Simulation device and method for inducing extravascular edema from pipe defect development

Abstract

This invention relates to the field of buried pipeline testing technology, and discloses a simulation device and method for simulating the inward seepage of external water induced by pipeline defect development. The simulation device continuously and precisely controls the rotation angle, pulling stroke, or lifting displacement of the pipe segments / pipeline body, thereby completely reproducing the gradual development process of defects in a single test. For example, axial cracks can first form an initial crack through slight rotation of the middle layer of the pipe segment, then simulate the rapid axial extension process by pulling the inner and outer layers of the pipe segment, and finally simulate the opening and expansion of the crack through continuous rotation; misalignment defects can be simulated by controlling the gradual descent of the base plate, simulating the continuous displacement process of the joint from slight misalignment to severe misalignment. This makes the simulated defects close to actual defects in morphology, location, and mechanical boundary conditions, thus enabling the experimental data to accurately correspond to the time series and grade evolution of defect development, providing technical support for revealing the dynamic response law between inward seepage of external water and defect development.

Description

Technical Field

[0001] This invention relates to the field of buried pipeline testing technology, specifically to a simulation device and method for induced infiltration of external water by pipeline defect development. Background Technology

[0002] Improving the quality and efficiency of urban sewage pipe networks is one of the core tasks of urban water environment management in my country. Pipe defects (such as ruptures, misalignments, and disconnections) leading to the infiltration of external water from high groundwater levels are a key cause of low influent concentrations, inflated operating loads, and increased energy consumption at sewage treatment plants. Accurately understanding the patterns of external water infiltration under different defect types and development levels is a crucial prerequisite for scientifically diagnosing pipe network malfunctions and developing economical and efficient repair strategies.

[0003] Currently, physical model testing is the primary technical method for studying the leakage patterns of defective pipelines. Most existing testing devices simulate leaks by pre-fabricating pipes with notches, for example, by creating a fixed-size notch in the pipe before burying it, sealing it, and then opening the notch during the test to measure the leakage. In recent years, some studies have proposed a combined inner pipe and sleeve structure, where rotating the sleeve exposes different pre-set leakage points on the inner pipe, increasing the diversity of leakage point simulation. All these schemes employ a simulation approach of "pre-set notches and discrete switching."

[0004] However, in reality, pipe ruptures often begin with tiny, invisible cracks. Under the continuous action of factors such as load and corrosion, these cracks gradually extend and widen. Similarly, misalignment and dislocation also develop from slight displacement and loosening into severe misalignment and separation. In actual use, the artificially pre-designed, fixed-size holes in existing devices are severely inconsistent with the morphology of these extended and expanding cracks or joint displacement defects. Furthermore, it is impossible to continuously and accurately control the dimensional changes of defects during experiments to simulate their entire development process. This makes it difficult for existing model tests to obtain leakage data throughout the entire process of defect initiation, development, and final formation, thus hindering in-depth research on the development of pipe defects and the dynamic evolution of external water seepage. Summary of the Invention

[0005] This invention provides a simulation device for the infiltration of external water induced by the development of pipeline defects. It aims to solve the technical problem that existing pipeline leakage simulation test devices can only simulate static pipeline gaps of preset size, and cannot truly reflect the dynamic evolution of pipeline defects such as rupture, misalignment, and disconnection from their inception to expansion, thus making it difficult to obtain the laws of infiltration of external water at each stage of defect development.

[0006] In a first aspect, the present invention provides a simulation device for inducing external water seepage due to pipeline defect development, comprising a test soil box, a test pipeline, and a driving mechanism. The test pipeline is buried in the soil within the test soil box, and includes a pipeline body and at least one set of defect simulation structures disposed on the pipeline body. Each defect simulation structure includes at least one movable segment, forming a pipeline defect between the movable segment and the pipeline body. The driving mechanism is connected to the movable segment and is used to drive the movable segment to move continuously relative to the pipeline body, thereby changing the geometric characteristic parameters of the pipeline defect.

[0007] Beneficial effects: By setting up movable segments independently controlled by a drive mechanism, the rotation angle and extension stroke of the segments can be continuously and precisely controlled, thereby reproducing the gradual development process of defects in a single experiment. For example, axial cracks can first form an initial crack through slight rotation of the segments, then simulate axial extension by extending the segments, and finally simulate crack opening and expansion through continuous rotation; misalignment defects can be simulated by controlling the gradual descent of the base plate, simulating the continuous displacement process of the joint from slight misalignment to severe misalignment. This makes the simulated defects close to actual defects in morphology, location, and mechanical boundary conditions, thus enabling the experimental data to accurately correspond to the time series and grade evolution of defect development, providing technical support for revealing the dynamic response law between external water infiltration and defect development.

[0008] In one optional embodiment, the defect simulation structure includes an axial crack simulation structure, which includes at least one rotatable assembled pipe segment group. The assembled pipe segment group consists of at least two circumferentially assembled pipe segments, and the joint between the two assembled pipe segments extends along the pipe axis or extends at a certain angle to the pipe axis.

[0009] Beneficial Effects: By setting up at least two circumferentially joined segments with their joints along the axial direction or at any angle intersecting the axis, axial and diagonal cracks can be simulated. Furthermore, by replacing segments with different angles, various diagonal crack conditions can be simulated, overcoming the limitation of existing technologies that can only simulate single-direction gaps, making the test results more representative. Simultaneously, variable experiments can be conducted, supporting comparative studies of the impact of crack orientation on external water infiltration, providing experimental methods and key data for establishing direction-dependent leakage prediction models. For example, while keeping crack width and length constant, only the angle between the joint and the axis can be changed to quantitatively study the impact of crack orientation on seepage patterns, leakage volume, and the extent of soil collapse around the pipe. In addition, as independent replaceable modules, the joined segments only require pre-preparation of segments with different joint angles, allowing for rapid switching of test conditions on the same pipeline body without disassembling the entire pipeline, replacing the soil, or refilling. This significantly shortens the preparation time for multi-angle comparative tests and avoids data dispersion caused by soil differences between different test batches, improving the comparability and reliability of test results.

[0010] In one optional embodiment, the axial crack simulation structure further includes a first outer pull-out tube segment and a first inner pull-out tube segment that can move axially, the first outer pull-out tube segment and the first inner pull-out tube segment being respectively disposed on the radially outer side and the radially inner side of the assembled tube segment group.

[0011] Beneficial effects: By setting up an axially movable first outer layer and a first inner layer of pull-out segments, the axial length of the crack can be independently controlled. Combined with the control of the circumferential width of the crack by the assembled segment group, the influence of width and length on the infiltration of external water can be studied separately in the same experiment. This avoids data confusion caused by the coupling of dimensional parameters in the traditional fixed-gap scheme, providing clearer experimental basis for establishing a high-precision leakage prediction model. At the same time, it can also achieve staged and layered control, realistically reproducing the evolution of the crack depth direction, and overcoming the deficiency of existing technologies that can only simulate through cracks. In addition, the multi-layer pull-out structure, compared with the existing technology that requires pre-excavation of soil or overall pipe movement, has a smaller annular gap due to the thinner thickness of each pull-out segment. Therefore, it will not cause significant soil settlement or hole collapse, reducing the interference of human factors on the interaction between soil and pipe during the experiment, and making the measured infiltration more closely resemble the actual working conditions.

[0012] In one optional embodiment, the defect simulation structure includes a circumferential crack simulation structure. The circumferential crack simulation structure includes a second outer layer of pull-out tube segments, a middle layer of rotating tube segments, and a second inner layer of pull-out tube segments arranged radially from the outside to the inside along the pipe wall. The second outer layer of pull-out tube segments and the second inner layer of pull-out tube segments are axially movable to form a gap at the end of the tube segments along the circumferential direction of the pipe. The middle layer of rotating tube segments is rotatably arranged to control the extension length of the circumferential gap.

[0013] Beneficial Effects: By axially moving the second outer and second inner pull-out tube segments, circumferential cracks existing only on the outer and / or inner walls can be formed at the pipe ends, simulating initial surface cracks. Then, through continuous rotation of the middle rotating tube segment, the cracks are made to extend along the wall thickness direction, forming complete circumferential cracks, and the extension length of the circumferential cracks is gradually adjusted. This forms a staged and layered control, accurately simulating the gradual development process of circumferential cracks on the pipe cross-section. Simultaneously, by separately controlling the second outer and second inner pull-out tube segments and the middle rotating tube segment, the effects of crack length (circumferential range) and crack width (axial range) on the amount of external water seepage can be studied in experiments. This provides decoupled experimental data for establishing a multivariate leakage model, overcoming the limitation of traditional preset notches that cannot distinguish these parameters. Furthermore, with the incomplete rotation of the middle rotating tube segment, asymmetric damage morphology where cracks only appear in local circumferential angles of the pipe (e.g., cracking only in the upper half of the circumference) can be simulated, realistically reflecting the complex crack characteristics caused by uneven circumferential constraints or localized corrosion.

[0014] In one optional embodiment, the drive mechanism includes a mounting base, a segment holder, and a rotating assembly. The segment holder is mounted on the mounting base and is used to hold the assembled segment or the rotating middle layer segment; the rotating assembly is used to drive the segment holder to rotate.

[0015] Beneficial effects: By directly clamping the assembled segments or the rotating segments in the middle layer with the segment holder, and with the precise drive of the rotating assembly, the rotation angle error can be controlled within a very small range. The real-time change of the crack width can be quantitatively calculated based on the preset angle, thereby realizing continuous, repeatable and high-precision adjustment of the crack opening degree, providing a reliable basis for obtaining the quantitative relationship between crack width and the amount of infiltration of external water.

