A Shield Machine Main Drive Sealing Test System and Test Method

Abstract

The present invention provides a main drive seal test system for a shield machine. The system includes an air source, a pressure setting module, a differential pressure regulating module, a pressure relief module, and a water and soil pressure simulation module; one end of the pressure setting module is connected to the water and soil pressure simulation module, and the other end is connected in parallel with the differential pressure regulating module to the air source; the differential pressure regulating module and the pressure relief module are connected to the rear seal cavity of the main drive seal; the water and soil pressure simulation module is connected to the front seal cavity of the main drive seal; the control ends of the differential pressure regulating module and the pressure relief module are connected to the water and soil pressure simulation module to adjust the differential pressure between the front and rear seal cavities. The present invention also provides a main drive seal test method for a shield machine. The method includes first adjusting the spring pre-tightening forces of the differential pressure regulating valve, the overpressure protection valve, and the safety valve, and then adjusting the outlet pressure of the pressure regulating valve for testing. By adjusting the spring pre-tightening forces of each pressure control valve, the present invention keeps the differential pressure between the front and rear seal cavities of the main drive seal stable during testing.

Description

Technical Field

[0001] The present invention relates to the technical field of main drive seal testing, and particularly relates to a main drive seal testing system and testing method for a shield machine. Background Art

[0002] With the in-depth development of the country's infrastructure construction, the construction of large-section, large-buried depth, high-water pressure, and long-distance tunnels has been gradually carried out. To cope with these complex and harsh working conditions, shield machines are mostly used for tunnel construction. The main drive is an important part of the shield machine, and the quality of its sealing performance directly determines the size of the water and soil pressure-bearing capacity of the shield machine. At present, lip-shaped rubber seals are mainly used for the main drive of the shield machine. To improve the water and soil pressure-bearing capacity, generally four sealing lips are set. A labyrinth cavity is machined outside the first sealing lip, and high-fiber grease is continuously injected into the cavity to resist the intrusion of external mud and slag. The grease cavity formed by the first and second sealing lips will continuously inject grease, which on the one hand further improves the main drive sealing ability, and on the other hand lubricates and reduces friction of the sealing lips. The annular cavity formed by the second and third sealing lips is an oil and gas sealing cavity, that is, when the external water pressure exceeds a certain value, this cavity will inject gear oil and be pressurized with air to provide a supporting force for the sealing lips. The third and fourth sealing lips are generally installed reversely to form a leakage detection cavity. The fourth sealing lip mainly seals the gearbox to prevent internal gear oil leakage.

[0003] The pressure-bearing capacity of a single lip-shaped rubber seal is generally about 3 bar. When the water and soil pressure is less than 3 bar, the grease pressure in the grease cavity can be relied on to resist the external water and soil pressure to ensure reliable sealing of the main drive. When the water and soil pressure is greater than 3 bar and less than 6 bar, the external water and soil pressure can also be resisted by pressurizing the oil and gas sealing cavity. When the shield machine operates under high water pressure with large buried depth, when the water and soil pressure exceeds 6 bar, it is necessary to pressurize the oil and gas sealing cavity, the leakage detection cavity, and the gearbox respectively to resist the external high water pressure. During the pressurization process of the oil and gas sealing cavity, the leakage detection cavity, and the gearbox, to ensure that the seal is not damaged, it is necessary to ensure the stability of the pressure difference between the front sealing cavity and the rear sealing cavity of the seal, and the maximum error of the pressure difference is not greater than 0.2 bar.

[0004] Since it is difficult to simulate the change of the water and soil pressure of the face during the workshop debugging stage of the shield machine, the main drive seal testing system is difficult to be successfully debugged. In addition, if it is debugged at the construction site, the unstable operation of the main drive seal pressurization system will cause the face mud and slag to enter the main drive seal, which has potential safety hazards.

[0005] In summary, there is an urgent need for a main drive seal testing system and testing method for a shield machine to solve the problems existing in the prior art. Summary of the Invention

[0006] The object of the present invention is to provide a shield machine main drive seal test system and a test method to solve the problem of maintaining a stable pressure difference between the front seal cavity and the rear seal cavity during the main drive seal test.

