Mechanical response analysis method and system of existing pipelines based on large deformation theory

Abstract

The present invention discloses a method and system for analyzing the mechanical response of an existing pipeline based on large deformation theory, and relates to the field of civil engineering. The present invention can obtain the contact state between the existing pipeline and the underlying soil layer by comparing the initial displacement vector of the existing pipeline with the amount of settlement of the underlying soil in the area where the existing pipeline is located. If the initial displacement vector of the existing pipeline is less than the corresponding amount of settlement of the underlying soil, it means that the underlying soil layer is separated from the existing pipeline, and the mechanical response of the existing pipeline is analyzed by the soil-structure separation model; otherwise, it means that the underlying soil layer is in contact with the existing pipeline, and the mechanical response of the existing pipeline is analyzed by the soil-structure contact model. Compared with the prior art, the present invention can clearly determine whether the underlying soil layer and the existing pipeline are in a contact state or a separation state, and thus can accurately calculate the mechanical response of the existing pipeline.

Description

Technical Field

[0001] The present invention relates to the field of civil engineering, and in particular to a method and system for analyzing mechanical responses of existing pipelines based on large deformation theory. Background Art

[0002] In recent decades, tunnel construction has been significantly developed in the field of urban underground space due to the increasing demand for tunnel construction and technological advances. However, the ground deformation caused by tunnel construction inevitably affects the existing underground infrastructure, such as existing tunnels, stations and pipelines. Therefore, it is necessary to analyze and predict the mechanical response of existing pipelines to ensure their safety and applicability before and after tunnel construction. However, in the prior art, the empirical formula of stratum deformation caused by tunnel excavation is often used to predict the deformation of existing pipelines, but this method cannot determine whether the underlying soil layer and the existing pipeline are in contact or separation, and thus cannot accurately calculate the mechanical response of the existing pipeline. Summary of the invention

[0003] The purpose of the present invention is to provide a method and system for analyzing the mechanical response of an existing pipeline based on large deformation theory. The present invention can accurately calculate the mechanical response of an existing pipeline.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for analyzing the mechanical response of an existing pipeline based on large deformation theory, the method comprising the following steps:

[0006] Acquiring engineering parameters, the engineering parameters including: geometric parameters of the target pipeline and geotechnical parameters of the area where the target pipeline is located;

[0007] Calculating pipeline deformation related parameters according to the engineering parameters, the pipeline deformation related parameters include pipeline self related parameters and pipeline environment related parameters, the pipeline self related parameters include the stiffness matrix of the existing pipeline end moment and the stiffness matrix of the existing pipeline axial force, the pipeline environment related parameters include the stiffness matrix of the roadbed reaction coefficient, the stress vector caused by the settlement of the overlying soil above the existing pipeline, and the displacement vector of the soil below the existing pipeline;

[0008] Substituting the pipeline deformation related parameters into a soil-structure contact model to calculate an initial displacement vector of the existing pipeline, wherein the soil-structure contact model is a function of the pipeline deformation related parameters and the displacement vector of the existing pipeline;

[0009] Calculate the settlement of the underlying soil in the area where the existing pipeline is located according to the engineering parameters;

[0010] Determine whether the initial displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a first determination result;

[0011] If the first judgment result is no, updating the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline-related parameters;

[0012] Substituting the updated first pipeline self-related parameters and the pipeline environment-related parameters into the soil-structure contact model to calculate the displacement vector of the first existing pipeline;

[0013] Determine whether a difference between the displacement vector of the first existing pipeline and the initial displacement vector of the existing pipeline is less than a first preset threshold, and obtain a second determination result;

[0014] If the second judgment result is no, the displacement vector of the first existing pipeline is used as the initial displacement vector of the existing pipeline, and the process returns to the step of "updating the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline's own related parameters";

[0015] If the second judgment result is yes, outputting the displacement vector of the first existing pipeline;

[0016] If the first judgment result is yes, a criterion matrix is ​​set, wherein the criterion items in the criterion matrix correspond to the magnitude relationship between the displacement vector of the existing pipeline and the settlement of the underlying soil in the area where the existing pipeline is located, and the criterion item where the displacement vector of the existing pipeline is smaller than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as 0;

[0017] Update the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline's own related parameters;

[0018] Substituting the updated second pipeline self-related parameters, the pipeline environment-related parameters and the criterion matrix into the soil-structure separation model to calculate the displacement vector of the second existing pipeline, wherein the soil-structure separation model is a function of the pipeline deformation-related parameters, the criterion matrix and the displacement vector of the existing pipeline;

[0019] Determine whether the displacement vector of the second existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a third determination result;

[0020] If the third judgment result is no, the judgment item is recorded as 1, and the process returns to the step of "updating the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline-related parameters".

[0021] If the third judgment result is yes, then judging whether the difference between the displacement vector of the second existing pipeline and the initial displacement vector of the existing pipeline is less than a second preset threshold value, and obtaining a fourth judgment result;

[0022] If the fourth judgment result is no, the displacement vector of the second existing pipeline is used as the initial displacement vector of the existing pipeline, and the process returns to the step of "updating the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline's own related parameters";

[0023] If the fourth determination result is yes, the displacement vector of the second existing pipeline is output.

[0024] Optionally, the existing pipeline mechanical response analysis method based on large deformation theory also includes:

[0025] When the second judgment result is yes, the internal force is calculated according to the displacement vector of the first existing pipeline, and the internal force is output.

[0026] Optionally, the calculation formula of the internal force is:

[0027] p=k(w(x)-s 2 (x))H

[0028] Among them, p is the internal force, k is the roadbed reaction coefficient, w(x) is the displacement vector corresponding to each pipeline unit, s 2 (x) is the settlement of the underlying soil corresponding to the area where each pipeline unit is located, H is the criterion item corresponding to each pipeline unit,

[0029] Optionally, the existing pipeline mechanical response analysis method based on large deformation theory also includes:

[0030] When the first judgment result is yes, the pipeline unit whose displacement vector of the existing pipeline is smaller than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as a separation node, and the pipeline unit is a unit obtained by dividing the existing pipeline into equal lengths;

[0031] determining the length of the soil gap according to the number of separation nodes;

[0032] Determine the height of the soil gap corresponding to each separation node according to the difference between the displacement vector corresponding to each separation node and the settlement of the underlying soil;

[0033] The length of the soil gap and the height of the soil gap are output.

