A shield tunnel lining steel pipe welded joint external protection structure and construction technology

Abstract

The present invention discloses an external combined protection structure and construction process for welds of lining steel pipes in a shield tunnel. A liquid coating is arranged on the outside of welds of two butted lining steel pipes, so that a coating protection structure is formed on the outside of the welds of the lining steel pipes. At the same time, an anode plate with metal activity stronger than that of the lining steel pipe is arranged on the outside of the welds of the two butted lining steel pipes, and a feeder cable is used to connect the lining steel pipe and the anode plate to form a cathodic protection structure of the lining steel pipe, thereby realizing a dual combined anti-corrosion protection structure of "coating + cathodic protection" for the outside of the welds of the lining steel pipes, thereby extending the service life of the steel pipes. At the same time, a specific construction process is adopted to realize external anti-corrosion construction in long-line shield tunnels, narrow construction spaces and harsh construction conditions, thereby reducing the installation cost of the lining steel pipes, improving the reliability of construction, controlling the thickness of the liquid coating and achieving high coating efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of steel pipe installation in a shield tunnel, and specifically relates to an external combined protective structure for welded joints of steel pipes lined in a shield tunnel and a construction process. Background Art

[0002] With the development of domestic economy, the scale of cities is getting bigger and bigger, the amount of water supply and sewage is getting bigger and bigger, and the diameter of pipes required is getting bigger and bigger. Cement pipes are generally used, but cement pipes are heavy, slow to construct, increase the input of manpower and material resources, and the recycling of cement pipes produces construction waste that cannot be reused.

[0003] Therefore, there is a trend of gradually replacing lined steel pipes, such as large drainage pipes. During the construction of water resource allocation projects, when the shield tunnel lined steel pipes are connected, it is not only necessary to transport the lined steel pipes with a weight of 48t, an inner diameter of 4800mm, and a length of 12000mm into the tunnel, but also to weld them in a narrow space. The above problems have been solved with the concerted efforts of many engineers. Generally, shield machines are used for excavation, prefabricated reinforced concrete segments are laid, and drainage boards may be arranged according to different locations. Then the lined steel pipes are driven into the tunnel, welded one by one, and self-compacting concrete is poured into the injection port inside the lined steel pipes.

[0004] However, after solving the above problems, new challenges are faced. After the welding between two adjacent sections of the lining steel pipe is completed, the welding points on the outside are exposed to the outside, which is easy to be corroded, affecting the service life of the pipeline. In addition, the inner diameter of the shield segment is 5400mm, the inner diameter of the steel pipe is 4800mm, the thickness of the steel plate is 22mm~26mm, the height of the stiffening ring is 120mm, the length of each section is 9~12m, the theoretical gap between the outer wall of the steel pipe and the inner wall of the tunnel is 154mm, and the distance between the butt joint of the steel pipe and the nearest air vent is 2~4m. Limited by the space and distance, not only manual operation is impossible, but also conventional equipment cannot reach it. According to the current conventional process, it is impossible to take effective anti-corrosion measures on the outside of the weld of the lining steel pipe.

[0005] At present, there is no external anti-corrosion technology for long shield tunnel lines, narrow construction spaces and harsh construction conditions at home and abroad. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides an external combined protection structure for the weld joints of the lining steel pipes of a shield tunnel, which solves the problem that the external weld joints of the lining steel pipes of the shield tunnel cannot be effectively protected from corrosion.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] A shield tunnel lining steel pipe weld joint external joint protection structure, including two lining steel pipes connected end to end, the lining steel pipes including a steel pipe substrate and an anti-corrosion coating coated on the inner and outer walls of the steel pipe substrate, the two lining steel pipes are welded, and the outer walls of the weld joints of the two lining steel pipes are sleeved with anode plates for anti-corrosion protection of the welds, two sealing strips are provided on the outer edges of the inner walls of the anode plates at both ends, the anode plates are bonded to the outer walls of the lining steel pipes through the two sealing strips to form a filling interval surrounding the outer periphery of the weld, a filling port connected to the filling interval and an exhaust hole for discharging gas in the filling interval are provided on the anode plates, a liquid coating is filled into the filling interval through the filling port to form a coating protection structure, the metal activity of the anode plates is stronger than that of the lining steel pipes, and the lining steel pipes are connected to the anode plates through a feeder cable to form a cathodic protection structure of the lining steel pipe welds.

