A test device for segment deformation caused by local liquefaction of sand and soil and its use method

Abstract

The present invention provides a test device for detecting segment deformation caused by local liquefaction of sand and soil, and a method for using the test device. The test device includes a reaction frame, multiple stratum load simulation devices, multiple segment structures, a crossbeam, multiple displacement gauges, an earth pressure gauge, a box, and ice cream. The reaction frame is installed on the periphery of the box, and multiple stratum load simulation devices are installed inside the reaction frame, and the stratum load simulation devices are connected to the box. The multiple segment structures are sequentially installed together to form a segment ring, which is installed in the box, and the front and rear ends of the segment ring are respectively connected to the box. The crossbeam is installed in the segment ring, and the displacement gauge is installed between the crossbeam and the inner wall of the segment ring. The space between the outer wall of the segment ring and the inner wall of the box is used for laying sand and soil. Ice cream is buried at a predetermined position in the sand and an earth pressure gauge is buried in the sand, and the earth pressure gauge is buried in the sand, and the earth pressure gauge is buried at a position corresponding to the stratum load simulation device. The beneficial effect of the present invention is that the present invention realizes local liquefaction of sand and soil, simulating actual engineering.

Description

Technical Field

[0001] The present invention relates to the field of civil engineering, and in particular to a testing device for segment deformation caused by local liquefaction of sand and a use method thereof. Background Art

[0002] Description of prior art:

[0003] In actual engineering, the phenomenon of segmental flotation is an objective reality. Segments that have just been released from the shield tail often experience this phenomenon, manifesting as misalignment, cracking, damage, and even axial misalignment. Analyses of the causes of segment deformation vary. Some are related to the thickness of the overburden above the shield tunnel: the shallower the overburden, the softer the stratum in which the tunnel is located, and the greater the segment deformation. Others are linked to factors such as insufficient simultaneous grouting, uneven grouting pressure, and the presence of voids at the top of the segment. Because the construction environments in which segment deformation occurs vary, the tests that cause segment deformation also vary. Most experiments investigating segment flotation in shield tunnels are conducted indoors, simulating different soil types, overburden depths, and excavation lengths to study the flotation behavior of the tunnel (e.g., CN 104677664 A). However, this approach is not applicable to shield tunnels with greater burial depths, as using an overburden to simulate in-situ earth pressure is impractical. Most devices use grouting around the segments to simulate the floating of the segments and the dynamic changes of the slurry (CN110646164A CN 113295381A CN 212563334U). This device is suitable for the influence of liquid on shield segments, but has a relatively small scope of application and certain limitations.

[0004] Due to the complex on-site construction conditions and uneven stress on the tunnel structure, it is difficult to accurately analyze the tunnel's buoyancy through theoretical analysis. Prototype structure testing is expensive and difficult.

[0005] Therefore, it is urgent to propose an accurate measurement device for the deformation of pipe segments caused by sand liquefaction.

[0006] Problems and defects of existing technology:

[0007] 1. The existing technology uses the method of covering the upper part with soil to simulate the on-site soil pressure, which is impractical for shield tunnels with greater burial depths.

[0008] 2. Some technologies do not consider the effect of soil confining pressure during the experiment, resulting in poor accuracy of the experimental results.

[0009] 3. There is a lack of research on the deformation of shield tunnel segments caused by local liquefaction of sand. Summary of the Invention

[0010] The present invention provides a test device for segment deformation caused by local liquefaction of sand, comprising a reaction frame, multiple formation load simulation devices, multiple segment structures, a crossbeam, multiple displacement meters, an earth pressure gauge, a box body, and ice sand. The reaction frame is installed on the periphery of the box body, multiple formation load simulation devices are installed on the inner side of the reaction frame, and the formation load simulation device is connected to the box body; multiple segment structures are installed together in sequence to form a segment ring, the segment ring is installed in the box body, and the front and rear ends of the segment ring are respectively connected to the box body, the crossbeam is installed in the segment ring, the displacement meter is installed between the crossbeam and the inner wall of the segment ring, the space between the outer wall of the segment ring and the inner wall of the box body is used for paving sand, the ice sand is buried at a predetermined position in the sand, the earth pressure gauge is buried in the sand, and the earth pressure gauge is buried at a position corresponding to the formation load simulation device.