[0007] To achieve the above object, the present invention provides a shield machine main drive seal test system, including an air source, a pressure setting module, a pressure difference adjustment module, a pressure relief module, and a soil and water pressure simulation module; one end of the pressure setting module is connected to the soil and water pressure simulation module, and the other end is connected in parallel with the pressure difference adjustment module to the air source; the pressure difference adjustment module is connected to the rear seal cavity of the main drive seal for detecting and adjusting the pressure of the rear seal cavity; the air inlet end of the pressure relief module is connected to the rear seal cavity, and the control end of the pressure relief module is connected to the soil and water pressure simulation module; the soil and water pressure simulation module is connected to the front seal cavity of the main drive seal for detecting and adjusting the pressure of the front seal cavity;

[0008] The control end of the pressure difference regulating valve of the pressure difference adjustment module is connected to the soil and water pressure simulation module to realize the adjustment of the pressure of the rear seal cavity.

[0009] Preferably, the pressure setting module includes a ball valve 1, a check valve, a pressure regulating valve, a pressure gauge 1, a ball valve 2, a single-acting ball valve 1, a pressure gauge 2, and a pressure sensor 1 connected in sequence; used to adjust the inlet air pressure of the soil and water pressure simulation module.

[0010] Preferably, the pressure difference adjustment module includes a ball valve 3, a single-acting ball valve 2, a pressure gauge 3, a pressure difference regulating valve, and a pressure sensor 2 connected in sequence; the pressure sensor 2 is connected to the rear seal cavity for detecting and displaying the pressure of the rear seal cavity.

[0011] Preferably, the pressure regulating valve is a pressure reducing valve.

[0012] Preferably, the pressure relief module includes a pressure overprotection valve and a silencer 1 connected in sequence; the air inlet end of the pressure overprotection valve is connected to the rear seal cavity; the control end of the pressure overprotection valve is connected to the soil and water pressure simulation module.

[0013] Preferably, the soil and water pressure simulation module includes an air tank simulation chamber, a single-acting ball valve 3, a globe valve, and a silencer 2 connected in sequence; the air tank simulation chamber is connected to a safety valve to prevent accidental expansion of the air tank simulation chamber.

[0014] Preferably, the air tank simulation chamber is connected to the control ends of the pressure difference regulating valve and the pressure overprotection valve through a ball valve 4.

[0015] Preferably, the safety valve is a relief valve.

[0016] The present invention also provides a shield machine main drive seal testing method, which adopts the above shield machine main drive seal testing system to test the performance of the main drive seal under different pressure levels. The specific steps are as follows:

[0017] Step 1: According to the experimental requirements, adjust the spring pre-tightening forces of the differential pressure regulating valve, overpressure protection valve, and safety valve;

[0018] Step 2: According to the experimental requirements, adjust the outlet pressure of the pressure calibration valve to the test pressure required for the experiment, open all ball valves, and connect the gas source to conduct the test experiment.

[0019] Applying the technical solution of the present invention has the following beneficial effects:

[0020] (1) In the present invention, by setting the differential pressure regulating valve and the overpressure protection valve and adjusting the spring pre-tightening forces of the two, the pressure difference between the front seal cavity and the rear seal cavity during the test of the main drive seal is kept stable.

[0021] (2) In the present invention, by setting the spring pre-tightening force of the pressure regulating valve, it can output different outlet air pressures and can simulate the test experiment of the main drive seal under multi-stage pressure conditions.

[0022] (3) In the present invention, by setting the air tank simulation chamber, the effect of soil and water pressure on the main drive seal can be simulated, avoiding the damage of the main drive seal caused by improper actual operation during commissioning in the workshop and on the construction site.

[0023] (4) In the present invention, by setting the pressure gauge and the pressure sensor, the debugging personnel can intuitively understand the pressure conditions of each part, can normally record the test data or promptly handle abnormal situations. By setting multiple ball valves, sectional closing and pressure maintaining can be carried out during maintenance.

[0024] (5) In the present invention, by setting the single-acting pneumatic ball valve, the system can be pressure maintained in the case of power failure, preventing damage to the test system caused by sudden power failure; by setting the safety valve, accidental expansion of the air tank simulation chamber can be prevented, making the pneumatic system operate stably.

[0025] (6) In the present invention, by adjusting the spring pre-tightening forces of the differential pressure regulating valve, overpressure protection valve, safety valve, and pressure regulating valve, the seal performance test of the main drive seal under different pressure levels can be completed. The operation is simple, easy to apply, and can effectively improve the test efficiency.

[0026] In addition to the purposes, features, and advantages described above, the present invention has other purposes, features, and advantages. The following will refer to the drawings to further elaborate on the present invention in detail. Brief Description of the Drawings

[0027] The accompanying drawings, which form a part of this application, are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0028] Figure 1 is a schematic connection diagram of a main drive seal test system for a shield machine;

[0029] Figure 2 is a schematic diagram of the main drive seal structure;

[0030] Figure 3 is a schematic diagram of a differential pressure regulating valve;

[0031] Figure 4 is a schematic diagram of an overpressure protection valve.

