Method for analyzing influence of foundation pit construction on stability of adjacent subway structure

Abstract

The invention discloses a method for analyzing influence of foundation pit construction on stability of adjacent subway structures, and belongs to the technical field of underground engineering detection. The method comprises the following steps: collecting tunnel structure information and geological information; establishing a three-dimensional model based on the collected tunnel structure information and geological information; and obtaining the results of load change and soil deformation in the foundation pit construction process through a finite element method, and evaluating the influence on the subway structure. Scientific and reliable data support is provided for construction process optimization and construction mode selection.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering detection, and more particularly to a method for analyzing the impact of foundation pit construction on the stability of adjacent subway structures. Background Art

[0002] With the acceleration of urbanization, the development and utilization of underground space is increasing, especially in large cities, where foundation pit projects are frequently carried out. These foundation pit projects are often close to existing subway lines, and their construction activities may have an adverse effect on the structural stability of subway tunnels. It can be seen that it is of great practical significance to study how to ensure the safety and stability of adjacent subway tunnels during foundation pit construction.

[0003] However, in the prior art, there are few studies on how to ensure the safety and stability of adjacent subway tunnels during foundation pit construction, and the research on the influence of different construction technologies and procedures on the deformation of tunnel structures is not in-depth and systematic enough.

[0004] Therefore, how to provide a method for analyzing the impact of foundation pit construction on the stability of adjacent subway structures is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0005] In view of this, the present invention provides a method for analyzing the impact of foundation pit construction on the stability of adjacent subway structures, which is used to solve the technical problems existing in the above-mentioned prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for analyzing the impact of foundation pit construction on the stability of adjacent subway structures, comprising:

[0008] Collect tunnel structure and geological information;

[0009] Build a 3D model based on the collected tunnel structure and geological information;

[0010] The finite element method is used to obtain the results of load changes and soil deformation during foundation pit construction, and the impact on the subway structure is evaluated.

[0011] Furthermore, the tunnel structure information includes: material type, cross-sectional shape, and lining thickness of the tunnel.

[0012] Furthermore, the geological information includes: obtaining geological conditions around the foundation pit, and the geological conditions include: soil type, groundwater level, and soil layer distribution.

[0013] Furthermore, the three-dimensional model is established based on the collected tunnel structure information and geological information, including:

[0014] Based on the collected tunnel structure information, determine the areas that need to be modeled, including the foundation pit itself, the adjacent subway tunnel, and the surrounding strata within a preset range;

[0015] Use geological modeling software to indicate the shape, size and excavation depth of the foundation pit;

[0016] Use geological modeling software to draw the cross-sectional shape and lining thickness of the tunnel;

[0017] Use geological modeling software to draw steel supports and concrete walls;

[0018] The initial three-dimensional model is obtained through the above steps;

[0019] Based on the collected geological information, the distribution of soil layers at different depths is automatically defined and annotated in the initial 3D model to obtain the final 3D model.

[0020] Furthermore, the geological modeling software is either AutoCAD software or Bentley MicroStation software.

[0021] Furthermore, based on the collected geological information, the soil layer distribution at different depths is automatically defined and annotated in the initial three-dimensional model to obtain the final three-dimensional model, including:

[0022] The geological data is processed by using the soil layer automatic division method based on Bayesian theory to automatically divide the soil layer information at different depths;

[0023] The soil layer information is marked in the initial 3D model, including the name, thickness and properties of the soil layer;

[0024] The final three-dimensional model is obtained.

[0025] Furthermore, the finite element method is used to obtain the results of load changes and soil deformation during the foundation pit construction process, and the impact on the subway structure is evaluated, including:

[0026] Use finite element pre-processing software to import the three-dimensional model and perform meshing;

[0027] Construct the control equation and use the finite element method to solve the control equation to obtain the results of load change and soil deformation during foundation pit construction;

[0028] Based on the results, the impact on the subway structure is evaluated.

[0029] Furthermore, the use of finite element pre-processing software to import the three-dimensional model and perform meshing includes:

[0030] Encapsulate the final three-dimensional model in a three-dimensional rectangular grid;

[0031] The three-dimensional rectangular grid is meshed, wherein the main area of ​​the foundation pit wall and the subway tunnel is meshed using hexahedral units, and the area outside the main area is meshed using tetrahedral units.

[0032] Furthermore, the finite element pre-processing software includes: any one of Hypermesh software, ANSYS Workbench software or Abaqus CAE software.

[0033] Furthermore, the constructed control equation includes:

[0034] Balanced equation:

[0035] σ ij +f j =0

[0036] In the formula, σ ij is the stress tensor, f j It is the volume force;

[0037] Constitutive relations:

[0038]

[0039] In the formula, ε ij is the strain tensor, E is the elastic modulus, δ ij is the Kronecker symbol, v is the Poisson's ratio, σ kk trace of the stress tensor;

[0040] Geometric equations:

[0041]

[0042] In the formula, u i is the displacement component, u j,i is the displacement gradient;

[0043] Seepage equation:

[0044]

[0045] In the formula, is the gradient operator, k is the permeability coefficient, h is the hydraulic head height, and q is the source and sink term.