[0009] As a further improvement of the present invention, the outer wall of the anode plate is provided with an anti-corrosion layer.

[0010] As a further improvement of the present invention, a fastening mechanism for adjusting the tightness of the anode plate is also provided on the outside of the anode plate, and the outer wall of the anode plate is provided with two fastening plates extending outward, and the fastening mechanism is connected to the two fastening plates, and the tightness of the anode plate is adjusted by adjusting the distance between the two fastening plates.

[0011] As a further improvement of the present invention, the fastening mechanism includes a fastening screw passing through two fastening plates, a nut arranged at one end of the fastening screw and a ratchet wrench arranged at the other end of the fastening screw, and the two fastening plates are arranged between the nut and the ratchet wrench.

[0012] As a further improvement of the present invention, the ratchet wrench is connected to a pull rope for pulling the ratchet wrench to rotate, and the pull rope is pulled into the inner lining steel pipe.

[0013] As a further improvement of the present invention, the exhaust hole is covered with a screen, and the aperture of the screen is smaller than the outer diameter of particles of the material in the liquid coating.

[0014] Another object of the present invention is to provide a construction process for an external combined protective structure for the weld of the lining steel pipe of a shield tunnel, and to utilize this process to implement a combined anti-corrosion protection installation structure of "coating + cathodic protection" on the outside of the weld of the lining steel pipe.

[0015] A construction process for an external joint protective structure of a shield tunnel lining steel pipe weld, comprising the following steps:

[0016] Step 1: First, send the first lining steel pipe into the shield tunnel and fix it;

[0017] Step 2: Clean the loose rust on the outer end of the weld before butt jointing;

[0018] Step 3: Install the anode plate on the end of the lining steel pipe to be connected, and install a traction rope on the anode plate for pulling the anode plate to move;

[0019] Step 4: Pre-weld one end of the feeder cable to the inner lining steel pipe to be connected, and weld the other end to the anode plate. This feeder cable plays the role of impressed current;

[0020] Step 5: gradually move the lined steel pipe to be connected closer to the first lined steel pipe for connection. After the ends of the two lined steel pipes reach a certain distance, extend the traction rope pre-arranged in step 3 to the inside of the first lined steel pipe.

[0021] Step 6: Continue to move the inner lining steel pipe to be connected to the first inner lining steel pipe to achieve connection, and perform welding at the connection point of the two inner lining steel pipes;

[0022] Step 7. After welding is completed, check the welding condition. The outer wall of the lining steel pipe extends outward with a limit plate. Pull the anode plate close to the limit plate by the traction rope and use an endoscope or camera to check whether the anode plate has moved into place.

[0023] Step 8, after the anode plate moving position in step 7 is checked to be correct, the anode plate is retracted to reach a set torque, so that the anode plate is attached to the outer wall of the lining steel pipe through two sealing strips to form a material injection area surrounding the outer periphery of the weld;

[0024] Step 9: Use the injection machine to start injecting paint into the injection port through the feed pipe. Stop injecting after the paint fills the injection interval and forms a liquid coating in the injection interval, and then withdraw the feed pipe and auxiliary tools.

[0025] As a further improvement of the present invention, in step nine, before using the injection machine to inject paint into the injection port, check whether the construction environment temperature is suitable for painting. When the construction environment temperature is low, use an electric heating belt to heat the inside of the surrounding pipe for a period of time to make the outside temperature of the inner steel pipe reach the most suitable temperature for the fluidity of the paint before injecting the paint into the injection port.

[0026] As a further improvement of the present invention, in step nine, the method for judging whether the paint fills the filling interval is: using a probe to observe whether the paint flows out evenly from the exhaust hole. If the paint flows out evenly from the exhaust hole, the paint fills the filling interval; otherwise, the paint does not fill the filling interval.