[0011] As a further improvement of the present invention, the stratum load simulation device includes a jack, a distribution beam, and a steel plate. The jack is installed on the distribution beam, the distribution beam is installed on the steel plate, the jack is installed on the inner side of the reaction frame, and the steel plate is installed on the outer side of the box.

[0012] As a further improvement of the present invention, the box body includes a box side cover and a box bottom cover, and a box side cover is installed at the front and rear ends of the box bottom cover. Each of the box side covers is provided with a through hole, and the first pipe segment structure at the front end of the pipe segment ring is installed in the through hole at the front end of the box bottom cover, and the first pipe segment structure at the rear end of the pipe segment ring is installed in the through hole at the rear end of the box bottom cover.

[0013] As a further improvement of the present invention, the number of the ground load simulation devices is nine, one of which is installed on the inner side below the reaction frame and connected to the top of the box, four of which are installed between the reaction frame and the left side of the box, and the remaining four are installed between the reaction frame and the right side of the box.

[0014] As a further improvement of the present invention, one displacement meter is installed between each of the pipe segment structures and the crossbeam; and the reaction frame is a U-shaped reaction frame.

[0015] As a further improvement of the present invention, the test device also includes a fixing device, through which the crossbeam is installed in the pipe ring; the fixing device includes a screw and a nut, and a fixing hole is reserved on the edge of the through hole in the middle of the box side cover. One end of the screw is installed on the crossbeam, and the other end of the screw is installed in the reserved fixing hole and is locked by the nut.

[0016] As a further improvement of the present invention, the test device also includes a strain gauge, and the strain gauge is affixed to the surface of the pipe structure; the test device also includes a protective component, and one of the protective components is installed between the two sides of the top of the box and the reaction frame.

[0017] As a further improvement of the present invention, the test device also includes a sealing gasket, and a sealing gasket is installed between the first tube segment structure at the front end of the tube segment ring and the through hole at the front end of the box bottom cover, and between the first tube segment structure at the rear end of the tube segment ring and the through hole at the rear end of the box bottom cover; the box side cover and the box bottom cover are directly connected by screws or bayonet.

[0018] As a further improvement of the present invention, the test device needs to be carried out in a temperature-controlled box. Before the test is carried out, the test device needs to be assembled and placed in the temperature-controlled box before the experiment.

[0019] The present invention also discloses a method for using a testing device for segment deformation caused by local liquefaction of sand, comprising the following steps:

[0020] Step 1: Assemble the test device. Place the device in a temperature-controlled box before the experiment. Prepare samples below 0°C and then raise the temperature to above 0°C during the experiment.

[0021] Step 2: Align and install the side cover and bottom cover of the box by screws or bayonet, and open through holes in the side cover of the box according to the test size of the tube structure. Keep the sealing of the through hole joints between the tube structure and the side cover of the box throughout the whole process.

[0022] Step 3: Fix the stratum load simulation device and the enclosure components on the reaction frame, and adjust the loading position; the enclosure components on the left and right sides of the box are flush with the outer surfaces of the stratum load simulation devices on the left and right sides of the box, and the lower surface of the stratum load simulation device on the top of the box is flush with the upper surfaces of the enclosure components on the left and right sides of the box.

[0023] Step 4: Lay the first layer of sand and soil. The height of the sand and soil should be flush with the bottom of the through-hole on the side cover of the box. During the laying of the first layer of sand and soil, bury ice sand at the predetermined position and bury the soil pressure gauge in the area corresponding to the stratum load simulation device to observe the magnitude of the applied soil pressure. During the laying process, it is necessary to check whether the device has sand leakage.

[0024] Step 5: Install the first segment structure on the side cover of the box with bolts and sealing gaskets to maintain the sealing of the device. Attach strain gauges on the surface of the segment structure. After completion, splice the next ring of segment structures and strain gauges in sequence. Repeat the above operation until all the segment structures used for the test are spliced. The last ring of segment structure is installed on the side cover of the box with bolts and sealing gaskets.

