Underground pipeline visual test system and method for simulating differential load effect

Abstract

The invention discloses a buried pipeline visual test system and method for simulating a differential load effect, and belongs to the technical field of geotechnical engineering. The soil body model is filled in the test soil body container, and a test pipeline model is buried in the soil body model; the difference loading device is fixed above the upper sealing cover of the test soil body container, the difference loading device comprises a first servo electric cylinder and a second servo electric cylinder, and loading rods of the first servo electric cylinder and the second servo electric cylinder penetrate through a preset hole channel of the upper sealing cover to act on the lower soil body and the test pipeline model; the first servo electric cylinder and the second servo electric cylinder are different in specification, and the loading rate is independent and controllable; and the monitoring and data acquisition system comprises a stress sensor, a strain sensor and a pore water pressure sensor which are buried in the soil body model, and a pressure sensor and a displacement sensor which are arranged around the test pipeline model. According to the invention, the actual stress condition of the buried pipeline in the actual working condition can be better simulated.

Description

Technical Field

[0001] This invention relates to a visualization testing system and method for simulating differential loads on buried pipelines, belonging to the field of geotechnical engineering technology. Background Technology

[0002] As a core infrastructure, buried pipelines often bear non-uniform loads in actual engineering projects. On the one hand, differences in the thickness of the soil covering the pipeline and its surroundings, the local effects of ground traffic loads, and the uneven distribution of surrounding buildings create significant differential load gradients, causing the pipeline to bear differentiated pressures along the axial or radial direction. On the other hand, the uneven physical and mechanical properties of the soil itself exacerbate the non-uniformity of load transmission, further leading to localized stress concentration and uneven settlement of the pipeline. Therefore, in-depth research on the stress mechanism of buried pipelines under non-uniform loads effectively fills the technical gaps in the accuracy of differential load simulation and the depth of visual monitoring of existing devices, providing reliable experimental support for revealing and optimizing pipeline structural design and formulating prevention and control measures in actual engineering projects.

[0003] Existing test devices mostly use a single cyclic loading method, which cannot accurately reproduce the load difference between the pipeline and the surrounding soil, and it is difficult to simulate such differentiated loads. At the same time, the existing devices have insufficient visualization monitoring capabilities, and mostly rely on single-point sensors to record data, making it difficult to capture the dynamic process of pipeline deformation, soil displacement field evolution and pipe-soil interface interaction through intuitive images. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a visual testing system and method for simulating differential loads on buried pipelines, which can better simulate the actual stress conditions of buried pipelines under actual working conditions.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a visual testing system for simulating differential loads on buried pipelines, comprising: The test soil container has a movable upper cover at the top and a transparent baffle on the side. The upper cover has a wiring adapter plate, and the transparent baffle has a water inlet hole at the top and a drainage hole at the bottom. A soil model, wherein the soil model is filled inside the test soil container, and a test pipe model is embedded therein; A differential loading device is fixed above the upper cover of the test soil container. The differential loading device includes a first servo cylinder and a second servo cylinder. The loading rods of the first servo cylinder and the second servo cylinder pass through the preset channel of the upper cover and act on the soil below and the test pipe model. The first servo cylinder and the second servo cylinder have different specifications and the loading rate is independently controllable. The monitoring and data acquisition system includes stress sensors, strain sensors, and pore water pressure sensors embedded in the soil model, as well as pressure sensors and displacement sensors around the test pipe model. The lines of the monitoring and data acquisition system are all gathered and led out through the line adapter plate of the upper cover to connect to an external data acquisition system. A high-speed camera is installed on the outside of the tempered glass transparent baffle, with its lens aimed at the internal test pipe model and soil area.

[0006] Furthermore, it also includes a support device, which is set at the bottom of the test soil container and includes a three-legged steel bracket and a semi-circular rubber pad placed on the platform of the three-legged steel bracket. The rubber pad is set at the bottom of the test device, and the size of the rubber pad matches the bottom diameter of the test soil container.

[0007] Furthermore, the transparent baffle is made of rectangular tempered glass.

[0008] Furthermore, the transparent baffle is reinforced with a steel grid on its exterior.

[0009] Furthermore, the test soil container is a semi-cylindrical hollow device.

[0010] Furthermore, the upper cover is screwed to the side wall of the test soil container by a number of evenly spaced bolts.