[0027] The beneficial effects of the present invention are as follows: by arranging a liquid coating on the outside of the weld of the two butted lined steel pipes, a coating protection structure is formed on the outside of the weld of the lined steel pipes; at the same time, by arranging an anode plate with metal activity stronger than that of the lined steel pipes on the outside of the weld of the two butted lined steel pipes, a feeder cable is used to connect the lined steel pipes and the anode plate to form a cathodic protection structure of the lined steel pipes, thereby realizing a dual combined anti-corrosion protection structure of "coating + cathodic protection" for the outside of the weld of the lined steel pipes, and extending the service life of the steel pipes; at the same time, by adopting a specific construction process, external anti-corrosion construction can be realized in long-line shield tunnels, narrow construction spaces and harsh construction conditions, so that the installation cost of the lined steel pipes is reduced, the reliability of construction is improved, the thickness of the liquid coating is controllable, the coating efficiency is high, and fewer parts are left in the shield tunnel, which achieves the purpose of resource recycling and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0029] Figure 1 This is a schematic diagram of the installation structure of the injection zone of this embodiment without the coating being injected;

[0030] Figure 2 This is a schematic diagram of the installation structure after the coating is injected into the injection area of ​​this embodiment;

[0031] Figure 3 Schematic diagram of the installation structure of the fastening mechanism of this embodiment;

[0032] Figure 4 Schematic diagram of the installation structure outside the weld in this embodiment;

[0033] Figure 5 Schematic diagram of the installation structure of the screen in this embodiment;

[0034] Figure 6 for Figure 4 Enlarged view of part I. DETAILED DESCRIPTION

[0035] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0036] Example:

[0037] like Figures 1 to 6As shown, this embodiment discloses an external joint protection structure for the weld of the lining steel pipe of a shield tunnel, comprising two lining steel pipes 1 connected end to end, the lining steel pipe 1 comprising a steel pipe substrate 11 and an anti-corrosion coating 12 coated on the inner and outer walls of the steel pipe substrate 11, the two lining steel pipes 1 are welded, and the outer walls of the weld of the two lining steel pipes 1 are sleeved with an anode plate 2 for anti-corrosion protection of the weld, and two sealing strips 3 are provided on the outer edges of the inner walls of the anode plate 2 at both ends, and the anode plate 2 is attached to the outer wall of the lining steel pipe 1 through the two sealing strips 3 to form a material injection zone 4 surrounding the outer periphery of the weld, and the anode plate 2 is provided with a sealing strip 3. The plate 2 is provided with an injection port 5 connected to the injection interval 4 and an exhaust hole 6 for discharging the gas in the injection interval 4. In the present invention, there are two combinations of the injection port 5 and the exhaust hole 6 on the anode plate 2. 1. The injection port 5 is at the bottom and the exhaust hole 6 is at the top. This layout allows the coating to be gradually filled upward from the injection port 5 at the bottom. This layout structure has high requirements for sealing; 2. The injection port 5 is on both sides or in the middle of a certain height from the top of the anode plate 2. In addition to the pressure of the coating's own feed pipe, there will be an external gravity, which makes it easy for the coating to flow downward. A liquid coating 7 is filled into the injection interval 4 through the injection port 5 to form a coating protection structure, the thickness of the liquid coating 7 is ≥1000μm, the metal activity of the anode plate 2 is stronger than the metal activity of the lining steel pipe 1, and the lining steel pipe 1 is connected to the anode plate 2 through the feeder cable 8 to form a cathodic protection structure of the weld of the lining steel pipe 1. In this embodiment, the outer wall of the lining steel pipe 1 is provided with a rib plate 21, and the feeder cable 8 can be welded to the end of the lining steel pipe 1 or the rib plate 21 near the end, both of which have the same technical effect, and the welding of the feeder cable is repaired with liquid coating, and the outer cover is an electrical heat shrink tube for corrosion protection. A liquid coating 7 is arranged outside the weld of two butted lined steel pipes 1, so that a coating protection structure is formed outside the weld of the lined steel pipe 1. At the same time, an anode plate 2 with a metal activity stronger than that of the lined steel pipe 1 is arranged outside the weld of the two butt-jointed lined steel pipes 1, and a feeder cable 8 is used to connect the lined steel pipe 1 and the anode plate 2 to form a cathodic protection structure of the lined steel pipe 1, thereby realizing a dual combined anti-corrosion protection structure of "coating + cathodic protection" for the outside of the weld of the lined steel pipe 1, thereby extending the service life of the steel pipe.

[0038] As a preferred embodiment, in order to provide the anode plate 2 with corresponding anti-corrosion protection, the outer wall of the anode plate 2 is provided with an anti-corrosion layer 9. In this embodiment, the anode plate 2 is a zinc plate with a thickness of 50 μm, and the anti-corrosion layer 9 is a stainless steel plate, and the outer side is an anode plate coating of sintered epoxy powder with a thickness of >150 μm. The metal activity of the zinc plate is stronger than that of the inner-lined steel pipe 1. After the connection is made through the feeder cable 8, when electrochemical corrosion occurs outside the weld, the zinc plate acts as an anode in the electrochemical reaction due to its strong metal activity, and the inner-lined steel pipe 1 acts as a cathode, so that the inner-lined steel pipe 1 will not be corroded, forming a cathodic protection structure.