[0032] Among them, 1 is an air source, 2 is a pressure setting module, 21 is a ball valve 1, 22 is a check valve, 23 is a pressure regulating valve, 24 is a pressure gauge 1, 25 is a ball valve 2, 26 is a single-acting ball valve 1, 27 is a pressure gauge 2, 28 is a pressure sensor 1, 3 is a differential pressure regulating module, 31 is a ball valve 3, 32 is a single-acting ball valve 2, 33 is a pressure gauge 3, 34 is a differential pressure regulating valve, 35 is a pressure sensor 2, 4 is a pressure relief module, 41 is an overpressure protection valve, 42 is a silencer 1, 5 is a soil and water pressure simulation module, 51 is an air tank simulation chamber, 52 is a single-acting ball valve 3, 53 is a globe valve, 54 is a silencer 2, 55 is a safety valve, 56 is a ball valve 4, 6 is the main drive seal, 61 is the rear seal cavity, 62 is the front seal cavity, 63 is a seal, and 64 is a sealing ring. Detailed Embodiments

[0033] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways defined and covered by the claims.

[0034] See Figures 1 to 4 , a main drive seal test system for a shield machine, and this embodiment is applied to the pressure test of the main drive seal of a shield machine.

[0035] A main drive seal test system for a shield machine includes an air source 1, a pressure setting module 2, a differential pressure regulating module 3, a pressure relief module 4, and a soil and water pressure simulation module 5; see Figure 2 , the sealing ring 64 and the seal 63 form the front seal cavity 62 and the rear seal cavity 61 of the main drive seal 6, and the front seal cavity 62 and the rear seal cavity 61 are both provided with air injection holes for connection to the seal test system; see Figure 1, one end of the pressure setting module 2 is connected to the water and soil pressure simulation module 5, and the other end is connected in parallel with the differential pressure regulating module 3 to the gas source 1; the differential pressure regulating module 3 is connected to the rear sealing cavity 61 of the main drive seal 6 for detecting and regulating the pressure in the rear sealing cavity 61; the air inlet end of the pressure relief module 4 is connected to the rear sealing cavity 61, and the control end of the pressure relief module 4 is connected to the water and soil pressure simulation module 5; the water and soil pressure simulation module 5 is connected to the front sealing cavity 62 of the main drive seal 6 for detecting and regulating the pressure in the front sealing cavity 62.

[0036] The control end of the differential pressure regulating valve 34 of the differential pressure regulating module 3 is connected to the water and soil pressure simulation module 5 for adjusting the pressure in the rear sealing cavity 61.

[0037] See Figure 1 , the pressure setting module 2 includes a ball valve 21, a check valve 22, a pressure regulating valve 23, a pressure gauge 24, a ball valve 25, a single-acting ball valve 26, a pressure gauge 27 and a pressure sensor 28 connected in sequence; the ball valve 21 and the ball valve 25 are used to close the gas circuit in sections and maintain pressure during maintenance, the pressure gauge 24 is used to measure the outlet air pressure of the pressure regulating valve 23, and the pressure gauge 27 and the pressure sensor 28 are used to measure the inlet air pressure of the water and soil pressure simulation module 5; the single-acting ball valve 26 is opened when powered on and closed when powered off, and its control method can be pneumatic, hydraulic or electromagnetic control. When the test system suddenly loses power, the single-acting ball valve 26 closes, and the water and soil pressure simulation module 5 can be maintained under pressure; after the system loses power, due to the failure of the pressure sensor 28, the inlet air pressure of the water and soil pressure simulation module 5 cannot be intuitively displayed, and it can be observed through the pressure gauge 27; the pressure regulating valve 23 is used to adjust the outlet pressure of the pressure regulating valve 23 and the inlet air pressure of the water and soil pressure simulation module 5.