[0011] Furthermore, an O-ring is provided at the joint surface between the upper cover and the test soil container.

[0012] Furthermore, both the inlet and outlet are equipped with water valves. The inlet is connected to an external water pump via a pipeline, and the outlet is connected to an external drainage system via a pipeline.

[0013] Furthermore, the high-speed camera, in conjunction with DIC analysis technology, identifies the deformation of the test pipeline model under differential loads.

[0014] Secondly, the present invention provides a testing method for a visual testing system for simulating differential loads on buried pipelines according to any one of the foregoing claims, comprising: Open the top cover of the test soil container, fill the container with soil in layers according to the preset density, and at the same time bury the test pipe model during the filling process. Stress sensors, strain sensors, and pore water pressure sensors are placed in the soil, and pressure sensors and displacement sensors are placed around the test pipe model. Pass all sensor connection lines through the wiring adapter plate on the top cover and connect them to the external data acquisition system; Close the upper cover, fix the differential loading device on the upper cover, and adjust the positions of the first servo cylinder and the second servo cylinder. Open the water valve of the inlet hole and inject water into the soil through the water injection system. At the same time, monitor the reading of the pore water pressure sensor. When the preset pore water pressure value is reached, stop the water injection and close the water valve. A high-speed camera was mounted on the outside of the transparent baffle, and its position and focus were adjusted to ensure that it was clearly focused on the test pipe model and the surrounding soil area. The differential loading device is activated, and the first and second servo cylinders operate according to the preset program to apply differential loads to the test pipe model and the surrounding soil. During this process, the data from all sensors is recorded in real time through the data acquisition system, and the deformation images of the test pipe model and the soil are continuously recorded by a high-speed camera. After the test, loading and data recording were stopped, the top cover was opened, and the soil sample was taken out for analysis.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention provides a visualization testing system and method for simulating differential loads on buried pipelines. It achieves precise load gradient control between the test pipeline model and the surrounding soil through two servo electric cylinders of different specifications. With the help of sensors and high-speed cameras, it captures the strain distribution of the test pipeline model, the evolution of the displacement field of the surrounding soil, and the settlement deformation law in real time under differential loads, which can better simulate the actual stress conditions of buried pipelines in actual working conditions. Attached Figure Description

[0016] Figure 1 This is a front view of the buried pipeline visualization test system for simulating differential loads provided in an embodiment of the present invention; Figure 2 This is a side view of the buried pipeline visualization test system for simulating differential loads provided in an embodiment of the present invention. Figure 3 This is a top view of the buried pipeline visualization test system for simulating differential loads provided in an embodiment of the present invention.

[0017] In the diagram: 1. Test soil container; 2. Rubber pad; 3. Tripod steel support; 4. Transparent baffle; 5. High-speed camera; 6. First servo electric cylinder; 7. Drainage hole; 8. Water inlet hole; 9. Top cover; 10. First bolt; 11. Line adapter plate; 12. Second bolt; 13. Test pipeline model; 14. Second servo electric cylinder. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0019] Example 1: This example introduces a visual testing system for simulating differential loads on buried pipelines, including: The soil model contains an experimental pipe model 13, a stress sensor, a strain sensor, and a pore water pressure sensor.

[0020] The test soil container 1 is a semi-cylindrical container with an open top. The semi-circular top cover 9 is equipped with an air compressor circuit adapter plate 11. The rectangular side is a tempered glass transparent baffle 4. The upper part of the transparent baffle 4 is equipped with a water inlet hole 8 and the lower part is equipped with a drainage hole 7. The outside is equipped with a steel grid to reinforce the transparent baffle 4 and ensure the visualization of the test process.

[0021] The test pipeline model 13 is placed in the soil, and displacement sensors and pressure sensors are buried around it to realize real-time monitoring of pipeline deformation and displacement of the surrounding soil.

[0022] The differential loading device is a movable device in which two servo electric cylinders of different specifications are fixed above the model box by a loading frame, and the loading rate is controllable.

[0023] The support device includes a three-legged steel bracket 3 with a circular platform and a semi-circular rubber pad 2. The dimensions of the circular platform and the semi-circular rubber pad 2 are consistent with the bottom diameter of the test device. The semi-circular rubber pad 2 is set at the bottom of the test device to buffer the equipment vibration caused during the application of load.

