Stress analysis system and experimental method for vehicle rolling over defective urban gas pipelines

Abstract

The present invention discloses a system and experimental method for analyzing the stress of a defective urban gas pipeline when a vehicle runs over it. The system includes: a multi-defect experimental pipeline, a strain measurement system, a deformation measurement system and a terminal device; the strain measurement device of the strain measurement system is arranged on the inner surface of the defect on the multi-defect experimental pipeline; the deformation measurement device of the deformation measurement system is fixed in the multi-defect experimental pipeline and placed at the corresponding defect position; the terminal device is connected to the strain measurement system and the deformation measurement system for communication. The system and experimental method for analyzing the stress of a defective urban gas pipeline when a vehicle runs over it disclosed by the present invention provide finite element analysis of the gas pipeline when it is run over by a heavy vehicle, and provide the real strain and deformation data of the pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of stress and deformation testing of urban gas pipelines, and in particular to a system and an experimental method for analyzing the stress of a defective urban gas pipeline crushed by a vehicle. Background Art

[0002] Urban gas pipelines are one of the main ways to transport natural gas in cities and towns, and are security projects related to people's livelihood issues. Since urban gas pipelines were laid earlier and the speed of urban development is relatively fast, there are many intersections between temporary roads for engineering construction and urban main roads and urban gas pipelines. When gas pipelines are crushed by vehicles, they may be deformed and displaced, affecting the safe operation of the pipelines. In particular, when the pipeline is crushed by heavy vehicles many times, there are defects in the pipeline body, which can easily lead to large deformation of the pipeline, causing pipeline rupture and gas pipeline leakage accidents. Therefore, it is very necessary to study the deformation and force of defective urban gas pipelines when they are crushed by heavy vehicles.

[0003] At present, the research on the stress analysis of defective urban gas pipelines crushed by vehicles is mainly based on the simulation results of finite element software. The reliability of finite element simulation models and results is difficult to verify, there are few field test studies, which cannot provide sufficient data, and there are certain deficiencies in the experimental research. Summary of the invention

[0004] The technical problem to be solved by the present invention is to solve the problem that the stress analysis of vehicles running over defective urban gas pipelines is relatively small, sufficient data cannot be provided, and there are certain deficiencies in the experimental research.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A vehicle rolling over defective town gas pipeline stress analysis system comprises: a multi-defect test pipeline 10, a strain measurement system, a deformation measurement system and a terminal device; the strain measurement device 20 of the strain measurement system is arranged on the inner surface of the defect 11 on the multi-defect test pipeline 10; the deformation measurement device 30 of the deformation measurement system is fixed in the multi-defect test pipeline 10 and placed at the position corresponding to the defect 11; the terminal device is connected to the strain measurement system and the deformation measurement system for communication;

[0007] The design and production method of the multi-defect experimental pipeline comprises the following steps:

[0008] S10, determining pipeline information, multiple defect information, rolling vehicle information and test site environmental parameters;

[0009] S20, using modeling language commands, establishes a stress analysis model for rolled defective town gas pipelines, including:

[0010] S21, set the single defect town gas pipeline stress analysis model with head end defect to calculate the stress distribution when the vehicle runs over the pipeline;

[0011] S22, on the basis of the single-defect town gas pipeline stress analysis model, a multi-defect town gas pipeline stress analysis model including a middle section defect and a tail end defect arranged in sequence is set, and the stress of the pipeline crushed by a vehicle is calculated. If there is no influence, the distance between defects is determined; if there is a stress influence, the distance between defects is increased and recalculated;

[0012] S30, determining a multi-defect experimental pipeline specimen diagram of stress and deformation of a multi-defect town gas pipeline according to the calculation results;

[0013] S40, manufacturing a multi-defect test pipeline according to the multi-defect test pipeline sample diagram.

[0014] Advantages: When testing equipment and methods for measuring stress and deformation of defective urban gas pipelines crushed by vehicles, this system can effectively measure the strain and deformation data of the crushed pipelines in real time.

[0015] The present invention provides a method for determining the distance between defects. The head end boundary distance is determined by the outer diameter of the pipeline, the middle boundary distance, the edge-middle boundary distance and the tail end boundary distance are obtained by finite element analysis results, and the basic restrictions specified in this paragraph need to be met at the same time. The distance between defects is determined by the simulated stress state of each defect.

[0016] The multi-defect test pipeline can contain multiple defects of different sizes at the same time, and the measurement results do not interfere with each other when the rolling test is carried out on each defect, thus avoiding waste of test materials and improving the efficiency of data collection in the vehicle rolling pipeline test.

