Performance test system and method of shield tunneling machine water pressure monitoring device under water-soil combined load

Abstract

The invention discloses a performance test system and method for a water pressure monitoring device of a shield tunneling machine under a water-soil combined load. The system comprises a cylinder, a piston, a water pressure monitoring device interface, a first air compressor interface, a pore pressure monitoring interface, a gas-liquid conversion container interface, a gas-liquid conversion container, a water pressure monitoring device, a bracket and a flushing pump, a piston is arranged in the cylinder, a water pressure monitoring device is connected with the cylinder through a water pressure monitoring device connector, a first air compressor is connected with the cylinder through a first air compressor connector on the outer side of a top cover of the cylinder, and a micro osmometer is connected with the cylinder through a pore pressure monitoring connector on the side wall of the cylinder. The gas-liquid conversion container is connected with the cylinder through a gas-liquid conversion container connector in the side wall of the cylinder, the gas-liquid conversion container is further connected with the second air compressor, and the water pressure monitoring device is further connected with the flushing pump. The testing process and operation are simple, the result is reliable, and the method has great significance in monitoring the stratum water pressure near the shield body in the shield tunneling machine construction engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of performance testing of water pressure monitoring devices, and in particular to a performance testing system and method for a water pressure monitoring device of a shield machine under combined water and soil loads. Background Art

[0002] With the construction of urban subways and underwater river tunnels, slurry shield tunneling technology has been widely adopted. The formation water pressure during shield construction directly affects the settings of parameters such as incision pressure and grouting pressure, as well as the adjustment of the shield machine's sealing system. Therefore, real-time monitoring of formation water pressure during shield construction is crucial for safe construction.

[0003] To prevent friction and compression of the sensor by the ground during shield tunneling, water pressure monitoring devices on the shield are currently typically embedded. Chinese Patent CN116558696B discloses a water and soil pressure monitoring system and method for shield construction. This system is installed on the shield via a threaded connection from within the shield, with a filter device located at the junction between the monitoring device and the shield. However, because fine clay, coarse sand, gravel, and other soil particles may be distributed in the stratum, and slurry in the shield excavation chamber may flow into the stratum voids, the filter device may become clogged by fine soil or slurry particles. Furthermore, when the ground pressure in the stratum is excessive, soil may flow into the water pressure monitoring device, causing the water pressure monitoring device's pipe to become blocked by soil. This may result in poor testing results due to pipe clogging. Furthermore, the shield structure of the shield machine bears both the ground pressure and water pressure loads, placing higher demands on the safety and pressure resistance of the water pressure monitoring device's sealing performance. Therefore, before actual engineering application, how to test the pressure resistance, sealing, sensitivity, accuracy, anti-clogging performance of the water pressure monitoring device is an urgent problem that needs to be solved. Summary of the Invention

[0004] The purpose of the present invention is to provide a performance testing system and method for a water pressure monitoring device of a shield machine under combined water and soil loads, which can test the sensitivity, accuracy and long-term working stability of the water pressure monitoring device under water and soil pressure loads in different strata, and can test the clogging and flushing effect of the water pressure monitoring device in different media (mud, water and soil mixtures). The test operation is convenient and has high reliability.

[0005] The present invention adopts the following technical solution: a performance testing system for a shield machine water pressure monitoring device under combined water and soil loads, comprising:

[0006] Cylinder, piston, water pressure monitoring device interface, first air compressor interface, hole pressure monitoring interface, gas-liquid conversion container interface, gas-liquid conversion container, water pressure monitoring device, bracket and flushing pump.

[0007] The cylinder is fixed on the bracket; a piston is provided inside the cylinder, and the piston is close to the inner walls of both sides of the cylinder; the water pressure monitoring device interface is provided at the bottom of the cylinder, and one end of the water pressure monitoring device is connected to the cylinder through the water pressure monitoring device interface; a first air compressor interface is provided on the outside of the cylinder top cover, the first air compressor interface is connected to one end of the first metal conduit, and the other end of the first metal conduit is connected to the first air compressor; three pore pressure monitoring interfaces are provided on one side wall of the cylinder, and two pore pressure monitoring interfaces and a gas-liquid conversion container interface are provided on the other side wall of the cylinder, and the gas-liquid conversion container interface is located below the pore pressure monitoring interface; the micro osmometer is connected to the pore pressure monitoring interface; the gas-liquid conversion container interface is connected to one end of the gas-liquid conversion container through the second metal conduit, and the other end of the gas-liquid conversion container is connected to the second air compressor; the other end of the water pressure monitoring device is connected to the flushing pump through the third metal conduit.

