A simulation test device for buried pipelines

Abstract

The present invention provides a simulation test device for buried pipelines, which relates to the field of pipeline testing. The simulation test device for buried pipelines includes a base, a test box, a vertical loading mechanism and a boundary loading mechanism. The test box is installed on the base, and the vertical loading mechanism is installed at the lower part of the test box to simulate the local settlement of soil. The test box includes end plates, with movable holes formed in the end plates, and retaining plates corresponding to the movable holes are slidably installed on the end plates. A force transmission member penetrates through the retaining plates, and one end of the force transmission member is used for connecting with the test pipeline. The boundary loading mechanism includes a lifting structure and a stretching driving structure. The lifting structure is fixed on the base, the stretching driving structure is installed on the lifting structure, and the stretching driving structure is in transmission connection with the other end of the force transmission member. An axial tensile force is generated on the end of the test pipeline through the stretching driving structure, truly simulating the non-linear constraint effect of the straight section of the buried pipeline on the bending section, and the stress state of the pipeline in the uneven settlement area.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline testing, and particularly to a simulation test device for buried pipelines. Background Art

[0002] Underground pipelines are known as the "lifelines of cities" and are responsible for functions such as water supply and drainage, gas transmission and heating, and power communication. In areas prone to geological disasters, uneven settlement of the ground will affect the safety of buried pipelines, and it is necessary to conduct experimental evaluations on the stress states of buried pipelines.

[0003] In practice, the straight-line distance of buried pipeline laying is very long. Under the action of uneven formation settlement, according to the position of the anchor points, the stress states of buried pipelines are divided into an anchored section (without stress) and a non-anchored section (with stress). The non-anchored section can be further divided into a straight section far from the formation mutation and a bent section near the formation mutation.

[0004] Currently, common buried pipeline tests are mainly completed using indoor model box tests. For example, the Chinese invention patent application with the application publication number CN105203387A and the application publication date of December 30, 2015, discloses a pipe-soil simulation test device under site settlement and fault effects, and specifically discloses that the test device includes a fixed box body, a vertically moving box body, and a horizontally moving box body arranged in sequence. The soil in the three box bodies is an integrally combined whole, and the test pipeline passes through the three box bodies; the fixed box body is welded or anchored on a fixed platform, the vertically moving box body is placed on a temporary support frame and removed before the test starts; the horizontally moving box body is placed on a limit track through pulley assemblies installed at its bottom; the loading part includes an MTS power device, a vertical loading jack, and a horizontal loading jack. By using the MTS power device to control the settlement displacement of the moving box body, and by adjusting the pressure of the vertical loading jack, the stress effects of different burial depths on the pipeline can be simulated.

[0005] However, the length of the test pipeline in the existing simulation test device is much smaller than the actual pipeline length. If the test pipeline is anchored in the fixed box body, a fixed boundary is formed at its end, which magnifies the axial force of the pipeline and weakens the bending moment during the stress test, and cannot truly simulate the constraint effect of the straight section of the buried pipeline on the bent section; if no constraint measures are taken at both ends of the test pipeline, a free boundary is formed at its end, resulting in the pipeline settling together with the subsiding soil during the test, magnifying the bending moment of the pipeline and weakening the axial force.

[0006] In summary, whether it is a fixed boundary or a free boundary in the existing test device, neither can truly and equivalently simulate the straight section part of the pipeline stress state, and there are significant differences from the pipeline end conditions in the actual working conditions, and the stress state of the pipeline in the uneven settlement area cannot be accurately tested. Summary of the Invention

[0007] To solve the above problems, the object of the present invention is to provide a simulation test device for buried pipelines, so as to solve the problems that the constraint effect of the straight section of the buried pipeline on the bent section cannot be truly simulated, and the stress state of the pipeline under uneven settlement areas cannot be accurately tested.