[0017] In one embodiment of the present invention, in step S21: the size of the determined head end defect is input into the single defect town gas pipeline stress analysis model, and it is determined that the head end boundary distance l1 between the axial edge of the head end defect and the edge of the pipeline is not less than 1.5 times the pipeline diameter D.

[0018] In one embodiment of the present invention, the stress calculation analysis is performed based on the front end boundary distance l1 to determine the first interval boundary distance l1 between the front end defect and the middle section defect without stress influence when the vehicle is rolling over. 12 .

[0019] In one embodiment of the present invention, the size of the determined defects at the middle section is input into the stress analysis model of the multi-defect town gas pipeline; the number of defects at the middle section is N;

[0020] Define the middle section position defect closest to the head end defect as the first middle section position defect. When setting the position parameters of the first middle section position defect:

[0021] The middle boundary distance l2 of the first middle section defect is greater than the first interval boundary distance l when the head end defect is rolled without stress 12 , and the intermediate boundary distance l2 is greater than 1.5 times the pipe diameter D;

[0022] A stress calculation analysis is performed with the middle boundary distance l2 to determine the second interval boundary distance between the first middle section position defect and the second middle section position defect without stress influence when the vehicle is rolling over;

[0023] The interval boundary distance between multiple mid-section defects is determined according to the following method:

[0024] The interval boundary distance between the Nth middle position defect and the N+1th middle position defect is taken as: the interval boundary distance between the N-1th middle position defect and the Nth middle position defect.

[0025] In one embodiment of the present invention, the position parameter of the first middle position defect is the first interval boundary distance l 12 As the minimum setting basis, if the first interval boundary distance l 12 If the intermediate boundary distance l2 is less than 1.5 times the pipe diameter D, the value of the intermediate boundary distance l2 is 1.5 times the pipe diameter D.

[0026] In one embodiment of the present invention, the size of the determined tail end defect is input into the stress analysis model of a multi-defect town gas pipeline, and when the tail end defect position parameter is set:

[0027] The edge-middle boundary distance l3 between the tail end defect and the mid-section defect is taken as: the interval boundary distance between the two mid-section defects closest to the tail end defect, and the tail end boundary distance l4 of the tail end defect from the edge of the pipeline is not less than 1.5 times the pipeline diameter D.

[0028] In one embodiment of the present invention, stress calculation and analysis is performed based on the edge-middle boundary distance l3, and a rolling load is applied to the defect at the middle position closest to the tail end defect to determine whether the tail end defect is affected. If the tail end defect is affected, the value of the edge-middle boundary distance l3 is re-determined, and the value of the tail end boundary distance l4 is not less than 1.5 times the pipe diameter D. If it is less than 1.5 times the pipe diameter D, the tail end defect cannot be processed on the pipe.

[0029] In one embodiment of the present invention, the head end defect, the plurality of defects at the middle section and the tail end defect are arranged in sequence according to the pipeline axis, and the axial center lines of the defects are on the same axis.

[0030] A method for analyzing the stress of a defective town gas pipeline when a vehicle runs over it is disclosed. The method uses the above-mentioned system for analyzing the stress of a defective town gas pipeline when a vehicle runs over it, and comprises the following steps:

[0031] S100, excavating a pipe trench, and hoisting a multi-defect test pipe 10 in the pipe trench, with the defect center point located at a 90° position of the pipe, and simply fixing the pipe;

[0032] S200, fixing the strain measurement device 20 on the inner surface of the defect 11, fixing the deformation measurement device 30 in the multi-defect test pipeline 10, and placing it at the position corresponding to the defect 11; connecting the strain measurement system and the deformation measurement system to the terminal device for communication, and debugging them online;

[0033] S300, corresponding to each pipeline defect center point, a white line is marked on the ground perpendicular to the pipeline, and the mark is used as a single-side tire running track indicator mark line of the rolling vehicle;

[0034] S400, burying the multi-defect test pipeline 10 equipped with the strain measuring device 20 and the deformation measuring device 30, using trench excavation soil as the burial soil, and compacting the soil after burial;

[0035] S500, zeroing the equipment, turning on the strain measurement system and the deformation measurement system, performing a balancing operation on each test point, and ensuring that the data displayed by the test point is normal;

[0036] S600, the vehicle slowly passes through the multi-defect test pipe 10 at a relatively low speed, ensuring that one side of the tires rolls over the top of the defect. When the rear wheel reaches the top of the pipe, it stops for a short time. The vehicle is started again to pass through the multi-defect test pipe 10. When the rear wheel of the vehicle completely leaves the multi-defect test pipe 10, the vehicle stops moving forward, reverses and rolls over the multi-defect test pipe 10 again. After the vehicle drives to the top of the multi-defect test pipe 10, it stops driving for a certain period of time, and then drives forward to leave the multi-defect test pipe 10.