[0025] Step 6: Reserve bolt holes in the middle of the through holes on the front and rear side panels of the box, connect the beam to the screw rods with bolts, and fix the screw rods to the side covers of the connecting box to ensure that the beam does not move during the test.

[0026] Step 7: Inside the segment, fix one end of the displacement meter to the beam with a bolt and connect the other end to the segment structure. Place displacement meters on all four sides of the beam to measure the displacement of the segment structure in different liquefaction areas from multiple directions.

[0027] Step 8: Lay the second layer of sand and soil, the height of the sand and soil is flush with the top of the segment structure. During the laying of the second layer of sand and soil, bury ice sand at the predetermined position, and bury multiple soil pressure gauges 10 in the space area between the outer wall of the segment ring and the inner wall of the box. The buried position of each soil pressure gauge 10 corresponds to the stratum load simulation device on the left and right sides of the box. Check whether there is sand leakage in the device during the laying process.

[0028] Step 9: Lay the third layer of sand and soil. The height of the sand and soil should be flush with the bottom of the ground load simulation device. During the laying of the third layer of sand and soil, bury ice sand at the predetermined position and bury the soil pressure gauge in the corresponding area on the top of the segment structure. Check whether there is any sand leakage in the device during the laying process.

[0029] Step 10: After the test device is installed, before the test begins, it is necessary to check whether the control circuit of each formation load simulation device is normal.

[0030] Step 11: Control the stratum load simulation device to apply confining pressure to the sand, and stop loading when the value displayed by the soil pressure gauge reaches the calculated value.

[0031] Step 12: After the soil confining pressure stabilizes, adjust the temperature of the temperature control box to melt the ice pre-buried in the sand and achieve partial liquefaction of the sand. During the liquefaction process, observe the changes in the displacement meter and the changes in the segment strain.

[0032] Step 13: After the test is completed, stop loading and recycle the test device as required.

[0033] The beneficial effects of the present invention are: 1. The present invention is carried out in a temperature-controlled box, and the ice cream is pre-buried in a predetermined position inside the sand. By adjusting the temperature, the local liquefaction of the sand is achieved, simulating the actual project; 2. The present invention adopts a jack hydraulic device to apply three-dimensional confining pressure of the soil under actual working conditions to the pipe segment, and more accurately simulates the influence of sand liquefaction on the deformation of the pipe segment under actual working conditions; 3. The present invention buries a pressure gauge inside the sand, which can accurately measure the applied load and improve the accuracy of the test; 4. The present invention arranges strain gauges on the surface of the pipe segment structure to accurately measure the pipe segment strain caused by sand liquefaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is an axial view of the test device of the present invention;

[0035] Figure 2 is a cross-sectional view of the test device of the present invention;

[0036] Figure 3 This is a diagram of the connection structure of the pipe segment structure of the present invention;

[0037] Figure 4 It is a partial structural diagram of the test device of the present invention;

[0038] Figure 5 This is a diagram of the lateral hydraulic loading structure of the formation load simulation device of the present invention;

[0039] Figure 6 This is a diagram of the vertical hydraulic loading structure of the formation load simulation device of the present invention;

[0040] Figure 7 This is a diagram showing the internal structure of the tube segment structure of the present invention;

[0041] Figure 8 1. This is a schematic diagram of the liquefaction of the top of the tube segment of the present invention;

[0042] Figure 9 This is a schematic diagram of the liquefaction of the bottom of the tube segment of the present invention;

[0043] Figure 10 It is a schematic diagram of the liquefaction of the side of the tube segment of the present invention. DETAILED DESCRIPTION

[0044] The present invention discloses a test device for segment deformation caused by local liquefaction of sand. The device is an indoor test device suitable for shield segment deformation caused by liquefaction of sand. A stratum load simulation device is used to apply confining pressure around and on the top of the sand. An earth pressure gauge is buried outside the segment to measure the applied load and simulate the actual earth pressure conditions on site.

[0045] At the same time, the test device of the present invention is carried out in a temperature-controlled box. A certain amount of meltable solids such as ice powder is buried at the place where the sand is intended to liquefy, and the sand is locally liquefied at a fixed point by controlling the temperature change, thereby realizing the phenomenon of sand liquefaction caused by actual engineering.

