Pipeline whole-line stress analysis method

Abstract

The invention relates to a pipeline whole-line stress analysis method, which comprises the following steps of: acquiring the whole-line stress level of a long-distance pipeline through Abaqus finite element software, comparing according to critical failure stress determined by a user, and judging the safety state of the pipeline. Wherein the pipeline whole-line basic parameters are main basic data sources of whole-line stress analysis, indirect parameters are obtained after basic data are processed, a. Inp file needed by Abaqus finite element software analysis is constructed according to the process by means of the basic parameters and the indirect parameters, finally, the. Inp file is submitted to an Abaqus solver, and a pipeline whole-line stress analysis result is obtained. Compared with the prior art, the method for analyzing the whole-line stress of the long-distance pipeline is convenient, simple and rapid, complex pipeline routing, non-uniform pipe-soil interaction, ground surface settlement load and temperature difference load are included in the method, and solving of the whole-line stress can be completed and a result can be obtained through Abaqus software only by writing an. Inp file according to a process. The method is suitable for stress evaluation of an engineering field, and is convenient for large-scale use.

Description

Technical Field

[0001] The present invention belongs to the technical field of structural safety evaluation of oil and gas pipelines, and specifically relates to a method for analyzing the stress of the entire pipeline. Background Art

[0002] With the booming development of the pipeline industry, the safe operation and maintenance of long-distance pipelines are of great importance for the national pipeline network to achieve "one national network". Due to the diverse characteristics of the areas through which long-distance pipelines pass, during service, in addition to internal pressure loads, they are very likely to additionally bear surface displacement loads, expansion loads caused by temperature differences, traffic loads, etc. In addition, the failure of special structures such as elbows and girth welds is more obvious for additional loads. Therefore, if external loads can be reasonably considered in the design stage and reasonable pipeline routing optimization strategies and pipeline structure design parameters can be proposed based on the stress levels of the entire long-distance pipeline, then it is very likely to protect the safety status of long-distance pipelines from the source.

[0003] At present, there are mainly three methods to obtain the stress of pipelines. One is through theoretical analysis. Since the underlying logic of the analysis model only matches straight pipelines and is difficult to apply to the three-dimensional spatial routing of long-distance pipelines, the stress state of the entire line cannot be accurately evaluated. The second is to obtain it through pipeline detectors or other monitoring devices. There have always been uncertainties in the passability of detectors under external loads and the timeliness of stress. Monitoring devices often only monitor the stress of pipelines in special sections and it is difficult to obtain the stress of the entire line. The third is through numerical simulation. Commonly used ones include the continuous medium contact model and the soil spring model. The continuous medium contact model is difficult to meet the characteristics of long distance and three-dimensional spatial routing of long-distance pipelines, and its high calculation cost and high convergence difficulty make it inapplicable. The soil spring model is cumbersome to model in Abaqus software, unable to form a simple and smooth modeling process, and has too high requirements for the technical literacy of computing personnel.

[0004] The key problems in the method for analyzing the stress of the entire pipeline include: (1) the non-linear mechanical performance characteristics of the pipe material and the soil around the pipe, (2) the three-dimensional spatial distribution characteristics of the pipeline routing, and (3) the three-dimensional characteristics of the geographical location of the ultra-long distance characteristics of the long-distance pipeline. Therefore, in response to the actual needs of pipeline stress evaluation in engineering practice and combining the existing technical problems at present, the present invention proposes a method for analyzing the stress of the entire long-distance pipeline, and this method has the characteristics of simple calculation and high efficiency. Summary of the Invention

[0005] To overcome the defects of the prior art, the present invention provides a method for analyzing the stress of the entire long-distance pipeline.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for analyzing the stress of a long-distance pipeline throughout the line, which simulates the stress level of the long-distance pipeline, includes the following steps:

[0008] (1) Obtain the basic parameters of the entire pipeline;

[0009] (2) Solve the required indirect parameters according to the basic parameters;

[0010] (3) Compile the.inp file required for the analysis of Abaqus finite element software;

[0011] (4) Submit the.inp file to the Abaqus solver to obtain the stress analysis results of the entire pipeline.