[0008] Furthermore, the first air compressor interface is connected to one end of the first metal conduit through a threaded connection.

[0009] Furthermore, a cylindrical interface is provided below one side wall of the gas-liquid conversion container, and a second air compressor interface is provided above the other side wall of the gas-liquid conversion container.

[0010] The cylindrical interface is connected to the gas-liquid conversion container interface through a second metal conduit, and the second air compressor interface is connected to the second air compressor through a fourth metal conduit.

[0011] Furthermore, the water pressure monitoring device includes a shield shell interface, a ball valve, a four-way pipe and a water pressure sensor. The four-way pipe is arranged in the center of the water pressure monitoring device. The four-way pipe is respectively connected to one end of the first ball valve, one end of the second ball valve, one end of the third ball valve, and one end of the water pressure sensor. The other end of the first ball valve is connected to the pressure gauge, the other end of the second ball valve is connected to the flushing pump through the flushing interface, the other end of the third ball valve is threadedly connected to the inner wall of the water pressure monitoring device interface through the shield shell interface, and the other end of the water pressure sensor is connected to the data acquisition instrument through a data cable.

[0012] Furthermore, the cylinder is a hollow cylinder made of 304 stainless steel, with a diameter of 500 mm and a height of 600 mm.

[0013] Furthermore, the piston is an oblate cylinder with a thickness of 30 mm, and two flexible rubber rings with a diameter of 500 mm are wrapped around the outer circumference of the piston.

[0014] Furthermore, the interface of the water pressure monitoring device is a 2-inch ZG threaded hole, and a metal filter with a diameter of 2 inches is placed in the threaded hole.

[0015] Furthermore, the diameter of the gas-liquid conversion container interface is 5 mm.

[0016] The gas-liquid conversion container is made of 304 stainless steel.

[0017] The bracket is made of 304 stainless steel, with a height of 1000mm and a width of 550mm. The middle of the bracket top plate is hollow.

[0018] Furthermore, the power of the flushing pump is 750W and the head is 45m.

[0019] Furthermore, the present invention also proposes a method for testing a performance testing system of a shield machine water pressure monitoring device under combined water and soil loads, comprising:

[0020] (1) Test the sealing performance and pressure resistance of the water pressure monitoring device. The specific steps include:

[0021] Step 1: Close the valve connected to the gas-liquid conversion container interface and add water into the cylinder. Stop when the distance between the water surface and the top cover of the cylinder is 15 cm.

[0022] Step 2: Install the piston to the position just touching the water surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro osmometer and the water pressure monitoring device;

[0023] Step 3: Turn on the first air compressor and increase the injection pressure to 0.5 MPa, 0.6 MPa, 0.7 MPa, and 0.8 MPa in sequence. After each loading, let it stand for 1 hour, and record the readings of the micro-osmometer and the water pressure sensor in the water pressure monitoring device during each loading;

[0024] Step 4. Observe whether there is any water leakage at the interface of the water pressure monitoring device and the interface of the water pressure monitoring device itself; if there is water leakage at the water pressure monitoring device, it indicates that the sealing performance of the device is poor, and the water pressure when leakage occurs is the pressure resistance value of the device; if there is no water leakage at the interface of the water pressure monitoring device and the water pressure monitoring device when the pressure is loaded to 0.8MPa, it indicates that the sealing performance and pressure resistance of the device are excellent.

[0025] (2) Test the sensitivity, accuracy and stability of the water pressure monitoring device. The specific steps include:

[0026] Step 1: Add sand and soil material into the cylinder and saturate it with water; install the piston to the position where it just contacts the soil surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro osmometer and water pressure monitoring device;

[0027] Step 2: Turn on the first air compressor and increase the injection pressure to 0.5 MPa. This pressure pushes the piston to drain and consolidate the soil. When the micro-piezometer reading is 0, drainage is complete.

[0028] Step 3: Turn on the second air compressor and load the injected pressure to 0.1 MPa, and record the readings of the micro-osmometer, the water pressure sensor, and the pressure gauge in the water pressure monitoring device; load the injected pressure in a gradient of 0.1 MPa to 0.4 MPa, and then unload the injected pressure in a gradient of 0.1 MPa to 0.1 MPa, and record the readings of the water pressure sensor and the pressure gauge in the water pressure monitoring device during each loading and unloading;

[0029] Step 4: The pressure injected by the first air compressor is loaded to 1.0 MPa and 1.5 MPa respectively, and the pressure injected by the second air compressor is loaded and unloaded in a gradient of 0.1 MPa. The maximum loading value is the total load minus 0.1 MPa. The readings of the micro-osmometer, the water pressure sensor in the water pressure monitoring device, and the pressure gauge are recorded during each loading and unloading;

[0030] Step 5: Compare the readings of the water pressure sensor and the pressure gauge in the water pressure monitoring device in steps 3 and 4, respectively. If the difference is within 5 kPa, it indicates that the performance of the water pressure sensor in the water pressure monitoring device is correct. Now, compare the reading of the water pressure sensor in the water pressure monitoring device in step 4, the reading of the micro-osmometer, and the water head height difference between the water pressure sensor and the micro-osmometer. If the difference is within 5 kPa, it indicates that the accuracy of the water pressure monitoring device is excellent.

