Performance Testing Device and Testing Method for Water Pressure Sensors under the Tunneling State of a Simulated Shield Machine

Abstract

The invention discloses a performance test device and a test method for a water pressure sensor under the tunneling state of a shield machine, belonging to the technical field of water pressure measurement. The device includes: a shield shell arranged in the device, a sensor sealing cabin installed in the shield shell, and a rotating mechanism drivingly connected to the shield shell. By using this device for testing, the monitoring process of the water pressure sensor on the shield body under the tunneling state of the shield machine can be truly simulated; the change rules of the pore water pressure monitored by the water pressure sensor on the shield body under the tunneling state of the shield machine, as well as the friction and siltation conditions, can be accurately measured.

Description

Technical Field

[0001] The present invention belongs to the technical field of water pressure measurement, and particularly relates to a performance test device and a test method for a water pressure sensor under the tunneling state of a simulated shield machine. Background Art

[0002] With the large-scale construction of urban subways, water diversion tunnels, especially large cross-river and cross-sea tunnels in China, the application of slurry shield tunnel technology is becoming more and more extensive. The construction water pressure in slurry shield tunnel construction is one of the main setting bases for construction parameters such as the slurry pressure in the excavation chamber of the shield machine and the backfill grouting pressure. Therefore, real-time detection of the construction water pressure value during shield tunneling is of great significance for guiding shield tunnel construction.

[0003] In existing research, most scholars only monitor the water pressure on the segments of the shield tunnel and do not monitor the external water pressure of the shield machine. At present, existing research has designed a water pressure sensor arranged on the shield body to monitor the external water pressure received by the shield body, but the working and safety performance of the water pressure sensor in actual shield projects remains to be verified. In the shield body structure, the cutter head of the shield machine is slightly larger than the diameter of the shield shell. After shield excavation, there is a certain gap between the shield shell and the soil body. When the strength of the soil body outside the shield shell is lower than the external force it receives, the soil body is damaged and moves towards the shield shell, and the soil collapse and mixed slurry will fill the gap, which is likely to cause blockage of the water pressure sensor. Under different geological conditions, the environmental influence on the sensors installed on the outer shell of the shield machine can be divided into the following two types: 1. In fractured strata, gravel strata, and coarse sand strata, the friction, collision impact, and extrusion of irregular gravel, gravel, and coarse sand on the sensor cause wear to the sensor; 2. Blockage of fine powders such as rock powder, fine sand, and clay, and viscous microparticles in the excavation chamber slurry wrapping on the surface of the sensor. Therefore, it is necessary to consider the influence of formation friction and clay blockage on the accuracy and sensitivity of the water pressure sensor arranged on the shield body. Summary of the Invention

[0004] The present invention provides a performance test device and a test method for a water pressure sensor under the tunneling state of a simulated shield machine to solve the technical problems existing in the above background art.

[0005] The present invention adopts the following technical solutions: A performance test device for a water pressure sensor under the tunneling state of a simulated shield machine, including a mounting base; further including:

[0006] A rotating mechanism, arranged inside the mounting base;

[0007] An outer cylinder, arranged on the mounting base; the inside of the outer cylinder is a hollow structure, and an air compressor interface is provided on its side surface;

[0008] A shield housing, located within the hollow structure and drivingly connected to the rotating mechanism; a predetermined distance is left between the shield housing and the outer cylinder to form a filling chamber;

[0009] A sensor sealed cabin, detachably installed within the shield housing; a water pressure sensor is provided within the sensor sealed cabin;

[0010] A slip ring, provided at the top of the shield housing and located at the rotation center; the slip ring is used to simulate the tunneling state of the water pressure sensor with the shield body in the formation.

[0011] In a further embodiment, the sensor sealed cabin includes:

[0012] A housing, having a hollow structure inside; both ends of the housing are open structures, namely a connection end and a hatch end respectively;

[0013] A sandwich sealing plate, fixedly installed along the radial direction at the connection end; the sandwich sealing plate is configured to fix the water pressure sensor; the power line and data line of the water pressure sensor are led out through the hatch end, and the connection end is threadedly connected to the shield housing.

[0014] In a further embodiment, the rotating mechanism includes:

[0015] A stepper motor, installed within the mounting base;

[0016] A coupling, drivingly connected to the output shaft of the stepper motor; the coupling is drivingly connected to the shield housing.