[0008] The technical solution of the simulation test device for buried pipelines of the present invention is as follows:

[0009] The simulation test device for buried pipelines includes a base, a test box, a vertical loading mechanism, and a boundary loading mechanism. The test box is installed on the base, and the vertical loading mechanism is installed at the lower part of the test box to simulate the local settlement of the soil body;

[0010] The test box includes end plates. Activity holes are formed in the end plates. Retaining plates corresponding to the activity holes are slidably installed on the end plates. A force transmission member penetrates through the retaining plates. One end of the force transmission member is used to connect with the test pipeline inside the box;

[0011] The boundary loading mechanism includes a lifting structure and a stretching driving structure. The lifting structure is fixed on the base, the stretching driving structure is installed on the lifting structure, and the stretching driving structure is in transmission connection with the other end of the force transmission member.

[0012] Further, the base includes a bottom plate and an outer stand. The test box and the vertical loading mechanism are respectively installed on the bottom plate. The outer stand is fixedly arranged outside the boundary loading mechanism. The end of the stretching driving structure far from the force transmission member is slidably assembled on the outer stand.

[0013] Further, the stretching driving structure is an electro-hydraulic servo actuator, and a load sensor is connected between the electro-hydraulic servo actuator and the force transmission member.

[0014] Further, the electro-hydraulic servo actuator includes an actuator body with an internal displacement sensor, a servo valve, a first hinge, and a second hinge. The servo valve is arranged on the actuator body with the internal displacement sensor. The first hinge is connected between the actuator body with the internal displacement sensor and the force transmission member. The second hinge is arranged at the end of the actuator body with the internal displacement sensor close to the outer stand.

[0015] Further, a vertical track is arranged inside the outer stand. The cross-sectional shape of the vertical track is T-shaped. A slider is slidably assembled in the vertical track. The electro-hydraulic servo actuator is connected with the slider, and the slider is in stop cooperation with the outer edge of the vertical track.

[0016] Further, a fixed support is provided on the bottom plate, the test box is fixedly arranged on the fixed support, and the test box has an opening part extending outside the fixed support;

[0017] The vertical loading mechanism is arranged on the lower side of the opening part. The vertical loading mechanism includes a settlement plate and a vertical loading member. The settlement plate is in concave-convex fit with the opening part, and the vertical loading member is arranged on the bottom plate and is in transmission connection with the settlement plate.

[0018] Further, the force transmission member is a force transmission rod, and a vertical displacement sensor for detecting the displacement of the force transmission rod is further arranged outside the end plate. A through hole is formed in the retaining plate, and the force transmission rod is arranged in the through hole in a direction perpendicular to the plate surface of the retaining plate.

[0019] Further, a flange bearing is arranged at the perforation of the retaining plate, and the force transmission rod is installed in the inner hole of the flange bearing.

[0020] Further, the shape of the test box is rectangular parallelepiped. The test box includes two side plates arranged in parallel at intervals with respect to the test pipeline. An observation window is arranged in the middle of the front side plate of the test box, and a foam layer is lined on the inner wall of the test box.

[0021] Further, there are two boundary loading mechanisms, which are respectively a first boundary loading mechanism and a second boundary loading mechanism, and the structures of the first boundary loading mechanism and the second boundary loading mechanism are the same;

[0022] The shape of the test box is rectangular parallelepiped. The test box includes two end plates arranged opposite to each other. The first boundary loading mechanism is arranged outside one of the end plates, and the second boundary loading mechanism is arranged outside the other end plate.

[0023] Beneficial effects: The simulation test device for the buried pipeline adopts the structural design of a base, a test box, a vertical loading mechanism and a boundary loading mechanism. Among them, the vertical loading mechanism can simulate the local settlement of the soil body. The boundary loading mechanism includes a lifting structure and a stretching driving structure. The stretching driving structure is connected to the test pipeline in the box through a force transmission member. Through the lifting structure, the binding force on the end of the test pipeline during the test process always acts in the axial direction of the pipeline. Through the stretching driving structure, an axial tensile force is generated on the end of the test pipeline, so that the stress and deformation of the test pipeline in the test box are closer to the stress and deformation of the buried pipeline in the actual situation. It can truly simulate the non-linear constraint effect of the straight section of the buried pipeline on the bending section, and accurately test the stress state of the pipeline in the uneven settlement area.

