Construction method for preventing shield from jamming at the end of a station based on the freezing reinforcement method

Abstract

The present invention discloses a shield construction method for preventing jamming at the station end based on the freezing reinforcement method. This method includes: First, the cutter head enters the frozen reinforcement area; Second, the shield body enters the frozen reinforcement area; Third, adjust the state of the frozen reinforcement area; Fourth, replace the freezing pipes; Fifth, the shield machine passes through the frozen reinforcement area. The present invention deals with the problem of shield machine jamming during freezing construction, and is applicable to both the starting stage of shield tunneling with frozen end reinforcement and the receiving process of shield tunneling with frozen end reinforcement; when the jamming problem occurs, it can not only prevent the cutter head from freezing and solve the shield jamming problem, but also protect the frozen curtain, ensure the end reinforcement effect, and at the same time ensure safe entry and exit during the freezing construction process.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel shield construction, and in particular relates to a shield construction method for preventing shield jamming at the end of a station based on the freezing reinforcement method. Background Technique

[0002] During the construction process of end reinforcement using the freezing method, the formation is usually soft soil with rich water. The freezing method has a unique effect on reinforcing this formation. However, when selecting the shield machine adaptively, the cutter configuration is usually scrapers for soft soil formations. This cutter configuration has a slow construction speed for the formation reinforced by the freezing method, and the effect of cutting frozen soil is average, resulting in an increase in the time for entering and exiting the tunnel. At the same time, before exiting the tunnel, it is necessary to carry out the work of removing the portal and installing the portal water stop curtain and hinge plate, with a pause in the middle for some time, increasing the risk of the shield body and the reinforced soil freezing into a whole, and the shield body being frozen to death by the surrounding freezing curtain, causing the problem of shield jamming. In traditional construction, usually, the telescopic hinge is used to move the shield body, or the number of active propulsion cylinders is increased to increase the thrust to get out of trouble. However, if the method of stopping freezing to get out of trouble is adopted after the shield machine gets jammed, it will affect the reinforcement effect, and there is a risk of mud and sand gushing during the process of removing the portal. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a shield construction method for preventing shield jamming at the end of a station based on the freezing reinforcement method in view of the above-mentioned deficiencies in the prior art. It can handle the shield jamming phenomenon of the shield machine during the freezing method construction, and is applicable to both the starting stage of the shield tunneling with freezing method end reinforcement and the receiving process of the shield tunneling with freezing method end reinforcement; when the shield jamming problem occurs, it can not only prevent the cutterhead from freezing and solve the shield jamming problem, but also protect the freezing curtain, ensure the end reinforcement effect, and at the same time ensure safe entry and exit of the tunnel during the freezing construction process.

[0004] To solve the above technical problem, the technical solution adopted by the present invention is: A shield construction method for preventing shield jamming at the end of a station based on the freezing reinforcement method, characterized in that: the method includes the following steps:

[0005] Step 1: The cutterhead enters the frozen reinforcement area: Adjust the tunneling parameters of the cutterhead and add foam agent into the soil bin; wherein, the injection amount of the foam agent is 300L / m 3 ~600L / m 3 ;

[0006] Step 2: The shield body enters the frozen reinforcement area: Switch to the hard rock tunneling parameters, increase the rotation speed of the cutterhead, and increase the thrust of the cylinder; at the same time, keep all equipment running continuously, observe the tunneling situation of the shield machine, and when the shield machine gets jammed, execute Step 3; otherwise, execute Step 4;

[0007] Step 3: Adjust the state of the frozen reinforcement area, and the process is as follows:

[0008] Step 301: Start the grease lubrication system inside the front shield, inject grease to the outside of the front shield, and form an isolation layer between the front shield and the frozen reinforcement layer.

[0009] Step 302: Adjust the flow rates of the freezing pipe assemblies in each layer of the frozen reinforcement layer, reduce the cold supply in the freezing pipe assemblies, and maintain the average temperature in the frozen reinforcement layer at -5°C.

[0010] Step Four: Replace the freezing pipes: When the cutter head enters the frozen reinforcement area, remove the multiple layers of freezing pipes near the portal side and arranged inside the frozen reinforcement area, install improved pipes at the installation positions of the original freezing pipes, and freeze and reinforce the area inside the frozen reinforcement area.

[0011] Step Five: The shield machine penetrates the frozen reinforcement area: The shield machine tunnels according to the designed route, and the cutter head starts to rotate slowly at a speed of 0.5 rpm every 5 minutes until the shield machine penetrates the frozen reinforcement area; wherein, the rotation speed of the cutter head is 0.5 rpm and it rotates for 5 minutes each time.