[0017] In a further embodiment, the slip ring includes:

[0018] A rotor, connected to the shield housing;

[0019] A stator, axially passing through the rotor movably; the stator is fixedly connected relative to the rotor, and a predetermined gap is left between the stator and the rotor to form an annular cavity, and the annular cavity is configured to lead out the power line and data line.

[0020] In a further embodiment, the sandwich sealing plate includes: two layers of plexiglass plates and a geotextile disposed between the two layers of plexiglass plates; wherein, the plexiglass plates are punched with flower holes.

[0021] A test method for simulating the performance of a water pressure sensor during the tunneling state of a shield machine, using the test device for simulating the performance of a water pressure sensor during the tunneling state of a shield machine as described above, and the following steps are all tested during rotation:

[0022] Step 1. Connect the test device to the air compressor through the air compressor interface. The air compressor is connected to the outer cylinder, and a water pressure sensor is installed on the outer cylinder. After installation, first check the airtightness of the interface and the tightness of the sensor sealed cabin: judge whether the interface and the sensor sealed cabin are leaking by observing whether there is liquid leakage at the interface, and judge whether the sensor performance test device is leaking by observing whether the water pressure monitoring data measured by the sensor is consistent with the air compressor data;

[0023] Step 2. The outer cylinder is filled with pure water, the water pressure sensor is installed on the outer cylinder, the air compressor is connected to the outer cylinder, set the initial pressure value in the air compressor, and gradually increase it to the pressure threshold P in accordance with the gradient of the pressure difference ΔP; each time the pressure difference ΔP is increased, synchronously obtain the response time of the water pressure sensor , where n is the number of times the pressure difference ΔP is increased; when the pressure in the air compressor reaches the pressure threshold, obtain the water pressure monitoring data under the pure water condition, and record the reading of the water pressure sensor as P1;

[0024] Step 3. Inject mud into the outer cylinder, set the initial pressure value in the air compressor, and gradually increase it to the pressure threshold P in accordance with the gradient of the pressure difference ΔP; each time the pressure difference ΔP is increased, synchronously obtain the response time of the water pressure sensor , where n is the number of times the pressure difference ΔP is increased; when the pressure in the air compressor reaches the pressure threshold, obtain the water pressure monitoring data under the mud condition, and record the reading of the water pressure sensor as P2; Compare and analyze the readings P1 and P2 of the water pressure sensor under the same pressure respectively to judge whether the water pressure sensor is blocked; Compare the sensor stabilization time after the air compressor is pressurized to the specified pressure to judge the sensitivity performance of the water pressure sensing device;

[0025] Step 4. Arbitrarily pressurize with the air compressor and obtain the pressurization value , simulate different water pressure conditions that may occur during the shield tunneling excavation process, and at the same time obtain the current reading P3 of the water pressure sensor;

[0026] Step 5. After standing for 24h and 48h respectively, repeat Steps 2 to 3 to obtain the water pressure sensor reading P4, and compare and analyze the water pressure sensor data P3 and P4 under the same pressure in turn to judge whether the water pressure sensor is blocked after standing for the predetermined time; Obtain the detection result of the sensor sealed cabin based on the analysis data, and execute the corresponding improvement measures according to the detection result.

[0027] In a further embodiment, the analysis process of the detection result is as follows:

[0028] When there is liquid seepage at the device interface or inside the sensor sealed cabin, it indicates that there is a water leakage problem at the device interface of the sensor performance testing device or in the sensor sealed cabin; when the air compressor cannot pressurize to the specified pressure, it indicates that there is an air leakage problem in the sensor performance testing device.

[0029] There is no water leakage or air leakage at the device interface, and when the water pressure monitoring data of the sensor and the data of the air compressor change synchronously over time, if the two data are equal, it indicates that the sealing performance, sensitivity, and accuracy of the entire sensor testing device are good, and it is not blocked; if the two data are not equal, then the sealing performance and sensitivity of the testing device are good, but the accuracy is lacking, and there is a blockage problem.

