A testing device and method for the bending stiffness attenuation law of a bell and spigot pipeline joint

Abstract

The application provides a testing device and method for the bending stiffness attenuation law of a socket pipeline joint, which can obtain the bending stiffness attenuation law of the socket pipeline joint, and has the following beneficial effects: (1) four fixed supports are vertically provided with screw holes at every interval, the specific height of the supporting I-beam can be adjusted according to the size of the test pipeline diameter, various sizes of pipelines can be detected, and the application range is wide; (2) the top of the loading I-beam is provided with four screw holes for fixing with the loading plate, which can avoid the side sliding and tilting of the loading I-beam during loading; (3) the bending moment value of the cross section of the socket pipeline joint in the test can be obtained by two methods, one is to calculate the bending moment value of the cross section of the socket pipeline joint from the strain, and the other is to calculate the bending moment value of the cross section of the socket pipeline joint from the pressure value displayed by the weighing sensor, the bending moment values obtained by the two methods can be compared, the result is more accurate and more persuasive.

Description

Technical Field

[0001] This invention relates to a testing device and method for pipeline connection strength, specifically to a testing device and method for the attenuation law of bending stiffness of socket-type pipeline joints. Background Technology

[0002] As underground pipeline systems become increasingly sophisticated, the external conditions encountered during pipeline construction also become more complex. Due to the relatively concealed nature of urban drainage pipeline projects and the complex underground environment, they are susceptible to corrosion from various surrounding chemicals during construction and use, making their damage difficult to detect. Early pipeline laying technologies were not mature, and coupled with long-term operation, drainage pipelines are highly prone to failure and damage.

[0003] Therefore, conducting indoor tests on the mechanical properties of socket joints, exploring their bending mechanical properties and failure mechanisms, analyzing the corresponding mechanical laws, and applying them to the structural design and construction of socket pipelines to extend pipeline service life are of great significance for reducing the operating costs and construction risks of underground pipelines. Summary of the Invention

[0004] The first objective of this invention is to provide a testing device for the attenuation law of bending stiffness of socket-type pipeline joints, addressing the aforementioned technical problems.

[0005] Therefore, the above-mentioned objective of the present invention is achieved through the following technical solution: A testing device for the bending stiffness attenuation law of socket-type pipeline joints includes: a fixing module, a loading module, a pipeline module, and a testing module; The fixing module includes a base, four supports on the base, two supporting I-beams between the supports, and a pipeline clamp on the supporting I-beams, wherein the pipeline clamp holds a socket-type pipeline. The loading module includes a manual hydraulic control device, a reaction frame, an upper connecting plate, a lower connecting plate, a loading plate, and a loading I-beam. The manual hydraulic control device includes a hydraulic jack and a manual pump, with the manual pump connected to the hydraulic jack via an oil pipe. The reaction frame is mounted on the base of the fixed module, with a lower connecting plate in the center for fixing the hydraulic jack base. The lower connecting plate and the upper connecting plate are fixed to the reaction frame. The lower head of the hydraulic jack is provided with a weighing sensor, a loading plate, and a loading I-beam from top to bottom. The two ends of the loading I-beam are mounted on the socket-type pipeline, and the contact loading points between the two ends of the loading I-beam and the socket-type pipeline are symmetrically arranged on both sides of the joint of the socket-type pipeline. The pipeline module includes two pipeline sections, one end of which is a socket and the other end of which is a spigot. The socket of one pipeline section is matched with the spigot of the other pipeline section, and a rubber ring is installed between the spigot and the matched socket. The detection module includes a load cell, an angle sensor, a strain gauge, and a strain meter. The strain gauge is installed on the outside of the spigot and the inside of the socket at the joint of the two pipeline sections. The load cell is welded between the hydraulic jack and the loading plate. The strain gauge and load cell are connected to the strain meter. A pair of angle sensors are symmetrically arranged on the outer surface of the pipeline on both sides of the joint. The load cell is used to measure the applied pressure. In conjunction with the strain meter, it can obtain the bending moment at the joint section. This value can be compared with the bending moment values ​​obtained by the strain gauge and strain meter for more accurate results. The strain gauge and strain meter are used to measure the strain at the joint of the two pipeline sections to obtain the bending moment at the joint section. Through relevant software and in conjunction with the angle sensor, the rotation angle at the joint between the pipeline spigot and the pipeline socket can be obtained.