[0031] Step 6: When the formation water pressure load changes, if the reading of the water pressure sensor in the water pressure monitoring device in step 4 keeps changing synchronously with the reading of the micro-osmometer and the delay time is within 5 seconds, it indicates that the sensitivity of the water pressure monitoring device is excellent;

[0032] Step 7: Set a fixed ratio of soil pressure load and water pressure load combination, and maintain the water pressure monitoring device working continuously for 12 hours. If the accuracy of the water pressure monitoring device always meets the requirements in step 5 during this process, it indicates that the water pressure monitoring device has excellent stability performance.

[0033] (3) Test the clogging and flushing effect of the water pressure monitoring device in different media. The specific steps include:

[0034] Step 1: Add sand, pebbles, clay and mud materials of different particle sizes into the cylinder respectively and saturate them with water;

[0035] Step 2: Install the piston to the position just touching the soil surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro osmometer and the water pressure monitoring device;

[0036] Step 3: Turn on the first air compressor and increase the injection pressure to 0.5 MPa. This pressure pushes the piston to drain and consolidate the soil. When the micro-piezometer reading is 0, drainage is complete.

[0037] Step 4: Turn on the second air compressor and load the injected pressure to 0.1 MPa. Let it stand for 0.5 h and record the readings of the micro-osmometer, the water pressure sensor and the pressure gauge in the water pressure monitoring device; load the injected pressure to 0.4 MPa in a gradient of 0.1 MPa, and then unload the injected pressure to 0.1 MPa in a gradient of 0.1 MPa. Let it stand for 0.5 h after each loading and unloading;

[0038] Step 5: If the reading of the water pressure sensor in the water pressure monitoring device in step 4 is synchronized with the pressure change value of the second air compressor, and the difference is within 5 kPa, it indicates that the water pressure monitoring device is not blocked;

[0039] Step 6: Load the injection pressure of the first air compressor to 1.0 MPa and 1.5 MPa respectively, and repeat steps 3-4. If the reading of the water pressure sensor in the water pressure monitoring device is always synchronized with the pressure change value of the second air compressor, and the difference is within 5 kPa, it indicates that the water pressure monitoring device has excellent anti-clogging performance; otherwise, it indicates that the water pressure monitoring device is clogged, and the clogging time and the formation material causing the clogging are recorded;

[0040] Step 7. Open the flushing pump and the second ball valve to flush the water pressure monitoring device. After flushing for 5 minutes, close the second ball valve, add the actual water pressure value in the cylinder to the head height difference, and then compare it with the reading of the water pressure sensor in the water pressure monitoring device in step 6. If the difference is within 5kPa, stop flushing, indicating that the flushing effect is excellent, and record the flushing time; otherwise, continue flushing.

[0041] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0042] 1. The present invention can realistically simulate the ground environment of a shield machine under actual working conditions and can test the sealing performance and pressure resistance of a water pressure monitoring device under different ground water and soil pressure loads.

[0043] 2. The present invention can test the sensitivity, accuracy and long-term working stability of the water pressure monitoring device under water and soil pressure loads in different strata, and can test the clogging and flushing effect of the water pressure monitoring device in different media (mud, water-soil mixture).

[0044] 3. The present invention has reasonable settings, convenient test operation and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is the overall structural diagram of the system of the present invention.

[0046] Figure 2 It is a physical diagram of the system of the present invention.

[0047] Figure 3 It is a structural diagram of the gas-liquid conversion container of the present invention.

[0048] Figure 4 It is a structural diagram of the water pressure monitoring device of the present invention.

[0049] Figure numerals: cylinder 1, piston 2, water pressure monitoring device interface 3, first air compressor interface 4, hole pressure monitoring interface 5, gas-liquid conversion container interface 6, gas-liquid conversion container 7, cylinder interface 7-1, second air compressor interface 7-2, water pressure monitoring device 8, shield interface 8-1, ball valve 8-2, four-way pipe 8-3, water pressure sensor 8-4, bracket 9, flushing pump 10. DETAILED DESCRIPTION

[0050] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0051] To achieve the above objectives, the present invention proposes a performance testing system for a shield machine water pressure monitoring device under combined water and soil loads, such as Figure 1 、 2 As shown, including:

[0052] Cylinder 1, piston 2, water pressure monitoring device interface 3, first air compressor interface 4, pore pressure monitoring interface 5, gas-liquid conversion container interface 6, gas-liquid conversion container 7, water pressure monitoring device 8, bracket 9 and flushing pump 10.

