CN-122021106-A - Near-field dynamics-based cut-off wall defect evaluation method

CN122021106ACN 122021106 ACN122021106 ACN 122021106ACN-122021106-A

Abstract

The invention discloses a near-field dynamics-based cut-off wall defect evaluation method, and relates to the technical field of cut-off engineering safety evaluation. The method comprises the steps of firstly establishing a structural model of the seepage wall with the defects, defining a mechanical equation, defect boundary conditions and load constraint, dispersing the structure into substance points, constructing a key connection relation and deducing a micro modulus coefficient, deducing a near-field dynamic control equation, setting a key fracture criterion and a damage evolution model, introducing a proportional boundary shape function, converting the dynamic control equation into a matrix form balance equation and solving dynamic response, calculating a damage value, and evaluating the safety performance and the residual service life of the seepage wall by combining a safety index. The invention combines the advantages of near-field dynamics and proportional boundary finite element methods, combines evaluation precision and efficiency, and provides reliable technical support for the safety guarantee of the impervious wall.

Inventors

YE WENBIN
GAN LEI
LIU JUN
YU WEI
Xi Shidai
WANG HAIBO
LIU ZHI
ZHANG ZHEN
SONG XINWEI

Assignees

河海大学
大连理工大学
江西省水利科学院(江西省大坝安全管理中心、江西省水资源管理中心)
西藏农牧大学

Dates

Publication Date: 20260512
Application Date: 20251217

Claims (10)

1. A near field dynamics based method for evaluating defects of a diaphragm wall, comprising: obtaining geometric parameters, material properties, defect information, load and constraint conditions of the impervious wall, and establishing a structural model of the impervious wall with the defects; Dispersing the structural model into substance points, constructing a bond connection relationship among the substance points, and determining a micro modulus coefficient of a bond based on an energy equivalent principle; deducing a near-field dynamics dynamic control equation, setting a key fracture criterion and a damage evolution model, and recording the fracture state of a key; introducing a proportional boundary shape function, converting the dynamic control equation into a dynamic balance equation in a matrix form, and solving to obtain the dynamic response of the object particles; and calculating the damage value of the impervious wall according to the dynamic response, and comprehensively judging the safety performance and the residual service life of the impervious wall by combining the safety performance evaluation index.
2. The method for evaluating defects of a diaphragm wall based on near field dynamics as claimed in claim 1, wherein the structural model of the diaphragm wall containing defects is established, and the geometrical equation, the physical equation and the constitutive relation of the structural domain are determined by solid mechanics theory, wherein the formula is that , wherein, As a vector of the strain, As a result of the displacement vector being a function of the displacement vector, Is a differential operator matrix, a physical equation Wherein As a vector of the stress and, Is an elastic matrix.
3. The near field dynamics-based diaphragm wall defect evaluation method according to claim 1, wherein when the structural model is discretized into object points, the object point distance h is not less than 5 units in the thickness direction of the wall and not less than 10 units in the length direction, and the micro modulus tensor expression of the key is Wherein Is the relative position vector between the object points, For the length of the vector modulus, The micro modulus coefficient is derived by the energy equivalent principle Wherein In order to achieve a bulk modulus of the material, To influence the domain radius for a point of matter, Is the modulus of elasticity of the material, Is poisson's ratio.
4. The near field dynamics-based diaphragm wall defect evaluation method according to claim 3, wherein when the near field dynamics dynamic control equation is obtained, the momentum conservation equation is Wherein Is the moment of time Particle(s) Is used for the acceleration of the vehicle, Is composed of radius Inner particles The field of view of the collection, Is a particle The volume to be occupied is such that, Is a pair of force vectors that are aligned, Is a vector of the relative positions of the two, Is a particle The pair force vector satisfies the law of action and reaction, and the expression is And (2) and 、 , In order to achieve the bonding deformation amount, As a tensor of the micro-modulus of the bond, Is the modulus of micro.
5. The near field dynamics-based diaphragm wall defect evaluation method according to claim 4, wherein the micro modulus coefficient Is decomposed into Wherein To be about Is expressed as an exponential function of , Is the characteristic length associated with the fracture process zone; By deducing the energy equivalence of localized deformation theory and continuous medium mechanics, the expression of the isotropic material is adapted to three-dimensional scene according to different dimensions Two-dimensional plane stress scenario Two-dimensional plane strain scene One-dimensional scene 。
6. The near field dynamics-based diaphragm wall defect evaluation method according to claim 4, wherein when the key breaking criterion is set, the elongation s of the key is used as a judgment basis, and the elongation expression is When (1) Reaching a critical value Determining bond breakage, no acting force exists between two particles after breakage, and the scalar function is dependent on history Recording the fracture state of the bond, and expressing the function as Particle(s) At the moment of time The effective damage value of (2) is calculated by influencing the proportion of broken bonds in the domain, and the expression is , Is a particle Occupied volume.
7. The near-field dynamics-based diaphragm wall defect evaluation method according to claim 1, wherein when converting the dynamic control equation into a dynamic equilibrium equation in a matrix form, introducing a near-field unit PE and a finite element unit FE, and discretizing a virtual work form of a partial differential equation momentum equation into Wherein Is PE (polyethylene), Is the number of PEs to be used, Is FE (alpha), Is the number of FEs that are to be processed, According to interpolation theory, the displacement on PE and FE is represented by a shape function N, and the node displacement d meets the following condition , And (2) and 、 Virtual work equation writing Further obtaining a linear equation set of total node displacement , As a matrix of the global stiffness, Is the total load vector.
8. The near-field dynamics-based diaphragm wall defect evaluation method according to claim 1, wherein when the proportional boundary shape function is introduced, geometric mapping and coordinate system conversion of polygonal units in the proportional boundary finite element are performed first, coordinates of line units are obtained through interpolation, and the interpolation function is that At any point on the line element The coordinates satisfy 、 , 、 Is the coordinates of the points in the line units, 、 Is the coordinate difference of the end points of the line units, and the coordinate of any point in the triangular fan passes through the intersection point of the point and the line segment of the scaling center of the line units Determining and coordinates satisfying 、 Realizing the change from a Cartesian coordinate system to a proportional boundary coordinate system Is a transition of (2).
9. The near field dynamics-based diaphragm wall defect evaluation method according to claim 8, wherein the geometric relationship between the cartesian coordinate system and the proportional boundary coordinate system is that Wherein In the form of a jacobian matrix, Is a jacobian matrix associated with only line cells, its determinant , 、、、 The differential operator is converted into a proportional boundary coordinate system through mapping, and the two end point coordinates of the line unit respectively meet the requirements of Wherein , 。
10. The near field dynamics-based diaphragm wall defect evaluation method according to claim 1, wherein the proportional boundary shape function is derived by solving a Laplace equation and applying a Galerkin method, wherein the Laplace equation is Potential function Weighting function Substituting the potential function and the weight function into the equation and expanding the integral to obtain the Euler-Cauchy differential equation Introducing Hamiltonian matrix Solving the eigenvalue by adopting a standard program of a proportional boundary finite element method to obtain , As a matrix of feature vectors, As a value of the characteristic(s), , Boundary potential function value, proportional boundary shape function is Wherein the superscript (e) represents a triangle sector, the shape function is used for calculating the displacement of any point in the polygon unit, and the displacement expression is , 、 As the displacement vector of the node, Interpolation matrix for displacement, and 。