[0024] Moreover, an activity hole is formed in the end plate of the test chamber, and a retaining plate corresponding to the activity hole is slidably mounted on the end plate. A force transmission member penetrates through the retaining plate, and the restraint effect of the boundary loading mechanism is transmitted to the test pipeline through the force transmission member. The retaining plate plays a role in shielding the soil in the chamber, preventing the soil layer from scattering outward during the test, and making the entire simulation test more real and accurate.

[0025] Finally, the up-and-down sliding design of the boundary loading mechanism and the cross-shaped hole layout of the force transmission rod can meet the test requirements for different pipeline burial depths and different pipe diameters; an observation window is provided in the middle of the front side plate of the test chamber. Combining with the particle image velocimetry technology, the development trajectory and distribution range of the soil shear band can be determined. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the buried pipeline simulation test device in a specific embodiment of the buried pipeline simulation test device of the present invention;

[0027] Figure 2 is Figure 1 an enlarged schematic diagram of the tensile drive structure in;

[0028] Figure 3 is a front view schematic diagram of the buried pipeline simulation test device (excluding the lifting structure) in a specific embodiment of the buried pipeline simulation test device of the present invention;

[0029] Figure 4 is a top view schematic diagram of the buried pipeline simulation test device in a specific embodiment of the buried pipeline simulation test device of the present invention;

[0030] Figure 5 is a right view schematic diagram of the buried pipeline simulation test device in a specific embodiment of the buried pipeline simulation test device of the present invention;

[0031] Figure 6 is a schematic diagram of the boundary loading force - time of the buried pipeline simulation test device in a specific embodiment of the buried pipeline simulation test device of the present invention.

[0032] In the figure: 1 - base, 10 - bottom plate, 11 - outer vertical frame, 12 - fixed support;

[0033] 2 - test chamber, 21 - end plate, 22 - retaining plate, 23 - side plate, 24 - observation window, 25 - foam layer, 26 - flange bearing, 27 - vertical displacement sensor;

[0034] 3 - vertical loading mechanism, 30 - settlement plate, 4 - electro-hydraulic servo actuator, 40 - actuator body with built-in displacement sensor, 41 - force transmission member, 42 - load sensor, 43 - servo valve, 44 - slider, 45 - first hinge, 46 - second hinge, 5 - lifting structure, 6 - test pipeline. Detailed implementation manners

[0035] The following will further describe in detail the specific implementation manners of the present invention in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0036] Specific embodiment 1 of the simulation test device for buried pipelines of the present invention is as Figures 1 to 6 shown. The simulation test device for buried pipelines includes a base 1, a test box 2, a vertical loading mechanism 3 and a boundary loading mechanism. The test box 2 is installed on the base 1, and the vertical loading mechanism 3 is installed at the lower part of the test box 2 to simulate the local settlement of the soil mass; the test box 2 includes an end plate 21, an activity hole is opened on the end plate 21, and a retaining plate 22 corresponding to the activity hole is slidably installed on the end plate 21. A force transmission member 41 penetrates through the retaining plate 22, and one end of the force transmission member 41 is used to connect with the test pipeline 6 in the box; the boundary loading mechanism includes a lifting structure 5 and a stretching driving structure. The lifting structure 5 is fixed on the base 1, the stretching driving structure is installed on the lifting structure 5, and the stretching driving structure is in transmission connection with the other end of the force transmission member 41.