[0030] There is no water leakage or air leakage at the device interface, and the water pressure monitoring data of the sensor and the data of the air compressor do not change synchronously over time. If the two data are equal, it indicates that the sealing performance of the entire sensor testing device is good, the accuracy is accurate, but the sensitivity is lacking, or there may be a problem with slow water pressure transmission; if the two data are not equal, it indicates that the sealing performance and sensitivity of the testing device are good, the accuracy is lacking, and there is a blockage problem; there is no water leakage or air leakage at the device interface, and when the sensor cannot measure the water pressure monitoring data, it indicates that there is a problem with the sensor.

[0031] In a further embodiment, the improvement measures include: increasing the sealing performance of the device interface, replacing the sensor, replacing the geotextile, or checking the working state of the water pressure sensor.

[0032] Advantages of the present invention: A. It can truly simulate the monitoring process of the water pressure sensor on the shield body during the tunneling state of the shield machine.

[0033] B. It can accurately measure the change law, friction, and blockage situation of the pore water pressure monitored by the water pressure sensor on the shield body during the tunneling state of the shield machine.

[0034] C. The system is reasonably set up, the test operation is convenient, the cost is low, and it has high reliability. Description of the Drawings

[0035] Figure 1 It is a schematic diagram of the water pressure sensor performance testing device.

[0036] Figure 2 It is a schematic diagram of the structure of the sensor sealed cabin.

[0037] Figure 3 It is a schematic diagram of the structure of the slip ring.

[0038] Figure 4 It is a flowchart of the testing method for the performance of the water pressure sensor.

[0039] Figures 1 to 3The markings in the figure are: outer cylinder 1, air compressor interface 2, filling chamber 3, slip ring 4, rotating mechanism, sensor sealing cabin 6, rotor 4-1, stator 4-2, shield shell 5-1, coupling 5-2, stepper motor 5-3, mounting base 5-4, plexiglass plate 6-1, geotextile 6-2, water pressure sensor 6-3, and outer shell 6-4. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Example

[0041] like Figure 1 As shown, a performance test device for a water pressure sensor 6-3 simulating a shield machine excavation state includes a mounting base 5-4. The mounting base 5-4 is used to support the overall rotating system, specifically: an outer cylinder 1 is provided on the mounting base 5-4, wherein the interior of the outer cylinder 1 is a hollow structure, and an air compressor interface 2 is provided on the side thereof. Furthermore, the outer cylinder 1 in the present embodiment is a hollow cylinder, and the cylinder is selected mainly because of its good sealing performance, while reducing the size of the device, saving test costs and materials. The air compressor interface 2 is a pneumatic air pipe quick connector, which is used to achieve the connection between the outer cylinder 1 and the air compressor.

[0042] It also includes: a shield shell 5-1 arranged in the outer cylinder 1, and the shield shell 5-1 is connected to the rotating mechanism. It should be noted that a predetermined distance is left between the shield shell 5-1 and the outer cylinder 1 to form a filling chamber 3. The predetermined distance in this embodiment is 1-2 cm, and the formed filling chamber 3 is filled with a mixture of stratum soil and mud. Among them, the soil and mud mixture is a mixture of sand, bentonite, CMC and water.

[0043] A sensor sealed cabin 6 is installed in the shield shell 5-1, and a water pressure sensor 6-3 is arranged in the sensor sealed cabin 6. A slip ring 4 is arranged at the top of the shield shell 5-1 and at the rotation center, and the slip ring 4 is used to simulate the excavation state of the water pressure sensor 6-3 in the stratum with the shield body.

[0044] Combination Figure 2, the sensor sealed cabin 6 includes: a housing 6-4 with a hollow structure inside, and both ends of the housing 6-4 are open structures, namely a connection end and a hatch end. A sandwich sealing plate is fixedly arranged along the radial direction at the connection end, and the sandwich sealing plate is arranged to fix the water pressure sensor 6-3. In this embodiment, the power line and data line of the water pressure sensor 6-3 are led out through the hatch end, and the connection end is threadedly connected to the shield housing 5-1. Among them, the sandwich sealing plate includes: two layers of organic glass plates 6-1 and a geotextile 6-2 arranged between the two layers of organic glass plates 6-1, which is used to filter mud or formation materials to prevent particle blockage of the sensor; among them, the organic glass plate 6-1 is punched with flower holes for water permeability. The housing 6-4 is made of anti-corrosion steel.