[0038] See Figure 1 , the differential pressure regulating module 3 includes a ball valve 31, a single-acting ball valve 32, a pressure gauge 33, a differential pressure regulating valve 34 and a pressure sensor 35 connected in sequence; the pressure sensor 35 is connected to the rear sealing cavity 61, the ball valve 31 is used to close the gas circuit in sections and maintain pressure during maintenance, the single-acting ball valve 32 is opened when powered on and closed when powered off, and its control method can be pneumatic, hydraulic or electromagnetic control. When the test system suddenly loses power, the single-acting ball valve 32 closes, and the inlet air pressure of the differential pressure regulating valve 34 can be maintained under pressure, so that the outlet pressure of the differential pressure regulating valve 34, that is, the pressure in the rear sealing cavity 61 of the main drive seal, remains stable; the pressure gauge 33 is used to measure the inlet air pressure of the differential pressure regulating valve 34, and the pressure sensor 35 is used to measure and intuitively display the outlet air pressure of the differential pressure regulating valve 34; the differential pressure regulating valve 34 is used to adjust the pressure in the rear sealing cavity of the main drive seal 6.

[0039] See Figure 1 , the pressure regulating valve 23 is a pressure reducing valve. By adjusting the spring pre-tightening force of the pressure regulating valve 23, the required pressure range for the test can be achieved.

[0040] See Figure 1 , the pressure relief module 4 includes a overpressure protection valve 41 and a muffler 42 connected in sequence; the intake end of the overpressure protection valve 41 is connected to the rear sealing cavity 61; the control end of the overpressure protection valve 41 is connected to the soil and water pressure simulation module 5. When the sum of the intake pressure and the spring pre-tightening force of the overpressure protection valve 41 is greater than the control pressure, the overpressure protection valve 41 starts to relieve pressure to keep the pressure difference between the front sealing cavity 62 and the rear sealing cavity 61 of the main drive seal 6 stable, and the muffler 42 can reduce noise during the pressure relief process.

[0041] See Figure 1 , the soil and water pressure simulation module 5 includes an air tank simulation chamber 51, a single-acting ball valve 52, a globe valve 53 and a muffler 54 connected in sequence; the globe valve 53 is used to close the air circuit to keep the air tank simulation chamber 51 pressurized. The single-acting ball valve 52 opens when energized and closes when de-energized. Its control method can be pneumatic, hydraulic or electromagnetic control. When the test system suddenly loses power, the single-acting ball valve 52 closes to keep the pressure of the air tank simulation chamber 51 pressurized, so as to keep the pressure of the front sealing cavity 62 of the main drive seal stable; when the pressure of the air tank simulation chamber 51 is too high, the globe valve 53 can be opened to relieve pressure, and the muffler 54 can reduce noise during the pressure relief process.

[0042] See Figure 1 , the air tank simulation chamber 51 is connected to a safety valve 55 to prevent the air tank simulation chamber 51 from accidentally bulging.

[0043] See Figure 1 , the air tank simulation chamber 51 is connected to the control ends of the differential pressure regulating valve 34 and the overpressure protection valve 41 through a ball valve 56 to provide control pressure for the differential pressure regulating valve 34 and the overpressure protection valve 41.

[0044] See Figure 1 , the air tank simulation chamber 51 is connected to the front sealing cavity 62 through a ball valve 57 to adjust the pressure of the front sealing cavity 62 of the main drive seal 6.

[0045] See Figure 1 , the safety valve 55 is a relief valve to keep the pressure of the air tank simulation chamber stable.

[0046] The working principle of the above-mentioned main drive seal test system for a shield machine is: See Figures 3 to 4 , the intake pressure of the differential pressure regulating valve 34 is P 1, the outlet pressure of the differential pressure regulating valve 34 is P 2 , the control pressure of the differential pressure regulating valve 34 is P C ; Since the inlet end of the overpressure protection valve 41 is connected to the outlet end of the differential pressure regulating valve 34, the inlet pressure of the overpressure protection valve 41 is P 2 , since the control end of the overpressure protection valve 41 is connected to the control end of the differential pressure regulating valve 34, the control pressure of the overpressure protection valve 41 is also P C , the outlet pressure of the overpressure protection valve 41 is P 3 ; Since the pressure regulating valve 23, the air tank simulation chamber 51 and the front sealing chamber 62 are connected to the control end of the differential pressure regulating valve 34, the outlet pressure of the pressure regulating valve 23, the pressure of the air tank simulation chamber 51 and the pressure of the front sealing chamber 62 are also P C .