[0016] In one optional embodiment, the segment holder is further used to hold the first outer layer pull-out segment, the first inner layer pull-out segment, the second outer layer pull-out segment, or the second inner layer pull-out segment. The driving mechanism further includes a mounting platform, a driver, a moving platform, and a segment clamping connection frame. A slide rail is provided on one side of the mounting platform along its length, and a helical rod push shaft parallel to the slide rail is provided on the other side. The driver is mounted at one end of the mounting platform and is drivenly connected to one end of the helical rod push shaft via a first transmission assembly. One side of the moving platform is slidably connected to the slide rail, and the other side is helically driven connected to the helical rod push shaft. The segment clamping connection frame is mounted above the moving platform, and a segment holder is provided at one end of the segment clamping connection frame. The driver drives the helical rod push shaft to rotate, thereby moving the moving platform and the segment clamping connection frame axially.

[0017] Beneficial effects: By employing a helical drive pair between the screw propulsion shaft and the moving platform, coupled with forward and reverse control of the actuator, rotational motion can be smoothly converted into linear movement of the segment holder. This provides micron-level displacement resolution, and the displacement is strictly linearly related to the actuator's rotation angle, facilitating real-time recording of the pulling stroke. It allows for precise control of each stage of crack length change from initial initiation to full expansion, providing a reliable basis for establishing a quantitative relationship between crack length and external water infiltration. The threaded engagement between the screw propulsion shaft and the moving platform provides a self-locking characteristic, preventing displacement rebound due to soil resistance during pulling, ensuring the crack length parameter remains constant throughout the test, and significantly improving data reliability.

[0018] In one optional embodiment, the test pipeline includes a staggered simulated pipe, and the test soil box is provided with a bottom plate that can move up and down. The staggered simulated pipe is placed above the bottom plate, and the bottom plate is connected to a lifter for driving the bottom plate to move up and down so that the staggered simulated pipe produces vertical displacement.

[0019] Beneficial Effects: By driving the movable base plate to actively descend via a lifting device, the simulated misaligned pipe placed above it undergoes controllable vertical displacement, while the pipe section constrained by the adjacent fixed connecting pipe remains in place. This creates a realistic vertical misalignment between the two pipes, fully replicating the gradual evolution of the misalignment from minor displacement to severe misalignment. Simultaneously, by correlating the external water seepage volume corresponding to different descent stages, a quantitative relationship between the misalignment displacement and the external water seepage volume can be directly established, providing experimental basis for pipeline defect classification assessment and repair threshold determination. Furthermore, by employing a method of limiting the axial displacement of the fixed pipe and actively settling the simulated pipe, the vertical displacement of the simulated misaligned pipe is slowly completed from bottom to top, driven by the base plate. Its movement direction is consistent with the direction of soil self-weight stress, minimizing lateral compression and disturbance to the surrounding soil. This reduces interference from the experimental operation on the soil-pipe interaction, making the measured seepage data closer to real working conditions and ensuring accurate repeatability of the leakage test process.

[0020] In one optional embodiment, the test pipeline includes at least two pipeline bodies and pipe joints connecting adjacent pipeline bodies. The test soil box is provided with jacking structures on both sides, which are fixedly connected to the two exposed end faces of the pipeline bodies to drive the pipeline bodies to move axially.

[0021] Beneficial effects: By applying jacking force through the jacking structures on both sides of the soil box, the adjacent end faces of the main pipe can be tightly fitted to simulate the initial state. Unloading the jacking force from the jacking structures on both sides allows them to retract, moving the main pipe and creating a controllable axial separation gap between the two sets of pipes that were originally tightly connected by the joint. This allows for continuous control of the displacement, fully simulating the gradual evolution of the disconnection from the initial micro-gap to complete separation from the joint constraint. Simultaneously, by correlating the external water seepage volume corresponding to different pulling stages, a quantitative relationship between the disconnection gap and the external water seepage volume can be directly established, providing experimental basis for determining the pipe disconnection repair threshold and assessing leakage risk.

[0022] In one alternative embodiment, the simulation device for external water seepage induced by pipeline defect development further includes a monitoring mechanism, which includes at least one of a displacement sensor, an inclination sensor, a pore water pressure sensor, and a distributed sensing optical fiber.

[0023] Beneficial effects: By adding at least one of the following: displacement sensor, tilt sensor, pore water pressure sensor, and distributed sensing fiber optic cable, the displacement sensor can accurately measure the misalignment offset or dislocation gap length; the tilt sensor can capture the pipe section rotation angle; the pore water pressure sensor can reflect the dynamic changes in the water pressure around the pipe; and the distributed sensing fiber optic cable can acquire continuous strain and temperature distribution along the pipe axis. In use, the type and number of sensors can be selected as needed, working collaboratively to acquire multi-dimensional data such as pipe deformation, soil response, and seepage field evolution, providing a complete experimental dataset for revealing the intrinsic coupling mechanism between defect development and external water infiltration. Simultaneously, cross-validation and verification can be performed to eliminate anomalies or drift that may exist in a single sensor, improving the reliability of the data.

[0024] Secondly, the present invention also provides a simulation method for external water seepage induced by pipeline defect development, which uses the simulation device for external water seepage induced by pipeline defect development provided in the first aspect, including the following steps: S1: filling soil in layers in a test soil box and burying a test pipeline at a preset depth; S2: injecting water into the test soil box to the design water level and keeping it stable; S3: continuously driving the movable pipe segment relative to the pipeline body through a driving mechanism to continuously change the geometric characteristic parameters of the pipeline defect, simulating the dynamic development process of the pipeline defect from the initial state to the expanded state; S4: measuring the amount of external water seepage during the dynamic development process and recording the leakage data corresponding to different geometric characteristic parameters.

[0025] Beneficial effects: By continuously and smoothly changing the position or angle of the moving segments through the drive mechanism, the geometric characteristic parameters of the defects (such as crack width, length, misalignment offset, and dislocation gap) continuously increase or decrease during the test, thus completely recording the real-time change curve of external water seepage throughout the entire process of the defect gradually expanding from an initial small state to a significant state. Simultaneously, in the same test, different drive mechanisms can be controlled in stages according to a preset strategy, obtaining leakage data under multiple parameter combinations in a single backfill and test. This avoids data dispersion caused by differences in soil and backfill conditions between different specimens, significantly improving the reliability of the test data. For example, first, control the rotating segments in the middle layer to increase the width of the circumferential crack while keeping the length constant; then control the pulling segments in the inner and outer layers to increase the length of the axial crack while keeping the width constant; finally, both change synchronously. Furthermore, the simulation process can approximate the actual defect evolution law as needed. The measured dynamic response law of external water seepage with defect development can be directly used to verify numerical models, derive empirical formulas, or formulate early warning thresholds for pipeline inspection and repair, providing more accurate experimental basis for pipeline disease diagnosis. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 A top cross-sectional view of a simulation device for external water seepage induced by pipeline defect development, provided in an embodiment of the present invention. Figure 2 Another top-view cross-sectional schematic diagram of the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention; Figure 3 This is a three-dimensional schematic diagram of the main body of the pipeline in the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention. Figure 4 for Figure 3 A magnified view of part A in the middle; Figure 5 for Figure 3 A magnified view of part B in the middle section; Figure 6 for Figure 3 A magnified view of part C in the middle; Figure 7 for Figure 3 A magnified view of part D in the middle; Figure 8 Another three-dimensional schematic diagram of the main body of the pipeline in the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention; Figure 9 for Figure 8 A magnified view of part E in the middle; Figure 10 for Figure 8 A magnified view of part F in the middle section; Figure 11 A three-dimensional schematic diagram of the axial crack simulation structure and the circumferential crack simulation structure in the simulation device for simulating the infiltration of external water induced by pipeline defect development provided in an embodiment of the present invention; Figure 12 This is a side view of the axial crack simulation structure and the circumferential crack simulation structure in the simulation device for simulating the infiltration of external water induced by pipeline defect development provided in an embodiment of the present invention. Figure 13 This is a three-dimensional schematic diagram of the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention, in which the splicing joint extends at a certain angle to the pipeline axis. Figure 14This is a schematic diagram of the drive mechanism installed on the pipe installation hole in the simulation device for induced external water seepage caused by pipe defect development provided in an embodiment of the present invention. Figure 15 A side view of the drive mechanism of the simulation device for induced external water seepage caused by pipeline defect development, provided in an embodiment of the present invention, installed on the pipeline installation opening. Figure 16 A schematic diagram of the drive mechanism connecting the middle layer rotating pipe segment in the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention. Figure 17 This is a schematic diagram of the drive mechanism in the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention. Figure 18 A three-dimensional schematic diagram showing the connection between the mounting platform, driver, moving platform, slide rail, screw rod propulsion shaft and first transmission assembly in the simulation device for induced external water seepage caused by pipeline defect development provided in an embodiment of the present invention. Figure 19 A top cross-sectional view of the connection between the mounting platform, driver, moving platform, slide rail, screw rod propulsion shaft and first transmission assembly in the simulation device for induced external water seepage caused by pipeline defect development provided in an embodiment of the present invention. Figure 20 This is a schematic diagram of the lifting device in the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention. Figure 21 This is a schematic diagram of the connection between the main body of the pipe and the flat-mouth plug fitting in the simulation device for external water seepage induced by pipe defect development provided in an embodiment of the present invention. Figure 22 This is a schematic diagram of the main pipe structure in the simulation device for external water seepage induced by pipe defect development provided in an embodiment of the present invention. Figure 23 A schematic diagram of the flat-mouth plug-in connection structure in the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention; Figure 24 A schematic diagram of the connection between the main body of the pipe and the joint in the simulation device for induced external water seepage caused by pipe defect development provided in an embodiment of the present invention; Figure 25 A schematic diagram of the flat-mouth plug-in connection structure in the simulation device for external water seepage induced by pipeline defect development provided in an embodiment of the present invention; Figure 26 This is a schematic flowchart of a simulation method for external water seepage induced by pipeline defect development, provided in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 1. Test soil box; 101. Pipe installation opening; 102. Fixed base plate; 103. Movable base plate; 2. Test piping; 201. Pipe body; 2011. Insertion groove; 2012. Mounting hole; 202. Assembled segments; 203. Joint; 204. First outer pull-out segment; 205. First inner pull-out segment; 206. Second outer pull-out segment; 207. Second inner pull-out segment; 208. Middle rotating segment; 209. First segment installation area; 2091. First installation groove; 2092. First sealing strip installation groove; 2093. Abutment groove; 210. Second segment installation area; 2101. Assembled segment splicing area; 2102. Assembled segment storage area; 2103. 2104. Second sealing strip mounting groove; 2105. Circumferential abutment groove; 211. Circumferential sealing strip mounting groove; 212. Third segment mounting area; 2121. Second mounting slide groove; 2122. Fourth segment mounting area; 213. Third mounting slide groove; 214. Third sealing strip mounting groove; 215. Fifth segment mounting area; 216. Rotating segment clamping area; 217. Rotating segment receiving area; 218. Fourth sealing strip mounting groove; 219. Sixth segment mounting area; 2100. Fourth mounting slide groove; 2100. Positioning component; 220. Vertical mounting plate; 221. Horizontal mounting plate; 3. Drive mechanism; 301. Mounting base; 302. Segment holder; 303. Rotating assembly; 304. Mounting platform; 305. Driver; 306. Moving platform; 307. Segment holder connecting frame; 308. Drive chain; 309. Sliding rail; 310. Sliding block; 311. Linkage mechanism; 313. Slide rail; 314. Screw drive shaft; 315. First transmission assembly; 316. Mounting bracket; 4. Lifting device; 401. Support plate; 402. Lifting frame; 403. Hydraulic telescopic rod; 404. Base frame; 405. Rotary wheel; 406. Drive component; 407. Second transmission assembly; 408. Rotary shaft; 409. Guide rail; 5. Flat-mouth plug-in component; 501. Plug-in component body; 5011. First locking groove; 5012. First connecting hole; 5013. Fifth sealing strip mounting groove; 502. Stop component; 5021. First part removal groove; 6. Pipe joint; 601. Joint body; 6011. Second locking groove; 6012. Second connecting hole; 6013. Sixth sealing strip mounting groove; 602. Baffle connector; 6021. Second part removal groove; N, one end of the main body of the pipe along the axial direction; M, the other end of the main body of the pipe along the axial direction; R is one end of the sliding track; L is the other end of the sliding track. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] According to embodiments of the present invention, on one hand, a simulation device for external water seepage induced by pipeline defect development is provided, such as... Figures 1 to 25 As shown, it includes a test soil box 1, a test pipeline 2, and a drive mechanism 3.