[0006] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions: As a preferred technical solution of the present invention: the fixed support is provided with multiple rows of screw holes from top to bottom in the vertical direction to adjust the distance between the supporting I-beam and the base according to the test requirements.

[0007] As a preferred technical solution of the present invention: the pipeline clamp includes a pipe seat and a pipe clamp, the pipe seat is fixed to the supporting I-beam, the pipe seat and the pipe clamp are fixed together by bolts, and the pipe seat and the pipe clamp hold the socket-type pipeline.

[0008] As a preferred technical solution of the present invention: two fan-shaped steel plates are welded to the bottom ends of the loading I-beam, and the fan-shaped diameter of the fan-shaped steel plates is adapted to the outer diameter of the socket-type pipeline.

[0009] As a preferred embodiment of the present invention, the angle sensor is mounted on the pipeline via a mounting plate, or it can be directly pasted onto the pipeline.

[0010] As a preferred technical solution of the present invention: the strain gauge on the inner surface of the socket and the strain gauge on the outer surface of the spigot are on the same longitudinal section.

[0011] As a preferred technical solution of the present invention: the strain gauges on the inner surface of the socket and the strain gauges on the outer surface of the spigot are arranged at angles of 0°, 45°, 90°, 135°, 180°, 225°, 270° and 315° in a clockwise circumferential direction starting from the top of the pipeline, so as to obtain more strain data and make the measurement results more accurate.

[0012] Another objective of this invention is to provide a testing method for the testing device for the attenuation law of the bending stiffness of the socket-type pipeline joint as described above.

[0013] Therefore, the above-mentioned objective of the present invention is achieved through the following technical solution: The test method for the test device for the bending stiffness attenuation law of socket-type pipeline joints described above includes the following steps: S1. Determine the positions of the four supports and the height of the supporting I-beams according to the dimensions of the socket-type pipeline used in the test, and fix the supporting I-beams to the supports with bolts; S2. Place strain gauges on the outside of the spigot and the inside of the socket of the spigot-and-socket joint. Also, attach strain gauges at 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° from the top of the pipe on the inside of the socket and the outside of the spigot. After the spigot is inserted into the socket, the strain gauges on the socket and spigot must be placed on the same longitudinal section. To connect the pipelines, install a rubber ring on the outside of the spigot of one pipeline section and insert it into the socket of the other pipeline section. S3. Fix the pipe seat of the pipeline clamp to the supporting I-beam, place the connected pipeline on the pipe seat, and connect the pipe seat to the pipe clamp with bolts to fix the pipeline. Place the loading I-beam on the pipeline and bolt it to the loading plate above it; Then, the angle sensor is bolted to the mounting plate, and the mounting plate is pasted onto the pipe body at opposite positions on both sides of the socket-type pipe joint, directly above the pipe body; The strain gauge, load cell, and strain meter are connected together, and the strain meter is connected to a computer to obtain the strain and the applied pressure. S4. Press the manual pump and use staged loading. Record the angle and strain value after each pressure stabilizes until the pipeline joint is completely destroyed. Plot the bending moment versus rotation curve at the socket-type pipe joint to determine the critical bending moment value. ; S5. Take socket-type pipelines and rubber rings of the same material and size, and repeat steps S1 to S3. Staged loading was applied, with the maximum bending moment controlled at 0.2. Record the rotation angle and strain under each pressure level, then remove the pressure, repeat the graded loading step multiple times, and finally plot the curve between the bending moment and rotation angle of the socket pipe joint under cyclic loading. S6, adjust the maximum loaded bending moment to 0.4. 0.6 0.8 Repeat step S5 to study the attenuation law of the bending stiffness of the socket-type pipeline joint.

[0014] This invention provides a testing device and method for determining the bending stiffness attenuation law of socket-type pipeline joints. This method can obtain the bending stiffness attenuation law of socket-type pipeline joints and also has the following beneficial effects: (1) The four fixed supports are provided with screw holes at intervals (e.g., 10 cm) in the vertical direction. The specific height of the supporting I-beam can be adjusted according to the diameter of the test pipeline. It can test pipelines of various sizes and has a wide range of applications.