[0046] Furthermore, the test device of the present invention sets a displacement sensor in the internal space of the pipe segment, which can accurately measure the displacement change when the pipe segment is deformed due to local liquefaction of sand. Strain gauges are set on the surface of the pipe segment, and local liquefaction causes strain on the pipe segment.

[0047] The test device of the present invention simulates actual engineering conditions by adopting a three-dimensional confining pressure loading method to study the deformation of the segment structure 4 caused by local liquefaction of sand.

[0048] like Figure 1-10As shown, the present invention discloses a test device for segment deformation caused by local liquefaction of sand, comprising a reaction frame 2, a plurality of stratum load simulation devices 3, a plurality of segment structures 4, a crossbeam 5, a plurality of displacement meters 9, an earth pressure meter 10, a box, and an ice cream 13. The reaction frame 2 is installed on the periphery of the box, a plurality of stratum load simulation devices 3 are installed on the inner side of the reaction frame 2, and the stratum load simulation devices 3 are connected to the box; a plurality of segment structures 4 are sequentially installed together to form a segment ring, and the segment The ring is installed in the box, and the front and rear ends of the segment ring are respectively connected to the box. The crossbeam 5 is installed in the segment ring, and the displacement meter 9 is installed between the crossbeam 5 and the inner wall of the segment ring. The space between the outer wall of the segment ring and the inner wall of the box is used to lay sand 12. The ice slurry 13 is buried at a predetermined position in the sand 12, and the soil pressure gauge 10 is buried in the sand 12. The soil pressure gauge 10 is buried at a position corresponding to the formation load simulation device 3.

[0049] The stratum load simulation device 3 includes a jack 16, a distribution beam 17, and a steel plate 18. The jack 16 is installed on the distribution beam 17, the distribution beam 17 is installed on the steel plate 18, the jack 16 is installed on the inner side of the reaction frame 2, and the steel plate 18 is installed on the outer side of the box.

[0050] The box body includes a box side cover 14 and a box bottom cover 15. A box side cover 14 is installed at the front and rear ends of the box bottom cover 15. Each of the box side covers 14 is provided with a through hole. The first pipe segment structure 4 at the front end of the pipe segment ring is installed in the through hole at the front end of the box bottom cover 15, and the first pipe segment structure 4 at the rear end of the pipe segment ring is installed in the through hole at the rear end of the box bottom cover 15.

[0051] The test was conducted within a temperature-controlled chamber 1. The ground load simulator 3 was fixed to a U-shaped reaction frame 2. The side covers 14 and bottom cover 15 were directly connected via screws or bayonet fasteners. The side covers 14 were bolted to the first and last rings of segment structures 4. Sealing gaskets 11 ensured a tight seal between the first and last segments 4 and the side covers. Bolt holes were reserved along the edges of the central through-holes in the side covers 14. Nuts connected the screws 6 to the crossbeam 5 and secured them to the side covers 14, ensuring that the crossbeam 5 would not move.

[0052] At the same time, the displacement meter 9 is fixed to the crossbeam 5 and the segment structure 4 by bolts at both ends. The reaction frame 2 is directly connected to the enclosure 8 by welding or bolts. The enclosure 8 on the left and right sides of the box body are flush with the outer surface of the stratum load simulation device on the left and right sides of the box body (the outer surface of the steel plate 18). The lower surface of the stratum load simulation device 3 on the top of the box body is flush with the upper surface of the enclosure members 8 on the left and right sides of the box body. The ice sand 13 is pre-buried in the predetermined position of the sand 12. The soil pressure gauge 10 is buried around the segment structure 4. The top of the segment structure 4 is flush with the top of the stratum load simulation device 3.

[0053] There are nine stratum load simulation devices 3, one of which is installed on the inner side below the reaction frame 2 and connected to the top of the box, four of which are installed on the left side of the reaction frame 2 and the box, and the other four are installed on the right side of the reaction frame 2 and the box.

[0054] A displacement meter 9 is installed between each of the segment structures 4 and the crossbeam 5 .