[0039] As a preferred embodiment, a fastening mechanism for adjusting the tightness of the anode plate 2 is also provided on the outside of the anode plate 2. Two fastening plates 10 extending outward are provided on the outer wall of the anode plate 2. The fastening mechanism is connected to the two fastening plates 10. The tightness of the anode plate 2 is adjusted by adjusting the distance between the two fastening plates 10. The fastening mechanism includes a fastening screw 13 passing through the two fastening plates 10, a nut 14 arranged at one end of the fastening screw 13, and a ratchet wrench 15 arranged at the other end of the fastening screw 13. The two fastening plates 10 are arranged between the nut 14 and the ratchet wrench 15. The ratchet wrench 15 is connected to a pull rope 16 for pulling it to rotate, and the pull rope 16 is pulled into the inner lining steel pipe 1. By pulling the pull rope 16 to rotate the ratchet wrench 15, the stainless steel plate is shortened, and the sealing strip 3 is forced to shrink to achieve a sealing effect. At the same time, the thickness of the liquid coating 7 can be adjusted by adjusting the shortening length of the stainless steel plate.

[0040] As a preferred embodiment, in order to prevent the newly injected coating from being directly discharged from the injection interval 4 through the exhaust hole 6, the exhaust hole 6 is covered with a screen 17, and the aperture of the screen 17 is smaller than the particle outer diameter of the material in the liquid coating 7. The screen 17 is selected with a specific mesh size according to the injected coating. There are several exhaust holes 6 on the anode plate 2, and an exhaust hole 6 is arranged at a certain distance. In this embodiment, the screen 17 is fixed to the anode plate 2 by a pressing plate 22.

[0041] In order to make it more convenient for construction workers to implement the shield tunnel lining steel pipe weld joint external joint protection structure of the present invention, this embodiment also discloses a shield tunnel lining steel pipe weld joint external joint protection structure construction process, including the following steps:

[0042] Step 1: First, send the first lining steel pipe into the shield tunnel for fixing. Before sending the lining steel pipe into the shield tunnel, pre-install auxiliary tools such as endoscopes, cameras and probes on the inner wall of the shield tunnel;

[0043] Step 2: Clean the rust on the outer end of the weld before butt jointing. In addition, in order to make the liquid coating 7 better adhere to the outer wall of the lined steel pipe, the area on the outer wall of the lined steel pipe corresponding to the application of the liquid coating 7 is roughened; the specific treatment method is:

[0044] ① Use high-pressure fresh water to clean oil, dirt and other impurities on the surface of metal structures;

[0045] ② For components with welds, use electric tools or manually to remove weld nodules, burrs, edges and corners and other defects;

[0046] ③ During the surface treatment process, the surface temperature of the component should be more than 3°C higher than the dew point;

[0047] ④ Rust removal should be done by dry spraying (blasting) or high-pressure wet abrasives. The rust removal level should reach Sa.2½ level specified in the current national standard "Surface rust level and rust removal level of steel before painting" GB / T 8923, and the anchor pattern depth should reach 30-100μm. Artificial mechanical rust removal can also reach St3 level standard;

[0048] ⑤ After the surface is sprayed (blasted), clean, dry, oil-free compressed air should be used to remove sand, dust, rust and other fine dust on the surface of the metal structure. The surface dust level should not exceed level 3 specified in GB / T18570.3;

[0049] ⑥ If flash rust occurs locally due to weather reasons, the surface should be re-treated;

[0050] Step 3: Install the anode plate 2 on the end of the inner lining steel pipe to be connected, and install a traction rope 18 on the anode plate 2 for pulling the anode plate 2 to move;

[0051] Step 4: Pre-weld one end of the feeder cable 8 to the inner lining steel pipe to be connected, and weld the other end to the anode plate 2. The feeder cable 8 plays the role of impressed current, so that the protected inner lining steel pipe maintains a negative potential to the ground to achieve a double anti-corrosion protection effect;

[0052] Step 5: gradually move the inner lining steel pipe to be connected closer to the first inner lining steel pipe for connection. After the ends of the two inner lining steel pipes reach a certain distance, extend the traction rope 18 pre-arranged in step 3 to the inside of the first inner lining steel pipe.