[0045] In a further embodiment, a rotating mechanism is arranged in the mounting base 5-4, including: a stepping motor 5-3 fixed in the mounting base 5-4. The stepping motor 5-3 in this embodiment is a 130 stepping motor 5-3, and its rotational speed range is 0-600 rpm. The specific rotational speed is adjusted according to the required tunneling speed during the tunneling of different shield machines. The output shaft of the stepping motor 5-3 is connected with a coupling 5-2, and the coupling 5-2 is drivingly connected to the shield housing 5-1. The shield housing 5-1 is driven to rotate by itself through the stepping motor 5-3.

[0046] In a further embodiment, the slip ring 4 includes: a rotor 4-1 connected to the shield housing 5-1, and a stator 4-2 axially passing through the rotor 4-1. That is, the rotor 4-1 rotates with the shield housing 5-1, the stator 4-2 is fixedly connected relative to the rotor 4-1, and a predetermined gap is left between the stator 4-2 and the rotor 4-1 to form an annular cavity, and the annular cavity is arranged to lead out the power line and data line.

[0047] In this embodiment, the shield housing 5-1, the soil container, the sensor sealed cabin 6, and the mounting support are all made of special anti-corrosion steel and can withstand a maximum pressure of 5.0 MPa.

[0048] The test principle of this device is as follows: The rotation of the stepping motor 5-3 drives the shield housing 5-1 and the sensor to rotate through the coupling, realizing a true simulation of the working state of the sensor during the tunneling of the shield machine.

[0049] By filling the soil container with a mixture of formation soil and mud, the working environment of the sensor during the tunneling of the shield machine is simulated. Embodiment

[0050] In order to accurately measure the change law, friction and blockage conditions of the pore water pressure monitored by the water pressure sensor on the shield body during the tunneling of the shield machine, a performance test device for simulating the water pressure sensor during the tunneling of the shield machine in this embodiment is used. As Figure 4As shown, it includes the following steps (all these steps are tested during rotation):

[0051] Step 1: Connect the test device to the air compressor through the air compressor interface. The air compressor is connected to the outer cylinder, and a water pressure sensor is installed on the outer cylinder. After installation, first check the airtightness of the interface and the tightness of the sensor seal chamber: judge whether the interface and the sensor seal chamber are leaking by observing whether there is liquid leakage at the interface, and judge whether the sensor performance test device is leaking by observing whether the water pressure monitoring data measured by the sensor is consistent with the air compressor data.

[0052] Step 2: The outer cylinder is filled with pure water, the water pressure sensor is installed on the outer cylinder, and the air compressor is connected to the outer cylinder. Set the initial pressure value in the air compressor, and gradually increase it to the pressure threshold P according to the gradient of the pressure difference ΔP; each time the pressure difference ΔP is increased, synchronously obtain the response time T of the water pressure sensor n , where n is the number of times the pressure difference ΔP is increased; when the pressure in the air compressor reaches the pressure threshold, obtain the water pressure monitoring data under the pure water condition, and record the reading of the water pressure sensor as P1;

[0053] Step 3: Inject mud into the outer cylinder, set the initial pressure value in the air compressor, and gradually increase it to the pressure threshold P according to the gradient of the pressure difference ΔP; each time the pressure difference ΔP is increased, synchronously obtain the response time T of the water pressure sensor n , where n is the number of times the pressure difference ΔP is increased; when the pressure in the air compressor reaches the pressure threshold, obtain the water pressure monitoring data under the mud condition, and record the reading of the water pressure sensor as P2; Compare and analyze the readings P1 and P2 of the water pressure sensor under the same pressure to judge whether the water pressure sensor is blocked; Compare the sensor stabilization time after the air compressor is pressurized to the specified pressure to judge the sensitivity performance of the water pressure sensing device;

[0054] Step 4: Arbitrarily pressurize with the air compressor and obtain the pressurization value , simulate different water pressure conditions that may occur during the shield tunneling excavation process, and at the same time obtain the current reading P3 of the water pressure sensor;

[0055] Step 5: After standing for 24h and 48h respectively, repeat steps 2 to 3 to obtain the water pressure sensor reading P4, and compare and analyze the water pressure sensor data P3 and P4 under the same pressure in turn to judge whether the water pressure sensor is blocked after standing for a certain period of time; Obtain the detection result of the sensor seal chamber based on the analysis data, and execute the corresponding improvement measures according to the detection result.