[0055] The test device further includes a strain gauge, and the strain gauge is attached to the surface of the tube sheet structure 4.

[0056] The present invention also discloses a method for using a testing device for segment deformation caused by local liquefaction of sand, comprising the following steps:

[0057] Step 1: This test needs to be carried out in a temperature-controlled box. Before the test, the test device needs to be assembled. Before the experiment, the device is placed in the temperature-controlled box 1, and the sample is prepared below 0℃, and then raised to above 0℃ during the experiment.

[0058] Step 2: Align and install the box side cover 14 and the box bottom cover 15 by screws or bayonet, and open a through hole in the box side cover 14 according to the test size of the tube structure 4. Keep the sealing of the through hole joints between the tube structure 4 and the box side cover 14 throughout the whole process.

[0059] Step 3: Fix the stratum load simulation device 3 and the enclosure member 8 on the reaction frame 2 by welding or bolting, and adjust the loading position; the enclosure member 8 is flush with the outer surface of the stratum load simulation device 3 on the left and right sides of the box, and the lower surface of the stratum load simulation device 3 on the top of the box is flush with the upper surface of the enclosure member 8.

[0060] Step 4: Lay the first layer of sand and soil. The height of the sand and soil should be flush with the bottom of the through hole of the side cover 14 of the box body. During the laying of the first layer of sand and soil, bury the ice sand 13 at the predetermined position and bury the soil pressure gauge 10 in the area corresponding to the stratum load simulation device 3 to observe the magnitude of the applied soil pressure. During the laying process, it is necessary to check whether the device has sand leakage.

[0061] Step 5: Install the first segment structure 4 on the box side cover 14 with bolts and sealing glue 11, maintain the sealing of the device, and stick strain gauges on the surface of the segment structure 4. After completion, splice the next ring of segment structures 4 and strain gauges in sequence. Repeat the above operation until all the segment structures 4 used for the test are spliced. The last ring of segment structure 4 is installed on the box side cover 14 with bolts and sealing glue 11.

[0062] Step 6: Reserve bolt holes in the middle of the through holes on the front and rear side panels of the box, connect the crossbeam 5 and the screw rod 6 with bolts, and fix the screw rod 6 to the side cover 14 of the connecting box to ensure that the crossbeam 5 does not move during the test.

[0063] Step 7: Inside the segment, fix one end of the displacement meter 9 to the crossbeam 5 with a bolt, and connect the other end to the segment structure 4. Arrange displacement meters 9 on all four sides of the crossbeam 5 to measure the displacement of the segment structure 4 in different liquefaction areas from multiple directions.

[0064] Step 8: Lay the second layer of sand and soil, the height of the sand and soil is flush with the top of the segment structure 4. During the laying of the second layer of sand and soil, bury ice sand 13 at the predetermined position, and bury multiple soil pressure gauges 10 in the space area between the outer wall of the segment ring and the inner wall of the box. The buried position of each soil pressure gauge 10 corresponds to the stratum load simulation device 3 on the left and right sides of the box. Check whether there is sand leakage in the device during the laying process.

[0065] Step 9: Lay the third layer of sand and soil. The height of the sand and soil should be flush with the bottom of the stratum load simulation device 3. During the laying of the third layer of sand and soil, bury ice sand 13 at the predetermined position and bury the soil pressure gauge 10 in the corresponding area on the top of the segment structure 4. Check whether there is any sand leakage in the device during the laying process.

[0066] Step 10: After the test device is installed, before the test begins, it is necessary to check whether the control circuit of each stratum load simulation device 3 is normal to avoid malfunction during the test.

[0067] Step 11: Control the stratum load simulation device 3 to apply confining pressure to the sand, and stop loading after the value displayed by the soil pressure gauge 10 reaches the calculated value.

[0068] Step 12: After the soil confining pressure stabilizes, adjust the temperature of the temperature control box 1 to melt the ice 13 pre-buried in the sand, achieving local liquefaction of the sand. During the liquefaction process, observe the changes in the displacement meter 9 and the changes in the segment strain.

[0069] Step 13: After the test is completed, stop loading and recycle the test device as required.

