe 27, a second liquid inlet pipe flange 29, a second exhaust pressure gauge 30, a second exhaust valve 31, a second liquid inlet valve 32, and a second liquid supply pipe connecting flange 33. Figure 3 b is assembled from two parts by bolting together the sleeve flange 19 and the second inlet pipe flange 29.

[0098] The sealed refrigeration tube 28 needs to be installed in the perforated stainless steel seamless sleeve 16, and in order to meet the exhaust pressure requirements, the following conditions must be met:

[0099] D t =D e -2δ-3

[0100] P t =1.8P0

[0101]

[0102] l t =l-l'+l w =l-10+3D e

[0103] In the formula,

[0104] D t Indicates the outer diameter of the sealed refrigeration tube, in mm;

[0105] P t Indicates the design pressure inside the sealed refrigeration tube, in MPa;

[0106] l t Indicates the length of the sealed freezer tube, in mm;

[0107] l' indicates the distance between the sealed refrigeration tube and the perforated stainless steel seamless sleeve, in mm;

[0108] l w Indicates the outer length of the second inlet pipe flange, in mm;

[0109] In addition, such as Figure 5The total length of the second liquid inlet pipe 27 is equal to the length of the sealed refrigeration pipe 28, and the insertion distance is e; the diameter of the second vent valve 31 is 1.5D. j And satisfy the following conditions:

[0110] D j =D t / 2

[0111] δ j =δ t

[0112] l j =l t

[0113] D c =1.5D j

[0114] In the formula,

[0115] D j Indicates the outer diameter of the second inlet pipe, in mm;

[0116] δ j Indicates the thickness of the second inlet pipe, in mm;

[0117] l j Indicates the length of the second inlet pipe, in mm;

[0118] D c Indicates the diameter of the second air outlet valve, in mm;

[0119] Example 2

[0120] The present invention also provides a method for implementing a liquid nitrogen rapid freezing emergency device for shield tunneling underground docking.

[0121] First, before construction, the first liquid supply pipe flange 23 of the refrigeration fixture 7 was connected to the liquid nitrogen tank flange 11 via the liquid supply pipe 10. The first vent valve 25 was connected to the exhaust pipe 13 and installed within the sealed exhaust duct 5. Furthermore, all valves in the refrigeration fixture 7 were kept closed, and the impact hammer 8, sealed exhaust duct 5, exhaust fan 6, and other devices were tested to ensure continuity, timeliness, and safety during the emergency. In addition, all necessary materials, supplies, and personnel were prepared.

[0122] If seepage channels 2 are formed within the frozen wall 1 after on-site cutting and excavation, causing leakage, this method is divided into two stages. The first part is the emergency water sealing stage, and this stage should minimize the sealing time to prevent the seepage channels 2 from expanding and increasing, leading to large-scale melting of the frozen wall 1, water and sand inrush, or even collapse. Figure 1 and Figure 2As shown, the impact hammer 8 is used to impact the tail end reinforcement base 24 of the first freezing fixture 7-1, and the front drill bit 15 is used to drill into the seepage channel 2. The drilling distance should be such that the welding baffle 17 can be welded to the positions of the shield machine cutting rings 4 on both sides. After the welding is firm, the liquid nitrogen tank pressure control valve 12 is opened to start liquid supply, and then the first liquid inlet valve 22 is opened. Liquid nitrogen enters the freezing fixture under pressure. At this time, the pressure of the first exhaust pressure gauge 26 increases. After the liquid nitrogen breaks through the membrane and is released into the soil, the pressure drops instantly. At this time, the first vent valve 25 is opened to exhaust the liquid nitrogen. After liquid nitrogen enters the soil layer, it instantly absorbs heat and changes from a liquid state to a gaseous state, rapidly cooling and freezing the water and sand. During this process, the nitrogen gas flows in three directions: one part permeates into the interior of the freezing wall 1 along the seepage channel 2, i.e., away from the inside of the tunnel boring machine; of the other two parts, one part enters the tunnel boring machine through the gap between the freezing fixture 7 and the seepage channel 2; and the other part flows out through the first outlet valve 25 inside the first freezing fixture 7-1. At this time, the two parts of gas are discharged to the outside through the sealed exhaust pipe 5 under the action of the exhaust fan 6.