[0053] The cylinder 1 is fixed to a bracket 9. A piston 2 is provided inside the cylinder 1, and the piston 2 is in close contact with the inner walls of the cylinder 1 on both sides. A water pressure monitoring device interface 3 is provided at the bottom of the cylinder 1, and one end of the water pressure monitoring device 8 is connected to the cylinder 1 through the water pressure monitoring device interface 3. A first air compressor interface 4 is provided on the outside of the top cover of the cylinder 1. The first air compressor interface 4 is connected to one end of a high-pressure-resistant first metal conduit via a threaded connection. The other end of the first metal conduit is connected to the first air compressor. The first air compressor interface 4 is used to provide a total stress load above the piston 2, and thus provide a total stress load inside the cylinder 1. Three pore pressure monitoring interfaces 5 are provided on one side wall of the cylinder 1, and two pore pressure monitoring interfaces 5 and a gas-liquid conversion container interface 6 are provided on the other side wall of the cylinder 1. The gas-liquid conversion container interface 6 is located below the pore pressure monitoring interface 5. A micro-osmometer is connected to the pore pressure monitoring interface 5 and is used to monitor the fluid pressure at different depths within the cylinder 1. The gas-liquid conversion container port 6, which serves as the fluid outlet in the cylinder 1 during the flushing process, has a diameter of 5 mm and is connected to one end of the gas-liquid conversion container 7 via a second metal conduit. The other end of the gas-liquid conversion container 7 is connected to the second air compressor. The other end of the water pressure monitoring device 8 is connected to the flushing pump 10 via a third metal conduit, using a flange connection.

[0054] Piston 2 is a flat cylinder with a diameter slightly less than 500mm and a thickness of 30mm. Two 500mm-diameter flexible rubber rings are wrapped around its circumference. Piston 2, enclosed by these rubber rings, is placed inside cylinder 1. Piston 2 divides the interior of cylinder 1 into an upper area and a lower area, sealed by the rubber rings. The lower area inside cylinder 1 is filled with soil, mud, water, or a mixture of these. Piston 2 is made of aircraft-grade aluminum and can withstand a maximum pressure of 5.0MPa.

[0055] like Figure 3 As shown, a cylindrical interface 7-1 is provided below one side wall of the gas-liquid conversion container 7, and a second air compressor interface 7-2 is provided above the other side wall of the gas-liquid conversion container 7.

[0056] Cylinder interface 7-1 is connected to gas-liquid conversion container interface 6 via a second metal conduit, while second air compressor interface 7-2 is connected to the second air compressor via a fourth metal conduit, thereby providing a constant hydraulic load. Gas-liquid conversion container 7 is used to transfer the air pressure from the second air compressor to the fluid pressure in the lower area of cylinder 1. When the water pressure monitoring device is flushed, the fluid in cylinder 1 flows through gas-liquid conversion container interface 6 into gas-liquid conversion container 7.

[0057] like Figure 4As shown, the water pressure monitoring device 8 includes a shield interface 8-1, a ball valve 8-2, a cross-piece 8-3, and a water pressure sensor 8-4. The cross-piece 8-3 is located at the center of the water pressure monitoring device 8 and is connected to one end of the first ball valve, one end of the second ball valve, one end of the third ball valve, and one end of the water pressure sensor 8-4. The other end of the first ball valve is connected to a pressure gauge, the other end of the second ball valve is connected to a flushing pump 10 via a flushing interface, and the other end of the third ball valve is threadedly connected to the inner wall of the water pressure monitoring device interface 3 via the shield interface 8-1. The other end of the water pressure sensor 8-4 is connected to a data acquisition device via a data cable for automatically reading water pressure monitoring data. The ball valve 8-2 is used to control the entry of water and mud and to flush the water pressure monitoring device interface 3 when it becomes clogged.

[0058] The cylinder 1 is a hollow cylinder made of 304 stainless steel, with a diameter of 500 mm and a height of 600 mm.

[0059] The interface 3 of the water pressure monitoring device is a 2-inch ZG threaded hole. A metal filter with a diameter of 2 inches is placed in the threaded hole to prevent solid particles in the cylinder 1 from entering the water pressure monitoring device.