[0037] The simulation test device for buried pipelines adopts the structural design of the base 1, the test box 2, the vertical loading mechanism 3 and the boundary loading mechanism. Among them, the vertical loading mechanism 3 can simulate the local settlement of the soil mass. The boundary loading mechanism includes a lifting structure 5 and a stretching driving structure. The stretching driving structure is connected with the test pipeline 6 in the box through the force transmission member 41. By means of the lifting structure 5, the binding force on the end of the test pipeline 6 during the test process always acts in the axial direction of the pipeline. An axial tensile force acts on the end of the test pipeline 6 through the stretching driving structure, so that the stress and deformation of the test pipeline 6 in the test box 5 are closer to the stress and deformation of the buried pipeline in the actual situation, and the non-linear constraint effect of the straight section of the buried pipeline on the bending section can be truly simulated, and the stress state of the pipeline in the uneven settlement area can be accurately tested. Moreover, an activity hole is opened on the end plate 21, a retaining plate 22 corresponding to the activity hole is slidably installed on the end plate 21, and a force transmission member 41 penetrates through the retaining plate 22. The constraint effect of the boundary loading mechanism is transmitted to the test pipeline 6 through the force transmission member 41, and the retaining plate 22 plays a role in shielding the soil mass in the box to prevent the soil layer from scattering outwards during the test process, making the whole simulation test more real and accurate.

[0038] In this embodiment, the base 1 includes a bottom plate 10 and an external frame 11, the test box 2 and the vertical loading mechanism 3 are respectively installed on the bottom plate 10, the external frame 11 is fixedly arranged on the outside of the boundary loading mechanism, and the end of the tensile drive structure 4 away from the force transmission member 41 is slidably assembled on the external frame 11. The test box 2 and the vertical loading mechanism 3 are installed on the bottom plate 10 to ensure the stability of the test box 2 during the test. The external frame 11 and the bottom plate 10 are fixed by welding. The external frame 11 fixed to the bottom plate 10 plays a role of sliding up and down guiding the end of the tensile drive structure 4 away from the force transmission member 41, ensuring the accuracy of the up and down movement of the tensile drive structure 4.

[0039] A vertical track is provided inside the external frame 11, and the cross-sectional shape of the vertical track of the external frame 11 is T-shaped. A slider 44 is slidably mounted in the vertical track, and the electro-hydraulic servo actuator 4 is connected to the slider 44, and the slider 44 is matched with the outer edge of the vertical track of the external frame 11. The cross-sectional shape of the vertical track of the external frame 11 is designed to be T-shaped, and the outer edge of the vertical track is matched with the slider to ensure the accurate output of the boundary constraint force, thereby improving the lateral support of the tensile drive structure 4.

[0040] Specifically, the stretching drive structure is an electro-hydraulic servo actuator 4, and a load sensor 42 is connected between the electro-hydraulic servo actuator 4 and the force transmission member 41. The electro-hydraulic servo actuator 4 includes an actuator body 40 with a built-in displacement sensor, a servo valve 43, a first hinge 45, and a second hinge 46. The servo valve 43 is arranged on the actuator body 40 with a built-in displacement sensor, the first hinge 45 is connected between the actuator body 40 with a built-in displacement sensor and the force transmission member 41, and the second hinge 46 is arranged at the end of the actuator body 40 with a built-in displacement sensor close to the external frame 11. The actuator body 40 with a built-in displacement sensor converts hydraulic energy into mechanical energy, and the speed, direction, and displacement of the output load are more accurate.

[0041] The electro-hydraulic servo actuator 4 is externally connected to a control system, and commands are issued by a boundary load force-time relationship program embedded in a computer, such as Figure 6 As shown, the control accurately inputs the end restraint force to the test pipe 6, effectively simulating the nonlinear restraint effect of the straight section of the pipeline on the curved section of the pipeline at the sudden change of the distant formation in the actual working condition.

[0042] A fixed support 12 is provided on the bottom plate 10, and the test box 2 is fixedly set on the fixed support 12. The test box 2 has an opening part cantilevered to the outside of the fixed support 12; the vertical loading mechanism 3 is arranged on the lower side of the opening part of the test box 2, and the vertical loading mechanism 3 includes a settlement plate 30 and a vertical loading member. The settlement plate 30 is concave-convexly matched with the opening part, and the vertical loading member is set on the bottom plate 10 and is transmission-connected to the settlement plate 30.

[0043] Specifically, there are four vertical loaders, which are fixed to the lower side of the settlement plate 30 by screws respectively. The vertical loaders are equipped with displacement sensors and load sensors, and are externally connected to a control system to ensure that the four vertical loaders synchronously lower the settlement plate 30 step by step to achieve the purpose of simulating uneven settlement of the soil layer.