[0123] like Figure 3 After all water and sand have stopped seeping in, close the pressure control valve 12. Replace the components of the refrigeration fixture. The first part of the outer sleeve of the refrigeration fixture remains fixed in the seepage channel 2 due to water consolidation. Remove the second part and replace it with a sealed internal circulation pipe 7-2. Connect the liquid supply pipe 10 to the second liquid supply pipe flange 33, and connect the second vent valve 31 to the vent pipe 13. Since there is a gap between the replaced sealed sleeve and the original outer sleeve, to achieve good refrigeration, inject low-temperature heat transfer oil into the gap through the inlet of one of the inlet / outlet valves 18. Open the outlet of the inlet / outlet valve 18 to facilitate the discharge of gas from the pipe. After the low-temperature heat transfer oil flows out of the outlet of the inlet / outlet valve 18, close the inlet / outlet valve 18. The low-temperature heat transfer oil is characterized by low viscosity at extremely low temperatures, good cold transfer efficiency, and protection of the metal coils in contact with it from corrosion.

[0124] Subsequently, pressure control valve 12, second liquid inlet valve 32, and second vent valve 31 are opened sequentially for refreezing. During this process, liquid nitrogen does not enter the soil layer; the vaporized nitrogen is discharged through vent valve 31, enabling long-term freezing until the cutterhead of the connecting section is removed and the soil excavation is completed. This prevents air pollution inside the tunnel and better protects personnel safety during subsequent construction.

[0125] After the cutterhead docking point meets the construction requirements, the circulation pipeline is removed, and the seamless stainless steel sleeve 16 is retained in the frozen wall 1. The remaining part is cut off along the outer edge of the welded baffle 17 (the side of the tunnel boring machine facing inward). Then, quick-drying cement is injected into the tail opening for rapid sealing, and a steel plate is tightly attached to the flange at the tail end of the sleeve and welded to the structural support at the cutterhead to achieve sealing and a stable connection with the structure.

[0126] This invention proposes a rapid liquid nitrogen freezing emergency device for underground docking of tunnel boring machines. The above embodiments are only for illustrating the technical concept and features of this invention, and are intended to enable those skilled in the art to understand the content of this invention and implement it accordingly. They should not be construed as limiting the scope of protection of this invention. All equivalent changes or modifications made in accordance with the spirit and essence of this invention should be covered within the scope of protection of this invention.

Claims

1. A rapid freezing and emergency repair device using liquid nitrogen for underground docking of a shield tunnel, characterized in that: The device includes a refrigeration fixture (7), one side of which is connected to a liquid nitrogen tank (9) via a liquid supply pipe (10). A pressure control valve (12) is installed at the outlet of the liquid nitrogen tank (9) to control and maintain a constant liquid nitrogen pressure at the outlet of the liquid nitrogen tank (9). The other side of the refrigeration fixture (7) is connected to an exhaust pipe (13) and installed inside a closed exhaust duct (5). The refrigeration fixture (7) includes two structural types: a first refrigeration fixture (7-1) and a second refrigeration fixture (7-2). The first refrigeration fixture (7-1) and the second refrigeration fixture (7-2) share an external sleeve. The first refrigeration fixture (7-1) also includes a liquid nitrogen inlet and a direct exhaust section, while the second refrigeration fixture (7-2) also includes a liquid nitrogen inlet and a circulating exhaust section. The outer casing includes a drill bit (15), which is connected to a perforated stainless steel seamless casing (16). The perforated stainless steel seamless casing (16) has several holes on its front side. The perforated stainless steel seamless casing (16) is provided with a welding baffle (17) for welding to the shield machine cutting ring (4) at the cutterhead docking point. The perforated stainless steel seamless casing (16) is also provided with an inlet / outlet valve (18) and a casing flange (19) at its end. The liquid nitrogen inlet and exhaust section includes a first liquid inlet pipe (20), a first liquid inlet pipe flange (21) connected to the sleeve flange (19) on the first liquid inlet pipe (20), a first liquid supply pipe connection flange (23) for connecting to the liquid supply pipe (10) on the first liquid inlet pipe (20), a first liquid inlet valve (22), a first exhaust port valve (25) and a first exhaust pressure gauge (26), and a reinforcing base (24) connected to the end of the first liquid inlet pipe (20). The liquid nitrogen inlet and circulating exhaust section includes a second liquid inlet pipe (27), which is installed inside a sealed refrigeration pipe (28). The second liquid inlet pipe (27) is also provided with a second liquid inlet pipe flange (29), a second exhaust pressure gauge (30), a second exhaust port valve (31), a second liquid inlet valve (32), and a second liquid supply pipe connecting flange (33). During the emergency water sealing phase, the first refrigeration fixture (7-1) is frozen. After there is no water or sand leakage, the first refrigeration fixture (7-1) is replaced and the sealed refrigeration pipe (28) is installed in the flower-shaped stainless steel seamless sleeve (16).