Description

Near-field dynamics-based cut-off wall defect evaluation method Technical Field The invention relates to the technical field of security assessment of seepage-proofing engineering, in particular to an assessment method of seepage-proofing wall defects based on near-field dynamics. Background In the fields of water conservancy, municipal administration, traffic and other seepage prevention engineering, the seepage prevention wall is used as a core seepage prevention barrier and is subjected to complex loads such as gravity, soil pressure, water pressure, corrosion, temperature change and the like and environmental effects for a long time, so that the defects such as cracks, holes, leakage channels and the like are easy to generate. The defects can damage the integrity and the seepage prevention function of the seepage prevention wall, so that the problems of underground water seepage, foundation pit water burst, surrounding stratum deformation and the like are caused, and serious safety accidents such as engineering instability, environmental damage and the like can be caused. Therefore, the safety performance and the seepage-proofing function of the seepage-proofing wall with the defects are accurately evaluated, so that the method is a key for guaranteeing the long-term stable operation of the engineering, and has important engineering practical value. At present, methods for evaluating defects and safety performance of the diaphragm wall mainly comprise a traditional mechanical analysis method, a finite element method and the like. The traditional mechanical analysis method is based on classical continuous medium mechanics, and solves stress and strain response by establishing a mechanical model of the diaphragm wall, but mathematical singular points can appear when the problem of discontinuity and stress concentration at the defect is solved, so that the mechanical behavior and damage evolution process of the defect area are difficult to accurately describe, and the evaluation result error is larger. The finite element method converts the continuum problem into a unit equation set for solving through grid discretization, and is widely applied to the analysis of the impervious wall, but the method has strict requirements on the quality of the grid. When dynamic damage processes such as crack extension, leakage channel development and the like are simulated, grid reconstruction is required to be frequently carried out, so that the calculation cost is increased, numerical errors are introduced, and the evaluation accuracy is affected. In addition, the finite element method has limitations in treating the problems of uneven dispersion, complex boundary conditions and surface effects of the impervious wall, and is difficult to meet the engineering requirements of high-precision evaluation. The near field dynamics PD is used as a non-local theory, adopts an integral equation to describe the interaction among the object particles, does not need to rely on a space partial differential equation, can naturally process the discontinuity and damage evolution in the structure, and has unique advantages in defect structure analysis. However, when near field dynamics is applied alone, there are problems such as low computational efficiency, sensitivity to non-uniform dispersion, and the like. The proportional boundary finite element method (SBFEM) is constructed through special coordinate transformation and shape functions, and has the characteristics of high grid flexibility and good calculation accuracy. The method has the advantages that the two are organically coupled, the advantages of the method can be fully developed, and the defect of the existing method in the fault assessment of the impervious wall is overcome. Therefore, it is needed to provide a method for evaluating the defects of the diaphragm wall by combining near-field dynamics and a proportional boundary finite element method, which overcomes the defects of the prior art. Disclosure of Invention Based on the technical problems, the application discloses a near-field dynamics-based cut-off wall defect evaluation method, which comprises the following steps: obtaining geometric parameters, material properties, defect information, load and constraint conditions of the impervious wall, and establishing a structural model of the impervious wall with the defects; Dispersing the structural model into substance points, constructing a bond connection relationship among the substance points, and determining a micro modulus coefficient of a bond based on an energy equivalent principle; deducing a near-field dynamics dynamic control equation, setting a key fracture criterion and a damage evolution model, and recording the fracture state of a key; introducing a proportional boundary shape function, converting the dynamic control equation into a dynamic balance equation in a matrix form, and solving to obtain the dynamic response of the object particles; and calcula