[0031] The test pipeline 2 is buried in the soil of the test soil box 1, and the test pipeline 2 includes a pipeline body 201 and at least one set of defect simulation structures set on the pipeline body 201. The defect simulation structure includes at least one movable segment, and a pipeline defect is formed between the movable segment and the pipeline body 201. The driving mechanism 3 is connected to the movable segment and is used to drive the movable segment to move continuously relative to the pipeline body 201 to change the geometric characteristic parameters of the pipeline defect, thereby simulating the dynamic development process of the pipeline defect from the initial state to the expanded state.

[0032] By setting up movable segments independently controlled by the drive mechanism 3, the rotation angle and pulling stroke of the segments can be continuously and precisely controlled, thereby completely reproducing the progressive development process of defects in a single test.

[0033] For example, axial cracks can be initially formed by slightly rotating the segments, then the rapid axial extension can be simulated by pulling the segments, and finally the crack opening and expansion can be simulated by continuous rotation; misalignment defects can be simulated by controlling the bottom plate to descend step by step, simulating the continuous offset process of the joint from slight misalignment to severe misalignment.

[0034] The simulated defects are made to closely resemble actual defects in terms of morphology, location, and mechanical boundary conditions. This allows the experimental data to accurately correspond to the time series and grade evolution of defect development, providing technical support for revealing the dynamic response law between external water infiltration and defect development.

[0035] It should be noted that this embodiment does not impose specific limitations on the dimensions, material, and soil filling method of the test soil box 1, as long as it can accommodate the test pipeline 2 and provide controllable boundary conditions.

[0036] As one implementation method, the side plate of the test soil box 1 is made of transparent material, such as plexiglass, which facilitates the observation of soil deformation and seepage path around the pipe. The test process is visualized and the influence of defect development on the infiltration morphology of external water can be recorded intuitively.

[0037] As another implementation method, the side plate of the test soil box 1 is made of stainless steel plate and has a reserved observation window. It has high structural strength and can withstand large soil pressure and water pressure, making it suitable for deep buried pipelines or high water head conditions.

[0038] In one embodiment, such as Figures 11 to 13 As shown, the defect simulation structure includes an axial crack simulation structure, which includes at least one rotatable assembly of pipe segments 202. The assembly of pipe segments 202 consists of at least two circumferentially assembled pipe segments 202. The splicing joint 203 between the two pipe segments 202 extends along the pipeline axis to form a straight axial splicing joint 203, or extends at a certain angle to the pipeline axis, such as 30°, 45° or 60°, to form an oblique splicing joint 203.

[0039] By setting at least two segments joined together circumferentially, and making the joint 203 of the two segments along the axial direction or at any angle intersecting the axial direction, it is possible to simulate axial cracks and diagonal cracks. Furthermore, by replacing the segments 202 with different angles, various diagonal crack conditions can be simulated, overcoming the limitation of existing technologies that can only simulate notches in a single direction, and making the test results more representative.

[0040] Simultaneously, it can conduct variable experiments to support comparative studies on the impact of crack orientation on external water infiltration, providing experimental methods and key data for establishing direction-dependent leakage prediction models. For example, while keeping parameters such as crack width and length constant, only the angle between the splice joint 203 and the axis can be changed to quantitatively study the impact of crack orientation on seepage morphology, leakage volume, and the extent of soil collapse around the pipe.

[0041] Furthermore, as an independent and replaceable module, the assembled pipe segment 202 only requires the pre-preparation of pipe segment pairs with different splicing seam 203 angles. This allows for rapid switching of test conditions on the same pipeline body 201 without the need to disassemble and reassemble the entire pipeline, replace the soil, or refill the soil. This significantly shortens the preparation time for multi-angle comparison tests and avoids data dispersion caused by soil differences between different test batches, thereby improving the comparability and reliability of test results.

[0042] It should be noted that this embodiment does not specifically limit the number, material, or splicing method of the assembled segments 202, as long as relative rotation can be achieved and a controllable gap can be formed.

[0043] As one embodiment, the spliced ​​segment 202 is composed of two semi-circular segments, and the splicing seam 203 is straight. Its structure is simple, easy to process and seal.

[0044] As another implementation, the spliced ​​segment 202 consists of three or more arc-shaped segments, and the splicing joint 203 can be designed as a broken line or curve (such as a wave), which can simulate more complex crack morphologies, such as sawtooth cracks or fatigue cracks.

[0045] In one embodiment, such as Figure 11 and Figure 12 As shown, the axial crack simulation structure also includes a first outer layer pull-out tube segment 204 and a first inner layer pull-out tube segment 205 that can move along the axial direction. The first outer layer pull-out tube segment 204 and the first inner layer pull-out tube segment 205 are respectively arranged on the radial outer side and the radial inner side of the assembled tube segment 202 group.

[0046] By setting up an axially movable first outer layer pull-out tube segment 204 and a first inner layer pull-out tube segment 205, the axial length of the crack can be controlled independently. Combined with the control of the circumferential width of the crack by the spliced ​​tube segment 202 group, the influence of width and length on the amount of infiltration of external water can be studied separately in the same experiment. This avoids the data confusion caused by the coupling of size parameters in the traditional fixed gap scheme and provides a clearer experimental basis for establishing a high-precision leakage prediction model.

[0047] At the same time, it can achieve phased and hierarchical control, realistically reproduce the development process of cracks, and make up for the shortcomings of existing technologies that can only simulate through cracks.

[0048] In addition, the multi-layered pull-out structure, compared with the existing technology that requires pre-excavation of the soil or overall movement of the pipeline, has a smaller annular gap due to the thinner thickness of each pull-out segment. Therefore, it will not cause significant soil settlement or hole collapse, which can reduce the interference of human factors on the interaction between the soil and the pipeline during the test, and make the measured internal seepage more closely reflect the actual working conditions.

[0049] It should be noted that this embodiment does not impose specific limitations on the thickness, material, and lubrication method of the pull-out segments, as long as they can move smoothly along the axial direction and cause minimal disturbance to the soil.

[0050] As one implementation method, the outer wall of the first outer layer pull-out segment 204 is coated with paraffin or lubricating grease, which can significantly reduce the frictional resistance during the pull-out process and reduce the disturbance to the surrounding soil.

[0051] As another implementation, the outer wall of the first outer pull-out tube 204 is provided with balls or pulleys, which can reduce the coefficient of friction and the lubricating material will not contaminate the soil, making it suitable for tests that require analysis of the chemical composition of the soil.

