Model experiment device for measuring floating of shield lining segment and working method of model experiment device

Abstract

The invention relates to a model experiment device for measuring floating of a shield lining segment and a working method thereof, and the device comprises a test cylinder which is internally provided with a to-be-tested segment; the air compression unit is used for applying pressure to the test cylinder; the duct piece buoyancy testing unit is used for testing the buoyancy of the duct piece to be tested in the slurry layer; the drainage unit is used for collecting water in the water collecting layer; and the data collecting and processing unit is used for collecting the electric signal of the segment buoyancy testing unit to obtain the buoyancy of the to-be-tested segment. The invention discloses a model experiment device for measuring floating of a shield lining segment, relates to the technical field of shield construction, and monitors the change of buoyancy on the lining segment through a drainage collecting device, a gravity sensor and the like. The buoyancy on the lining segment in the construction period can be measured with higher precision, the capability of continuously collecting the change rule of the buoyancy on the lining segment in the slurry solidification process is achieved, and then the appropriate synchronous grouting anti-floating slurry ratio under different stratums and grouting pressures is selected.

Description

Technical Field

[0001] The invention relates to the technical field of shield construction, in particular to an experimental device for measuring the floating model of a shield lining segment and a working method thereof. Background Art

[0002] In recent years, shield construction has been widely used in urban rail transit construction due to its high speed, high safety and high degree of mechanization. Considering the completeness of urban traffic tunnel service facilities, the diameter of tunnel excavation section has gradually developed from medium and small diameters to large and even super-large diameters.

[0003] With the increase of shield excavation section and shield tunnel diameter, problems such as segment misalignment, partial segment damage and segment water leakage caused by segment floating during shield construction period are becoming more and more obvious. Usually, after the shield segments are assembled into a ring and separated from the shield tail during the construction period, there is a certain size of annular gap between the outer wall of the segment and the surrounding rock and soil, which provides space for the segment to shift or float. Then, slurry is injected into the space between the surrounding rock and soil and the outer wall of the segment for filling. Since the initial setting of the slurry takes a certain amount of time, the segment will be surrounded by the flowing slurry during this period. If the buoyancy generated by the flowing slurry is greater than the gravity of the segment itself, the segment may float. When the segments in the tunnel float, it will cause segment misalignment, extrusion damage and even sand and water gushing.

[0004] Although my country has accumulated a lot of technical experience in shield tunnel construction, the construction of large-diameter shield tunnels is still in its initial development stage. There are still some deficiencies in the theoretical research and control measures on the buoyancy of the segments. There is still a lack of effective test devices for measuring the buoyancy of the lining segments during the construction period. In order to achieve safe and efficient construction of large-diameter shield tunnels, it is very necessary to conduct research on the buoyancy of the segments during the construction process and propose a reasonable and effective experimental device for measuring the buoyancy of the shield lining segments. Summary of the invention

[0005] To this end, the technical problem to be solved by the present invention is that although a lot of research has been carried out on buoyancy, it has been applied to actual projects and has achieved rich results, but the buoyancy of the lining segments during the shield construction period is converted through theoretical calculations. The existing calculations do not strictly consider the time-varying nature of the slurry and the lack of the law of dissipation of buoyancy, and the only model test device has deficiencies such as insufficient measurement accuracy and discontinuous buoyancy data collection, resulting in the lack of effective slurry buoyancy test devices, resulting in no consensus on the law of buoyancy change, and the mechanism of slurry buoyancy change needs to be clarified. However, in actual projects, buoyancy has an important influence on the size of the buoyancy and construction safety. However, there are currently few studies on the law of buoyancy change of segment linings under different slurry mix ratios and admixtures, which makes the relevant research on the anti-floating slurry mix ratio lack reference and basis, and the law of the influence of slurry properties on static buoyancy still needs to be studied. Therefore, in order to truly restore the buoyancy of the segment lining under actual grouting construction conditions, selecting appropriate synchronous grouting anti-floating slurry ratios under different strata and grouting pressures is the core problem to be solved by the present invention.