[0034] Optionally, the soil-structure contact model is:

[0035] ([M]-[N]+[K]){w}={q 1}+{K}{S 2}

[0036] Wherein, [M] is the stiffness matrix of the moment at the end of the existing pipeline, [N] is the stiffness matrix of the axial force of the existing pipeline, [K] is the stiffness matrix of the roadbed reaction coefficient, {w} is the displacement vector of the existing pipeline, {q 1} is the stress vector caused by the settlement of the overlying soil above the existing pipeline, {S 2} is the displacement vector of the soil under the existing pipeline.

[0037] Optionally, the following formula is used to update the pipeline's own related parameters:

[0038]

[0039]

[0040]

[0041] Wherein, g is the ratio of the deformed length of the existing pipeline to the initial length, h is the proportional parameter, w is the displacement vector of the existing pipeline, w' is the derivative of the displacement vector of the existing pipeline, x is the horizontal component of the ground deformation caused by the tunnel, [M] is the stiffness matrix of the moment at the end of the existing pipeline, E is the elastic modulus of the existing pipeline, I is the section moment of inertia, l is the length of the existing pipeline, and g n is the ratio of the deformed length of the existing pipeline to the initial length in the nth pipeline unit, n is the nth pipeline unit, and [N] is the stiffness matrix of the axial force of the existing pipeline.

[0042] Optionally, the soil-structure separation model is:

[0043] ([M]-[N]+[K][H]){w}={q 1}+{K}[H]{S 2}

[0044] Wherein, [M] is the stiffness matrix of the moment at the end of the existing pipeline, [N] is the stiffness matrix of the axial force of the existing pipeline, [K] is the stiffness matrix of the roadbed reaction coefficient, {w} is the displacement vector of the existing pipeline, {q 1} is the stress vector caused by the settlement of the overlying soil above the existing pipeline, {S 2} is the displacement vector of the soil under the existing pipeline, and [H] is the criterion matrix.

[0045] Optionally, the calculation formula for the underlying soil settlement is:

[0046]

[0047] Among them, S 2 (x) is the settlement of the underlying soil, is the maximum settlement of the underlying soil, x is the horizontal component of the ground deformation caused by the tunnel, and i is the horizontal distance from the center line of the tunnel to the inflection point of the settlement trough.

[0048] The present invention also provides an existing pipeline mechanical response analysis system based on large deformation theory, and the existing pipeline mechanical response analysis system based on large deformation theory includes:

[0049] An engineering parameter acquisition unit, used to acquire engineering parameters, the engineering parameters including: geometric parameters of the target pipeline and geotechnical parameters of the area where the target pipeline is located;

[0050] A first calculation unit is used to calculate pipeline deformation related parameters according to the engineering parameters, wherein the pipeline deformation related parameters include pipeline self related parameters and pipeline environment related parameters, wherein the pipeline self related parameters include the stiffness matrix of the existing pipeline end moment and the stiffness matrix of the existing pipeline axial force, and the pipeline environment related parameters include the stiffness matrix of the roadbed reaction coefficient, the stress vector caused by the settlement of the overlying soil above the existing pipeline, and the displacement vector of the soil below the existing pipeline;

[0051] A second calculation unit is used to substitute the pipeline deformation related parameters into a soil-structure contact model to calculate an initial displacement vector of the existing pipeline, wherein the soil-structure contact model is a function of the pipeline deformation related parameters and the displacement vector of the existing pipeline;

[0052] A third calculation unit is used to calculate the settlement of the underlying soil in the area where the existing pipeline is located according to the engineering parameters;

[0053] A first judgment unit is used to judge whether the initial displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a first judgment result;

[0054] A first parameter updating unit, configured to update the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline-related parameters when the first judgment result is no;

[0055] A fourth calculation unit is used to substitute the updated first pipeline self-related parameters and the pipeline environment-related parameters into the soil-structure contact model to calculate the displacement vector of the first existing pipeline;

[0056] A second judgment unit is used to judge whether the difference between the displacement vector of the first existing pipeline and the initial displacement vector of the existing pipeline is less than a first preset threshold value, and obtain a second judgment result;

[0057] A first returning unit, configured to use the displacement vector of the first existing pipeline as the initial displacement vector of the existing pipeline and return the first parameter updating unit when the second judgment result is no;

[0058] A first output unit, configured to output a displacement vector of the first existing pipeline when the second judgment result is yes;

[0059] A criterion matrix setting unit, used for setting a criterion matrix when the first judgment result is yes, wherein the criterion items in the criterion matrix correspond to the magnitude relationship between the displacement vector of the existing pipeline and the settlement of the underlying soil in the area where the existing pipeline is located, and the criterion item where the displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as 0;

[0060] A second parameter updating unit, configured to update the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline-related parameters;

[0061] a fifth calculation unit, for substituting the updated second pipeline self-related parameters, the pipeline environment-related parameters and the criterion matrix into a soil-structure separation model to calculate a displacement vector of a second existing pipeline, wherein the soil-structure separation model is a function of pipeline deformation-related parameters, the criterion matrix and the displacement vector of the existing pipeline;

[0062] A third judgment unit is used to judge whether the displacement vector of the second existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a third judgment result;

[0063] A second returning unit, configured to, when the third judgment result is no, record the criterion item as 1 and return to the first parameter updating unit;

[0064] a fourth judgment unit, configured to judge whether a difference between the displacement vector of the second existing pipeline and the initial displacement vector of the existing pipeline is less than a second preset threshold value when the third judgment result is yes, to obtain a fourth judgment result;

[0065] a third returning unit, configured to use the displacement vector of the second existing pipeline as the initial displacement vector of the existing pipeline and return the result to the second parameter updating unit when the fourth judgment result is no;

[0066] The second output unit is configured to output the displacement vector of the second existing pipeline when the fourth judgment result is yes.