[0015] (2) The bottom sides of the loading I-beam are welded with fan-shaped steel plates that are compatible with the diameter of the socket-type pipeline, which facilitates loading. The top of the loading I-beam is provided with four screw holes for fixing with the loading plate, thereby fixing with the weighing sensor and hydraulic jack, which can prevent the loading I-beam from sliding or tilting during loading. (3) The bending moment value of the socket-type pipeline joint section can be obtained in two ways during the test. One is to obtain the bending moment value of the socket-type pipeline joint section by strain calculation; the other is to calculate the bending moment value of the socket-type pipeline joint section by the pressure value displayed by the weighing sensor. The bending moment values ​​obtained by the two methods can be compared to make the results more accurate and convincing. Attached Figure Description

[0016] Figure 1 A perspective view of the testing device for the bending stiffness attenuation law of the socket-type pipeline joint provided by the present invention. Figure 2 A 3D view of the pipeline clamp; Figure 3 This is a cross-sectional view of strain gauges arranged on a pipeline joint. Figure 4a A diagram showing the arrangement of strain gauges on the spigot of a pipeline joint; Figure 4b This diagram illustrates the arrangement of strain gauges on the socket of a pipeline joint. Figure 5 A perspective view of the mounting plate for the angle sensor; Figure 6 A 3D view of the loaded I-beam; Figure 7 A three-dimensional diagram supporting the I-beams; The diagram shows: 1-base; 2-support; 3-supporting I-beam; 4-pipe seat; 5-reaction frame; 6-upper connecting plate; 7-lower connecting plate; 8-hydraulic jack; 9-weighing sensor; 10-loading plate; 11-loading I-beam; 12-socket-type pipeline; 13-manual pump; 14-oil pipe; 15-pipe clamp; 16-mounting plate; 17-angle sensor; 18-rubber ring; 19-strain gauge; 20-slot; 21-socket; 22-strain gauge; 23-screw hole; 24-sector-shaped steel plate. Detailed Implementation

[0017] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Reference Figures 1-7 A testing device for the bending stiffness attenuation law of socket-type pipeline joints includes: a fixing module, a loading module, a pipeline module, and a detection module; The fixing module includes a base 1, with four supports 2 fixedly connected symmetrically to the base 1. Two supports 2 are bolted to the supporting I-beam 3. The height of the supporting I-beam 3 can be adjusted according to test requirements. The supporting I-beam has four symmetrical screw holes for fixing the pipe clamp's pipe seat 4.

[0019] The pipeline clamp includes a pipe seat 4 and a pipe clamp 15. The base plate of the pipe seat 4 has four screw holes, the positions of which correspond to the screw holes on the supporting I-beam 3, so that the pipe seat 4 can be fixed to the supporting I-beam 3. The protruding part of the pipe seat 4 has screw holes, the positions of which correspond to the screw holes on the pipe clamp 15. The pipe seat 4 and the pipe clamp are bolted together to fix the socket-type pipeline 12.

[0020] The assembled socket-type pipeline 12 (i.e., pipeline module) is placed on the pipe seat 4. One end of the socket-type pipeline 12 is a spigot 20, and the other end is a socket 21, with the outer diameter of the spigot 20 matching the inner diameter of the socket 21. The spigot 20 of one section of socket-type pipeline 12 is inserted into the socket 21 of another section of socket-type pipeline 12, and a rubber ring 18 is provided between the spigot 20 and the socket 21. The assembled socket-type pipeline 12 is placed on the pipe seat 4 and fixed to the pipe seat 4 with pipe clamps 15 and bolts, thereby securing the socket-type pipeline 12.

[0021] The loading module includes a manual pump 13, a hydraulic jack 8, a reaction frame 5, an upper connecting plate 6, a lower connecting plate 7, a loading plate 10, a loading I-beam 11, and a sector-shaped steel plate 24. The manual pump 13 is connected to the hydraulic jack 8 via an oil pipe 14.

[0022] The base of the hydraulic jack 8 is welded to the lower connecting plate 7, which is bolted to the upper connecting plate 6 and fixed to the reaction frame 5. A load cell 9 is welded to the top of the hydraulic jack 8, and a loading plate 10 is welded to the other side of the load cell 9. Four screw holes are provided symmetrically on the loading plate 10.

[0023] Place the loading I-beam 11 onto the socket-type pipeline 12, ensuring that the loading points at both ends are symmetrically positioned on both sides of the socket-type pipeline 12 joint. Fine-tune the extension length of the hydraulic jack 8 so that the loading plate 10 can be bolted and fixed to the loading I-beam 11. Fan-shaped steel plates 24, with radii matching the pipe diameter of the socket-type pipeline 12, are welded symmetrically on both sides of the bottom of the loading I-beam. The detection module includes a load cell 9, an angle sensor 17, a mounting plate 16, a strain gauge 19, and a strain meter 22. The load cell 9 is welded between the hydraulic jack 8 and the loading plate 10, and is connected to the strain meter 22 to detect each level of loading pressure. It can also be used to calculate the bending moment of the joint section.