[0006] In order to solve the above technical problems, the present invention provides a shield lining segment buoyancy model test device, comprising: a test cylinder, an air pressure unit, a segment buoyancy test unit, a drainage unit and a data collection and processing unit; the test cylinder is vertically arranged, and the test cylinder is sequentially divided into a slurry layer, a soil layer and a water collection layer from top to bottom, the slurry layer is used to place the segment to be tested, the segment to be tested is a proportional reduction of the actual model segment of the project, and the segment to be tested is used to directly simulate the lining segment in the project, and the water collection layer is used to collect the slurry layer under pressurized conditions. The invention relates to a method for collecting water after consolidation and penetration of the soil layer; an air compression unit, which is connected to the test cylinder and is used to apply pressure to the test cylinder; a segment buoyancy test unit, which is used to connect the segment to be tested and the test cylinder, and the segment buoyancy test unit is used to test the buoyancy of the segment to be tested in the slurry layer; a drainage unit, which is connected to the test cylinder and is used to collect water in the water collection layer; a data collection and processing unit, which is electrically connected to the segment buoyancy test unit, and the data collection and processing unit is used to collect the electrical signal of the segment buoyancy test unit to obtain the buoyancy of the segment to be tested. The shield lining segment buoyancy model experimental device of the present invention can achieve higher-precision measurement of the buoyancy of the lining segment during the construction period by setting different grouting pressures, different soil types and different proportions of synchronous grouting slurries, and monitoring the changes in the buoyancy of the segment lining segments through drainage collection devices, gravity sensors, etc., and has the ability to continuously collect the change law of the buoyancy of the lining segment during the slurry solidification process, and then select the appropriate synchronous grouting anti-buoyancy slurry ratio under different formations and grouting pressures.

[0007] In one embodiment of the present invention, the test cylinder includes an upper flange, a lower bottom plate, an upper cylinder, a lower cylinder and an intermediate flange, the lower end of the upper cylinder and the upper end of the lower cylinder are connected as a whole through the intermediate flange, and the upper cylinder and the lower cylinder are connected, the pipe segment to be tested is arranged in the upper cylinder, the upper flange cover is arranged on the upper end of the upper cylinder, the lower bottom plate is arranged on the lower end of the lower cylinder, the slurry layer is arranged in the upper cylinder, the soil layer and the water collection layer are arranged in the lower cylinder, the air compression unit is connected to the upper flange, and the air compression unit is connected to the internal cavity of the upper cylinder, and the drainage unit is connected to the lower cylinder.

[0008] In one embodiment of the present invention, two symmetrically arranged guide grooves are provided on the inner wall of the upper cylinder, and the two symmetrically arranged guide grooves are located at two ends of the same diameter of the upper cylinder. The two ends of the pipe segment to be tested are arranged in the guide grooves, and the guide grooves are used to limit the horizontal movement of the pipe segment, so that the pipe segment to be tested is only subjected to the longitudinal buoyancy, and will not cause deviation in buoyancy measurement due to lateral horizontal movement.

[0009] In one embodiment of the present invention, the air compression unit includes an air compressor and a PU air duct, and the output end of the air compressor is connected through the PU air duct and a threaded joint on the upper flange.

[0010] In one embodiment of the present invention, the segment buoyancy test unit includes a gravity sensor and a force transmission rod, the upper and lower ends of the gravity sensor are a fixed end and a force transmission end respectively, the fixed end of the gravity sensor is fixedly connected to an upper flange, the force transmission end of the gravity sensor is connected to the force transmission rod, the force transmission rod is connected to the segment to be tested, the gravity sensor is electrically connected to a data collection and processing unit via a data line, and the data collection and processing unit is used to collect electrical signals from the gravity sensor.

[0011] In one embodiment of the present invention, a pressurizing hole is provided on the upper flange plate, and the air compressor is connected to the pressurizing hole through a PU air duct. The air compressor pressurizes the inside of the test cylinder, and the air compressor acts on the slurry layer by pressurizing the inside of the test cylinder to simulate the grouting pressure of the synchronous grouting slurry in actual engineering.

[0012] In one embodiment of the present invention, the drainage unit includes a hose and a water collecting cup, one end of the hose is connected to the lower cylinder, and the other end of the hose is connected to the water collecting cup.