[0052] In one embodiment, the axial crack simulation structure is provided with several installation areas, which are respectively used to install the first outer layer pull-out tube segment 204, the first inner layer pull-out tube segment 205 and the assembled tube segment 202 group.

[0053] It should be noted that the specific structure of each installation area is not specifically limited, as long as it can achieve segment installation, guidance and sealing.

[0054] As one implementation method, such as Figures 3 to 10 As shown, the installation area includes the first segment installation area 209.

[0055] Specifically, the first segment installation area 209 is provided with first installation grooves 2091 on both sides for assembling the first outer layer pull-out segment 204; the outer layer of the first installation groove 2091 is provided with a first sealing strip installation groove 2092 of the same length for installing sealing strips to form a seal for the axial splice joint.

[0056] The first segment installation area 209 has a circumferentially provided abutment groove 2093 at the cut-off position for the end of the first outer pull-out segment 204 to abut, and a circumferential sealing strip is installed inside the abutment groove 2093 to achieve the sealing of the circumferential splice.

[0057] During use, the dual positioning of the sliding groove and the abutment groove 2093 ensures the accurate installation position of the outer pull-out tube segment, while the sealing strip achieves a complete seal in the initial state, avoiding unexpected leakage before the test.

[0058] As another implementation method, such as Figures 3 to 10 As shown, the installation area also includes a second segment installation area 210.

[0059] Specifically, the second segment installation area 210 includes a segment splicing area 2101 and a segment storage area 2102, and the outer and inner walls at the separation point of the two are provided with axially extending second sealing strip installation grooves 2103.

[0060] Meanwhile, the cut-off position of the second segment installation area 210 is provided with two circumferential abutment grooves 2104, one inner and one outer. The upper wall of the outer abutment groove 2093 and the lower wall of the inner abutment groove 2093 are provided with circumferential sealing strip installation grooves 2105 of the same length.

[0061] Furthermore, a circumferential sealing strip mounting groove 2105 is also provided at the joint between the assembled tube segment 202 and the inner structure.

[0062] A multi-layered sealing structure is constructed to effectively prevent leakage of the rotating segments in the initial state, while the storage area provides rotation space for the rotating segments and avoids interference with other components during rotation.

[0063] As another implementation method, such as Figures 3 to 10 As shown, the installation area also includes a third segment installation area 211.

[0064] Specifically, the third segment installation area 211 has second installation grooves 2111 on both sides for assembling the first inner layer pull-out segment 205. The first inner layer pull-out segment 205 also uses groove guidance to ensure the straightness and stability of the pull-out action.

[0065] It should be noted that the first segment installation area 209, the second segment installation area 210 and the third segment installation area 211 are arranged radially from the outside to the inside at intervals, so as to correspond to the first outer layer pull-out segment 204, the assembled segment 202 group and the first inner layer pull-out segment 205 respectively.

[0066] Furthermore, the two axial ends of the pipe body 201 are marked as the N end and the M end, respectively. The first segment installation area 209 and the third segment installation area 211 extend from the N end of the pipe body 201 toward the M end, and their ends near the M end are a predetermined distance from the M end. The second segment installation area 210 is opened from the M end of the pipe body 201 toward the N end, and its end near the N end is a predetermined distance from the N end.

[0067] This arrangement allows the first outer layer pull-out tube segment 204, the assembled tube segment 202 group, and the first inner layer pull-out tube segment 205 to be staggered in the axial direction, which helps to install and drive each tube segment independently, thereby avoiding motion interference.

[0068] In one embodiment, such as Figure 11 and Figure 12 As shown, the defect simulation structure includes a circumferential crack simulation structure, which includes a second outer layer pull-out tube segment 206, a second inner layer pull-out tube segment 207, and a middle layer rotating tube segment 208 arranged radially from the outside to the inside along the pipe wall. The second outer layer pull-out tube segment 206 and the second inner layer pull-out tube segment 207 are axially movable and used to form a gap at the end of the tube segment along the circumferential direction of the pipe. The middle layer rotating tube segment 208 is rotatably arranged and used to control the extension length of the circumferential gap.

[0069] By axially moving the second outer layer pull-out tube segment 206 and the second inner layer pull-out tube segment 207, a circumferential crack existing only on the outer and / or inner wall can be formed at the pipe end, simulating an initial surface crack. Then, through the continuous rotation of the middle layer rotating tube segment 208, the crack is made to extend along the wall thickness direction, forming a complete circumferential crack, and the extension length of the circumferential crack is gradually adjusted. This forms a staged and layered control to accurately simulate the gradual development process of the circumferential crack on the pipe cross-section.

[0070] Meanwhile, by controlling the second outer layer pull-out tube segment 206, the second inner layer pull-out tube segment 207, and the middle layer rotating tube segment 208 respectively, the effects of crack length (circumferential range) and crack width (axial range) on the amount of external water seepage can be studied in the experiment. This provides decoupled experimental data for establishing a multi-element leakage model and overcomes the defect that traditional preset gaps cannot distinguish these parameters.

[0071] In addition, by using the incomplete rotation of the middle rotating segment 208, it is also possible to simulate the asymmetric damage morphology where cracks only appear in the local circumferential angle of the pipeline (such as cracks only in the upper half of the circle), which truly reflects the complex crack characteristics of the pipeline caused by uneven circumferential constraints or local corrosion.

[0072] It should be noted that this embodiment does not specifically limit the number of circumferential crack simulation structures or their arrangement on the pipeline; it is sufficient to simulate one or more circumferential cracks.

[0073] As one implementation method, a set of circumferential crack simulation structures is set in the middle of the pipeline body 201 to simulate the typical working condition of circumferential cracking in the middle of the pipeline.

[0074] As another implementation method, multiple independent circumferential crack simulation structures are set at both ends and the middle part of the pipeline body 201, which can simultaneously simulate the development and mutual influence of multiple circumferential cracks, and more closely resemble the actual scenario of a pipeline cracking at multiple weak points at the same time.

[0075] It should be noted that this embodiment does not impose specific limitations on the specific construction of each installation area in the circumferential crack simulation structure, as long as it can achieve layered pulling and rotation.

[0076] Preferably, such as Figures 3 to 10 As shown, the installation area also includes a fourth segment installation area 212, a fifth segment installation area 213, and a sixth segment installation area 214, which are used to install the second outer layer pull-out segment 206, the middle layer rotating segment 208, and the second inner layer pull-out segment 207, respectively.

[0077] It can be noted that the fourth segment installation area 212, the fifth segment installation area 213 and the sixth segment installation area 214 all extend from the N end of the main pipe body 201 towards the M end, with the same cut-off position and a large distance from the M end, which facilitates processing and assembly.

[0078] Specifically, the fourth segment installation area 212 is provided with third installation grooves 2121 on both sides, and the outer inner wall of the third installation grooves 2121 is provided with third sealing strip installation grooves 2122 of the same length.

[0079] The fifth segment installation area 213 specifically includes a rotating segment clamping area 2131 and a rotating segment receiving area 2132. The rotating segment receiving area 2132 is located in the middle of the pipe wall and has a large curvature in the circumferential direction. The outer wall surface at the separation point between the two is provided with an axially extending fourth sealing strip installation groove 2133.

[0080] The sixth segment installation area 214 is provided with a fourth installation groove 2141 on both sides.

[0081] In use, the second outer pull-out tube segment 206 is guided by the fourth mounting groove 2141 and sealed by the sealing strip. The middle rotating tube segment 208 can rotate at a certain angle within the receiving area without obstruction. The second inner pull-out tube segment 207 can also move axially. The three work together to realize the staged simulation of circumferential cracks.

[0082] Of course, in other alternative embodiments, the axial lengths of the fourth segment mounting area 212, the fifth segment mounting area 213, and the sixth segment mounting area 214 are different. For example, the length of the fifth segment mounting area 213 is greater than the lengths of the fourth segment mounting area 212 and the sixth segment mounting area 214, which helps to give the middle rotating segment 208 a longer guide section, thereby making its rotation more stable.

[0083] Through the layered installation zones described above, the second outer pull-out tube segment 206 and the second inner pull-out tube segment 207 can move axially, forming a circumferential gap at the pipe end; the middle rotating tube segment 208 can rotate between the clamping area and the receiving area, gradually changing the extension length of the gap in the circumferential direction. The sealing strip installation grooves provided in each installation zone can ensure structural sealing in the initial state.

[0084] It can be noted that the length of the assembled crack simulation pipe is greater than the distance between the pipe installation holes 101 on both sides of the test soil box 1, and the length of the middle rotating pipe segment extending outside the soil box is greater than that of the outer and inner pull-out pipe segments.

[0085] It can ensure that the drive mechanism 3 can be installed outside the soil box to rotate the tube segment, avoiding soil interference. At the same time, the stroke of the second outer layer pull tube segment 206 and the second inner layer pull tube segment 207 inside the soil box is sufficient to simulate the length of crack extension.

[0086] In one embodiment, the specific transmission method for the drive mechanism 3 to drive the segment rotation is not specifically limited, as long as the precise rotation of the segment can be achieved.

[0087] As one implementation method, such as Figures 14 to 16 As shown, the drive mechanism 3 includes a mounting base 301, a segment holder 302, a rotating assembly 303, a transmission chain 308, a sliding block 310, a sliding track 309, and a linkage mechanism 311.

[0088] Specifically, the mounting base 301 is fixedly installed on the outer periphery of the pipe installation hole 101 on the side plate of the test soil box 1, specifically located at the end of the corresponding spliced ​​pipe segment 202 or the middle rotating pipe segment 208. The mounting base 301 is firmly connected to the side plate of the test soil box 1 by bolts or welding, and its interior is provided with a cavity to accommodate the transmission chain 308 and the sliding track 309.