[0012] The present invention has the following beneficial effects:

[0013] (1) The method for analyzing the stress of a long-distance pipeline throughout the line according to the present invention provides a reliable method for calculating the stress of the entire line in the technical field of safety evaluation of long-distance pipelines. The.inp file required for the analysis of Abaqus finite element software can be constructed according to the analysis flow chart. Compared with other methods for obtaining the stress of the entire line, the method of the present invention saves significantly in terms of economic cost, time cost, and practical results.

[0014] (2) The method for analyzing the stress of a long-distance pipeline throughout the line according to the present invention is simple and easy to use, and can be used for the stress analysis and structural safety evaluation of all long-distance pipelines.

[0015] (3) The method for analyzing the stress of a long-distance pipeline throughout the line according to the present invention supports the diameters, wall thicknesses, and steel grades of all in-service pipelines, has high model calculation accuracy, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic flow chart of the method for analyzing the stress of a long-distance pipeline throughout the line according to the present invention; Figure 2 is the stress analysis result of the entire pipeline calculated after submitting the.inp file according to the present invention; Figure 3 is the comparison result of the maximum Mises stress and the critical stress extracted along the line according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0017] The following further describes the present invention in detail with reference to the drawings:

[0018] As Figure 1 shown, the present invention provides a method for analyzing the stress of a long-distance pipeline throughout the line, characterized in that the long-distance pipeline is a buried pipeline, the load is the surface settlement load and the axial stress load caused by the temperature difference, and the pipeline length is not restricted in any way. The method for analyzing the stress of the long-distance pipeline throughout the line includes the following steps:

[0019] (1) Obtain the three-dimensional spatial routing coordinate matrix N of the entire pipeline, and classify it into the straight pipe section routing coordinate matrix N P and the elbow section routing coordinate matrix N E , the surface elevation matrix Z of the entire pipeline G , the curvature radius matrix R at each elbow E , the elastic modulus E and Poisson's ratio ν of the pipeline material, the pipeline diameter D, the pipeline wall thickness t, the thermal expansion coefficient α, the initial temperature T1, the changed temperature T2, the surface settlement u, the internal pressure P during pipeline operation, and the three-dimensional soil spring stiffness matrix T around the pipeline u 、ΔT、P u 、ΔP、Q u 、ΔQ u 、Q d 、ΔQ d .

[0020] (2) Calculate the indirect parameters required for evaluation based on the basic parameters, mainly including: the center coordinate matrix O of the curvature radius of the elbow section E and the distance matrix L between the i-th and (i + 1)-th coordinate positions of the matrix N P , and the calculation method is as shown in Formula 1 P .

[0021]

[0022] (3) In the.inp file of Abaqus software, input the three-dimensional spatial routing coordinate matrix N, and assign a node number to each coordinate. The pipeline node set is A Aba . If the node number of the starting point is a, then the node number of the second coordinate is a + L1, where L1 is rounded up. Then, construct the underground coordinate set B of the entire pipeline Aba , and the construction method is to take the matrix Z G - 15m. Finally, form the corresponding number set OA E and the underground center coordinate set OB Aba through the center coordinate matrix O Aba .