[0047] The force analysis of the differential pressure regulating valve 34 is as follows: where ΔP 1 is the pressure difference across the differential pressure regulating valve 34; k 1 is the stiffness of the regulating spring of the differential pressure regulating valve 34; A 1 is the equivalent area of the valve core of the differential pressure regulating valve 34. When the differential pressure regulating valve 34 is actually working, the displacement Δx of the valve core is very small and can be ignored. The equivalent area A 1 of the valve core is a constant value. From the force analysis formula of the differential pressure regulating valve 34, it can be seen that the pressure difference ΔP 1 across it is a constant value, that is, the pressure difference between the front sealing chamber 62 and the rear sealing chamber 61 of the main drive seal 6 is a constant value, which is only related to the spring pre-tightening force of the differential pressure regulating valve 34. The differential pressure regulating valve 34 is a self-acting differential pressure control valve. When it is in the normal position, the valve core is closed. The opening degree of the valve core increases with the increase of the differential pressure. When the differential pressure reaches the preset value of the spring pre-tightening force, the valve core is fully opened. The valve core of the differential pressure regulating valve 34 is in the closed state when it is not affected by the control pressure P C , and when P C is greater than the spring pre-tightening force, the valve core opens and the differential pressure regulating valve 34 starts to ventilate.

[0048] The force analysis of the overpressure protection valve 41 is as follows: ΔP 2 is the pressure difference across the overpressure protection valve 41; k 2 is the stiffness of the regulating spring of the overpressure protection valve 41; A 2 is the equivalent area of the valve core of the overpressure protection valve 41. When the overpressure protection valve 41 is actually working, the displacement Δy of the valve core is very small and can be ignored. The equivalent area A 2 of the valve core is a constant value. From the force analysis formula of the overpressure protection valve 41, it can be seen that the pressure difference ΔP 2is a fixed value and is only related to the spring pre-tightening force of the overpressure protection valve 41. The overpressure protection valve 41 is a self-acting differential pressure control valve. When in the normal position, its valve core is open, and as the differential pressure increases, the valve core starts to close. When the differential pressure reaches the preset value of the spring pre-tightening force, the valve core is completely closed. The valve core of the overpressure protection valve 41 is in the open state when not affected by the control pressure P C acts, and when P C starts to act, the valve core closes, but when the inlet pressure P 2 increases to the sum of it and the spring pre-tightening force is greater than the control pressure P C , the valve core opens.

[0049] During actual testing, the spring pre-tightening force of the overpressure protection valve 41 is usually set to be 0.2 bar less than the spring pre-tightening force of the differential pressure regulating valve 34. Assume that the spring pre-tightening force of the differential pressure regulating valve 34 is adjusted to 2.5 bar, and the spring pre-tightening force of the overpressure protection valve 41 is adjusted to 2.3 bar. Close the stop valve 53 and open the rest of the ball valves; adjust the outlet pressure of the pressure regulating valve 23 to 2.5 bar. At this time, the pressure in the air tank simulation chamber 51 is 2.5 bar, that is, the pressure in the front-side sealing cavity 62 before sealing is 2.5 bar, and the pressure at the outlet of the differential pressure regulating valve 34, that is, the pressure in the rear-side sealing cavity 61, is 0 bar, and the overpressure protection valve 41 is closed; if the outlet pressure of the pressure regulating valve 23 is adjusted to 3 bar, at this time, the pressure in the air tank simulation chamber 51 is 3 bar, that is, the pressure in the front-side sealing cavity 62 is 3 bar, and the pressure at the outlet of the differential pressure regulating valve 34, that is, the pressure in the rear-side sealing cavity 61, is 0.5 bar, and the overpressure protection valve 13 is closed. The differential pressure between the front-side sealing cavity 62 and the rear-side sealing cavity of the main drive seal 6 is stable in both tests, both being 2.5 bar. If at this time, due to a malfunction overshoot of the pneumatic control system, the pressure in the rear-side sealing cavity 61 is greater than or equal to 0.7 bar, at this time, the overpressure protection valve 41 opens to start relieving pressure, and the air pressure is discharged to the atmosphere through the silencer one 42 until the pressure in the rear-side sealing cavity 61 is less than 0.7 bar, and the overpressure protection valve 41 closes to stop relieving pressure. At this time, the differential pressure between the front-side sealing cavity 62 and the rear-side sealing cavity 61 of the main drive seal 6 is 2.3 bar, and the error from the results of the previous two tests is 0.2 bar, meeting the error range required by the test.

[0050] If the pressure in the air tank simulation chamber 51 is 6 bar, and if it is necessary to reduce the pressure in the air tank simulation chamber 51 to 5 bar at this time, slowly open the stop valve 53. The gas in the air tank simulation chamber 51 will be discharged to the atmosphere through the single-acting ball valve three 52, the stop valve 53, and the silencer two 54. Observe the pressure gauge two 27 and close the stop valve 53 when the pressure drops to 5 bar.