[0053] Step 6: Continue to move the inner lining steel pipe to be connected to the first inner lining steel pipe to achieve connection, and perform welding at the connection point of the two inner lining steel pipes;

[0054] Step 7. After welding is completed, check the welding condition. The outer wall of the lining steel pipe extends outward with a limit plate 19. The anode plate 2 is pulled close to the limit plate 19 by the traction rope 18, and an endoscope or camera is used to check whether the anode plate 2 has moved into place; in order to facilitate the end of the traction rope 18 to be tied to the anode plate 2 for connection, a hook 20 is fixed at the end of the anode plate 2. One end of the traction rope 18 is tied and fixed to the hook 20, and the other end is pulled into the lining steel pipe for construction personnel to pull the anode plate 2 to move. In order to enable the anode plate 2 to translate along the central axis, the anode plate 2 is provided with three hooks 20, and the three hooks 20 are evenly arranged around the outer periphery of the anode plate 2. The corresponding three hooks 20 are respectively connected to the three traction ropes 18. When the construction personnel pull the three traction ropes 18 at the same time, the anode plate 2 translates along the central axis.

[0055] Step eight, after the moving position of the anode plate 2 in step seven is checked to be correct, the anode plate 2 is retracted and made to reach the set torque, so that the anode plate 2 is attached to the outer wall of the lining steel pipe through the two sealing strips 3 to form an injection zone 4 surrounding the outer periphery of the weld; the ratchet wrench 15 is pulled by the pull rope 16, thereby driving the fastening screw 13 to rotate to shrink the anode plate 2 and reach the set torque, thereby forming a closed injection zone 4, the height of the injection zone 4, that is, the thickness of the liquid coating 7, can be controlled by setting different torque values;

[0056] Step nine, use the injection machine to start injecting paint into the injection port 5 through the feed pipe. Stop injecting after the paint fills the injection interval 4 and forms a liquid coating 7 in the injection interval 4. Observe the overflow of the paint and judge whether it is full by combining the reduced weight of the injector, and then withdraw the feed pipe and auxiliary tools. The present invention has few parts left in the shield tunnel, and the parts left in the shield tunnel are all treated with corrosion protection to prevent the metal parts from corroding and expanding in volume, affecting the quality of the poured concrete, and also achieving the purpose of resource recycling and cost saving. After a period of time, the liquid paint solidifies into a film in the injection interval 4.

[0057] As a preferred embodiment, in step nine, before using the injection machine to inject the paint into the injection port 5, check whether the construction environment temperature is suitable for painting. The painting temperature should be between 5°C and 45°C, the concrete surface temperature should be 3°C above the dew point, and the relative humidity should be less than 85%. When the construction environment temperature is low, use an electric heating belt to heat the inside of the surrounding pipe for a period of time, so that the outside temperature of the inner steel pipe reaches the most suitable temperature for the fluidity of the paint, and then inject the paint into the injection port 5.

[0058] As a preferred embodiment, in step nine, whether the paint fills the filling interval 4 is judged by using a probe to observe whether the paint flows out evenly from the vent 6. If the paint flows out evenly from the vent 6, the paint fills the filling interval 4; otherwise, the paint does not fill the filling interval 4. Because the paint overflowing from the vent 6 has a delay, it can also be judged by referring to the paint overflowing from the top. When there is paint overflowing from the top, the paint fills the filling interval 4.

[0059] The above description is only a preferred embodiment of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means belongs to the protection scope of the present invention.

Claims

1. An external joint protection structure for welded joints of lining steel pipes in a shield tunnel, comprising two lining steel pipes (1) connected end to end, the lining steel pipes (1) comprising a steel pipe substrate (11) and an anti-corrosion coating (12) coated on the inner and outer walls of the steel pipe substrate (11), the two lining steel pipes (1) being welded, characterized in that: The outer wall of the weld of the two lined steel pipes (1) is sleeved with an anode plate (2) for corrosion protection of the weld. Two sealing strips (3) are provided on the outer edges of the inner walls of the anode plate (2). The anode plate (2) is bonded to the outer wall of the lined steel pipe (1) through the two sealing strips (3) to form a material injection zone (4) surrounding the outer periphery of the weld. The anode plate (2) is provided with a material injection port (5) connected to the material injection zone (4) and an exhaust hole (6) for exhausting gas in the material injection zone (4). A liquid coating (7) is filled into the material injection zone (4) through the material injection port (5) to form a coating protection structure. The metal activity of the anode plate (2) is stronger than that of the metal of the lined steel pipe (1). The lined steel pipe (1) is connected to the anode plate (2) through a feeder cable (8) to form a cathodic protection structure of the weld of the lined steel pipe (1). The outer wall of the anode plate (2) is provided with an anti-corrosion layer (9); The outer side of the anode plate (2) is also provided with a fastening mechanism for adjusting the tightness of the anode plate (2); the outer wall of the anode plate (2) is provided with two fastening plates (10) extending outwards; the fastening mechanism is connected to the two fastening plates (10); and the tightness of the anode plate (2) is adjusted by adjusting the distance between the two fastening plates (10).