[0067] Optionally, the existing pipeline mechanical response analysis system based on large deformation theory also includes:

[0068] An internal force calculation and output unit is used to calculate the internal force according to the displacement vector of the first existing pipeline and output the internal force when the second judgment result is yes.

[0069] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0070] The present invention provides a method and system for analyzing the mechanical response of an existing pipeline based on the large deformation theory. The present invention first calculates pipeline deformation-related parameters according to engineering parameters, substitutes the pipeline deformation-related parameters into a soil-structure contact model to calculate the initial displacement vector of the existing pipeline, calculates the settlement of the underlying soil in the area where the existing pipeline is located according to the engineering parameters, and then compares the initial displacement vector of the existing pipeline with the settlement of the underlying soil in the area where the existing pipeline is located to know the contact state between the existing pipeline and the underlying soil layer. If the initial displacement vector of the existing pipeline is less than the corresponding settlement of the underlying soil, it means that the underlying soil layer is separated from the existing pipeline, and the mechanical response of the existing pipeline is analyzed by the soil-structure separation model; otherwise, it means that the underlying soil layer is in contact with the existing pipeline, and the mechanical response of the existing pipeline is analyzed by the soil-structure contact model. Compared with the prior art, the present invention can clearly determine whether the underlying soil layer and the existing pipeline are in a contact state or a separation state, and thus can accurately calculate the mechanical response of the existing pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0072] Figure 1 A flowchart of a method for analyzing mechanical response of an existing pipeline based on large deformation theory provided in Example 1 of the present invention;

[0073] Figure 2a is the spatial curve diagram of the thin curved rod;

[0074] Figure 2b is a graphical representation of the microelement ds;

[0075] Figure 3a It is a graphical representation of pipeline deformation;

[0076] Figure 3b It is a graphical representation of the axial and vertical displacements of the microelement ds;

[0077] Figure 4 Schematic diagram of the load patterns for soil-structure contact model and soil-structure separation model;

[0078] Figure 5 A structural block diagram of an existing pipeline mechanical response analysis system based on large deformation theory provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0079] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] The purpose of the present invention is to provide a method and system for analyzing the mechanical response of an existing pipeline based on large deformation theory. The present invention can accurately calculate the mechanical response of an existing pipeline.

[0081] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0082] Embodiment 1:

[0083] The calculation model of existing pipelines based on large deformation theory is proposed based on the following basic assumptions:

[0084] (1) The existing pipeline is regarded as an Euler-Bernoulli beam, which conforms to the plane section assumption;

[0085] (2) The interaction between soil and existing pipelines is modeled using Winkler foundation modeling;

[0086] (3) The horizontal resistance of the soil acts on the existing pipeline and cannot be ignored;

[0087] (4) The existing pipeline is axially elastic, homogeneous, and isotropic;

[0088] (5) The axial displacement is proportional to the vertical displacement of the soil at the same position. The ratio of the axial displacement to the vertical displacement of the existing pipeline is consistent with the ratio of the soil displacement;

[0089] (6) The deformation of the existing pipeline is smaller than that of the underlying soil layer, thus forming a gap in the soil. On the contrary, the pipeline remains in contact with the soil.

[0090] Based on the basic assumptions, the large deformation theory is used to calculate the mechanical response of the existing pipeline. The equilibrium equations, geometric equations, physical equations and control equations involved are written as follows:

[0091] Balanced equation:

[0092] Figure 2aA thin curved rod is shown deforming along a curve C in three-dimensional space. The rod has a displacement vector at time t. The parameter s (arc length) is chosen as the natural coordinate. When C moves, the position of any point on the curve C can be obtained by formula (1) in the Cartesian coordinate system.

[0093]

[0094] Among them, s is the independent variable of x, y, z functions respectively, and x, y, z are functions of s.

[0095] The displacement vector of any point on the curve C relative to the origin O can be expressed as:

[0096] r=r(s,t) (2)

[0097] Take out a microelement ds on curve C for force analysis, such as Figure 2b As shown in Figure 2, it is assumed that the external force of the microelement ds consists of the end force F, the end moment M, the external force q acting on the existing pipeline, and the distributed moment m. The end force consists of the axial force N and the shear force Q.

[0098] By performing force analysis, we can obtain the momentum D and angular momentum L of the microelement ds:

[0099]

[0100]

[0101] Where γ is the mass of the rod per unit length, r is the displacement vector of the center of mass of ds, and × is the vector product.

[0102] According to the momentum theorem, the change in momentum is equal to the impulse of the force:

[0103] D=(F+qds)dt (5)

[0104] Where q is the external force acting on the existing pipeline.

[0105] Substituting equation (3) into equation (5), we get a new equation:

[0106]

[0107] In addition, another equation can be given based on the angular momentum principle:

[0108]

[0109] The vector in the above equation can be expressed using the coordinate components of the x, y, and z axes as follows:

[0110]

[0111]

[0112] Among them, γ is the mass of the rod per unit length, a is the acceleration, g is the ratio of the deformation length of the existing pipeline to the initial length, g=ε+1, ρ is the radius of curvature, and τ is the deflection radius.

[0113]

[0114]

[0115]

[0116] Assume that the curve moves in the xy plane and maintains static equilibrium. Ignore the effects of time t and body torque. Parameters can be simplified. 1 / τ=0,M x =M y =0,m x =m y =m z =0, F x =0,q x =0,a x =a y = 0. The subscripts x, y and z are the components of the parameter in the x, y and z directions respectively. Therefore, the equilibrium equation of the existing pipeline can be rewritten by equations (8) and (9).

[0117]

[0118] Where M is the end moment, Q is the shear force, and N is the axial force; q x is the horizontal resistance acting on the existing pipeline, q y is the vertical resistance acting on the existing pipeline, g is the ratio of the deformed length of the existing pipeline to the initial length, and ρ is the radius of curvature.