[0012] The above shield construction method for preventing jamming at the station end based on the frozen reinforcement method is characterized in that: in Step One, the foam agent includes a foam additive and water; wherein, the foam additive accounts for 5% of the mass ratio of the foam additive, and water accounts for 95% of the mass ratio of the foam additive.

[0013] The above shield construction method for preventing jamming at the station end based on the frozen reinforcement method is characterized in that: in Step Two, the rotation speed of the cutter head is adjusted to 1.5 rpm, and the thrust of the oil cylinder is adjusted to 32200 KN.

[0014] The above shield construction method for preventing jamming at the station end based on the frozen reinforcement method is characterized in that: in Step 301, the grease lubrication system includes a plurality of injection holes all opened on the front shield and a grease pump arranged inside the front shield and connected to the injection holes. The plurality of injection holes are arranged along the circumferential direction of the front shield, and the plurality of injection holes are symmetrically arranged on both sides of the front shield; the grease pump and the injection holes are connected through oil pipes.

[0015] The above-mentioned shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method is characterized in that: in step 302, the freezing pipe assembly includes a first freezing pipe unit, a second freezing pipe unit, a third freezing pipe unit, a fourth freezing pipe unit, and a fifth freezing pipe unit. The first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit are all connected to the cooling unit. The structures of the first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit are the same. Each of the first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit includes multiple freezing pipes. The freezing pipes are arranged along the extension direction of the freezing reinforcement area. The first freezing pipe unit and the second freezing pipe unit are arranged alternately. The third freezing pipe unit and the fourth freezing pipe unit are arranged alternately. The fifth freezing pipe unit is arranged between the second freezing pipe unit and the fourth freezing pipe unit;

[0016] A first ball valve is provided on the first freezing pipe unit, a second ball valve is provided on the second freezing pipe unit, a third ball valve is provided on the third freezing pipe unit, a fourth ball valve is provided on the fourth freezing pipe unit, and a fifth ball valve is provided on the fifth freezing pipe unit.

[0017] The above-mentioned shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method is characterized in that: in step 302, the process of adjusting the flow rate of the freezing pipe assembly is as follows: when the tunneling speed of the shield machine is not greater than 2 mm / min, adjust the first ball valve and the third ball valve and close them by half; when the tunneling speed of the shield machine is greater than 5 mm / min, adjust the first ball valve, the third ball valve, and the fifth ball valve and keep them in the fully open state.

[0018] The above-mentioned shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method is characterized in that: in step four, a partition plate is provided inside the improved pipe. The partition plate is arranged along the length direction of the improved pipe. The length of the partition plate is less than the length of the improved pipe. There is a gap between the partition plate and the bottom of the improved pipe. The partition plate divides the improved pipe into a forward path area and a return path area.

[0019] The above-mentioned shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method is characterized in that: in step five, when the shield machine exits the freezing reinforcement area, if the portal has not been chiseled out completely, the portal still needs to be chiseled. When chiseling the portal, the shield machine stops tunneling, and the cutter head rotates regularly according to the method in step five.

[0020] The present invention has the following advantages compared with the prior art:

[0021] 1. The present invention deals with the problem of the shield machine getting stuck during the construction by the freezing method. It can be applied not only to the starting stage of the shield tunneling with frozen-end reinforcement, but also to the receiving process of the shield tunneling with frozen-end reinforcement. When the problem of getting stuck occurs, it can prevent the cutter head from freezing, solve the problem of the shield machine getting stuck, protect the freezing curtain, ensure the reinforcement effect of the end, and ensure safe entry and exit during the freezing construction process.

[0022] 2. When the shield body passes through the portal, by increasing the thrust and the cutter head rotation speed, the shield machine can be slowly freed from the stuck state. At the same time, all equipment continues to operate, increasing the internal temperature of the shield machine, raising the temperature of the shield body and the frozen reinforced soil, and preventing the shield machine from getting stuck.

[0023] 3. When the shield body passes through the portal, by injecting lubricating grease around the shield body, an isolation layer is formed between the front shield and the frozen reinforcement layer, which can effectively reduce the freezing of the frozen soil around the shield body and achieve the water-stop effect at the same time.