[0024] Angle sensor 17 can be bolted to mounting plate 16, and mounting plate 16 and angle sensor 17 are arranged above the pipe body at symmetrical positions on both sides of the socket-type pipeline joint 12 via screw holes 23 and bolts. By connecting angle sensor 17 to a computer, the rotation angle at the joint during the test can be obtained.

[0025] Strain gauges 19 are arranged on the outside of the spigot 20 and the inside of the socket 21 of the socket-type pipeline 12. Strain gauges 19 are attached to the inside of the socket 21 and the outside of the spigot 20 of the socket-type pipeline 12 at 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° angles, starting from the top of the pipe and circumferentially. After the spigot 20 is inserted into the socket 21, the attachment positions of the strain gauges 19 on the socket 21 and the spigot 20 must be maintained on the same longitudinal section. The strain gauges 19 are connected to a strain gauge 22 to measure the bending moment at the joint section.

[0026] A loading method for testing the attenuation law of bending stiffness of socket-type pipeline joints, the method comprising the following steps: (1) Determine the positions of the four supports 2 and the height of the supporting I-beam 3 according to the dimensions of the test pipeline, and fix the supporting I-beam 3 to the supports 2 with bolts.

[0027] (2) Arrange strain gauges 19 on the outside of the spigot 20 and the inside of the socket 21 of the socket-type pipeline 12, and attach strain gauges 19 at 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° from the top of the pipe to the inside of the socket 21 and the outside of the spigot 20. After the spigot 20 is inserted into the socket 21, the attachment positions of the strain gauges 19 on the socket 21 and the spigot 20 must be kept on the same longitudinal section. Connect the pipeline, install a rubber ring 18 on the outside of the spigot of one pipeline section, and insert it into the socket 21 of the other pipeline section.

[0028] (3) Fix the pipe seat 4 of the pipeline clamp to the supporting I-beam 3, place the connected pipeline on the pipe seat 4, and connect the pipe seat 4 to the pipe clamp 15 with bolts to fix the pipeline. Place the loading I-beam 11 on the pipeline and bolt it to the loading plate 10 above it. Then bolt the angle sensor 17 to the mounting plate 16, and attach the mounting plate 16 to the pipe body at opposite positions on both sides of the socket-type pipeline 12 joint, and position it directly above the pipe body. Connect the strain gauge, the weighing sensor 9 to the strain meter, and connect the strain meter to the computer to obtain the strain and loading pressure.

[0029] (4) Press the manual pump 13 and apply staged loading. Record the pressure, rotation angle, and strain values ​​after each pressure stage stabilizes until the pipeline joint is completely destroyed. Plot the bending moment versus rotation angle curve at the socket-type pipeline joint to determine the critical bending moment value. .

[0030] (5) Take a socket-type pipe 12 and a rubber ring 18 of the same material and size, and repeat steps (1) to (3). Perform graded loading, controlling the maximum bending moment value to be within 0.2. Record the pressure, rotation angle, and strain at each pressure level. Then, remove the pressure and repeat the graded loading process multiple times. Finally, plot the curves between the bending moment and rotation angle of the socket-type pipeline 12 joint under cyclic loading.

[0031] (6) Adjust the maximum loading bending moment to 0.4. 0.6 0.8 Repeat step (5). This allows us to study the attenuation law of the bending stiffness of the socket-type pipeline 12 joint.