[0013] In one embodiment of the present invention, the data collection and processing unit includes a computer and a data acquisition instrument, one end of the data acquisition instrument is connected to the gravity sensor via a data cable, and the other end of the data acquisition instrument is connected to the computer, and the data acquisition instrument is used to collect electrical signals from the gravity sensor.

[0014] The present invention provides a working method of a shield lining segment floating model experimental device, comprising the following steps: S1. Install the test device before the test. After fixing, close the air pump valve on the air compressor, open the pressure valve to perform a sealing test, and check whether there is any leakage in the test tube. S2. Pour the weighed test soil sample evenly into the test tube, so that the test soil fills the soil layer at the bottom of the test tube; S3. Apply a thin layer of vaseline on the inner wall of the guide groove and fix the pipe segment to be tested in the guide groove; S4. Install the gravity sensor, fix the fixed end of the gravity sensor on the flange on the top of the test tube, and connect the force transmission end of the gravity sensor to the force transmission rod. At the same time, the gravity sensor for each test should be adjusted to the same height. The gravity sensor is connected to the computer through the data acquisition instrument; S5. Both sides of the bottom of the force transmission rod are connected to the pipe segment to be tested by screws; S6. Prepare the test slurry according to the construction slurry mix ratio, stir the slurry fully to prevent gelled sediment and sand from adhering to the bottom of the test tube. To ensure that the segments to be tested in each group of tests have the same test boundary conditions, pour the test slurry slowly into the test tube until the slurry liquid level reaches 20 cm after stirring evenly. At the same time, the bottom of the force transmission rod is immersed 2 cm below the liquid surface, so that the slurry evenly wraps the segments to be tested. S7. Turn on the air compressor and adjust the pressure gauge to the set position to simulate the pressure on the slurry; S8. Set the data acquisition instrument to automatic monitoring, click Start on the sensor acquisition interface of the data acquisition instrument, and use the sensor to collect the vertical combined force on the segment to be tested during the slurry solidification process, that is, the change law of the longitudinal combined force on the gravity sensor. Use the acquisition device to record the data of the change of the longitudinal combined force on the gravity sensor during the test, and further analyze and demonstrate to obtain the floating law of the segment to be tested in the whole process; S9. After completing the buoyancy test of one slurry, take out the test column from the pipe segment to be tested and clean it, replace the slurry with different proportions and repeat steps S1 to S8. After data processing, the changing law of the influence of slurries with different proportions on the buoyancy of the pipe segment to be tested during the slurry solidification process is obtained.

[0015] Compared with the prior art, the shield lining segment floating model test device and the working method thereof described in the present invention have the following beneficial effects: 1. Through the setting of gravity sensor and data acquisition device, the device has higher accuracy and the ability to continuously collect the changing law of segment lining buoyancy during the test process, that is, the slurry solidification process.

[0016] 2. The use of air compressor pressurization and pressure regulating valve can simulate the confining pressure conditions of the slurry during the actual construction process, which better ensures the reliability of the model test and realizes the measurement of the changing law of the buoyancy of the synchronous grouting slurry under different confining pressures.

[0017] 3. By setting a soil layer at the bottom of the device, the actual soil layer can be simulated. At the same time, a drainage valve is set to further simulate the slurry consolidation and drainage in the actual project, and to achieve the measurement of the changing law of the buoyancy of the synchronous grouting slurry under different strata.

[0018] 4. By setting a flange on the upper part of the experimental device, multiple experiments can be carried out. Slurries of different proportions can be added into the experimental container through the flange port to measure the buoyancy of different types of slurries and slurries of different proportions. The slurry proportion scheme can be further optimized through subsequent indoor experimental measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein Figure 1 It is a front view of a model experimental device for measuring the floating of a shield lining segment and a working method thereof in a preferred embodiment of the present invention; Figure 2 A top view of a model experimental device for measuring the floating of a shield lining segment and a working method thereof in a preferred embodiment of the present invention; Figure 3 This is a diagram of a segment buoyancy testing device in a preferred embodiment of the present invention.