[0046] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method for analyzing the stability of adjacent subway structures affected by foundation pit construction, constructs a detailed finite element model to simulate the load changes and soil deformation during foundation pit construction, and evaluates its impact on adjacent subway structures. This method not only helps to understand the potential impact of construction activities on underground structures, but also provides a scientific basis for optimizing construction plans. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0048] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0049] 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.

[0050] See also Figure 1 The embodiment of the present invention discloses a method for analyzing the impact of foundation pit construction on the stability of adjacent subway structures, comprising:

[0051] Collect tunnel structure and geological information;

[0052] Build a 3D model based on the collected tunnel structure and geological information;

[0053] The finite element method is used to obtain the results of load changes and soil deformation during foundation pit construction, and the impact on the subway structure is evaluated.

[0054] Specifically, the present invention collects tunnel structure information and geological information, and uses finite element analysis to establish a three-dimensional model based on the collected tunnel structure information and geological information, simulates the load changes and soil deformation during foundation pit construction, and evaluates the impact on the subway structure.

[0055] Specifically, the tunnel structure information includes: tunnel material type, cross-sectional shape, and lining thickness.

[0056] Specifically, the geological information includes: obtaining geological conditions around the foundation pit, and the geological conditions include: soil type, groundwater level, and soil layer distribution.

[0057] In a specific embodiment, building a three-dimensional model based on the collected tunnel structure information and geological information includes:

[0058] Based on the collected tunnel structure information, determine the areas that need to be modeled, including the foundation pit itself, the adjacent subway tunnel, and the surrounding strata within a preset range;

[0059] Use geological modeling software to indicate the shape, size and excavation depth of the foundation pit;

[0060] Use geological modeling software to draw the cross-sectional shape and lining thickness of the tunnel;

[0061] Use geological modeling software to draw steel supports and concrete walls;

[0062] The above is the establishment of structural features. At the same time, for non-critical parts, the model can be appropriately simplified to reduce the amount of calculation, but it must not affect the accuracy of the overall analysis results. Ensure that all key structural features that may affect stress distribution and deformation are retained, and obtain the initial three-dimensional model through the above steps;

[0063] The next step is geological stratification: based on the collected geological information, the distribution of soil layers at different depths is automatically defined and annotated in the initial 3D model to obtain the final 3D model.

[0064] Specifically, it includes but is not limited to saving the final three-dimensional model in a format suitable for finite element analysis software, such as .STP, .IGES or .NASTRAN.

[0065] Specifically, the geological modeling software is any one of AutoCAD software or Bentley MicroStation software.

[0066] In a specific embodiment, based on the collected geological information, soil layer distribution at different depths is automatically defined and annotated in the initial three-dimensional model to obtain a final three-dimensional model, including:

[0067] The geological data is processed by using the soil layer automatic division method based on Bayesian theory to automatically divide the soil layer information at different depths;

[0068] The soil layer information is marked in the initial 3D model, including the name, thickness and properties of the soil layer;

[0069] The final three-dimensional model is obtained.

[0070] Specifically, Bayesian theory is a probability-based statistical method that uses prior information and sample data to calculate posterior probability. In soil layer division, the Bayesian method can automatically divide soil layers and evaluate the uncertainty of soil layer interfaces based on the characteristics of geological data. Specifically, it includes the following steps:

[0071] Based on the collected geological data, it is necessary to determine the number of soil layers N and the thickness of each soil layer Hn (n = 1, 2, ..., N);

[0072] The prior distribution of soil layer thickness P(HN|N) reflects the prior information about soil layer thickness before obtaining geological data (which is usually based on the engineering experience and prior judgment of engineers);

[0073] The likelihood function P(ξ|HN,N) quantitatively reflects the information about soil layer thickness provided by geological data. Here, ξ represents the set of geological data, such as the logarithm of CPT data.

[0074] According to Bayes' theorem, combining the prior distribution and the likelihood function, the posterior distribution of the soil thickness P(HN|ξ,N) can be calculated. This posterior distribution reflects the most likely value of the soil thickness and its uncertainty under given geological data.

[0075] Through the posterior distribution, the most likely soil layer interface depth DN = {Dn,n = 1,2,...,N-1} can be determined. These interface depths are the basis for soil layer division;

[0076] The standard deviation of the soil layer interface depth is calculated as a quantitative indicator of the uncertainty of the soil layer interface, which helps to evaluate the reliability of the soil layer division.

[0077] In a specific embodiment, the finite element method is used to obtain the results of load changes and soil deformation during foundation pit construction, and the impact on the subway structure is evaluated, including:

[0078] Use finite element pre-processing software to import the three-dimensional model and perform meshing;

[0079] Construct the control equation and use the finite element method to solve the control equation to obtain the results of load changes and soil deformation during foundation pit construction, such as stress distribution, displacement changes, etc.

[0080] Based on the results, the impact on the subway structure is evaluated to determine whether there are potential risks such as excessive settlement, tilting or crack extension.