[0119] Physics equation:

[0120] The relationship between the five unknowns (M, Q, N, g, ρ) in equation (13) is obtained by using two physical equations (16) and (17). Assume that the initial length of the unit is b and the deformation length is b′. We use the parameter g to describe the axial deformation of the existing pipeline. g is the ratio of the deformation length of the existing pipeline to the initial length:

[0121]

[0122] The relationship between strain ε and g is expressed as:

[0123]

[0124] According to Hooke's law, the axial force is expressed as:

[0125] N=A·σ=A·E·ε=EA(g-1) (16)

[0126] Where A is the cross-sectional area of ​​the pipeline and E is the elastic modulus of the pipeline.

[0127] Based on the definition of end moment, the relationship between the end moment M and the curvature radius ρ can be expressed as:

[0128]

[0129] Where I is the moment of inertia of the section, ρ 0 , ρ are the curvature radii of the pipeline before and after deformation.

[0130] Geometric equations:

[0131] If the deformed pipeline is regarded as a curve in a plane, a geometric equation can be obtained based on the definition of curvature.

[0132]

[0133] Among them, θ is the rotation angle, and ω is the displacement vector of the existing pipeline.

[0134] Since the undeformed pipeline is a straight line, the initial curvature radius is 1 / ρ 0 is zero.

[0135] Formula (17) can be rewritten as:

[0136]

[0137] The shear force Q is expressed as:

[0138]

[0139] Governing equations:

[0140] According to the equilibrium equation, geometric equation and physical equation, the control equation of the existing pipeline based on the large deformation theory can be obtained:

[0141]

[0142] Among them, q x is the horizontal resistance acting on the existing pipeline, q y It is the vertical resistance acting on the existing pipeline.

[0143] The existing pipeline is regarded as an infinitely long beam, and the two ends of the beam (x = ±L) are sliding supports. Therefore, the rotation angle and shear force at both ends of the beam are zero:

[0144]

[0145]

[0146] Since existing pipelines have different deformation mechanisms and load modes, the present invention provides two different calculation programs, which are respectively used for soil-structure contact model and soil-structure separation model. Figure 3a and Figure 3b The deformation mechanism of the existing pipeline is given according to the large deformation theory. The existing pipeline produces vertical displacement and axial displacement in the vertical plane. The geometric relationship is obtained by taking out the microelement ds. That is:

[0147] (ds') 2 =(dw) 2 +(du) 2 (twenty four)

[0148] Assume that Z is the horizontal displacement of the existing pipeline. Z and its first-order derivative can be expressed as:

[0149]

[0150] Based on equations (14) and (24), the parameter g can be rewritten as:

[0151]

[0152] In addition, the relationship between the horizontal and vertical components of the ground deformation caused by the tunnel is:

[0153]

[0154] Where x is the horizontal component of ground deformation caused by the tunnel, z is the vertical component of ground deformation caused by the tunnel, S max is the maximum settlement value, and i is the horizontal distance from the tunnel centerline to the inflection point of the settlement trough.

[0155] According to basic assumption (5), the relationship between the horizontal displacement and vertical displacement of the existing pipeline can also be described by the following formula:

[0156]

[0157] Where h is a proportional parameter, which is convenient for problem simplification. h can be regarded as the cover depth of the existing pipeline. When h tends to infinity, Z is equal to zero. Based on equations (26) and (28), g can be rewritten as:

[0158]

[0159] also, Figure 4 The load pattern of the existing pipeline is given, including the loading pressure of the overlying soil, the vertical roadbed reaction force of the underlying soil, and the horizontal resistance acting axially on the existing pipeline.

[0160] If the underlying soil settlement S2 If (x) is greater than w(x), the bottom of the existing pipeline will be separated from the underlying soil layer. The foundation spring is not compressed and the internal force p is equal to 0. On the contrary, the foundation spring will be compressed, generating an internal force p. Therefore, the internal force p can be given by formula (30):

[0161]

[0162] Among them, p is the internal force, k is the roadbed reaction coefficient, w(x) is the displacement vector corresponding to each pipeline unit, s 2 (x) is the settlement of the underlying soil corresponding to the area where each pipeline unit is located, H is the criterion item corresponding to each pipeline unit,

[0163] The settlement of the underlying soil and the settlement of the overlying soil can be described by the Peck formula:

[0164]

[0165]

[0166] Among them, S 1 (x) is the settlement of the overlying soil, S 2 (x) is the settlement of the underlying soil, is the maximum settlement of the overlying soil, is the maximum settlement of the underlying soil, x is the horizontal component of the ground deformation caused by the tunnel, and i is the horizontal distance from the center line of the tunnel to the inflection point of the settlement trough.

[0167] When the underlying soil layer is in contact with the existing pipeline, the soil-structure contact model is used to analyze the mechanical response of the existing pipeline. The finite difference method is used to obtain the numerical solution of the control equation (21). Through MATLAB programming, the Euler-Bernoulli existing pipeline can be divided into n+5 units of length l, and 4 virtual units are located at both ends of the existing pipeline. The second equation of equation (21) can be rewritten in finite difference form:

[0168]

[0169] Wherein, l is the length of the existing pipeline, and i is the position of the i-th pipeline unit.

[0170] According to the boundary conditions (22) and (23), the rotation angle and shear force at both ends of the existing pipeline are zero:

[0171]

[0172]

[0173] Among them, θ 0 is the angle of one end of the existing pipeline, θn is the size of the corner at the other end of the existing pipeline, Q 0 is the shear force at one end of the existing pipeline, Q n is the magnitude of the shear force at the other end of the existing pipeline.

[0174] Since the deformation at both ends of the existing pipeline is the smallest, the parameter g is considered to be 1 in equation (35). The four virtual nodes (w -2 , w -1 , w n+1 , w n+2 )’s displacement vector:

[0175]

[0176] Therefore, equation (33) can be rewritten in matrix-vector form:

[0177] ([M]-[N]+[K]){w}={q 1}+{K}{S 2} (37)

[0178] That is, the soil-structure contact model is shown in formula (37).