[0070] The beneficial effects of the present invention are as follows: 1. The present invention is carried out in a temperature-controlled box 1, and the ice 13 is pre-buried in a predetermined position inside the sand. By adjusting the temperature, local liquefaction of the sand is achieved to simulate actual engineering; 2. The present invention adopts a jack hydraulic device to apply three-dimensional confining pressure of the soil under actual working conditions to the pipe segment, and more accurately simulates the influence of sand liquefaction on pipe segment deformation under actual working conditions; 3. The present invention buries a pressure gauge inside the sand, which can accurately measure the applied load and improve the accuracy of the test; 4. The present invention arranges a strain gauge on the surface of the pipe segment structure 4 to accurately measure the pipe segment strain caused by sand liquefaction.

[0071] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A test device for segment deformation caused by local liquefaction of sand, characterized by: The invention comprises a reaction frame (2), a plurality of stratum load simulation devices (3), a plurality of segment structures (4), a crossbeam (5), a plurality of displacement meters (9), an earth pressure meter (10), a box body, and an ice smoothie (13). The reaction frame (2) is installed on the periphery of the box body, a plurality of stratum load simulation devices (3) are installed on the inner side of the reaction frame (2), and the stratum load simulation devices (3) are connected to the box body; a plurality of segment structures (4) are installed together in sequence to form a segment ring, and the segment ring is installed in the box body, and the The front and rear ends of the segment ring are respectively connected to the box body; the crossbeam (5) is installed in the segment ring; the displacement meter (9) is installed between the crossbeam (5) and the inner wall of the segment ring; the space between the outer wall of the segment ring and the inner wall of the box body is used for laying sand (12); the ice (13) is buried at a predetermined position in the sand (12); the soil pressure meter (10) is buried in the sand (12); the soil pressure meter (10) is buried at a position corresponding to the stratum load simulation device (3).

2. The test device according to claim 1, characterized in that: The stratum load simulation device (3) comprises a jack (16), a distribution beam (17), and a steel plate (18); the jack (16) is mounted on the distribution beam (17); the distribution beam (17) is mounted on the steel plate (18); the jack (16) is mounted on the inner side of the reaction frame (2); and the steel plate (18) is mounted on the outer side of the box.

3. The test device according to claim 2, characterized in that: The box body comprises a box body side cover (14) and a box body bottom cover (15). A box body side cover (14) is respectively installed at the front and rear ends of the box body bottom cover (15). Each of the box body side covers (14) is provided with a through hole. The first tube segment structure (4) at the front end of the tube segment ring is installed in the through hole at the front end of the box body bottom cover (15), and the first tube segment structure (4) at the rear end of the tube segment ring is installed in the through hole at the rear end of the box body bottom cover (15).

4. The test device according to claim 2, characterized in that: There are nine stratum load simulation devices (3), one of which is installed on the inner side below the reaction frame (2) and connected to the top of the box body, four of which are installed between the reaction frame (2) and the left side of the box body, and the other four are installed between the reaction frame (2) and the right side of the box body.

5. The test device according to claim 1, characterized in that: A displacement meter (9) is installed between each of the tube segment structures (4) and the crossbeam (5); and the reaction frame (2) is a U-shaped reaction frame.

6. The test device according to claim 3, characterized in that: The test device also includes a fixing device, and the crossbeam (5) is installed in the tube ring through the fixing device; the fixing device includes a screw (6) and a nut, and a fixing hole (7) is reserved on the edge of the through hole in the middle of the box side cover (14). One end of the screw (6) is installed on the crossbeam (5), and the other end of the screw (6) is installed in the reserved fixing hole (7) and is locked by the nut.

7. The test device according to claim 1, characterized in that: The test device also includes a strain gauge, and the strain gauge is attached to the surface of the pipe sheet structure (4); the test device also includes a protective component (8), and one of the protective components (8) is installed between the two sides of the top of the box body and the reaction frame (2).

8. The test device according to claim 3, characterized in that: The test device further comprises a sealing gasket (11), one sealing gasket (11) being installed between the first tube segment structure (4) at the front end of the tube segment ring and the through hole at the front end of the box bottom cover (15), and one sealing gasket (11) being installed between the first tube segment structure (4) at the rear end of the tube segment ring and the through hole at the rear end of the box bottom cover (15); the box side cover (14) and the box bottom cover (15) are directly connected by screws or bayonet.