[0024] 4. The present invention can control the flow rate of the freezing curtain and the opening and closing of the freezing pipeline by adjusting the flow rate of the freezing pipeline assembly and optimizing the layout of the freezing pipeline assembly according to the shield construction progress; reduce the cold supply to achieve the purpose of freeing the shield body of the shield machine.

[0025] 5. When the cutter head enters the frozen reinforcement area, the portal is chiseled, and the replacement freezing pipe method is adopted. During the process of chiseling the portal, the inner area of the freezing curtain is continuously frozen to ensure the freezing temperature.

[0026] In summary, the present invention deals with the problem of the shield machine getting stuck during the construction by the freezing method. It can be applied not only to the starting stage of the shield tunneling with frozen-end reinforcement, but also to the receiving process of the shield tunneling with frozen-end reinforcement. When the problem of getting stuck occurs, it can prevent the cutter head from freezing, solve the problem of the shield machine getting stuck, protect the freezing curtain, ensure the reinforcement effect of the end, and ensure safe entry and exit during the freezing construction process.

[0027] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the positional relationship between the front shield and the grease lubrication system of the present invention.

[0029] Figure 2 It is a schematic diagram of the construction state of injecting grease to the outside of the front shield of the present invention.

[0030] Figure 3 It is a schematic diagram of the structure of the freezing pipeline assembly of the present invention.

[0031] Figure 4 Schematic structural diagram of the improved pipe of the present invention.

[0032] Figure 5 Schematic layout diagram of the position of the freezing pipes in the freezing reinforcement area of the present invention.

[0033] Figure 6 Flow chart of the present invention.

[0034] Explanation of reference numerals:

[0035] 1 - Front shield; 2 - Freezing reinforcement layer; 3 - Isolation layer;

[0036] 4 - Injection hole; 5 - Grease pump; 6 - Freezing pipe;

[0037] 7 - First ball valve; 8 - Second ball valve; 9 - Third ball valve;

[0038] 10 - Fourth ball valve; 11 - Fifth ball valve; 12 - Brine outlet pipe;

[0039] 13 - Brine return pipe; 14 - Improved pipe; 15 - Partition board;

[0040] 16 - Cooling unit; 17 - Control valve; 18 - Freezing reinforcement area. Detailed implementation manner

[0041] As Figures 1 to 6 shown in the shield construction method for preventing stuck at the end of the station based on the freezing reinforcement method, this method includes the following steps:

[0042] Step 1, the cutter head enters the freezing reinforcement area: adjust the tunneling parameters of the cutter head and add foam agent into the soil bin; wherein, the injection volume of the foam agent is 300L / m 3 ~600L / m 3 ;

[0043] Step 2, the shield body enters the freezing reinforcement area: switch to the hard rock tunneling parameters, increase the rotation speed of the cutter head, and increase the thrust of the cylinder; at the same time, keep all equipment running continuously, observe the tunneling situation of the shield machine, and when the shield machine gets stuck, execute Step 3; otherwise, execute Step 4;

[0044] Step 3, adjust the state of the freezing reinforcement area, the process is as follows:

[0045] Step 301, start the grease lubrication system in the front shield 1, inject grease to the outside of the front shield 1, and form an isolation layer 3 between the front shield 1 and the freezing reinforcement layer 2;

[0046] Step 302: Adjust the flow rates of the freezing pipe assemblies in the freezing reinforcement layer 2 to reduce the cold supply within the freezing pipe assemblies, and maintain the average temperature within the freezing reinforcement layer 2 at -5°C.

[0047] Step Four: Replace the freezing pipes: When the cutter head enters the frozen reinforcement area, remove the multiple layers of freezing pipes 6 that are close to the portal side and are arranged inside the frozen reinforcement area 18, install the improved pipes 14 at the original installation positions of the freezing pipes 6, and freeze and reinforce the area inside the frozen reinforcement area 18.

[0048] Step Five: The shield machine passes through the frozen reinforcement area: The shield machine tunnels according to the designed route, and the cutter head starts to rotate slowly at a low speed every 5 minutes until the shield machine passes through the frozen reinforcement area; wherein, the rotation speed of the cutter head is 0.5 rpm, and it rotates for 5 minutes each time.

[0049] The present invention deals with the problem of the shield machine getting stuck during the construction by freezing method. It can be applied to both the starting stage of the shield tunneling with frozen end reinforcement and the receiving process of the shield tunneling with frozen end reinforcement; when the problem of getting stuck occurs, it can prevent the cutter head from freezing and solve the problem of the shield machine getting stuck, protect the frozen curtain, ensure the end reinforcement effect, and ensure safe entry and exit during the freezing construction process.