[0179] Wherein, [M] is the stiffness matrix of the moment at the end of the existing pipeline, [N] is the stiffness matrix of the axial force of the existing pipeline, [K] is the stiffness matrix of the roadbed reaction coefficient, {w} is the displacement vector of the existing pipeline, {q 1} is the stress vector caused by the settlement of the overlying soil above the existing pipeline, {S 2} is the displacement vector of the soil under the existing pipeline.

[0180]

[0181]

[0182]

[0183] According to formula (37), the displacement vector {w} of the existing pipeline can be solved.

[0184] The end moment, shear force and axial force can be expressed as:

[0185]

[0186]

[0187] N i =EA(g i -1) (43)

[0188] The subscripts 0 and n represent the two ends of the existing pipeline, and i represents the middle section of the existing pipeline.

[0189] Substituting the updated matrix and vectors [M], [N] into formula (37), the displacement vector of the existing pipeline can be solved.

[0190] When considering the possible formation of soil gaps under existing pipelines, we use the soil-structure separation model. Compared with the soil-structure contact model, the subgrade reacts differently.

[0191]

[0192] The Heaviside function is used to describe the foundation reaction in equation (30).

[0193] p=k(w(x)-s 2 (x))H (45)

[0194] Therefore, the second equation of (21) can be expressed in finite difference form as:

[0195]

[0196] Formula (46) can also be rewritten in matrix-vector form:

[0197] ([M]-[N]+[K][H]){w}={q 1}+{K}[H]{S 2} (47)

[0198] That is, the soil-structure separation model is shown in formula (47).

[0199] Wherein, [M] is the stiffness matrix of the moment at the end of the existing pipeline, [N] is the stiffness matrix of the axial force of the existing pipeline, [K] is the stiffness matrix of the roadbed reaction coefficient, {w} is the displacement vector of the existing pipeline, {q 1} is the stress vector caused by the settlement of the overlying soil above the existing pipeline, {S 2} is the displacement vector of the soil under the existing pipeline, [H] is the criterion matrix for the formation of soil gap {H 0 , H 1 , …H n}.

[0200] In specific applications, such as Figure 1 As shown, the present invention provides a method for analyzing the mechanical response of an existing pipeline based on large deformation theory, and the method for analyzing the mechanical response of an existing pipeline based on large deformation theory comprises the following steps:

[0201] S1: Acquire engineering parameters, where the engineering parameters include: geometric parameters of the target pipeline and geotechnical parameters of the area where the target pipeline is located;

[0202] S2: Calculate pipeline deformation related parameters according to the engineering parameters, the pipeline deformation related parameters include pipeline self-related parameters and pipeline environment related parameters, the pipeline self-related parameters include the stiffness matrix of the existing pipeline end moment and the stiffness matrix of the existing pipeline axial force, the pipeline environment related parameters include the stiffness matrix of the roadbed reaction coefficient, the stress vector caused by the settlement of the overlying soil above the existing pipeline and the displacement vector of the soil below the existing pipeline; that is, calculate [M] as shown in formula (38), [N] as shown in formula (39), [K] as shown in formula (40), and {q in formula (37) 1} and {S 2}.

[0203] S3: Substitute the pipeline deformation related parameters into the soil-structure contact model to calculate the initial displacement vector of the existing pipeline. The soil-structure contact model is a function of the pipeline deformation related parameters and the displacement vector of the existing pipeline; that is, the known parameters are substituted into formula (37) to calculate the initial displacement vector of the existing pipeline.

[0204] S4: Calculate the settlement of the underlying soil in the area where the existing pipeline is located according to the engineering parameters; that is, the settlement of the underlying soil in the area where the existing pipeline is located can be calculated according to formula (32).

[0205] S5: determining whether the initial displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtaining a first determination result;

[0206] S6: If the first judgment result is no, indicating that the underlying soil layer is in contact with the existing pipeline, the pipeline's own related parameters are updated according to the initial displacement vector of the existing pipeline to obtain the updated first pipeline's own related parameters; that is, g is updated according to formula (29), and then [M] in formula (38) and [N] in formula (39) are updated.

[0207] S7: Substitute the updated first pipeline's own related parameters and the pipeline environment related parameters into the soil-structure contact model to calculate the displacement vector of the first existing pipeline; that is, substitute the updated parameters back into formula (37) to calculate the displacement vector of the first existing pipeline.

[0208] S8: Determine whether the difference between the displacement vector of the first existing pipeline and the initial displacement vector of the existing pipeline is less than a first preset threshold, and obtain a second determination result;

[0209] S9: If the second judgment result is no, the displacement vector of the first existing pipeline is used as the initial displacement vector of the existing pipeline, and the process returns to the step of "updating the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline's own related parameters";

[0210] S10: If the second judgment result is yes, outputting the displacement vector of the first existing pipeline;

[0211] S11: If the first judgment result is yes, indicating that the underlying soil layer is separated from the existing pipeline, a criterion matrix is ​​set, wherein the criterion items in the criterion matrix correspond to the magnitude relationship between the displacement vector of the existing pipeline and the settlement of the underlying soil in the area where the existing pipeline is located, and the criterion item where the displacement vector of the existing pipeline is smaller than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as 0;

[0212] S12: Update the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline's own related parameters; similarly update g according to formula (29), and then update [M] in formula (38) and [N] in formula (39).

[0213] S13: Substitute the updated second pipeline's own related parameters, the pipeline environment related parameters and the criterion matrix into the soil-structure separation model to calculate the displacement vector of the second existing pipeline. The soil-structure separation model is a function of the pipeline deformation related parameters, the criterion matrix and the displacement vector of the existing pipeline; that is, substitute the updated parameters into formula (47) to calculate the displacement vector of the second existing pipeline.

[0214] S14: Determine whether the displacement vector of the second existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a third judgment result; the purpose of this judgment is to prevent the update of parameters, which causes the underlying soil layer and the existing pipeline to change from a separated state to a contact state.

[0215] S15: If the third judgment result is no, indicating that the underlying soil layer and the existing pipeline are in contact, the judgment item is recorded as 1, and the process returns to the step of "updating the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain the updated first pipeline-related parameters".