[0020] Explanation of the reference numerals in the specification: test cylinder 100, slurry layer 101, soil layer 102, water collecting layer 103, upper flange 11, pressurized hole 111, lower base plate 12, upper cylinder 13, guide groove 131, lower cylinder 14, middle flange 15, partition plate 16, air compression unit 200, air compressor 21, PU air duct 22, pressure valve 23, segment buoyancy test unit 300, gravity sensor 31, force transmission rod 32, drainage unit 400, hose 41, water collecting cup 42, data collection and processing unit 500, computer 51, data acquisition instrument 52, segment to be tested 600. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0022] Reference Figure 1-3As shown, the shield lining segment buoyancy model test device of the present invention comprises: a test cylinder 100, an air pressure unit 200, a segment buoyancy test unit 300, a drainage unit 400 and a data collection and processing unit 500; the test cylinder 100 is vertically arranged, and the test cylinder 100 is sequentially divided into a slurry layer 101, a soil layer 102 and a water collection layer 103 from top to bottom, the slurry layer 101 is used to place the segment 600 to be tested, and the water collection layer 103 is used to collect the moisture after the slurry layer 101 is consolidated under pressure and penetrates the soil layer 102; the air pressure unit 200 is connected to the test cylinder 100, and The air pressure unit 200 is used to apply pressure to the test cylinder 100; the segment buoyancy test unit 300 is used to connect the segment 600 to be tested and the test cylinder 100, and the segment buoyancy test unit 300 is used to test the buoyancy of the segment 600 to be tested in the slurry layer 101; the drainage unit 400 is connected to the test cylinder 100, and the drainage unit 400 is used to collect moisture in the water collection layer 103; the data collection and processing unit 500 is electrically connected to the segment buoyancy test unit 300, and the data collection and processing unit 500 is used to collect the electrical signal of the segment buoyancy test unit 300 to obtain the buoyancy of the segment 600 to be tested. The segment 600 to be tested is a proportional reduction of the actual model segment of the project, and the segment 600 to be tested is used to directly simulate the lining segment in the project.

[0023] In the above structure, the test cylinder 100 includes an upper flange 11, a lower bottom plate 12, an upper cylinder 13, a lower cylinder 14 and an intermediate flange 15. The lower end of the upper cylinder 13 and the upper end of the lower cylinder 14 are connected as a whole through the intermediate flange 15, and the upper cylinder 13 and the lower cylinder 14 are connected. The pipe segment 600 to be tested is arranged in the upper cylinder 13, the upper flange 11 is covered on the upper end of the upper cylinder 13, the lower bottom plate 12 is arranged on the lower end of the lower cylinder 14, the slurry layer 101 is arranged in the upper cylinder 13, the soil layer 102 and the water collection layer 103 are arranged in the lower cylinder 14, the air compression unit 200 is connected to the upper flange 11, and the air compression unit 200 is connected to the internal cavity of the upper cylinder 13, and the drainage unit 400 is connected to the lower cylinder 14. The upper cylinder 13 and the lower cylinder 14 are both cylinders with openings at both ends. Partition plates 16 are provided between the slurry layer 101 and the soil layer 102, and between the soil layer 102 and the water collecting layer 103. The partition plates 16 are circular plates with holes. The slurry layer 101 consolidates and loses water when pressurized by the air compression unit 200. Water flows into the soil layer 102 through the partition plate 16 between the slurry layer 101 and the soil layer 102 for infiltration. The water infiltrated from the soil layer 102 is gathered in the water collecting layer 103 through the partition plate 16 between the soil layer 102 and the water collecting layer 103. The slurry layer 101 will not completely fill the upper cylinder 13, so that a cavity is left between the upper end of the upper cylinder 13 and the upper flange 11, and the air compression unit 200 is connected to the cavity between the upper end of the upper cylinder 13 and the upper flange 11, so that the air compression unit 200 can inflate the cavity between the upper end of the upper cylinder 13 and the upper flange 11, and apply pressure to the slurry layer 101. The upper cylinder 13 is used to place experimental slurry and pipe segments; the lower cylinder 14 is used to place experimental soil layers to simulate actual soil layers. When the test cylinder 100 is pressurized, the pressure acts on the grouting slurry to consolidate and drain it, and the buoyancy dissipation law of the slurry under different formation conditions can be measured indoors.