[0060] The gas-liquid conversion container 7 is made of 304 stainless steel.

[0061] The bracket 9 is made of 304 stainless steel and is used to support and fix the cylinder 1. It has a height of 1000mm and a width of 550mm. The middle of the top plate of the bracket 9 is hollowed out for connecting the cylinder 1 and the water pressure monitoring device 8.

[0062] The flushing pump 10 is used for flushing when blockage occurs inside the water pressure monitoring device 8. The power of the flushing pump 10 is 750W and the lift is 45m.

[0063] To simulate the static field environment of a shield machine under actual operating conditions, an environment containing different types of stratum materials and capable of independently applying soil and water pressure loads was created. The space below the piston was filled with different types of stratum materials and saturated. The first air compressor injected a constant total pressure load P1 into the cylinder through the first air compressor interface, and the second air compressor injected a constant water pressure load P2 into the cylinder through the second air compressor interface. Based on the Terzaghi effective stress principle, the actual force on the soil is P3 = P1 - P2, which satisfies the conditions for independently applying the soil load P3 and water pressure load P2.

[0064] In order to test the sealing performance and pressure resistance of the water pressure monitoring device under different loads, the following operations are performed using the performance testing system for the shield machine water pressure monitoring device under water-soil combined load proposed in the present invention:

[0065] Step 1: Close the valve connected to the gas-liquid conversion container interface, add water into the cylinder, and stop when the distance between the water surface and the top cover of the cylinder is 15 cm.

[0066] Step 2: Install the piston to a position just in contact with the water surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro osmometer and the water pressure monitoring device.

[0067] Step 3: Turn on the first air compressor and load the injection pressure to 0.5 MPa, 0.6 MPa, 0.7 MPa and 0.8 MPa in sequence. Let it stand for 1 hour after each loading, and record the readings of the micro osmometer and the water pressure sensor in the water pressure monitoring device during each loading.

[0068] Step 4. Observe whether there is any water leakage at the interface of the water pressure monitoring device and the interface of the water pressure monitoring device itself; if there is water leakage at the water pressure monitoring device, it indicates that the sealing performance of the device is poor. The water pressure when leakage occurs is the pressure resistance value of the device, and the sealing measures of the device need to be processed or improved; if there is no water leakage at the interface of the water pressure monitoring device and the water pressure monitoring device when the pressure is loaded to 0.8MPa, it indicates that the sealing performance and pressure resistance of the device are good.

[0069] Step 5: Close the valve connected to the gas-liquid conversion container interface and add mud into the cylinder. Stop when the distance between the mud surface and the cylinder cover is 15 cm. Repeat steps 2-4 to obtain the sealing performance and pressure resistance performance of the water pressure monitoring device.

[0070] In order to test the sensitivity, accuracy, and long-term working stability of the water pressure monitoring device under different water and soil loads, the following operations are performed using the performance testing system for the shield machine water pressure monitoring device under combined water and soil loads proposed in the present invention:

[0071] Step 1: Add sand and soil material into the cylinder and saturate it with water; install the piston to a position that just contacts the soil surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro piezometer and the water pressure monitoring device.

[0072] Step 2: Turn on the first air compressor and load the injection pressure to 0.5 MPa. This pressure pushes the piston to drain and consolidate the soil. When the reading of the micro piezometer is 0, it means that the drainage is completed.

[0073] Step 3. Turn on the second air compressor and load the injected pressure to 0.1 MPa, and record the readings of the micro-osmometer, the water pressure sensor and the pressure gauge in the water pressure monitoring device; after the readings stabilize, load the injected pressure to 0.4 MPa in a gradient of 0.1 MPa, and then unload the injected pressure to 0.1 MPa in a gradient of 0.1 MPa, and record the readings of the water pressure sensor and the pressure gauge in the water pressure monitoring device during each loading and unloading.

[0074] Step 4: Load the pressure injected by the first air compressor to 1.0 MPa and 1.5 MPa respectively, and load and unload the pressure injected by the second air compressor in a gradient of 0.1 MPa. The maximum loading value is the total load minus 0.1 MPa. Record the readings of the micro-osmometer, water pressure sensor and pressure gauge in the water pressure monitoring device during each loading and unloading.

[0075] Step 5. Compare the readings of the water pressure sensor and the pressure gauge in the water pressure monitoring device in steps 3 and 4 respectively. If the difference is within 5kPa, it indicates that the performance of the water pressure sensor in the water pressure monitoring device is intact. At this time, compare the reading of the water pressure sensor in the water pressure monitoring device in step 4, the reading of the micro osmometer, and the head height difference between the water pressure sensor and the micro osmometer. If the difference is within 5kPa, it indicates that the accuracy of the water pressure monitoring device is excellent.