[0050] When the shield body passes through the portal, the present invention increases the thrust and the rotation speed of the cutter head to slowly disengage the shield machine. At the same time, all equipment continues to operate, increasing the internal temperature of the shield machine, raising the temperature of the shield body and the frozen reinforced soil, and preventing the shield machine from getting stuck.

[0051] When the shield body passes through the portal, the present invention forms an isolation layer 3 between the front shield 1 and the freezing reinforcement layer 2 by injecting lubricating grease around the shield body, which can effectively reduce the freezing of the frozen soil around the shield body and achieve the effect of water stop at the same time.

[0052] The present invention can control the flow rate of the frozen curtain and the opening and closing of the freezing pipelines according to the shield construction progress by adjusting the flow rates of the freezing pipe assemblies and optimizing the layout of the freezing pipe assemblies; reduce the cold supply to achieve the purpose of disengaging the shield body of the shield machine.

[0053] When the cutter head enters the frozen reinforcement area, the present invention chisels the portal, adopts the method of replacing the freezing pipes, and continues to freeze the area inside the frozen curtain during the portal chiseling process to ensure the freezing temperature.

[0054] It should be noted that the construction process in the present invention is carried out after the shield machine passes through the diaphragm wall. After passing through the diaphragm wall, the shield machine reaches the frozen reinforcement area 18. After passing through the frozen reinforcement area 18, the shield machine reaches the receiving end to complete the shield tunneling.

[0055] In Step 101, when the cutter head of the shield machine has completed tunneling and has not contacted the portal, there is a shutdown gap for segment erection, with an average duration of 45 minutes. Therefore, the cutter head is rotated at a low speed to increase the agitation of the soil mass in the cutter head soil bin and prevent the soil mass in the soil bin from freezing and jamming the cutter head. Secondly, heat is dissipated during the rotation of the motor, increasing the internal temperature of the front shield and reducing the freezing risk.

[0056] In Step 102, during the removal of the portal, the shield machine stops tunneling for safety considerations.

[0057] In Step 201, by increasing the cylinder thrust and the cutter head rotation speed, it slowly gets out of trouble. At the same time, each device continues to operate, increasing the internal temperature of the shield machine and raising the temperature of the shield body and the frozen reinforced soil mass.

[0058] In this embodiment, in Step 1, the foam agent includes a foam additive and water; among them, the foam additive accounts for 5% of the mass ratio of the foam additive, and water accounts for 95% of the mass ratio of the foam additive.

[0059] In actual use, the freezing point of the foam agent is -5°C to 10°C. After adding the foam agent, the cutting effect of the cutter head on frozen soil can be increased, the cutter head torque can be reduced, and at the same time, the freezing and solidification temperature point of the muck can be reduced, reducing the freezing risk of the cutter head.

[0060] In this embodiment, in Step 2, the rotation speed of the cutter head is adjusted to 1.5 rpm, and the cylinder thrust is adjusted to 32200 KN.

[0061] As Figure 1 shown, in this embodiment, in Step 301, the grease lubrication system includes a plurality of injection holes 4 all opened on the front shield 1 and a grease pump 5 disposed inside the front shield 1 and connected to the injection holes 4. The plurality of injection holes 4 are arranged along the circumferential direction of the front shield 1, and the plurality of injection holes 4 are symmetrically arranged on both sides of the front shield 1; the grease pump 5 and the injection holes 4 are connected by an oil pipe.

[0062] During actual use, the grease pump 5 is provided with the EP2 grease pump of the shield machine 2 as the grease source; the number of the injection holes 4 is preferably 4, and the injection holes 4 are modified from the reserved holes on the front shield 1. By injecting EP2 grease on the outside of the shield body, a grease coating layer can be formed around the shield body, and the periphery of the shield body can be lubricated to reduce friction. At the same time, it can withstand the influence of low temperatures, and can fill the gaps around the shield body to stop water, preventing the groundwater behind the segments from flowing from the outside of the shield body to the soil bin to form a water loop. Once a water loop is formed around the shield body, the loop will gradually increase due to the rapid removal of heat, which will quickly destroy the freezing reinforcement curtain and cause the risk of water and mud gushing. The normal excavation dosage of EP2 is 3kg to 5kg per ring. After increasing the injection of grease on the outside of the shield body, it increases to 25kg to 45kg per ring. When the excavation parameters of the shield machine are normal and the shield body is out of trouble, that is, the excavation speed is greater than 4mm, the amount of grease can be gradually reduced until it stops. Figure 1 As shown, a regulating valve 17 is installed on the grease pump 5 for adjusting the amount of injected grease.