2. The rapid freezing and emergency repair device for liquid nitrogen during underground docking of a shield tunnel as described in claim 1, characterized in that: Formation water pressure P0, and the maximum design pressure P of the perforated stainless steel seamless casing (16) m The pipe wall thickness δ is designed to meet the following conditions: ； ； ； ； ； ； In the formula, P0 represents the formation water pressure, MPa; γ0 represents the unit weight of water, kN / m³. 3 h represents water depth, in meters; P m δ represents the maximum design pressure that the perforated stainless steel seamless sleeve can withstand, in MPa; δ represents the wall thickness of the perforated stainless steel seamless sleeve, in mm; D e [σ] represents the outer diameter of the perforated stainless steel seamless sleeve, in mm; [σ] represents the allowable stress of the material at the design temperature, in MPa; l represents the length of the perforated stainless steel seamless sleeve, in mm; h q The height of the shield tunneling machine's cutting ring is indicated in mm; l0 indicates the length of the casing inserted into the soil in mm; h This indicates the opening length of the perforated stainless steel seamless sleeve, in mm; l s This indicates the distance (mm) of the seamless stainless steel sleeve located in the soil layer; l f This indicates the distance from the sleeve flange to the welding baffle, in mm.

3. The rapid freezing and emergency repair device for liquid nitrogen during underground docking of a shield tunnel as described in claim 2, characterized in that: The welding baffle (17) meets the following conditions: ； ； ； ； In the formula, a represents the length of the welding baffle, in meters; L q The following parameters are represented: b (distance between cut-off rings of the tunnel boring machine, m); d (width, m); n (central angle, °); r (radius of the cut-off ring, m); d (thickness, m); m (weight, kg); ρ (density, kg / m³). 3 .

4. The rapid freezing and emergency repair device for liquid nitrogen during underground docking of a shield tunnel as described in claim 3, characterized in that: The sealed refrigeration tube (28) is designed to meet the following conditions to satisfy the exhaust pressure: ； ； ； ； In the formula, Indicates the outer diameter of the sealed refrigeration tube, in mm; Indicates the design pressure inside the sealed refrigeration tube, in MPa; Indicates the length of the sealed freezer tube, in mm; Indicates the distance between the sealed refrigeration tube and the perforated stainless steel seamless sleeve, in mm; This indicates the outer length of the second inlet pipe flange, in mm.

5. The rapid freezing and emergency repair device for liquid nitrogen during underground docking of a shield tunnel as described in claim 4, characterized in that: The second inlet pipe (27) meets the following conditions: ； ； ； ； In the formula, Indicates the outer diameter of the second inlet pipe, in mm; Indicates the thickness of the second inlet pipe, in mm; Indicates the length of the second inlet pipe, in mm; This indicates the diameter of the second air outlet valve, in mm.

6. The rapid freezing and emergency repair device for liquid nitrogen during underground docking of a shield tunnel as described in claim 1, characterized in that: The diameter of the drill bit (15) tail is larger than the diameter of the perforated stainless steel seamless sleeve (16). At the same time, a plastic film is wrapped around the hole of the perforated stainless steel seamless sleeve (16) to ensure that water and sand will not flow into the freezing fixture (7) through the hole during the drilling process, and to prevent liquid nitrogen from freezing the water in the freezing fixture (7) after entering, thus affecting the rapid freezing effect.

7. The rapid freezing and emergency repair device for liquid nitrogen during underground docking of a shield tunnel as described in claim 1, characterized in that: The liquid supply pipe (10) is connected to the liquid nitrogen tank (9) via a liquid nitrogen tank flange (11) to facilitate quick replacement of the liquid nitrogen tank (9) after the liquid nitrogen is used up. A sealing ring is provided between the liquid nitrogen tank flanges (11) to ensure a sealed state.

8. The rapid freezing and emergency repair device for liquid nitrogen during underground docking of a shield tunnel as described in claim 1, characterized in that: The liquid supply pipe (10) is a flexible tube, and the outside is wrapped with rubber and plastic sponge insulation material to reduce the loss of cold energy during the transmission of liquid nitrogen in the liquid supply pipe (10).

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