[0024] The monitoring and data acquisition system includes stress sensors, strain sensors, and pore water pressure sensors embedded in the soil, as well as pressure sensors and strain gauges around the test pipe model 13. All these components are connected to the external data acquisition system via the wiring adapter 11 on the upper cover 9, enabling real-time data transmission and recording. A high-speed camera 5 is mounted on the outside of the transparent baffle 4, aimed at the test pipe model 13 and the surrounding soil area, to scan and record in real-time the deformation changes of the test pipe model 13 and the displacement changes of the surrounding soil during the test.

[0025] The test soil container 1 is a semi-cylindrical hollow device with a movable upper cover 9. After the soil is filled, the upper cover 9 can be screwed to the side wall of the container using bolts at even intervals, and the interface is sealed with O-ring rubber seals. The transparent baffle 4 of the test soil container 1 is provided with a water inlet hole 8 and a water valve for connecting the water pump pipeline; the lower part of the transparent baffle 4 is provided with a drain hole 7 and a water valve for connecting the drain pipe outside the test device to drain water and change the pore water pressure of the soil.

[0026] The rubber pads are placed at the bottom of the test device to effectively reduce equipment vibration during the application of loads, which helps to improve test accuracy.

[0027] Stress sensors, strain sensors, and pore water pressure sensors are embedded inside the soil model. Pressure sensors and strain gauge connection lines are embedded around the test pipe model 13. The sensor lines are connected to the external acquisition system via an adapter plate.

[0028] The specific steps for applying the buried pipeline visualization testing system for simulating differential loads provided in this embodiment are as follows: S1. Set up the support device and arrange the test soil container 1. Open the upper cover 9 and fill the container with soil evenly according to the preset density. Then, bury the test pipe model 13 in the soil and install strain sensors, stress sensors, and pore water pressure sensors in the soil. Bury displacement sensors and pressure sensor connection lines around the test pipe model 13.

[0029] S2. Pass the sensor's wiring through the adapter plate of the upper cover 9 and connect it to the data acquisition system outside the container device.

[0030] S3. Tighten the bolts between the upper cover 9 and the test soil container 1, and seal the container with an O-ring.

[0031] S4. Arrange the loading system and tighten the bolts between the loading system device and the test soil container 1.

[0032] S5. Open the water valve of the inlet hole 8 and monitor the pore pressure reading of the pore water pressure sensor in real time. After the preset pore pressure is reached, stop water injection and close the water valve.

[0033] S6. Place a high-speed camera outside the model box and point the camera at the tempered glass transparent baffle 4 to record the deformation changes of the test pipe model 13 and the displacement changes of the surrounding soil.

[0034] S7. Start the loading device. During the test, the stress, strain, and soil displacement experienced by the pipeline can be recorded by the data acquisition system. After the test, open the upper cover 9 and remove the soil sample.

[0035] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0036] like Figures 1 to 3 As shown, a visual testing system for simulating differential loads on buried pipelines includes a test soil container 1, a differential loading device, a test pipeline model 13, and a support device.

[0037] The test soil container 1 is horizontally supported on a support device. The support device includes a triangular steel bracket 3 and a semi-circular rubber pad 2. The test soil container 1 is a semi-cylindrical container, including a movable top cover 9 and a tempered glass transparent baffle 4 (to ensure visibility of the test process, and is reinforced with a steel grid on the outside).

[0038] The tempered glass transparent baffle 4 of the test soil container 1 is equipped with a water inlet 8 and a drain 7. The water inlet 8 has a water valve and is connected to a water pump via an extension pipe, allowing water to be injected into the soil before the test to adjust the pore water pressure. The drain 7 has a water valve for draining water as needed for the test. The test pipeline model 13 is embedded in the soil within the test soil container 1. The upper cover 9 is tightened to the test soil container 1 with bolts 10 and sealed with O-rings. Water is slowly injected into the soil through the water inlet 8, and the pore water pressure sensor readings are monitored in real time. The pore water pressure is adjusted to simulate the physical and mechanical state of the in-situ soil. A high-speed camera 5 can be mounted on the outside of the tempered glass transparent baffle 4, aimed at the test pipeline model 13 and the surrounding soil area, to record the deformation of the test pipeline model 13 and changes in soil displacement. The semi-circular rubber pad 2 of the support device matches the bottom diameter of the test soil container 1, buffering vibrations generated during loading and preventing sensor damage or measurement signal distortion due to vibration.