[0089] The two segment holders 302 are controlled by two independent rotating assemblies 303, and the rotation angle can be set as needed. They are used to clamp the ends of two adjacent segments 202 in the segment assembly 202. One end of each segment holder 302 is a claw structure that clamps the outer or inner wall of the segment end; the other end is connected to the sliding block 310 in the rotating assembly 303 through the linkage mechanism 311.

[0090] The rotating assembly 303 is equipped with two segment holders 302 that control the two segments respectively.

[0091] The sliding rail 309 is installed inside the mounting base 301, and its extension direction is consistent with the circumferential tangential direction of the pipe. The two ends of the rail are marked as R end and L end, respectively, to limit the movement range of the sliding block 310.

[0092] The sliding block 310 is slidably mounted on the sliding track 309 and can move between the R end and the L end. One end of the sliding block 310 is provided with a rack or a toothed surface that meshes with a gear.

[0093] One end of the transmission chain 308 is connected to the drive motor, and the other end forms a gear transmission with the sliding block 310 through a gear structure. When the drive motor starts, the transmission chain 308 drives the gear structure to rotate, thereby driving the sliding block 310 to move along the sliding track 309.

[0094] One end of the linkage mechanism 311 is fixedly connected to the sliding block 310, and the other end is fixedly connected to the segment holder 302. When the sliding block 310 moves, the linkage mechanism 311 drives the segment holder 302 and the segment being held to rotate synchronously around the pipeline axis.

[0095] When it is necessary to increase the crack width, the drive motor is controlled to make the transmission chain 308 drive the gear structure to rotate in the forward direction. The sliding block 310 moves from the R end to the L end, and the segment holder 302 is driven to rotate through the linkage mechanism 311. The spliced ​​segment 202 (or the middle layer rotating segment 208) then rotates away from the initial sealing position to form a gap.

[0096] It should be noted that the rotating assembly 303 can also use a servo motor to directly drive the worm gear reducer, which in turn drives the segment holder 302. Its structure is more compact and has a self-locking function, which can prevent the segment from rotating due to external force.

[0097] Taking the drive mechanism 3 driving the assembled tube segment 202 to rotate from end R to end L as an example, the change in crack width Δ is calculated using the following formula: .

[0098] Wherein, the rotation angle is α, and r is the radius of the circle where the assembled tube segment 202 is located.

[0099] This calculation formula allows for the quantitative calculation of the real-time changes in crack width based on a preset angle, enabling precise control and measurement of crack opening and providing a mathematical basis for establishing a quantitative relationship between crack width and the amount of infiltration of external water.

[0100] In another implementation, the two segment holders 302 of the arc-shaped segment rotation mechanism are independently controlled by two rotation assemblies 303, and the rotation angle can be set separately as needed. It can independently simulate single-sided rotation, double-sided synchronous reverse rotation, or double-sided asynchronous rotation, realistically reflecting the uneven expansion characteristics of cracks in pipelines under complex stress conditions.

[0101] By directly clamping the assembled segment 202 or the middle rotating segment 208 with the segment holder 302, and with the precise drive of the rotating assembly 303, the rotation angle error can be controlled within a very small range. The real-time change of the crack width can be quantitatively calculated based on the preset angle, thereby realizing continuous, repeatable, and high-precision adjustment of the crack opening degree, providing a reliable basis for obtaining the quantitative relationship between crack width and external water infiltration.

[0102] It can be noted that the segment holder 302 is also used to hold the first outer layer pull-out segment 204, the first inner layer pull-out segment 205, the second outer layer pull-out segment 206, or the second inner layer pull-out segment 207.

[0103] Specifically, when the segment holder 302 is used to hold the assembled segment 202, it adopts an arc-shaped gripper structure. The inner arc surface of the gripper matches the shape of the outer wall surface of the end of the assembled segment 202. Its rear end is fixedly connected to the sliding block 310 via a linkage mechanism. One end of the linkage mechanism 311 is provided with a flange or threaded interface, which is bolted to the corresponding mounting hole 2012 on the holder body. The holder body is provided with at least one radial locking bolt or eccentric cam locking mechanism. When the locking bolt is rotated, its front end abuts against the outer or inner wall of the assembled segment 202, achieving circumferential fixation. Disassembly simply requires loosening the locking bolt to remove the gripper.

[0104] When the segment holder 302 is used to hold the rotating middle layer segment 208, it adopts an arc-shaped gripper with a different size than the aforementioned gripper. At this time, the front end of the gripper is provided with an annular flange, which cooperates with the annular groove opened on the end face of the rotating middle layer segment 208; or a radial expansion mandrel is used, which is inserted into the inner cavity of the end of the segment and fixed by expansion, and is also fixedly connected to the sliding block 310 in the arc-shaped segment rotation mechanism through the linkage mechanism 311.

[0105] Of course, when the segment holder 302 is used to hold the first outer layer pull-out segment 204, the first inner layer pull-out segment 205, the second outer layer pull-out segment 206, or the second inner layer pull-out segment 207, that is, when the segment holder 302 needs to pull the segment axially, it adopts C-shaped claws or clamping flat claws. The end of the pulled segment usually extends a certain length beyond the pipe port. The claws clamp the outer wall of the end of the segment from the upper and lower sides or the left and right sides. In order to avoid damaging the lubrication layer of the outer wall of the segment, the inner surface of the claws can be attached with rubber or polyurethane gaskets.

[0106] During installation, the clamp is fixedly connected to one end of the segment clamping connection frame 307. The segment clamping connection frame 307 is installed on the moving platform 306 of the telescopic device. The rear end of the clamp is provided with a connecting plate, which is fixedly connected to the end flange of the segment clamping connection frame 307 by bolts.

[0107] During clamping, manually tightened clamping bolts or quick-release clamps are used. Rotating the clamping bolts closes the jaws, clamping the end of the tube segment. For scenarios requiring automatic control, electric or pneumatic jaws can be used, with clamping and releasing controlled centrally by the test control terminal.

[0108] like Figures 17 to 19 As shown, the drive mechanism 3 also includes a mounting platform 304, a slide rail 313, a screw drive shaft 314, a driver 305, a moving platform 306, and a segment clamping and connecting frame 307.

[0109] The mounting platform 304 serves as the overall support base. The slide rail 313 is arranged on one side of the mounting platform 304 along its length, and the screw drive shaft 314 is arranged on the other side of the mounting platform 304 along its length and is parallel to the slide rail 313. The driver 305 is installed at one end of the mounting platform 304 and is connected to one end of the screw drive shaft 314 via the first transmission assembly 315. One side of the moving platform 306 is slidably connected to the slide rail 313, and the other side is helically connected to the screw drive shaft 314. The segment clamping and connecting frame 307 is installed above the moving platform 306, and a segment clamp 302 is provided at one end of it.

[0110] During operation, after the driver 305 starts, it drives the screw rod propulsion shaft 314 to rotate through the first transmission component 315. During the rotation of the screw rod propulsion shaft 314, it drives the moving platform 306 to move along the length direction, thereby driving the segment holder 302 and the segment being held to move axially synchronously.

[0111] By employing a helical drive pair between the screw drive shaft 314 and the moving platform 306, and in conjunction with the forward and reverse rotation control of the driver 305, the rotational motion can be smoothly converted into the linear movement of the segment holder 302. This provides micron-level displacement resolution, and the displacement is strictly linearly related to the rotation angle of the driver 305. This facilitates real-time recording of the pulling stroke and allows for precise control of each stage of crack length change from initial initiation to full expansion, providing a reliable basis for establishing a quantitative relationship between crack length and the amount of infiltration of external water.

[0112] Furthermore, by using threaded meshing transmission between the screw propulsion shaft and the moving platform 306, a self-locking characteristic is achieved, which avoids displacement rebound caused by soil resistance during the pulling process, ensuring that the crack length parameter remains constant during the test, and significantly improving the reliability of the data.

[0113] It should be noted that this embodiment does not specifically limit the type of the driver 305 or the specific form of the first transmission component 315, as long as it can provide controllable linear displacement.

[0114] In one implementation, the driver 305 is a servo motor, and the first transmission component 315 is a coupling, which has high displacement control accuracy and can provide real-time feedback of displacement.

[0115] As another implementation, the driver 305 is a manual rotary wheel 405 with a lead screw, which does not require an external power source and is suitable for simple tests in environments without power, and is also less expensive.

[0116] In addition, such as Figure 17 As shown, this embodiment also includes an installation bracket 316, which is used to flexibly adjust the height of the telescopic device according to the position of the segment to be pulled out.

[0117] As one implementation method, the mounting bracket 316 is a telescopic sleeve structure that can be locked with bolts, and its height can be flexibly adjusted as needed, and the adjustment is convenient.

[0118] As another implementation, the mounting bracket 316 is a column with a sliding groove. The telescopic device can move up and down along the sliding groove and be fixed with a positioning pin, which has a large adjustment range and reliable positioning.

[0119] During installation, the telescopic device is fixed to the mounting frame on the outside of the side plate of the test soil box 1, and the segment holder 302 extends through the pipe installation hole 101 to hold the end of the segment.

[0120] Initially, the moving platform 306 is located at one end close to the test pipe 2. Activating the driver 305 moves the moving platform 306 away from the test pipe 2, thus enabling the segment to be pulled outwards. During the pulling process, a lubricating material such as paraffin wax can be applied to the outer wall of the segment to reduce friction with the soil.