[0037] The strain measurement system and the deformation measurement system are turned on to record data, and the data are recorded a few seconds before the front wheel passes directly above the multi-defect test pipe 10, and the data are classified and stored; and at least three rolling tests are performed on each defect. In one embodiment of the present invention, the data collected in the experimental method are processed according to time; and after the experiment is completed, the trench is excavated, and the multi-defect test pipe 10 after the test is transferred to a storage site, and the test site is restored.

[0038] Compared with the prior art, the beneficial effects of the present invention are: the present invention can simultaneously measure the strain and deformation of the gas pipeline when a heavy vehicle rolls over a defective urban gas pipeline, can record the strain and deformation data of the pipeline when it is rolled over, and provide the real strain and deformation data of the pipeline for finite element analysis when the gas pipeline is rolled over by a heavy vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of a multi-defect experimental pipeline according to an embodiment of the present invention.

[0040] Figure 2 FIG. 4 is a schematic diagram of a stress measurement device according to an embodiment of the present invention.

[0041] Figure 3 FIG. 4 is a schematic diagram of a strain measurement device according to an embodiment of the present invention.

[0042] Figure 4 A schematic diagram of establishing a stress analysis model for a defective pipeline according to an embodiment of the present invention.

[0043] Figure 5 This is a schematic diagram of a single-defect pipeline design sample diagram according to an embodiment of the present invention.

[0044] Figure 6 This is a schematic diagram of a multi-defect pipeline design sample diagram according to an embodiment of the present invention.

[0045] Figure 7 Schematic diagram of the displacement field of the pipeline and soil according to an embodiment of the present invention.

[0046] Figure 8 This is a schematic diagram of the pipeline stress field under vehicle load at the first section defect of an embodiment of the present invention.

[0047] Fig. 9 This is a diagram of a multi-defect experimental pipeline sample according to an embodiment of the present invention.

[0048] Fig.10 Schematic diagram of an actual multi-defect experimental pipeline according to an embodiment of the present invention.

[0049] Fig.11 Schematic diagram of an actual pipe trench according to an embodiment of the present invention.

[0050] Fig.12 This is a schematic diagram of the placement of a multi-defect experimental pipeline according to an embodiment of the present invention.

[0051] Fig.13 This is a schematic diagram of placing an actual multi-defect experimental pipeline into a trench according to an embodiment of the present invention.

[0052] Fig.14 Schematic diagram of the arrangement and numbering of multi-defect test pipelines according to an embodiment of the present invention.

[0053] Fig.15 Schematic diagram of strain data collection according to an embodiment of the present invention.

[0054] Fig.16 Schematic diagram of deformation data collection according to an embodiment of the present invention.

[0055] Fig.17 Schematic diagram of the pasting and processing of strain gauges according to an embodiment of the present invention.

[0056] Fig.18 FIG. 4 is a schematic diagram of the placement of a deformation sensor according to an embodiment of the present invention.

[0057] Fig.19 It is a schematic diagram of deformation collection results of actual on-site application of an embodiment of the present invention.

[0058] Fig. 20 It is a schematic diagram of strain collection results of actual on-site application of an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with the accompanying drawings of the specification.

[0060] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0061] See also Figures 1 to 3 As shown, the present invention provides a vehicle-rolled town gas pipeline force analysis system, comprising: a multi-defect test pipeline 10, a strain measurement system, a deformation measurement system and a terminal device. The strain measurement device 20 of the strain measurement system is arranged on the inner surface of the defect 11 on the multi-defect test pipeline 10, the deformation measurement device 30 of the deformation measurement system is fixed in the multi-defect test pipeline 10 and placed at the position corresponding to the defect 11, and the terminal device is connected to the strain measurement system and the deformation measurement system for communication.

[0062] See also Figures 4 to 9 As shown, in one embodiment of the present invention, a method for designing and manufacturing a multi-defect test pipeline includes the following steps:

[0063] S10, determining pipeline information, multiple defect information, rolling vehicle information and test site environmental parameters.

[0064] In this embodiment, the pipeline information includes the pipeline diameter, which is not less than 300 mm, the total length of the pipeline, which is not less than 8 m, the pipeline wall thickness and the pipeline mechanical properties. The defect information includes the number of defects, defect length, defect width and defect depth. The rolling vehicle information includes vehicle information including vehicle weight, vehicle tire width, vehicle tire number and vehicle axle number. The test site environmental parameters include temperature, maximum temperature difference within one day, soil cohesion, effective bulk density, friction angle, elastic modulus and Poisson's ratio.