[0044] The force transmission member 41 is a force transmission rod. A vertical displacement sensor 27 for detecting the displacement of the force transmission rod is also provided on the outer side of the end plate 22. A through hole is provided on the retaining plate 22. The force transmission rod is inserted into the through hole perpendicular to the plate surface of the retaining plate 22. The vertical displacement sensor 27 is used to detect the vertical displacement of the force transmission rod and the end of the test pipe 6. A flange bearing 26 is provided at the through hole of the retaining plate 22. The force transmission rod is installed in the inner hole of the flange bearing 26. In addition, a rectangular cavity is provided in the end plate 22. The retaining plate 22 is slidably installed in the rectangular cavity. Lubricating oil is applied to the rectangular cavity and the vertical track of the external frame 11 to reduce sliding friction.

[0045] The test box 2 is in the shape of a rectangular parallelepiped, and includes two side panels 23 arranged parallel to the test pipe at intervals, an observation window 24 is provided in the middle of the front side panel of the test box 2, and a foam layer 25 is provided on the inner wall of the test box 2. The foam layer 25 can eliminate the friction between the soil and the inner wall of the box, and realize the simulation of the infinitely far soil; and the foam layer 25 ensures that the settling plate 30 can move downward smoothly, and prevents soil particles from sliding outward from the gap between the settling plate 30 and the inner wall of the test box 2.

[0046] Among them, there are two boundary loading mechanisms 4, which are the first boundary loading mechanism and the second boundary loading mechanism, and the structures of the first boundary loading mechanism and the second boundary loading mechanism are the same; the test box 2 is in the shape of a rectangular parallelepiped, and the test box 2 includes two end plates 21 arranged oppositely, the first boundary loading mechanism is arranged on the outside of one end plate, and the second boundary loading mechanism is arranged on the outside of the other end plate.

[0047] Before the test, the test box 2 is filled with soil in layers and compacted, and a test pipe 6 is arranged along the length direction of the test box 2. Strain gauges, distributed optical fiber measuring elements, etc. are pre-attached on the pipe according to the test purpose. The end of the test pipe 6 is connected to the cross-shaped hole of the force transmission rod, and the connection and assembly of the test pipe 6 and the force transmission rod are achieved by bolts and screws. The up and down sliding design of the boundary loading mechanism and the cross-shaped hole arrangement of the force transmission rod can meet the test requirements of different pipeline burial depths and different pipe diameters; the vertical displacement sensor 27 is installed on the outside of the end plate 21, and the force transmission rod is supported by a pin and a certain compression amount is set, and the soil is continued to be filled in layers and compacted until the test requirements are met.

[0048] According to the test plan, the test is started. Instructions are sent by the embedded program of the computer, and the four vertical loading members of the vertical loading mechanism 3 are started through the control system to synchronously and coordinately lower the settlement plate 30 step by step, simulating the uneven settlement of the formation in the real working condition. While the formation is settling, instructions are sent by the boundary loading force-time relationship program embedded in the computer, so that during the test, under the action of the binding force, internal force response and deformation results are generated in the test pipe 6, realizing the non-linear constraint effect of the straight section of the pipe on the bent section of the pipe at the far formation mutation in the actual working condition. The displacement sensor hole built in the electro-hydraulic servo actuator 4 can monitor the axial displacement of the end of the test pipe 6. Combining with the applied binding force, the tensile strength of the test pipe 6 is further analyzed. At the same time, according to the vertical displacement sensor 27 monitoring the vertical displacement of the end of the test pipe 6, instructions are sent by the embedded program of the computer, and the automatic lifting of the lifting structure 5 is controlled through the control system to ensure that the position of the electro-hydraulic servo actuator 4 is always on the same horizontal line as the end of the test pipe 6 during the test, realizing that the binding force on the end of the test pipe 6 always acts in the direction of the pipe axis. The development trajectory of the soil shear band is automatically and continuously captured by a camera through the observation window 24.