[0121] In one embodiment, the test pipeline 2 includes a staggered simulation pipe, and the test soil box 1 is provided with a bottom plate that can move up and down. The staggered simulation pipe is placed above the bottom plate, and the bottom plate is connected to a lifter 4, which is used to drive the bottom plate to move up and down so that the staggered simulation pipe produces vertical displacement.

[0122] The movable base plate 103 is driven to descend actively by the lifting device 4, which causes the misaligned simulated pipe placed above it to produce a controllable vertical displacement, while the pipe section limited by the adjacent fixed connecting pipe remains in its original position, thus forming a real vertical misalignment between the two pipes, completely reproducing the gradual evolution process of the misalignment from slight displacement to severe misalignment.

[0123] Meanwhile, by performing correlation analysis on the external water infiltration volume corresponding to different descent stages, a quantitative relationship between misalignment and external water infiltration volume can be directly established, providing experimental basis for pipeline defect classification assessment and repair threshold determination.

[0124] Furthermore, by employing a method that restricts the axial displacement of the fixed pipe and actively settles the simulated pipe, the vertical displacement of the staggered simulated pipe is slowly completed from bottom to top by the bottom plate. Its direction of movement is consistent with the direction of the soil's self-weight stress, resulting in minimal lateral compression and disturbance to the surrounding soil. This reduces the interference of the test operation on the interaction between the soil and the pipe, making the measured internal seepage data closer to the actual working conditions, and ensuring that the leakage test process can be accurately repeated.

[0125] It should be noted that this embodiment does not specifically limit the type of the lifting device 4 or the range of motion of the base plate, as long as it can achieve controllable vertical displacement.

[0126] As one implementation method, the lifting device 4 is a hydraulic jack with a large load-bearing capacity, suitable for deep backfill or large-diameter pipes.

[0127] As another implementation method, the lifting device 4 is an electric screw jack, which has high displacement control accuracy and can be linked with a computer to achieve automatic graded descent.

[0128] In addition, in this embodiment, the test soil box 1 can also be equipped with a combination of a fixed bottom plate 102 and a movable bottom plate 103, wherein the movable bottom plate 103 is provided with a sealing element around its perimeter to prevent soil loss.

[0129] Specifically, the lifting device 4 is movably installed at the bottom of the test soil box 1 to lift the movable base plate 103.

[0130] Among them, such as Figure 20As shown, the lifting device 4 includes a support plate 401, a lifting frame 402, a hydraulic telescopic rod 403, a base frame 404, a guide rail 409, and a rotating wheel 405. The support plate 401 is fixed to the top of the lifting frame 402. The fixed end of the hydraulic telescopic rod 403 is installed on the base frame 404, and its output end is connected to the lifting frame 402 for driving the lifting frame 402 to lift vertically. The guide rail 409 is set at the bottom of the housing. The base frame 404 is provided with a rotating wheel 405, which is rolled on the guide rail 409 and moves along the guide of the guide rail 409.

[0131] Furthermore, the lifting device 4 also includes a driving component 406 and a second transmission component 407. The driving component 406 can be powered by a motor or a hydraulic pump, and the second transmission component 407 can be a gear rack, lead screw, chain, or other transmission method to convert the rotational motion of the driving component 406 into the linear motion of the lifting frame 402.

[0132] This embodiment does not limit the specific type of the driving component 406 and the second transmission component 407, as long as the lifting frame 402 can be raised and lowered smoothly.

[0133] It can be noted that the lifting frame 402 adopts a scissor structure.

[0134] This embodiment does not limit the specific form of the lifting frame 402; it can be a single scissor lift, a double scissor lift, or a multi-stage scissor lift.

[0135] Preferably, the lifting frame 402 includes a rotating shaft 408. The output end of the hydraulic telescopic rod 403 is connected to the rotating shaft 408 of the lifting frame 402. By driving the rotating shaft 408 to rise and fall vertically, the opening and closing angle of the lifting frame 402 is changed, thereby adjusting the height of the lifting frame 402, and thus driving the support plate 401 fixed on its top to rise and fall vertically.

[0136] It can be noted that in this embodiment, the sealing element is a rubber bellows, which can adapt to the lifting and lowering of the base plate and provides a reliable seal.

[0137] As another implementation method, flexible sealing mortar is filled between the movable base plate 103 and the side wall of the soil box, which is low in cost and easy to replace.

[0138] In one embodiment, such as Figure 21 As shown, the test pipeline 2 includes a pipeline body 201 and a flat-end plug connector 5. The two ends of the pipeline body 201, which are axially arranged, are connected to the adjacent pipe sections through the flat-end plug connector 5.

[0139] It should be noted that this embodiment does not specifically limit the connection method between the pipe body 201 and the flat-mouth plug fitting 5, as long as it can be detachably fixed and reliably sealed.

[0140] As one implementation method, such as Figure 22As shown, both ends of the pipe body 201 are provided with insertion grooves 2011, and at least one locking element 215 (such as a protruding locking block) is provided on the wall of the insertion groove 2011; a through mounting hole 2012 is provided in the middle of the inner wall of the insertion groove 2011 facing the center of the pipe, and multiple mounting holes 2012 are evenly arranged in the circumference.

[0141] The inner wall of the pipe body 201 has at least four vertical mounting plates 216 with different cross-sections and orientations on the inside of the insertion slots 2011 at both ends, for installing displacement sensors; and at least one horizontal mounting plate 227 is also provided on one side of the inner wall of the pipe body 201 for installing dual-axis tilt sensors.

[0142] At the same time, such as Figure 23 As shown, the flat-mouth plug-in connector 5 includes a connector body 501 and a retainer 502. The outer diameter of the connector body 501 matches the inner diameter of the plug groove 2011. It has a first locking groove 5011 (matching the size of the locking member 215) and a first connecting hole 5012 (matching the size of the mounting hole 2012 and having a consistent circumferential orientation). The relative positions of the first locking groove 5011 and the first connecting hole 5012 correspond to the relative positions of the locking member 215 and the mounting hole 2012. A fifth sealing strip mounting groove 5013 is also provided in the middle of the outer wall of the connector body 501. The retainer 502 is located on the outside of the connector body 501, and its inner and outer diameters are the same as those of the pipe body 201. The retainer 502 has a first removal groove 5021 to facilitate the installation and removal of the flat-mouth plug-in connector 5.

[0143] During installation, the connector body 501 is inserted into the connector groove 2011, and the locking piece 215 is locked into the first locking groove 5011 to achieve axial positioning. The first connecting hole 5012 corresponds one-to-one with the mounting hole 2012. The flat-mouth connector 5 is fixedly connected to the pipe body 201 by bolts. The sealing strip is installed in the sealing strip mounting groove to achieve interface sealing.

[0144] As another implementation method, the pipe body 201 and the flat-mouth plug fitting 5 adopt a socket-type fit and do not use bolts. Instead, they are fixed by the interference fit between the locking piece 215 and the locking groove. This method is faster to assemble and disassemble, but has a lower load-bearing capacity.

[0145] It can be noted that when it is necessary to simulate pipe disconnection or multi-section connection, such as Figure 24 As shown, pipe joint 6 is used to connect adjacent pipe bodies 201.

[0146] This embodiment does not specify the exact structure of the pipe joint 6, as long as it can achieve a detachable and fixed connection between two pipe sections and has a sealing function.

[0147] As one implementation method, such as Figure 25 As shown, the pipe joint 6 includes two joint bodies 601 and a baffle connector 602 located between the two joint bodies 601.

[0148] During installation, the two connector bodies 601 are connected to the pipe bodies 201 on both sides respectively. Each connector body 601 is provided with a second locking groove 6011, a second connecting hole 6012, and a sixth sealing strip mounting groove 6013, the arrangement of which is the same as the arrangement of the corresponding structure on the flat-mouth plug-in component 5 (i.e., matching the locking component 215 and mounting hole 2012 in the plug-in groove 2011 of the pipe body 201). The baffle connector 602 has the same inner and outer diameters as the pipe body 201, and the baffle connector 602 has a second removal groove 6021 for easy installation and removal.

[0149] In use, first insert the two connector bodies 601 into the insertion slots 2011 of the adjacent pipe bodies 201 and fix them in place. Then, clamp the baffle connector 602 between the two connector bodies 601 and fix the three together using bolts or clips. A sealing strip is then installed in the sixth sealing strip mounting slot 6013 to ensure a sealed interface.

[0150] As another implementation method, the pipe joint 6 can adopt an integral flange structure, which directly connects the two pipe sections with bolts. The advantage is higher strength, but the volume is larger and it is not suitable for compact soil box tests.

[0151] Through the pipe joint 6, multiple pipe sections 201 can be connected in series to form a test pipe 2 of any length. They are easy to assemble and disassemble, and can be flexibly adjusted in the combination of pipe sections during simulations of misalignment and disconnection.

[0152] In one embodiment, to simulate pipeline misalignment defects, the middle of the test soil box 1 is enclosed by pairs of longitudinal and transverse plates to form an independent interval. The interval is equipped with a bottom plate that can move up and down independently, and the bottom plate is supported by a lifter 4 placed below.

[0153] Specifically, the bottom plate of the test soil box 1 includes a fixed bottom plate 102 and a movable bottom plate 103.

[0154] It should be noted that this embodiment does not specifically limit the shape and size of the movable base plate 103 or the number of lifting devices 4, as long as it can achieve local settlement.

[0155] In one implementation, the movable base plate 103 is a rectangular steel plate with sealing strips around its perimeter that slide and seal with the longitudinal plates, transverse plates, and the bottom plate of the soil box. The lifting device 4 consists of four synchronously controlled hydraulic jacks, which are respectively supported at the four corners of the base plate, ensuring smooth lifting and preventing tilting.