[0039] In this embodiment of the invention, the differential loading device is movable, and its core components are two first servo electric cylinders 6 and second servo electric cylinders 14 of different specifications. The output force range, stroke, and response speed of the two cylinders differ by a preset amount. They are fixed to the upper cover 9 at a preset hole by a loading frame, and a stable connection is achieved by tightening bolts 12. The position of the loading frame can be finely adjusted according to experimental requirements to ensure that the two servo electric cylinders correspond to the target loading areas above and around the test pipeline model 13, forming a precise load gradient. The loading rate of the electric cylinders can simulate the load change rate caused by differences in traffic loads or ground loads, thereby reproducing the non-uniform load conditions experienced by pipelines in actual engineering.

[0040] In this embodiment of the invention, the test pipeline model 13 is a model simulating a buried pipeline in actual engineering. Its material is selected based on the test requirements, using PVC material with similar mechanical properties to the actual pipeline, to ensure that the deformation and stress response of the pipeline during the test are similar to the prototype pipeline. The buried position of the test pipeline model 13 needs to be precisely positioned, centered along the axis of the test soil container 1, with the pipeline axis parallel to the tempered glass transparent baffle 4, facilitating the high-speed camera to capture the deformation details of the entire pipeline section through the transparent baffle. The outer wall of the pipeline is pre-treated, and combined with DIC analysis technology, the deformation of the pipeline under differential loads can be more accurately identified. The test pipeline model 13 adopts an integral structure, with a certain gap reserved between both ends of the test pipeline model 13 and the inner wall of the test soil container 1 to avoid boundary effects affecting the free deformation of the pipeline. The gaps are filled with filler of the same properties as the surrounding soil to ensure that the soil's constraint conditions on the pipeline are consistent with reality. The test pipeline model 13 can accurately reproduce the physical characteristics and stress environment of actual buried pipelines, and can also work with sensors and visualization systems to fully capture the deformation, strain and stress state under different loads, providing a reliable test platform for revealing the damage mechanism of pipelines under non-uniform loads.

[0041] In this embodiment of the invention, the support device includes a three-legged steel bracket 3 with a circular platform and a semi-circular rubber pad 2. The dimensions of the circular platform and the semi-circular rubber pad 2 are consistent with the bottom diameter of the test device. The semi-circular rubber pad 2 is set at the bottom of the test device to buffer the equipment vibration caused by applying differential loads. This avoids damage to various sensors in the soil and around the pipeline due to vibration, and also prevents the vibration of the test device from causing distortion of measurement signals, thus ensuring the accuracy of the test data.

[0042] Example 2: This example provides a test method for a buried pipeline visualization test system simulating differential loads according to any one of the examples in Example 1, comprising: Open the top cover 9 of the test soil container 1, fill the container with soil in layers according to the preset density, and at the same time, bury the test pipe model 13 during the filling process. Stress sensors, strain sensors, and pore water pressure sensors are installed in the soil, and pressure sensors and displacement sensors are installed around the test pipe model 13. All sensor connection lines are passed through the line adapter plate 11 of the upper cover 9 and connected to the external data acquisition system; Close the upper cover 9, fix the differential loading device on the upper cover 9, and adjust the positions of the first servo cylinder 6 and the second servo cylinder 14. Open the water valve of water inlet 8 and inject water into the soil through the water injection system. At the same time, monitor the reading of the pore water pressure sensor. When the preset pore water pressure value is reached, stop the water injection and close the water valve. A high-speed camera 5 is mounted on the outside of the transparent baffle 4. Its position and focal length are adjusted so that it is clearly focused on the test pipe model 13 and the surrounding soil area. The differential loading device is activated, and the first servo cylinder 6 and the second servo cylinder 14 operate according to the preset program to apply differential loads to the test pipe model 13 and the surrounding soil. During this process, the data of all sensors are recorded in real time through the data acquisition system, and the deformation images of the test pipe model 13 and the soil are continuously recorded by the high-speed camera 5. After the test, stop loading and data recording, open the top cover 9, and take out the soil sample for analysis.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A buried pipeline visual testing system simulating the effect of differential loading, characterized in that, The utility model relates to a soil pipe model test device, including: Test soil container (1), the upper portion of test soil container (1) is equipped with movable upper cover (9), is equipped with transparent baffle (4) on the side, is equipped with line adapter disc (11) on upper cover (9), the upper portion of transparent baffle (4) is equipped with water inlet hole (8), and the lower portion is equipped with drainage hole (7); Soil model, the soil model is filled in test soil container (1) wherein, is buried with test pipe model (13); Difference loading device, the difference loading device is fixed on the upper cover (9) of test soil container (1), and the difference loading device includes first servo cylinder (6) and second servo cylinder (14), and the loading rod of first servo cylinder (6) and second servo cylinder (14) passes through the preset hole of upper cover (9) and acts on the soil below and test pipe model (13), and first servo cylinder (6) and second servo cylinder (14) are different in specification and independently controllable in loading rate; Monitoring and data acquisition system, including stress sensor, strain sensor, pore water pressure sensor buried in soil model and pipe surrounding pressure sensor and displacement sensor, the line of monitoring and data acquisition system is all gathered and is led out through the line adapter disc (11) of upper cover (9), is connected to external data acquisition system; High-speed camera (5), the high-speed camera (5) is equipped on the outside of the toughened glass transparent baffle (4), and the lens thereof is aimed at the test pipe model (13) and soil area inside.