[0216] S16: If the third judgment result is yes, determine whether the difference between the displacement vector of the second existing pipeline and the initial displacement vector of the existing pipeline is less than a second preset threshold, and obtain a fourth judgment result;

[0217] S17: If the fourth judgment result is no, the displacement vector of the second existing pipeline is used as the initial displacement vector of the existing pipeline, and the process returns to the step of "updating the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline's own related parameters";

[0218] S18: If the fourth determination result is yes, outputting the displacement vector of the second existing pipeline.

[0219] It should be noted that the displacement vector of the existing pipeline includes the displacement vectors of multiple pipeline units; the underlying soil settlement includes the underlying soil settlement of the area where the multiple pipeline units are located, and the pipeline units are units obtained by dividing the existing pipeline into equal lengths; at the beginning, the criterion matrix [H] is used as the unit matrix. Assume that each node is in a contact state. Using the calculation process of the soil-structure contact model, the displacement vector {w} of the existing pipeline is obtained. The displacement vector corresponding to each pipeline unit in the displacement vector {w} of the existing pipeline is compared with the underlying soil settlement of the area where each pipeline unit in {S2} is located. If w i 2，i , then the contact node is converted into a separation node, and the corresponding criterion item H i is recorded as 0. If w i ≥S 2，i , then the nodes will still be in contact, and the corresponding criterion item H i =1. That is, when the criterion item is 0, it means that the underlying soil layer is separated from the existing pipeline, and the soil-structure separation model is used to calculate the mechanical response of the existing pipeline; when the criterion item is 1, it means that the underlying soil layer is in contact with the existing pipeline, and the soil-structure contact model is used to calculate the mechanical response of the existing pipeline. If the difference between the displacement vector of the first existing pipeline or the displacement vector of the second existing pipeline and the displacement vector of the initial existing pipeline is less than a specified constant (close to 0), the displacement vector of the existing pipeline can be obtained.

[0220] Specifically, the existing pipeline mechanical response analysis method based on large deformation theory also includes:

[0221] When the second judgment result is yes, the internal force is calculated according to the displacement vector of the first existing pipeline and the internal force is output. The calculation formula of the internal force is shown in formula (30).

[0222] In addition, the existing pipeline mechanical response analysis method based on large deformation theory also includes:

[0223] When the first judgment result is yes, the pipeline unit whose displacement vector of the existing pipeline is smaller than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as a separation node, and the pipeline unit is a unit obtained by dividing the existing pipeline into equal lengths; ​

[0224] determining the length of the soil gap according to the number of separation nodes;

[0225] Determine the height of the soil gap corresponding to each separation node according to the difference between the displacement vector corresponding to each separation node and the settlement of the underlying soil;

[0226] The length of the soil gap and the height of the soil gap are output.

[0227] In summary, the present invention can know the contact state between the existing pipeline and the underlying soil layer by comparing the displacement vector of the existing pipeline with the amount of settlement of the underlying soil in the area where the existing pipeline is located. If the displacement vector of the existing pipeline is smaller than the corresponding amount of settlement of the underlying soil, it means that the underlying soil layer is separated from the existing pipeline, and the mechanical response of the existing pipeline is analyzed by the soil-structure separation model; otherwise, it means that the underlying soil layer is in contact with the existing pipeline, and the mechanical response of the existing pipeline is analyzed by the soil-structure contact model. Compared with the prior art, the present invention can clearly determine whether the underlying soil layer and the existing pipeline are in a contact state or a separation state, and thus can accurately calculate the mechanical response of the existing pipeline.

[0228] Embodiment 2:

[0229] See also Figure 5 The present invention provides a mechanical response analysis system for existing pipelines based on large deformation theory, and the mechanical response analysis system for existing pipelines based on large deformation theory includes:

[0230] The engineering parameter acquisition unit 1 is used to acquire engineering parameters, wherein the engineering parameters include: geometric parameters of the target pipeline and geotechnical parameters of the area where the target pipeline is located;

[0231] A first calculation unit 2 is used to calculate pipeline deformation related parameters according to the engineering parameters, wherein the pipeline deformation related parameters include pipeline self-related parameters and pipeline environment related parameters, wherein the pipeline self-related parameters include the stiffness matrix of the existing pipeline end moment and the stiffness matrix of the existing pipeline axial force, and the pipeline environment related parameters include the stiffness matrix of the roadbed reaction coefficient, the stress vector caused by the settlement of the overlying soil above the existing pipeline, and the displacement vector of the soil below the existing pipeline;

[0232] A second calculation unit 3 is used to substitute the pipeline deformation related parameters into a soil-structure contact model to calculate an initial displacement vector of the existing pipeline, wherein the soil-structure contact model is a function of the pipeline deformation related parameters and the displacement vector of the existing pipeline;

[0233] A third calculation unit 4 is used to calculate the settlement of the underlying soil in the area where the existing pipeline is located according to the engineering parameters;

[0234] A first judgment unit 5 is used to judge whether the initial displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a first judgment result;

[0235] A first parameter updating unit 6 is used to update the pipeline related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline related parameters when the first judgment result is no;

[0236] A fourth calculation unit 7 is used to substitute the updated first pipeline self-related parameters and the pipeline environment-related parameters into the soil-structure contact model to calculate the displacement vector of the first existing pipeline;

[0237] A second judgment unit 8 is used to judge whether the difference between the displacement vector of the first existing pipeline and the initial displacement vector of the existing pipeline is less than a first preset threshold value, and obtain a second judgment result;

[0238] A first returning unit 9, configured to use the displacement vector of the first existing pipeline as the initial displacement vector of the existing pipeline and return the first parameter updating unit when the second judgment result is no;

[0239] A first output unit 10, configured to output a displacement vector of the first existing pipeline when the second judgment result is yes;

[0240] A criterion matrix setting unit 11 is used to set a criterion matrix when the first judgment result is yes, wherein the criterion items in the criterion matrix correspond to the magnitude relationship between the displacement vector of the existing pipeline and the settlement of the underlying soil in the area where the existing pipeline is located, and the criterion item where the displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as 0;

[0241] A second parameter updating unit 12 is used to update the pipeline related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline related parameters;