[0023] (4) Generate the straight pipe node set of the pipeline. The writing language in the.inp file is as follows:

[0024] *NGEN,NSET=NS(i)

[0025] A Aba (i),A Aba (i + 1),1

[0026] (5) Generate the elbow node set of the pipeline. The writing language in the.inp file is as follows:

[0027] *NGEN,LINE=C,NSET=NE(i)

[0028] A Aba (i),A Aba (i + 1),1

[0029] (6) Generate the surface node set, and the writing language in the.inp file is as follows:

[0030] *NGEN,NSET=NGS(i)

[0031] B Aba (i),B Aba (i + 1),1

[0032] *NGEN,LINE=C,NSET=NGE(i)

[0033] B Aba (i),B Aba (i + 1),1

[0034] (7) Set the node set according to the position of the settlement load to be applied, and the writing language in the.inp file is as follows:

[0035] *NSET,NSET=SUBPOINT(i)

[0036] B Aba (i)

[0037] (8) Set the boundary condition node set, and the writing language in the.inp file is as follows:

[0038] *NSET,NSET=BC

[0039] A Aba (i),B Aba (i)

[0040] (9) Generate the pipe elbow element, where C Aba is the number matrix of the element type, and the writing language in the.inp file is as follows:

[0041] *ELEMENT,TYPE=ELBOW31,ELSET=PIPES(i)

[0042] C Aba (i),A Aba (i),A Aba (i + 1)

[0043] *ELGEN,ELSET=PIPES(i)

[0044] C Aba (i),LP (i),1

[0045] (10) Define the pipe section type. The programming language in the .inp file is as follows:

[0046] *BEAM SECTION,SECTION=ELBOW,ELSET=PIPES(i),MATERIAL=STEEL

[0047] D / 2,t,0

[0048] O E (i)

[0049] 3,20,6

[0050] (11) Define the pipe-soil interaction unit, where D Aba It is a numbered set of PSI unit types. The language used in the .inp file is as follows:

[0051] *ELEMENT,TYPE=PSI34,ELSET=SOIL(i)

[0052] D Aba (i),A Aba (i),A Aba (i+1),B Aba (i+1),B Aba (i)

[0053] (12) Define the material properties of the pipeline. The language of the .inp file is as follows:

[0054] *MATERIAL,NAME=STEEL

[0055] *ELASTIC

[0056] E,ν

[0057] *Expansion

[0058] α

[0059] (13) Define the material properties of soil-pipe interaction. The programming language of the .inp file is as follows:

[0060] *PIPE-SOILINTERACTION,ELSET=SOIL(i)

[0061] *PIPE-SOILSTIFFNESS,TYPE=NONLINEAR,DIR=AXIAL

[0062] -T u (i),-ΔT(i)

[0063] 0,0

[0064] T u (i), ΔT(i)

[0065] *PIPE - SOIL STIFFNESS, TYPE=NONLINEAR, DIR=VERTICAL

[0066] -Q d (i), -ΔQ d (i)

[0067] 0,0

[0068] Q u (i), ΔQ u (i)

[0069] *PIPE - SOIL STIFFNESS, TYPE=NONLINEAR, DIR=HORIZONTAL

[0070] -P u (i), -ΔP(i)

[0071] 0,0

[0072] P u (i), ΔP(i)

[0073] (14) Define the initial temperature conditions and initial boundary conditions. The writing language in the.inp file is as follows:

[0074] *Initial Conditions, type=TEMPERATURE

[0075] A Aba , T1

[0076] *BOUNDARY

[0077] BC, 1, 1

[0078] BC, 2, 2

[0079] BC, 3, 3

[0080] BC, 4, 4

[0081] BC, 5, 5

[0082] BC, 6, 6

[0083] (15) Define the internal pressure load of the pipeline, temperature load, and define the pipeline settlement load. The writing language in the.inp file is as follows:

[0084] *STEP,NLGEOM

[0085] *static

[0086] 0.1,1.0,0.00001,0.15

[0087] *Dload

[0088] PIPES(i),PI,P,D - 2t

[0089] *Temperature

[0090] A Aba ,T2

[0091] *BOUNDARY

[0092] SUBPOINT(i),3,3,u

[0093] SUBPOINT(i),3,3,u

[0094] SUBPOINT(i),3,3,u

[0095] SUBPOINT(i),3,3,u

[0096] SUBPOINT(i),3,3,u

[0097] SUBPOINT(i),3,3,u

[0098] SUBPOINT(i),3,3,u

[0099] SUBPOINT(i),3,3,u

[0100] SUBPOINT(i),3,3,u

[0101] SUBPOINT(i),3,3,u

[0102] SUBPOINT(i),3,3,u

[0103] (16) Write the mechanical parameters to be solved. The writing language in the.inp file is as follows:

[0104] *ELEMENT OUTPUT,ELSET=PIPES(i)

[0105] S

[0106] *ELEMENT OUTPUT,ELSET=PIPES(i)

[0107] SF

[0108] *NODE OUTPUT, NSET=A Aba

[0109] RF, RM, U, UR

[0110] *EL PRINT, ELSET=PIPES(i), FREQUENCY=1

[0111] S

[0112] (17) Submit the calculation and obtain the full-line stress analysis results after completion.

[0113] The following is illustrated with specific Examples 1 and 2:

[0114] Example 1:

[0115] (1) Obtain the three-dimensional spatial routing coordinate matrix N of the entire pipeline, which is classified into the straight pipe section routing coordinate matrix N P and the elbow section routing coordinate matrix N E as shown in Table 1. The surface elevation matrix Z of the entire pipeline G , and the curvature radius matrix R at each elbow E as shown in Table 2. The three-directional soil spring stiffness matrix T around the pipeline u , ΔT, P u , ΔP, Q u , ΔQ u , Q d , ΔQ d as shown in Table 3. The elastic modulus E of the pipeline material is 210 GPa, the Poisson's ratio ν is 0.3, the pipeline diameter D is 0.25 '4 m, the wall thickness is 0.007719 m, the thermal expansion coefficient α is 1.16×10 -5 , the initial temperature T1 is 37.5 °C, the changed temperature T2 is 15.5 °C, the surface settlement u is -0.05 m, and the internal pressure P during pipeline operation is 7.9 MPa.

[0116] Table 1 Example matrices N, N P , N E

[0117]

[0118] ; Table 2 Example matrices Z G , R E , N E , H P

[0119]

[0120]

[0121] Table 3 Embodiment Matrix T u , ΔT, P u , ΔP, Q u , ΔQ u , Q d , ΔQ d

[0122]

[0123] (2) Calculate the indirect parameters required for evaluation based on the basic parameters. The calculation results of the center coordinate matrix O of the curvature radius of the elbow section are shown in Table 4. The matrix L calculated by Formula 1 E is shown in Table 4 P as shown in Table 4

[0124] Table 4 Embodiment Matrix O E and matrix L P

[0125]

[0126] (3) In the.inp file of Abaqus software, input the three-dimensional space routing coordinate matrix N and assign a node number to each coordinate. At this time, the generated pipeline node set is A Aba , the underground coordinate set B of the entire pipeline Aba . The starting coordinate selected in this embodiment is 1001, and the finally constructed set is