[0063] like Figure 3 As shown, in this embodiment, in step 302, the freezing pipe assembly includes a first freezing pipe unit, a second freezing pipe unit, a third freezing pipe unit, a fourth freezing pipe unit, and a fifth freezing pipe unit. The first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit are all connected to the cooling unit 16. The first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit have the same structure. The first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit all include a plurality of freezing pipes 6. The freezing pipes 6 are arranged along the extension direction of the freezing reinforcement area 18. The first freezing pipe unit and the second freezing pipe unit are alternately arranged, the third freezing pipe unit and the fourth freezing pipe unit are alternately arranged, and the fifth freezing pipe unit is arranged between the second freezing pipe unit and the fourth freezing pipe unit.

[0064] The first freezing pipe unit is provided with a first ball valve 7, the second freezing pipe unit is provided with a second ball valve 8, the third freezing pipe unit is provided with a third ball valve 9, the fourth freezing pipe unit is provided with a fourth ball valve 10, and the fifth freezing pipe unit is provided with a fifth ball valve 11.

[0065] like Figure 3As shown, there are 6 or 7 freezing pipes 6 in each of the first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit. The cooling unit 16 transports brine into each freezing pipe unit through the brine outlet pipe 12, and after flowing through each freezing pipe unit, it returns to the cooling unit 16 through the brine return pipe 13. Before the shield machine reaches the freezing curtain during the active freezing stage, the first ball valve 7, the second ball valve 8, the third ball valve 9, the fourth ball valve 10, and the fifth ball valve 11 are all in the fully open state, and the brine temperature is -28°C.

[0066] In this embodiment, in step 302, the process of adjusting the flow rate of the freezing pipe assembly is as follows: when the tunneling speed of the shield machine is not greater than 2 mm / min, adjust the first ball valve 7 and the third ball valve 9, and close the first ball valve 7 and the third ball valve 9 by half; when the tunneling speed of the shield machine is greater than 5 mm / min, adjust the first ball valve 7, the third ball valve 9, and the fifth ball valve 11, and make the first ball valve 7, the third ball valve 9, and the fifth ball valve 11 in the fully open state.

[0067] During actual use, when the tunneling speed of the shield machine is not greater than 2 mm / min, it indicates that the shield machine is stuck. Adjust the first ball valve 7 and the third ball valve 9 to reduce the flow rate of the freezing pipes and the cold supply. At the same time, stabilize the curtain temperature according to the soil temperature sensor inside the soil, and continuously control the freezing curtain temperature at -5°C without further decrease. When the tunneling speed of the shield machine is greater than 5 mm / min, it indicates that the stuck situation of the shield machine has been alleviated, and then the flow rate of the freezing pipe assembly needs to reach the maximum to ensure the freezing effect. By arranging the freezing pipes crosswise and controlling the flow rate of the freezing pipes to reduce the cold supply, the purpose of getting the shield body of the shield machine out of trouble is achieved.

[0068] As Figure 4 shown, in this embodiment, in step four, a partition plate 15 is provided in the improved pipe 14. The partition plate 15 is arranged along the length direction of the improved pipe 14. The length of the partition plate 15 is less than the length of the improved pipe 14. There is a gap between the partition plate 15 and the bottom of the improved pipe 14. The partition plate 15 divides the improved pipe 14 into an outlet area and a return area.

[0069] In this embodiment, in step five, when the shield machine passes through the frozen reinforcement area, if the portal has not been completely chiseled, the portal still needs to be chiseled. When chiseling the portal, the shield machine stops tunneling, and the cutter head rotates regularly according to the method in step five.