9. The test device according to claim 1, characterized in that: The test device needs to be carried out in a temperature control box (1). Before the test is carried out, the test device needs to be assembled. Before the experiment, the test device is placed in the temperature control box (1).

10. A method for using a testing device for segment deformation caused by local liquefaction of sand, characterized in that: This involves performing the following steps: Step 1: Assemble the test device. Place the device in a temperature-controlled box (1) before the experiment. Prepare samples at a temperature below 0°C, and then raise the temperature to above 0°C during the experiment. Step 2: Align the box side cover (14) and the box bottom cover (15) with screws or bayonets, and open a through hole in the box side cover (14) according to the test size of the tube structure (4). During the whole process, the sealing of the through hole joints on the tube structure (4) and the box side cover (14) is maintained; Step 3: Fix the stratum load simulation device (3) and the enclosure member (8) on the reaction frame (2), and adjust the loading position; the enclosure members (8) on the left and right sides of the box are flush with the outer surfaces of the stratum load simulation device on the left and right sides of the box, and the lower surface of the stratum load simulation device (3) on the top of the box is flush with the upper surfaces of the enclosure members (8) on the left and right sides of the box; Step 4: Lay the first layer of sand and soil, the height of the sand and soil is flush with the bottom of the through hole of the box side cover (14). During the laying of the first layer of sand and soil, bury the ice (13) at the predetermined position, and bury the soil pressure gauge (10) in the area corresponding to the stratum load simulation device (3) to observe the magnitude of the applied soil pressure. During the laying process, it is necessary to check whether the device has sand leakage; Step 5: Install the first segment structure (4) on the box side cover (14) by means of bolts and sealing glue (11), maintain the sealing of the device, and affix strain gauges on the surface of the segment structure (4). After completion, the next ring of segment structures (4) and strain gauges are sequentially spliced. Repeat the above operation until all the segment structures (4) used for the test are spliced. The last ring of segment structures (4) is installed on the box side cover (14) by means of bolts and sealing glue (11); Step 6: Reserve bolt holes in the middle of the through holes on the front and rear side panels of the box body, connect the crossbeam (5) and the screw rod (6) with bolts, and connect the screw rod (6) to the side cover (14) of the connecting box body to ensure that the crossbeam (5) will not be displaced during the test; Step 7: Inside the segment, a displacement meter (9) is fixed to the crossbeam (5) with one end by bolts, and the other end is connected to the segment structure (4). Displacement meters (9) are arranged on the four sides of the crossbeam (5) to measure the displacement of the segment structure (4) in different liquefied areas from multiple directions. Step 8: Lay a second layer of sand, the height of the sand being flush with the top of the segment structure (4). During the laying of the second layer of sand, bury ice (13) at a predetermined position, bury a plurality of earth pressure gauges (10) in the space between the outer wall of the segment ring and the inner wall of the box, the buried position of each earth pressure gauge (10) corresponding to the stratum load simulation device (3) on the left and right sides of the box, and check whether the device has sand leakage during the laying process; Step 9: Lay the third layer of sand and soil, the height of the sand and soil is flush with the bottom of the stratum load simulation device (3). During the laying of the third layer of sand and soil, bury ice sand (13) at the predetermined position and bury the soil pressure gauge (10) in the corresponding area on the top of the pipe segment structure (4). During the laying process, check whether the device has sand leakage; Step 10: After the test device is installed, before the test begins, check whether the control circuit of each stratum load simulation device (3) is normal; Step 11: Control the stratum load simulation device (3) to apply confining pressure to the sand, and stop loading after the value displayed by the soil pressure gauge (10) reaches the calculated value; Step 12: After the soil confining pressure stabilizes, the temperature of the temperature control box (1) is adjusted to melt the ice (13) pre-buried in the sand, thereby achieving local liquefaction of the sand. During the liquefaction process, the changes in the displacement meter (9) and the changes in the segment strain are observed; Step 13: After the test is completed, stop loading and recycle the test device as required.

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