[0032] The above specific embodiments are used to explain and illustrate the present invention, and are only preferred embodiments of the present invention, not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A test method for a test device to determine the attenuation law of bending stiffness of socket-type pipeline joints, characterized in that: The testing device includes: a fixing module, a loading module, a pipeline module, and a detection module; The fixing module includes a base, four supports on the base, two supporting I-beams between the supports, and a pipeline clamp on the supporting I-beams, wherein the pipeline clamp holds a socket-type pipeline. The loading module includes a manual hydraulic control device, a reaction frame, an upper connecting plate, a lower connecting plate, a loading plate, and a loading I-beam. The manual hydraulic control device includes a hydraulic jack and a manual pump, with the manual pump connected to the hydraulic jack via an oil pipe. The reaction frame is mounted on the base of the fixed module, with a lower connecting plate in the center for fixing the hydraulic jack base. The lower connecting plate and the upper connecting plate are fixed to the reaction frame. The lower head of the hydraulic jack is provided with a weighing sensor, a loading plate, and a loading I-beam from top to bottom. The two ends of the loading I-beam are mounted on the socket-type pipeline, and the contact loading points between the two ends of the loading I-beam and the socket-type pipeline are symmetrically arranged on both sides of the joint of the socket-type pipeline. The pipeline module includes two pipeline sections, one end of which is a socket and the other end of which is a spigot. The socket of one pipeline section is matched with the spigot of the other pipeline section, and a rubber ring is installed between the spigot and the matched socket. The detection module includes a load cell, an angle sensor, a strain gauge, and a strain meter. The strain gauge is disposed on the outside of the socket and the inside of the spigot at the joint of the two pipeline sections. The load cell is welded between the hydraulic jack and the loading plate. The strain gauge and the load cell are respectively connected to the strain meter. A pair of angle sensors are symmetrically arranged on the outer surface of the pipeline on both sides of the joint. The testing method includes the following steps: S1. Determine the positions of the four supports and the height of the supporting I-beams according to the dimensions of the socket-type pipeline used in the test, and fix the supporting I-beams to the supports with bolts; S2. Place strain gauges on the outside of the spigot and the inside of the socket of the spigot-and-socket joint. Also, attach strain gauges at 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° from the top of the pipe on the inside of the socket and the outside of the spigot. After the spigot is inserted into the socket, the strain gauges on the socket and spigot must be placed on the same longitudinal section. To connect the pipelines, install a rubber ring on the outside of the spigot of one pipeline section and insert it into the socket of the other pipeline section. S3. Fix the pipe seat of the pipeline clamp to the supporting I-beam, place the connected pipeline on the pipe seat, and connect the pipe seat to the pipe clamp with bolts to fix the pipeline. Place the loading I-beam on the pipeline and bolt it to the loading plate above it; Then, the angle sensor is bolted to the mounting plate, and the mounting plate is pasted onto the pipe body at opposite positions on both sides of the socket-type pipe joint, directly above the pipe body; The strain gauge, load cell, and strain meter are connected together, and the strain meter is connected to a computer to obtain the strain and the applied pressure. S4. Press the manual pump and use staged loading. Record the rotation angle and strain value after each pressure stabilizes until the pipeline joint is completely destroyed. Plot the bending moment versus rotation curve at the socket-type pipe joint to determine the critical bending moment value. ; S5. Take socket-type pipelines and rubber rings of the same material and size, and repeat steps S1 to S3. Staged loading was applied, with the maximum bending moment controlled at 0.

2. Record the rotation angle and strain under each pressure level, then remove the pressure, repeat the graded loading step multiple times, and finally plot the curve between the bending moment and rotation angle of the socket pipe joint under cyclic loading. S6. Take socket-type pipelines and rubber rings of the same material and size, and repeat steps S1 to S3. Staged loading was applied, with the maximum bending moment controlled at 0.

4. Record the rotation angle and strain under each pressure level, then remove the pressure, repeat the graded loading step multiple times, and finally plot the curve between the bending moment and rotation angle of the socket pipe joint under cyclic loading. S7. Take socket-type pipelines and rubber rings of the same material and size, and repeat steps S1 to S3. Staged loading was applied, with the maximum bending moment controlled at 0.

6. Record the rotation angle and strain under each pressure level, then remove the pressure, repeat the graded loading step multiple times, and finally plot the curve between the bending moment and rotation angle of the socket pipe joint under cyclic loading. S8. Take socket-type pipelines and rubber rings of the same material and size, and repeat steps S1 to S3. Staged loading was applied, with the maximum bending moment controlled at 0.

8. Record the rotation angle and strain under each pressure level, then remove the pressure, repeat the graded loading step multiple times, and finally plot the curve between the bending moment and rotation angle of the socket pipe joint under cyclic loading. This study investigates the attenuation law of the bending stiffness of socket-type pipeline joints.

2. The test method according to claim 1, characterized in that: The support has multiple rows of screw holes vertically from top to bottom to adjust the distance between the supporting I-beam and the base as needed for the test.

3. The test method according to claim 1, characterized in that: Two fan-shaped steel plates are welded to both ends of the bottom of the loading I-beam, and the fan-shaped diameter of the steel plates is adapted to the outer diameter of the socket-type pipeline.

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