[0070] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. Shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method, characterized in that, The method comprises the following steps: Step 1, the cutter head enters the frozen reinforcement area: adjust the tunneling parameters of the cutter head and add foaming agent into the soil bin; wherein, the injection amount of the foaming agent is 300 L / m3 to 600 L / m3; Step 2, the shield body enters the frozen reinforcement area: switch to hard rock tunneling parameters, increase the rotation speed of the cutter head, and increase the thrust of the oil cylinder; meanwhile, keep all equipment running continuously, observe the tunneling condition of the shield machine, and execute Step 3 when the shield machine gets stuck; otherwise, execute Step 4; Step 3, adjust the state of the frozen reinforcement area, and the process is as follows: Step 301, start the grease lubrication system in the front shield (1), inject grease to the outside of the front shield (1), and form an isolation layer (3) between the front shield (1) and the frozen reinforcement layer (2); Step 302, adjust the flow rate of each layer of freezing pipe assembly in the frozen reinforcement layer (2), reduce the cold supply in the freezing pipe assembly, and keep the average temperature in the frozen reinforcement layer (2) at -5°C; Step 4, replace the freezing pipes: when the cutter head enters the frozen reinforcement area, remove the multi-layer freezing pipes (6) near the portal side and arranged inside the frozen reinforcement area (18), install the improved pipes (14) at the installation positions of the original freezing pipes (6), and freeze and reinforce the area inside the frozen reinforcement area (18); Step 5, the shield machine exits the frozen reinforcement area: the shield machine tunnels according to the designed route, and the cutter head starts to rotate slowly every 5 minutes until the shield machine exits the frozen reinforcement area; wherein, the rotation speed of the cutter head is 0.5 rpm and it rotates for 5 minutes each time; In Step 302, the freezing pipe assembly includes a first freezing pipe unit, a second freezing pipe unit, a third freezing pipe unit, a fourth freezing pipe unit, and a fifth freezing pipe unit. The first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit are all connected to the cooling unit (16). The structures of the first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit are the same. The first freezing pipe unit, the second freezing pipe unit, the third freezing pipe unit, the fourth freezing pipe unit, and the fifth freezing pipe unit each include multiple freezing pipes (6). The freezing pipes (6) are arranged along the extension direction of the frozen reinforcement area (18). The first freezing pipe unit and the second freezing pipe unit are arranged alternately. The third freezing pipe unit and the fourth freezing pipe unit are arranged alternately. The fifth freezing pipe unit is arranged between the second freezing pipe unit and the fourth freezing pipe unit; A first ball valve (7) is arranged on the first freezing pipe unit, a second ball valve (8) is arranged on the second freezing pipe unit, a third ball valve (9) is arranged on the third freezing pipe unit, a fourth ball valve (10) is arranged on the fourth freezing pipe unit, and a fifth ball valve (11) is arranged on the fifth freezing pipe unit.

2. The shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method according to claim 1, wherein: In step 1, the foaming agent includes a foam additive and water; wherein the foam additive accounts for 5% of the mass ratio of the foam additive, and the water accounts for 95% of the mass ratio of the foam additive.

3. The shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method according to claim 1, characterized in that: In step 2, the rotation speed of the cutter disc is adjusted to 1.5 rpm and the cylinder thrust is adjusted to 32200 KN.

4. The shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method according to claim 3, wherein: In step 301, the grease lubrication system includes a plurality of injection holes (4) each provided on the front shield (1) and a grease pump (5) provided in the front shield (1) and connected to the injection holes (4), wherein the plurality of injection holes (4) are arranged along the circumferential direction of the front shield (1), and the plurality of injection holes (4) are symmetrically arranged on both sides of the front shield (1); and the grease pump (5) and the injection holes (4) are connected via an oil pipe.

5. The shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method according to claim 1, characterized in that: In step 302, the process of adjusting the flow of the freezing pipe assembly is as follows: when the tunneling speed of the shield machine is not greater than 2 mm / min, the first ball valve (7) and the third ball valve (9) are adjusted, and the first ball valve (7) and the third ball valve (9) are half closed; when the tunneling speed of the shield machine is greater than 5 mm / min, the first ball valve (7), the third ball valve (9) and the fifth ball valve (11) are adjusted, and the first ball valve (7), the third ball valve (9) and the fifth ball valve (11) are fully opened.

6. The shield construction method for preventing jamming at the station end based on the freezing reinforcement method according to claim 1, characterized in that: In step 4, a partition plate (15) is provided in the improved tube (14). The partition plate (15) is arranged along the length direction of the improved tube (14). The length of the partition plate (15) is less than the length of the improved tube (14). There is a gap between the partition plate (15) and the bottom of the improved tube (14). The partition plate (15) divides the improved tube (14) into an outgoing zone and a returning zone.

7. The shield construction method for preventing jamming at the end of a station based on the freezing reinforcement method according to claim 1, characterized in that: In step five, when the shield machine passes through the frozen reinforcement area, if the tunnel portal has not been chiseled out, it is necessary to chisel out the tunnel portal. When the tunnel portal is chiseled out, the shield machine stops excavating, and the cutterhead keeps rotating regularly according to the method in step five.

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