[0065] Specifically, the test pipe is a spiral welded steel pipe made according to GB / T3091-2015 standard. Its material is Q235B, the diameter is 720mm, the pipe length is 12m, the wall thickness is 7.5mm, the mechanical properties are 235Mpa, the tensile strength is 390Mpa, the vehicle weight is 44490kg, the overall dimensions are length × width × height are 14390×2800×3800, the tire width is 315mm, the rear is a double-row double-tire type and the front is a double-row single-wheel model. The experimental temperature is 20℃, the cohesion of hard clay is 28kPa, the effective bulk density is 23000N / m3, the friction angle is 33°, the elastic modulus is 28GPa, and the Poisson's ratio is 0.32. The defect information is shown in Table 1:

[0066] Table 1 Defect information

[0067]

[0068] S20, using modeling language commands, establish a stress analysis model for compacted defective urban gas pipelines.

[0069] The stress analysis model of the rolled defective town gas pipeline is established by using APDL language commands. Both the pipeline and the soil are solid unit components, and the 170 contact unit and 173 target unit in the APDL language are used to establish the constraints of the inner surface of the soil and the outer surface of the pipeline. In view of the limited extension of the buried pipeline in actual working conditions, in order to restore the actual service process of the buried pipeline, the present invention uses symmetric boundary constraints to constrain the section of Z=0, that is, the extension surface of the pipeline and the soil. At the same time, the end surface away from the symmetry surface constrains the axial displacement of the soil and the pipeline.

[0070] S21, set the single defect urban gas pipeline stress analysis model with head end defect to calculate the stress distribution when the vehicle runs over the pipeline.

[0071] See also Figures 4 to 6 As shown, in one embodiment of the present invention, the vehicle load is applied by applying pressure at the corresponding node position above the head end defect, such as Figure 4 .

[0072] In this embodiment, the size of the determined head end defect is input into the single defect town gas pipeline stress analysis model, and the head end boundary distance l1 between the axial edge of the head end defect and the edge of the pipeline is determined to be not less than 1.5 times the pipeline diameter D, and the stress calculation analysis is performed based on the head end boundary distance l1 to determine the first interval boundary distance l between the head end defect and the middle section defect without stress influence when the vehicle is rolling over. 12 ,See Figure 5 shown.

[0073] S22, based on the single-defect urban gas pipeline stress analysis model, a multi-defect urban gas pipeline stress analysis model containing a middle position defect and a tail end defect set in sequence is set to calculate the stress of the pipeline when the vehicle runs over it. If there is no impact, the distance between defects is determined. If there is stress impact, the distance between defects is increased and recalculated.

[0074] See also Figures 4 to 6 As shown, in one embodiment of the present invention, the size of the determined middle section position defect is input into the multi-defect town gas pipeline stress analysis model. The number of middle section position defects is N, and the middle section position defect closest to the head end defect is defined as the first middle section position defect. When setting the position parameters of the first middle section position defect:

[0075] The middle boundary distance l2 of the first middle section defect is greater than the first interval boundary distance l when the head end defect is rolled without stress 12 , and the intermediate boundary distance l2 is greater than 1.5 times the pipe diameter D, such as Figure 6 shown.

[0076] The stress calculation and analysis is performed with the intermediate boundary distance l2 to determine the second interval boundary distance between the first middle section position defect and the second middle section position defect without stress influence when the vehicle is rolling over. There is no doubt that if the intermediate boundary distance l2 at this time is used for stress calculation and analysis, and affects the next middle section position defect, that is, affects the second middle section position defect, then the intermediate boundary distance l2 at this time should be increased.

[0077] Among them, the position parameter of the first middle position defect is the first interval boundary distance l 12 As the minimum setting basis, if the first interval boundary distance l 12 If the intermediate boundary distance l2 is less than 1.5 times the pipe diameter D, the value of the intermediate boundary distance l2 is 1.5 times the pipe diameter D.

[0078] And, the interval boundary distance between multiple mid-section position defects is determined according to the following method:

[0079] The interval boundary distance between the Nth middle position defect and the N+1th middle position defect is taken as: the interval boundary distance between the N-1th middle position defect and the Nth middle position defect.

[0080] In one embodiment of the present invention, the head end defect, the plurality of defects at the middle section and the tail end defect are arranged in sequence according to the pipeline axis, and the center lines of the defects are on the same axis.