[0051] A testing method for the main drive seal of a shield machine, which adopts the above-mentioned main drive seal testing system of the shield machine to test the performance of the main drive seal under different pressure levels. The specific steps are as follows:

[0052] Step 1: According to the experimental requirements, adjust the spring pre-tightening forces of the differential pressure regulating valve 34, the overpressure protection valve 41, and the safety valve 55;

[0053] Step 2: According to the experimental requirements, adjust the outlet pressure of the pressure calibration valve 23 to the test pressure required for the experiment, open all the ball valves, and connect the gas source to conduct the test experiment.

[0054] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A main drive seal test system for a shield machine, Characterized in that, It includes an air source (1), a pressure setting module (2), a differential pressure regulating module (3), a pressure relief module (4) and a soil and water pressure simulation module (5); one end of the pressure setting module (2) is connected to the soil and water pressure simulation module (5), and the other end is connected in parallel with the differential pressure regulating module (3) to the air source (1); the differential pressure regulating module (3) is connected to the rear seal cavity (61) of the main drive seal (6) for detecting and regulating the pressure of the rear seal cavity (61); the intake end of the pressure relief module (4) is connected to the rear seal cavity (61), and the control end of the pressure relief module (4) is connected to the soil and water pressure simulation module (5); the soil and water pressure simulation module (5) is connected to the front seal cavity (62) of the main drive seal (6) for detecting and regulating the pressure of the front seal cavity (62); The control end of the differential pressure regulating valve (34) of the differential pressure regulating module (3) is connected to the soil and water pressure simulation module (5) for realizing the pressure regulation of the rear seal cavity (61).

2. The main drive seal test system for a shield machine according to claim 1, Characterized in that, The pressure setting module (2) includes a ball valve one (21), a check valve (22), a pressure regulating valve (23), a pressure gauge one (24), a ball valve two (25), a single-acting ball valve one (26), a pressure gauge two (27) and a pressure sensor one (28) connected in sequence; for regulating the inlet air pressure of the soil and water pressure simulation module (5).

3. The main drive seal test system for a shield machine according to claim 2, Characterized in that, The differential pressure regulating module (3) includes a ball valve three (31), a single-acting ball valve two (32), a pressure gauge three (33), a differential pressure regulating valve (34) and a pressure sensor two (35) connected in sequence; the pressure sensor two (35) is connected to the rear seal cavity (61) for detecting and displaying the pressure of the rear seal cavity (61).

4. The main drive seal test system for a shield machine according to claim 3, Characterized in that, The pressure regulating valve (23) is a pressure reducing valve.

5. The main drive seal test system for a shield machine according to claim 4, Characterized in that, The pressure relief module (4) includes a overpressure protection valve (41) and a silencer one (42) connected in sequence; the intake end of the overpressure protection valve (41) is connected to the rear seal cavity (61); the control end of the overpressure protection valve (41) is connected to the soil and water pressure simulation module (5).

6. The main drive seal test system for a shield machine according to claim 5, Characterized in that, The soil and water pressure simulation module (5) includes an air tank simulation chamber (51), a single-acting ball valve three (52), a globe valve (53) and a silencer two (54) connected in sequence; the air tank simulation chamber (51) is connected to a safety valve (55) for preventing the air tank simulation chamber (51) from bulging.

7. The main drive seal test system for a shield machine according to claim 6, Characterized in that, The gas tank simulation chamber (51) is connected to the control ends of the differential pressure regulating valve (34) and the overpressure protection valve (41) through the fourth ball valve (56).

8. A main drive seal test system for a shield machine according to claim 7, characterized in that, the gas tank simulation chamber (51) is connected to the front seal cavity (62) through the fifth ball valve (57) to adjust the pressure of the front seal cavity (62) of the main drive seal (6).

9. A main drive seal test system for a shield machine according to claim 8, characterized in that, the safety valve (55) is a relief valve.

10. A main drive seal test method for a shield machine, which adopts a main drive seal test system as described in any one of claims 1 to 9 to test the performance of the main drive seal at different pressure levels. The specific steps are as follows: Step 1: Adjust the spring pre-tightening forces of the differential pressure regulating valve (34), the overpressure protection valve (41) and the safety valve (55) according to the experimental requirements; Step 2: Adjust the outlet pressure of the pressure regulating valve (23) to the test pressure required by the experiment according to the experimental requirements, open all the ball valves, and connect the gas source to conduct the test experiment.

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