[0242] A fifth calculation unit 13 is used to substitute the updated second pipeline self-related parameters, the pipeline environment-related parameters and the criterion matrix into the soil-structure separation model to calculate the displacement vector of the second existing pipeline, wherein the soil-structure separation model is a function of the pipeline deformation-related parameters, the criterion matrix and the displacement vector of the existing pipeline;

[0243] The third judgment unit 14 is used to judge whether the displacement vector of the second existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a third judgment result;

[0244] A second returning unit 15, configured to, when the third judgment result is no, record the criterion item as 1 and return to the first parameter updating unit;

[0245] The fourth judgment unit 16 is used to judge whether the difference between the displacement vector of the second existing pipeline and the initial displacement vector of the existing pipeline is less than a second preset threshold value when the third judgment result is yes, so as to obtain a fourth judgment result;

[0246] A third returning unit 17, configured to use the displacement vector of the second existing pipeline as the initial displacement vector of the existing pipeline and return the result to the second parameter updating unit when the fourth judgment result is no;

[0247] The second output unit 18 is configured to output the displacement vector of the second existing pipeline when the fourth judgment result is yes.

[0248] Specifically, the existing pipeline mechanical response analysis system based on large deformation theory also includes:

[0249] The internal force calculation and output unit is used to calculate the internal force according to the displacement vector of the first existing pipeline and output the internal force when the second judgment result is yes. The calculation formula of the internal force is shown in formula (30).

[0250] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0251] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for analyzing the mechanical response of existing pipelines based on large deformation theory. It is characterized in that The following steps are involved: Acquiring engineering parameters, the engineering parameters including: geometric parameters of the target pipeline and geotechnical parameters of the area where the target pipeline is located; Calculating pipeline deformation related parameters according to the engineering parameters, the pipeline deformation related parameters include pipeline self related parameters and pipeline environment related parameters, the pipeline self related parameters include the stiffness matrix of the existing pipeline end moment and the stiffness matrix of the existing pipeline axial force, the pipeline environment related parameters include the stiffness matrix of the roadbed reaction coefficient, the stress vector caused by the settlement of the overlying soil above the existing pipeline, and the displacement vector of the soil below the existing pipeline; Substituting the pipeline deformation related parameters into a soil-structure contact model to calculate an initial displacement vector of the existing pipeline, wherein the soil-structure contact model is a function of the pipeline deformation related parameters and the displacement vector of the existing pipeline; Calculate the settlement of the underlying soil in the area where the existing pipeline is located according to the engineering parameters; Determine whether the initial displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a first determination result; If the first judgment result is no, updating the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline-related parameters; Substituting the updated first pipeline self-related parameters and the pipeline environment-related parameters into the soil-structure contact model to calculate the displacement vector of the first existing pipeline; Determine whether a difference between the displacement vector of the first existing pipeline and the initial displacement vector of the existing pipeline is less than a first preset threshold, and obtain a second determination result; If the second judgment result is no, the displacement vector of the first existing pipeline is used as the initial displacement vector of the existing pipeline, and the process returns to the step of "updating the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline's own related parameters"; If the second judgment result is yes, outputting the displacement vector of the first existing pipeline; If the first judgment result is yes, a criterion matrix is ​​set, wherein the criterion items in the criterion matrix correspond to the magnitude relationship between the displacement vector of the existing pipeline and the settlement of the underlying soil in the area where the existing pipeline is located, and the criterion item where the displacement vector of the existing pipeline is smaller than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as 0; Update the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline's own related parameters; Substituting the updated second pipeline self-related parameters, the pipeline environment-related parameters and the criterion matrix into the soil-structure separation model to calculate the displacement vector of the second existing pipeline, wherein the soil-structure separation model is a function of the pipeline deformation-related parameters, the criterion matrix and the displacement vector of the existing pipeline; Determine whether the displacement vector of the second existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a third determination result; If the third judgment result is no, the criterion item is recorded as 1, and the process returns to step "update the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline-related parameters"; If the third judgment result is yes, then judging whether the difference between the displacement vector of the second existing pipeline and the initial displacement vector of the existing pipeline is less than a second preset threshold value, and obtaining a fourth judgment result; If the fourth judgment result is no, the displacement vector of the second existing pipeline is used as the initial displacement vector of the existing pipeline, and the process returns to the step of "updating the pipeline's own related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline's own related parameters"; If the fourth determination result is yes, the displacement vector of the second existing pipeline is output.

2. According to the method for analyzing the mechanical response of existing pipelines based on large deformation theory according to claim 1, It is characterized in that The existing pipeline mechanical response analysis method based on large deformation theory also includes: When the second judgment result is yes, the internal force is calculated according to the displacement vector of the first existing pipeline, and the internal force is output.

3. According to the method for analyzing the mechanical response of existing pipelines based on large deformation theory as described in claim 2, It is characterized in that The calculation formula of the internal force is: p=k(w(x)-s 2 (x))H Among them, p is the internal force, k is the roadbed reaction coefficient, w(x) is the displacement vector corresponding to each pipeline unit, s 2 (x) is the settlement of the underlying soil corresponding to the area where each pipeline unit is located, H is the criterion item corresponding to each pipeline unit, 4. According to the method for analyzing the mechanical response of existing pipelines based on large deformation theory as claimed in claim 1, It is characterized in that The existing pipeline mechanical response analysis method based on large deformation theory also includes: When the first judgment result is yes, the pipeline unit whose displacement vector of the existing pipeline is smaller than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as a separation node, and the pipeline unit is a unit obtained by dividing the existing pipeline into equal lengths; determining the length of the soil gap according to the number of separation nodes; Determine the height of the soil gap corresponding to each separation node according to the difference between the displacement vector corresponding to each separation node and the settlement of the underlying soil; The length of the soil gap and the height of the soil gap are output.