[0081] In one embodiment of the present invention, the size of the determined tail end defect is input into the stress analysis model of the multi-defect town gas pipeline. At this time, the stress analysis model of the multi-defect town gas pipeline is based on the model of setting the head end defect and the middle section position defect, and continues to load the tail end defect. When setting the tail end defect position parameters:

[0082] The edge-middle boundary distance l3 between the tail end defect and the mid-section defect is taken as: the interval boundary distance between the two mid-section defects closest to the tail end defect, and the tail end boundary distance l4 of the tail end defect from the edge of the pipeline is not less than 1.5 times the pipeline diameter D.

[0083] The stress calculation and analysis is performed based on the edge-middle boundary distance l3, and the rolling load is applied to the defect in the middle section closest to the tail end defect to determine whether the tail end defect is affected. If the tail end defect is affected, the value of the edge-middle boundary distance l3 is re-determined, and the value of the tail end boundary distance l4 is not less than 1.5 times the pipe diameter D. If it is less than 1.5 times the pipe diameter D, the tail end defect cannot be processed on the pipe.

[0084] See also Figures 7 and 8 As shown, in one embodiment of the present invention, a vehicle load of 7200KN is applied to the defect at the head end, and the overall displacement deformation of the town gas pipeline is as follows Figure 7 As shown. Figure 7 It can be seen from the figure that the parameter model of the single-defect town gas pipeline stress analysis model established by the present invention can well simulate the influence of vehicle load on the stress and displacement field of the buried pipeline. Figure 7 The results of the buried pipeline and soil displacement field show that the defects on the surface of the urban gas pipeline are independent of each other, and only the soil and pipeline at the head end defect are affected by the vehicle load. When the load reaches 7200KN, the maximum deformation at the pipeline defect reaches 29.18mm, and the pipeline strain value is 1.03% at this time.

[0085] In order to analyze the stress of defective urban gas pipelines, the corresponding stress field distribution of urban gas pipelines is extracted as follows: Figure 6 As shown. Figure 8The von Mises equivalent stress at the tail end defect is distributed in [1.28MPa, 24MPa], indicating that the vehicle load has no effect on the pipeline at the middle section defect and the tail end defect.

[0086] S30, determining a multi-defect experimental pipeline specimen diagram of stress and deformation of a multi-defect town gas pipeline according to the calculation results;

[0087] S40, manufacturing a multi-defect test pipeline according to the multi-defect test pipeline sample diagram.

[0088] In one embodiment of the present invention, the spacing between defects can be determined based on the finite element analysis results, and the final multi-defect test pipeline is as follows: Fig. 9 According to the multi-defect test pipeline sample diagram, the pipeline is processed to finally obtain the multi-defect test pipeline 10 required for the test, as shown in FIG. Fig.10 shown.

[0089] See also Figures 1 to 20 As shown, the present invention also provides a method for analyzing the force of a defective town gas pipeline when a vehicle rolls over it:

[0090] The pipeline layout in the test method is based on the test pipeline size, pipeline diameter Dmm, pipeline length Lmm, parallel trench excavation, trench width W = D + 300mm, depth DH = D + 300mm, pipeline length GL = L + 1000mm, drainage pits are set at both ends of the trench, the distance between the trenches should be greater than the length of a vehicle body, and the pipeline is hoisted in the corresponding trench.

[0091] The arrangement of strain measurement points in the experimental method is to use a grinder to grind the corresponding center of each defect inner surface on the multi-defect experimental pipe 10, and use the defect center as the origin to grind out a 200mm*100mm rectangular area. The polished area should show metallic luster and be wiped with an alcohol cotton ball. The strain measurement device 20 is pasted 50mm above and below the center of the square area, and the strain measurement device 20 is treated with moisture-proof treatment, such as Figure 2 .

[0092] The arrangement of the deformation measuring points in the experimental method is to place the deformation measuring device 30 at the corresponding defect position and fix it with a magnetic support. Each defect corresponds to a deformation measuring device 30. The deformation measuring device 30 is placed as follows. Figure 3 .

[0093] In the experimental method, the strain measurement system and the deformation measurement system are debugged online, and the main purpose of the debugging is to ensure that each strain measurement device 20 and the deformation measurement device 30 is in a normal state and the data acquisition system works normally.

[0094] In the test method, the multi-defect test pipeline 10 carrying the strain measuring device 20 and the deformation measuring device 30 is buried in the soil excavated from the trench. After the burial is completed, the soil is compacted by a rolling machine.

[0095] In the experimental method, data is collected, equipment is zeroed, the strain measurement system and the deformation measurement system are turned on, and balancing operations are performed on each test point to ensure that the data at the test point is displayed normally.