[0076] Step 6: When the formation water pressure load changes, if the reading of the water pressure sensor in the water pressure monitoring device in step 4 keeps changing synchronously with the reading of the micro osmometer and the delay time is within 5s, it indicates that the sensitivity of the water pressure monitoring device is reliable.

[0077] Step 7: Set a fixed ratio of soil pressure load and water pressure load combination, and maintain the water pressure monitoring device working continuously for 12 hours. If the accuracy of the water pressure monitoring device always meets the requirements in step 5 during this process, it indicates that the long-term stability of the water pressure monitoring device is reliable.

[0078] Step 8: Replace the sand material added in step 1 with clay, pebbles, and mud respectively, and repeat steps 1-7 to obtain the sensitivity, accuracy, and long-term working stability of the water pressure monitoring device.

[0079] In order to test the clogging and flushing effect of the water pressure monitoring device in different media (mud, water-soil mixture), the following operations were performed using the performance testing system of the shield machine water pressure monitoring device under water-soil combined load proposed in the present invention:

[0080] Step 1: Add sand, pebbles, clay and mud materials with different particle sizes into the cylinder respectively, and saturate them with water.

[0081] Step 2: Install the piston to the position where it just contacts the soil surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro piezometer and the water pressure monitoring device.

[0082] Step 3: Turn on the first air compressor and load the injection pressure to 0.5 MPa. This pressure pushes the piston to drain and consolidate the soil. When the reading of the micro piezometer is 0, it means that the drainage is completed.

[0083] Step 4: Turn on the second air compressor, load the injected pressure to 0.1 MPa, let it stand for 0.5 h, and record the readings of the micro-osmometer, the water pressure sensor and the pressure gauge in the water pressure monitoring device; load the injected pressure to 0.4 MPa in a gradient of 0.1 MPa, and then unload the injected pressure to 0.1 MPa in a gradient of 0.1 MPa. Let it stand for 0.5 h after each loading and unloading.

[0084] Step 5: If the reading of the water pressure sensor in the water pressure monitoring device in step 4 is synchronized with the pressure change value of the second air compressor, and the difference is within 5 kPa, it indicates that the water pressure monitoring device is not blocked.

[0085] Step 6. Load the pressure injected by the first air compressor to 1.0MPa and 1.5MPa respectively, and repeat steps 3-4. If the reading of the water pressure sensor in the water pressure monitoring device is always synchronized with the pressure change value of the second air compressor, and the difference is within 5kPa, it indicates that the water pressure monitoring device has good anti-clogging performance; otherwise, it indicates that the water pressure monitoring device is clogged, and the clogged time and the formation material where the clogged occurred are recorded.

[0086] Step 7. Open the flushing pump and the second ball valve to flush the water pressure monitoring device. After flushing for 5 minutes, close the second ball valve, add the actual water pressure value in the cylinder to the head height difference, and then compare it with the reading of the water pressure sensor in the water pressure monitoring device in step 6. If the difference is within 5kPa, stop flushing, indicating that the flushing effect is excellent, and record the flushing time; otherwise, continue flushing.

[0087] Specific implementation results: Under high water pressure conditions of 1.25MPa, during the application of the test load, the shield water pressure monitoring device did not leak water, had good sealing, could maintain normal working condition, and had good pressure resistance; as the formation water pressure changed step by step, the device responded sensitively and the reading error was less than 3%; in tests of high-viscosity mud group, clay group, sand group and pebble group, the readings of the device's water pressure sensor and piezometer changed synchronously with time, and the average error between the two was about 3%, indicating that the device did not have clogging problems and had good anti-clogging properties.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A performance testing system for a shield machine water pressure monitoring device under combined water and soil loads, characterized in that: include: Cylinder (1), piston (2), water pressure monitoring device interface (3), first air compressor interface (4), pore pressure monitoring interface (5), gas-liquid conversion container interface (6), gas-liquid conversion container (7), water pressure monitoring device (8), bracket (9) and flushing pump (10); The cylinder (1) is fixed on the bracket (9); a piston (2) is provided inside the cylinder (1), and the piston (2) is closely attached to the inner walls of both sides of the cylinder (1); a water pressure monitoring device interface (3) is provided at the bottom of the cylinder (1), and one end of the water pressure monitoring device (8) is connected to the cylinder (1) through the water pressure monitoring device interface (3); a first air compressor interface (4) is provided on the outside of the top cover of the cylinder (1), and the first air compressor interface (4) is connected to one end of the first metal conduit, and the other end of the first metal conduit is connected to the first air compressor; one side of the cylinder (1) Three pore pressure monitoring interfaces (5) are provided on the wall, two pore pressure monitoring interfaces (5) and a gas-liquid conversion container interface (6) are provided on the other side wall of the cylindrical body (1), and the gas-liquid conversion container interface (6) is located below the pore pressure monitoring interface (5); the micro-osmometer is connected to the pore pressure monitoring interface (5); the gas-liquid conversion container interface (6) is connected to one end of the gas-liquid conversion container (7) through a second metal conduit, and the other end of the gas-liquid conversion container (7) is connected to the second air compressor; the other end of the water pressure monitoring device (8) is connected to the flushing pump (10) through a third metal conduit.