2. The shield tunnel lining steel pipe weld joint external joint protection structure according to claim 1 is characterized by: The fastening mechanism comprises a fastening screw (13) passing through two fastening plates (10), a nut (14) arranged at one end of the fastening screw (13), and a ratchet wrench (15) arranged at the other end of the fastening screw (13), and the two fastening plates (10) are arranged between the nut (14) and the ratchet wrench (15).

3. The shield tunnel lining steel pipe weld joint external joint protection structure according to claim 2 is characterized by: The ratchet wrench (15) is connected to a pull rope (16) for pulling the ratchet wrench to rotate, and the pull rope (16) is pulled into the lined steel pipe (1).

4. The shield tunnel lining steel pipe weld joint external joint protection structure according to claim 1 is characterized by: The exhaust hole (6) is covered with a screen (17), and the aperture of the screen (17) is smaller than the outer diameter of particles of the material in the liquid coating (7).

5. A construction process for the external joint protection structure of the shield tunnel lining steel pipe weld as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: First, send the first lining steel pipe into the shield tunnel and fix it; Step 2: Clean the loose rust on the outer end of the weld before butt jointing; Step 3: Sleeve and install the anode plate (2) on the end of the inner lining steel pipe to be connected, and install a traction rope (18) on the anode plate (2) for pulling the anode plate (2) to move; Step 4: pre-weld one end of the feeder cable (8) to the inner lining steel pipe to be connected, and weld the other end to the anode plate (2). The feeder cable (8) plays the role of impressed current; Step 5: gradually move the inner lining steel pipe to be connected closer to the first inner lining steel pipe for connection, and after the ends of the two inner lining steel pipes reach a certain distance, extend the traction rope (18) pre-arranged in step 3 to the inside of the first inner lining steel pipe; Step 6: Continue to move the inner lining steel pipe to be connected to the first inner lining steel pipe to achieve connection, and perform welding at the connection point of the two inner lining steel pipes; Step 7: After welding is completed, check the welding condition. The outer wall of the lining steel pipe extends outward with a limit plate (19). The anode plate (2) is pulled close to the limit plate (19) by the traction rope (18). Use an endoscope or a camera to check whether the anode plate (2) has moved into place. Step 8, after the anode plate (2) in step 7 is moved and checked to be correct, the anode plate (2) is retracted to reach a set torque, so that the anode plate (2) is attached to the outer wall of the lining steel pipe through two sealing strips (3) to form a material injection area (4) surrounding the outer periphery of the weld; Step 9: Use the injection machine to start injecting the coating into the injection port (5) through the feeding pipe. Stop injecting after the coating fills the injection interval (4) and forms a liquid coating (7) in the injection interval (4), and then withdraw the feeding pipe and auxiliary tools.

6. The construction process of the external joint protection structure of the shield tunnel lining steel pipe weld according to claim 5 is characterized by: In step nine, before using the injection machine to inject the paint into the injection port (5), check whether the construction environment temperature is suitable for painting. When the construction environment temperature is low, use an electric heating belt to heat the inside of the surrounding pipe for a period of time to make the outside temperature of the inner steel pipe reach the temperature most suitable for the fluidity of the paint, and then inject the paint into the injection port (5).

7. The construction process of the external joint protection structure of the shield tunnel lining steel pipe weld according to claim 6 is characterized by: In step nine, whether the paint fills the injection interval (4) is determined by using a probe to observe whether the paint flows out evenly from the exhaust hole (6). If the paint flows out evenly from the exhaust hole (6), the paint fills the injection interval (4); otherwise, the paint does not fill the injection interval (4).

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