[0096] The data acquisition method in the experimental method is that the vehicle slowly passes through the multi-defect test pipe 10 at a relatively low speed, ensuring that the tire on one side rolls over the top of the defect. When the rear wheel reaches the top of the pipe, it stops for a short time, and the vehicle is started again to pass through the pipe. When the rear wheel of the heavy vehicle completely leaves the pipe for 1m, the vehicle stops moving forward, reverses and rolls over the pipe again. After the vehicle drives to the top of the pipe, it stops for 1min, then drives forward and leaves the pipe. Turn on the strain data acquisition instrument and the displacement data acquisition instrument to record data, and start recording data 5s before the front wheel passes the top of the defective pipe, and the data is classified and stored. Perform at least three rolling tests on each defect.

[0097] The data collection method in the experimental method processes the test data according to time.

[0098] After the experiment is completed, the test lines of the strain measuring device 20 and the deformation measuring device 30 are first cleared out of the pipeline, and then the trench is excavated, and the multi-defect experimental pipeline 10 after the test is transferred to the storage site to restore the test site.

[0099] Specific example

[0100] See also Figures 1 to 20 As shown, in this embodiment:

[0101] 1. Multi-defect experimental pipeline design:

[0102] In this embodiment, the experimental pipe is a spiral welded steel pipe made according to GB / T3091-2015 standard. Its material is Q235B, the diameter is 720mm, the wall thickness is 7.5mm, and the number is 4. Three defects are designed for each pipe, such as Fig. 9 and Fig.10 .

[0103] 2. Experimental trench and pipeline layout:

[0104] A 50m×20m waste road surface was selected for direct excavation. Four pipe trenches with a width of 1.02m, a length of 11m and a depth of 1.1m were excavated using an excavator. Drainage pits were set at both ends of the pipe trenches to prevent groundwater from entering the pipelines. Fig.11After the trench is prepared, the multi-defect test pipeline is placed in the trench, and the pipeline defect is located at 45°, as shown in Figure 2. Fig.12 As shown in the figure, after the pipeline is placed in the trench, Fig.13 The four test pipes are numbered from north to south as pipe 3, pipe 2, pipe 4, and pipe 1. The arrangement distribution diagram and pipe defect distribution diagram are shown in Fig.14 After the pipeline is placed in the trench, the corresponding defect center point is marked, and a 0.3m soil layer is backfilled above the pipeline and compacted.

[0105] 3. Test vehicle

[0106] The test vehicle uses Zoomlion ZTC550H5 truck crane, with a deadweight of 44,490kg, overall dimensions of length × width × height of 14,390 × 2,800 × 3,800, tire width of 315mm, and a double-row dual-tire type at the rear.

[0107] 4. Strain test system

[0108] The strain measurement system is mainly composed of a strain measurement device 20, an acquisition and processing system. The strain signal measurement consists of a BFH120-3AA resistance strain gauge, a wire connection block and a shielded wire. The strain signal acquisition system consists of a DH3816N resistance strain gauge with 60 test channels. And a dedicated test computer equipped with a data acquisition system, such as Fig.15 .

[0109] 5. Deformation measurement system

[0110] The deformation measurement system is mainly composed of a deformation measurement device 30, and a collection and processing system. The deformation measurement device 30 is composed of a YWC strain displacement sensor and a shielded wire, and the displacement signal collection system is composed of a YBY-2001 dynamic and static strain test analyzer with 20 test channels.

[0111] The YBY-2001 dynamic and static strain test and analysis system is a strain test and analysis system for various resistance strain gauges and strain sensors, including full-bridge, half-bridge, and quarter-bridge. The entire system adopts a brand-new design and uses a 320*240 LCD display screen, which can collect and display all data of 20 channels at the same time. The system implements two operation modes, namely manual measurement and automatic collection by computer. The system uses a 24-bit high-resolution AD conversion chip, the data is stable and reliable, and each channel is an independent chip to collect data. Users can connect each channel to different types of full-bridge, half-bridge, and quarter-bridge sensors to collect data at the same time. Fig.16 Among them, the data acquisition systems of the resistance strain gauge and the strain test analyzer are both connected to the terminal device for communication.

[0112] 6. Strain measurement point arrangement

[0113] According to the structure and stress characteristics of the buried pipeline, axial and circumferential strain gauges are arranged at the exact center of the defect on the inner wall of the pipeline, and circumferential strain gauges are installed at the top of pipe No. 4 and at a 45° direction, such as Fig.17 .