5. According to the method for analyzing mechanical response of existing pipelines based on large deformation theory as claimed in claim 1, It is characterized in that The soil-structure contact model is: ([M]-[N]+[K]){w}={q 1 }+{K}{S 2 } Wherein, [M] is the stiffness matrix of the moment at the end of the existing pipeline, [N] is the stiffness matrix of the axial force of the existing pipeline, [K] is the stiffness matrix of the roadbed reaction coefficient, {w} is the displacement vector of the existing pipeline, {q 1 } is the stress vector caused by the settlement of the overlying soil above the existing pipeline, {S 2 } is the displacement vector of the soil under the existing pipeline.

6. The existing pipeline mechanical response analysis method based on large deformation theory according to claim 1, It is characterized in that The following formula is used to update the pipeline's own related parameters: Wherein, g is the ratio of the deformed length of the existing pipeline to the initial length, h is the proportional parameter, w is the displacement vector of the existing pipeline, w' is the derivative of the displacement vector of the existing pipeline, x is the horizontal component of the ground deformation caused by the tunnel, [M] is the stiffness matrix of the moment at the end of the existing pipeline, E is the elastic modulus of the existing pipeline, I is the section moment of inertia, l is the length of the existing pipeline, and g n is the ratio of the deformed length of the existing pipeline to the initial length in the nth pipeline unit, n is the nth pipeline unit, and [N] is the stiffness matrix of the axial force of the existing pipeline.

7. The existing pipeline mechanical response analysis method based on large deformation theory according to claim 1, It is characterized in that The soil-structure separation model is: ([M]-[N]+[K][H]){w}={q 1 }+{K}[H]{S 2 } Wherein, [M] is the stiffness matrix of the moment at the end of the existing pipeline, [N] is the stiffness matrix of the axial force of the existing pipeline, [K] is the stiffness matrix of the roadbed reaction coefficient, {w} is the displacement vector of the existing pipeline, {q 1 } is the stress vector caused by the settlement of the overlying soil above the existing pipeline, {S 2 } is the displacement vector of the soil under the existing pipeline, and [H] is the criterion matrix.

8. The existing pipeline mechanical response analysis method based on large deformation theory according to claim 1, It is characterized in that The calculation formula for the underlying soil settlement is: Among them, S 2 (x) is the settlement of the underlying soil, is the maximum settlement of the underlying soil, x is the horizontal component of the ground deformation caused by the tunnel, and i is the horizontal distance from the center line of the tunnel to the inflection point of the settlement trough.

9. A mechanical response analysis system for existing pipelines based on large deformation theory, It is characterized in that include: An engineering parameter acquisition unit, used to acquire engineering parameters, the engineering parameters including: geometric parameters of the target pipeline and geotechnical parameters of the area where the target pipeline is located; A first calculation unit is used to calculate pipeline deformation related parameters according to the engineering parameters, wherein the pipeline deformation related parameters include pipeline self related parameters and pipeline environment related parameters, wherein the pipeline self related parameters include the stiffness matrix of the existing pipeline end moment and the stiffness matrix of the existing pipeline axial force, and the pipeline environment related parameters include the stiffness matrix of the roadbed reaction coefficient, the stress vector caused by the settlement of the overlying soil above the existing pipeline, and the displacement vector of the soil below the existing pipeline; A second calculation unit is used to substitute the pipeline deformation related parameters into a soil-structure contact model to calculate an initial displacement vector of the existing pipeline, wherein the soil-structure contact model is a function of the pipeline deformation related parameters and the displacement vector of the existing pipeline; A third calculation unit is used to calculate the settlement of the underlying soil in the area where the existing pipeline is located according to the engineering parameters; A first judgment unit is used to judge whether the initial displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a first judgment result; A first parameter updating unit, configured to update the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain updated first pipeline-related parameters when the first judgment result is no; A fourth calculation unit is used to substitute the updated first pipeline self-related parameters and the pipeline environment-related parameters into the soil-structure contact model to calculate the displacement vector of the first existing pipeline; A second judgment unit is used to judge whether the difference between the displacement vector of the first existing pipeline and the initial displacement vector of the existing pipeline is less than a first preset threshold value, and obtain a second judgment result; A first returning unit, configured to use the displacement vector of the first existing pipeline as the initial displacement vector of the existing pipeline and return the first parameter updating unit when the second judgment result is no; A first output unit, configured to output a displacement vector of the first existing pipeline when the second judgment result is yes; A criterion matrix setting unit, used for setting a criterion matrix when the first judgment result is yes, wherein the criterion items in the criterion matrix correspond to the magnitude relationship between the displacement vector of the existing pipeline and the settlement of the underlying soil in the area where the existing pipeline is located, and the criterion item where the displacement vector of the existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located is recorded as 0; A second parameter updating unit, configured to update the pipeline-related parameters according to the initial displacement vector of the existing pipeline to obtain updated second pipeline-related parameters; a fifth calculation unit, for substituting the updated second pipeline self-related parameters, the pipeline environment-related parameters and the criterion matrix into a soil-structure separation model to calculate a displacement vector of a second existing pipeline, wherein the soil-structure separation model is a function of pipeline deformation-related parameters, the criterion matrix and the displacement vector of the existing pipeline; A third judgment unit is used to judge whether the displacement vector of the second existing pipeline is less than the settlement of the underlying soil in the area where the existing pipeline is located, and obtain a third judgment result; A second returning unit, configured to, when the third judgment result is no, record the criterion item as 1 and return to the first parameter updating unit; a fourth judgment unit, configured to judge whether a difference between the displacement vector of the second existing pipeline and the initial displacement vector of the existing pipeline is less than a second preset threshold value when the third judgment result is yes, to obtain a fourth judgment result; a third returning unit, configured to use the displacement vector of the second existing pipeline as the initial displacement vector of the existing pipeline and return the result to the second parameter updating unit when the fourth judgment result is no; The second output unit is configured to output the displacement vector of the second existing pipeline when the fourth judgment result is yes.

10. The existing pipeline mechanical response analysis system based on large deformation theory according to claim 9, It is characterized in that The existing pipeline mechanical response analysis system based on large deformation theory also includes: An internal force calculation and output unit is used to calculate the internal force according to the displacement vector of the first existing pipeline and output the internal force when the second judgment result is yes.

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