[0024] In the above structure, two symmetrically arranged guide grooves 131 are provided on the inner wall of the upper cylinder 13, and the two symmetrically arranged guide grooves 131 are located at the two ends of the same diameter of the upper cylinder 13. The two ends of the pipe segment 600 to be tested are arranged in the guide grooves 131, and the guide grooves 131 are used to limit the horizontal movement of the pipe segment 600, so that the pipe segment 600 to be tested is only subjected to the buoyancy in the longitudinal direction of the test, and will not cause the buoyancy measurement to be deviated due to the lateral horizontal movement. The guide grooves 131 prevent the pipe segment 600 to be tested from moving forward and backward, that is, limit the pipe segment 600 to be tested to be in a fixed position of the upper cylinder 13, so that the pipe segment 600 to be tested is only subjected to the buoyancy in the longitudinal direction of the test, and will not cause the buoyancy measurement to be deviated due to the lateral horizontal movement. The guide grooves 131 are set so that the pipe segment 600 to be tested is always in a stable state during the test process, ensuring the stability of data acquisition.

[0025] In the above structure, the air compression unit 200 includes an air compressor 21, a PU air duct 22 and a pressure valve 23. The output end of the air compressor 21 is connected to the threaded joint on the upper flange 11 through the PU air duct 22. The PU air duct 22 is arranged at one end of the upper flange 11 and communicates with the inner wall of the upper cylinder 13. The pressure valve 23 is arranged on the PU air duct 22 for detecting the gas pressure. The upper flange 11 is provided with a pressurizing hole 111. The air compressor 21 is connected to the pressurizing hole 111 through the PU air duct 22. The air compressor 21 pressurizes the inside of the test cylinder 100, and the air compressor 21 pressurizes the inside of the test cylinder 100 on the slurry layer 101 to simulate the grouting pressure of the synchronous grouting slurry in the actual engineering. The air compressor 21 can adjust the pressurization size, and then can simulate the pressure size of the actual synchronous grouting slurry, and realize the measurement of the slurry buoyancy dissipation law under different pressure difference conditions indoors.

[0026] In the above structure, the segment buoyancy test unit 300 includes a gravity sensor 31 and a force transmission rod 32. The upper and lower ends of the gravity sensor 31 are a fixed end and a force transmission end respectively. The fixed end of the gravity sensor 31 is fixedly connected to the upper flange 11. The force transmission end of the gravity sensor 31 is connected to the force transmission rod 32. The force transmission rod 32 is connected to the segment 600 to be tested. The gravity sensor 31 is electrically connected to the data collection and processing unit 500 through a data line, and the data collection and processing unit 500 is used to collect the electrical signal of the gravity sensor 31. During the test, the segment 600 to be tested will lean against the two sides of the force transmission rod 32 under the action of buoyancy, so that the buoyancy change data of the segment 600 to be tested during the slurry solidification process can be continuously collected.

[0027] In the above structure, the drainage unit 400 includes a hose 41 and a water collecting cup 42 . One end of the hose 41 is connected to the lower cylinder 14 , and the other end of the hose 41 is connected to the water collecting cup 42 .

[0028] In the above structure, the data collection and processing unit 500 includes a computer 51 and a data acquisition instrument 52. One end of the data acquisition instrument 52 is connected to the gravity sensor 31 through a data line, and the other end of the data acquisition instrument 52 is connected to the computer 51. The data acquisition instrument 52 is used to collect the electrical signal of the gravity sensor 31. One end of the data acquisition instrument 52 is connected to the gravity sensor 31 through a data line. During the experiment, the elastic element inside the gravity sensor 31 produces elastic deformation under the action of external force, so that the resistance strain gauge attached to the surface of the element is also deformed, so that its resistance value changes, and then the resistance change is converted into an electrical signal through the corresponding measurement circuit, thereby completing the process of converting the external force into the electrical signal. The other end of the data acquisition instrument 52 is connected to the computer 51. By collecting the electrical signal tested by the gravity sensor 31, the buoyancy change of the pipe segment 600 to be tested can be continuously collected.