[0114] 7. Place the displacement sensor

[0115] First, connect the displacement sensor to the support rod at the test site, and use tools to tighten the bolts to prevent the displacement sensor from rotating under external force. Then connect the sensor to the data acquisition instrument through a connecting line to observe whether the displacement response of the sensor is normal. If the response is abnormal, calibrate the sensor. After the displacement test device is assembled, the test personnel will bring it into the pipeline, turn on the magnetic suction function of the base and fix it to the pipeline, then adjust the fixing screws of the displacement sensor, make the top of the displacement sensor contact with the top of the pipeline, and then fix the displacement sensor. After installation, the effect is as follows: Fig.18 shown.

[0116] 8. Equipment adjustment

[0117] After the strain and deformation sensors are installed, the strain test system and displacement test system are debugged online. The main purpose of the debugging is to ensure that the strain gauges and displacement sensors are in normal condition and the data acquisition system works normally, so as to ensure the next test.

[0118] 9. Equipment zero balance

[0119] Connect the strain test line to the strain data acquisition instrument, and the displacement acquisition line to the displacement data acquisition instrument. First, turn on the strain data acquisition instrument, balance each measuring point, check the balance state, and adjust or re-mount the measuring points that do not meet the requirements. Secondly, turn on the displacement data acquisition, check whether the data of the displacement data acquisition instrument is normal, and clear the data. If the data is abnormal, adjust the displacement sensor.

[0120] 10. Vehicle crushing

[0121] The vehicle slowly passes through the defective pipeline at a low speed, ensuring that one side of the tire rolls over the defect. When the rear wheel reaches the top of the pipeline, it stops briefly and starts the vehicle again to pass through the pipeline. When the rear wheel of the heavy vehicle completely leaves the pipeline for 1m, the vehicle stops moving forward, reverses and rolls over the pipeline again. After the vehicle reaches the top of the pipeline, it stops for 1min, then drives forward and leaves the pipeline. The strain data acquisition instrument and displacement data acquisition instrument are turned on to record data. Data is recorded 5s before the front wheel passes the top of the defective pipeline, and the data is classified and stored.

[0122] 11. Experimental data processing

[0123] After the pipeline diameter change data and pipeline strain test data were collected, the pipeline deformation and defect strain change diagrams were sorted out after subsequent data processing. Fig.19 and 20 .

[0124] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0125] The above-described embodiments merely represent implementation methods of the invention. The protection scope of the present invention is not limited to the above-described embodiments. For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A system for analyzing the stress of a defective town gas pipeline crushed by a vehicle, characterized in that: include: A multi-defect test pipeline (10), a strain measurement system, a deformation measurement system and a terminal device; the strain measurement device (20) of the strain measurement system is arranged on the inner surface of the defect (11) on the multi-defect test pipeline (10); the deformation measurement device (30) of the deformation measurement system is fixed in the multi-defect test pipeline (10) and is placed at the position corresponding to the defect (11); the terminal device is communicatively connected with the strain measurement system and the deformation measurement system; The design and production method of the multi-defect experimental pipeline comprises the following steps: S10, determining pipeline information, multiple defect information, rolling vehicle information and test site environmental parameters; Among them, pipeline information includes pipeline diameter, total length, wall thickness and mechanical properties of pipeline; defect information includes defect quantity, defect length, defect width and defect depth; rolling vehicle information includes vehicle weight, vehicle tire width, vehicle tire quantity and vehicle axle quantity; S20, using modeling language commands, establishes a stress analysis model for rolled defective town gas pipelines, including: S21, set the single defect town gas pipeline stress analysis model with head end defect to calculate the stress distribution when the vehicle runs over the pipeline; S22, on the basis of the single-defect town gas pipeline stress analysis model, a multi-defect town gas pipeline stress analysis model including a middle section defect and a tail end defect arranged in sequence is set, and the stress of the pipeline crushed by a vehicle is calculated. If there is no influence, the distance between defects is determined; if there is a stress influence, the distance between defects is increased and recalculated; S30, determining a multi-defect experimental pipeline specimen diagram of stress and deformation of a multi-defect town gas pipeline according to the calculation results; S40, manufacturing a multi-defect test pipeline according to the multi-defect test pipeline sample diagram; Wherein, in step S21: input the determined size of the head end defect into the single defect town gas pipeline stress analysis model, and determine that the head end boundary distance l1 between the axial edge of the head end defect and the edge of the pipeline is not less than 1.5 times the pipeline diameter D; The stress calculation and analysis is performed based on the front end boundary distance l1 to determine the first interval boundary distance l between the front end defect and the middle section defect without stress influence when the vehicle is rolling over. 12 ; According to the determined size of the tail end defect, input it into the stress analysis model of multi-defect town gas pipeline, and set the tail end defect position parameters: The stress calculation and analysis is performed based on the edge-middle boundary distance l3 between the tail end defect and the middle section defect, and the rolling load is applied to the middle section defect closest to the tail end defect to determine whether the tail end defect is affected. If the tail end defect is affected, the value of the edge-middle boundary distance l3 is re-determined, and the value of the tail end boundary distance l4 is not less than 1.5 times the pipe diameter D. If it is less than 1.5 times the pipe diameter D, the tail end defect cannot be processed on the pipe; where l4 is the tail end boundary distance from the edge of the tail end defect to the edge of the pipe.