[0081] Furthermore, the use of finite element pre-processing software to import the three-dimensional model and perform meshing includes:

[0082] Encapsulate the final three-dimensional model in a three-dimensional rectangular grid;

[0083] The three-dimensional rectangular grid is meshed, and the main area of ​​the foundation pit wall and subway tunnel is meshed using hexahedral units to improve the calculation accuracy;

[0084] Tetrahedral elements are used for meshing the area outside the main body to save computing resources.

[0085] Specifically, set finer grids in stress concentration areas and deformation sensitive areas, set reasonable grid density transition zones, ensure smooth transition between grids of different densities, and ensure that the generated grid has no distortion, inversion, etc., and adjust the grid parameters and re-divide if necessary.

[0086] Furthermore, the finite element pre-processing software includes: any one of Hypermesh software, ANSYS Workbench software or Abaqus CAE software.

[0087] Furthermore, the constructed control equation includes:

[0088] Balanced equation:

[0089] σ ij +f j =0

[0090] In the formula, σ ij is the stress tensor, f j It is the volume force;

[0091] Constitutive relations:

[0092]

[0093] In the formula, ε ij is the strain tensor, E is the elastic modulus, δ ij is the Kronecker symbol, v is the Poisson's ratio, σ kk trace of the stress tensor;

[0094] Geometric equations:

[0095]

[0096] In the formula, u i is the displacement component, u j,i is the displacement gradient;

[0097] Seepage equation:

[0098]

[0099] In the formula, is the gradient operator, k is the permeability coefficient, h is the hydraulic head height, and q is the source and sink term.

[0100] 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 device 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.

[0101] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for analyzing the impact of foundation pit construction on the stability of adjacent subway structures, characterized in that: include: Collect tunnel structure and geological information; Build a 3D model based on the collected tunnel structure and geological information; The finite element method is used to obtain the results of load changes and soil deformation during foundation pit construction, and the impact on the subway structure is evaluated.

2. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 1 is characterized in that: The tunnel structure information includes: tunnel material type, cross-sectional shape, and lining thickness.

3. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 1 is characterized in that: The geological information includes: obtaining geological conditions around the foundation pit, and the geological conditions include: soil type, groundwater level, and soil layer distribution.

4. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 1 is characterized in that: The three-dimensional model is established based on the collected tunnel structure information and geological information, including: Based on the collected tunnel structure information, determine the areas that need to be modeled, including the foundation pit itself, the adjacent subway tunnel, and the surrounding strata within a preset range; Use geological modeling software to indicate the shape, size and excavation depth of the foundation pit; Use geological modeling software to draw the cross-sectional shape and lining thickness of the tunnel; Use geological modeling software to draw steel supports and concrete walls; The initial three-dimensional model is obtained through the above steps; Based on the collected geological information, the distribution of soil layers at different depths is automatically defined and annotated in the initial 3D model to obtain the final 3D model.

5. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 4 is characterized in that: The geological modeling software is either AutoCAD software or Bentley MicroStation software.

6. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 4 is characterized in that: Based on the collected geological information, the soil layer distribution at different depths is automatically defined and annotated in the initial three-dimensional model to obtain the final three-dimensional model, including: The geological data is processed by using the soil layer automatic division method based on Bayesian theory to automatically divide the soil layer information at different depths; The soil layer information is marked in the initial 3D model, including the name, thickness and properties of the soil layer; The final three-dimensional model is obtained.

7. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 1 is characterized in that: The finite element method is used to obtain the load change and soil deformation results during the foundation pit construction process, and to evaluate the impact on the subway structure, including: Use finite element pre-processing software to import the three-dimensional model and perform meshing; Construct the control equation and use the finite element method to solve the control equation to obtain the results of load change and soil deformation during foundation pit construction; Based on the results, the impact on the subway structure is evaluated.

8. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 7 is characterized in that: The method of using finite element pre-processing software to import the three-dimensional model and perform meshing includes: Encapsulate the final three-dimensional model in a three-dimensional rectangular grid; The three-dimensional rectangular grid is meshed, wherein the main area of ​​the foundation pit wall and the subway tunnel is meshed using hexahedral units, and the area outside the main area is meshed using tetrahedral units.

9. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 7 is characterized in that: The finite element pre-processing software includes: any one of Hypermesh software, ANSYS Workbench software or Abaqus CAE software.

10. The method for analyzing the stability of adjacent subway structures affected by foundation pit construction according to claim 7, characterized in that: The constructed control equations include: Balanced equation: s ij +f j =0 In the formula, σ ij is the stress tensor, f j It is the volume force; Constitutive relations: In the formula, ε ij is the strain tensor, E is the elastic modulus, δ ij is the Kronecker symbol, v is the Poisson's ratio, σ kk trace of the stress tensor; Geometric equations: In the formula, u i is the displacement component, u j,i is the displacement gradient; Seepage equation: In the formula, is the gradient operator, k is the permeability coefficient, h is the hydraulic head height, and q is the source and sink term.

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