[0127] *NODE

[0128] ** Pipeline node set A Aba

[0129] 1001,0,0,0

[0130] 1121,-58.8497241700000,-104.196761200000,-0.897504577000000

[0131] 1141,-59.1768479200000,-104.775952300000,-0.913387590000000

[0132] 1529,-249.349664671974,-441.487667188803,-16.4851802118246

[0133] 1549,-250.167973919311,-442.363591454528,-16.5062818232976

[0134] 1617,-306.121905400000,-479.207762900000,-16.1024598900000

[0135] 1637,-306.803237300000,-479.656401800000,-16.0811559800000

[0136] 1693,-352.661221300000,-509.852664000000,-13.5431787500000

[0137] 1713,-353.802780000000,-511.972367400000,-13.4533934400000

[0138] 1830,-353.802780000000,-627.834080000000,-11.2000000000000

[0139] 1916,-353.802780000000,-713.794350000000,-9.23000000000000

[0140] 1955,-353.802780000000,-751.079821500000,-8.24572592100000

[0141] 1975,-354.454710800000,-752.778100600000,-8.18077069200000

[0142] 2055,-407.160283600000,-811.289971500000,-5.00926334400000

[0143] 2075,-407.812780000000,-812.989998800000,-4.95874105100000

[0144] 2204,-407.812780000000,-939.290072500000,-3.50124312400000

[0145] 2224,-408.464404600000,-940.988704800000,-3.48378804600000

[0146] 2301, -459.018617500000, -997.185457300000, -3.00185343500000

[0147] 2321, -459.407418400000, -997.617653700000, -3.00646361900000

[0148] 2617, -657.285892200000, -1217.58204800000, -9.58646985500000

[0149] 2637, -657.850444400000, -1218.62178600000, -9.61945021500000

[0150] 2741, -684.442740000000, -1317.70112000000, -12.9000000000000

[0151] 2801, -353.802780000000, -713.794350000000, -9.23000000000000

[0152] 2911, -463.802780000000, -713.794350000000, -9.23000000000000

[0153] **Underground Coordinate Set B Aba

[0154] 3001, 0, 0, -15

[0155] 3121, -58.8497241700000, -104.196761200000, -15.8975045800000

[0156] 3141, -59.1768479200000, -104.775952300000, -15.9133875900000

[0157] 3529, -249.349664671974, -441.487667188803, -31.4851802118246

[0158] 3549,-250.167973919311,-442.363591454528,-31.5062818232976

[0159] 3617,-306.121905400000,-479.207762900000,-31.1024598900000

[0160] 3637,-306.803237300000,-479.656401800000,-31.0811559800000

[0161] 3693,-352.661221300000,-509.852664000000,-28.5431787500000

[0162] 3713,-353.802780000000,-511.972367400000,-28.4533934400000

[0163] 3830,-353.802780000000,-627.834080000000,-26.2000000000000

[0164] 3916,-353.802780000000,-713.794350000000,-24.2300000000000

[0165] 3955,-353.802780000000,-751.079821500000,-23.2457259200000

[0166] 3975,-354.454710800000,-752.778100600000,-23.1807706900000

[0167] 4055,-407.160283600000,-811.289971500000,-20.0092633400000

[0168] 4075,-407.812780000000,-812.989998800000,-19.9587410500000

[0169] 4204,-407.812780000000,-939.290072500000,-18.5012431200000

[0170] 4224,-408.464404600000,-940.988704800000,-18.4837880500000

[0171] 4301,-459.018617500000,-997.185457300000,-18.0018534300000

[0172] 4321,-459.407418400000,-997.617653700000,-18.0064636200000

[0173] 4617,-657.285892200000,-1217.58204800000,-24.5864698600000

[0174] 4637,-657.850444400000,-1218.62178600000,-24.6194502100000

[0175] 4741,-684.442740000000,-1317.70112000000,-27.9000000000000

[0176] 4801,-353.802780000000,-713.794350000000,-24.2300000000000

[0177] 4911,-463.802780000000,-713.794350000000,-24.2300000000000

[0178] **Bend center coordinate set OA Aba

[0179] 7001,-58.7747797000000,-104.064066900000,-21.2169331000000

[0180] 7002,-251.556667167398,-440.251865266877,-16.2538069312641

[0181] 7003,-306.019599300000,-479.140423000000,4.21717098200000

[0182] 7004, -351.265074000000, -511.974466100000, -13.5613006500000