[0029] Based on the above structure, a working method of a shield lining segment floating model experimental device is provided, comprising the following steps: S1. Install the test device before the test. After the fixation is completed, close the air pump valve on the air compressor 21, open the pressure valve 23 to perform a sealing test, and check whether the test cylinder 100 has air leakage; S2. Pour the weighed test soil sample evenly into the test tube 100, so that the test soil fills the soil layer 102 at the lower part of the test tube 100; S3, applying a thin layer of vaseline on the inner wall of the guide groove 131, and fixing the pipe segment 600 to be tested in the guide groove 131; S4, install the gravity sensor 31, fix the fixed end of the gravity sensor 31 on the flange 11 on the top of the test tube 100, and connect the force transmission end of the gravity sensor 31 to the force transmission rod 32. At the same time, the gravity sensor 31 of each test should be adjusted to the same height. The gravity sensor 31 is connected to the computer 51 through the data acquisition instrument 52; S5. Both sides of the bottom of the force transmission rod 32 are connected to the pipe segment 600 to be tested by screws; S6. Prepare the test slurry according to the construction slurry mix ratio, stir the slurry fully to prevent the gelled sediment and sand from adhering to the bottom of the test tube 100. To ensure that the tested segments 600 of each group of tests have the same test boundary conditions, after stirring evenly, slowly pour the test slurry into the test tube 100 until the slurry liquid level reaches 20 cm, and at the same time, the bottom of the force transmission rod 32 is immersed 2 cm below the liquid surface, so that the slurry evenly wraps the tested segment 600; S7, turn on the air compressor 21, adjust the pressure gauge to a set position, and simulate the pressure on the slurry; S8, setting the data acquisition instrument 52 to automatic monitoring, clicking "Start" on the sensor acquisition interface of the data acquisition instrument 52, collecting the vertical resultant force on the tested segment 600 during the slurry solidification process, that is, the change law of the longitudinal resultant force on the gravity sensor 31, through the sensor, recording the data of the change of the longitudinal resultant force on the gravity sensor 31 during the test through the acquisition device, further analyzing and demonstrating to obtain the floating law of the tested segment 600 in the whole process; S9. After completing the buoyancy test of one slurry, take out the test column of the pipe segment 600 to be tested and clean it, replace the slurry with different proportions and repeat steps S1 to S8. After data processing, the changing law of the influence of slurries with different proportions on the buoyancy of the pipe segment 600 to be tested during the slurry solidification process is obtained.

[0030] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A model experimental device for measuring the floating of shield lining segments, characterized in that: include: Test cylinder, air compression unit, segment buoyancy test unit, drainage unit and data collection and processing unit; The test cylinder is vertically arranged and is divided into a slurry layer, a soil layer and a water collection layer from top to bottom. The slurry layer is used to place the pipe segment to be tested. The pipe segment to be tested is a proportional reduction of the actual model pipe segment of the project, and the pipe segment to be tested is used to directly simulate the lining pipe segment in the project. The water collection layer is used to collect moisture after the slurry layer is consolidated under pressure and penetrates the soil layer; An air pressure unit is connected to the test cylinder and is used to apply pressure to the test cylinder; A segment buoyancy test unit, which is used to connect the segment to be tested and the test tube, and the segment buoyancy test unit is used to test the buoyancy of the segment to be tested in the slurry layer; A drainage unit is communicated with the test cylinder and is used to collect water in the water collection layer; The data collection and processing unit is electrically connected to the segment buoyancy testing unit, and is used to collect the electrical signal of the segment buoyancy testing unit to obtain the buoyancy of the segment to be tested.

2. The shield lining segment floating model test device according to claim 1 is characterized by: The test cylinder comprises an upper flange, a lower bottom plate, an upper cylinder, a lower cylinder and an intermediate flange. The lower end of the upper cylinder and the upper end of the lower cylinder are connected as a whole through the intermediate flange, and the upper cylinder is communicated with the lower cylinder. The pipe segment to be tested is arranged in the upper cylinder, the upper flange cover is arranged on the upper end of the upper cylinder, the lower bottom plate is arranged on the lower end of the lower cylinder, the slurry layer is arranged in the upper cylinder, the soil layer and the water collection layer are arranged in the lower cylinder, the air compression unit is connected to the upper flange, and the air compression unit is communicated with the internal cavity of the upper cylinder, and the drainage unit is communicated with the lower cylinder.