2. The buried pipeline visualizing test system simulating the action of differential load according to claim 1, characterized in that, It further includes a supporting device arranged at the bottom of the test soil container (1), which includes a tripod steel support (3) and a semicircular rubber pad (2) arranged on the table top of the tripod steel support (3). The rubber pad (2) is arranged at the bottom of the test device, and the size of the rubber pad (2) matches the diameter of the bottom of the test soil container (1).

3. The buried pipeline visualizing test system simulating the action of differential loads according to claim 1, characterized in that, The transparent baffle (4) is a rectangular toughened glass material.

4. The buried pipeline visualizing test system simulating the action of differential loads according to claim 1, characterized in that, The transparent baffle (4) is externally reinforced with a steel grid.

5. The buried pipeline visualizing test system simulating the effect of differential load according to claim 1, characterized in that, The test soil container (1) is a semicylindrical hollow device.

6. The buried pipeline visualizing test system simulating the action of differential loads according to claim 1, characterized in that, The upper cover (9) is fixed with the side wall of the test soil container (1) by a plurality of evenly spaced bolts (10).

7. The buried pipeline visualizing test system simulating the action of differential loads according to claim 6, characterized in that, The upper cover (9) and the test soil container (1) are provided with an O-shaped rubber sealing ring at the joint surface.

8. The buried pipeline visualizing test system simulating the action of differential loads according to claim 1, characterized in that, The water inlet hole (8) and the drainage hole (7) are both provided with water valves. The water inlet hole (8) is connected with an external water injection pump through a pipeline, and the drainage hole (7) is connected with an external drainage system through a pipeline.

9. The buried pipeline visualizing testing system simulating the action of differential loads according to claim 1, characterized in that, The high-speed camera (5) cooperates with the DIC analysis technology to identify the deformation of the test pipe model (13) under the action of the differential load.

10. A method of testing a buried pipeline visualisation test system simulating the effect of differential loading according to any one of claims 1 to 9, characterised in that, Including: Open the upper cover (9) of the test soil container (1), fill the soil in the container in layers according to the preset density, bury the test pipe model (13) during the filling process, and arrange the stress sensor, strain sensor, and pore water pressure sensor in the soil, and arrange the pressure sensor and displacement sensor around the test pipe model (13); Connect all the sensor wires through the wire adapter plate (11) of the upper cover (9) and connect to the external data acquisition system; Close the upper cover (9), fix the differential loading device on the upper cover (9), and adjust the positions of the first servo cylinder (6) and the second servo cylinder (14); Open the water valve of the water inlet hole (8), inject water into the soil through the water injection system, and monitor the reading of the pore water pressure sensor at the same time. When the preset pore water pressure value is reached, stop injecting water and close the water valve; Set up a high-speed camera (5) outside the transparent baffle (4), adjust its position and focal length, and make it clearly focus on the test pipe model (13) and the surrounding soil area; Start the differential loading device, and the first servo cylinder (6) and the second servo cylinder (14) operate according to the preset program to apply differential load to the test pipe model (13) and the surrounding soil. In this process, the data of all sensors are recorded in real time through the data acquisition system, and the deformation image of the test pipe model (13) and the soil is continuously recorded through the high-speed camera (5); After the test is completed, stop loading and data recording, open the upper cover (9), and take out the soil sample for analysis.

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