[0183] 7005, -356.341571600000, -751.077754200000, -8.16741422000000

[0184] 7006, -405.275623700000, -812.991385300000, -5.07889183300000

[0185] 7007, -410.352766200000, -939.290169100000, -3.50961114300000

[0186] 7008, -459.105279600000, -997.281754300000, -23.3214404500000

[0187] 7009, -655.397209200000, -1219.27905800000, -9.65452914100000

[0188] **Underground center coordinate set OB Aba

[0189] 8001, -58.7747797000000, -104.064066900000, -36.2169331000000

[0190] 8002, -251.556667167398, -440.251865266877, -31.2538069312641

[0191] 8003, -306.019599300000, -479.140423000000, -10.7828290200000

[0192] 8004, -351.265074000000, -511.974466100000, -28.5613006500000

[0193] 8005, -356.341571600000, -751.077754200000, -23.1674142200000

[0194] 8006, -405.275623700000, -812.991385300000, -20.0788918300000

[0195] 8007, -410.352766200000, -939.290169100000, -18.5096111400000

[0196] 8008, -459.105279600000, -997.281754300000, -38.3214404500000

[0197] 8009, -655.397209200000, -1219.27905800000, -24.6545291400000

[0198] (4) Generate the straight pipe node set of the pipeline:

[0199] *NGEN, NSET = NS1

[0200] 1001, 1121, 1

[0201] (5) Generate the elbow pipe node set of the pipeline:

[0202] *NGEN, LINE = C, NSET = NE1

[0203] 1121, 1141, 1, 7001

[0204] (6) Generate the surface node set:

[0205] *NGEN, NSET = NBS

[0206] 3001, 3121, 1

[0207] *NGEN, LINE = C, NSET = NBE1

[0208] 3121, 3141, 1, 8001

[0209] (7) Set the node set according to the type of settlement load to be applied,

[0210] ** Generation of settlement node group

[0211] *NSET, NSET = SUBPOINT1

[0212] 4199,4296,4200,4297,4201,4298,4202,4299,4225,4322,4226,4323,4227,4324,4228,4325,4229,4326

[0213] (8) Set the boundary condition node set:

[0214] *NSET,NSET=BC

[0215] 2911,1001,2741

[0216] (9) Generate pipe elements, including pipe elements for straight pipe sections and elbow elements for bent pipe sections:

[0217] *ELEMENT,TYPE=ELBOW31,ELSET=PIPES1

[0218] 1001,1001,1002

[0219] *ELGEN,ELSET=PIPES1

[0220] 1001,120,1

[0221] (10) Define the pipe cross-section type:

[0222] *BEAMSECTION,SECTION=ELBOW,ELSET=PIPES1,MATERIAL=STEEL

[0223] 0.254,0.007719,0

[0224] -25.991962,-46.020237,-15.396398

[0225] 3,20,6

[0226] (11) Define the pipe-soil interaction element:

[0227] *ELEMENT,TYPE=PSI34,ELSET=SOIL1

[0228] 3001,1001,1002,3002,3001

[0229] (12) Define the material properties of the pipe:

[0230] *MATERIAL,NAME=STEEL

[0231] *ELASTIC

[0232] 2.10E11, 0.3

[0233] *Expansion

[0234] 1.16e-05

[0235] (13) Define the material properties of the pipe-soil interaction:

[0236] *PIPE-SOIL INTERACTION, ELSET = SOIL1

[0237] *PIPE-SOIL STIFFNESS, TYPE = NONLINEAR, DIR = AXIAL

[0238] -4009.70000000000, -0.00400000000000000

[0239] 0, 0

[0240] 4009.70000000000, 0.00400000000000000

[0241] *PIPE-SOIL STIFFNESS, TYPE = NONLINEAR, DIR = VERTICAL

[0242] -74140, -0.0339000000000000

[0243] 0, 0

[0244] 8477.60000000000, 0.0153000000000000

[0245] *PIPE-SOIL STIFFNESS, TYPE = NONLINEAR, DIR = HORIZONTAL

[0246] -34227.4000000000, -0.0154000000000000

[0247] 0, 0[[ID=ABBR]]

[0248] (14) Define the initial temperature field and initial boundary conditions:

[0249] (14) Define the initial temperature field and initial boundary conditions:

[0250] *Initial Conditions, type = TEMPERATURE

[0251] NPIPE, 21.8

[0252] *BOUNDARY

[0253] BC,1,1

[0254] BC,2,2

[0255] BC,3,3

[0256] BC,4,4

[0257] BC,5,5

[0258] BC,6,6

[0259] (15) Define the internal pressure load, temperature load, and settlement load of the pipeline:

[0260] *STEP,NLGEOM

[0261] *static

[0262] 0.001,1.0,0.0000000001,0.15

[0263] *Dload

[0264] PIPEALL,PI,7.9e+06,0.48546

[0265] *Temperature

[0266] NPIPE,90

[0267] *BOUNDARY

[0268] SUBPOINT1,3,3,-0.05

[0269] (16) Write the mechanical parameters for the solution:

[0270] *ELEMENTOUTPUT, ELSET=PIPEALL

[0271] S

[0272] *ELEMENTOUTPUT, ELSET=PIPEALL

[0273] SF

[0274] *NODEOUTPUT, NSET=OUT

[0275] U

[0276] *ELPRINT, ELSET=PIPEALL, FREQUENCY=1

[0277] S

[0278] *ENDSTEP

[0279] After the submission calculation is completed, obtain the full-line stress analysis results calculated by the Abaqus software. As Figure 2 shown, extract the stress levels of the full-line route as Figure 3 shown

[0280] The above has made a detailed description of the implementation mode of the present invention in combination with the accompanying drawings and specific implementation modes. However, the present invention is not limited to the described implementation modes. For those of ordinary skill in the art, within the scope of the principles and technical ideas of the present invention, various changes, modifications, substitutions, and deformations of these implementation modes still fall within the protection scope of the present invention.

Claims

1. A method for stress analysis of the entire pipeline, characterized in that During the service process of long-distance pipelines, they are often subjected to additional axial stresses induced by temperature differences and additional stresses induced by surface settlement loads. These additional stresses will increase the stress level of the entire long-distance pipeline and increase the possibility of pipeline failure. A full-line stress analysis method based on Abaqus finite element software is proposed for pipeline stress acquisition, including the following steps: (1) Obtain the basic parameters of the entire pipeline; (2) Solve the required indirect parameters according to the basic parameters; (3) Write the.inp file required for the analysis of Abaqus finite element software; (4) Submit the.inp file to the Abaqus solver to obtain the full-line stress analysis results of the pipeline.

2. The type of load that causes an increase in the stress throughout the pipeline as described in claim 1, characterized in that, (including temperature difference load and surface settlement load.) 3. The basic parameters of the entire pipeline described in claim 1, characterized in that, (mainly including: The three-dimensional spatial routing coordinate matrix N for the entire pipeline, the routing coordinate matrix N for the straight pipe section P , the routing coordinate matrix N for the elbow section E , the surface elevation matrix Z for the entire pipeline G , the radius of curvature matrix R at each elbow E , the elastic modulus E and Poisson's ratio ν of the pipeline material, the pipeline diameter D, the pipeline wall thickness t, the thermal expansion coefficient α, the initial temperature T1, the changed temperature T2, the ground settlement u, the internal pressure P during pipeline operation, the three-dimensional soil spring stiffness matrix T around the pipeline u 、ΔT、P u 、ΔP、Q u 、ΔQ u 、Q d 、ΔQ d .

4. Solving the required indirect parameters according to the basic parameters as described in claim 1, characterized in that, (including: The center coordinate matrix O of the curvature radius of the elbow section E , matrix N P The distance matrix L between the i-th and (i + 1)-th coordinate positions P . The calculation method is shown in Formula 1. where x i is the x-axis coordinate at the i-th position of the coordinate matrix N, and y i is the y-axis coordinate at the i-th position of the coordinate matrix N, and z i is the z-axis coordinate at the i-th position of the coordinate matrix N.

5. The full-line stress analysis method based on Abaqus finite element software according to claim 1, characterized in that (Write the unique.inp file for Abaqus solution calculation according to the specific implementation in the specification, and then solve the full-line stress level of the pipeline to the Abaqus solver.)

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