2. The performance testing system for the shield machine water pressure monitoring device under combined water and soil loads according to claim 1 is characterized in that: The first air compressor interface (4) is connected to one end of the first metal conduit by means of a threaded connection.

3. The performance testing system for the shield machine water pressure monitoring device under combined water and soil loads according to claim 1 is characterized in that: A cylindrical interface (7-1) is provided below one side wall of the gas-liquid conversion container (7), and a second air compressor interface (7-2) is provided above the other side wall of the gas-liquid conversion container (7); The cylindrical body interface (7-1) is connected to the gas-liquid conversion container interface (6) via a second metal conduit, and the second air compressor interface (7-2) is connected to the second air compressor via a fourth metal conduit.

4. The performance testing system for a shield machine water pressure monitoring device under combined water and soil loads according to claim 1 is characterized in that: The water pressure monitoring device (8) comprises a shield interface (8-1), a ball valve (8-2), a four-way pipe (8-3) and a water pressure sensor (8-4). The four-way pipe (8-3) is arranged at the center of the water pressure monitoring device (8). The four-way pipe (8-3) is respectively connected to one end of the first ball valve, one end of the second ball valve, one end of the third ball valve and one end of the water pressure sensor (8-4). The other end of the first ball valve is connected to a pressure gauge. The other end of the second ball valve is connected to a flushing pump (10) via a flushing interface. The other end of the third ball valve is threadedly connected to the inner wall of the water pressure monitoring device interface (3) via the shield interface (8-1). The other end of the water pressure sensor (8-4) is connected to a data acquisition instrument via a data line.

5. The performance testing system for the shield machine water pressure monitoring device under combined water and soil loads according to claim 1 is characterized in that: The cylinder (1) is a hollow cylinder made of 304 stainless steel, with a diameter of 500 mm and a height of 600 mm.

6. The performance testing system for a shield machine water pressure monitoring device under combined water and soil loads according to claim 1 is characterized in that: The piston (2) is a flat cylinder with a thickness of 30 mm. Two flexible rubber rings with a diameter of 500 mm are wound around the outer circumference of the piston (2).

7. The performance testing system for a shield machine water pressure monitoring device under combined water and soil loads according to claim 1 is characterized in that: The interface (3) of the water pressure monitoring device is a 2-inch ZG threaded hole, and a metal filter with a diameter of 2 inches is placed in the threaded hole.

8. The performance testing system for a shield machine water pressure monitoring device under combined water and soil loads according to claim 1 is characterized in that: The diameter of the gas-liquid conversion container interface (6) is 5 mm; The gas-liquid conversion container (7) is made of 304 stainless steel; The bracket (9) is made of 304 stainless steel, has a height of 1000 mm and a width of 550 mm, and the middle of the top plate of the bracket (9) is hollow.

9. The performance testing system for a shield machine water pressure monitoring device under combined water and soil loads according to claim 1, characterized in that: The power of the flushing pump (10) is 750W and the head is 45m.