[0056] During the experiment, the water pressure data monitored by the sensor will be obtained. Compare and analyze the water pressure data measured by the sensor with the data of the air compressor pressurization, and the following results may be obtained:

[0057] Result 1: When there is liquid seepage at the device interface or in the sensor sealed cabin, it indicates that there is a water leakage problem at the device interface of the sensor performance testing device or in the sensor sealed cabin; when the air compressor cannot pressurize to the specified pressure, it indicates that there is an air leakage problem in the sensor performance testing device.

[0058] Result 2: There is no water leakage or air leakage at the device interface, and when the water pressure monitoring data of the sensor and the data of the air compressor change synchronously over time, if the two data are equal, it indicates that the sealing performance, sensitivity, accuracy, and long-term working stability of the entire sensor testing device are good, and it is not blocked; if the two data are not equal, it indicates that the sealing performance and sensitivity of the testing device are good, but the accuracy is lacking, and there may be a blockage problem.

[0059] Result 3: There is no water leakage or air leakage at the device interface, and the water pressure monitoring data of the sensor and the data of the air compressor do not change synchronously over time. If the two data are equal, it indicates that the sealing performance of the entire sensor testing device is good, the accuracy is accurate, but the sensitivity is lacking, or there may be a problem of slow water pressure transmission; if the two data are not equal, it indicates that the sealing performance and sensitivity of the testing device are good, but the accuracy is lacking, and there may be a blockage problem.

[0060] Result 4: There is no water leakage or air leakage at the device interface, and when the sensor cannot measure the water pressure monitoring data, it indicates that there is a problem with the sensor.

[0061] For the problems that appear in the above results, the following measures are specifically proposed to solve or improve:

[0062] Measure 1: For the problem of water leakage and air leakage of the testing device in Result 2, the testing device should be rechecked and improved.

[0063] Measure 2: For the problem of unequal data in Results 2, 3, and 4, the outer shell of the sensor sealed cabin should be replaced. If this problem still exists, the sensor needs to be replaced.

[0064] Measure 3: For the problem of asynchronous data in Result 3, considering that the sensor sealing device is blocked, the filter screen of the sensor sealed cabin should be adjusted or the geotextile should be replaced.

[0065] Measure 4: For the problem of no data of the sensor in Result 4, it should be checked whether the water pressure sensor is in a normal working state.

[0066] This embodiment can truly simulate the process of monitoring the water pressure sensor on the shield body during the tunneling state of the shield machine, and can accurately measure the change law, friction, and blockage situation of the pore water pressure monitored by the water pressure sensor on the shield body during the tunneling state of the shield machine. This embodiment has low cost and good effect, and has a broad application prospect. The matters not covered by the present invention are well-known technologies.

Claims

1. A water pressure sensor performance test device simulating the tunneling state of a shield machine, including a mounting base; characterized in that: Also includes: A rotating mechanism is disposed in the mounting base; The outer cylinder is arranged on the mounting base; the interior of the outer cylinder is a hollow structure, and an air compressor interface is provided on the side thereof; A shield shell is located in the hollow structure and is transmission-connected to the rotating mechanism; a predetermined distance is left between the shield shell and the outer cylinder to form a filling chamber; A sensor sealed cabin is detachably mounted in the shield shell; a water pressure sensor is arranged in the sensor sealed cabin; A slip ring is arranged on the top of the shield shell and located at the rotation center; the slip ring is used to simulate the excavation state of the water pressure sensor along with the shield body in the stratum; The sensor sealed cabin comprises: The shell has a hollow structure inside; both ends of the shell are open structures, namely a connecting end and a hatch end; A sandwich sealing plate is radially fixed to the connecting end; the sandwich sealing plate is configured to fix the water pressure sensor; the power line and data line of the water pressure sensor are led out through the hatch end, and the connecting end is connected to the shield shell body by threads; the sandwich sealing plate comprises: two layers of organic glass plates and a geotextile arranged between the two layers of organic glass plates; wherein the organic glass plates are perforated.

2. The water pressure sensor performance testing device under the simulated shield machine excavation state according to claim 1 is characterized in that: The rotating mechanism comprises: A stepper motor is installed in the mounting base; A coupling is transmission-connected to the output shaft of the stepper motor; the coupling is transmission-connected to the shield shell.