[0156] During use, when laying the pipe, the staggered simulated pipe is placed in the middle of the test soil box 1 and directly above the movable base plate 103. Both ends of the staggered simulated pipe are connected to the main pipe body 201 by pipe joints 6. Flat-end plug fittings 5 ​​are installed at both ends of the main pipe body 201. At the position where they meet the staggered simulated pipe, displacement sensors are installed on the vertical mounting plate 216 according to the design points, and dual-axis tilt sensors are installed on the horizontal mounting plate 227. Temporary jacking structures, such as jacks, are installed on the outer sides of the two side plates where the door is opened in the test soil box 1. Jacking force is applied to both ends of the fixed connecting pipe to make the end faces of the fixed connecting pipe and the staggered simulated pipe fit tightly. After the backfilling is completed, the jacks are controlled to retract a small distance to remove the jacking force at both ends of the fixed connecting pipe, but a slight axial constraint is still retained to limit the displacement of the fixed connecting pipe. Then, the lifting device 4 under the movable base plate 103 is controlled to descend, and the soil above is displaced, causing the staggered simulated pipe to descend, forming two relative staggers between it and the fixed connecting pipe whose displacement is restricted.

[0157] As another implementation method, multiple independent intervals and multiple movable base plates 103 can be set in the soil box. A section of staggered simulated pipe is placed on top of each base plate. By controlling the descent height of different base plates, the uneven settlement of multiple pipe sections can be simulated. The advantage is that it is closer to the actual foundation settlement curve.

[0158] Through the above-mentioned internal structure of the soil box and the pipeline laying method, the occurrence of misalignment defects is entirely driven by the settlement of the bottom plate, and the relative displacement between the misalignment simulation pipe and the fixed connection pipe can be accurately measured by sensors, ensuring the accuracy and repeatability of the test data.

[0159] It should be noted that this embodiment does not specifically limit the relative position and number of the fixed base plate 102 and the movable base plate 103.

[0160] As one implementation method, such as Figure 2 As shown, most of the test soil box 1 has a fixed base plate 102, with one or more movable base plates 103 only set in the pre-set misalignment simulation area in the middle. The movable base plates 103 are equipped with seals around their perimeter to prevent soil loss. This satisfies the local settlement requirements of the misalignment simulation while ensuring the stability of other areas of the soil box.

[0161] As another implementation method, the entire test soil box 1 bottom plate is composed of multiple independent movable bottom plates spliced ​​together. Each bottom plate is equipped with a lifter 4, which can be arbitrarily combined to form complex foundation settlement curves (such as parabolic, sine curve, etc.), which can simulate any uneven settlement conditions, but the control cost is high.

[0162] By combining a fixed base plate and a movable base plate, the test device can flexibly switch between ordinary backfill tests and offset settlement tests as needed, thus expanding the applicability of the device.

[0163] Similarly, there are no specific limitations on the number or driving method of the lifting devices 4.

[0164] It should be noted that this embodiment does not specifically limit the form and installation method of the jacking structure, as long as a controllable axial thrust or tension can be applied.

[0165] As one implementation method, the jacking structure is a temporary jacking jack, which is installed on the outer side of the two side plates of the test soil box 1. It has a large thrust, controllable stroke, and can be controlled synchronously or asynchronously through a hydraulic station.

[0166] As another implementation method, the jacking structure is an electric push rod with a pressure sensor, which can monitor the jacking force in real time and avoid damage to the pipe joint 6 due to excessive jacking.

[0167] It can be noted that in this embodiment, the pipe joint 6 can adopt a modular structure with a sealing strip mounting groove and a locking groove.

[0168] As one implementation method, the connector body 601 of the pipe joint 6 is provided with a locking groove and a connection hole, and is fixed to the pipe body 201 by bolts, which makes the connection reliable and easy to disassemble.

[0169] As another implementation method, the pipe joint 6 adopts a socket-type fit and is supplemented with a clamp for locking, which makes the installation faster and is suitable for tests that require frequent replacement of pipe sections.

[0170] In one embodiment, the simulation device for external water seepage induced by pipeline defect development further includes a monitoring mechanism, which includes at least one of a displacement sensor, an inclination sensor, a pore water pressure sensor, and a distributed sensing optical fiber.

[0171] By adding at least one of the following: displacement sensor, tilt sensor, pore water pressure sensor, and distributed sensing fiber optic cable, the displacement sensor can accurately measure the misalignment offset or the length of the dislocation gap; the tilt sensor can capture the rotation angle of the pipe section; the pore water pressure sensor can reflect the dynamic changes in the groundwater pressure around the pipe; and the distributed sensing fiber optic cable can acquire the continuous strain and temperature distribution along the pipe axis.

[0172] When in use, the type and number of sensors can be selected as needed to work together and acquire multi-dimensional data such as pipeline deformation, soil response, and seepage field evolution as needed, providing a complete experimental dataset for revealing the intrinsic coupling mechanism between defect development and external water infiltration.

[0173] At the same time, they can be cross-verified and cross-checked to eliminate anomalies or drifts that may exist in a single sensor, thereby improving the reliability of the data.

[0174] It should be noted that this embodiment does not specifically limit the type, quantity, or location of sensors in the monitoring mechanism, as long as they can acquire the required physical quantities.

[0175] As one implementation method, a laser displacement sensor is installed on the vertical mounting plate 216 of the misaligned simulated pipe, a dual-axis tilt sensor is installed on the horizontal mounting plate 227, and multiple pore water pressure gauges are buried in the soil around the pipe, which can simultaneously obtain the misalignment offset, the pipe section tilt angle and the pore water pressure distribution.

[0176] As another implementation method, distributed sensing optical fibers are attached along the entire length of the pipeline and demodulated using a Brillouin optical time domain analyzer (BOTDA) to obtain continuous strain and temperature distribution, accurately locating the soil deformation area caused by leakage.

[0177] According to an embodiment of the present invention, in another aspect, a simulation method for simulating the infiltration of external water induced by the development of pipeline defects is also provided, which employs the simulation device for simulating the infiltration of external water induced by the development of pipeline defects provided in the first aspect.

[0178] like Figure 26 As shown, the simulation method includes the following steps: S1: Fill the test soil box 1 with soil in layers and bury the test pipe 2 at a preset depth; S2: Fill the test soil box 1 with water to the design water level and keep it stable; S3: Drive the movable pipe segment to move relative to the pipe body 201 continuously through the drive mechanism 3, so as to continuously change the geometric characteristic parameters of the pipe defect and simulate the dynamic development process of the pipe defect from the initial state to the expansion state; S4: During the dynamic development process, measure the amount of external water seepage and record the leakage data corresponding to different geometric characteristic parameters.

[0179] By continuously and smoothly changing the position or angle of the movable segment through the drive mechanism 3, the geometric characteristic parameters of the defect (such as crack width, length, misalignment offset, disjoint gap, etc.) are continuously increased or decreased during the test, thereby completely recording the real-time change curve of the external water infiltration volume throughout the entire process of the defect gradually expanding from the initial small state to the significant state.

[0180] Meanwhile, in the same test, different drive mechanisms 3 can be controlled in stages according to a preset strategy, and leakage data under multiple parameter combinations can be obtained in one backfill and one test, avoiding data dispersion caused by differences in soil and backfill conditions between different specimens, and significantly improving the reliability of test data.

[0181] For example: first control the rotation of the middle layer segment to increase the axial crack width while keeping the length constant; then control the pulling of the inner and outer layers segment to increase the axial crack length while keeping the width constant; finally, both change synchronously.

[0182] Furthermore, the simulation process can closely approximate the actual evolution of defects as needed. The dynamic response of the measured external water infiltration with defect development can be directly used to verify numerical models, derive empirical formulas, or formulate early warning thresholds for pipeline inspection and repair, providing more accurate experimental basis for pipeline disease diagnosis.

[0183] It can be explained that in step S1, in order to simulate the pipeline disconnection defect, the pipeline laying process includes: selecting two sections of pipeline body 201, installing a flat-end plug connector 5 at one end, and installing a pipe joint 6 at the other end; connecting several pipeline bodies 201 through the pipe joint 6 at one end, forming two sets of staggered simulated pipes; the two sets of staggered simulated pipes, i.e., the ends of the flat-end plug connectors 5 installed, abut against each other, with the abutment position located in the middle of the test soil box 1; installing displacement sensors on the vertical mounting plate 216 according to the design points to measure the length of the disconnection gap; temporarily installing a jacking structure on the outer side of the two side plates where the hole is opened in the test soil box 1, applying a jacking force to the outer ends of the two sets of staggered simulated pipes, so that the contact end faces of the two sets of fixed connecting pipes are tightly fitted; after the soil filling is completed and water is injected for stabilization, the jacking force applied to the outer ends of the two sets of staggered simulated pipes is removed, and the two sets of staggered simulated pipes can be pulled in opposite directions by retracting the jacking structure or by setting an additional pulling device, so that an axial gap is generated at the flat end of the fixed connecting pipe, simulating pipeline disconnection.

[0184] Using this method, the dissociation gap can be continuously and controllably increased during the experiment. The displacement sensor records the gap length in real time, and combined with the internal seepage measurement data, a quantitative relationship between the dissociation gap and the leakage amount can be established.

[0185] It should be noted that in step S2, this embodiment does not specifically limit the water injection method and stability criteria.

[0186] As one implementation method, water is slowly injected from the bottom of the soil tank through an automatic water inlet control system to avoid water flow eroding the soil. The water level fluctuation does not exceed the threshold within a continuous period of time as the basis for judging water level stability, ensuring that the starting conditions for leakage measurement are consistent.