10. A testing method for a performance testing system of a shield machine water pressure monitoring device under combined water and soil loads as claimed in any one of claims 1 to 9, characterized in that: include: (1) Test the sealing performance and pressure resistance of the water pressure monitoring device. The specific steps include: Step 1: Close the valve connected to the gas-liquid conversion container interface and add water into the cylinder. Stop when the distance between the water surface and the top cover of the cylinder is 15 cm. Step 2: Install the piston to the position just touching the water surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro osmometer and the water pressure monitoring device; Step 3: Turn on the first air compressor and increase the injection pressure to 0.5 MPa, 0.6 MPa, 0.7 MPa, and 0.8 MPa in sequence. After each loading, let it stand for 1 hour and record the readings of the water pressure sensor and micro-osmometer in the water pressure monitoring device during each loading. Step 4. Observe the interface of the water pressure monitoring device for water leakage. If there is water leakage, it indicates that the sealing performance of the device is poor. The water pressure when leakage occurs is the pressure resistance value of the device. If there is no water leakage when the pressure is loaded to 0.8MPa, it indicates that the sealing performance and pressure resistance of the device are excellent. (2) Test the sensitivity, accuracy and stability of the water pressure monitoring device. The specific steps include: Step 1: Add sand and soil material into the cylinder and saturate it with water; install the piston to the position where it just contacts the soil surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro osmometer and water pressure monitoring device; Step 2: Turn on the first air compressor and increase the injection pressure to 0.5 MPa. This pressure pushes the piston to drain and consolidate the soil. When the micro-piezometer reading is 0, drainage is complete. Step 3: Turn on the second air compressor and load the injected pressure to 0.1 MPa, and record the readings of the water pressure sensor, micro-osmometer, and pressure gauge in the water pressure monitoring device; load the injected pressure to 0.4 MPa in a gradient of 0.1 MPa, and then unload the injected pressure to 0.1 MPa in a gradient of 0.1 MPa, and record the readings of the water pressure sensor and pressure gauge in the water pressure monitoring device during each loading and unloading; Step 4: The pressure injected by the first air compressor is loaded to 1.0 MPa and 1.5 MPa respectively, and the pressure injected by the second air compressor is loaded and unloaded in sequence with a gradient of 0.1 MPa. The maximum loading value is the total load minus 0.1 MPa. The readings of the water pressure sensor, micro osmometer, and pressure gauge in the water pressure monitoring device are recorded during each loading and unloading; Step 5: Compare the readings of the water pressure sensor and the pressure gauge in the water pressure monitoring device in steps 3 and 4, respectively. If the difference is within 5 kPa, it indicates that the performance of the water pressure sensor in the water pressure monitoring device is correct. Now, compare the reading of the water pressure sensor in the water pressure monitoring device in step 4, the reading of the micro-osmometer, and the water head height difference between the water pressure sensor and the micro-osmometer. If the difference is within 5 kPa, it indicates that the accuracy of the water pressure monitoring device is excellent. Step 6: When the formation water pressure load changes, if the reading of the water pressure sensor in the water pressure monitoring device in step 4 keeps changing synchronously with the reading of the micro-osmometer and the delay time is within 5 seconds, it indicates that the sensitivity of the water pressure monitoring device is excellent; Step 7: Set a fixed ratio of earth pressure load and water pressure load combination, and maintain the water pressure monitoring device in continuous operation for 12 hours. If the accuracy of the water pressure monitoring device always meets the requirements of step 5 during this process, it indicates that the water pressure monitoring device has excellent stability performance; (3) Test the clogging and flushing effect of the water pressure monitoring device in different media. The specific steps include: Step 1: Add sand, pebbles, clay and mud materials of different particle sizes into the cylinder respectively and saturate them with water; Step 2: Install the piston to the position just touching the soil surface, cover the top cover of the cylinder, and seal it with bolts and rubber rings; turn on the sensor collector of the micro osmometer and the water pressure monitoring device; Step 3: Turn on the first air compressor and increase the injection pressure to 0.5 MPa. This pressure pushes the piston to drain and consolidate the soil. When the micro-piezometer reading is 0, drainage is complete. Step 4: Turn on the second air compressor and load the injected pressure to 0.1 MPa. Let it stand for 0.5 h and record the readings of the water pressure sensor, micro-osmometer and pressure gauge in the water pressure monitoring device; load the injected pressure to 0.4 MPa in a gradient of 0.1 MPa, and then unload the injected pressure to 0.1 MPa in a gradient of 0.1 MPa. Let it stand for 0.5 h after each loading and unloading; Step 5: If the reading of the water pressure sensor in the water pressure monitoring device in step 4 is synchronized with the pressure change value of the second air compressor, and the difference is within 5 kPa, it indicates that the water pressure monitoring device is not blocked; Step 6: Load the injection pressure of the first air compressor to 1.0 MPa and 1.5 MPa respectively, and repeat steps 3-4. If the reading of the water pressure sensor in the water pressure monitoring device is always synchronized with the pressure change value of the second air compressor, and the difference is within 5 kPa, it indicates that the water pressure monitoring device has excellent anti-clogging performance; otherwise, it indicates that the water pressure monitoring device is clogged, and the clogging time and the formation material causing the clogging are recorded; Step 7. Open the flushing pump and the second ball valve to flush the water pressure monitoring device. After flushing for 5 minutes, close the second ball valve, add the actual water pressure value in the cylinder to the head height difference, and then compare it with the reading of the water pressure sensor in the water pressure monitoring device in step 6. If the difference is within 5kPa, stop flushing, indicating that the flushing effect is excellent, and record the flushing time; otherwise, continue flushing.

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