2. The vehicle rolling over defective town gas pipeline stress analysis system according to claim 1 is characterized in that: According to the determined size of the defects at the middle section, the defects are input into the stress analysis model of multi-defect town gas pipeline; the number of defects at the middle section is N; Define the middle section position defect closest to the head end defect as the first middle section position defect. When setting the position parameters of the first middle section position defect: The middle boundary distance l2 of the first middle section defect is greater than the first interval boundary distance l when the head end defect is rolled without stress 12 , and the intermediate boundary distance l2 is greater than 1.5 times the pipe diameter D; A stress calculation analysis is performed with the middle boundary distance l2 to determine the second interval boundary distance between the first middle section position defect and the second middle section position defect without stress influence when the vehicle is rolling over; The interval boundary distance between multiple mid-section defects is determined according to the following method: The interval boundary distance between the Nth middle position defect and the N+1th middle position defect is taken as: the interval boundary distance between the N-1th middle position defect and the Nth middle position defect.

3. The vehicle rolling over defective town gas pipeline stress analysis system according to claim 2 is characterized in that: The position parameter of the first middle position defect is the first interval boundary distance l 12 As the minimum setting basis, if the first interval boundary distance l 12 If the intermediate boundary distance l2 is less than 1.5 times the pipe diameter D, the value of the intermediate boundary distance l2 is 1.5 times the pipe diameter D.

4. The vehicle rolling over defective town gas pipeline stress analysis system according to claim 1 is characterized in that: The head end defect, multiple middle section position defects and tail end defect are arranged in sequence according to the pipeline axis, and the axial center lines of the defects are on the same axis.

5. A method for analyzing the stress of a defective town gas pipeline when a vehicle rolls over it, characterized in that: The application of the vehicle rolling over defective town gas pipeline stress analysis system according to any one of claims 1 to 4 comprises the following steps: S100, excavating a pipe trench, and hoisting a multi-defect test pipe (10) in the pipe trench; S200, fixing the strain measurement device (20) on the inner surface of the defect (11), fixing the deformation measurement device (30) in the multi-defect experimental pipeline (10), and placing it at the position corresponding to the defect (11); connecting the strain measurement system and the deformation measurement system to the terminal device for communication, and debugging them online; S300, corresponding to each pipeline defect center point, a white line is marked on the ground perpendicular to the pipeline, and the mark is used as a single-side tire running track indicator mark line of the rolling vehicle; S400, burying the multi-defect test pipeline (10) equipped with the strain measuring device (20) and the deformation measuring device (30), using the soil excavated from the trench as the burial soil, and compacting the soil after burying; S500, zeroing the equipment, turning on the strain measurement system and the deformation measurement system, performing a balancing operation on each test point, and ensuring that the data displayed by the test point is normal; S600, the vehicle slowly passes through the multi-defect test pipe (10) at a relatively low speed, ensuring that the tire on one side rolls over the top of the defect. When the rear wheel reaches the top of the pipe, it stops for a short time. The vehicle is started again to pass through the multi-defect test pipe (10). When the rear wheel of the vehicle completely leaves the multi-defect test pipe (10), the vehicle stops moving forward, reverses and rolls over the multi-defect test pipe (10) again. After the vehicle reaches the top of the multi-defect test pipe (10), it stops moving for a certain period of time, and then moves forward to leave the multi-defect test pipe (10). The strain measurement system and the deformation measurement system are turned on to record data, and the data is recorded a few seconds before the front wheel passes directly above the multi-defect test pipe (10), and the data is classified and stored; and at least three rolling tests are performed on each defect.

6. The experimental method for analyzing the stress of a defective town gas pipeline crushed by a vehicle according to claim 5 is characterized in that: The data collected in the experimental method are processed according to time; and after the experiment is completed, the trench is excavated, the multi-defect experimental pipeline (10) after the test is transferred to a storage site, and the test site is restored.

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