[0049] After the test is completed, based on the data collected by the data acquisition device, the force and deformation analysis of the test pipe 6 is carried out to obtain a more accurate force state of the test pipe 6. Combining with the particle image velocimetry technology, the distribution range of the soil shear band is determined to further reveal the failure mechanism of the buried pipeline and provide design parameters for the buried pipeline in the ground uneven settlement area that are economical and reasonable.

[0050] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can still be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. A simulation test device for buried pipelines, Characterized in that, It includes a base, a test box, a vertical loading mechanism and a boundary loading mechanism. The test box is installed on the base, and the vertical loading mechanism is installed at the lower part of the test box to simulate the local subsidence of the soil body; The test box includes end plates. Activity holes are opened on the end plates. Retaining plates corresponding to the activity holes are slidably installed on the end plates. A force transmission member penetrates through the retaining plates. One end of the force transmission member is used to connect with the test pipeline inside the box; The boundary loading mechanism includes a lifting structure and a stretching driving structure. The lifting structure is fixed on the base, the stretching driving structure is installed on the lifting structure, and the stretching driving structure is in transmission connection with the other end of the force transmission member; The base includes a bottom plate and an outer stand. The test box and the vertical loading mechanism are respectively installed on the bottom plate. The outer stand is fixedly arranged outside the boundary loading mechanism. The end of the stretching driving structure far from the force transmission member is slidably assembled up and down on the outer stand; The stretching driving structure is an electro-hydraulic servo actuator. A load sensor is connected between the electro-hydraulic servo actuator and the force transmission member; Vertical tracks are arranged inside the outer stand. The cross-sectional shape of the vertical tracks is T-shaped. Sliders are slidably assembled in the vertical tracks. The electro-hydraulic servo actuator is connected with the sliders. The sliders are in stop cooperation with the outer edges of the vertical tracks; The electro-hydraulic servo actuator includes an actuator body with an built-in displacement sensor, a servo valve, a first hinge and a second hinge. The servo valve is arranged on the actuator body with the built-in displacement sensor. The first hinge is connected between the actuator body with the built-in displacement sensor and the force transmission member. The second hinge is arranged at the end of the actuator body with the built-in displacement sensor close to the outer stand.

2. The simulation test device for buried pipelines according to claim 1, Characterized in that, Fixed supports are arranged on the bottom plate. The test box is fixedly arranged on the fixed supports. The test box has an opening part extending outside the fixed supports; The vertical loading mechanism is arranged on the lower side of the opening part. The vertical loading mechanism includes a settlement plate and a vertical loading member. The settlement plate is in concave-convex fit with the opening part. The vertical loading member is arranged on the bottom plate and is in transmission connection with the settlement plate.

3. The simulation test device for buried pipelines according to claim 1, Characterized in that, The force transmission member is a force transmission rod. A vertical displacement sensor for detecting the displacement amount of the force transmission rod is further arranged outside the end plate. Through holes are opened on the retaining plates. The force transmission rod is arranged in the through holes in the direction perpendicular to the plate surface of the retaining plates.

4. The simulation test device for buried pipelines according to claim 3, Characterized in that, Flange bearings are arranged at the perforation parts of the retaining plates. The force transmission rod is installed in the inner holes of the flange bearings.

5. The simulation test device for buried pipelines according to claim 1, Characterized in that, The test chamber is in the shape of a cuboid. The test chamber includes two side plates arranged at intervals parallel to the test pipeline. A viewing window is provided in the middle of the front side plate of the test chamber. The inner wall of the test chamber is lined with a foam layer.

6. The simulation test device for buried pipelines according to claim 1, characterized in that, There are two boundary loading mechanisms, namely the first boundary loading mechanism and the second boundary loading mechanism respectively, and the structures of the first boundary loading mechanism and the second boundary loading mechanism are the same; The test chamber is in the shape of a cuboid. The test chamber includes two end plates arranged opposite to each other. The first boundary loading mechanism is arranged outside one of the end plates, and the second boundary loading mechanism is arranged outside the other end plate.

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