3. The water pressure sensor performance testing device under the simulated shield machine excavation state according to claim 1 is characterized in that: The slip ring comprises: A rotor connected to the shield shell; The stator moves axially through the rotor; the stator is fixedly connected to the rotor, and a predetermined gap is left between the stator and the rotor to form an annular cavity, and the annular cavity is configured to lead out power lines and data lines.

4. A method for testing the performance of a water pressure sensor under a simulated shield machine excavation state, using a water pressure sensor performance testing device under a simulated shield machine excavation state as claimed in any one of claims 1 to 3, characterized in that: The following steps are all tested during the rotation process: Step 1: Connect the test device to the air compressor through the air compressor interface, and the air compressor is connected to the outer cylinder, on which a water pressure monitoring device is installed; after the installation is completed, first check the air tightness of the interface and the airtightness of the sensor sealed cabin: observe whether there is liquid seepage at the interface to determine whether the interface and the sensor sealed cabin are leaking, and observe whether the water pressure monitoring data measured by the water pressure monitoring device is consistent with the air compressor data to determine whether the sensor performance test device is leaking; Step 2: The outer cylinder is filled with pure water, the water pressure sensor is installed in the sensor sealed cabin, the air compressor is connected to the outer cylinder, the initial pressure value in the air compressor is set, and the pressure is gradually increased to the pressure threshold P according to the gradient of the pressure difference ΔP; each time the pressure difference ΔP is increased, the response time of the water pressure sensor is synchronously obtained , n is the number of times the pressure difference ΔP increases; when the pressure in the air compressor reaches the pressure threshold, the water pressure monitoring data under pure water conditions is obtained, and the reading of the water pressure sensor is recorded as P1; Step 3: Inject mud into the outer cylinder, set the initial pressure value in the air compressor, and gradually increase the pressure to the pressure threshold value P according to the gradient of the pressure difference ΔP; each time the pressure difference ΔP is increased, the response time of the water pressure sensor is synchronously obtained. , n is the number of times the pressure difference ΔP increases; when the pressure in the air compressor reaches the pressure threshold, the water pressure monitoring data under the mud working condition is obtained, and the reading of the water pressure sensor is recorded as P2; the water pressure sensor readings P1 and P2 under the same pressure are compared and analyzed to determine whether the water pressure sensor is blocked; the stabilization time of the water pressure sensor after the air compressor is pressurized to the specified pressure is compared to determine the sensitivity performance of the water pressure sensing device; Step 4: Use the air compressor to pressurize at will and get the pressurization value , simulate the different water pressure conditions that may occur during shield tunneling and excavation, and obtain the current reading P3 of the water pressure sensor.

5. The method for testing the performance of a water pressure sensor under a simulated shield machine excavation state according to claim 4 is characterized in that: Also includes: When liquid seeps out from the device interface or the sensor sealed cabin, it indicates that there is water leakage at the sensor performance test device interface or the sensor sealed cabin; When the air compressor cannot pressurize to the specified pressure, it means that the sensor performance test device has a leak; There is no water or air leakage at the interface of the device, and when the water pressure monitoring data of the sensor and the air compressor data change synchronously over time, if the two data are equal, it means that the sealing performance and sensitivity of the entire sensor test device are good, the accuracy is accurate, and it is not blocked; if the two data are not equal, the sealing performance and sensitivity of the test device are good, the accuracy is insufficient, and there is a blockage problem; There is no water leakage or air leakage at the interface of the device, and the sensor water pressure monitoring data and the air compressor data do not change synchronously with time. If the two data are equal, it means that the entire sensor test device has good sealing performance and accurate accuracy, but lacks sensitivity and there is a blockage problem; if the two data are not equal, it means that the test device has good sealing performance and sensitivity, but lacks accuracy and there is a blockage problem; there is no water leakage or air leakage at the interface of the device, and when the sensor cannot measure the water pressure monitoring data, it means that there is a problem with the sensor.

6. The method for testing the performance of a water pressure sensor under a simulated shield machine excavation state according to claim 4 is characterized in that: Improvement measures include: increasing the sealing of the device interface, replacing the sensor, replacing the geotextile or checking the working status of the water pressure sensor.

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