3. The shield lining segment floating model test device according to claim 2 is characterized by: Two symmetrically arranged guide grooves are provided on the inner wall of the upper cylinder, and the two symmetrically arranged guide grooves are located at the two ends of the same diameter of the upper cylinder. The two ends of the pipe segment to be tested are arranged in the guide grooves, and the guide grooves are used to limit the horizontal movement of the pipe segment, so that the pipe segment to be tested is only subjected to the longitudinal buoyancy, and will not cause deviation in buoyancy measurement due to lateral horizontal movement.

4. The shield lining segment floating model test device according to claim 2 is characterized by: The air compression unit comprises an air compressor and a PU air duct, and the output end of the air compressor is connected via a threaded joint on the PU air duct and the upper flange.

5. The shield lining segment floating model test device according to claim 4 is characterized by: The segment buoyancy test unit includes a gravity sensor and a force transmission rod. The upper and lower ends of the gravity sensor are a fixed end and a force transmission end respectively. The fixed end of the gravity sensor is fixedly connected to an upper flange. The force transmission end of the gravity sensor is connected to the force transmission rod. The force transmission rod is connected to the segment to be tested. The gravity sensor is electrically connected to a data collection and processing unit via a data line, and the data collection and processing unit is used to collect electrical signals from the gravity sensor.

6. The shield lining segment floating model test device according to claim 5 is characterized by: A pressurizing hole is provided on the upper flange, and the air compressor is connected to the pressurizing hole through a PU air duct. The air compressor pressurizes the inside of the test cylinder, and the air compressor acts on the slurry layer by pressurizing the inside of the test cylinder to simulate the grouting pressure of the synchronous grouting slurry in actual engineering.

7. The shield lining segment floating model test device according to claim 5 is characterized by: The drainage unit comprises a hose and a water collecting cup, one end of the hose is connected to the lower cylinder, and the other end of the hose is connected to the water collecting cup.

8. The shield lining segment floating model test device according to claim 5 is characterized by: The data collection and processing unit includes a computer and a data acquisition instrument. One end of the data acquisition instrument is connected to the gravity sensor through a data line, and the other end of the data acquisition instrument is connected to the computer. The data acquisition instrument is used to collect the electrical signal of the gravity sensor.

9. The working method of the shield lining segment floating model test device according to claim 8 is characterized by: The steps include: S1. Install the test device before the test. After fixing, close the air pump valve on the air compressor, open the pressure valve to perform a sealing test, and check whether there is any leakage in the test tube. S2. Pour the weighed test soil sample evenly into the test tube, so that the test soil fills the soil layer at the bottom of the test tube; S3. Apply a thin layer of vaseline on the inner wall of the guide groove and fix the pipe segment to be tested in the guide groove; S4. Install the gravity sensor, fix the fixed end of the gravity sensor on the flange on the top of the test tube, and connect the force transmission end of the gravity sensor to the force transmission rod. At the same time, the gravity sensor for each test should be adjusted to the same height. The gravity sensor is connected to the computer through the data acquisition instrument; S5. Both sides of the bottom of the force transmission rod are connected to the pipe segment to be tested by screws; S6. Prepare the test slurry according to the construction slurry mix ratio, stir the slurry fully to prevent gelled sediment and sand from adhering to the bottom of the test tube. To ensure that the segments to be tested in each group of tests have the same test boundary conditions, pour the test slurry slowly into the test tube until the slurry liquid level reaches 20 cm after stirring evenly. At the same time, the bottom of the force transmission rod is immersed 2 cm below the liquid surface, so that the slurry evenly wraps the segments to be tested. S7. Turn on the air compressor and adjust the pressure gauge to the set position to simulate the pressure on the slurry; S8. Set the data acquisition instrument to automatic monitoring, click Start on the sensor acquisition interface of the data acquisition instrument, and use the sensor to collect the vertical combined force on the segment to be tested during the slurry solidification process, that is, the change law of the longitudinal combined force on the gravity sensor. Use the acquisition device to record the data of the change of the longitudinal combined force on the gravity sensor during the test, and further analyze and demonstrate to obtain the floating law of the segment to be tested in the whole process; S9. After completing the buoyancy test of one slurry, take out the test column from the pipe segment to be tested and clean it, replace the slurry with different proportions and repeat steps S1 to S8. After data processing, the changing law of the influence of slurries with different proportions on the buoyancy of the pipe segment to be tested during the slurry solidification process is obtained.

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