[0187] As another implementation method, water is injected by top spraying to simulate rainfall infiltration conditions, which is closer to the surface water replenishment scenario.

[0188] It should be noted that in step S3, this embodiment does not specifically limit the driving sequence and speed.

[0189] As one implementation method, a hierarchical driving mode is adopted.

[0190] Specifically, after each drive, the defect parameters are kept constant for a target time of t minutes until the leakage volume stabilizes before the next drive is performed to obtain leakage data under quasi-steady state.

[0191] As another implementation method, a continuous slow driving mode is used to simulate the real-time leakage response during the dynamic development of defects, which can capture leakage abrupt change points.

[0192] In one embodiment, in step S3, when the defect simulation structure is an axial crack simulation structure, the simulation of the development process of the axial crack in the pipeline specifically includes the following steps: S301: drive the spliced ​​pipe segment 202 to rotate relative to each other to form an initial axial crack; S302: simultaneously pull out the first outer layer pull-out pipe segment 204 and the first inner layer pull-out pipe segment 205 to simulate the crack extending along the pipeline axis; S303: continue to drive the spliced ​​pipe segment 202 to rotate, and simulate the crack width to further expand.

[0193] In one embodiment, in step S3, when the defect simulation structure is a circumferential crack simulation structure, the simulation of the development process of the circumferential crack in the pipeline specifically includes the following steps: S304: Pulling outward synchronously the second outer layer pull-out tube segment 206 and the second inner layer pull-out tube segment 207 to form a narrow gap extending circumferentially at the end of the pipeline; S305: Driving the middle layer rotating tube segment 208 to rotate, so that the gap is connected in the direction of the pipe wall thickness, forming a leakage channel; S306: Continuing to rotate the middle layer rotating tube segment 208 and / or continuing to pull out the second outer layer pull-out tube segment 206 and the second inner layer pull-out tube segment 207 to simulate the expansion and opening of the circumferential crack in the cross section.

[0194] In one embodiment, in step S3, when the test pipeline 2 includes a misaligned simulation pipe, the simulated pipeline misalignment development process specifically includes the following steps: S307: Control the jacks set outside the test soil box 1 to retract, and remove the axial jacking force at both ends of the adjacent fixed connection pipe; S308: Control the lifting device 4 below the base plate to descend step by step, causing the misaligned simulation pipe to generate vertical displacement, forming a relative misalignment with the adjacent fixed connection pipe; S309: Record the misalignment offset and pipe section tilt angle in real time through displacement sensors and tilt sensors installed in the pipeline.

[0195] In one embodiment, in step S3, when the test pipeline 2 includes at least two pipeline bodies 201 connected by a pipe joint 6 and the test soil box 1 is provided with a jacking structure on the outside, the simulated pipeline disintegration development process specifically includes: S310: removing the jacking force applied to the outer end of the pipeline body 201 by the jacking structure; S311: controlling the jacking structure to drive at least one pipeline body 201 to move axially in opposite directions, so that the flat ends of adjacent pipeline bodies 201 generate an axial gap; S312: recording the length of the disintegration gap in real time by a displacement sensor installed in the pipeline.

[0196] It should be noted that this embodiment does not specifically limit the method of measuring leakage in step S4.

[0197] As one implementation method, installing a high-precision flow meter or electronic balance on the water inlet pipe to measure the cumulative water intake in real time has the advantages of high measurement accuracy and fast response.

[0198] As another implementation method, a water replenishment and balancing tank is set up outside the soil tank. The internal seepage volume is calculated by measuring the change in the water level in the tank. The advantage is that the system is simple and low in cost.

[0199] In addition, camera devices can be installed at both ends of the test pipe 2 to capture in real time the morphology of external water seepage during the defect development process (such as water droplet formation, water flow trajectory, soil collapse, etc.).

[0200] As one implementation method, a high-speed camera combined with a macro lens can be used to quickly capture seepage details.

[0201] As another implementation method, an infrared thermal imager is used to identify the seepage path by temperature difference, achieving visualization without adding tracers.

[0202] In one embodiment, soil strain and pore water pressure change data are collected simultaneously in steps S3 and S4 to establish a multi-parameter correlation between defect development, external water infiltration, and soil response.

[0203] In one embodiment, a camera device is installed at at least one end of the test pipe 2 to capture the morphology of external water seepage during the defect development process in real time during steps S3 and S4, which is used to assist in the analysis of seepage path and soil scour characteristics.

[0204] In one embodiment, after completing a defect development simulation test, each movable segment is reset to its initial position, the sealing strip is replaced, the soil is refilled, and the next test is conducted to obtain multiple sets of parallel test data for statistical analysis.

[0205] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A simulation device for external water seepage induced by pipeline defect development, characterized in that, include: Test soil box (1); Test pipe (2), the test pipe (2) is buried in the soil of test soil box (1), and the test pipe (2) includes a pipe body (201) and at least one set of defect simulation structures set on the pipe body (201). The defect simulation structure includes at least one movable segment, and a pipe defect is formed between the movable segment and the pipe body (201). The driving mechanism (3) is connected to the movable tube segment and is used to drive the movable tube segment to move continuously relative to the pipe body (201) in order to change the geometric characteristic parameters of the pipe defect.

2. The simulation device for external water seepage induced by pipeline defect development according to claim 1, characterized in that, The defect simulation structure includes an axial crack simulation structure, which includes at least one rotatable assembly of pipe segments (202). The assembly of pipe segments (202) consists of at least two circumferentially assembled pipe segments (202). The splicing seam (203) between the two pipe segments (202) extends along the pipeline axis or at a certain angle to the pipeline axis.

3. The simulation device for external water seepage induced by pipeline defect development according to claim 2, characterized in that, The axial crack simulation structure also includes a first outer layer pull-out tube segment (204) and a first inner layer pull-out tube segment (205) that can move along the axial direction. The first outer layer pull-out tube segment (204) and the first inner layer pull-out tube segment (205) are respectively arranged on the radial outer side and the radial inner side of the assembled tube segment (202) group.

4. The simulation device for external water seepage induced by pipeline defect development according to claim 3, characterized in that, The defect simulation structure includes a circumferential crack simulation structure, which includes a second outer layer pull-out tube segment (206), a middle layer rotating tube segment (208), and a second inner layer pull-out tube segment (207) arranged radially from the outside to the inside along the pipe wall. The second outer layer pull-out tube segment (206) and the second inner layer pull-out tube segment (207) are axially movable and used to form a gap at the end of the tube segment along the circumferential direction of the pipe. The middle layer rotating tube segment (208) is rotatably arranged and used to control the circumferential extension length.

5. The simulation device for external water seepage induced by pipeline defect development according to claim 4, characterized in that, The drive mechanism (3) includes: Mounting bracket (301); A segment holder (302) is mounted on the mounting base (301) and is used to hold the assembled segment (202) or the middle rotating segment (208). Rotating assembly (303) is used to drive the segment holder (302) to rotate.

6. The simulation device for external water seepage induced by pipeline defect development according to claim 5, characterized in that, The segment holder (302) is also used to hold the first outer layer pull-out segment (204), the first inner layer pull-out segment (205), the second outer layer pull-out segment (206), or the second inner layer pull-out segment (207). The drive mechanism (3) further includes: Mounting platform (304), one side of which is provided with a slide rail (313) along the length direction, and the other side is provided with a screw rod push shaft (314) parallel to the slide rail (313). The driver (305) is mounted on one end of the mounting platform (304) and is connected to one end of the screw drive shaft (314) via the first transmission assembly (315); The mobile platform (306) is slidably connected to the slide rail (313) on one side and helically connected to the screw rod propulsion shaft (314) on the other side. A segment clamping connection frame (307) is installed above the mobile platform (306), and a segment clamp (302) is provided at one end of the segment clamping connection frame (307). The driver (305) drives the screw propulsion shaft (314) to rotate, thereby causing the moving platform (306) and the segment clamping and connecting frame (307) to move axially.

7. The simulation device for external water seepage induced by pipeline defect development according to any one of claims 1-3, characterized in that, The test pipeline (2) includes at least two pipeline bodies (201) and a pipe joint (6) connecting adjacent pipeline bodies (201). The test soil box (1) is provided with a jacking structure on the outside for driving at least one pipeline body (201) to move axially.

8. The simulation device for external water seepage induced by pipeline defect development according to any one of claims 1-3, characterized in that, The test pipeline (2) also includes a staggered simulation pipe. The test soil box (1) is equipped with a bottom plate that can move up and down. The staggered simulation pipe is placed above the bottom plate. The bottom plate is connected to a lifter (4) to drive the bottom plate to move up and down so that the staggered simulation pipe can generate vertical displacement.

9. The simulation device for external water seepage induced by pipeline defect development according to any one of claims 1-3, characterized in that, It also includes a monitoring mechanism, which comprises at least one of a displacement sensor, a tilt sensor, a pore water pressure sensor, and a distributed sensing fiber.

10. A method for simulating the infiltration of external water induced by pipeline defect development, comprising using the simulation device for simulating the infiltration of external water induced by pipeline defect development as described in any one of claims 1-9, characterized in that, Including the following steps: S1: Fill the test soil box (1) with soil in layers and bury the test pipe (2) at a preset depth. S2: Fill the test soil box (1) with water to the design water level and keep it stable; S3: The moving segments are continuously driven to move relative to the main body of the pipeline (201) by the driving mechanism (3) to continuously change the geometric characteristic parameters of the pipeline defect and simulate the dynamic development process of the pipeline defect from the initial state to the expanded state. S4: During the dynamic development process, measure the amount of external water seepage and record the leakage data corresponding to different geometric characteristic parameters.

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